Water resource assessment for 
the Southern Gulf catchments 

 
Australia’s National 
Science Agency 
A report from the CSIRO Southern Gulf Water Resource 
Assessment for the National Water Grid 

Editors: Ian Watson, Caroline Bruce, Seonaid Philip, Cuan Petheram and Chris Chilcott 

 

 



ISBN 978-1-4863-2081-3 (print) 

ISBN 978-1-4863-2082-0 (online) 

Citation 

Watson I, Bruce C, Philip S, Petheram C and Chilcott C (eds) (2024) Water resource assessment for the Southern Gulf catchments. A report from the 
CSIRO Southern Gulf Water Resource Assessment for the National Water Grid. CSIRO, Australia. 

Chapters should be cited in the format of the following example: Philip S, Watson I, Petheram C and Bruce C (2024) Chapter 1: Preamble. In: Watson 
I, Bruce C, Philip S, Petheram C, and Chilcott C (eds) (2024) Water resource assessment for the Southern Gulf catchments. A report from the CSIRO 
Southern Gulf Water Resource Assessment for the National Water Grid. CSIRO, Australia. 

Copyright 

© Commonwealth Scientific and Industrial Research Organisation 2024. To the extent permitted by law, all rights are reserved and no part of this 
publication covered by copyright may be reproduced or copied in any form or by any means except with the written permission of CSIRO. 

Important disclaimer 

CSIRO advises that the information contained in this publication comprises general statements based on scientific research. The reader is advised 
and needs to be aware that such information may be incomplete or unable to be used in any specific situation. No reliance or actions must 
therefore be made on that information without seeking prior expert professional, scientific and technical advice. To the extent permitted by law, 
CSIRO (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, 
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CSIRO is committed to providing web accessible content wherever possible. If you are having difficulties with accessing this document, please 
contact Email CSIRO Enquiries
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CSIRO Southern Gulf Water Resource Assessment acknowledgements 

This report was funded through the National Water Grid’s Science Program, which sits within the Australian Government’s Department of Climate 
Change, Energy, the Environment and Water. 

Aspects of the Assessment have been undertaken in conjunction with the Northern Territory (NT) and Queensland governments. 

The Assessment was guided by two committees: 

i. The Governance Committee: CRC for Northern Australia/James Cook University; CSIRO; National Water Grid (Department of Climate 
Change, Energy, the Environment and Water); Northern Land Council; NT Department of Environment, Parks and Water Security; NT 
Department of Industry, Tourism and Trade; Office of Northern Australia; Queensland Department of Agriculture and Fisheries; 
Queensland Department of Regional Development, Manufacturing and Water 
ii. The Southern Gulf catchments Steering Committee: Amateur Fishermen’s Association of the NT; Austral Fisheries; Burketown Shire; 
Carpentaria Land Council Aboriginal Corporation; Health and Wellbeing Queensland; National Water Grid (Department of Climate 
Change, Energy, the Environment and Water); Northern Prawn Fisheries; Queensland Department of Agriculture and Fisheries; NT 
Department of Environment, Parks and Water Security; NT Department of Industry, Tourism and Trade; Office of Northern Australia; 
Queensland Department of Regional Development, Manufacturing and Water; Southern Gulf NRM 


Responsibility for the Assessment’s content lies with CSIRO. The Assessment’s committees did not have an opportunity to review the Assessment 
results or outputs prior to their release. 

This report was reviewed by Mr Mike Grundy (Independent consultant). Individual chapters were reviewed by Dr Peter Wilson, CSIRO (Chapter 2); 
Dr Andrew Hoskins, CSIRO (Chapter 3); Dr Brendan Malone, CSIRO (Chapter 4); Dr James Bennett, CSIRO (Chapter 5); Dr Nikki Dumbrell, CSIRO 
(Chapter 6); Mr Darran King, CSIRO (Chapter 7). The material in this report draws largely from the companion technical reports, which were 
themselves internally and externally reviewed. 

For further acknowledgements, see page xxviii. 

Acknowledgement of Country 

CSIRO acknowledges the Traditional Owners of the lands, seas and waters of the area that we live and work on across Australia. We acknowledge 
their continuing connection to their culture and pay our respects to their Elders past and present. 

Photo 

Saltwater Arm, a tributary of the Albert River. This view typifies the tidal rivers and estuaries along the southern coast of the Gulf of Carpentaria. 
Source: Shutterstock


Director’s foreword 

Sustainable development and regional economic prosperity are priorities for the Australian, 
Queensland and Northern Territory (NT) governments. However, more comprehensive 
information on land and water resources across northern Australia is required to complement 
local information held by Indigenous Peoples and other landholders. 

Knowledge of the scale, nature, location and distribution of likely environmental, social, cultural 
and economic opportunities and the risks of any proposed developments is critical to sustainable 
development. Especially where resource use is contested, this knowledge informs the consultation 
and planning that underpin the resource security required to unlock investment, while at the same 
time protecting the environment and cultural values. 

In 2021, the Australian Government commissioned CSIRO to complete the Southern Gulf Water 
Resource Assessment. In response, CSIRO accessed expertise and collaborations from across 
Australia to generate data and provide insight to support consideration of the use of land and 
water resources in the Southern Gulf catchments. The Assessment focuses mainly on the potential 
for agricultural development, and the opportunities and constraints that development could 
experience. It also considers climate change impacts and a range of future development pathways 
without being prescriptive of what they might be. The detailed information provided on land and 
water resources, their potential uses and the consequences of those uses are carefully designed to 
be relevant to a wide range of regional-scale planning considerations by Indigenous Peoples, 
landholders, citizens, investors, local government, and the Australian, Queensland and NT 
governments. By fostering shared understanding of the opportunities and the risks among this 
wide array of stakeholders and decision makers, better informed conversations about future 
options will be possible. 

Importantly, the Assessment does not recommend one development over another, nor assume 
any particular development pathway, nor even assume that water resource development will 
occur. It provides a range of possibilities and the information required to interpret them (including 
risks that may attend any opportunities), consistent with regional values and aspirations. 

All data and reports produced by the Assessment will be publicly available. 

 

Chris Chilcott 

C:\Users\bru119\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.Word\C_Chilcott_high.jpg
Project Director 

 














Key findings for the Southern Gulf catchments 
The Southern Gulf catchments have an area of 108,200 km2 across the Northern Territory (NT) and 
Queensland. They comprise the catchments of Settlement Creek (17,600 km2), Nicholson River 
(52,200 km2), Leichhardt River (33,400 km2) and, Morning Inlet (3,700 km2) and the Wellesley 
island groups (1,200 km2). The rivers of these catchments flow into the lower Gulf of Carpentaria, 
an important part of northern Australia’s marine environment with high ecological, cultural and 
economic values. Within the study area, 12% of the land is Aboriginal freehold tenure of which 
33% is national park, including the UNESCO World Heritage-listed Australian Fossil Mammal Sites 
(Riversleigh, Queensland). The dominant land use by area is extensive grazing of beef cattle on 
native rangelands, constituting 77% of the study area. Mining occupies less than 0.05% of the land 
area and irrigated agriculture, occupies about 0.01% (~1,400 ha). 
The population of the catchments in 2021 was approximately 22,500 people, of whom about 27% 
were Indigenous Australians. In comparison, Indigenous Australians make up 25% of the 
population of the NT, 4% of the population of Queensland and 3% of Australia as a whole. There is 
one significant urban area, Mount Isa (population 18,000) and Doomadgee (population 1,387) is 
the only other settlement with a population greater than 1,000. Distinct demographic and socio-
economic differences exist within the Southern Gulf catchments based on the differences between 
Mount Isa and the remainder of the study area. The population density outside Mount Isa is one 
of the lowest in Australia, and some communities in the study area are ranked as being among the 
most disadvantaged in Australia. 
Indigenous Peoples have continuously occupied and managed the Southern Gulf catchments for 
tens of thousands of years. They retain significant and growing rights and interests in land and 
water resources, including crucial roles in water and development planning and as co-investors in 
future development. Indigenous Peoples remain closely tied to their territory associations. The key 
language groups are Garawa, Gangalidda, Waanyi, Kukatj, Lardil, Yangkaal, Kaiadilt, Wakabunga, 
Nguburinji, Kalkadoon, Mitakoodi, Mayi-Kutuna, Mayi‑Thakurti, Mayi‑Yapi and Mayi-Yali. A 
number of related groups and subgroups occur within these regional ownership descriptors. 
The creeks and rivers of the Southern Gulf catchments contribute about 6% of the mean annual 
discharge into the Gulf of Carpentaria, supporting many important ecological assets, some of 
national significance, and existing industries such as the Northern Prawn Fishery. 
This fishery had a prawn catch across whole of northern Australia valued at $85 million in 
2019–20. While the Leichhardt River is deeply incised over much of its length, high-flow 
distributary channels have formed where the Nicholson and Gregory rivers flow across the 
extensive Armraynald Plain.
The Nicholson and Leichhardt rivers are the two largest rivers in the Southern Gulf catchments and 
have median annual discharges of 1,873 and 1,211 GL, respectively. The Settlement Creek 
catchment encompasses numerous relatively short rivers, including Running, Settlement, Lagoon, 
Eight Mile, Cliffdale and Moonlight creeks. The median annual discharge from the creeks within 
the Settlement Creek catchment is 1,304 GL. The Gregory River, which flows into the Nicholson 
ii | Water resource assessment for the Southern Gulf catchments 












River approximately 85 km from the coast, is the largest perennial river in semi‑arid Queensland. 
The Gregory River and its major tributary, Lawn Hill Creek, receive groundwater discharge 
throughout the dry season from the Cambrian Limestone Aquifer (CLA), which is comprised mostly 
of the Camooweal Dolostone and Thorntonia Limestone in the south of the study area. 
The concentration of mining and industrial activity around Mount Isa has resulted in sufficiently 
high water demand from high-value industries for the construction of five large, purpose-built 
reservoirs of at least 10 GL capacity in the Leichhardt catchment, including the Leichhardt Dam 
(Lake Moondarra) and Julius Dam (Lake Julius). Consequently, as a proportion of its median annual 
streamflow, the water in the Leichhardt River is more heavily regulated than most other rivers in 
northern Australia west of the Great Dividing Range. As a result of existing entitlements 
(105.7 GL/year) and licence conditions in the Leichhardt catchment, only limited quantities of 
water could be reliably available for irrigated agriculture from Julius Dam without affecting the 
reliability of water supply to existing water entitlement holders. The study area has numerous 
small dams (<10 GL) providing water to mines as well as farm-scale dams, several for irrigation, but 
the only other instream water structure of note is a low weir (<1 GL capacity) on the Nicholson 
River downstream of Doomadgee, which is used to supply water for the town. 
With irrigation, the Southern Gulf catchments have a climate that is suitable for a wide range of 
annual and perennial horticulture, and broadacre crops and forages. However, the opportunities 
and risks of irrigation development adjacent to each of the major rivers are starkly different. 
Adjacent to the east bank of the Gregory River downstream and slightly upstream of the township 
of Gregory, the grey cracking clay soils of the treeless Armraynald Plain are highly favourable for 
large-scale irrigation developments (based on instream dams) or small-scale irrigation 
developments (based on water harvesting). The large contiguous areas of soil suitable for 
broadacre irrigation and ringtanks (1.03 million ha) gently slope away from the Gregory River, 
enabling water to be efficiently distributed using gravity and natural distributary channels running 
away from the river. The most cost-effective potential site for a dam in the study area is located 
approximately 70 km upstream of the township of Gregory, but that potential dam’s reservoir 
would be located within a part of the Gregory River that is a nationally significant wetland, the 
Thorntonia Aggregation. Being one of the few perennial rivers in the Southern Gulf and 
neighbouring Flinders catchment region, the Gregory River is particularly highly valued by local 
residents. 
On the Nicholson River downstream of Doomadgee are contiguous areas of red sandy and loamy 
soils (totalling 23,000 ha) suitable for irrigated vegetables. However, in the absence of a dam 
upstream, on-farm storage of water for irrigated annual horticulture would be challenging due to 
the difficulty of constructing ringtanks on these sandy soils. These soils are unlikely to be suitable 
for perennial horticulture due to the risk of flooding. 
The Leichhardt catchment has opportunities for irrigated horticulture on the friable soils 
(103,000 ha) on the narrow levees of the Leichhardt River downstream of Kajabbi. Adjacent to 
these soils, and up to 1 km from the river, are friable clay soils suitable for broadacre irrigation. 
While these heavier soils are suitable for constructing ringtanks, conveying water pumped from 
the Leichhardt River across the sandy levee soils to ringtanks may be costly and inefficient in some 
locations. The proximity of the eastern side of the mid-reaches of the Leichhardt River to the Burke 
Developmental Road and Mount Isa would be an advantage to new irrigation developments 


compared with more remote parts of northern Australia. For example, the more remote Nicholson 
and Settlement Creek catchments are often inaccessible for long periods due to flooding during 
the wet season. 

It is physically possible that water harvesting could extract 150 GL of water in 75% of years, spread 
across the Nicholson and Leichhardt catchments, without affecting the reliability of supply of 
existing water entitlement holders. This extraction would reduce the median and mean annual 
discharge to the Gulf of Carpentaria from these catchments by 5% and 3%, respectively. It would 
be sufficient water to irrigate about 12,000 ha of mixed broadacre crops. 

A hypothetical total of 10,000 ha of irrigated mixed broadacre (85%) and horticulture (15%) 
agriculture in the Southern Gulf catchments, would result in total annual increased economic 
activity (direct and indirect) of potentially as much as $190 million and support up to 360 full-time-
equivalent jobs. 

In reality, the nature and scale of future surface water development would depend heavily upon 
community and government values, acceptance of potential impacts to water-dependent 
ecosystems, and the likely beneficiaries. Economic data from the NT and north-western 
Queensland indicate that, like other industries such as mining, grazing and fishing, benefits arising 
from agriculture developments elsewhere in the NT and Queensland have been heavily skewed to 
non-Indigenous households relative to Indigenous households. 

The most promising groundwater resources in the Southern Gulf catchments are the regional-
scale CLA and Gilbert River Aquifer (GRA). The CLA coincides with large, contiguous areas of 
cracking clay soils suitable for irrigated broadacre cropping (308,000 ha) along the south-western 
margin of the study area. However, groundwater discharge from the CLA provides the dry-season 
flow in Lawn Hill Creek and the Gregory and O’Shannassy rivers and some of their tributaries. The 
major rivers of the Southern Gulf catchments are also characterised by relatively extensive alluvial 
aquifers, up to 5 km either side of the river. These systems are poorly characterised but likely to be 
highly heterogeneous and connected to the rivers, meaning the alluvial aquifers could be 
recharged by and discharge into ‘connected’ rivers at different times of the year. In addition to the 
3.5 GL of existing groundwater entitlements in the study area, it is physically possible that 
groundwater systems across the Southern Gulf catchments could supply up to approximately 30 
GL of water per year for irrigated agriculture, sufficient to irrigate about 4,000 ha of mixed 
broadacre cropping. Up to 10 GL of additional groundwater per year could potentially be extracted 
for other uses from areas of hard rock (i.e. poor soil) and poor water quality. The actual quantity of 
water extracted, however, would depend on community and government acceptance of impacts 
to groundwater-dependent ecosystems (GDEs) and existing groundwater users. 

Irrigated agriculture and aquaculture in the Southern Gulf catchments is only likely to be 
financially viable where there is an alignment of good prices for high‑value crops and market 
advantages. This makes achieving scale challenging. Other factors include availability of suitable 
markets for the products, investment in fundamental infrastructure such as all-weather roads and 
bridges and land tenure arrangements. New agricultural developments in the study area, if they 
were to eventuate, are likely to start irrigating broadacre crops on heavier clay soils before 
progressing to higher‑value and higher-input enterprises, such as horticulture on sandy and loamy 
soils, as farmers build confidence in their skills and expertise in this largely greenfield region. 
Landholders could potentially transition from broadacre cropping to annual horticulture on the 


heavy clay soils and nearby sandy levees adjacent to the Leichhardt River. Along the lower coastal 
reaches, about 194,000 ha of land is suitable for prawn and barramundi aquaculture, using 
earthen ponds. For all of the area estimates noted above, the land is considered suitable but with 
minor to considerable limitations and would require careful soil management. 

Growing irrigated forages or hay to feed young cattle to improve market access or to enable sale 
at younger ages is unlikely to be financially viable. Irrigation increases beef production but 
requires high capital outlay, and gross margins would be reasonably similar to, or less than, 
baseline cattle operations. Consistent rainfed cropping in the catchment is likely to be 
opportunistic (only possible in suitable years) and depend upon farmers’ appetite for risk and 
future local demand. How land cultivated for rainfed agriculture is managed in the years when 
rainfall is insufficient for rainfed cropping will be crucial for sustainable farming operations and the 
industry’s social licence to operate. 

Changes to groundwater baseflow and streamflow under projected drier future climates are likely 
to be considerably greater than changes that would result from plausible groundwater and surface 
water developments. Of the global climate models examined, 44% projected a drier future climate 
over the Southern Gulf catchments and 40% projected ‘little change’. Adopting a conservatively 
dry global climate model projection of a 13% reduction in long‑term mean annual rainfall and a 9% 
increase in potential evaporation, the modelled reduction in median annual discharge to the Gulf 
of Carpentaria from the Nicholson and Leichhardt catchments was 30%. 

The Southern Gulf catchments, although not pristine, have many unique characteristics and 
valuable ecological assets, which support existing industries such as grazing, tourism and 
commercial fishing. Whether based on groundwater or offstream storage, irrigated agricultural 
development has a wide range of potential benefits and risks that differentially intersect diverse 
stakeholder views on ecology, economy and culture. The detailed reports upon which this 
summary is based provide information that can be used to help consider the trade-offs from 
potential developments. 



Leichhardt River flowing through the Isa Highlands 

Photo: CSIRO – Nathan Dyer 



Overview of the Southern Gulf catchments 

The Southern Gulf catchments comprise four river basins defined by the Australian Water 
Resource Council, referred to here as catchments, that discharge into the Gulf of Carpentaria: 
Settlement Creek, Nicholson, Leichhardt and Morning Inlet. The study area also encompasses the 
Wellesley islands groups. 

The Southern Gulf catchments have a highly variable climate 

Northern Australia’s tropical climate is notable for the extremely high variability of rainfall 
between seasons and especially between years. This has major implications for evaluating and 
managing risks to development, infrastructure and industry. 

The climate of the Southern Gulf catchments is hot and semi-arid to dry subhumid. Generally, 
these catchments are water-limited environments, so efficient and effective methods for 
capturing, storing and using water are critical. 


•The mean and median annual rainfall – averaged across the Southern Gulf catchments – are 
602 mm and 554 mm, respectively. A strong rainfall gradient runs from Mornington Island in the 
north (1,150 mm annual median) to the south of Mount Isa (400 mm annual median).
•Averaged across the catchments, 6% of the rainfall occurs in the dry season (May to October). 
Median annual dry‑season rainfall ranges from 15 mm in the south-east to 60 mm along the 
western boundary.
•Annual rainfall totals in the Southern Gulf catchments are highly variable. Annual totals are 
approximately 1.3 times more variable than in comparable parts of the world.


The seasonality of rainfall presents opportunities and challenges for both wet- and dry-season 
cropping. 

•Information about water availability (i.e. soil water and water in storages) helps minimise risk 
when it is known ahead of important agricultural decisions – before planting time for most 
dry-season planted crops. Such information allows farmers to manage risk by choosing crops 
that optimise use of the available water or by deciding to forego cropping for a season.


Rainfall is difficult to store. 

•Mean annual potential evaporation is higher than rainfall, averaging about 1,850 mm over mostof the study area, with the highest values near the mouth of the Leichhardt River and MorningInlet.
•Large farm-scale ringtanks lose about 30% to 50% of their water to evaporation and seepagebetween April and October. Deeper farm-scale gully dams lose about 20% to 40% of their waterover the same period. Using stored water early in the season is the most effective way to reducethese losses.


The more promising agricultural land in the Southern Gulf catchments is in the middle to lower 
reaches of the rivers, which are the parts of the study area most susceptible to destructive 
cyclonic winds. 


•Of the 53 consecutive cyclone seasons prior to 2021–22, the Southern Gulf catchments had notropical cyclones in 60% of those seasons, one cyclone in 36% of seasons and two cyclones in 4%
of seasons.


More than twice as many global climate models project a drier future climate than a wetter 
future climate for the Southern Gulf catchments, thus it is prudent to plan for water scarcity. 

•For the Southern Gulf catchments, 44% of climate models project a drier future, 16% project awetter future and 40% project a future within ±5% of the historical mean, indicating ‘littlechange’. Other studies indicate that tropical cyclones will be fewer but more intense in thefuture, although uncertainties remain.
•Palaeoclimate records indicate past climates have been both wetter and drier over the pastseveral thousand years.
•Climate and hydrology data that support short- to medium-term water resource planning shouldcapture the full range of likely or plausible conditions and variability at different timescales, andparticularly for periods when water is scarce. These are the periods that most affect industryand the environment. When industries ‘compete’ with the environment for water when it ismost scarce, it can have profound long-term consequences to both if the scarcity is poorlyunderstood and not planned for.
•Future changes in temperature, vapour pressure deficit, solar radiation, wind speed and carbondioxide concentrations will separately act to increase or decrease crop water demand and cropyield under irrigation in northern Australia. For example, during the cooler months of the dryseason, cotton in the more southerly parts of the Southern Gulf catchments (e.g. BarklyTableland) may be limited by minimum temperatures at key stages of cotton boll development.
Higher temperatures may increase the irrigation water requirement, depending upon whetherother climate variables such as wind speed increase or decrease in the future. However, forsome crops, higher crop water demand, and hence smaller planted area, could be offset byhigher yields and lower risk of crop failure.
•Changes under future climates to the amount of irrigation water required and crop yield arelikely to be modest compared to improvements arising from new crop varieties and technologyover the next 40 years. Historically, these types of improvements have been difficult to predict,
but they are potentially large.


The Southern Gulf catchments are comprised of many different types of rivers and creeks 

The rivers and creeks of the Southern Gulf catchments constitute about 6% of the mean annual 
flow into the Gulf of Carpentaria, an important part of northern Australia’s marine environment 
with high ecological and economic values. 

•The mean and median annual discharges from the Southern Gulf catchments into the Gulf ofCarpentaria are 6,759 and 4,961 GL, respectively.
•The Nicholson and Leichhardt rivers are the two largest rivers in the Southern Gulf catchments.
The Nicholson River has the 13th largest median annual discharge (1,873 GL) of all rivers thatflow into the Gulf of Carpentaria, and the Leichhardt River has the 16th largest (1,211 GL).



•The Settlement Creek catchment encompasses numerous relatively short creeks and its medianannual discharge to the Gulf of Carpentaria is 1,304 GL. The median annual discharges from theMorning Inlet catchments and the Wellesley Island groups are 195 and 173 GL, respectively.
•Annual variability in streamflow in the Southern Gulf catchments is comparable with other riversin northern Australia with similar mean annual runoff, but the annual variability in runoff is twoto three times greater than rivers in the rest of the world in similar climates.


Broad-scale flooding occurs along the lower reaches of the rivers of the Southern Gulf 
catchments, particularly adjacent to the distributary channels from the Nicholson and Gregory 
rivers to the Albert River. 

•Between 1980 and 2023 (43 years), 51 streamflow events broke the banks of the Gregory Riverat Riversleigh Road crossing. All events occurred between November and April (inclusive), andabout 84% of events occurred between January and March (inclusive).


Under a potential dry future climate (13% reduction in rainfall), median annual discharges from 
the Nicholson and Leichhardt rivers are projected to decrease by approximately 30%. 

The Leichhardt catchment is one of the most regulated catchments in northern Australia, west 
of the Great Dividing Range, based on extractions as a proportion of its median annual flow. 

•Current licensed surface water extractions in the Leichhardt catchment are about 105.7 GL/year(~7% of median annual discharge). However, actual mean annual water use is estimated to beless than half this amount.
•Discounting tailings dams, the Leichhardt catchment contains five dams listed in the AustraliaNational Committee on Large Dams register: Julius Dam (107.5 GL capacity), Leichhardt RiverDam / Lake Moondarra (103 GL capacity), Greenstone Creek / Waggaboonya Lake (Greenstone)
(13.6 GL capacity), East Leichhardt Dam / Lake Mary Kathleen (12.1 GL capacity) and Rifle CreekDam (9.5 GL capacity). With the exception of East Leichhardt Dam, which is now only used forrecreation, the dams supply water for mining, industry and town uses.
•Water quality is variable across the Southern Gulf catchments. Studies in the late 2000s foundthe water quality of the upper Leichhardt River had been influenced by urban and miningactivity and exceeded a number of heavy metal water quality guideline trigger values, howeverthe drinking water source for Mount Isa (Lake Moondarra) was found to meet drinking waterguidelines.


The Gregory River, which flows into the Nicholson River approximately 85 km from the coast, is 
the largest perennial river in semi‑arid Queensland. 

•Lawn Hill Creek and the Gregory and O’Shannassy rivers receive groundwater dischargethroughout the dry season from the CLA, which is composed mostly of the CamoowealDolostone and Thorntonia Limestone.
•On average, approximately 87% of the streamflow in the Southern Gulf catchments occursbetween January and March. In the perennial Gregory River, however, approximately 78% ofstreamflow occurs over the same time period.



The Southern Gulf catchments contain a significant diversity of species and habitats, 
including freshwater, terrestrial and marine habitats of great cultural, conservation and 
commercial importance 

The Southern Gulf catchments are largely intact, but they are not pristine. 

• A range of economic enterprises, infrastructure and human-induced impacts occur in the 
Southern Gulf catchments, and the nature and extent to which these have modified the habitats 
and affected species of the Southern Gulf catchments vary. 
• The near-coastal and estuary habitats of the Southern Gulf catchments support fishing 
industries, including a commercial barramundi fishery, prawns and mud crabs (mainly Scylla 
serrata). 
• In the Leichhardt catchment, Lake Julius and Lake Moondarra are listed in the Directory of 
Important Wetlands in Australia (DIWA). While the water in these two storages predominantly 
supplies urban, mining and industrial demand around Mount Isa and Cloncurry, the permanent 
water provides important dry-season refuge for waterbirds and supports a variety of freshwater 
fish species. 
• In the Southern Gulf catchments, feral horses, wild pigs and cane toads are among the 
introduced animals. 
• Weed species of interest in and around the Southern Gulf catchments include prickly acacia, 
buffel grass, salvinia rubber vine and water hyacinth. 


Floods have economic significance because they underpin the health of the recreational and 
commercial fisheries in the Gulf of Carpentaria, which include a barramundi fishery and the 
Northern Prawn Fishery, which had a catch of prawns worth $85 million in 2019–20. 

• Wet-season flooding inundates significant parts of the lower reaches of the rivers in the 
catchments, connecting wetlands to river channels, inundating floodplains, and allowing the 
exchange of fauna, flora and nutrients, which drives an ecological productivity boom. 
• The 13 DIWA-listed wetlands in the Southern Gulf catchments include a variety of wetland 
types, ranging from estuarine wetlands with salt flats and saltmarshes to artificial lakes and 
spring-fed creeks and rivers. 
• Protected areas located in the Southern Gulf catchments include the UNESCO World Heritage-
listed Australian Fossil Mammal Sites (Riversleigh, Queensland), which is in Boodjamulla 
National Park (Queensland), and Finucane Island National Park (Queensland). There are also 
three Indigenous Protected Areas: Ganalanga‑Mindibirrina, NT; Nijinda Durlga, Queensland; and 
Thuwathu/Bujimulla, Queensland. 
• The marine, near-shore and estuarine environments of the Southern Gulf catchments have 
extensive intertidal flats and estuarine communities, including mangroves, salt flats, coral reefs 
and seagrass habitats. These habitats are highly productive, have high cultural value and include 
many areas of national significance. 
• Seagrass beds in the near-coastal Gulf of Carpentaria have high diversity and grow in vigorous 
stands. They provide important food and habitat for dugongs (Dugong dugon), green sea turtles 
(Chelonia mydas) and prawns (Penaeus spp.). 



• The dominant vegetation types in the catchments are open eucalypt woodlands, Melaleuca 
forests and woodlands, and, on the cracking clay plains, tussock grasslands characterised by the 
Mitchell grasses (Astrebla spp.). 
• The marine and near-shore marine areas of the catchments contain significant habitat for sea 
turtles, shorebirds and seabirds. 
• Protected species include freshwater or largetooth sawfish (Pristis pristis; Vulnerable, EPBC Act) 
and the Gulf snapping turtle (Elseya lavarackorum). 
• The Southern Gulf catchments provide important stopover habitat for migratory shorebird 
species listed under the EPBC Act, including the eastern curlew (Numenius madagascariensis; 
Critically Endangered) and the Australian painted snipe (Rostratula australis; Endangered). 


Indigenous values, rights and development goals 

Indigenous Peoples are a significant and increasing population of the Southern Gulf catchments. 

• Traditional Owners have recognised native title and cultural heritage rights, have Aboriginal 
freehold land ownership and control, or are the custodians of, significant natural and cultural 
resources, including land, water, coastline and sea. 
• Water-dependent fishing and hunting are key health, customary and economic roles for 
Indigenous Peoples in the Southern Gulf catchments. The rivers and underground water support 
food security and good nutrition, and are crucial to geographical and cultural relationships. 
• The history of pre-colonial and colonial patterns of land and natural resource use and 
preservation in the Southern Gulf catchments is important to understanding present 
circumstances. This history has shaped residential patterns, including across the Queensland–NT 
border, and it also informs responses by the Indigenous Peoples to future development 
possibilities. 
• The Indigenous population of the Southern Gulf catchments outside the Mount Isa urban centre 
is 60% of the total population. 


From an Indigenous perspective, ancestral powers are still present in the landscape, including 
underground water, and they intimately connect Peoples, Country and culture. 

• Those powers must be considered in any action that takes place on Country. 
• Patterns of ownership and language affiliation follow features of the landscape and waterways 
and are reflected in the place names and songs of significant Dreamings and totemic figures. 
• Water is central to the cultural landscape. Riverine and aquatic areas are known to be strongly 
correlated with cultural heritage sites. 
• Some current cultural heritage considerations restrict Indigenous capacity to respond to 
development proposals because some knowledge is culturally sensitive and cannot be shared 
with those who do not have the cultural right and authority to know. 


Catchment-wide deliberative processes will be vital to ensuring that Indigenous water rights and 
interests are actively engaged and included in future water-dependent development and 
planning. 


• Indigenous Peoples, especially those in the downstream parts of the catchments, see 
environmental impact assessments as crucial tools to assist them to make decisions about 
water-dependent development. 
• Indigenous Peoples have business and water development objectives designed to create 
opportunities for existing residential populations, including the supply of safe and secure 
community water to residents, and to aid the return of Peoples living elsewhere. 
• Indigenous Peoples want to be owners, partners, investors and stakeholders in any future 
development. This reflects their status as the longest-term residents with deep inter-
generational ties to the catchment. Indigenous custodians in the catchments are engaged in 
diverse collaboration and partnership models with the private, non-government, government 
and research sectors. 


Opportunities for agriculture and aquaculture 

There is about 1,400 ha of irrigated agriculture and 4,000 ha of rainfed agriculture in the 
Southern Gulf catchments. 

Although an abundance of soil is suitable for irrigated agriculture in the Southern Gulf 
catchments, the area that can be irrigated is limited by water. 

• Up to about 5.1 million ha of soils in the Southern Gulf catchments are classified as moderately 
suitable with considerable limitations (Class 3) or better (Class 1 or Class 2) for irrigated 
agriculture, depending on the crop and irrigation method chosen. 
• Class 3 soils have considerable limitations that lower production potential or require more 
careful management than more suitable soils, such as Class 2 soils. 
• About 4.7 million ha of soils in the Southern Gulf catchments are rated as Class 3 or better for 
irrigated pulses (i.e. food legumes) using spray irrigation in the dry season. Most of this area is 
rated as Class 2. In comparison, about 1.7 million ha of soils are rated Class 3 or better using 
furrow irrigation in the dry season for the same crops. 
• About 4.7 million ha of soils in the Southern Gulf catchments are rated as Class 3 or better for 
cotton or grains crops using spray irrigation in the dry season. Under furrow irrigation in the dry 
season, there are about 1.8 million ha of soil suitable for cotton or grain crops, all of which are 
rated as Class 3. 


Bushfoods are an emerging niche industry across northern Australia. Kakadu plum, though not 
recorded as occurring in the Southern Gulf catchments, is one of the best known and has one of 
the most well-developed supply chains. However, most bushfoods continue to be 
wild‑harvested with very little grown commercially. Limited information on commercial 
bushfood operations is publicly available. 

The soils in different parts of the study area are starkly different. 

• The largest arable areas in the Southern Gulf catchments are the self-mulching cracking clay soils 
of the Armraynald Plain (1.03 million ha) and Barkly Tableland (308,000 ha). The cracking clay 
soils are likely to present severe trafficability constraints throughout much of the wet season. 
Irrigation of the Armraynald Plain and Barkly Tableland would be best suited to use of surface 
water and groundwater respectively. 



•Downstream of Doomadgee are large contiguous areas of red sandy and loamy soils suitable forirrigated vegetables (23,000 ha) along the Nicholson River. However, in the absence of a damupstream, on-farm storage of water for broad-scale irrigation would be challenging due to thedifficulty of constructing ringtanks on these sandy soils. These soils are unlikely to be suitable forperennial horticulture due to the risk of flooding. It may be possible to slightly raise and enhancethe existing weir on the Nicholson River near Doomadgee to provide some additional water toirrigate small-scale market gardens either on these sandy and loamy soils or on similar soilscloser to Doomadgee.
•The Leichhardt catchment has opportunities for irrigated horticulture on the friable soils(103,000 ha) on the narrow levees of the Leichhardt River downstream of Kajabbi. Adjacent tothese soils, and up to 1 km from the river, are friable clay soils suitable for broadacre irrigation.
While these heavier soils are suitable for constructing ringtanks, conveying water pumped fromthe Leichhardt River across the sandy levee soils to ringtanks may be costly and inefficient insome locations.


Irrigation enables higher yields and more flexible and reliable production than rainfed 
crops 

•Many annual crops can be grown at most times of the year with irrigation in the Southern Gulfcatchments. Irrigation provides increased yields and flexibility in sowing date.
•Sowing dates must be selected to balance the need for the best growing environment(optimising solar radiation and temperature) with water availability, pest avoidance,
trafficability, crop sequences, supply chain requirements, infrastructure requirements, marketdemand, seasonal commodity prices and, in the case of genetically modified cotton, plantingwindows specified within the cotton industry.
•Irrigated crops likely to be commercially viable with a dry-season planting (late March to August)
include annual horticulture, cotton and mungbean. Irrigated crops likely to be commerciallyviable with a wet-season planting (December to early March) include cotton, forages andpeanuts.
•Seasonal irrigation water applied to crops can vary enormously with crop type (e.g. due tovariations in duration of growth, rooting depth), season of growth, soil type and rainfallreceived. For example, cotton planted in the wet season and dry season requires about 5 ML/haand 6 ML/ha, respectively, of irrigation water in at least 50% of years. A high-yielding perennialforage such as Rhodes grass requires up to about 20 ML/ha each year, averaged across a fullproduction cycle.
•Rainfed cropping is theoretically possible but most likely to be opportunistic in the Southern Gulfcatchments based on rainfall received and stored soil water.How cultivated land is managed inthe years when rainfall is insufficient for rainfed cropping will be crucial for sustainable farmingoperations and the industry’s social licence to operate.


Excess rainfall can also constrain crop production on some soils. 

•High rainfall and possible inundation mean that wet-season cropping on the alluvial clay soils ofthe Armraynald Plain carries considerable risk due to potential difficulties with access topaddocks, trafficability, waterlogging of immature crops and deteriorating water quality where



agricultural runoff is poorly managed.• Accumulation of soil salinity due to irrigation over time 
in these soils is currently unknown and would need to be monitored, especially in the 
imperfectly drained soils on the northern part of the Armraynald Plain. 


Establishing irrigated cropping in a new region (i.e. greenfield development) is challenging. It has 
high input costs, high capital requirements and requires an experienced skills set. 

• For broadacre crops, gross margins of the order of $4,000 per hectare per year are required to 
provide a sufficient return on investment where on-farm development capital costs are about 
$20,000/ha. Crops likely to achieve such a return include cotton and to a lesser extent Rhodes 
grass hay, noting that the gross margins of hay are highly sensitive to local demand, price and 
the transport costs. 
• Horticultural gross margins would have to be higher (of the order of $7,000 to $11,000 per 
hectare per year) to provide an adequate return on the higher capital costs of developing this 
more intensive type of farming (relative to broadacre). Profitability of horticulture is extremely 
sensitive to prices received, so the locational advantage of supplying out-of-season (winter) 
produce to southern markets is critical to viability. Annual horticulture row crops would be the 
most likely to achieve these returns in the Southern Gulf catchments, but would be marginal. 


Growing more than one crop per year may enhance the viability of greenfield irrigation 
development. 

• There are proven benefits to sequentially cropping more than one crop per year in the same 
field in northern Australia, particularly where additional net revenue can be generated from the 
same initial investment in farm development. 
• Numerous options for crop sequences could be considered, but these would need to be tested 
and adapted to the particular opportunities and constraints of the Southern Gulf catchments’ 
soils and climates. While somewhat opportunistic, the most likely sequential farming systems 
could be those combining short-duration crops such as annual horticulture (e.g. melons), 
mungbean, chickpea and grass forages. Following a rainfed wet-season crop with an irrigated 
dry-season crop might also be possible. 
• Trafficability constraints on the alluvial clay soils will limit the options for sequential cropping 
systems. The well‑drained loamy soils on elevated plains near Doomadgee and the friable soils 
adjacent to the Leichhardt River pose fewer constraints for scheduling sowing times and the 
farm operations required for sequencing two crops in the same field each year. Even so, 
sequential cropping systems would be very tight operationally. 
• Tight scheduling requirements mean that even viable crop sequences may be opportunistic. The 
challenges in developing locally appropriate sequential cropping systems, and the management 
packages and skills to support them, should not be under-estimated. 


Irrigated cropping has the potential to produce off-site environmental impacts, although these 
can be mitigated by good management and new technology. 

• The pesticide and fertiliser application rates required to sustain crop growth vary widely among 
crop types. Selecting crops and production systems that minimise the requirement for pesticides 
and fertilisers can simultaneously reduce costs and negative environmental impacts. 



•Refining application rates of fertiliser to better match crop requirements, using controlled-
release fertilisers and improving irrigation management, are effective ways to minimise nutrientadditions to waterways and, hence, the risk of harmful microalgae blooms.
•Adherence to well-established best management practices can significantly reduce erosionwhere intense rainfall and slope would otherwise promote risk. This would also decrease the riskof herbicides, pesticides and excess nitrogen entering the natural environment.
•More than 99% of the cotton grown in Australia is genetically modified. The geneticmodifications have allowed the cotton industry to substantially reduce insecticide (by greaterthan 85%) and herbicide application to much lower levels than previously used. In addition toreducing the likelihood and severity of off-site impacts, genetically modified crops offer healthbenefits to farm workers who handle fewer chemicals. This technology has considerablerelevance to northern Australia.


Irrigated forages can increase the number of cattle sold and the income of cattle enterprises. 
However, the increased income is usually offset by the high initial capital costs and ongoing 
costs of irrigating a forage crop. 

•The dominant beef production system in the Southern Gulf catchments is a cow–calf breedingenterprise, with several markets possible. There is limited fattening of cattle within the studyarea, and many cattle are moved to different parts of Queensland before their final destination.
•While native pastures are generally well adapted to harsh environments, they imposeconstraints on beef production through their low productivity and digestibility and theirdeclining quality through the dry season. Growing irrigated forages and hay would allow higher-
quality feed to be fed to specific classes of livestock to achieve higher production and/ordifferent markets. These species could include perennial grasses, forage crops and legumes.
•Grazing of irrigated forages by young cattle, or feeding them hay, decreases the time they taketo reach sale weight and, in particular, increases their daily weight gain through the dry season.
•While ostensibly simple, there are many unknowns regarding the best way to implement asystem whereby irrigated forages and hay are grown on-farm to augment an existing cattleproduction system.
•Growing forages or hay to feed young cattle for the export market was not financially viable inthe modelled scenarios tested when capital costs were considered.While beef production andtotal income increased, gross margins were reasonably similar to, or less than, baseline cattleoperations.


Pond-based black tiger prawns or barramundi (in saltwater) or red claw crayfish (in fresh 
water) offer potentially high returns 

Along the coastal reaches of the Southern Gulf catchments, approximately 194,000 ha of land is 
suitable for prawn and barramundi aquaculture, using earthen ponds. 

•A large (i.e. 100 ha) pond-based marine culture aquaculture farm typically uses less than 
4 GL/year of freshwater.



•Prawn and barramundi aquaculture elsewhere have proven land-based production practices andwell‑established markets for harvested products. These are not fully established for otheraquaculture species being trialled in northern Australia.
•Prawns could potentially be farmed in either extensive (low-density, low-input) or intensive(higher-density, higher-input) pond-based systems. Land-based farming of barramundi wouldlikely be intensive.
•The most suitable areas of land for pond-based marine aquaculture systems are restricted to theareas of the catchment under tidal influence and the river margins where cracking clay andseasonally or permanently wet soils dominate.
•Annual operating costs for intensive aquaculture are so high that they can exceed the initial costof developing the enterprise. Operational efficiency is therefore the most importantconsideration for new enterprises, particularly the production efficiency in converting feed tosaleable product.


Surface water storage potential 

Indigenous customary, residential and economic sites are usually concentrated along major 
watercourses and drainage lines. Consequently, potential instream dams are more likely to have 
an impact on areas of high cultural significance than are most other infrastructure developments 
of comparable size. 

•Complex changes in habitat resulting from inundation could create new habitat to benefit somespecies, while other species could experience a negative impact through loss of habitat.


Many of the upland regions of the Southern Gulf catchments are topographically and 
geologically favourable for large instream dams. However, the semi-arid climate and small 
catchment areas would result in most potential dam sites being relatively low yielding. 


•The most cost-effective potential dam sites in the Southern Gulf catchments are on the Gregory 
River and Gunpowder Creek. In the 1960s and 1970s, the Queensland Water Supply 
Commission investigated potential dam sites on both drainage lines.
•Potential dam sites on the Gregory River at natural constrictions upstream of the township of 
Gregory are the highest yielding and most cost-effective due to the large streamflow and 
proximity to large contiguous areas of black and grey cracking clay soils of the Armraynald Plain. 
The topography, sloping away from the Gregory River, enables cheap gravity-based methods of 
distributing water.
•A hypothetical dam on the Gregory River upstream of Gregory with a reservoir full supply level 
such that it does not extend into the Boodjamulla National Park could yield 133 GL in 85% of 
years and cost $683 million (−20% to +50%) to construct, assuming favourable geological 
conditions. This would be sufficient water to support approximately 10,000 ha of dry-season 
cropping under surface irrigation, with the reticulation infrastructure costing approximately 
$38 million, or $3,800 per hectare of irrigated land.
•A previous study found that residents of Mount Isa place high value on particular rivers. The 
Gregory River, being one of the few perennial rivers in north‑west Queensland, has a high value 
to Indigenous and non‑Indigenous residents.



•A hypothetical dam on Gunpowder Creek could potentially yield 119 GL in 85% of years and cost$773 million. If used for agriculture, the nearest suitable soils are approximately 35 kmdownstream near the junction of Gunpowder Creek and the Leichhardt River. This would besufficient to irrigate approximately 11,000 ha of dry-season broadacre and horticultural cropsunder spray irrigation. However, the grade of the land and the sandy texture of the surface soilsmean that water would need to be piped from the river, greatly increasing the cost ofreticulation infrastructure (estimated to be about $320 million or $29,000 per hectare ofirrigated land).
•The higher cost of the irrigation schemes associated with a potential dam at Gunpowder Creekcompared to the potential site on the Gregory River mean that high‑value annual horticulturewould need to be grown on the friable soils downstream of the former site to offset the highercosts, assuming there was a market for the produce.
•Although there are some potential dam sites on the Nicholson River, this part of the study areais particularly remote, greatly increasing capital and ongoing costs.


On-farm water storages may have more prospects of being commercially viable than large 
instream dams in the Southern Gulf catchments. 

•Suitably sited large farm-scale gully dams are a relatively cost-effective method of supplyingwater. Although most sites are located in the uplands, where the soil is rocky and shallow andless suitable for their construction and irrigated agriculture, some locations – such as thenorth‑western part of Settlement Creek, Mornington Island, the lower Leichhardt River andupper parts of Morning Inlet – have a coincidence of topography and soils that is favourable forgully dams and irrigated agriculture.


The alluvial clay soils on the Armraynald Plain offer different opportunities and risks to the 
loamy soils near Doomadgee. 

•Approximately 21% of the Southern Gulf catchments has soils that are likely to be suitable forthe construction of ringtanks. The most promising areas are the cracking clay soils of theArmraynald Plain east of the Gregory River and downstream of Gregory, where the natural slopeaway from the river enables the cost-effective conveyance of water using gravity.
•Except for in the lower reaches of the Nicholson River, the soils of the Nicholson catchment aregenerally too sandy for ringtanks. The Leichhardt River downstream of Kajabbi has soils suitablefor ringtanks; however, sandy levees adjacent to the river can be up to 1 km wide, increasingconveyance costs and/or losses. Further downstream, although the soils are suitable forringtanks adjacent to the Leichhardt River, to the west the land slopes towards the river, whichwould result in additional pumping costs.
•With water harvesting it is physically possible to extract 150 GL of water in 75% of years,
assuming an even split between the Nicholson and Leichhardt catchments, without havingimpacts on the reliability of water supply to existing licensed users. This quantity of water issufficient to irrigate about 12,000 ha of broadacre crops during the dry season by pumping ordiverting water and storing it in offstream storages such as ringtanks. This would result inreductions in the mean and median annual discharges to the Gulf of Carpentaria from theNicholson and Leichhardt catchments of about 3% and 5%, respectively.



Energy infrastructure constraints are a key consideration for energy‑intensive 
enterprises in the Southern Gulf catchments 

•Mount Isa and immediate surrounds are provided power by the North West Power System.
•As a grid isolated from the rest of the Queensland electricity grid, the availability of generationon the North West Power System is largely matched to the existing demand of the major miningcustomers. Dispatch protocols may place limits on availability of power to new large retailcustomers, such as a large irrigation development.
•Capacity on the existing Ergon 220kV transmission line that runs from Mount Isa to CenturyMine is limited, and new developments would need to negotiate with both Ergon and majorcustomers on the line to obtain the required energy and capacity.
•New energy-intensive enterprises would require development of dedicated electricaldistribution infrastructure such as new substations and distribution lines.
•CopperString 2032 will connect the North West Power System to the National Electricity Market,
alleviating any constraints in generation. However, constraints in the transmission anddistribution system would remain.


Development of a large in-river storage solely for hydro-electric power purposes would 
not be commercially feasible in the Southern Gulf catchments. 

Other existing and potential industries that depend on water 

Mining 

The Southern Gulf catchments fall within the North West Minerals Province, which is considered 
to be one of the world’s most significant areas for producing base and precious metals. Mining is 
by far the largest industry in the study area and has an annual value more than 100 times that of 
grazing. 

•Mining provides about 28% of all jobs in the Southern Gulf catchments.
•Mount Isa is in a period of transition, with major lead, copper and zinc mines in the regionrecently closing or scheduled to cease operations imminently. However, technological advances(e.g. batteries, super magnets, electronics, medical imaging) have resulted in increased demandfor rare earth elements. These are referred to as critical minerals and strategic materials, andthe NT and Queensland governments have programs to attract investment in exploration andinfrastructure.
•Occurrences of critical minerals and strategic materials have been recorded in the Southern Gulfcatchments, and mineral and petroleum exploration leases cover 67% of the study area. Futuredemand for minerals is highly speculative.


Across Australia, mining uses about one-tenth of the water used by irrigated agriculture, though 
water for mining is assigned a higher reliability than agriculture, which makes water use 
comparisons difficult. 


•The amount of water used for mining is highly variable depending upon a wide range of factors,
including mining methods, ore types, ore grades and processing treatments. With the exceptionof coal mines, which are not found in the Southern Gulf catchments, and large gold mines,
individual mines typically use less than 0.5 GL/year.
•Many uses of water by mining enterprises (e.g. dust suppression, cooling, slurry and processwater) do not require the water to be of potable quality.
•Because water is typically a very small fraction of the total input cost of a mine, and miningproduces high‑value products, mining enterprises have the capacity to develop their own watersupplies. In the Southern Gulf catchments, the historical concentration of mining, industrial andurban activity around Mount Isa resulted in sufficiently high water demand for the constructionof large, purpose-built reservoirs.
•Recent water use from existing reservoirs in the Mount Isa region is estimated to be modestrelative to total supplemented entitlements (<35%), indicating that the existing dams havescope to supply water for a modest expansion of mining, depending upon the location ofpotential mines.
•There is limited scope for existing or new dams in the Southern Gulf catchments to be used forboth mining and irrigated agriculture because high-value minerals are located in areas with hardrock, which tend to be distant from large contiguous areas of soil suitable for irrigatedagriculture, such as alluvial plains.


Petroleum extraction and de-watering of mine pits produce water that needs to be treated and 
appropriately disposed. 

Tourism 

The Southern Gulf catchments have a highly seasonal and relatively low volume of visitation, 
largely due to their climate, remoteness, sparse population and limited tourism development. 

•Annual visitation to the study area is estimated to result in approximately $150 millionexpenditure. Most visitors go to Mount Isa, and a large proportion (~60%) of visitors travelling toMount Isa are on business (which cannot be separated in the visitation statistics).
•Although tourism in northern Australia consumes very small quantities of water relative to otherindustries, the state of northern Australia’s tourism economy is closely tied to the state andperceived attractiveness of its ecosystems, including its rivers and water‑dependent ecosystems.
•Self-drive is the predominant tourism market, representing 87% of visitors to outbackQueensland. Many self-drive visitors are motivated by experiencing an ancient, vast and ‘empty’landscape with opportunities for exploration and solitude.
•With a large proportion of the Southern Gulf catchments in a relatively ‘undisturbed’ state,
there is potential for growth in nature-based tourism, particularly as Mount Isa’s airportprovides a commercial gateway to the region and critical infrastructure that many other parts ofnorthern Australia lack. However, the remoteness of the region and lack of supportinginfrastructure beyond Mount Isa considerably constrain tourism’s potential, as does the highseasonality of visitation, which limits enterprise profitability and year-round employmentopportunities.



•Much of the appeal of the Southern Gulf catchments to self-drive tourists is likely to be theabsence of human and commercial infrastructure, so development that alters the region’scurrent characteristics could be either appealing or alienating to current tourist markets.


While water resource development for agriculture has the potential to negatively affect tourism 
opportunities in the Southern Gulf catchments, some developments and associated supporting 
infrastructure (e.g. roads, accommodation) may, conversely, present opportunities to foster 
tourism growth. 

•Lake Argyle in the east Kimberley region (WA) developed as an irrigation dam to supply the OrdRiver Irrigation Area. It is now advertised as one of WA’s most spectacular attractions, offering awide range of tourism activities. Studies have identified that Lake Argyle is perceived by visitorsin a similar fashion to some ‘natural’ local attractions such as billabongs. The cultivated land ofthe Ord River Irrigation Area, however, is reportedly perceived by visitors differently, as being‘domesticated’.
•Due to the presence of Lake Moondarra and Lake Julius, the recreational value of additionaldams near Mount Isa is unlikely to make a discernible impact on the local economy, thoughdams in more remote regions of the Southern Gulf catchments could encourage self-drivetourists to stay in those regions longer.
•Tourism has the potential to enable economic development within Indigenous communitiesbecause Indigenous tourism enterprises, which are usually micro businesses, often havecompetitive advantages.
•While tourism offers economic and employment opportunities, it can also cause impacts such asclearing of vegetation and environmental damage due to foot, bike or vehicle traffic. This canreduce amenity for local residents and increase risks such as the potential for the spread ofweeds, pests, or root rot fungus.


The Southern Gulf catchments have productive groundwater systems 

Groundwater systems in the Southern Gulf catchments are poorly studied. Nonetheless, it is 
estimated that they could potentially supply up to approximately 40 GL of water per year in 
addition to the 3.5 GL/year of existing licensed entitlements, depending on community and 
government acceptance of impacts to groundwater-dependent ecosystems (GDEs) and existing 
groundwater users. 

•Not all of this water could be used for irrigated agriculture, due to poor water quality, distanceto suitable soil, and/or low bore yields.• The most promising groundwater resource in theSouthern Gulf catchments is the regional-scale Cambrian Limestone Aquifer (CLA), which ismostly comprised of the Camooweal Dolostone and Thorntonia Limestone. With appropriatelysited groundwater borefields, it is physically possible that multiple small- to intermediate‑scale(1 to 3 GL/year) groundwater-based enterprises could extract approximately 10 to 20 GL/year ofwater from the CLA, depending on community and government acceptance of impacts to GDEsand existing groundwater users.
•The mean annual recharge across the CLA within the Southern Gulf catchments is estimated tobe approximately 160 GL. The conservative mean annual recharge is estimated to be between40 and 80 GL.



•The CLA outcrops along the south-western part of the Southern Gulf catchments. Groundwaterdischarge from the aquifer occurs from ecologically and culturally important springs and pointsof lateral outflow where the streams are incised into the CLA along Lawn Hill Creek and theGregory and O’Shannassy rivers.
•Groundwater from the CLA varies from very fresh (<500 mg/L total dissolved solids (TDS)) tobrackish (<3,000 mg/L TDS), which is towards the upper limit of salinity for most crops.


The regional-scale Gilbert River Aquifer (GRA) within the geological Carpentaria Basin underlies 
the central and northern parts of the study area. 

•The GRA does not outcrop within the Southern Gulf catchments, so there is no direct rechargeto this aquifer within the study area. Recharge predominantly occurs as lateral inflow ofgroundwater from the east of the Leichhardt catchment boundary.
•With appropriately sited groundwater borefields, it is possible that multiple small- tointermediate-scale (1 to 3 GL/year) developments could extract up to approximately 5 GL/yearfrom the GRA.
•The GRA is shallowest (<250 m below ground level (mBGL)) at its south-western basin margin inthe mid‑reaches of the study area. It hosts some fresh water (<1,000 mg/L TDS) in places alongits south-western margin between Settlement Creek and the Leichhardt River. The GRAincreases in depth in a north-east direction towards the coast (>400 mBGL), and the waterbecomes increasingly brackish (>2,000 mg/L TDS), presenting economic challenges forgroundwater infrastructure.
•The GRA becomes artesian approximately 20 to 50 km from its southern basin margin, andartesian conditions extend into the Gulf of Carpentaria.
•Potential opportunities for future groundwater resource development are likely to be limitednear existing licensed groundwater users, such as the communities of Burketown and Gununa,
where the GRA is at depths of greater than 500 mBGL. Neither licence is currently in use, due tothe naturally poor water quality of the aquifer.
•It is unknown whether the GRA contributes groundwater to springs and seeps within the studyarea, though it is unlikely, given the depth of the aquifer.


Collectively, other groundwater systems in the Southern Gulf catchments may yield 
approximately 15 GL/year. 


•The Cenozoic alluvial aquifers in the mid- to lower reaches of the Nicholson, Gregory and 
Leichhardt rivers, and Settlement Creek and its tributaries, host local-scale groundwater 
systems. However, data are very sparse, and these water resources remain poorly understood. 
Imagery of the study area appears to indicate that alluvial material is more laterally extensive 
than found elsewhere in northern Australia.
•Alluvial aquifers have potential for multiple small-scale (<0.5 GL/year) localised developments or 
as a conjunctive water resource where surface water is available. Opportunities are likely to be 
limited where the saturated thickness of the aquifer is thin (<10 m), as well as in areas within 
1 km of the prescribed watercourses of the Nicholson, Gregory and Leichhardt rivers. Impacts 
on local GDEs would need to be evaluated, because streamflow and persistent waterholes in 
some rivers are potentially supported by groundwater discharge from the alluvium.



•The sparse groundwater data available for the alluvial aquifers suggest that the groundwaterquality in these systems is good (<600 mg/L TDS) in places.
•Fractured and weathered rock aquifers are hosted in a variety of Proterozoic rocks across thesouthern, central and northern parts of the study area. These aquifers are highly variable incomposition and water quality, and typically groundwater bores yield little water (<2 L/s).
Where these aquifers occasionally exhibit higher yields, due to extensive fracturing and jointing,
they are often storage limited.


There is potential to undertake managed aquifer recharge in aquifers of the Cenozoic alluvium 
and in the CLA. 

•The most promising aquifers for infiltration-based managed aquifer recharge in the Southern 
Gulf catchments are aquifers within the Cenozoic alluvium, which is associated with many of 
the major rivers in the study area. However, there are few bore logs and limited groundwater‑level information available for the Cenozoic alluvium, and it is likely the opportunity for MAR 
may vary between locations. If an alluvial aquifer is found to be suitable for MAR, it will be more 
cost-effective to extract groundwater in the first instance.


Changes in volumes and timing of river flows have ecological impacts 


•Although irrigated agriculture occupies only a small percentage of the landscape, relatively small 
areas of irrigation can use large quantities of water, and the resulting changes in the flow regime 
can have profound effects on flow-dependent flora and fauna and their habitats.
•Changes in river flow may extend considerable distances downstream and onto the floodplain, 
including into the marine environment, and their impacts can be exacerbated by other changes, 
including changes to connectivity, water quality and invasive species. The magnitude and spatial 
extent of ecological impacts arising from water resource development are highly dependent on 
the type of development, location, timing, extraction volume and mitigation measures 
implemented.
•Ecological impacts, inferred here by calculating change in ecological flow dependency for a range 
of fresh water–dependent ecological assets for the Nicholson and Leichhardt catchments, 
increases non-linearly with increasing scale of surface water development (i.e. large instream 
dams and water harvesting). A change in ecological flow dependency does not necessarily 
correlate to change in ecological condition. Change in ecological condition varies between assets 
depending on the importance of river flow to each asset’s condition and other drivers (e.g. 
rainfall, local runoff, groundwater).
•At equivalent levels of water resource development (i.e. in terms of volume of water extracted), 
and without mitigation measures the mean impact on surface‑flow‑dependent ecology of an 
instream dam on a major tributary of the Leichhardt River was found to be less than water 
harvesting averaged across the Leichhardt catchment. The mean impact of an instream dam on 
the Gregory River averaged across the Gregory –Nicholson catchment was found to be larger 
than water harvesting.
•Mud crabs, mullet, threadfin and prawn species are among the ecological assets most affected 
by flow changes for water harvesting. However, different types of development affected assets 
differently.



•Water harvesting developments extracting a total of 50 to 300 GL/year of water from the 
Nicholson and Leichhardt catchments without mitigation strategies resulted in minor and 
negligible changes to ecology flow dependencies of freshwater assets when averaged across 
each catchment respectively. Local impacts below points of extraction, however, were generally 
moderate for freshwater assets at the higher extraction volumes and generally minor for 
near-shore marine assets at higher extraction volumes.


Mitigation strategies that protect low flows and first flows of a wet season are successful in 
reducing impacts on ecological assets. These can be particularly effective if implemented for 
water harvesting developments. 

•At equivalent volumes of water extraction, imposing an end-of-system (EOS) annual flowrequirement, where water harvesting can only commence after a specified volume of water hasflowed past the EOS and into the Gulf of Carpentaria, is an effective mitigation measure forwater harvesting. However, the efficacy of this mitigation measure is reduced with a pump-startthreshold of 600 ML/day, as is required to ensure there are no impacts on existing consumptivewater users.
•The additional impact caused by water harvesting developments extracting 150 GL/year andwith a pump-start threshold of 600 ML/day is less across most ecological assets than the impactof existing levels of development and use compared with pre‑European development.
•A dry future climate has the potential to have a larger mean impact on ecological flowdependencies across the Nicholson and Leichhardt catchments than the largest physicallyplausible water resource development scenarios. However, the perturbations to flow arisingfrom a combined drier future climate and water resource development result in greater impactson ecology flow dependency than either factor on their own.


For instream dams, location matters, and there is potential for high risks of local impacts. 
Improved outcomes are associated with maintaining attributes of the natural flow regime. 

•Potential dams may result in an extreme change in the ecological flow dependency of someassets immediately downstream of the dam. However, impacts reduce downstream with theaccumulation of additional tributary flows, so when averaged over the entire catchment ormeasured at the EOS, the change in ecological flow dependency is minor.
•Providing translucent flows (flows allowed to ‘pass through’ the dam for ecological purposes)
improves flow regimes for ecology, particularly for perennial rivers like the Gregory River. Itdoes, however, reduce the yield from the dam’s reservoir.


But it is not just flow, other impacts and considerations are also important. 

•At catchment scales, the direct impacts of irrigated agriculture on the terrestrial environmentare relatively small. However, indirect impacts such as weeds, pests and landscapefragmentation may be considerable, particularly in riparian zones.
•Loss of connectivity associated with new instream structures and changes in low flows may limitmovement patterns of many species within the catchment.



Inefficient farm practices, poorly managed irrigation outflows and uncontrolled runoff from 
irrigation areas close to drainage lines may have a larger impact on ecological condition than 
likely changes in river flow patterns and volume in the Southern Gulf catchments. 

•Nitrogen, phosphorus and potassium are the three primary nutrients used in agriculturalfertilisers. Irrigation outflows and tailwater runoff from irrigation events can be high in thesenutrients as well as in pesticides, herbicides and total dissolved solids.
•If best practice is not followed, the concentrations of these contaminants can be elevated inreceiving surface water and groundwater bodies. However, the extent to which irrigatedagriculture affects the quality of receiving waters is highly variable. It depends on a wide rangeof factors, including crop type, farm management and mitigation measures, type and scale ofdevelopment, water application method, proximity to drainage lines and environmental factorssuch as climate, soil type, topography, hydrogeochemistry and susceptibility of irrigated land toflooding.
•Studies in parts of Queensland with a seasonal hydrology have found that first-flow eventsfollowing irrigation or rainfall play a critical role in determining water quality. Studies haveshown that pesticide concentrations in furrow irrigation runoff are highest following initialirrigation events and decrease in subsequent events.
•When pesticide application rates are managed well and irrigation schedules are aligned withcrop growth stages, the concentration of pesticides in receiving waters is typically low, studies inthe Ord River Irrigation Area have found.
•Vegetated areas can intercept agricultural runoff, reducing pesticide concentrations in surfacewaters approximately three times more than areas of bare soil. This highlights the importance ofmaintaining a wide riparian buffer zone.
•Water quality issues will be most significant closest to the source of the contaminant, because ofdilution and naturally occurring processes by which aquatic systems can partially processcontaminants and regulate water quality. Such processes include denitrification of nitrogen andmicrobial degradation and ultraviolet photolysis of pesticides. There are no equivalent naturalprocesses for reducing phosphorus.


Commercial viability and other considerations 

The total annual economic value of irrigated agriculture in the Southern Gulf catchments has the 
potential to increase substantially, from less than $1 million to over $190 million. 

•The estimated total annual gross value of agricultural production in the Southern Gulfcatchments in 2020–21 was $243.6 million. Livestock commodities accounted for most of this,
and cropping accounted for only $0.9 million.
•Agriculture is a relatively small employer in the Southern Gulf Catchments; it is not listed in thetop five industries of employment.





Large dams could be marginally viable if public investors accepted a 3% discount rate or partial 
contributions to water infrastructure costs, similar to established irrigation schemes in other 
parts of Australia. 

•On-farm water storages provide better prospects and, where sufficiently cheap waterdevelopment opportunities can be found, could likely support viable broadacre farms andhorticulture with low development costs.
•Proponents of large infrastructure projects have a systematic tendency to substantially underestimate development costs and risks and to over estimate the scale and rate at which benefitswill be achieved. This Assessment provides information on realistic unit costs and demandtrajectories to allow potential irrigation developments to be benchmarked and assessed on alike-for-like basis.
•The viability of irrigated developments would be determined by: (i) markets and supply chainsthat can provide a sufficient price, scale and reliability of demand, (ii) farmers’ skills in managingthe operational and financial complexity of adapting crop mixes and production systems suitedto the environments of the Southern Gulf catchments, (iii) the nature of water resources interms of the volume and reliability of supply relative to optimal planting windows, (iv) thenature of the soil resources and their proximity to supply chains, and (v) the costs needed todevelop those resources and grow crops compared with alternative locations.


It is prudent to stage developments to manage financial risk and to allow small‑scale trialling on 
new farms. 

•Farm productivity is subject to a range of risks, and setbacks that occur early have the greatesteffect on a development’s viability. A period of initial underperformance must be anticipated forestablishing greenfield farming in a new location, and this must be planned for.
•There is a strong incentive to start any new irrigation development with well-established andunderstood crops, farming systems and technologies, and to incorporate lessons fromagricultural development elsewhere in northern Australia. Local experience and experience fromthe neighbouring Flinders catchment, complemented by learnings from long-establishedirrigation schemes such as the Ord River Irrigation Area and the Burdekin Haughton WaterSupply Scheme, would provide some guidance.
•New agricultural developments in the study area are likely to start irrigating broadacre cropsand pastures on heavier clay soils before progressing to higher-value and more costlyenterprises such as horticulture on sandy and loamy soils.
•Staging allows ‘learning by doing’ at a small scale, where risks can be contained while testinginitial assumptions of costs and benefits and while farming systems adapt to unforeseenchallenges in local conditions.





Irrigated agriculture has a greater potential than rainfed production to generate economic and 
community activity. 

•Studies in the southern Murray–Darling Basin have shown that irrigation generates a level ofeconomic and community activity that is three to five times higher than would be generated byrainfed production.
•Irrigated developments can unlock the economies of scale for supply chains and support servicesthat allow rainfed farming to establish more easily around the irrigated core.
•A large proportion of increased economic activity during the construction phase of potentialirrigation developments in the Southern Gulf catchments would be expected to leak outside thestudy area. Assuming $250 million in capital costs, which could potentially enable 10,000 ha ofirrigated agriculture (~20 new farm-scale developments with on-farm water sources) the totalregional economic activity within the Southern Gulf catchments associated with the constructionphase would be approximately $200 million (assuming 50% leakage out of the study area).
Additional benefits would flow to other regions, including Townsville, Brisbane and potentiallysome areas outside Queensland and the NT.
•The total annual increased economic activity (direct and indirect) from 10,000 ha of irrigatedmixed broadacre (85%) and horticulture (15%) agriculture in the Southern Gulf catchments couldpotentially amount to $190 million, supporting up to 360 full‑time‑equivalent jobs.
••Based on economic data for North West Queensland, the additional income that flowed toIndigenous households from beef cattle developments was about 5% of that which flowed tonon-Indigenous households. For aquaculture, forestry and fishing together the figure was about2.5% and for mining about 6%. The additional income that flowed to Indigenous householdsfrom other agricultural developments (excluding beef) was about 1.5% of that which flowed tonon-Indigenous households. This indicates that, if agricultural developments in the SouthernGulf catchments are to equally benefit Indigenous and non‑Indigenous households, concertedaction will need to be taken by all stakeholders, including government, industry groups andproponents.


Sustainable irrigated development requires resolution of diverse stakeholder values and 
interests. 

•Establishing and maintaining a social licence to operate is a precondition for substantialirrigation development.
•The geographic, institutional, social and economic diversity of stakeholders increases theresources required to develop a social licence and reduces the size of the ‘sweet spot’ in which asocial licence can be established.
•Key interests and values that stakeholders seek to address include the purpose and beneficiariesof development, the environmental conditions and environmental services that developmentmay alter, and the degree to which stakeholders are engaged.





The Southern Gulf Water Resource Assessment Team 

Project Director 

Chris Chilcott 

Project Leaders 

Cuan Petheram, Ian Watson 

Project Support 

Caroline Bruce, Seonaid Philip 

Communications 

Emily Brown, Chanel Koeleman, Jo Ashley, Nathan Dyer 

Activities 

Agriculture and socio-
economics 

Tony Webster, Caroline Bruce, Kaylene Camuti1, Matt Curnock, 
Jenny Hayward, Simon Irvin, Shokhrukh Jalilov, Diane Jarvis1, Adam Liedloff, 
Stephen McFallan, Yvette Oliver, Di Prestwidge2, Tiemen Rhebergen, 
Robert Speed3, Chris Stokes, Thomas Vanderbyl3, John Virtue4 

Climate 

David McJannet, Lynn Seo 

Ecology 

Danial Stratford, Rik Buckworth, Pascal Castellazzi, Bayley Costin, 
Roy Aijun Deng, Ruan Gannon, Steve Gao, Sophie Gilbey, Rob Kenyon, 
Shelly Lachish, Simon Linke, Heather McGinness, Linda Merrin, 
Katie Motson5, Rocio Ponce Reyes, Jodie Pritchard, Nathan Waltham5 

Groundwater hydrology 

Andrew R. Taylor, Karen Barry, Russell Crosbie, Margaux Dupuy, 
Geoff Hodgson, Anthony Knapton6, Stacey Priestley, Matthias Raiber 

Indigenous water 
values, rights, interests 
and development goals 

Pethie Lyons, Marcus Barber, Peta Braedon, Petina Pert 

Land suitability 

Ian Watson, Jenet Austin, Bart Edmeades7, Linda Gregory, Ben Harms10, 
Jason Hill7, Jeremy Manders10, Gordon McLachlan, Seonaid Philip, 
Ross Searle, Uta Stockmann, Evan Thomas10, Mark Thomas, Francis Wait7, 
Peter Zund 

Surface water hydrology 

Justin Hughes, Matt Gibbs, Fazlul Karim, Julien Lerat, Steve Marvanek, 
Cherry Mateo, Catherine Ticehurst, Biao Wang 

Surface water storage 

Cuan Petheram, Giulio Altamura8, Fred Baynes9, Jamie Campbell11, 
Lachlan Cherry11, Kev Devlin4, Nick Hombsch8, Peter Hyde8, Lee Rogers, 
Ang Yang 



Note: Assessment team as at September, 2024. All contributors are affiliated with CSIRO unless indicated otherwise. Activity Leaders are 
underlined. 

1James Cook University; 2DBP Consulting; 3Badu Advisory Pty Ltd; 4Independent contractor; 5 Centre for Tropical Water and Aquatic Ecosystem 
Research. James Cook University; 6CloudGMS; 7NT Department of Environment, Parks and Water Security; 8Rider Levett Bucknall; 9Baynes Geologic; 
10QG Department of Environment, Science and Innovation; 11Entura 


Acknowledgements 

A large number of people provided a great deal of help, support and encouragement to the 
Southern Gulf Water Resource Assessment (the Assessment) team over the past three years. Their 
contribution was generous and enthusiastic and we could not have completed the work without 
them. 

Each of the accompanying technical reports (see Appendix A) contains its own set of 
acknowledgements. Here we acknowledge those people who went ‘above and beyond’ and/or 
who contributed across the Assessment activities. The people and organisations listed below are in 
no particular order. 

The Assessment team received tremendous support from people in the NT Government, 
Queensland Government and associated agencies. They are too numerous to all be mentioned 
here but they not only provided access to files and reports, spatial and other data, information on 
legislation and regulations, groundwater bores and answered innumerable questions but they also 
provided the team with their professional expertise and encouragement. For the NT – Sally 
Heaton, Lauren Cooper, Brad Sauer, Nathaneal Mills, Brett Herbert, Rob Williams and Nerida 
Horner. For Queensland – Greg Mason, Michael Reid, Geoffrey Cahill, Graham Herbert, Ceri 
Pearce, Enrico Perotti, Michelle Smith, Wayne Vogler, Hayden Ferguson and Neale Searle. 

The Assessment acknowledges the staff of the Carpentaria Land Council Aboriginal Corporation 
who guided consultations and provided valuable assistance to plan and execute the on-ground 
meetings with the board members of the Prescribed Body Corporate entities it represents and 
services. It also acknowledges advice provided by staff of other Prescribed Body Corporate entities 
in the upper sections of the Southern Gulf catchments that influenced the focus of the 
Assessment.” 

A number of people in private industry, universities, local government and other organisations 
also helped us. They include Ernie Camp, Mark Thyer, Rob Worlein, Belinda Worlein, William 
Weaver and Craig Cahill. Land managers and landholders at several properties provided 
hospitality, support and information. They include Lorraine, Wernadinga, Cliffdale and Floraville. 

Our documentation, and its consistency across multiple reports, were much improved by a set of 
copy-editors and Word-wranglers who provided great service, fast turnaround times and patient 
application (often multiple times) of the Assessment’s style and convention standards. They 
include Joely Taylor, Margie Beilharz, Jeanette Birtles and Sally Woollett. Greg Rinder provided 
graphics assistance. 

Colleagues in CSIRO, both past and present, provided freely of their time and expertise to help 
with the Assessment. This was often at short notice and of sufficient scale that managing their 
commitment to other projects became challenging. The list is long, but we’d particularly like to 
thank (in no particular order) Tony Zhen, Ali Wood, Nikki Dumbrell, Daniel Grainger, Veronica 
Hannan, Mahdi Montazeri, Ash Shokri, Zaved Khan, Kellie Muffatti, Carmel Pollino, Sonja Serbov, 
Jai Vaze, Francis Chiew, Heather Stewart, Dilini Wijeweera, Jordan Marano, Juliet Morris, Tenneal 
Maskell, Rachel Harm, Jodie Hayward, Heather Stewart, June Chin, Christian Lawrence, Gillian 


Foley, Anne Freer, Sharon Hall, Sonja Heyenga, Amy Edwards, Sally Tetreault Campbell, Larissa 
Sherman, Phil Davies, Anna Rorke and Amy Nicholson. 

This project was funded through the National Water Grid’s Science Program, which sits within the 
Department of Climate Change, Energy, the Environment and Water. Staff in the Science Program 
supported the smooth administration of the Assessment despite the many challenges that arose 
during the project years. 

A long list of expert reviewers provided advice that improved the quality of our methods report, 
the various technical reports, the catchment report and the case study report. The Governance 
Committee and Steering Committee (listed on the verso pages) provided important input and 
feedback into the Assessment as it progressed. 

Finally, the complexity and scale of this Assessment meant that we spent more time away from 
our families than we might otherwise have chosen. The whole team recognises this can only 
happen with the love and support of our families, so thank you. 

 

Some of the CSIRO staff involved in field work in northern Australia water resource assessments who applied their 
experience to the Southern Gulf analyses 

Photo: CSIRO – Nathan Dyer 

 



Contents 

Director’s foreword .......................................................................................................................... i 
Key findings for the Southern Gulf catchments .............................................................................. ii 
Overview of the Southern Gulf catchments ....................................................................... vi 
Indigenous values, rights and development goals .............................................................. x 
Opportunities for agriculture and aquaculture .................................................................. xi 
Other existing and potential industries that depend on water....................................... xvii 
The Southern Gulf catchments have productive groundwater systems .......................... xix 
Changes in volumes and timing of river flows have ecological impacts .......................... xxi 
Commercial viability and other considerations .............................................................. xxiii 
The Southern Gulf Water Resource Assessment Team .............................................................. xxvi 
Acknowledgements .................................................................................................................... xxvii 
Part I Introduction and overview 1 
1 Preamble ............................................................................................................................. 2 
1.1 Context .................................................................................................................. 2 
1.2 The Southern Gulf Water Resource Assessment .................................................. 4 
1.3 Report objectives and structure ............................................................................ 9 
1.4 Key background ................................................................................................... 12 
1.5 References ........................................................................................................... 16 
Part II Resource information for assessing potential development opportunities 18 
2 Physical environment of the Southern Gulf catchments ................................................. 19 
2.1 Summary .............................................................................................................. 20 
2.2 Geology and physical geography of the Southern Gulf catchments ................... 22 
2.3 Soils of the Southern Gulf catchments ................................................................ 31 
2.4 Climate of the Southern Gulf catchments ........................................................... 46 
2.5 Hydrology of the Southern Gulf catchments....................................................... 60 
2.6 References ........................................................................................................... 94 
3 Living and built environment of the Southern Gulf catchments .................................... 101 
3.1 Summary ............................................................................................................ 102 
3.2 Southern Gulf catchments and their environmental values ............................. 106 
3.3 Demographic and economic profile .................................................................. 133 
3.4 Indigenous values, rights, interests and development goals ............................ 169 
3.5 Legal and policy environment ........................................................................... 182 
3.6 References ......................................................................................................... 186 
Part III Opportunities for water resource development 205 
4 Opportunities for agriculture in the Southern Gulf catchments .................................... 206 
4.1 Summary ............................................................................................................ 207 
4.2 Land suitability assessment ............................................................................... 212 
4.3 Crop and forage opportunities in the Southern Gulf catchments .................... 217 
4.4 Crop synopses .................................................................................................... 245 
4.5 Aquaculture ....................................................................................................... 279 
4.6 References ......................................................................................................... 292 
5 Opportunities for water resource development in the Southern Gulf catchments ...... 296 
5.1 Summary ............................................................................................................ 297 
5.2 Introduction ....................................................................................................... 301 
5.3 Groundwater and subsurface water storage opportunities ............................. 302 
5.4 Surface water storage opportunities ................................................................ 323 
5.5 Water distribution systems – conveyance of water from storage to crop ....... 366 
5.6 References ......................................................................................................... 373 
Part IV Economics of development and accompanying risks 378 
6 Overview of economic opportunities and constraints in the Southern Gulf catchments 
........................................................................................................................... 379 
6.1 Summary ............................................................................................................ 380 
6.2 Introduction ....................................................................................................... 381 
6.3 Balancing scheme-scale costs and benefits ...................................................... 383 
6.4 Cost–benefit considerations for water infrastructure viability ......................... 399 
6.5 Regional-scale economic impact of irrigated development ............................. 408 
6.6 References ......................................................................................................... 414 
7 Ecological, biosecurity, off-site and irrigation-induced salinity risks ............................. 417 
7.1 Summary ............................................................................................................ 418 
7.2 Introduction ....................................................................................................... 422 
7.3 Ecological implications of altered flow regimes ................................................ 424 
7.4 Biosecurity considerations ................................................................................ 451 
7.5 Off-site and downstream impacts ..................................................................... 467 
7.6 Irrigation-induced salinity.................................................................................. 474 
7.7 References ......................................................................................................... 478 
Appendices 495 
........................................................................................................................... 496 
Assessment products ...................................................................................................... 496 
........................................................................................................................... 499 
Shortened forms ............................................................................................................. 499 
Units ........................................................................................................................... 502 
........................................................................................................................... 503 
List of figures ................................................................................................................... 503 
List of tables .................................................................................................................... 512 
Part I Introduction and 
overview 

Chapter 1 provides background and context for the Southern Gulf Water Resource Assessment 
(referred to as the Assessment). 

This chapter provides the context for and critical foundational information about the Assessment, 
with key concepts introduced and explained. 

 


Groundwater fed O’Shannassy River near the 
Australian Fossil Mammal Sites at Riversleigh. 

Photo: CSIRO – Nathan Dyer 



1 Preamble 

Authors: Seonaid Philip, Ian Watson, Cuan Petheram, Caroline Bruce 

1.1 Context 

Sustainable development and regional economic prosperity are priorities for the Australian, 
Northern Territory (NT) and Queensland governments and a number of strategies have been 
prepared to progress this. For example, the Queensland Water Strategy looks to enable regional 
economic prosperity through a vision that ‘Sustainable and secure water resources are central to 
Queensland’s economic transformation and the legacy we pass on to future generations.’ 
(Queensland Government, 2023). Acknowledging the need for continued research, the NT 
Government (2023) announced a Territory Water Plan priority action to accelerate the existing 
water science program ‘to support best practice water resource management and sustainable 
development.’ 

For remote areas like the catchments of the Southern Gulf rivers, that is Settlement Creek, 
Gregory—Nicholson River and Leichhardt River, the Morning Inlet catchments and the Wellesley 
Island groupsFigure 1-1) the land, water and other 
environmental resources or assets will be key in determining how sustainable regional 
development might occur. Primary questions in any consideration of sustainable regional 
development relate to the nature and the scale of opportunities (e.g. how water might be sourced 
to grow crops and how much water could be extracted) and their risks. 
1 (hereafter ‘Southern Gulf catchments’) (

1 Only those islands greater than 1000 ha are mapped 

The Assessment recognises that sustainable development is not a finite concept; it depends on the 
different interests and perceptions brought by individuals and communities. How people perceive 
risks is critical, especially in the context of areas such as the Southern Gulf catchments, where 
about 27% of the population is Indigenous, and more than 60% for those parts of the catchments 
away from the population centre of Mount Isa (compared with 3.2% for Australia as a whole), and 
where many Indigenous Peoples still live on the same lands they have inhabited for tens of 
thousands of years. 

Irrespective of their perspective on development, most people would agree that having access to 
reliable information about land and water resources enables informed discussion and good 
decision making. Such information includes the amount and type of a resource or asset, where it 
occurs in relation to complementary resources; what commercial uses it might have, how the 
resource changes within a year and across years; the underlying socio-economic context; and the 
potential impacts of development on people, land and water. 

Most of northern Australia’s land and water resources have not been mapped sufficiently to 
reliably inform resource allocation, mitigate investment or environmental risks, or build policy 


settings that can support good decision making. The Southern Gulf Water Resource Assessment 
findings aim to partly address this gap, to enable better decision making on private investment 
and government expenditure, taking into account intersections between existing and potential 
resource users, and enabling net development benefits to be maximised. 

The Assessment differs somewhat from many resource assessments in that it considers a wide 
range of resources or assets, rather than being a single mapping exercise of, say, soils. It also 
provides a lot of contextual information about the socio-economic profile of the catchments and 
the economic possibilities and environmental impacts of development. Further, it considers many 
of the different resource and asset types in an integrated way, rather than separately. 

 

Figure 1-1 Map of Australia showing Assessment area (Southern Gulf catchments) and other recent or ongoing 
CSIRO Assessments 

The Murray–Darling Basin and major irrigation areas and major dams (>500 GL capacity) in Australia are shown for 
context. 

The Assessment does not take an advocacy position on development, or on particular 
opportunities or risks. Rather, the Assessment provides resource information in a way that can 
inform future decision making and policy development. The outcome of no change in land use or 
water resource development is also valid. 

CSIRO has been leading similar assessments since 2012 (Figure 1-1). At that time, the Australian 
Government commissioned CSIRO to undertake the Flinders and Gilbert Agricultural Resource 
Assessment in northern Queensland as part of the North Queensland Irrigated Agriculture 
Strategy, a joint Australian Government and Queensland Government initiative. This assessment 
had a strong agricultural focus and developed fundamental soil and water datasets, providing a 
comprehensive and integrated evaluation of the feasibility, economic viability and sustainability of 
agricultural development in two catchments in northern Queensland (Petheram et al., 2013a, 

Australia and WRAs overview map 
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\1_All\1_GIS\1_Map_docs\Re-A-503_Map_Australia_and_river_basins_SG_Vic_Preamble_V1_ArcGIS10_8.mxd 
For more information on this figure please contact CSIRO on enquiries@csiro.au

2013b). Through this work and in response to two Australian Government white papers from 2015 
(the White Paper on Developing Northern Australia (PMC, 2015) and the Agricultural 
Competitiveness White Paper (Commonwealth of Australia, 2015)) the Australian Government 
commissioned CSIRO in 2016 to undertake additional, more water-focused assessments, in the 
Fitzroy catchment in WA (Petheram et al., 2018a) four catchments around Darwin in the NT 
(Petheram et al., 2018b) and the Mitchell catchment in Queensland (Petheram et al., 2018c). 
Collectively these three assessments are known as the Northern Australia Water Resource 
Assessment (NAWRA). More recently, an assessment was released for the catchment of the Roper 
River in the NT (Watson et al., 2023) and simultaneous assessments have been undertaken for the 
catchment of the Victoria River in the NT (Petheram et al., 2024) and for the Southern Gulf 
catchments of the NT and Queensland, which is summarised in this catchment report. These last 
three assessments have also been commissioned by the Australian Government through the 
National Water Grid’s Science Program, which sits within the Department of Climate Change, 
Energy, the Environment and Water. 

While land, water and other environmental resources and/or assets can be put to a variety of uses 
(including the option of ‘no change in use’), this assessment was primarily concerned with how the 
land and water might be used for irrigated agriculture, since that is the most likely pathway to 
intensified use of these resources in the coming years. 

1.2 The Southern Gulf Water Resource Assessment 

The Southern Gulf Water Resource Assessment has synthesised and summarised information from 
existing water, soil and other environmental resources in order to support regional and Country 
planning, resource management and sustainable regional development. 

The Southern Gulf catchments were identified by the Australian Government as being a suitable 
candidate for a large-scale assessment of the water and soil resources. This was due to both 
interest in, and concerns about, the development of irrigated agriculture in the catchment, and 
interest in diversifying the economy of the region. With Mount Isa, a major mining, industrial and 
service centre, situated in the headwaters of the Leichhardt River, the area is seen as having the 
potential for overcoming some of the challenges that typify northern Australia. For example, the 
Queensland Government released an economic diversification strategy for North West 
Queensland (Department of State Development, Manufacturing, Infrastructure and Planning, 
2019), which includes mining and mineral processing; beef cattle production, cropping and 
commercial fishing; tourism with an outback focus; and small business, supply chains and 
emerging industry sectors. In its 2024–25 Budget the Australian Government announced large 
investment in renewable hydrogen, low-carbon liquid fuels, critical minerals processing and clean 
energy processing (Anon, 2024). This includes investing in regions such as the North West Minerals 
Province, situated mostly within the Southern Gulf catchments. 

The Assessment aimed to: 

• improve baseline datasets of water, soil and other environmental resources and/or assets 
• understand the nature and scale of potential water resource development options 
• assess the potential environmental, social and economic impacts and risks of water resource and 
irrigation development. 



Indigenous engagement, and understanding Indigenous views about and interests in development, 
were also high priorities for the Assessment. 

It is important to note that, although these three aims are listed sequentially above, activities in 
one part of the Assessment often informed (and hence influenced) activities in an another part. 
For example, understanding ecosystem water requirements (described in Part IV of this report) 
was particularly important in establishing rules around water extraction and diversion (i.e. how 
much water can be taken and when it should be taken; described in Part III of this report). Thus, 
the procedure of assessing a study area inevitably involved iterative steps, rather than a simple 
linear process. The techniques and approaches used in the Assessment were specifically tailored 
to the study area. 

In covering the aims listed above, the Assessment was designed to: 

•explicitly address the needs of and aspirations for local development by providing objectiveassessment of resource availability, with consideration of environmental and cultural issues
•meet the information needs of governments as they assess sustainable and equitablemanagement of public resources, with due consideration of environmental and cultural issues
•address the due diligence requirements of private investors, by exploring questions ofprofitability and income reliability of agricultural and other developments.






The Assessment built on previous studies, synthesised some new data and employed an 
experienced science team, with quality assured through peer-review processes. 
The Assessment consulted with Traditional Owner representative agencies and reviewed literature 
relating to the Southern Gulf catchments and from previous Assessments within catchments of the 
Gulf of Carpentaria. Under the guidance of the Carpentaria Land Council Aboriginal Corporation, 
the team remodelled its method of consultation to engage each Prescribed Body Corporate with 
information about the Assessment and to address questions about their preferred approach for 
consultation and potential future collaboration on local issues. 
The Southern Gulf Water Resource Assessment, which incurred delays in 2021 due to the 
COVID-19 pandemic, took just over 3 years to complete, between 1 July 2021 and 30 September 
2024. 

1.2.1 Scope of work 

The Assessment comprised activities that together were designed to explore the scale of the 
opportunity for water resource development in the Southern Gulf catchments. A set of technical 
reports was produced as part of the Assessment (listed in Appendix A) from which the material in 
this catchment report was largely drawn. 

Functionally, the Assessment adopted an activities-based approach to the work (which is reflected 
in the content and structure of the outputs and products, as per Section 1.2.3) with the following 
activity groups: land suitability; surface water hydrology and climate; groundwater hydrology; 
agriculture and socio-economics; surface water storage; Indigenous water values, rights, interests 
and development goals; and ecology. 

In stating what the Assessment did, it is equally instructive to state what it did not do. 


The Assessment did not seek to advocate irrigation development or assess or enable any particular 
development; rather, it identified the resources that could be deployed in support of potential 
irrigation enterprises, evaluated the feasibility of development (at a catchment scale) and 
considered the scale of the opportunities that might exist. 

In doing so, the Assessment examined the monetary and non-monetary values associated with 
existing use of those resources, to enable a wide range of stakeholders to assess for themselves 
the costs and benefits of given courses of action. The Assessment is fundamentally a resource 
evaluation, the results of which can be used to inform planning decisions by citizens, investors, a 
range of organisations and the various tiers of government: local council, and the NT and/or 
Queensland governments and the Australian Government. The Assessment does not replace, or 
seek to replace, any planning processes; it does not recommend changes to existing plans or 
planning processes. 

The Assessment sought to lower the barriers to investment in the Assessment area by addressing 
many of the questions that potential investors would have about production systems and 
methods, crop yield expectations and benchmarks, and potential profitability and reliability. This 
information base was established for the Assessment area as a whole, not for individual paddocks, 
projects or businesses. 

The Assessment identified those areas that are most suited for new agricultural or aquaculture 
developments and industries, and, by inference, those that are not well suited. It did not assume 
that particular sections of the study area were in or out of scope. For example, the Assessment 
was blind to issues such as land-clearing regulations that may exclude land from development 
now, but might change in the future. 

The Assessment identified the types and scales of water storage and access arrangements that 
might be possible, and the likely consequences (both costs and benefits) of pursuing these 
possibilities. It did not assume that particular types or scales of water storage or water access 
were preferable to others, nor did it recommend preferred development possibilities. 

The Assessment examined resource use unconstrained by legislation or regulations, to allow the 
results to be applied to the widest range of uses, for the longest time frame possible. In doing so, 
it did not assume a particular future regulatory environment, but did consider a range of existing 
legislation, regulation and policy, and the impact of these on development. 

It was not the intention – and nor was it possible – for the Assessment to address all aspects of 
water, irrigation and agriculture development in northern Australia. Important aspects not 
addressed by the Assessment include the impacts of irrigation development on terrestrial ecology. 

1.2.2 Plausibility of development pathways 

To understand how the hydrology, ecology and economic factors in the Southern Gulf catchments 
interact with and respond to various types and scales of development, a wide range of potential 
development scenarios were examined. These ranged from small incremental increases in surface 
and groundwater extraction to water volumes defined only by the physical limits of the 
catchment. These scenarios disregarded regulatory considerations (related to, for example, water, 
land tenure or land clearing) that may exclude land from development now but might change over 
time to permit new prospects in the future. The likelihood of various scenarios will be strongly 


influenced by the regulatory framework at any point in time and by community acceptance of 
irrigated agriculture, and its benefits and risks. 

One way of understanding the nature and likely scale and rate of change in irrigated agricultural 
development, and to have meaningful discussions about future prospects in the Southern Gulf 
catchments, is to examine the scale and historical rate of change in irrigated agriculture across 
northern Australia. 

Preliminary data from a recent analysis by the Assessment team show that in 2023 there were 
about 62,000 ha of irrigated agriculture across the 310 million ha of northern Australia, as defined 
below. This is equivalent to about 0.02% of the land area. 

There are many definitions of northern Australia. The one used for these area estimations is 
defined as that part of northern Australia west of the Great Dividing Range and north of the Tropic 
of Capricorn (Figure 1-1) but including all of the NT, and all of the Gascoyne catchment, which 
includes the Carnarvon Irrigation District. The definition includes the intensively developed Ord 
River Irrigation Area (ORIA) in WA. However, the intensively developed catchments east of the 
Great Dividing Range that flow into the Great Barrier Reef lagoon (such as the Burdekin 
catchment) were not included because their biophysical and socio-economic settings are very 
different (Petheram and Bristow, 2008). For example, this eastern area contains cities such as 
Townsville and Cairns, and large irrigation areas such as the Burdekin Delta and Burdekin 
Haughton Water Supply Scheme. By comparison with the 62,000 ha of irrigated agriculture noted 
above, there are more than 350,000 ha of land developed for irrigation in these eastward-flowing 
catchments and about 2.4 million ha of land that has been developed for irrigated agriculture in 
the Murray–Darling Basin. 

There was a net increase of approximately 1300 ha per year of irrigated land across northern 
Australia (as defined above) during the 24 years between 1999 and 2023. About 26% of this 
increase was in the ORIA (WA), and about 18% in the Daly River catchment (NT), with the 
remainder of the increase across 18 other catchments. 

There are few reasons to suggest that the average rate of increase in irrigated land over the next 
few years will be very different to that seen between 1999 and 2023, notwithstanding that the NT 
Land Corporation announced a preferred developer in early 2022 of 67,500 ha of land in the NT 
(considered as Ord Stage 3), which is likely to be a mix of irrigated and mostly rainfed cropping 
land, but is dependent on existing water capture and storage as part of the ORIA. 

There are also signs that the northern jurisdictions are taking a more conservative approach to 
release of water than they have in the past. For example, the NT Government’s (2024) policy for 
taking surface water in the wet season allows for a default maximum take of 5% ‘of the 25th 
percentile of total flows for the three highest flow months of the year based on the previous 
50 years flow or modelled rainfall data of the river basin.’ This is a reduction from its previous 
policy of 20% of river flows at any time in any part of a river. Similarly, the Western Australian 
Government has taken a conservative approach to water planning in the Fitzroy catchment in the 
Kimberley, and the Queensland Water Strategy (Queensland Government, 2023) now has a 
priority to ‘Increase First Nations’ access to and ownership of water, and greater inclusion of 
cultural values and traditional knowledge in water decisions.’ 


Figure 1-2 shows the number of large dams (defined here as having a storage capacity of 10 GL or 
greater and are listed in the Australian National Committee on Large Dams database) constructed 
across Australia and northern Australia (west and east of the Great Dividing Range) over time. 
Over the past 40 years only nine large dams have been constructed across all of northern Australia 
(including the east coast), and only three of these nine dams were constructed for supplying water 
for irrigation, rather than for supplying water for mining or urban use. One of the three dams was 
also listed as having the purposes of flood mitigation, recreation and water supply for urban use. 
All three of the dams constructed to supply water for irrigation are east of the Great Dividing 
Range. No large dam has been constructed anywhere in northern Australia for the supply of water 
for irrigation for more than 25 years. 

 

Figure 1-2 Number of large dams constructed in Australia and northern Australia over time 

Large dams are defined as dams with a storage capacity of 10 GL or greater and are listed in the Australian National 
Committee on Large Dams database. 

Irrespective of the physical resources that may support water and irrigated agricultural 
development in the Southern Gulf catchments, if the future trajectory of irrigation development is 
similar to historical trends, the scale of future irrigation development in the Southern Gulf 
catchments is likely to be modest and unlikely to encompass large dam development. 

1.2.3 Assessment products 

The Assessment produced written and internet-based products. These are summarised below, and 
the written products are listed in full in Appendix A. Downloadable reports and other outputs can 
be found at: 

https://www.csiro.au/southerngulf 

Written products 

The Assessment produced the following documents: 

• technical reports, which present scientific work in sufficient detail for technical and scientific 
experts to independently verify the work 
• a catchment report, which combines key material from the technical reports, providing well-
informed but non-scientific readers with the information required for informed judgments about 


For more information on this figure please contact CSIRO on enquiries@csiro.au
06012018024018301850187018901910193019501970199020102030Number of damsYear completedNorthern AustraliaAustralia



the general opportunities and risks for, and costs and benefits associated with, water resource 
development, including irrigated agriculture or aquaculture 
•a summary report, which is provided for a general public audience
•a factsheet, which provides a summary of the key findings for the Southern Gulf catchments fora general public audience.


Audiovisual product 

The following audiovisual product was produced by the Assessment: 

•a video, providing an overview of the work.


Internet-based platforms 

The following internet-based platforms were used to deliver information generated by the 
Assessment: 

•CSIRO Data Access Portal – a portal that enables the user to download key research datasetsgenerated by the Assessment
•NAWRA Explorer – a web-based tool that enables the user to visualise and interrogate keyspatial datasets generated by the Assessment
•internet-based applications that enable the user to run selected models generated by theAssessment.


1.3 Report objectives and structure 

This is the catchment report for the Southern Gulf catchments. It summarises information from 
the technical reports for each activity and provides tools and information to enable stakeholders 
to see the opportunities for development and the risks associated with them. Using the 
establishment of a ‘greenfield’ (not having had any previous development for irrigation) irrigation 
development as an example, Figure 1-3 illustrates many of the complex considerations required 
for such development; key report sections that inform these considerations are also indicated. 

The structure of the Southern Gulf catchments report is as follows: 

•Part I (Chapter 1) provides background, context and a general overview of the Assessment.
•Part II (Chapter 2 and Chapter 3) looks at current resources and conditions within thecatchments.
•Part III (Chapter 4 and Chapter 5) considers the opportunities for water, agricultural andaquaculture development based on the available resources.
•Part IV (Chapter 6 and Chapter 7) provides information on the economics of development and arange of risks of development, as well as on those risks that might accompany development.





Figure 1-3 Schematic of key components and concepts in the establishment of a greenfield irrigation development 

Numbers shown in blue refer to sections of this report. 

1.3.1 Part I – Introduction 

This part of the report provides a general overview of the Assessment. Chapter 1 (this chapter) 
covers the background and context of the Assessment. Key findings can be found in the front 
materials of this report. 

1.3.2 Part II – Resource information for assessing potential development 
opportunities 

Chapter 2 is concerned with the physical environment, seeking to describe the soil and water 
resources present in the Southern Gulf catchments, including: 

•geology and physical geography: focusing on those aspects that are important for understandingthe distribution of soils, groundwater flow systems, suitable water storage locations and geologyof economic significance
•soils: covering the soil types within the catchment, the distribution of key soil attributes andtheir general suitability for irrigated agriculture




•climate: outlining the general climatic circulatory systems affecting the catchment and providinginformation on key climate parameters of relevance to irrigation under current and futureclimates
•hydrology: describing and quantifying the surface water and groundwater hydrology of thecatchment.


Chapter 3 is concerned with the living and built environment, providing information about the 
people and the ecology of the Southern Gulf catchments and the institutional context of the 
catchments, describing: 

•ecology: ecological systems and assets of the Southern Gulf catchments, including the keyhabitats, key biota and their important interactions and connections
•socio-economic profile: current demographics, and existing industries and infrastructure ofrelevance to water resource development in the Southern Gulf catchments
•Indigenous values, rights, interests and development objectives.


1.3.3 Part III – Opportunities for water resource development 

Chapter 4 presents information about the opportunities for irrigated agriculture and aquaculture 
in the Southern Gulf catchments, describing: 

•land suitability for a range of crop × season × irrigation type combinations, and for aquaculture,
including key soil-related management considerations
•cropping and other agricultural opportunities, including crop yields and water use
•gross margins at the farm scale
•prospects for integration of forages and crops into existing beef enterprises
•aquaculture opportunities.


Chapter 5 presents information about opportunities for extracting and/or storing water for use in 
the Southern Gulf catchments, describing: 

•groundwater and subsurface storage opportunities
•surface water storage opportunities in the Southern Gulf catchments, including major dams,
large farm-scale dams and natural water bodies
•estimates of the quantity of water that could be pumped or diverted from the Nicholson,
Gregory and Leichhardt rivers and their major tributaries
•water distribution systems (i.e. for conveyance of water from a dam and application to a crop)
•costs of potential broad-scale irrigation development.


1.3.4 Part IV – Economics of development and accompanying risks 

Chapter 6 covers economic opportunities and constraints for water resource development, 
describing: 

•balance of scheme-scale costs and benefits
•cost–benefit considerations for water infrastructure viability



•regional-scale economic impacts of irrigated development.


Chapter 7 discusses a range of risks of development, including those that might accompany 
development, describing: 

•ecological impacts of altered flow regimes on aquatic, riparian and near-shore marine ecology
•biosecurity risks to agricultural or aquaculture enterprises
•potential off-site impacts (due to sediment, nutrients and agri-pollutants) to receiving waters inthe catchments
•irrigation-induced salinity due to rising watertables.










1.3.5 Appendices 
This report contains three appendices: 
Appendix A – list of information products 
Appendix B – shortened forms and units 
Appendix C – list of figures and list of tables. 

1.4 Key background 

1.4.1 The Southern Gulf catchments 

The Southern Gulf catchments (Figure 1-4) have an area of 108,200 km2 and encompass the 
Settlement Creek (17,600 km2), Gregory–Nicholson (52,200 km2), Leichhardt (33,400 km2) and 
Morning Inlet (3700 km2) catchments and some of the islands of the Wellesley Island groups2. The 
majority of the published information from these catchments is focused on the Queensland 
portion of the area (79% of the Assessment area). Less well known, and more remote, is the 21% 
of the study area in the NT. The Assessment area has a population of approximately 22,500, the 
majority residing in the major regional service centre Mount Isa (18,000) and smaller centres at 
Doomadgee (1400), Gununa (1025) and Burketown (200) (ABS, 2021). The nearest major city and 
population centre is Townsville (192,768 in the 2021 Census), approximately 900 km by road from 
Mount Isa. The climate of the Southern Gulf catchments is hot and semi-arid to dry subhumid. The 
majority of streams and rivers are ephemeral, with a notable exception being the Gregory River 
and its tributaries Lawn Hill Creek and O’Shannassy River, into which groundwater discharges from 
karstic carbonate rocks in their headwaters. As a proportion of its median annual streamflow, the 
water in the Leichhardt River is more heavily regulated than most other rivers in northern 
Australia west of the Great Dividing Range. Several large reservoirs in the catchment of the 
Leichhardt River, namely Lake Julius (108 GL capacity) and Lake Moondarra (107 GL capacity) are 
used conjunctively to supply water for urban, mining and industrial use around Mount Isa and 
Cloncurry. Lake Moondarra is also used by Mount Isa residents and others for recreation. A low 
weir (of less than 1 GL capacity) upstream of the road crossing impounds water on the Nicholson 
River downstream of Doomadgee. 

2 Only those islands greater than 1000 ha are mapped. 




Figure 1-4 The Southern Gulf catchments 

ALRA = Aboriginal Land Rights (Northern Territory) Act 1976. IPA = Indigenous Protected Area; NP = national park; NR 
= nature refuge. 



Southern Gulf catchments overview map
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For more information on this figure please contact CSIRO on enquiries@csiro.au

The main land uses in the Assessment area are grazing native vegetation (77% of the Assessment 
area), and conservation and natural environments (16%). Cropping (both rainfed and irrigated) are 
sparsely practised (<0.04%). Mining, while a significant economic activity in the Assessment area, 
uses less than 1% of the land area. Protected areas located in the Southern Gulf catchments 
include the United Nations Educational, Scientific and Cultural Organization World Heritage–listed 
Australian Fossil Mammal Sites (Riversleigh); three Indigenous Protected Areas, namely 
Ganalanga–Mindibirrina, Nijinda Durlga and Thuwathu/Bujimulla; and Boodjamulla (Lawn Hill) and 
Finucane Island national parks and other conservation parks. In addition to these protected areas, 
the Southern Gulf catchments contain 13 nationally significant wetlands listed in the Directory of 
Important Wetlands in Australia. 

1.4.2 Wet–dry seasonal cycle: the water year 

Northern Australia has a highly seasonal climate, with most rain falling during the 4-month period 
from December to March. Unless specified otherwise, this Assessment defines the wet season as 
being the 6-month period from 1 November to 30 April, and the dry season as the 6-month period 
from 1 May to 31 October. However, it should be noted that the transition from the dry to the wet 
season typically occurs in October or November, and the definition of the northern wet season 
commonly used by meteorologists is 1 October to 30 April. 

All results in the Assessment are reported over the water year, defined as the period 1 September 
to 31 August, unless specified otherwise. This allows each individual wet season to be counted in a 
single 12-month period, rather than being split over two calendar years (i.e. counted as two 
separate seasons). This is more realistic for reporting climate statistics from hydrological and 
agricultural assessment viewpoints. 

1.4.3 Scenario definitions 

The Assessment considered four scenarios, reflecting combinations of different levels of 
development, and historical and future climates, much like those used in the Northern Australia 
Sustainable Yields project (CSIRO, 2009a, 2009b, 2009c), the Flinders and Gilbert Agricultural 
Resource Assessment (Petheram et al., 2013a, 2013b), the Northern Australia Water Resource 
Assessments (Petheram et al., 2018a, 2018b, 2018c) and the Roper River Water Resource 
Assessment (Watson et al., 2023): 

• Scenario A – historical climate and current development 
• Scenario B – historical climate and future development 
• Scenario C – future climate and current development 
• Scenario D – future climate and future development. 


Scenario A 

Scenario A and its subsets, Scenario AN and Scenario AE, assume a historical climate. The historical 
climate series is defined as the observed climate (rainfall, temperature and potential evaporation 
for water years from 1 September 1890 to 31 August 2022). All results presented in this report 
were calculated over this period, unless otherwise specified. Historical tidal data were used to 
specify downstream boundary conditions for the flood modelling. 


Scenario A assumes current levels of surface water development and that existing water licence 
holders use their full entitlement. For more information see the companion technical report on 
river model simulation in the Southern Gulf catchments (Gibbs et al., 2024). Strategic reserves are 
not included under Scenario A. 

Scenario AN assumes no water resource development. 

Scenario AE assumes current levels of surface water development, estimates actual use of the 
existing entitlement holders and applies this over the entire historical period. Strategic reserves 
are not included. 

The results under scenarios AN and AE only differ from the results under Scenario A in the 
Leichhardt catchment, because other catchments in the study area have no or very small 
(≤5 GL/year) entitlement volumes. 

Scenario B 

Scenario B is historical climate and future hypothetical development assessed at approximately 
2060. Scenario B uses the same historical climate series as Scenario A. River inflow was modified 
to reflect potential future development. Potential development options are entirely hypothetical 
and were devised to assess the response of hydrological, ecological and economic systems to 
future development ranging from small incremental increases in surface water through to 
extraction volumes representative of the likely physical limits of the Southern Gulf catchments (i.e. 
considering the co-location of suitable soil and water). Price and cost information was indexed to 
December 2023 unless otherwise specified. The impacts of future hypothetical developments on 
existing licence holders in the Leichhardt catchment are reported. 

The impacts of changes in flow due to this future development were assessed, including impacts 
on: 

•instream, riparian and near-shore ecosystems
•Indigenous water values
•economic costs and benefits
•opportunity costs of expanding irrigation
•institutional, economic and social considerations that may impede or enable adoption ofirrigated agriculture.


Scenario C 

Scenario C is future climate and current levels of surface water assessed at approximately 2060. 
Future climate impacts on water resources were explored within a sensitivity analysis framework 
by applying percentage changes in rainfall and potential evaporation to modify the 132-year 
historical climate series (as in Scenario A). The percentage change values adopted were informed 
by projected changes in rainfall and potential evaporation under Shared Socio-economic Pathways 
(SSP) 2-4.5 and 5-8.5 as defined in the IPCC Sixth Assessment Report 
on Climate change 
(IPCC, 
2022). SSP 2-4.5 is broadly considered representative of a likely projection given current global 
commitments to reducing emissions, and SSP 5-8.5 is representative of an (unlikely) upper bound. 


Scenario D 

Scenario D is future climate and future hypothetical development. It uses the same future climate 
series as Scenario C. River inflow was modified to reflect future hypothetical developments, as in 
Scenario B. Therefore, in this report, the climate data for scenarios A and B are the same 
(historical observations from 1 September 1890 to 31 August 2022), and the climate data for 
scenarios C and D are the same (the above historical data scaled to reflect a plausible range of 
future climates). 

1.5 References 

Australian Bureau of Statistics (ABS) (2021) Census of population and housing time series profile. 
Catalogue number 2003.0 for various SA regions falling partly within the Southern Gulf 
catchments. Australian Bureau of Statistics, Canberra. Viewed 29 October 2023, 
https://www.abs.gov.au/census/find-census-data/search-by-area. 

Anon (2024) Budget 2024-25. A future made in Australia. Viewed 11 September 2024, 
https://budget.gov.au/content/factsheets/download/factsheet-fmia.pdf. 

Commonwealth of Australia (2015) Agricultural Competitiveness White Paper, Canberra. Viewed 
24 September 2024, https://www.agriculture.gov.au/sites/default/files/documents/ag-
competitiveness-white-paper_0.pdf 

CSIRO (2009a) Water in the Gulf of Carpentaria Drainage Division. A report to the Australian 
Government from the CSIRO Northern Australia Sustainable Yields Project. CSIRO Water for 
a Healthy Country Flagship, Australia. https://doi.org/10.4225/08/5859749d4c71e. 

CSIRO (2009b) Water in the Timor Sea Drainage Division. A report to the Australian Government 
from the CSIRO Northern Australia Sustainable Yields Project. CSIRO Water for a Healthy 
Country Flagship, Australia. https://doi.org/10.4225/08/585ac5bf09d7c. 

CSIRO (2009c) Water in the Northern North-East Coast Drainage Division. A report to the 
Australian Government from the CSIRO Northern Australia Sustainable Yields Project. CSIRO 
Water for a Healthy Country Flagship, Australia. 
https://doi.org/10.4225/08/585972c545457. 

Department of State Development, Manufacturing, Infrastructure and Planning (2019) North west 
Queensland economic diversification strategy 2019. Viewed 12 September 2024, 
https://www.statedevelopment.qld.gov.au/regions/regional-priorities/a-strong-and-
prosperous-north-west-queensland/north-west-queensland-economic-diversification-
strategy. 

Gibbs M, Hughes J, Yang A, Wang B, Marvanek S and Petheram C (2024) River model scenario 
analysis for the Southern Gulf catchments. A technical report from the CSIRO Southern Gulf 
Water Resource Assessment for the National Water Grid. CSIRO, Australia. 

Intergovernmental Panel on Climate Change (IPCC) (2022) Climate Change 2022: Impacts, 
adaptation, and vulnerability. Contribution of Working Group II to the Sixth Assessment 
Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, 
Cambridge, UK and New York, NY. 

NT Government (2023) Territory Water Plan. A plan to deliver water security for all Territorians, 
now and into the future. Viewed 6 September 2024, 


https://watersecurity.nt.gov.au/__data/assets/pdf_file/0003/1247520/territory-water-
plan.pdf. 

NT Government (2024) Surface water take – wet season flow policy. Viewed 25 July 2024, 
https://nt.gov.au/__data/assets/pdf_file/0008/1348190/surface-water-take-wet-season-
flow-policy.pdf. 

Petheram C and Bristow K (2008) Towards an understanding of the hydrological factors, 
constraints and opportunities for irrigation in northern Australia: a review. Science Report 
No. 13/08. CRC for Irrigation Futures Technical Report No. 06/08. CSIRO Land and Water, 
Australia. 

Petheram C, Watson I and Stone P (eds) (2013a) Agricultural resource assessment for the Flinders 
catchment. A report to the Australian Government from the CSIRO Flinders and Gilbert 
Agricultural Resource Assessment, part of the North Queensland Irrigated Agriculture 
Strategy. CSIRO Water for Healthy Country and Sustainable Agriculture flagships, Australia. 

Petheram C, Watson I and Stone P (eds) (2013b) Agricultural resource assessment for the Gilbert 
catchment. A report to the Australian Government from the CSIRO Flinders and Gilbert 
Agricultural Resource Assessment, part of the North Queensland Irrigated Agriculture 
Strategy. CSIRO Water for Healthy Country and Sustainable Agriculture flagships, Australia. 

Petheram C, Bruce C, Chilcott C and Watson I (eds) (2018a) Water resource assessment for the 
Fitzroy catchment. A report to the Australian Government from the CSIRO Northern 
Australia Water Resource Assessment, part of the National Water Infrastructure 
Development Fund: Water Resource Assessments. CSIRO, Australia. 

Petheram C, Chilcott C, Watson I, Bruce CI (eds) (2018b) Water resource assessment for the 
Darwin catchments. A report to the Australian Government from the CSIRO Northern 
Australia Water Resource Assessment, part of the National Water Infrastructure 
Development Fund: Water Resource Assessments. CSIRO, Australia. 

Petheram C, Philip S, Watson I, Bruce C and Chilcott C (eds) (2024) Water resource assessment for 
the Victoria catchment. A report from the CSIRO Victoria River Water Resource Assessment 
for the National Water Grid. CSIRO, Australia. 

Petheram C, Watson I, Bruce C and Chilcott C (eds) (2018c) Water resource assessment for the 
Mitchell catchment. A report to the Australian Government from the CSIRO Northern 
Australia Water Resource Assessment, part of the National Water Infrastructure 
Development Fund: Water Resource Assessments. CSIRO, Australia. 

Prime Minister and Cabinet (PMC) (2015) Our North, Our Future: White Paper on Developing 
Northern Australia, Prime Minister and Cabinet, Commonwealth Government of Australia, 
2015. Viewed 24 September, 
https://www.infrastructure.gov.au/sites/default/files/documents/nawp-fullreport.pdf 

Queensland Government (2023) Queensland Water Strategy. Water. Our life resource. Viewed 11 
September 2024, https://www.rdmw.qld.gov.au/qld-water-strategy/strategic-direction. 

Watson I, Petheram C, Bruce C and Chilcott C (eds) (2023) Water resource assessment for the 
Roper catchment. A report from the CSIRO Roper River Water Resource Assessment for the 
National Water Grid. CSIRO, Australia. 


Part II Resource information 
for assessing potential 
development 
opportunities 

Chapters 2 and 3 provide baseline information that readers can use to understand what soils and 
water resources are present in the Southern Gulf catchments and the current living and built 
environment of the Southern Gulf catchments. This information covers: 

•the physical environment (Chapter 2)
•the people, ecology and institutional context (Chapter 3).





The Leichhardt River downstream of its 
junction with Gunpowder Creek. Loamy 
and clayey-surfaced friable soils are 
adjacent to the river. Treeless alluvial clay 
plains can be seen in the distance. 

Photo: CSIRO – Nathan Dyer 



2 Physical environment of the Southern Gulf 
catchments 

Authors: Matthias Raiber, Matt Gibbs, Peter Zund, Andrew R Taylor, Seonaid Philip, Steve Marvanek, 
David McJannet, Fazlul Karim, Bill Wang, Cuan Petheram, Russell Crosbie, Justin Hughes 

Chapter 2 examines the physical environment of the catchments of the Southern Gulf rivers – that is, 
Settlement Creek, Gregory–Nicholson River and Leichhardt River, the Morning Inlet catchments and 
the Wellesley island groupsFigure 2-1. 
1 – and seeks to identify the available soil and water resources. It provides 
fundamental information about the geology, soil, climate, and the river and groundwater systems of 
the catchment. These resources underpin the natural environment and existing industries, providing 
physical bounds to the potential scale of irrigation development. Key components and concepts are 
shown in 

1 Only those islands greater than 1000 ha are mapped. 



Figure 2-1 Schematic diagram of key natural components and concepts in the establishment of a greenfield irrigation 
development 

"\\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\10_Reporting\1_All\9_Graphics_artist\3_Vic and SoG\C Bruce Vic CR Chp2_8_2024.jpg"
Numbers in blue refer to sections in this report. 


2.1 Summary 

This chapter provides a resource assessment of the geology, soil, climate, groundwater and surface 
water resources of the Southern Gulf catchments. No attempt is made in this chapter to calculate 
physically plausible areas of land or volumes of water that could potentially be used for agriculture or 
aquaculture developments. Those analyses are reported in chapters 4 and 5. 

2.1.1 Key findings 

Soils 

The soils with potential for agriculture in the Southern Gulf catchments are dominated by cracking 
clay soils (23% of the catchment), which are principally found on floodplains and alluvial plains of the 
Armraynald Plain and Barkly Tableland physiographic units. They typically have a moderate to high 
agricultural potential, are deep with a high soil available water capacity (AWC) and are suited to a 
wide variety of irrigated dry-season crops. Flooding, access and trafficability in the wet season are 
common constraints across the lower parts of the Armraynald Plain, and crop tolerance to poor soil 
drainage conditions restricts wet-season cropping in these areas. High salt levels within the soil 
profile in areas of the Armraynald Plain need management consideration. Friable, non-cracking clay 
soils (3% of the catchments) and loamy soils (~3% of the catchments) make up substantial areas. Both 
of these soils are well drained, and the friable, non-cracking clay soils have a generally high 
agricultural potential while the loamy soils have moderate to high agricultural potential. Sandy soils 
(10% of the catchment) have moderate agricultural potential with spray or trickle irrigation, although 
low to moderate water-holding capacity and hardsetting surface soils are common constraints. 
Shallow and/or rocky soils make up just over 56% of the catchment and have been assessed as having 
limited to no potential for agricultural development. These areas do, however, have substantial 
habitat value and broader biodiversity and cultural values. 

Climate 

The Southern Gulf catchments have a hot and arid climate that is highly seasonal with an extended 
dry season. They receive a mean rainfall of 602 mm/year, 94% of which falls during the wet season. 
Mean daily temperatures and potential evaporation are high relative to other parts of Australia. On 
average, potential evaporation is approximately 1900 mm/year. 

Overall, the climate of the Southern Gulf catchments generally suits a wide range of crops, though in 
most years rainfall would need to be supplemented with irrigation. The variation in rainfall from one 
year to the next is moderately high compared to elsewhere in northern Australia and high compared 
to other parts of the world with similar mean annual rainfall. The Southern Gulf catchments do not 
experience unusually long sequences of dry years, and the magnitude of dry spells is similar to many 
areas in the Murray–Darling Basin and the east coast of Australia. Since the 1969–70 water year 
(1 September to 31 August), the Southern Gulf catchments have experienced one tropical cyclone in 
36% of cyclone seasons and two tropical cyclones in 4% of seasons. 

Approximately 10% of the global climate models (GCMs) project an increase in mean annual rainfall 
by more than 5%, 22% project a decrease in mean annual rainfall by more than 5% and about 73% 
indicate ‘little change’. 


Surface water and groundwater 

The timing and event-driven nature of rainfall events and high potential evaporation rates across the 
Southern Gulf catchments have important consequences for the catchments’ hydrology. 
Approximately 97% of runoff occurs during the wet season (November to April, inclusive), and 87% of 
all runoff occurs during the 3-month period from January to March, which is very different to 
southern Australia where rainfall and runoff are less seasonal. This means that, in the absence of 
groundwater, water storages are essential for dry-season irrigation. 

The major aquifers in the Southern Gulf catchments occur within dissolution features in the 
dolostones and limestones of the Cambrian (541 to 485 million years ago (Ma)) Georgina Basin in the 
west of the Southern Gulf catchments, the Late Jurassic to Early Cretaceous Gilbert River Formation 
and, to a lesser extent, the Normanton Formation within the Carpentaria Sub-basin of the Great 
Artesian Basin (GAB). 

The carbonate rocks of the Georgina Basin, in particular the Camooweal Dolostone and Thorntonia 
Limestone, form part of a complex, interconnected and highly productive regional-scale groundwater 
system (about 460,000 km2) that extends for hundreds of thousands of square kilometres west, south 
and north of the south-western boundaries of the Southern Gulf catchments. Mean annual 
volumetric recharge over the aquifers of the Georgina Basin within the Southern Gulf catchments is 
estimated to be 122 GL/year. Bore yields are variable due to the complex nature of the karstic 
aquifer, but often range from less than 1 to 20 L/second. The carbonate rocks of the Georgina Basin 
are a complex regional-scale groundwater system due to the variability and interconnectivity 
between fractures, fissures and karsts. Currently about 1.8 GL/year of groundwater is licensed to be 
extracted from the Camooweal Dolostone and Thorntonia Limestone within the Southern Gulf 
catchments (see Section 3.3.4). 

The Gilbert River Formation and Normanton Formation host the most regionally extensive aquifer 
systems within the Southern Gulf catchments, where they extend over the eastern part of the 
catchment in Queensland and are entirely covered by the Cenozoic (66 Ma to present) Karumba 
Basin. Bore yields of the Gilbert River Formation are variable, ranging from less than 1 to 
46 L/second. The aquifers of the geological Carpentaria Basin form part of the 1.7 million km2 large 
GAB, which reaches far to the south and east of the Southern Gulf catchments and includes the 
Eromanga and Surat basins and parts of the Clarence–Moreton Basin. 

Other local- to intermediate-scale aquifer systems are likely to exist in other geological formations 
within the Southern Gulf catchments. For example, the Cenozoic alluvium may offer potential in 
terms of water quality (median total dissolved solids (TDS) of approximately 600 mg/L). However, 
only limited data are available to assess lithological variability, hydraulic properties and the spatial 
extent of potential productive aquifers. 

The Southern Gulf catchments consist of various rivers and streams that discharge into the southern 
Gulf of Carpentaria. The most substantial of these are the Leichhardt, Gregory and Nicholson rivers. 
The median and mean annual discharges from the Southern Gulf catchments into the Gulf of 
Carpentaria are 4961 and 6759 GL/year, respectively. The majority of this volume is relatively evenly 
split between the Leichhardt and Gregory-Nicholson River catchments. Most rivers cease to flow over 
the dry season (27% to 79% of the time), however the Gregory River is a notable exception with 
perennial flow resulting from discharge from the Thorntonia Limestone hydrogeological unit. Current 
surface water licences across the study area total about 114 GL (i.e. 2.3% of the median annual 


discharge from the study area), with the majority of these licences in the Leichhardt River catchment, 
including those supplied from Lake Moondarra and Lake Julius (Section 3.34). 

Many rivers in the catchments, particularly those in the southern parts of the Southern Gulf 
catchments, are ephemeral and are reduced to a few scarce and vulnerable waterholes during the 
dry season. Some waterholes and river reaches, particularly those in the upper reaches of the 
Gregory River, are permanent and are replenished by groundwater (see Section 2.5.4). 

2.1.2 Introduction 

This chapter seeks to address the question: What soil and water resources are available for irrigated 
agriculture in the Southern Gulf catchments? 

The chapter is structured as follows: 

• Section 2.2 examines the geology of the Southern Gulf catchments, which is important in 
understanding the distribution of groundwater, soil and areas of low and high relief, which in turn 
influence flooding and the deposition of soil. 
• Section 2.3 examines the distribution and attributes of soils in the Southern Gulf catchments and 
discusses management considerations. 
• Section 2.4 examines the climate of the Southern Gulf catchments, including historical data and 
future projections of patterns in rainfall. 
• Section 2.5 examines the groundwater and surface water hydrology of the Southern Gulf 
catchments, including groundwater recharge, streamflow and flooding. 


2.2 Geology and physical geography of the Southern Gulf catchments 

2.2.1 Geological history 

The geological history of an area describes the major periods of deposition and tectonics (i.e. major 
structural changes) as well as weathering and erosion. These processes are closely linked to the 
physical environment that influences the evolution and formation of resources such as valuable 
minerals, coal, groundwater and soil. Geology also determines topography, which in turn is a key 
factor in the location of potential dam sites, flooding and deposition of soil. These resources are all 
important considerations when identifying suitable locations for large water storages and when 
understanding past and present ecological systems and patterns of human settlement. 

The oldest rocks in the Southern Gulf catchments are late Proterozoic (1780 to 1400 million years 
old). They consist of repeated thick sequences of sedimentary and metamorphic rocks and volcanics 
that include numerous prominent beds of sandstone (Figure 2-2). These sequences were deposited in 
a series of basins (e.g. the McArthur and South Nicholson basins and the Isa Superbasin) extending 
across the area and then folded, faulted and intruded (i.e. broken through) by igneous rocks to form 
mountain chains. Towards the end of the Proterozoic, the mountain chains had been eroded down to 
a level not far above that of the current topography. 


 

Surface geology map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\4_Water_storage\3_S_Gulf\1_GIS\1_Map_docs\WS510-S_Catchment_1M_Geology_overview_v02_CR.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-2 Surface geology of the Southern Gulf catchments 

Source: adapted from Raymond (2012) 

 


During the Neoproterozoic to late Palaeozoic (850 to 350 Ma), the limestones, dolomites and minor 
sandstones of the Georgina Basin were deposited on a tectonically inactive platform. The Cambrian 
strata provide an important regional groundwater source in the west and south-west of the Southern 
Gulf catchments and are largely concealed by overlying Cretaceous sediments. 

The Jurassic to Cretaceous (125 to 100 Ma) geological Carpentaria Basin, a sub-basin of the GAB, 
hosts sequences of interbedded sandstones, mudstones and siltstones. These sequences underlie 
most of the eastern part of the Southern Gulf catchments and extend and thicken offshore. They 
include deposits of the Gilbert River Formation (GRF), which is composed of fluvial quartzose 
sandstones and forms the major GAB aquifer and is an important groundwater resource within the 
Southern Gulf catchments. Following deposition of the GRF, widespread transgression and then 
major regression in the late Middle Cretaceous led to deposition of the thick mudstone successions 
of the Wallumbilla Formation and erosion and deposition of a thin succession of Cretaceous shallow 
marine sandstones, conglomerates and mudstones. 

Extensive Cenozoic alluvial plains deposits unconformably overlie the geological Carpentaria Basin 
and mostly correspond to the Cenozoic Karumba Basin, which is persistent across much of northern 
Queensland and extends into eastern parts of the NT. 

Overlying the Karumba Basin are the youngest sediments in the catchments: the alluvial sands, silts 
and gravels associated with the beds, channels and floodplains of the catchments’ rivers and creeks 
and their tributaries. 

The present landscape has been produced by warping and dissection of a series of erosion surfaces 
formed during several cycles of erosion that started in the Late Cretaceous about 70 Ma and ended in 
the mid-Cenozoic era about 25 Ma. During this time, stable crustal conditions and subaerial exposure 
led to patchy erosion of the Cretaceous rocks and prolonged subaerial weathering of the remaining 
Cretaceous and Proterozoic rocks, resulting in the formation of deep weathering profiles and 
associated iron-cemented capping. 

Between the mid-Cenozoic and the present day, there has been gentle uplift and warping of the 
various surfaces and their weathered cappings. Continued erosion has led to the emergence of the 
present-day landscape, and extensive floodplains and coastal deposits were built up on the margins 
of modern drainage systems and the coastline, respectively, in the Southern Gulf catchments. 

2.2.2 Physiography of the Southern Gulf catchments 

Ten physiographic units have been identified based on the geological controls outlined in Section 
2.2.1. They are described in the companion technical report on digital soil mapping and land 
suitability (Thomas et al., 2024) and shown in Figure 2-3. 




Physiographic map 
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\3_Land_suitability\4_S_Gulf\1_GIS\1_Map_docs\LL-S-501_location_v2_v11_Arc10_8.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-3 Physiographic units of the Southern Gulf catchments 

Physiographic units as described in the companion technical report on digital soil mapping and land suitability (Thomas et 
al., 2024) and based on Grimes (1974). Significant settlements and roads are overlaid on hillshaded terrain relief. 




The mainland Assessment areas can be split into the uplands and the Carpentaria Plains (Grimes, 
1974). The upland area in the south and west reaches 620 metres above sea level (mASL) and is the 
headwaters for Assessment area catchments. The uplands can be divided into four physiographic 
units: Isa Highland, Barkly Tableland, Dissected Barkly Tableland and Gulf Fall (Figure 2-3). 

The oldest and most elevated and rugged unit is the Isa Highland (Twidale, 1956). It consists of 
Precambrian (>545 Ma) volcanic and sedimentary rocks that have been metamorphosed, weathered 
and eroded. Soil parent materials within the Isa Highland from west to east include rhyolite, basalt, 
dolomitic sediments, siltstone, meta basalt, granite, quartzite and metasediments. Land surface relief 
is moderate (200 to 230 m) and generally in a south–north alignment. 

The next most elevated upland physiographic unit is a small part of Barkly Tableland to the west of 
the Isa Highland. The tableland started out as a sedimentary basin in Precambrian times and then 
was uplifted, folded and eroded. During the Cambrian period, seas transgressed the area and 
deposited carbonate sediments in the depressions. Later the Cambrian-period sediments were 
exposed and eroded. During the Mesozoic, isolated lakes and swamps developed (Randal, 1966), and 
subsequently, during the Cenozoic period, the upland areas experienced deep weathering and 
laterisation. However, areas covered by lakes and swamps did not undergo strong leaching, and as 
the landscape dried, the current cracking clay soils formed on relatively fresh sediments (Christian et 
al., 1954). The clay soils overlie dolomitic rocks. Relief is very low (9 to 30 m), and Mitchell grasslands 
dominate. 

Since the Cambrian period, the drainage network that flows towards the Gulf of Carpentaria has 
dissected the tableland, leaving remnant land features defined by deep narrow gorges. This area is 
mapped as the Dissected Barkly Tableland physiographic unit in Figure 2-3. Dissection has been 
amplified because the underlying rocks formed from dolomitic sediments are relatively soluble 
compared to surrounding rocks. These gorges have intersected the groundwater systems of the 
tableland, resulting in spring-fed permanent creeks and rivers such as the O’Shannassy, Gregory and 
Lawn Hill Creek subcatchments. 

The remaining parts of the uplands, comprising mainly Mesozoic sedimentary formations 
(sandstones), have been eroded into a complex pattern of easterly flowing streams and valleys 
separated by ranges and outcrops of sedimentary formations (Mullera Formation, Constance 
Sandstone and Fickling Beds; Smith and Roberts (1972)). This physiographic unit is known as the Gulf 
Fall, and the Nicholson and South Nicholson rivers are the primary systems draining this area. 
Musselbrook, Lagoon, Settlement, Gold and Running creeks also drain this area. 

To the east of the uplands are the Carpentaria Plains comprising a series of plains, pediments and 
remanent plateaux that can be divided into six physiographic units: Cloncurry Plain, Doomadgee 
Plain, Armraynald Plain, Karumba Plain, Donors Plateau and Mornington Plateau (Figure 2-3). 

The most elevated sedimentary plain (30 to 150 mASL) is the Cloncurry Plain physiographic unit 
immediately east of the uplands. It consists of gently sloping colluvial and fluvial sedimentary plains 
and pediments with isolated low hills of Precambrian rock. Streams are few and incised into the 
pediments with narrow alluvial plains (Grimes, 1974). The Cloncurry Plain unit extends from the 
middle reach of the Leichhardt River to Lawn Hill Creek. 

In the northern Assessment area, the Doomadgee Plain physiographic unit lies below and adjacent to 
the Cloncurry Plain. It is predominantly a sandy, gently undulating plain overlying a deeply weathered 


Cenozoic land surface. Low eucalypt and paperbark scrub cover the lands. Widely spaced creeks drain 
the plains, currently in a radial north-westerly direction towards the coast. This suggests that the 
underlying old land surface could have been a large sedimentary fan. Prior streams of sandier soils, 
shallow swampy and water-filled depressions (particularly between Lilly and Moonlight creeks) and 
small pits caused by ferricrete subsidence occur throughout the plains (Grimes, 1974). 

In the southern half of the Assessment area, the Armraynald Plain physiographic unit lies below and 
adjacent to the Cloncurry Plain unit. It consists of argillaceous Cenozoic (Quaternary period) 
sediments (Armraynald Beds) that form black soils covered in grasslands. Stream channels are few, 
widely spaced and deeply incised due to sea-level changes. The plains extend up the Lawn Hill Creek, 
and the Gregory and Leichhardt valleys. Lawn Hill Creek and Gregory River are spring-fed permanent 
streams. The Gregory River splits into a giant braid (20 km at its widest) of permanent streams 
consisting of the Gregory River, Beames Brook, Barkly River and Running Creek downstream of the 
Gregory Crossing. Monsoonal rainforest grows immediately adjacent to these permanent streams 
that cross the otherwise grassland plains (Grimes, 1974). 

Downslope of both the Doomadgee Plain and Armraynald Plain lies the coastal Karumba Plain 
physiographic unit. This coastal unit extends 10 to 35 km inland from the Gulf of Carpentaria coast 
and is widest near the Albert River mouth (upstream called the Nicholson and Gregory rivers). This 
plain consists of Holocene beach ridges and tidal and extratidal flats and plains. Some of the inland 
plains only flood when the rivers are in spate or when the north-westerly winds cause exceptionally 
high tides during the monsoon. Because the plain is generally flat and wide and the tidal range is 
moderate (about 3.5 m), tidal waters can rapidly inundate the land. Mangroves and tidal flats 
dominate the coastline; beaches are few and consist of white shelly sand. Small crescent dunes have 
formed in places from wind action (Grimes, 1974). Strong north-easterly winds across the bare plains, 
especially in November, may cause a fog-like effect in Burketown from suspended particles. Due to 
the flatness of the plain, streams meander in complex patterns. 

To the east of the Armraynald Plain lies the Donors Plateau physiographic unit. This slightly elevated 
unit (10 to 80 mASL) forms a watershed between the catchments of the Leichhardt and Flinders rivers 
and forms the eastern boundary of the Assessment area. The plateau consists of siliceous sediments 
laid down in the Early Cretaceous epoch from upland sediment sources of the Normanton Formation. 
The plain, which was once more extensive, was deeply weathered and lateralised in the highest 
elevation parts in the Tertiary period and has subsequently been stripped away in parts, leaving 
today’s Donors Plateau and exposed older Cretaceous sediments. In parts, the older sediments have 
been re-covered by sediments laid down during the Pleistocene, forming the Armraynald Plain 
(Ingram, 1972). 

Much of the Wellesley Islands in the Gulf of Carpentaria represent remnants of a mainland laterised 
Cretaceous period plain called the Mornington Plateau physiographic unit. This unit is 5 to 20 mASL. 
Dissection of the unit is not as extensive as in the Donors Plateau unit. The Mornington Plateau unit is 
generally fringed with marine plains consisting of coastal sediments or dune fields lower in the 
landscape that support small mangroves; higher up are sea cliffs and wavecut platforms. The cliff 
faces exhibit well-developed laterite profiles. Some of the coastal features in the unit are 5 m above 
current high-tide levels, which is explained by changes in sea level and upwarping of the islands 
(Grimes, 1974). 


Potentially feasible dam sites occur where resistant ridges of rock that have been incised by the river 
systems outcrop on both sides of river valleys. The rocks are generally weathered to varying degrees, 
and the depth of weathering, the amount of outcrop on the valley slopes, the occurrence of 
limestone or dolomitic rocks that may contain solution features that could cause leakage, and the 
width and depth of alluvium in the base of the valley are fundamental controls on the suitability of 
the potential dam sites. 

Where the rocks are relatively unweathered and outcrop on the abutments of the potential dam site, 
less stripping will be required to achieve a satisfactory founding level for the dam. In general, where 
stripping removes the more weathered rock, it is anticipated that the Proterozoic sandstones, 
siltstones, mudstones and conglomerates will form a reasonably watertight dam foundation requiring 
conventional grout curtains and foundation preparation. 

However, because dolostones are soluble over a geological timescale, it is possible that, where they 
occur within the Proterozoic sequences, potentially leaky dam abutments and reservoir rims may be 
present, which would require specialised and costly foundation treatment such as extensive grouting. 
The extent and depth of the Cenozoic or Quaternary alluvial sands and gravels in the floor of the 
valley are also important geological controls on dam feasibility, as these materials will have to be 
removed to achieve a satisfactory founding level for the dam. 

2.2.3 Major hydrogeological provinces of the Southern Gulf catchments 

In terms of groundwater, five major hydrogeological provinces exist in the Southern Gulf catchments: 
(i) the McArthur Basin, which underlies the north-west of the catchment, (ii) the Georgina Basin, 
which overlies the McArthur Basin in the south to south-west of the catchment, (iii) the Isa Highland, 
(iv) the geological Carpentaria Basin, which rests on an erosional surface of deformed Proterozoic 
rocks of the Isa Superbasin and South Nicholson Basin, and (v) the Cenozoic Karumba Basin, which 
unconformably overlies the geological Carpentaria Basin (Figure 2-4) and alluvial plains. The broad 
major rock types associated with each geological province include igneous and sedimentary rocks 
(McArthur, South Nicholson, Georgina and geological Carpentaria basins and Isa Superbasin) and 
unconsolidated (surficial regolith) to consolidated sediments (Karumba Basin) (Figure 2-4). 

The McArthur Basin is a geological province underlain by an approximately 10 km thick sequence of 
sedimentary rocks that in places are intruded by minor igneous rocks of Precambrian age 
(Paleoproterozoic to Mesoproterozoic). The McArthur Basin extends well beyond the Southern Gulf 
catchments. In the Southern Gulf catchments, the McArthur Basin is undulating with isolated ranges 
of quartzite and igneous rocks dissected by river valleys. 

The rocks of the McArthur Basin have been intruded with dolerite, folded, faulted and uplifted, and 
subjected to long periods of erosion (both physical and chemical weathering) since they were 
formed. Most of the sedimentary and igneous rocks of the McArthur Basin have very low primary 
porosity (<2%), and their pores are very small and not interconnected. Consequently, they do not 
hold or yield much groundwater and can be impermeable across large areas. Where the upper parts 
of the sedimentary and igneous rocks are weathered and fractured, they can contain volumes of 
water that, while not large, can have local importance for stock and domestic use and community 
water supplies. 


 

Geological basins and provinces map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\11_Groundwater\4_S_Gulf\1_GIS\1_Map_docs\Gr-S-513_Geological_provinces_v04_CR.mxd 
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-4 Major geological provinces of the Southern Gulf catchments 

Source: adapted from Raymond (2018) 

The most well-known and significant intermediate- to regional-scale groundwater systems within the 
Southern Gulf catchments are hosted by the Georgina and Carpentaria basins, which underlie 
approximately 12,400 km2 of the Southern Gulf catchments. There may also be other hydrogeological 
units that are currently poorly characterised but host local- to intermediate-scale groundwater 
systems with potential to support small-scale localised irrigated agriculture opportunities (i.e. the 












Proterozoic rocks and the Bulimba Formation). However, data and information for these systems are 
very limited. 
The major hydrostratigraphic units hosted by the Georgina Basin within the Southern Gulf 
catchments are the Camooweal Dolostone, Wonarah Formation and Thorntonia Limestone. Recent 
stratigraphic drilling conducted as part of the National Drilling Initiative (Exploring for the future, n.d.) 
identified a thickness of more than 600 m of Georgina Basin sedimentary rocks (mostly limestone and 
dolostone) within the Southern Gulf catchments. 
The Camooweal Dolostone is the shallowest of the Georgina Basin’s more prospective 
hydrogeological units in the Southern Gulf catchments. It is composed of dolostone and dolomitic 
limestone. The Wonarah Formation of the Georgina Basin also occurs in the south-west portion of 
the Southern Gulf catchments and merges laterally into the Anthony Lagoon Formation (the Wiso 
Basin stratigraphic equivalent). It is predominantly composed of silty dolostone with interbedded 
(minor) dolomitic and calcareous mudstone and siliciclastic mudstone. Very little information exists 
for the Wonarah Formation in the Southern Gulf catchments, and it therefore remains unclear if it 
exhibits the same hydraulic characteristics as its stratigraphic equivalents in adjacent areas. The 
Thorntonia Limestone is composed mostly of dolostone and dolomitic limestone. The limestone 
aquifers occur mostly in the NT, but within the Southern Gulf catchments they also outcrop or 
subcrop in far western Queensland and host a significant regional groundwater system. 
The sedimentary sequences of the geological Carpentaria Basin are mostly sandstone, siltstone, 
mudstone and claystone. They have a combined thickness of up to approximately 600 m in the 
Southern Gulf catchments and thicken significantly offshore. Within the Southern Gulf catchments, 
the geological Carpentaria Basin rocks overlie the formations of the McArthur Basin in the north-east 
and the Isa Superbasin and South Nicholson Basin in the east and south-east (Figure 2-4). Most of the 
rocks of the geological Carpentaria Basin have very low primary porosity and are considered 
aquitards. However, the extensive and porous sandstones of the GRF are considered a productive 
aquifer and the Normanton Formation is considered an aquifer or partial aquifer. Groundwater 
within the GRF is under artesian pressure in some parts of the Southern Gulf catchments (e.g. at the 
Burketown bore). 
Consisting of lacustrine, fluvial and, to a lesser extent, shallow-shelf marine sediments, the 
widespread Cenozoic sediments of the Karumba Basin unconformably overlie the Carpentaria 
Sub-basin of the GAB. Within the Southern Gulf catchments, Cenozoic sediments are expected to 
reach a maximum thickness of 40 m (north of Doomadgee), and the most productive aquifer is 
expected to correspond to the basal section of the Bulimba Formation, which is composed mostly of 
fine-grained quartzose sediments. 
Overlying the Karumba Basin are the youngest sediments in the catchments: the alluvial sands, silts 
and gravels associated with the beds, channels and floodplains of the Leichhardt, Nicholson and 
Gregory rivers, and Settlement Creek and their tributaries. Only a few groundwater bores intersect 
the youngest alluvial aquifers; these existing bores suggest that the alluvial sediments are generally 
relatively shallow (drilled to depths of up to approximately 25 m). 
30 | Water resource assessment for the Southern Gulf catchments 


2.3 Soils of the Southern Gulf catchments 

2.3.1 Introduction 

Soils in a landscape occur as complex patterns resulting from the interplay of five key factors: parent 
material, climate, organisms, topography and time (Fitzpatrick, 1986; Jenny, 1941). Consequently, 
soils can be highly variable across a landscape. Different soils have different attributes that determine 
their suitability for growing different crops and guide how they need to be managed. The distribution 
of these soils and their attributes closely reflects the geology and landforms of the catchments. 
Hence, data and maps of soil and soil attributes that provide a spatial representation of how soils 
vary across a landscape are fundamental to regional-scale land use planning. 

This section briefly describes the spatial distribution of soil generic groups (Section 2.3.2) and soil 
attributes (Section 2.3.3) in the Southern Gulf catchments. The management considerations for 
irrigated agriculture are also summarised in Table 2-1. Maps showing the suitability of different areas 
for different crops under different irrigation types in different seasons are presented in Chapter 4. 

Unless otherwise stated, the material in Section 2.3 is based on findings described in the companion 
technical report on digital soil mapping and land suitability (Thomas et al., 2024). Soils and their 
attributes were collected and described according to Australian soil survey standards (National 
Committee on Soil and Terrain, 2009). 

2.3.2 Soil characteristics 

The soils of the Southern Gulf catchments are presented in a soil generic group (SGG) classification 
(Figure 2-5; Table 2-1; Table 2-2). These groupings provide a means of aggregating soils with broadly 
similar properties and management considerations. 

The distinctive groupings have different potential for agriculture: some have almost no potential (e.g. 
the shallow and/or rocky soils – SGG 7) and some have moderate to high potential (e.g. the cracking 
clay soils – SGG 9), assuming other factors such as flooding and the amount of salt in the profile are 
not limiting. 

The SGGs were designed to simultaneously cover a number of purposes: (i) to be descriptive so as to 
assist non-expert communication regarding soil and resources, (ii) to be relatable to agricultural 
potential, and (iii) to align, where practical, to the Australian Soil Classification (ASC) (Isbell and 
CSIRO, 2016). Soil generic groups were first used in Queensland to facilitate extension in the sugar 
industry, and they have been modified to suit the range of soils encountered in the Assessment area. 

The soil groups and soil characteristics presented below can be viewed in the context of their 
relationship to physiographic units within the catchment (Figure 2-3; Table 2-1). These physiographic 
units serve as a useful framework to understand the extent of different SGGs because each unit is 
derived from a distinct group of lithologies and landforms that give rise to a particular set of soil 
types and geomorphic patterns. 




Soil generic group map and locations
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\4_S_Gulf\1_GIS\1_Map_Docs\CR-S-512-Ch4_SGG_v1_Arc10_8.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-5 The soil generic groups (SGGs) of the Southern Gulf catchments produced by digital soil mapping 

The inset map shows the data reliability, which for SGG mapping is based on the confusion index as described in the 
companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). Labels on the map relate to 
the locational description of soils later in this Section (2.3.2). 


Table 2-1 Soil generic groups (SGGs), descriptions, management considerations and correlations to Australian Soil 
Classification (ASC) for the Southern Gulf catchments 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
The Southern Gulf catchments contain soils from nine of the ten SGGs (Figure 2-5); peaty soils (SGG 
5) are not found. Only two of the nine SGGs occupy more than 10% of the area, and together these 
soils represent 78% of the study area (Table 2-2). They are the shallow and/or rocky soils, which are 
associated with uplands and plateaux (SGG 7, 55.9%), and the cracking clay soils found on the Barkly 
Tableland and the Armraynald Plain (SGG 9, 22.5%). Brown, yellow and grey sandy soils (SGG 6.2) 
make up 7.6% of the catchment and seasonally or permanently wet soils (SGG 3) another 6.0%, 
both being common on the Doomadgee Plain.
34 | Water resource assessment for the Southern Gulf catchments 


Table 2-2 Area and proportions covered by each soil generic group (SGG) in the Southern Gulf catchments 

SGG 

SOIL DESCRIPTION 

AREA 
(ha) 

% OF ASSESSMENT 
AREA (ROUNDED) 

1.1 

Sand or loam over relatively friable red clay subsoils 

49,000 

<1 

1.2 

Sand or loam over relatively friable brown, yellow and 
grey clay subsoils 

59,000 

<1 

2 

Friable non-cracking clay or clay loam soils 

378,000 

3 

3 

Seasonally or permanently wet soils 

675,500 

6 

4.1 

Red loamy soils 

58,300 

<1 

4.2 

Brown, yellow and grey loamy soils 

202,100 

2 

5 

Peaty soils 

0 

0 

6.1 

Red sandy soils 

168,000 

2 

6.2 

Brown, yellow and grey sandy soils 

830,300 

8 

7 

Shallow and/or rocky soils 

6,057,700 

56 

8 

Sand or loam over sodic clay subsoils 

25,200 

<1 

9 

Cracking clay soils 

2,434,800 

23 

10 

Highly calcareous soils 

1,700 

<1 

Total 



10,820,000 





The soils with some of the greatest agricultural potential in the Assessment area are the cracking 
clays or Vertosols (SGG 9), which cover 2,434,800 ha. Both the Armraynald Plain (C1 in Figure 2-5) 
and Barkly Tableland (C2) are extensive natural grasslands with few trees, reflecting the cracking 
nature of the soils (Figure 2-6). These soils are medium to heavy clays that crack when dry and swell 
when wet, reducing water permeability. They have a self-mulching clay surface, deep to very deep 
(1.2 to 1.5 m) effective rooting depth, and the clay texture means the soils have a very high 
(>220 mm) soil available water capacity (AWC). The clays soils of the Armraynald Plain (C1) are 
imperfectly drained and can have high salt levels within the profile, whereas the Barkly Tableland 
soils on the uplands (C2) are moderately well drained and gravel is common. On the Armraynald 
Plain, soils are suited to a variety of vegetables (but not root crops), rice (Oryza spp.), sugarcane 
(Saccharum officinarum) and dry-season grain, forage, pulse crops, sweetcorn (Zea mays convar. 
saccharata var. rugosa) and cotton (Gossypium spp.). On the Barkly Tableland, soils are suited to 
trickle-irrigated mangoes (Mangifera indica) and vegetables as well as wet-season cotton, grain and 
forage crops. 

Along the middle reaches of the Leichhardt River (F1 in Figure 2-5), a moderately well-drained, friable 
non-cracking clay or clay loam soil (SGG 2; 295,460 ha on the mainland) has formed on the 
floodplains (Figure 2-7). The soils are moderately well to well drained and have a weakly structured, 
fine sandy to loam surface soil over a structured sandy clay loam or silty clay subsoil. Effective rooting 
depth is very deep (>1.5 m) and AWC is moderate (>160 mm). On Mornington Island (F2), this soil is 
shallower with varying amounts of ironstone gravel reducing the AWC. 


 

Soil or landscape photo 
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Figure 2-6 Cracking clay (brown Vertosol; SGG 9) Mitchell grass (Astrebla spp.) downs with whitewood (Elaeocarpus 
sp.) and gutta percha (Palaquium spp.) on the Armraynald Plain physiographic unit, east of the Leichhardt River 

Photo: CSIRO 

 


Soil or landscape photo 
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Figure 2-7 Brown Dermosol (SGG 2) buffel grass (Cenchrus ciliaris) open woodland with silver leaf box (Eucalyptus 
pruinosa) on the Armraynald Plain physiographic unit in the middle reaches of the Leichhardt River 

Photo: CSIRO 

 


On the floodplains of the upper lowlands of the Leichhardt River (U1 in Figure 2-5), a well-drained, 
sandy loam over a structured red clay subsoil (SGG 1.1; 49,100 ha) has formed. This soil also has a 
very deep (>1.5 m) effective rooting depth and a high (>180 mm) AWC. 

Sandy soils (SGG 6) are found on the Doomadgee Plain (S1 in Figure 2-5), on Donors Plateau (S2) 
(Figure 2-8), in the Gulf Fall (S3) and on the elevated terraces north of the Nicholson River (S4) in the 
Armraynald Plain, covering 996,660 ha on the mainland. The Doomadgee Plain soils (S1) are brown 
sands (SGG 6.2) that are well drained and commonly limited by ferricrete rock within 0.6 to 1 m of 
the soil surface. The soil has a very low AWC (25 to 60 mm), depending on soil depth. On Donors 
Plateau (S2), the yellow sandy soils (SGG 6.2) are deeper and have a high ironstone gravel content 
throughout the profile reducing AWC. In the Gulf Fall (S3), the brown (SGG 6.2) and red (SGG 6.1) 
deep sands occur in the subcatchments of Buddycurrawa, Breakfast, Running and Sandy creeks, and 
the upper parts of the catchment of the Nicholson River. Near the Doomadgee township (S4), soils 
are predominantly red sands (SGG 6.1) that are well drained but have a low AWC (60 to 100 mm). 

 

Soil or landscape photo 
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Figure 2-8 Red sandy soil (SGG 6.1) open woodland of Darwin box (Eucalyptus tectifica), bauhinia (Bauhinia spp.) and 
Cooktown ironwood (Erythrophleum chlorostachys) near Doomadgee on the Armraynald Plain physiographic unit north 
of the Nicholson River 

Photo: CSIRO 

Loamy soils (SGG 4) have formed along the Nicholson River (K1 in Figure 2-5) and on the Doomadgee 
(K2) and Cloncurry (K3) plains, and in other isolated areas. They are either red (SGG 4.1; 58,300 ha) 
well drained or brown (SGG 4.2; 202,100 ha) moderately well drained soils, and they have a high 
AWC (>170 mm). On the Doomadgee Plain along Westmoreland Road (K2) are brown, yellow and 
grey sandy clay loams over sandy clays (SGG 4.2) that are poorly to moderately well drained. Soils 
vary in depth depending on the depth of the underlying rock and have a low to moderate AWC (70 to 
150 mm). The red loamy soils (SGG 4.1) on the Cloncurry Plain (K3) are shallower and sandier and 
commonly have gravel and ironstone throughout the profile; accordingly, these soils have a lower 
AWC. Irrigation potential is limited to spray- and trickle-irrigated crops on the moderately deep to 
deep (>1 m) soils. 


Seasonally or permanently wet soils (SGG 3; 648,510 ha on the mainland) occur on local alluvia along 
creeks and in swamps, particularly between Lilly and Moonlight creeks on the Doomadgee Plain (W1 
in Figure 2-5), and the tidal flats and wetlands of the Karumba Plain (W2). The soils are very poorly 
drained. 

Texture contrast soils that have sodic clay subsoils (SGG 8; 25,200 ha on the mainland) are minor 
areas occurring on Nineteen Mile Creek (D1 in Figure 2-5), a tributary of the Leichhardt River, and on 
a meander plain just upstream of the Gregory–Nicholson River junction (D2). 

Shallow soils (<0.25 m depth) or rocky soils (>50% rock) (SGG 7; 6,049,320 ha on the mainland) occur 
extensively in more than half of the Assessment area (Table 2-2), particularly in the mountainous Isa 
Highland, Gulf Fall, Dissected Barkly Tableland and Donors Plateau physiographic units. 

More detail on the soils and their relationship to the physiographic units shown in Figure 2-3 can be 
found in the companion technical report on digital soil mapping and land suitability (Thomas et al., 
2024). 




Figure 2-9 Level to gently undulating cracking clay soils of the Armraynald Plain suitable for broadacre irrigation 

Photo: CSIRO – Nathan Dyer 




2.3.3 Soil attribute mapping 

Using a combination of field sampling (Figure 2-10) and digital soil mapping techniques, the 
Assessment mapped 18 attributes affecting the agricultural and aquaculture suitability of soil for the 
Southern Gulf catchments, as described in the companion technical report on digital soil mapping 
and land suitability (Thomas et al., 2024). 

Descriptions and maps are presented below for six key attributes: 

•surface soil pH
•soil thickness
•soil surface texture
•permeability
•available water capacity in the upper 100 cm of the soil profile (referred to as AWC 100)
•surface rockiness.


An important feature of each predicted attributes map is the companion reliability map showing the 
relative confidence in the accuracy of the attribute predictions. Note that mapping is only provided 
here for regional-scale assessment. Areas of high reliability allow users to be more confident in the 
accuracy of mapping, whereas areas of low reliability show where users should be cautious. 



Soil or landscape photo 
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Figure 2-10 Soil profile of the brown Vertosol (SGG 9) sampled on the Armraynald Plain physiographic unit east of the 
Leichhardt River 
Topsoil is on the left-hand side of the lower 1 m of core tray and the subsoil in the top core tray. The sample core was 
1.5 m deep. 
Photo: CSIRO 




Surface soil pH 

The pH value of a soil reflects the extent to which the soil is alkaline or acidic, which affects the 
extent to which nutrients are available to plants for growth. Surface soil pH is the pH in the top 10 cm 
of the soil. For the majority of plant species, most soil nutrients are available when the pH range is 
5.5 to 6.5. Nutrient imbalances are common for soils with pH greater than 8.5 or less than 5.5 and 
can lead to toxicity problems. However, almost all of the study area is in the pH range 5.5 to 8.5 
(Figure 2-11), which is within the acceptable agronomic threshold (Peverill et al., 1999). Areas in the 
acid-to-neutral range (pH 5.5 to 7.0) are more associated with the sandier surface soils (Figure 2-13) 
dominated by shallow and/or rocky soils (SGG 7), red sandy soils (SGG 6.1) and brown, yellow and 
grey sandy soils (SGG 6.2). Sandier soils tend to be more acidic because of increased soil permeability 
(Figure 2-14) and have higher leaching rates of neutralising soil components. Coarse-textured soils 
also tend to have lower buffering capacity by virtue of lower cation exchange capacity supplied by 
clay minerals and organic matter. The more alkaline soils (pH 7.0 to 8.5) are associated with soils with 
higher clay content, especially the cracking clay soils (SGG 9) and some areas of seasonally or 
permanently wet soils (SGG 3). 

Mapping reliability is generally low to moderate across the Assessment area, being lowest in the 
Dissected Barkly Tableland and the Karumba Plain physiographic units and in areas of the Gulf Fall 
unit where lack of data produces less reliable results. Mapping reliability is stronger for the 
Doomadgee Plain physiographic unit, indicating good data correlation. 



Soil surface pH map 
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Figure 2-11 (a) Surface soil pH (top 10 cm) of the Southern Gulf catchments as predicted by digital soil mapping and (b) 
reliability of the prediction 




Soil thickness 

Soil thickness defines the potential root space and the amount of soil from which plants obtain their 
water and nutrients. The deeper soils dominate the lowlands and Wellesley Islands and the western 
margins of the uplands (Figure 2-12). The lowland deeper soils are associated with cracking clay soils 
(SGG 9) of the Cloncurry Plain and Armraynald Plain, and on the Doomadgee Plain with significant 
areas of brown, yellow and grey sandy soils (SGG 6.2), and brown, yellow and grey loamy soils (SGG 
4.2). Additionally, the Karumba Plain is dominated by seasonally or permanently wet soils (SGG 3) 
that are also generally deep. In upland areas, there are extensive areas of cracking clay soils (SGG 9) 
on the Barkly Tableland physiographic unit, and the Gulf Fall unit has large areas of deep red sandy 
soils (SGG 6.1) and deep brown, yellow and grey sandy soils (SGG 6.2) on the western margins of the 
Dissected Barkly Tableland and Gulf Fall physiographic units. Deep friable non-cracking clay or clay 
loam soils (SGG 2) dominate Mornington Island. Shallow and/or rocky soils (SGG 7) dominate the Isa 
Highland physiographic unit and the eastern areas of the Dissected Barkly Tableland and Gulf Fall 
units. 

Soil thickness mapping is least reliable along the coastal fringes and the Wellesley Islands, as these 
areas have few data points, and most reliable in the uplands, especially the Isa Highland 
physiographic unit where there is less variation in soil thickness across the landscape. 

 

Soil thickness map 
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Figure 2-12 (a) Soil thickness of the Southern Gulf catchments as predicted by digital soil mapping and (b) reliability of 
the prediction 

 


Soil surface texture 

Soil texture refers to the proportion of sand, silt and clay particles that make up the mineral fraction 
of a soil. Surface texture influences soil water-holding capacity, soil permeability, soil drainage, water 
and wind erosion, workability and soil nutrient levels. Light-textured soils are generally those high in 
sand, and heavy-textured soils are dominated by clay. The clayey surface soils represent a large 
proportion of the Assessment area and dominate the Barkly Tableland, the Dissected Barkly 
Tableland, the Armraynald Plain, the Karumba Plain and the Donors Plateau physiographic units 
(Figure 2-13). These soils are mainly cracking clay soils (SGG 9) and seasonally or permanently wet 
soils (SGG 3). Sandy surface soils co-dominate the area and are mainly represented by shallow and/or 
rocky soils (SGG 7) and the brown, yellow and grey sandy soils (SGG 6.2) of the Isa Highland and 
Doomadgee Plain physiographic units. Sandy-textured surface soils like SGG 7 are also strongly 
represented in the Donors Plateau physiographic unit. Loamy soil surfaces are associated mainly with 
SGG 7 soils located in the Gulf Fall and Isa Highland physiographic units, although their contribution 
across the Assessment area is minor. 

Mapping reliability of soil surface texture tends to be lower in the areas of higher relief than in the 
plains. The upland Isa Highland and Dissected Barkly Tableland physiographic units have particularly 
low reliability, reflecting the variability of surface textures across the landscape. Reliability is highest 
in the Doomadgee Plain and Armraynald Plain physiographic units in the lowlands and the Barkly 
Tableland physiographic unit in the uplands, reflecting more consistent surface textures within these 
units. 

 

Soil surface texture map 
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-13 (a) Soil surface texture of the Southern Gulf catchments as predicted by digital soil mapping and (b) 
reliability of the prediction 

 


Permeability 

The permeability of the profile is a measure of how easily water moves through a soil. Flood and 
furrow irrigation is most successful on soils with low and very low permeability, which reduces root 
zone drainage (i.e. water passing below the root zone of a plant), rising watertables and nutrient 
leaching. Spray or trickle irrigation is more efficient than flood and furrow irrigation on soils with 
moderate to high permeability. The Assessment area is dominated by moderately permeable soils 
and, to a lesser extent, slowly permeable soils (Figure 2-14). The latter correlate with patterns of 
cracking clay soils (SGG 9) of the Armraynald Plain and Barkly Tableland physiographic units. Highly 
permeable soils are associated with brown, yellow and grey loamy soils (SGG 6.2) of the Doomadgee 
Plain unit, areas of the Gulf Fall unit, and a part of the Cloncurry Plain unit on the eastern margin of 
the Assessment area dominated by shallow and/or rocky soils (SGG 7). 

Generally, mapping reliability in the Assessment area is low where areas have limited data and on the 
Doomadgee Plain where permeability is quite variable across the landscape. Higher map reliability 
occurs on the Armraynald Plain physiographic unit where soils have a more consistent permeability. 

 

Soil permeability map 
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Figure 2-14 (a) Soil permeability of the Southern Gulf catchments as predicted by digital soil mapping and (b) reliability 
of the prediction 

 


Available water capacity to 100 cm 

AWC 100 is the maximum volume of water that the top 100 cm of soil can hold for plant use. The 
higher the AWC 100 value, the greater the capacity of the soil to supply plants with water. For 
irrigated agriculture, it is one factor that determines irrigation frequency and the volume of water 
required to wet up the soil profile. Soils with low AWC 100 require more frequent watering and lower 
volumes of water per irrigation. For dryland agriculture, AWC 100 determines the capacity of crops to 
grow and prosper during dry spells. Patterns of AWC 100 (Figure 2-15) closely correlate with soil 
thickness patterns (Figure 2-12) and surface soil textures (Figure 2-13). While these soil attributes do 
not definitively indicate subsurface soil textures and consequently water-holding capacity, the 
correlation shows the largest AWC values are found where soils are deep and are clay rich, especially 
the Armraynald Plain, Cloncurry Plain and Barkly Tableland physiographic units. 

Mapping reliability for AWC is generally highest in upland areas of the Gulf Fall and northern areas of 
Isa Highland physiographic units. It is least reliable in the Barkly Tableland physiographic unit having 
fewer measurements. 

 

Soil available water capacity to 1m map 
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-15 (a) Available water capacity in the upper 100 cm of the soil profile (AWC 100) of the Southern Gulf 
catchments as predicted by digital soil mapping and (b) reliability of the prediction 

 


Rockiness 

The rockiness of the soil affects agricultural management and the growth of some crops, particularly 
root crops. Coarse fragments (e.g. pebbles, gravel, cobbles, stones and boulders), hard segregations 
and rock outcrops in the plough zone can damage and/or interfere with the efficient use of 
agricultural machinery. Surface gravel, stone and rock are particularly important and can interfere 
significantly with planting, cultivation and harvesting machinery used for root crops, small crops, 
annual forage crops and sugarcane. The rocky soil surfaces (Figure 2-16) closely coincide with the 
shallow and/or rocky soils (SGG 7). 

Overall, the reliability of mapping is high (good correlation of data as areas are either consistently 
rocky or consistently rock-free), although relatively localised areas of lower reliability are found in 
SGG 7 soil areas, reflecting a lack of data. 

 

Soil rockiness map 
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-16 (a) Surface rockiness in soils of the Southern Gulf catchments represented by presence or absence as 
predicted by digital soil mapping and (b) reliability of the prediction 

 


2.4 Climate of the Southern Gulf catchments 

2.4.1 Introduction 

Weather, which is defined as short-term atmospheric conditions, is the key source of uncertainty 
affecting hydrology and crop yield. It influences the rate and vigour of crop growth, and catastrophic 
weather events can result in extensive crop losses. Climate is defined as weather of a specific region 
averaged over a long period of time. Key climate parameters controlling plant growth and crop 
productivity include rainfall, temperature, radiation, humidity, and wind speed and direction. 

Of all the climate parameters affecting hydrology and agriculture in water-limited environments, 
rainfall is usually the most important. Rainfall is the main determinant of runoff and recharge and is a 
fundamental requirement for plant growth. For this reason, reporting of climate parameters is 
heavily biased towards rainfall data. Other climate variables affecting crop yield are discussed in the 
companion technical report on climate (McJannet et al., 2023). Climate data presented in this report 
were calculated using SILO (Scientific Information for Land Owners) climate data surfaces (Jeffrey et 
al., 2001) unless stated otherwise. Very few climate data are available in the region before 1890, 
therefore the 132-year period from 1 September 1890 to 31 August 2022 is used in the analysis 
presented below. 

Unless otherwise stated, the material in Section 2.4 is based on findings described in the companion 
technical report on climate (McJannet et al., 2023). 

2.4.2 Weather patterns over the Southern Gulf catchments 

The Southern Gulf catchments are characterised by distinctive wet and dry seasons (Figure 2-17) due 
to their location in the Australian summer monsoon belt. During the build-up months (typically 
September to December), the Southern Gulf catchments typically experience low-level easterly 
winds, which can carry pockets of dry or humid air and result in short-lived thunderstorm activity 
under favourable conditions. 

Over inland areas of the Southern Gulf catchments, storms form more frequently during the 
afternoon because of increased air temperature, which enhances instability and leads to convective 
cloud formation. Storms also form more readily near the heat trough that is a semi-permanent 
feature over inland Queensland (predominantly located south of the catchment) during late spring 
and summer months. There is also a high incidence of thunderstorms in the Southern Gulf 
catchments where sea breeze convergence and/or boundaries act as a trigger. Thunderstorms show 
a strong diurnal variation, with most occurring during the afternoon and early evening. Dynamic 
forcing can cause thunderstorms to develop or persist well beyond the normal diurnal cycle, and if 
the dynamics are strong enough, thunderstorms can occur at any time. 

In the Southern Gulf catchments, convection and rain from sea breeze convergence typically occur 
just inland from the coast from early afternoon in the warmer months. Rain can continue overnight 
and into the following morning if conditions are favourable, particularly if there is a moisture feed 
from a strong easterly nocturnal jet stream. During the day, the air over land warms and rises, 
resulting in lower pressure at the surface. Air flows from the Gulf of Carpentaria waters towards the 
land to fill this area of lower pressure, resulting in the sea breeze, which can converge with the 


usually south-easterly synoptic winds. During the wet season, the convergence of persistent easterly 
winds and broader synoptic north-westerly winds over the Gulf of Carpentaria may trigger storms 
over the coast after sunset. This phenomenon is most pronounced in the near-coastal areas of the 
catchment. 

 

Historical climate, map
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For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
Figure 2-17 Historical rainfall, potential evaporation and rainfall deficit 

Median (a) annual, (b) wet-season and (c) dry-season rainfall; median (d) annual, (e) wet-season and (f) dry-season 
potential evaporation; and median (g) annual, (h) wet-season and (i) dry-season rainfall deficit in the Southern Gulf 
catchments. Rainfall deficit is rainfall minus potential evaporation. 

 


The mean annual rainfall, averaged over the Southern Gulf catchments for the 132-year historical 
period (1 September 1890 to 31 August 2022), is 602 mm. Rainfall totals are highest near the coast 
and decline in a southerly direction (Figure 2-17). This is because the more northerly regions of the 
catchments receive more wet-season rainfall as a result of active monsoon episodes. The Southern 
Gulf catchments are relatively flat, so there is no noticeable topographic influence on climate 
parameters such as rainfall or temperature. 

Approximately 94% of the rain falls in the Southern Gulf catchments during the wet-season months 
(1 November to 30 April). Figure 2-17 shows the spatial distribution of rainfall over the year and 
during the wet and dry seasons. Median wet-season rainfall exhibits a very similar spatial pattern to 
median annual rainfall. Median dry-season rainfall is highest in the most southern part of the 
Leichhardt catchment and lowest near the coast. The highest monthly rainfall totals typically occur 
during January and February (Figure 2-18). 

Tropical cyclones and tropical lows contribute a considerable proportion of total annual rainfall, but 
the actual amount is highly variable from one year to the next (see the companion technical report 
on climate (McJannet et al., 2023)) since tropical cyclones do not affect the Southern Gulf catchments 
in more than half of years. For the 53 tropical cyclone seasons from 1969–70 to 2021–22, 60% of 
seasons registered no tropical cyclones tracking over the Southern Gulf catchments, 36% experienced 
one tropical cyclone and 4% experienced two (BOM, 2023). 

2.4.3 Potential evaporation and potential evapotranspiration 

Evaporation is the process by which water is lost from open water, plants and soils to the 
atmosphere; it is a ‘drying’ process. It has become common usage to also refer to this as 
evapotranspiration. 

Evaporation primarily affects the potential for irrigation by influencing: 

• runoff and deep drainage and, hence, the ability to fill water storages (Section 2.5) 
• crop water requirements (Section 4.3) 
• losses from water storages (Section 5.3). 


Potential evaporation (PE), or potential evapotranspiration (PET), is defined as the amount of 
evaporation that would occur if an unlimited source of water was available. The Southern Gulf 
catchments have a mean annual PE of 1900 mm (over the period 1890 to 2022) (Figure 2-17). 
Evaporation is high all year round, but exhibits a strong seasonal pattern, ranging from about 
200 mm/month during November and December to about 100 mm/month during the middle of the 
dry season (June) (Figure 2-19). 

Preliminary estimates of mean annual (or seasonal) irrigation demand and net evaporation from 
water storages are sometimes calculated by subtracting the mean annual (or seasonal) PE from the 
mean annual (or seasonal) rainfall. This is commonly referred to as the mean annual (or seasonal) 
rainfall deficit (Figure 2-17). The mean annual rainfall deficit, or mean annual net evaporative water 
loss, in the Southern Gulf catchments is about 1305 mm, and the deficit increases with distance from 
the coast. 

Two common methods for characterising climates are the United Nations Environment Program 
aridity index and the Köppen–Geiger classification (Köppen, 1936; Peel et al., 2007). The aridity index 


classifies the Southern Gulf catchments as mainly ‘Semi-arid’, and the Köppen–Geiger classification 
classifies it as ‘Arid hot steppe’ (see the companion technical report on climate (McJannet et al., 
2023)). 

2.4.4 Variability and long-term trends in rainfall and potential evaporation 

Climate variability is a natural phenomenon that can be observed in many ways, for example, 
warmer-than-average dry seasons or low- and high-rainfall wet seasons. Climate variability can also 
operate over long-term cycles of decades or more. Climate trends represent long-term, consistent 
directional changes such as warming or increasingly higher mean rainfall. Separating climate 
variability from climate change is difficult, especially when comparing climate on a year-to-year basis. 

In the Southern Gulf catchments, 94% of the rain falls during the wet season (November to April). The 
highest monthly rainfall in the Southern Gulf catchments typically occurs in January or February 
(Figure 2-18). The months with the lowest rainfall are June to September. In Figure 2-18, the blue 
shading (labelled ‘A range’) represents the range under Scenario A (i.e. the historical climate from 
1 September 1890 to 31 August 2022). The upper limit of the A range is the value at which monthly 
rainfall (or PE in Figure 2-19) is exceeded during only 10% of years (10% exceedance). The lower limit 
of the A range is the value at which monthly rainfall (or PE) is exceeded during 90% of years (90% 
exceedance). The difference between the upper and lower limits of the A range provides a measure 
of the potential variation in monthly values from one year to the next. 

PE also exhibits a seasonal pattern (Figure 2-19): mean PE is about 210 mm during December and it is 
at its lowest during June (100 mm). Months in which PE is high correspond to those months where 
the demand for water by plants is also high. Mean wet-season and dry-season PE in the Southern 
Gulf catchments are shown in Figure 2-17. Compared to rainfall, the variation in monthly PE from one 
year to the next is small (Figure 2-19). 

Relative to other catchments in southern and northern Australia, the Southern Gulf catchments have 
high variability in rainfall from one year to the next. This variability is demonstrated for four locations 
in the Southern Gulf catchments in Figure 2-18. The highest annual rainfall at Mount Isa (948 mm) 
occurred in the 1894–95 wet season; it was more than seven times the lowest annual rainfall 
(127 mm in 1925–26) and more than twice the median annual rainfall value (396 mm). The 10-year 
running mean provides an indication of the sequences of wet or dry years (i.e. variability at decadal 
timescales). For an annual time series, the 10-year running mean is the mean of the past 10 years of 
data, including the current year. Using Mount Isa as an example, the 10-year running mean varied 
from 291 to 562 mm. Figure 2-18 illustrates that the period between 2000 and 2010 was wetter than 
average. Under Scenario A, PE exhibits much less inter-annual variability than rainfall at the four 
demonstration locations (Figure 2-19). 


 

Rainfall, graph
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Figure 2-18 Historical monthly rainfall (left) and time series of annual rainfall (right) in the Southern Gulf catchments at 
Mount Isa, Doomadgee, Gregory and Burketown 

‘A range’ is the 10% to 90% exceedance values of monthly rainfall. Note: the ‘A mean’ line is directly under the ‘A median’ 
line in some months in these figures. The solid blue line in the right column is the 10-year running mean. 


 

Potential evaporation, graph
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Figure 2-19 Historical monthly potential evaporation (PE) (left) and time series of annual PE (right) in the Southern Gulf 
catchments at Mount Isa, Doomadgee, Gregory and Burketown 

‘A range’ is the 10% to 90% exceedance values of monthly rainfall. Note: the ‘A mean’ line is directly under the ‘A median’ 
line in these figures. The solid blue line in the right column is the 10-year running mean 


The coefficient of variation (CV) provides a measure of the variability of rainfall from one year to the 
next. CV is calculated as the standard deviation of mean annual rainfall divided by the mean annual 
rainfall, and the larger the CV value, the larger the variation in annual rainfall relative to a location’s 
mean annual rainfall. Figure 2-20a shows the CV of annual rainfall for rainfall stations with a 
long-term record around Australia. Figure 2-20b shows that the inter-annual variation in rainfall in 
the Southern Gulf catchments is moderately high for northern Australia catchments and high 
compared to stations in southern Australia with similar mean annual rainfall. 

 (a) 

(b) 





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Figure 2-20 (a) Coefficient of variation (CV) of annual rainfall and (b) the CV of annual rainfall plotted against mean 
annual rainfall for 99 rainfall stations around Australia 
(a) The grey polygon indicates the extent of the Southern Gulf catchments. (b) The rainfall station in the Southern Gulf 
catchments is indicated by a red symbol. The light blue diamonds indicate rainfall stations from the rest of northern 
Australia (RoNA), and hollow squares indicate rainfall stations from southern Australia (SA).
Furthermore, Petheram et al. (2008) observed that the inter-annual variability of rainfall in northern 
Australia is about 30% higher than that observed at rainfall stations from the rest of the world for the 
same type of climate as northern Australia. Hence, caution should be exercised before drawing 
comparisons between the agricultural potential of the Southern Gulf catchments and other parts of 
the world with a similar climate. 
Several factors are driving this high inter-annual variation in Australia’s climate, including the El Niño 
– Southern Oscillation (ENSO), the Indian Ocean Dipole, the Southern Annular Mode, the 
Madden–Julian Oscillation and the Interdecadal Pacific Oscillation.
Of these influences, the ENSO phenomenon is considered to be the primary source of global climate 
variability over the 2- to 6-year timescale (Rasmusson and Arkin, 1993), and it is reported to be a 
significant cause of climate variability for much of eastern and northern Australia. One of the modes 
of ENSO, El Niño, has come to be a term synonymous with drought in the western Pacific and eastern 
and northern Australia (though El Niño does not necessarily mean a ‘drought’ will occur). Rainfall 
stations along eastern and northern Australia have been observed to have a strong correlation (0.5 to 
0.6) with the Southern Oscillation Index (SOI), a measure of the strength of ENSO, during spring, 
suggesting that ENSO plays a key role in between-year rainfall variability (McBride and Nicholls, 
1983). 
52 | Water resource assessment for the Southern Gulf catchments 


Another known impact of ENSO in northern Australia is the tendency for the onset of useful rains 
after the dry season to be earlier than normal in La Niña years and later than normal in El Niño years. 
For all years between 1890 and 2022, the mean rainfall onset date (defined as being the date on 
which 50 mm of rain has accumulated after the dry season) for the Southern Gulf catchments is the 
last 10 days of October (see the companion technical report on climate (McJannet et al., 2023)). The 
mean SOI for the September to December period in each year was used to determine whether given 
years were in negative (SOI < −8, El Niño), positive (SOI > 8, La Niña), or neutral SOI (−8 < SOI < 8). 
Using this method, in El Niño, neutral and La Niña years, respectively, the median rainfall onset dates 
for the Southern Gulf catchments are the middle of January, early January and early December. 

Trends 

Previously, CSIRO (2009a) found that rainfall in northern Australia between 1997 and 2007 was 
statistically different to that between 1930 and 1997. In other work, Evans et al. (2014) found a 
strong relationship between monsoon active periods and the Madden–Julian Oscillation, and that the 
increasing rainfall trend observed at Darwin Airport was related to increased frequency of active 
monsoon days rather than increased intensity during active periods. 

Runs of wet and dry years 

The rainfall-generating systems in northern Australia and their modes of variability combine to 
produce irregular runs of wet and dry years. In particular, length and magnitude (intensity) of dry 
spells strongly influence the scale, profitability and risk of water-resource-related investments. The 
Southern Gulf catchments are likely to experience dry periods of similar severity to many centres in 
the Murray–Darling Basin and on the east coast of Australia. 

The Southern Gulf catchments are characterised by irregular periods of consistently low rainfall when 
successive wet seasons fail, in addition to the typical annual dry season. Runs of wet years and dry 
years occur when consecutive years of rainfall occur that are above or below the median, 
respectively. These are shown in Figure 2-21 at Mount Isa, Doomadgee, Gregory and Burketown 
stations as annual differences from the median rainfall. A run of consistently dry years may be 
associated with drought (though an agreed definition of drought continues to be elusive). Analysis of 
annual rainfall at stations in the Southern Gulf catchments indicates equally long runs of wet and dry 
years and nothing unusual about the length of the runs of dry years. 




A graph of numbers and lines
Description automatically generated with medium confidence
Figure 2-21 Runs of wet and dry years at Mount Isa, Doomadgee, Gregory and Burketown 

Wet years are shown by the blue columns and dry years by the red columns. 


Palaeoclimate records for northern Australia 

The instrumental record of climate data is very short in a geological sense, particularly in northern 
Australia, so a brief review of palaeoclimate data is provided. The literature indicates that 
atmospheric patterns approximating the present climate conditions in northern Australia (e.g. the 
Pacific circulation responsible for ENSO) have been in place since about 3 to 2.5 Ma (Bowman et al., 
2010). This suggests many ecosystems in northern Australia have experienced monsoonal conditions 
for many millions of years. However, past climates have been both wetter and drier than the 
instrumental record for northern Australia, and the influence of ENSO has varied considerably over 
recent geological time. Several authors have found that present levels of tropical cyclone activity (i.e. 
over the instrumental record) in northern Australia are low (Denniston et al., 2015; Forsyth et al., 
2010; Nott and Jagger, 2013) and possibly unprecedented over the past 550 to 1500 years (Haig et 
al., 2014). Furthermore, the recurrence frequencies of high-intensity tropical cyclones (Category 4 to 
Category 5 events) may have been an order of magnitude higher than that inferred from the current 
short instrumental records. 

2.4.5 Changes in rainfall and evaporation under a future climate 







The effects of projected climate change on rainfall and PE are presented in Figure 2-22, Figure 2-23 
and Figure 2-24. This analysis used 32 global climate models (GCMs) to represent a world where the 
global mean surface air temperatures are 1.6 °C higher than approximate 1990 global temperatures. 
This emission scenario is referred to as SSP2-4.5 (IPCC, 2022) and in this report as Scenario C. 
SSP2-4.5 is the most likely future climate scenario according to Hausfather and Peters (2020). 
Because the scale of GCM outputs is too coarse for use in catchment- and point-scale hydrological 
and agricultural computer models, they were transformed to catchment-scale variables using a 
simple scaling technique (PS, pattern scaled) and are referred to as GCM-PSs. See the companion 
technical report on climate (McJannet et al., 2023) for further details. 
In Figure 2-22 the rainfall and PE projections of the 32 GCM-PSs are spatially averaged across the 
Southern Gulf catchments, and the GCM-PSs are ranked in order of increasing mean annual rainfall. 
This figure shows that three (10%) of the projections for GCM-PSs indicate an increase in mean 
annual rainfall by more than 5%, seven (22%) of the projections indicate a decrease in mean annual 
rainfall by more than 5%, and about two-thirds of the projections indicate a change in future mean 
annual rainfall of less than 5% under a 1.6 °C warming scenario. Hence, it can be argued that, based 
on the selected 32 GCM-PSs, the consensus result is that mean annual rainfall in the Southern Gulf 
catchments is not likely to change significantly under Scenario C. 
The spatial distribution of mean annual rainfall under Scenario C is shown in Figure 2-23. In this 
figure, only the third-wettest GCM-PS (i.e. 10% exceedance or Scenario Cwet), the middle (or 
11th-wettest) GCM-PS (i.e. Scenario Cmid), and the third-driest GCM-PS (i.e. 90% exceedance or 
Scenario Cdry) are shown. 
Figure 2-24a shows mean monthly rainfall under scenarios A and C. The data suggest that mean 
monthly rainfall under Scenario Cmid will be similar to mean monthly rainfall under Scenario A. 
Under scenarios Cwet, Cmid and Cdry, the seasonality of rainfall in northern Australia is similar to 
that under Scenario A. 




Change in rainfall and evaporation, graph
\\fs1-cbr\{lw-rowra}\work\1_Climate\4_S_Gulf\2_Reporting\plots\future_climate\mean.annual.percentage.change.per.degree.SSP245.png
For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
Figure 2-22 Percentage change in rainfall and potential evaporation per degree of global warming for the 32 Scenario C 
simulations relative to Scenario A values for the Southern Gulf catchments 

GCM-PS ranked by increasing rainfall for SSP2-4.5. 



Scenario rainfall, map
\\fs1-cbr\{lw-rowra}\work\1_Climate\4_S_Gulf\1_GIS\1_Map_docs\1_Exports\Cl-SG-514-annualRain-Cwet-Cmid-Cdry.png
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-23 Spatial distribution of mean annual rainfall across the Southern Gulf catchments under scenarios (a) Cwet, 
(b)Cmid and (c) Cdry


 

"\\fs1-cbr\{lw-rowra}\work\1_Climate\4_S_Gulf\3_future_climate\summary\ssp245\mean_month_rain_pet.png"
For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
Figure 2-24 (a) Monthly rainfall and (b) potential evaporation for the Southern Gulf catchments under scenarios A and C 

‘C range’ is based on the computation of the 10% and 90% monthly exceedance values, so the lower and upper limits in ‘C 
range’ are not the same as scenarios Cdry and Cwet. Note: the ‘A mean’ line is directly under the ‘Cmid’ line in (a). 

Potential evaporation 

The mean annual change in GCM-PS PE shows projected PE increases of about 2% to 9% 
(Figure 2-22). Under scenarios Cwet, Cmid and Cdry, PE exhibits a similar seasonality to that under 
Scenario A (Figure 2-24b). However, different methods of calculating PE give different results. 
Consequently, there is considerable uncertainty as to how PE may change under a warmer climate. 
See Petheram et al. (2012) and Petheram and Yang (2013) for more detailed discussions. 

Sea-level rise and sea-surface temperature projections 

Global mean sea levels have risen at a rate of 1.7 ± 0.2 mm/year between 1900 and 2010, a rate in 
the order of ten times faster than the preceding century. Australian tide gauge trends are similar to 
the global trends (CSIRO and Bureau of Meteorology, 2015). Sea-level projections for the Southern 
Gulf catchments are summarised in Table 2-3. This information may be considered in coastal 
aquaculture developments and flood inundation of coastal areas. 

Table 2-3 Projected sea-level rise for the coast of the Southern Gulf catchments 

Values are the median of Coupled Model Intercomparison Project (CMIP) Phase 5 global climate models (GCMs). Numbers 
in parentheses are the 5% to 95% range of the same. Projected sea-level rise values are relative to a mean calculated 
between 1986 and 2005. 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
RCP = Representative Concentration Pathway 
Source: CoastAdapt (2017) 

 


Sea-surface temperature increases around Australia are projected with very high confidence for all 
emissions scenarios, which show warming of around 0.4 to 1.0 °C in 2030 under Representative 
Concentration Pathway (RCP) 4.5, and 2 to 4 °C in 2090 under RCP 8.5, relative to a 1986 to 2005 
baseline (CSIRO and Bureau of Meteorology, 2015). There will be regional differences in sea-surface 
temperature warming due to local hydrodynamic responses; however, there is only medium 
confidence in coastal projections as climate models do not resolve local processes (CSIRO and Bureau 
of Meteorology, 2015). For the Southern Gulf catchments, the corresponding projected sea-surface 
temperature increases are 0.7 °C (range across climate models is 0.5 to 1.0 °C) in 2030 under RCP 4.5 
and 2.9 °C (2.4 to 3.9 °C) in 2090 under RCP 8.5. These changes are relative to a 1986 to 2005 
baseline (CSIRO and Bureau of Meteorology, 2015). Note that the data in Table 2-3 use the CMIP5 
dataset to provide estimates of sea-level rise. An updated product that uses CMIP6 was not available 
at the time of writing. 

2.4.6 Establishment of an appropriate hydroclimate baseline 

The allocation of water and the design and planning of water resources infrastructure and systems 
require great care and consideration and need to be based on scientific evidence and take a genuine 
long-term view. A hydroclimate baseline from 1890 to 2022 (i.e. current) was deemed the most 
suitable baseline for the Assessment. 

A poorly considered design can result in an unsustainable system or preclude the development of a 
more suitable and possibly larger system, thus adversely affecting existing and future users, 
industries and the environment. Once water is overallocated, it is economically, financially, socially 
and politically difficult to reduce allocations in the future, unless water allocations are only assigned 
over short time frames (e.g. <15 years) and then reassessed. However, many water resource 
investments, particularly agricultural investments, require time frames longer than 30 years as there 
are often large initial infrastructure costs and a long learning period before full production potential 
is realised. Consequently, investors require certainty that, over their investment time frame (and 
potentially beyond), their access to water will remain at the level of reliability initially allocated. A key 
consideration in developing a water resource plan, or in assessing the water resources of a 
catchment, is the time period over which the water resources will be analysed, also referred to as the 
hydroclimate ‘baseline’ (e.g. Chiew et al., 2009). 

If the hydroclimate baseline is too short, it can introduce biases in a water resource assessment for 
various reasons. First, the transformation of rainfall to runoff and rainfall to groundwater recharge is 
non-linear. For example, averaged across the catchment of the Flinders River in northern Australia, 
the mean annual rainfall is only 8% higher than the median annual rainfall, yet the mean annual 
runoff is 59% higher than the median annual runoff (Lerat et al., 2013). Similarly, the median annual 
rainfall between 1895 and 1945 was the same as the median annual rainfall between 1948 and 1987 
(less than 0.5% difference), yet there was a 21% difference in the median annual runoff between 
these two time periods (and a 40% difference in the mean annual runoff) (Lerat et al., 2013). 
Consequently, great care is required if using rainfall data alone to justify the use of short periods over 
which to analyse the water resources of a catchment. 

In developing a water resource plan, the volume of water allocated for consumptive purposes is 
usually constrained by the drier years (referred to as dry spells when consecutive dry years occur) in 
the historical record (see Section 2.4.4). This is because it is usually during dry spells that water 


extraction most adversely affects existing industries and the environment. All other factors (e.g. 
market demand, interest rates) being equal, consecutive dry years are usually also the most limiting 
time periods for new water resource developments and/or investments, such as irrigated agricultural 
enterprises, particularly if the dry spells coincide with the start of an investment cycle. Consequently, 
it is important to ensure a representative range of dry spells (i.e. of different durations, magnitudes 
and sequencing) are captured over the Assessment time period. For example, two time periods may 
have very similar median annual runoffs, but the duration, magnitude and sequencing of the dry 
spells may be sufficiently different that they pose different risks to investors and result in different 
modelled ecological outcomes. 

In those instances where there is the potential for a long memory, such as in intermediate- and 
regional-scale groundwater systems or in river systems with large reservoirs, long periods of record 
are preferable to minimise the influence of initial starting conditions (e.g. assumptions regarding 
initial reservoir storage volume), to properly assess the reliability of water supply from large storages 
and to encapsulate the range of likely conditions (McMahon and Adeloye, 2005). 

All these arguments favour using as long a time period as practically possible. However, in some 
circumstances a shorter period may be preferable on the basis that it is a more conservative option. 
For example, in south-western Australia, water resource assessments to support water resource 
planning are typically assessed from 1975 onwards (Chiew et al., 2012; McFarlane et al., 2012). This is 
because there has been a marked reduction in runoff in south-western Australia since the mid-1970s, 
and this declining trend in rainfall is consistent with the majority of GCM projections, which project 
reductions of rainfall into the future (McJannet et al., 2023). 

Although there were few rainfall stations in the study area at the turn of the 20th century relative to 
2019 (McJannet et al., 2023), an exploratory analysis of rainfall statistics of the early period of the 
instrumental record does not appear to be anomalous when compared to the longer-term 
instrumental record. 

In deciding upon an appropriate time period over which to analyse the water resources of the 
Southern Gulf catchments, consideration was given to the above arguments, as well as to 
palaeoclimate records, observed trends in the historical instrumental rainfall data and future climate 
projections. 

For the Southern Gulf catchments, although there is evidence of an increasing trend in rainfall in the 
recent instrumental record, two-thirds of the GCM-PSs project no change in mean annual rainfall for 
a 1.6 °C warming scenario. Furthermore, palaeoclimate records indicate multiple wetter and drier 
periods have occurred in the recent geological past (Northern Australia Water Resource Assessment 
technical report on climate (Charles et al., 2017)). Very few climate data are available in the Southern 
Gulf catchments before 1890, so the baseline adopted for this Assessment was 1890 to 2022. 

Note, however, that as climate is changing on a variety of timescales, detailed scenario modelling and 
planning (e.g. the design of major water infrastructure) should be broader than just comparing a 
single hydroclimate baseline to an alternative future. 


2.5 Hydrology of the Southern Gulf catchments 

2.5.1 Introduction 

The timing and event-driven nature of rainfall events and high PE rates across the Southern Gulf 
catchments have important consequences for the catchments’ hydrology. The spatial and temporal 
patterns of rainfall and PE across the Southern Gulf catchments are discussed in Section 2.4. Rainfall 
can be broadly broken into evaporated and non-evaporated components (the latter is also referred 
to as ‘excess water’). The non-evaporated component can be broadly broken into overland flow and 
recharge (Figure 2-25). Recharge replenishes groundwater systems, which in turn discharge into 
rivers and the ocean. Overland flow and groundwater discharged into rivers combine to become 
streamflow. Streamflow in the Assessment is defined as a volume per unit of time. Runoff is defined 
as the millimetre depth equivalent of streamflow. Flooding is a phenomenon that occurs when the 
flow in a river exceeds the river channel’s capacity to carry the water, resulting in water spilling onto 
the land adjacent to the river. 



Water balance, diagram
\\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\10_Reporting\1_All\9_Graphics_artist\2_SoG\C Petheram Southern Gulf 1_7_2024 Waterbalance Chpter 2.jpg
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-25 Simplified schematic diagram of terrestrial water balance in the Southern Gulf catchments 

Runoff is the millimetre depth equivalent of streamflow. Overland flow includes shallow subsurface flow. Numbers 
indicate mean annual values spatially averaged across the catchment under Scenario A. Numbers will vary locally. 

Section 2.5 covers the remaining terms of the terrestrial water balance (accounting for water inputs 
and outputs) of the Southern Gulf catchments, with particular reference to the processes and terms 
relevant to irrigation at the catchment scale. Information is provided on groundwater, groundwater 
recharge and surface water – groundwater connectivity. Runoff, streamflow, flooding and persistent 
waterholes in the Southern Gulf catchments are then discussed. 

Figure 2-25 shows a schematic diagram of the water balance of the Southern Gulf catchments, along 
with estimates of the mean annual value spatially averaged across the catchment and an estimate of 


the uncertainty for each term. The ‘water balance’ comprises all the water inflows and outflows to 
and from a particular catchment over a given time period. 

Unless stated otherwise, the material in sections 2.5.2 to 2.5.4 is based on findings described in the 
companion technical report on hydrogeological assessment (Raiber et al., 2024). Similarly, the 
material in Section 2.5.5 draws on the findings of the companion technical report on river modelling 
(Gibbs et al., 2024), unless stated otherwise. 

2.5.2 Groundwater 

Within the Southern Gulf catchments, the distribution, availability and quality of groundwater 
resources are heavily influenced by the physical characteristics of the sediments and rocks of the 
major geological divisions (see Section 2.2). Aquifers are the rocks and sediments in the subsurface 
that store and transmit groundwater. 

The catchments have several types of aquifer: 

• fractured and weathered rocks associated with Proterozoic basins (associated with the Proterozoic 
McArthur and South Nicholson basins and Isa Superbasin) (mostly covered by younger strata) 
• fractured, fissured and karstic carbonate rocks of the Georgina Basin (Cambrian limestone and 
Cambrian dolostone in Figure 2-26) 
• extensive porous sedimentary sandstones of the Great Artesian Basin (not present at the surface in 
the Southern Gulf catchments; for extent, see Figure 2-4 and Figure 2-31) 
• porous sandstones of the Karumba Basin (Cenozoic sediments, Figure 2-4) 
• surficial unconsolidated to consolidated alluvial sands and gravels (Cenozoic alluvium in Figure 
2-26). 


The sedimentary limestones of the Georgina Basin – in particular, the Camooweal Dolostone and 
Thorntonia Limestone – and the aquifers of the Carpentaria Sub-basin of the GAB host the largest, 
most regionally extensive groundwater resource in the Southern Gulf catchments. 

The upper fractured, fissured and karstic parts of the Cambrian carbonate rocks of the Georgina Basin 
(Figure 2-4 and Figure 2-31) in the Southern Gulf catchments may be regionally connected to the 
limestones of the adjacent Daly and Wiso basins, which combined are often referred to as the 
Cambrian Limestone Aquifer. The Cambrian Limestone Aquifer extends for several hundred thousand 
square kilometres to the north, west and south of the Southern Gulf catchments. It hosts limestones 
that form a complex, interconnected and highly productive regional-scale groundwater system. That 
is, the distance between the recharge areas (where there is inflow of water through the soil, past the 
root zone and into an aquifer) and discharge areas (where there is outflow of water from an aquifer 
into a water body or as evaporation from the soil or vegetation) can be tens of kilometres to 
hundreds of kilometres, and the time taken for groundwater to discharge following recharge can be 
in the order of thousands to hundreds of thousands of years. 




Simplified regional hydrogeology map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\11_Groundwater\4_S_Gulf\1_GIS\1_Map_docs\Gr-S-515_simplified_regional_hydrogeology_CR.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-26 Simplified regional hydrogeology of the Southern Gulf catchments 

This map does not represent outcropping areas of all hydrogeological units: the blanket of surficial Cretaceous to 
Quaternary regolith sediments has been removed to highlight the spatial extent of various regional hydrogeological units 
in the subsurface. 

Geology data sources adapted from: Department of Industry, Tourism and Trade (2014) and Department of Environment, Parks and Water Security 
(2008) and Raymond et al. (2012) 
Spring data sources: Department of Environment, Parks and Water Security (2013); the Groundwater Dependent Ecosystems Atlas (Bureau of 
Meteorology, 2017) and Queensland Government (2021) 


The porous sandstones of the geological Carpentaria Basin (Figure 2-4) – in particular the Gilbert 
River Formation (GRF) and to a lesser extent the Normanton Formation – host the most regionally 
extensive aquifer systems within the Southern Gulf catchments. They extend over the eastern part of 
the catchment in Queensland and are entirely covered by the Cenozoic Karumba Basin. The aquifers 
of the geological Carpentaria Basin form part of the 1.7 million km2 large GAB that reaches very far to 
the south and east of the Southern Gulf catchments (Figure 2-31) and also includes the Eromanga 
and Surat basins and parts of the Clarence–Moreton Basin. Within the Southern Gulf catchments, the 
geological Carpentaria Basin is entirely covered by the Cenozoic Karumba Basin. Recharge and 
discharge processes within the geological Carpentaria Basin are relatively poorly characterised due to 
the relatively limited number of groundwater monitoring bores. The near-absence of environmental 
tracer data in the geological Carpentaria Basin was identified as a key data gap within the GAB in a 
recent GAB-wide environmental tracer study (Raiber et al., 2022). 

Other more local- to intermediate-scale aquifer systems may exist in other geological formations 
within the Southern Gulf catchments. Previous studies described the Proterozoic rocks trending 
north-west to south-east across the central part of the Southern Gulf catchments (Figure 2-2) as not a 
feasible groundwater resource. However, other studies suggested that the Mount Isa town water 
supply was sourced from fractured shales until the construction of the Lake Moondarra dam. These 
shales occur at depths of 60 to 80 metres below ground level (mBGL), and bores yielded 5 to 
10 L/second. In addition, approximately 50% of the bores with stratigraphic information in the 
Southern Gulf catchments correspond to Proterozoic units composed of unassigned granites or are 
attributed to one of the geological units of the South Nicholson Basin and Isa Superbasin. 
Furthermore, the variability of groundwater chemistry found among the Proterozoic aquifers, with 
dominant ions varying from magnesium, calcium and bicarbonate (Mg–Ca–HCO3) to sodium and 
sulfate (Na–SO4), may be an indication of localised recharge and interactions of groundwater with 
variable mineral-rich rocks. 

The surficial fluvial and, to a lesser extent, shallow-shelf marine Cenozoic sediments of the Karumba 
Basin and younger alluvial aquifer systems in the Southern Gulf catchments may form local- to 
intermediate-scale aquifer systems. The basal Bulimba Formation has been described as the most 
productive aquifer of the Karumba Basin. Its lithological properties have been described as highly 
variable, from shale to sandy ferricrete, resulting in variable hydraulic properties and groundwater 
yields. Generally, the sedimentary sequences of the Karumba Basin and younger alluvial aquifer 
systems within the Southern Gulf catchments remain poorly characterised. 

Hydrogeological units 

Hydrogeological units of the Southern Gulf catchments are shown in Figure 2-26. The rocks and 
sediments of these geological units host a diverse range of aquifers that vary in extent, storage and 
productivity. The major and most extensive aquifers in the Southern Gulf catchments are found in the 
Cambrian limestone of the Georgina Basin and the sandstones of the Jurassic to Cretaceous 
Carpentaria Sub-basin of the GAB. For this Assessment, major aquifer systems are defined as aquifers 
that contain regional and intermediate-scale groundwater systems with adequate storage volumes 
(i.e. gigalitres) that could potentially yield water at a sufficient rate (>10 L/second) and be of a 
sufficient water quality (<1000 mg/L total dissolved solids (TDS)) for a range of irrigated cropping. 
Minor aquifers are defined as aquifers that contain local-scale groundwater systems with lower 
storage (i.e. megalitres) (Figure 2-27). The yields from minor aquifers are variable and often low 


(<5 L/second), and minor aquifers have variable water quality ranging from fresh (~500 mg/L TDS) to 
brackish (~3000 mg/L TDS). The distribution and characteristics of these rocks is covered in Section 

Unless otherwise stated, the material in Section 2.5.2 is based on findings described in the 
companion technical report on hydrogeological assessment by Raiber et al. (2024). Only the major 
aquifers relevant to potential opportunities for future groundwater resource development are 
discussed in detail. 



For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
Figure 2-27 Two-dimensional conceptual schematic of the interconnected aquifer system and its variability 

Bore yields vary significantly depending on where (which geological unit) a bore is installed and at what depth. 

Adapted from DENR (2016) 

Cambrian limestone aquifers 

The Cambrian limestone aquifers of the Georgina Basin occur in the western part of the Southern 
Gulf catchments (Figure 2-26). 

Due to the limited number of groundwater bores within the Southern Gulf catchments, data from 
groundwater bores outside the boundary of the catchment were also used to provide a more robust 
overview of the hydrogeological properties of the different formations. 

Camooweal Dolostone and Thorntonia Limestone – Georgina Basin 

Based on existing hydrogeological data, the fractured and karstic carbonated rocks hosted in the 
Georgina Basin also offer potential to support productive bores (i.e. yields greater than 10 L/s), but 
they remain poorly characterised. The Camooweal Dolostone, which occurs in the south-west of the 
catchments (Cambrian dolostone in Figure 2-26), is mostly composed of dolostone and dolomitic 


limestone (Geoscience Australia and Australian Stratigraphy Commission, 2021; Matthews, 1992). It 
is the shallowest of the Georgina Basin’s more prospective hydrogeological units in the Southern Gulf 
catchments and has an approximate spatial outcrop extent of approximately 2972 km2 within the 
Southern Gulf catchments. At a new stratigraphic well (Carrara 1) drilled as part of the National 
Drilling Initiative within the Southern Gulf catchments, the thickness of the Camooweal Dolostone is 
more than 200 m. 

The Thorntonia Limestone occurs in the south-west of the Southern Gulf catchments (Cambrian 
limestone in Figure 2-26) and is composed mostly of dolostone and dolomitic limestone (Geoscience 
Australia and Australian Stratigraphy Commission, 2021). It is overlain by the Camooweal Dolostone 
and is confined in parts by the Wonarah Formation. The limestone aquifers occur mostly in the NT, 
but also outcrop and subcrop in far western Queensland, and host a significant regional groundwater 
system (Figure 2-26). The Thorntonia Limestone has an outcropping zone of approximately 2515 km2 
within the Southern Gulf catchments and is up to approximately 100 m thick (CSIRO, 2009b; Taylor et 
al., 2021). 



For more information on this figure please contact CSIRO on enquiries@csiro.au






Figure 2-28 Gregory River at Riversleigh Road 
Photo: CSIRO – Russell Crosbie 
The median depth of groundwater bores screened within the Cambrian limestones (Camooweal 
Dolostone and Thorntonia Limestone, undifferentiated) in the Southern Gulf catchments is 101 m 
(with a range from 24 to 537 m). 
Groundwater within these formations is mostly fresh to brackish with a median salinity of 
approximately 1300 mg/L TDS (ranging from <100 to approximately 6,000 mg/L TDS). The ionic 
composition of groundwater within the Cambrian limestones is variable, with a predominance of 
calcium, magnesium and bicarbonate (Ca–Mg–HCO3) or sodium, bicarbonate and chloride (Na–HCO3–Cl






For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-29 Lawn Hill Gorge 

Photo: CSIRO – Russell Crosbie 

Wonarah Formation – Georgina Basin 

The Wonarah Formation of the Georgina Basin occurs in the south-west portion of the Southern Gulf 
catchments (Cambrian siltstone in Figure 2-26) and merges laterally into the Anthony Lagoon 
Formation (the Wiso Basin stratigraphic equivalent) (Tickell and Bruwer, 2017). The Wonarah 
Formation is predominantly composed of silty dolostone with interbedded (minor) dolomitic and 
calcareous mudstone and siliciclastic mudstone. It has a maximum thickness of 244 m in holes drilled 
in its equivalent Anthony Lagoon Formation (Kruse and Dunster, 2013). Very little information exists 
for the Wonarah Formation in the Southern Gulf catchments. It therefore remains unclear if it 
exhibits the same characteristics as the Anthony Lagoon Formation in the Wiso Basin much further to 
the west in the NT. These formations are fractured, highly heterogeneous and partially karstic, with 
estimated transmissivities of 13 to 8200 m2/day (Kruse and Dunster, 2013). Indicative 
hydrogeological data and anecdotal evidence for aquifers in the Wonarah Formation and equivalent 


come from Tickell (2003). Tickell (2003) described the hydrogeological unit in the Barkly Tableland as 
fractured and cavernous rocks assigned to both the Georgina and Wiso basins. Aquifers range in 
depth from 50 to 125 mBGL, and standing water levels vary from 30 to 100 mBGL. Indicative bore 
yield data based on airlifting at the time of drilling varied from 0.5 to 5 L/second. However, mud 
circulation losses during drilling were commonly reported, suggesting the presence of cavernous 
limestones and potential for high-yielding aquifers. Groundwater quality was also described as fresh 
to brackish (500 to 1500 mg/L TDS) across most of the area investigated (Tickell, 2003). 

Gilbert River Formation – Carpentaria Sub-basin of the Great Artesian Basin 

The Gilbert River Formation (GRF), or Gilbert River Aquifer (GRA), is the major aquifer within the 
Jurassic to Cretaceous sedimentary rocks of the geological Carpentaria Basin in the north-east of the 
catchments (Figure 2-31). The extensive sandstone aquifers are intersected by bores ranging in depth 
from approximately 100 to 750 mBGL. The GRF in the Southern Gulf catchments and adjacent areas 
has significant potential as an aquifer for groundwater-based irrigation. Hydraulic conductivity values 
for the GRF in the northern geological Carpentaria Basin range from 0.1 to 10 m/day, and 
transmissivities range from 4 to 570 m2/day (Horn et al., 1995; Klohn Crippen Berger, 2016). Reported 
bore yields range from less than 0.5 L/second up to 46 L/second (Figure 2-32). It is anticipated that 
yields would likely exceed 10 L/second with appropriately constructed large-diameter production 
bores. The GRF is confined by the thick and laterally continuous aquitard of the Rolling Downs Group. 
In some places this results in artesian conditions as, for example, reported for a bore in Burketown. 
Groundwater salinity in the GRF ranges from fresh (<500 mg/L TDS) to brackish (>3000 mg/L TDS) 
with a median TDS of 500 mg/L (Figure 2-33), which is still suitable for irrigation use. The ionic 
composition of the groundwater of the GRF is dominated by Na–HCO3–Cl and Na–Cl–HCO3, which is 
indicative of mature groundwaters evolved along very long flow paths. Low calcium and magnesium 
and high concentrations of fluoride have also been observed. An assessment of recharge processes 
and flow dynamics in the GAB by Raiber et al. (2022) identified the lack of environmental tracer data 
in the geological Carpentaria Basin as a key data gap within the GAB. 




Figure 2-30 The Gregory River receives groundwater discharge from the Cambrian Limestone Aquifer 

Photo: CSIRO – Nathan Dyer 




Full extent of Basins and GAB, map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-31 Full extent of the Georgina Basin and Carpentaria Sub-basin of the Great Artesian Basin. Inset map shows 
full extent of Great Artesian Basin 

Geology data sources adapted from: Department of Industry, Tourism and Trade (2014) and Department of Environment, Parks and Water Security 
(2008) and Raymond et al. (2012) 




 

Major aquifer bore yield, map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-32 Groundwater bore yields for major aquifers across the Southern Gulf catchments 

Symbol shapes indicate the aquifer within which the bore is sited; colours indicate bore yield class. 

Bore yield data source: Department of Environment, Parks and Water Security (2014); DNRME (2023) 

 




Major aquifer groundwater salinity, map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-33 Groundwater salinity for major aquifers in the Southern Gulf catchments 

Symbol shapes indicate the aquifer within which the bore is sited; colours indicate total dissolved solids (TDS). 

Salinity data source: Department of Environment, Parks and Water Security (2014); DNRME (2023) 




Bulimba Formation and alluvial aquifer systems 

Consisting of lacustrine, fluvial and, to a lesser extent, shallow-shelf marine sediments, the 
widespread Cenozoic sediments of the Karumba Basin unconformably overlie the Carpentaria Sub-
basin of the GAB (Bradshaw et al., 2009). Within the Southern Gulf catchments, Cenozoic sediments 
are expected to reach a maximum thickness of 40 m (north of Doomadgee). The most productive 
aquifer is expected to correspond to the basal section of the Bulimba Formation, which is mostly 
composed of fine-grained quartzose sediments (Herbert, 2000; Radke et al., 2012). Lithological 
properties of the Bulimba Formation are highly variable, from shale to sandy ferricrete, resulting in 
variable hydraulic properties and groundwater yields (i.e. 0.25 to 4.5 L/second) (DNRME, 2021). 
Nevertheless, at the central area of Nicholson catchment, where the alluvial deposits are wider 
(downstream of Doomadgee) (Figure 2-26), the Bulimba Formation is the most accessed aquifer from 
the Karumba Basin (Buchanan et al., 2020). Its hydraulic conductivity ranges from 150 to 300 m/day 
with specific yield of 0.1 (Smerdon et al., 2012). 

The Cenozoic alluvial aquifers in the middle to lower reaches of the Nicholson, Gregory and 
Leichhardt rivers, and Settlement Creek and its tributaries, host local-scale groundwater systems. 
However, data are very sparse, and these water resources remain poorly understood. The median 
TDS of shallow alluvial groundwaters in the Southern Gulf catchments is approximately 600 mg/L, and 
the reported yields are relatively low (median of 2 L/second). However, this is based on very few data 
points, and additional data on the extent, thickness, internal architecture and hydraulic properties of 
alluvial aquifers are required to assess their suitability as productive and reliable water supplies. 

Fractured rock aquifers 

CSIRO (2009c) described the Proterozoic rocks trending north-west to south-east across the central 
part of the Southern Gulf catchments (Figure 2-2) as not a feasible groundwater resource. However, 
McEniery (1980) pointed out that the Mount Isa town water supply was sourced from fractured 
shales until the construction of the Lake Moondarra dam. These shales occur at depths of 60 to 
80 mBGL and yield from 5 to 10 L/second. Approximately 50% of the bores with stratigraphic 
information in the Southern Gulf catchments correspond to Proterozoic units composed of 
unassigned granites or are attributed to one of the following geological units: Lawn Hill, Corella, 
Paradise Creek, Surprise Creek, Toole Creek Volcanics, Lady Loretta and Gunpowder Creek. These 
geological units are considered to potentially host local-scale fractured and weathered rock aquifers 
(Raiber et al., 2024). According to the data compiled by Bardwell and Grey (2016), a significant spatial 
variability in groundwater chemistry is found among the Proterozoic aquifers, with dominant ions 
varying from Mg–Ca–HCO3 to Na–SO4. Such characteristics may be an indication of localised 
recharge and interactions of groundwater with variable mineral-rich rocks. 

2.5.3 Groundwater recharge 

Groundwater recharge is an important component of the water balance of an aquifer. It can inform 
how much an aquifer is replenished on an annual basis and therefore how sustainable a groundwater 
resource may be in the long term. This is particularly important for aquifers with low storage or 
aquifers that discharge to rivers, streams, lakes and the ocean or via transpiration from groundwater-
dependent vegetation. Recharge is influenced to varying degrees by many factors, including spatial 
changes in soil type (and their physical properties), the amount of rainfall and evaporation, 


vegetation type (and transpiration), topography and depth to the watertable. Recharge can also be 
influenced by changes in land use, such as land clearing and irrigation. Directly measuring recharge 
can be very difficult as it usually represents only a small component of the water balance, can be 
highly variable spatially and temporally, and can vary depending on the type of measurement or 
estimate technique used (Petheram et al., 2002). 

In the Assessment, several independent approaches were used to estimate annual recharge for all 
aquifers in the Southern Gulf catchments. Figure 2-34 provides an example of recharge estimates 
using the upscaled chloride mass balance (CMB) method. 

For more detail on how these estimates were derived, see the companion technical report on 
hydrogeological assessment (Raiber et al., 2024). 



Annual recharge, map
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Figure 2-34 Annual recharge estimates for the Southern Gulf catchments 

Estimates based on upscaled chloride mass balance (CMB) method for the (a) 50th, (b) 5th and (c) 95th percentiles. 

Figure 2-35 provides a summary of the range in recharge estimates for the outcropping area of seven 
key hydrogeological units across the Southern Gulf catchments (Figure 2-26). Recharge estimates are 
based on the mean of the 5th and 95th percentiles and range from approximately: 

•3 to 28 mm/year for the Camooweal Dolostone
•14 to 46 mm/year for the Cretaceous sediments
•14 to 55 mm/year for the fractured rocks



• 22 to 89 mm/year for the Proterozoic carbonates 
• 3 to 30 mm/year for the Thorntonia Limestone (or equivalent) 
• 3 to 20 mm/year for the Wonarah Formation 
• 9 to 29 mm/year for the alluvium. 


The estimates of groundwater recharge in the Assessment represent the spatial variability in 
recharge across the land surface and are a good starting point for estimating a water balance 
arithmetically or using a groundwater model. However, none of the methods accounts for aquifer 
storage (available space in the aquifer), so it is unclear whether the aquifers can accept these rates of 
recharge on an annual basis. The methods also do not account for potential preferential recharge 
from streamflow or overbank flooding or through karst features across parts of the Southern Gulf 
catchments. Therefore, the key features of an aquifer must be carefully conceptualised before simply 
deriving a recharge volume based on the surface area of an aquifer outcrop and an estimated 
recharge rate. 

 

For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-35 Summary of recharge statistics to outcropping areas of key hydrogeological units across the Southern Gulf 
catchments 

Recharge rates are based on upscaled chloride mass balance (CMB) method and calculated as the mean of the 5th and 
95th percentiles. Error bars represent the standard deviation from the mean. 

2.5.4 Surface water – groundwater connectivity 

As discussed in Section 2.5.2, groundwater discharge to surface water features occurs from a variety 
of aquifers across the Southern Gulf catchments. Areas of groundwater discharge are important for 
sustaining both aquatic and terrestrial groundwater-dependent ecosystems and often have cultural 
significance. These groundwater discharge areas have been mapped in Figure 2-36 as three 
categories: perennial, seasonally varying and coastal. Perennial groundwater discharge areas often 
exhibit springs that occur in a variety of hydrogeological settings; these can involve groundwater flow 
systems at a variety of scales ranging from hundreds of metres to a few hundred kilometres. Areas of 


seasonally varying groundwater discharge generally exhibit localised alluvial and fractured and 
weathered rock aquifer systems, and surface water recharges waterholes and alluvial and fractured 
rock aquifers adjacent to streams during the wet season. These stores of water may sustain the 
riparian vegetation through the dry season. Although surface water is thought to be the major source 
for these systems, groundwater discharge from adjacent aquifers can also occur when river levels 
recede during the dry season. Coastal discharge areas may have a component of coastal submarine 
groundwater discharge but also have mangroves that use fresh to saline water within the 
freshwater–saltwater interface. 

Groundwater discharge at spring vents connected to stream channels likely occurs in some parts of 
the Southern Gulf catchments. For example, permanently saturated springs of the Boodjamulla spring 
complex (Figure 2-36) are mapped along Lawn Hill Creek in the headwaters of the Nicholson River. 
The occurrence of springs in this area has been linked to groundwater discharge from underlying 
Proterozoic sedimentary rock aquifers (Buchanan et al., 2020). The drivers of potential groundwater 
discharge from deeper units in this area are not currently well understood due to a lack of 
hydrochemistry and environmental tracer data. However, multiple possible mechanisms have been 
described. This includes, for example, groundwater discharge driven by gas overpressure from the 
shale-rich sequences in the Isa Superbasin. Surface faults and regional structural features occur near 
the springs, and the location of these springs also corresponds with a distinct change in elevation of 
approximately 100 m from west to east, which could indicate groundwater discharge at a break in 
slope (Buchanan et al., 2020). 

A recent assessment by Geoscience Australia (Dixon-Jain et al., 2024) used geological and historical 
and newly acquired geophysical (seismic and airborne electromagnetic) data to study the influence of 
geological structures on the occurrence of groundwater-dependent ecosystems. The study indicated 
that some of the springs north of Lawn Hill Creek of the Boodjamulla spring complex (Figure 2-36) 
appear to be associated with the Constance Sandstone, which is part of the South Nicholson Basin, 
with faults and fractures potentially forming pathways for groundwater discharge. The study also 
highlighted that other potential spring-source aquifers may exist, including a possible indirect 
groundwater source originating from the Thorntonia Limestone (part of the Georgina Basin) and 
flowing into the Constance Sandstone (with alternative hydrogeological conceptualisations discussed 
in more detail in the companion hydrogeological technical report by Raiber et al., 2024). 

Other mapped, permanently active springs in the south-western part of the Southern Gulf 
catchments in the headwaters of the Gregory River (Figure 2-28) are spatially associated with and 
likely drain the Thorntonia Limestone. Dixon-Jain et al. (2024) highlighted that further hydrochemical 
sampling, including environmental tracers, is required to understand the hydrogeology of the springs 
within the Southern Gulf catchments. 

Shallow groundwater from the Karumba Basin sediments likely supports terrestrial and aquatic 
groundwater-dependent ecosystems on the alluvial floodplains. 


 

Groundwater discharge, map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-36 Spatial distribution of groundwater discharge classes including surface water – groundwater connectivity 
across the Southern Gulf catchments 

Groundwater discharge classes are inferred from remotely sensed estimates of evapotranspiration and open water 
persistence (based on findings described in the companion technical report on hydrogeological assessment by Raiber et 
al., 2024). Note: the size of polygons has been greatly exaggerated to allow them to be seen at this scale. 

Geology data sources: adapted from Department of Industry, Tourism and Trade (2014) and Department of Environment, Parks and Water Security 
(2008) and Raymond et al. (2012) 
Spring data sources: Department of Environment, Parks and Water Security (2013); the Groundwater Dependent Ecosystems Atlas (Bureau of 
Meteorology, 2017) and Queensland Government (2021) 


2.5.5 Surface water 

Streamflow 

Approximately 60% of Australia’s runoff is generated in northern Australia (Petheram et al., 2010, 
2014). Unlike the large internally draining Murray–Darling Basin, however, northern Australia’s runoff 
is distributed across many hundreds of smaller externally draining catchments (Figure 2-37). To place 
the Southern Gulf catchments in a broader context, it is useful to compare its size and the magnitude 
of its median annual streamflow to other river systems across Australia. Figure 2-37 shows the 
magnitude of median annual streamflow of major rivers across Australia prior to water resource 
development. 

 

Streamflow Australia, map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-37 Modelled streamflow under natural conditions 

Streamflow under natural conditions is indicative of median annual streamflow prior to European settlement (i.e. without 
any large-scale water resource development or extractions) assuming the historical climate (i.e. 1890 to 2015). 

Source: Petheram et al. (2017) 

The Southern Gulf catchments consist of the contributing area of various rivers and streams that 
discharge into the southern Gulf of Carpentaria. The most substantial of these are the Leichhardt, 
Gregory and Nicholson rivers. The catchments of these rivers, plus those on the Wellesley Islands in 
the Gulf of Carpentaria, Settlement Creek, Morning Inlet, and numerous small coastal creeks, have a 












total area of 108,200 km2. The Leichhardt catchment has an area of 33,400 km2, and the river itself 
extends approximately 550 km from the river mouth to Mount Isa in the south of the catchment. 
Tidal influence on streamflow is detectable approximately 15 km upstream of Burketown on the 
Albert River before the water becomes brackish. On the Leichhardt River, brackish salinity is likely to 
extend as far up as Leichhardt Falls, 113 km from the mouth. The falls are just below station 913007B 
on Leichhardt River at Floraville Station (Figure 2-38), the only operating streamflow station in the 
lower plains in the Southern Gulf catchments. 
The median and mean annual discharges from all Southern Gulf catchments are 4961 and 
6759 GL/year, respectively. The pronounced difference between the mean and median is due to the 
mean being biased by a number of very high flow years (Table 2-4). Current surface water licences 
across the study area total about 114 GL (2.3% of median annual flow). See Section 3.3 for more 
information. 
The cease-to-flow column in Table 2-4 gives the percentage of time that no streamflow was observed 
at each of the streamflow gauging stations in the catchments. Gauges on the Gregory River indicate 
perennial flow, with dry-season baseflow resulting from discharge from the Thorntonia Limestone 
hydrogeological unit. Other rivers ceased to flow for 27% to 79% of the time, driven by the seasonal 
rainfall that has on average 94% of the rainfall falling during the wet season (Section 2.4). The 
influence of storage at Lake Julius results in a higher cease-to-flow period, with spills occurring 13% of 
the time. Lake Julius and Lake Moondarra, two large storages (approximately 107 GL each) in the 
upper Leichhardt River, are used for town and industrial water supply near Mount Isa. There are 
75.1 GL of licences allocated from the storages; however, only a portion of this volume is currently 
used each year (typically ~40%). 
Table 2-4 Streamflow metrics at selected gauging stations in the Southern Gulf catchments 
Annual streamflow data are calculated under Scenario A. The 20th, 50th and 80th refer to 20%, 50% and 80% percentile 
exceedance, respectively. Cease-to-flow percentage (the percentage of all observation days where no streamflow was 
recorded) is determined using observed data, where streamflow less than 0.1 ML/day was assumed to be equal to zero. 
The annual streamflow data are shown schematically in Figure 2-39 and Figure 2-40. 

STATION ID 

STATION NAME 

CATCHMENT 
AREA 

(HA) 

ANNUAL STREAMFLOW 
(GL) 

CEASE- 
TO-FLOW 
% 

RUNOFF 
COEFFICIENT 

MEAN 

80TH 

50TH 

20TH 

913014A 

Leichhardt River at Doughboy Creek 

3,520 

115 

27 

72 

153 

63 

0.07 

913015A 

Leichhardt River at Julius Dam 

4,748 

122 

0 

41 

163 

87 

0.06 

913004A 

Leichhardt River at Miranda Creek 

5,959 

213 

27 

92 

277 

62 

0.08 

913006A 

Gunpowder Creek at Gunpowder 

2,412 

128 

42 

85 

171 

72 

0.11 

913010A 

Fiery Creek at 16 Mile Waterhole 

721 

41 

12 

27 

55 

79 

0.11 

913007B 

Leichhardt River at Floraville Homestead 

23,679 

1157 

308 

693 

1670 

49 

0.10 

912108A 

O Shannassy River at 17.7 Km 

5,591 

238 

103 

179 

334 

0 

0.09 

912105A 

Gregory River at Riversleigh No.2 

11,382 

475 

213 

343 

681 

0 

0.09 

912101A 

Gregory River at Gregory Downs 

12,567 

506 

226 

363 

708 

0 

0.09 

912103A 

Lawn Hill Creek at Lawn Hill No 2 

4,003 

164 

59 

116 

219 

27 

0.09 

912107A 

Nicholson River at Connolly’s Hole 

13,875 

649 

82 

268 

1092 

34 

0.09 

912116A 

Nicholson River at Doomadgee Mission 

15,117 

730 

98 

325 

1186 

32 

0.09 






streamflow gauges
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Figure 2-38 Streamflow observation data availability in the Southern Gulf catchments 

Figure 2-39 shows how median annual streamflow increases towards the coast in the Southern Gulf 
catchment. As an indication of variability, Figure 2-40 shows the 20% and 80% exceedance of annual 
streamflow compared to the median (50% exceedance) in Figure 2-39. 




Streamflow exceedence, map
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For more information on this figure please contact CSIRO on enquiries@csiro.au




Figure 2-39 Median annual streamflow (50% exceedance) in the Southern Gulf catchments under Scenario A 
Commencement threshold for blue flow accumulation line is 5 GL/year. Labelled points refer to Figure 2-49 
Figure 2-41 illustrates the increase in catchment area and decrease in elevation along the 
Gregory–Nicholson River (a) and Leichhardt River (b) from one of the most upstream source 
tributaries to their mouth. The large ‘step’ changes in catchment area are where major tributaries 
join the river. 




Scenario streamflow exceedence
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Figure 2-40 (a) 20% and (b) 80% exceedance of annual streamflow in the Southern Gulf catchments under Scenario A 



For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-41 Catchment area and elevation profile from the upper tributaries in each catchment to the mouth along the 
(a)Gregory–Nicholson River and (b) Leichhardt River


Catchment runoff 

The simulated mean annual runoff averaged over the Southern Gulf catchments under Scenario A is 
76 mm. Figure 2-42 shows the spatial distribution of mean annual rainfall and runoff under Scenario 
A (1890 to 2022) across the study area. Mean annual runoff broadly follows the same spatial patterns 
as mean annual rainfall: highest in the north of the study area and lowest in the south. 

Monthly and annual runoff data in the Southern Gulf catchments exhibit substantial variation from 
one year to the next. The annual runoff volumes at 20%, 50% (median) and 80% exceedance 
averaged across the Southern Gulf catchments are 114, 30 and 10 mm, respectively (Figure 2-43). 
That is, runoff spatially averaged across the catchments will on average exceed 114 mm 1 year in 5, 
30 mm half the time and 10 mm 4 years in 5. Figure 2-43 shows the spatial distribution of annual 
runoff at 20%, 50% and 80% exceedance under Scenario A. 

Intra- and inter-annual variability in runoff 

Rainfall, runoff and streamflow in the Southern Gulf catchments are variable between and within 
years. Approximately 87% of all runoff in the catchments occurs in the 3 months from January to 
March, which is a very high concentration of runoff compared to rivers in southern Australia 
(Petheram et al., 2008). While streamflow is ephemeral at many gauge sites, some rivers in the 
Gregory catchment are perennial (Table 2-4). Figure 2-44b illustrates that there is a high variation in 
monthly wet-season runoff from one year to the next. For example, during March, spatial mean 
runoff exceeded 34 mm in 20% of years and was less than 1 mm in 20% of years. The largest 
catchment mean annual runoff under Scenario A was 491 mm in 1973–74, and the smallest was 
3 mm in 1901–02 (Figure 2-44a). The CV of annual runoff aggregated across the Southern Gulf 
catchments is 1.2. Based on data from Petheram et al. (2008), this variability in annual runoff is 
slightly above the middle of the range of the annual variability in runoff of other rivers in northern 
Australia with a comparable mean annual runoff. 



\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\2_Hydrology\201_SG\1_GIS\1_Map_Documents\Hy-S-504_Rain_Runoff_1x2.mxd
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Figure 2-42 Mean annual (a) rainfall and (b) runoff across the Southern Gulf catchments under Scenario A 

Pixel-scale variation in mean annual runoff is due to changes in climate and modelled variation based on physiographic 
units. 




\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\2_Hydrology\201_SG\1_GIS\1_Map_Documents\Hy-S-505_20_50_80_runoff_1x3.mxd
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Figure 2-43 Annual runoff at (a) 20%, (b) 50% and (c) 80% exceedance across the Southern Gulf catchments under 
Scenario A 

Pixel-scale variation in mean annual runoff is due to changes in climate and modelled variation based on physiographic 
units. 



For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
Figure 2-44 Total runoff across the Southern Gulf catchments under Scenario A showing (a) time series of annual runoff 
and (b) monthly runoff averaged across the catchments 

The solid blue line in (a) is the 10-year running mean. In (b) ‘A range’ represents the 80% to 20% exceedance totals for 
that month. 

Flooding 

Intense seasonal rains from monsoonal bursts and tropical cyclones from November to March create 
flooding in parts of the Southern Gulf catchments and inundate large areas of floodplains, mostly in 
the downstream reaches between the Nicholson, Gregory and Leichhardt rivers. The floodplains 
along the Alexandra and Albert rivers are also heavily flooded (Figure 2-45). Floodplains along the 
Alexandra and Albert rivers (Figure 2-45) are also regularly flooded. Flooding is common in the 
Burketown area, which is located on a remnant of the main channel of the Albert River and 
represents the most eastward extent of a very flat ridgeline that provides the highest ground (~5 m 
above sea level) on the western bank of the river. Burketown is susceptible to flooding from the 
Albert River floodplain, as well as from overland flow paths within the town area. Flooding of the 
Albert River could also occur from floodwater breakout from the Nicholson or Gregory rivers. Rivers 


in the Southern Gulf catchments are largely unregulated. The notable exception is the Leichhardt 
River, which has two large dams: Moondarra Dam and Julius Dam. Overbank flow is generally 
governed by the topography of the floodplain. Since 1980, there have been 41 floods greater than or 
equal to 1 in 1 annual exceedance probability (AEP) in different parts of the Southern Gulf 
catchments. While floods occur in any month from November to April, historically the month with 
the most floods is January (42%). 

Characterising these flood events is important for a range of reasons. Flooding can be catastrophic to 
agricultural production in terms of loss of stock, pasture and topsoil, and damage to crops and 
infrastructure. It can also isolate properties and disrupt vehicle traffic providing goods and services to 
people in the catchment. However, flood events also provide opportunities for offstream wetlands to 
connect to the main river channel. The high biodiversity found in many unregulated floodplain 
systems in northern Australia is thought to largely depend on seasonal flood pulses, which allow 
biophysical exchanges to occur between rivers and offstream wetlands. 

Further observations of flood characteristics in the Southern Gulf catchments are as follows: 

• Flood peaks typically take about 2 days to travel from Gregory to Burketown at a mean speed of 
3.2 km/hour. 
• For flood events of AEP 1 in 2, 1 in 5 and 1 in 10, the peak discharges at Riversleigh Road on the 
Gregory River gauge are 590, 1850 and 2280 m3/second, respectively. 
• Between 1980 and 2023 (43 years), 51 streamflow events broke the banks of the Gregory River at 
Riversleigh Road crossing. All events occurred between November and April (inclusive), and about 
84% of these events occurred between January and March (inclusive). Of the ten largest flood peak 
discharges at Riversleigh on the Gregory River, six occurred in January, three in February and one in 
December. 
• The maximum area inundated by a flood event of AEP 1 in 38 that occurred in March 2023 was 
5983 km2 (Figure 2-46). 



 

Flood inundation, map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\2_Hydrology\201_SG\1_GIS\1_Map_Documents\HC-S-243_Inundation_MODIS_Flood_CR.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-45 Flood inundation map of the Southern Gulf catchments 

Data captured using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery. This figure illustrates the 
maximum percentage of each MODIS pixel inundated between 2000 and 2023. 

 





Lowland flood inundation, map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\2_Hydrology\201_SG\1_GIS\1_Map_Documents\HC-S-244_Flood_inundation.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-46 Flood inundation in the Southern Gulf catchments for a flood event of 1 in 38 annual exceedance 
probability (AEP) in March 2023 




Flood frequency in the Southern Gulf catchments 

Flood frequency analysis was performed for the Southern Gulf catchments to establish streamflow 
thresholds above which a flood event would occur. Flood frequencies were estimated for the three 
major rivers (Nicholson, Gregory and Leichhardt). For the Nicholson River, flood frequencies were 
estimated using streamflow observations from gauging station 912107A (Nicholson River at 
Connolly’s Hole) as this gauge has reasonable quality data. Flood frequencies were estimated using 
streamflow observations from gauging station 912105A (Gregory River at Riversleigh) for the Gregory 
River. For the Leichhardt River, flood frequencies were estimated using streamflow observations 
from gauging station 913007B (Leichhardt River at Floraville). Traditionally, flood frequencies are 
estimated based on maximum discharge for individual events. However, in the Assessment, to help 
determine the true magnitude of the events, the flood frequency analysis accounted for total flow 
volume as well as peak discharge for each event. This is motivated by the knowledge that the 
duration of an event, and not only its maximum discharge, can have a great impact on the inundated 
area. Figure 2-47 displays the relationship between peak flow, flood volume and AEP for the three 
gauges: one on the Nicholson River (912107A) one on the Gregory River (912105A) and one on the 
Leichhardt River (913007B). While flow volume is higher for larger floods, duration of flood is a key 
factor for volume of flood flow. 



A diagram of different colors
Description automatically generated with medium confidence
Figure 2-47 Peak flood discharge and annual exceedance probability (AEP) at (a) gauge 912107A (Nicholson River at 
Connolly’s Hole), (b) gauge 912105A (Gregory River at Riversleigh) and (c) gauge 913007B (Leichhardt River at 
Floraville) 

Colours indicate the total event volume of flood water in gigalitres (GL) for different events. 




Instream waterholes during the dry season 

The rivers in the Southern Gulf catchments are largely ephemeral. However, perennial flow is 
associated with discharge from the dolostone aquifer underlying the Barkly Tableland to the Gregory 
River. 

In ephemeral reaches, such as most of the Leichhardt River, once streamflow has ceased the rivers 
break up into a series of waterholes during the dry season. Waterholes that persist from one year to 
the next are considered to be key aquatic refugia and are likely to be sustaining ecosystems in the 
catchments (Section 3.2). In some reaches, waterholes may be partly or wholly sustained by 
groundwater discharge (Section 2.5.2). However, in other reaches there is little evidence that 
persistent waterholes receive water from groundwater discharge and are likely to be replenished 
following wet-season flows. Stream gauge data indicate that there is very little to no late dry-season 
flow for most locations along the Leichhardt River and most of the Nicholson River, while baseflow is 
apparent in Gregory River observations (Figure 2-48). These properties are reflected in the river 
model simulations for the month of October when any streamflow is likely the result of groundwater 
discharge into streams (Figure 2-49). Substantial baseflow in October in the Gregory system is related 
to discharge from the dolostone aquifer in the upper Gregory catchment. 

The ecological importance and functioning of key aquatic refugia are discussed in more detail in the 
companion technical report on ecological modelling (Ponce Reyes et al., 2024). 

 

"\\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\2_Hydrology\201_SG\0_Working\1_justin\5_Catchment_report\min_sept_flow.png"
Figure 2-48 Minimum observed September streamflow at two stream gauge locations on the Gregory River 




"\\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\2_Hydrology\201_SG\2_Reporting\1_Catch_report_river\03_minimumflow_boxplots\minOctoberFlow_v3.png"
Figure 2-49 Minimum monthly flow over 132 years of simulation for the month of October 

Assessed at locations indicated by labels in Figure 2-39. Locations are listed in an upstream to downstream order (left to 
right). The dashed blue horizontal lines equate to 200 ML/day, and the dotted red horizontal lines equate to 400 ML/day 

As an example, the formation of waterholes following a cease-to-flow event were captured using 
satellite imagery for a reach of the Flinders River in northern Australia (Figure 2-50). Figure 2-52 maps 
1 km river reaches (or segments) in the Southern Gulf catchments in which water is recorded in 
greater than 90% of dry-season satellite imagery. This is denoted the water index threshold and 
provides an indication of the river reaches that contain permanent water, typically waterholes that 
persist over the dry season. Some of these waterholes are maintained by perennial flow, for example, 
along the Gregory River. Below Gregory, the canopy along the Gregory River can be closed, obscuring 
the presence of water, and the river width becomes relatively small compared to the Landsat pixel 
size, which may influence the ability to detect permanent water using this technique. 




Maps of instream waterhole evolution.
For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
Figure 2-50 Instream waterhole evolution in a reach of the Flinders River 

This figure shows the area of waterholes in the reach of the river a given time after flow ceased and the ability of the 
water index threshold to track the change in waterhole area and distribution. 




Figure 2-51 The Leichhardt River near Kajabbi looking south towards the Isa highlands. In the highly seasonal climate of 
the Southern Gulf catchments, springs and persistent waterholes provide important ecological refugia during the dry 
season 

Photo: CSIRO – Nathan Dyer 




Permanent waterholes, map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\2_Hydrology\201_SG\1_GIS\1_Map_Documents\Hy-S-507_SouGulf_permanent_waterholes_v1.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au


Figure 2-52 Location of river reaches containing permanent water in the Southern Gulf catchments 
Persistent river reaches are defined as 1 km river reaches where water was identified in greater than 90% of the 
dry-season Landsat (Landsat 5, 7 and 8) imagery between 1989 and 2018. Mapping of persistent river reaches is 
confounded by riparian vegetation along the watercourses. 




Surface water quality 

Since the late 1960s, there has been systematic sampling of the water quality of the surface water 
system at the gauge network through the Surface Water Ambient Water Quality Network (SWAN) 
program in Queensland. Three sites remain open in the Southern Gulf Assessment area: Gregory 
River at Riversleigh (912105A), Gunpowder Creek at Gunpowder (913006A) and Leichhardt River at 
Floraville Homestead (913007B). The data available for regularly analysed water quality parameters 
of interest (of the over 60 samples at each site) are presented in Figure 2-54. Minimum, median and 
maximum statistics are also presented in Table 2-5. 

Environmental values define the suitable uses of the water by aquatic ecosystems and by humans 
(e.g. for drinking, irrigation, aquaculture, recreation), and water quality objectives define objectives 
for the physical, chemical and biological characteristics of the water (e.g. nitrogen content, dissolved 
oxygen, turbidity, toxicants, fish). Environmental values and water quality objectives are being 
progressively determined for Queensland waters but have not yet been developed for any Southern 
Gulf rivers. In the absence of local water quality objectives, the water quality data can be interpreted 
against national guidelines. Salinity concentrations were typically within safe drinking limits 
(<1000 μS/cm). The maximum value at the Gunpowder Creek site (Table 2-5) coincided with zero 
discharge, indicating these higher salinities are likely due to the evaporative concentration of water 
at the sampling location rather than representing water quality of the source water. 

Table 2-5 Summary of water quality data for the open Southern Gulf catchments sites, with values of minimum, 
median and maximum for each site and each water quality parameter 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
†NTU = nephelometric turbidity units. 
‡ below detection limit represented by zero value. 

All recorded metal concentrations were below livestock drinking water trigger values from ANZECC 
and ARMCANZ (2000). Median constituent concentrations were well below long-term (100 year) 
trigger values for heavy metals and nutrients for irrigation water; however, a small number of 
samples exceeded the iron (0.2 mg/L) and phosphorus (0.05 mg/L) guidelines. All samples were 
above the national guideline values for total phosphorous for ecosystems in tropical lowland rivers 
(0.1 mg/L), and 34% of samples were above the national guideline values for total nitrogen 
(0.3 mg/L). This does not necessarily mean poor-quality water, as both Queensland’s Environmental 
Protection Policy (Water) and the national guidelines highlight the importance of using guideline 
values tailored to the local environment. 


A number of studies have investigated the water quality of the upper Leichhardt River, associated 
with mining activity, urban runoff and water supply to Mount Isa. Wilson et al. (2007) sampled 
disconnected dry-season remnant waterholes of the Leichhardt River upstream of Lake Moondarra. 
They found guideline values for healthy ecosystems for water soluble metals were exceeded, and a 
number of sites were found to be unfit for primary human contact. Mount Isa city’s sewerage 
infrastructure, associated waste water reuse scheme, and mining and smelting activities were 
identified as contributors to impaired water quality, highlighting the need for a catchment 
management approach to water quality improvement. The Lead Pathways Study investigated sources 
and pathways of heavy metals (primarily lead) to land, air and water at Mount Isa, including the 
Leichhardt River (Noller et al., 2012). Five sampling periods encompassing times before, during and 
after the wet season, were conducted from 2008 to 2010. A number of sites exceeded the ANZECC 
and ARMCANZ Water Quality Guidelines’ 90% and 95% trigger values for freshwater species for 
arsenic, cadmium, copper and lead. The water quality guideline process indicates further 
investigation should be undertaken to assess potential impacts on ecological health. The drinking 
water source for Mount Isa (Lake Moondarra) was found to meet drinking water guidelines, and 
sampled metal concentrations indicated a low risk to human health from recreational activities or 
eating fish caught in the lake or Leichhardt River. 

 


Figure 2-53 Accelerated erosion contributes sediment to streamflow 

Photo: CSIRO – Nathan Dyer 

 




For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 2-54 Water quality samples for selected constituents on the Gregory River at Riversleigh (A912005A), 
Gunpowder Creek at Gunpowder (913006A) and Leichhardt River at Floraville Homestead (913007B) 

Values below detection limits are seen as constant values, for example, 0.01 mg/L for zinc and 0.05 mg/L for aluminium. 
Horizontal dashed line represents national guideline levels where relevant. NTU = nephelometric turbidity units. 

Data sourced from Queensland Government website 



2.6 References 

ANZECC and ARMCANZ (2000) Australian and New Zealand guidelines for fresh and marine water 
quality, Volume 1, The guidelines. Australian and New Zealand Environment and Conservation 
Council, Agriculture and Resource Management Council of Australia and New Zealand. 

Bardwell N and Grey D (2016) Hydrogeochemistry of Queensland: data release: accompanying notes. 
CSIRO, Australia. Viewed 23 September 2021, https://researchdata.edu.au/hydrogeochemistry-
queensland-data-release/671735. 

BOM (2023) Tropical cyclone databases. Bureau of Meteorology, Canberra. Viewed 6 February 2023, Hyperlink to: Tropical cyclone databases
. 

Bowman DMJS, Brown GK, Braby MF, Brown JR, Cook LG, Crisp MD, Ford F, Haberle S, Hughes J, Isagi 
Y, Joseph L, McBride J, Nelson G and Ladiges PY (2010) Biogeography of the Australian monsoon 
tropics. Journal of Biogeography 37(2), 201–216. Hyperlink to: Biogeography of the Australian monsoon tropics
. 

Bradshaw BE, Lahtinen AC, Khider K, Ryan DJ, Colwell JB, Chirinos A and Bradshaw J (2009) 
Queensland carbon dioxide geological storage atlas. Greenhouse Gas Storage Solutions, 
Canberra for the Queensland Department of Employment, Economic Development and 
Innovation, Brisbane. 

Buchanan S, Dixon-Jain P, Martinez JL, Raiber M and Kumar P (2020) Hydrogeology and groundwater 
systems for the Isa GBA region. Technical appendix for the Geological and bioregional 
assessment: stage 2. Department of the Environment and Energy, Bureau of Meteorology, 
CSIRO and Geoscience Australia, Australia. 

Bureau of Meteorology, 2017. Groundwater Dependent Ecosystems Atlas. 
http://www.bom.gov.au/water/groundwater/gde/map.shtml 

Charles S, Petheram C, Berthet A, Browning G, Hodgson G, Wheeler M, Yang A, Gallant S, Vaze J, 
Wang B, Marshall A, Hendon H, Kuleshov Y, Dowdy A, Reid P, Read A, Feikema P, Hapuarachchi 
P, Smith T, Gregory P and Shi L (2017) Climate data and their characterisation for hydrological 
and agricultural scenario modelling across the Fitzroy, Darwin and Mitchell catchments. A 
technical report to the Australian Government from the CSIRO Northern Australia Water 
Resource Assessment, part of the National Water Infrastructure Development Fund: Water 
Resource Assessments. CSIRO, Australia. 

Chiew F, Post D and Moran R (2012) Hydroclimate baseline and future water availability projections 
for water resources planning. 34th Hydrology and Water Resources Symposium 2012, Sydney, 
NSW, 19–22 November 2012. Engineers Australia, Barton, 461–468. 

Chiew FHS, Cai W and Smith IN (2009) Advice on defining climate scenarios for use in Murray–Darling 
Basin Authority Basin Plan modelling. CSIRO report for the Murray–Darling Basin Authority. 

Christian CS, Noakes LC, Perry RA, Slatyer RO, Stewart GA, Traves DM and Csiro (1954) Survey of the 
Barkly Region, Northern Territory and Queensland, 1947–48. Land Research Series No.3. 

CoastAdapt (2017) Sea-level rise and future climate information for coastal councils: Roper Gulf, NT. 
National Climate Change Adaptation Research Facility and Australian Government Department 
of Environment and Energy. Viewed 03 May 2018, Hyperlink to: CoastAdapt Roper Gulf, NT
. 


CSIRO (2009a) Water in the Van Diemen region. In: Water in the Timor Sea Drainage Division. A 
report to the Australian Government from the CSIRO Northern Australia Sustainable Yields 
Project. CSIRO Water for a Healthy Country Flagship, Australia, 363–452. 

CSIRO (2009b) Water in the South-West Gulf region. In: Water in the Gulf of Carpentaria Drainage 
Division. A report to the Australian Government from the CSIRO Northern Australia Sustainable 
Yields Project. CSIRO Water for a Healthy Country Flagship, Australia, 123–197. Viewed 
23 September 2021, Hyperlink to: Water in the Gulf of Carpentaria Drainage Division
. 

CSIRO (2009c) Water in the Gulf of Carpentaria Drainage Division. A report to the Australian 
Government from the CSIRO Northern Australia Sustainable Yields Project. CSIRO Water for a 
Healthy Country Flagship, Australia. Viewed 23 September 2021, Hyperlink to: Water in the Gulf of Carpentaria Drainage Division
. 

CSIRO and Bureau of Meteorology (2015) Climate change in Australia. Information for Australia’s 
natural resource management regions: technical report. CSIRO and Bureau of Meteorology, 
Australia. 

Denniston RF, Villarini G, Gonzales AN, Wyrwoll K-H, Polyak VJ, Ummenhofer CC, Lachniet MS, 
Wanamaker AD, Humphreys WF, Woods D and Cugley J (2015) Extreme rainfall activity in the 
Australian tropics reflects changes in the El Niño/Southern Oscillation over the last two 
millennia. Proceedings of the National Academy of Sciences 112(15), 4576-4581. Hyperlink to: Extreme rainfall activity in the Australian tropics reflects changes in the El Niño/Southern Oscillation over the last two millennia
. 

DENR (2016) Bore construction Darwin rural area most common in dolomite country. Department of 
Environment and Natural Resources. Data downloaded in September 2022, Hyperlink to: Bore construction Darwin rural area most common in dolomite country (figure) 
. 

Department of Environment, Parks and Water Security (2008) Northern Territory groundwater – 
aquifer types 1:2,000,000. Northern Territory Department of Environment, Parks and Water 
Security, Darwin. Data downloaded in February 2021, Hyperlink to: Northern Territory groundwater – aquifer types
. 

Department of Environment, Parks and Water Security (2013) Northern Territory springs. Northern 
Territory Department of Environment, Parks and Water Security, Darwin. Data downloaded in 
February 2021, Hyperlink to: Northern Territory Springs
. 

Department of Environment, Parks and Water Security (2014) Digital groundwater database for the 
Northern Territory, supplied by the Department of Environment, Parks and Water Security, 
Copyright – Northern Territory of Australia. Data downloaded from the Northern Territory 
Government (NTG) Open Data Portal in September 2021, https://data.nt.gov.au/dataset/nt-
water-groundwater-licence-extraction-points. 

Department of Industry, Tourism and Trade (2014) Northern Territory geological map (interp) 2500K. 
Northern Territory Department of Industry, Tourism and Trade, Darwin. Data downloaded in 
February 2023, Hyperlink to: Northern Territory Geological map (interp) 2500K
. 

Dixon-Jain P, Bishop C, Lester J, Orlov C, McPherson A, Pho G, Flower C, Lawson S and Lewis S (2024) 
Hydrogeology and groundwater systems of the South Nicholson and Georgina basins, 


Queensland and Northern Territory. Record 2024/37, Geoscience Australia, Canberra. 

DNRME (Queensland Department of Natural Resources, Mines and Energy) (2023) Groundwater 
database – Queensland. Open Data Portal. Hyperlink to: Groundwater database – Queensland
. 

DNRME (2021) Groundwater database – Queensland. Database storing registered water bore data 
from private water bores and Queensland Government groundwater investigation and 
monitoring bores. State of Queensland, Department of Resources. Licensed under Single 
Supply, licence sourced in September 2021. Viewed 23 September 2021, Hyperlink to: Groundwater Database - Queensland
. 

Environment Australia (2001) A directory of important wetlands in Australia, 3rd edn. Environment 
Australia, Canberra. 

Evans S, Marchand R and Ackerman T (2014) Variability of the Australian monsoon and precipitation 
trends at Darwin. Journal of Climate 27(22), 8487–8500. Hyperlink to: Variability of the Australian monsoon and precipitation trends at Darwin
. 

Exploring for the future (n.d.) Project activity: South Nicholson National Drilling Initiative. Geoscience 
Australia website. Viewed January 2024, Hyperlink to: South Nicholson National Drilling Initiative
. 

Fitzpatrick EA (1986) An introduction to soil science. Longman Scientific and Technical Group, Essex, 
UK. 

Forsyth AJ, Nott J and Bateman MD (2010) Beach ridge plain evidence of a variable late-Holocene 
tropical cyclone climate, North Queensland, Australia. Palaeogeography, Palaeoclimatology, 
Palaeoecology 297(3–4), 707-716. Hyperlink to: Beach ridge plain evidence of a variable late-Holocene tropical cyclone climate, North Queensland, Australia
. 

Geoscience Australia and Australian Stratigraphy Commission (2021) Australian stratigraphic units 
database. Viewed 17 January 2024, https://www.ga.gov.au/data-
pubs/datastandards/stratigraphic-units. 

Gibbs M, Hughes J, Yang A, Wang B, Marvanek S and Petheram C (2024) River model scenario analysis 
for the Southern Gulf catchments. A technical report from the CSIRO Southern Gulf Water 
Resource Assessment for the National Water Grid. CSIRO, Australia. 

Grimes KG (1974) Mesozoic and Cainozoic geology of the Lawn Hill, Westmoreland, Mornington, and 
Cape Van Diemen 1:250 000 Sheet areas, Queensland. Record 1974/106. Geoscience Australia, 
Canberra. Viewed 19 December 2023, Hyperlink to: Mesozoic and Cainozoic geology of the Lawn Hill, Westmoreland, Mornington, and Cape Van Diemen 1:250 000 Sheet areas, Queensland
. 

Haig J, Nott J and Reichart G-J (2014) Australian tropical cyclone activity lower than at any time over 
the past 550–1,500 years. Nature 505(7485), 667-671. Hyperlink to: Australian tropical cyclone activity lower than at any time over the past 550-1,500 years
. 

Hausfather Z and Peters GP (2020) Emissions–the ‘business as usual’ story is misleading. Nature 577, 
618-620. 

Herbert GC (2000) Hydrogeology of the Karumba Basin western Cape York Peninsula. Post graduate 
diploma project, University of Queensland, School of Natural Resource Sciences, Brisbane. 


Horn AM, Derrington EA, Herbert GC, Lait RW and Hillier JR (1995) Groundwater resources of Cape 
York Peninsula. Cape York Peninsula land use strategy, Office of the Co-ordinator General of 
Queensland, Brisbane, Department of the Environment, Sport and Territories, Canberra, 
Queensland Department of Primary Industries, Brisbane and Mareeba, and Australian 
Geological Survey Organisation, Mareeba. 

Ingram JA (1972) 1:250,000 Geological series – explanatory notes, Donors Hill, Queensland, Sheet 
SE/54-10 International Index. Canberra. 

IPCC (2022) Climate Change 2022: impacts, adaptation, and vulnerability. Contribution of Working 
Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. 
Cambridge University Press. Cambridge University Press, Cambridge, UK and New York, NY, 
USA. 

Isbell, RF and CSIRO (2016) The Australian Soil Classification. Australian Soil and Land Survey 
Handbook Series (Vol. 4), 2nd ed. CSIRO Publishing, Melbourne. 

Jeffrey SJ, Carter JO, Moodie KB and Beswick AR (2001) Using spatial interpolation to construct a 
comprehensive archive of Australian climate data. Environmental Modelling and Software 16, 
309–330. Hyperlink to: Using spatial interpolation to construct a comprehensive archive of Australian climate data
. 

Jenny H (1941) Factors of soil formation, a system of quantitative pedology. McGraw-Hill, New York. 

Jolly P and Tickell S (2011) Tufa dams of Northern Australia. NT branch of International Association of 
Hydrologists (IAH) Australia. 

Klohn Crippen Berger (2016) Hydrogeological assessment of the Great Artesian Basin: 
characterisation of aquifer groups, Carpentaria Basin. Department of Natural Resources and 
Mines (Queensland), Brisbane. 

Köppen W (1936) Das geographische System der Klimate. In: Köppen W and Geiger G (eds), 
Handbuch der Klimatologie, 1. C. Gebr, Borntraeger, 1–44. 

Kruse P and Dunster J (2013) Chapter 28: Georgina Basin. In: Ahmad M and Munson TJ (compilers) 
Geology and mineral resources of the Northern Territory. Northern Territory Geological Survey, 
Special Publication 5. 

Lerat J, Egan C, Kim S, Gooda M, Loy A, Shao Q and Petheram C (2013) Calibration of river models for 
the Flinders and Gilbert catchments. A technical report to the Australian Government from the 
CSIRO Flinders and Gilbert Agricultural Resource Assessment, part of the North Queensland 
Irrigated Agriculture Strategy. CSIRO Water for a Healthy Country and Sustainable Agriculture 
flagships, Australia. 

Matthews I (1992) Alpurrurulam (Lake Nash) groundwater source and borefield review. Power and 
Water Authority. Technical Report WRA92008. Viewed 23 September 2021, Hyperlink to: Alpurrurulam groundwater source and borefield review
. 

McBride JL and Nicholls N (1983) Seasonal relationships between Australian rainfall and the Southern 
Oscillation. Monthly Weather Review 111(10), 1998–2004. Hyperlink to: Seasonal relationships between Australian rainfall and the Southern Oscillation
. 


McEniery M (1980) Groundwater resources – north Queensland. In: Henderson R and Stephenson P 
(eds) The geology and geophysics of northeastern Australia, Volume 1. Geological Society of 
Australia, Queensland, Brisbane. 

McFarlane D, Stone R, Martens S, Thomas J, Silberstein R, Ali R and Hodgson G (2012) Climate change 
impacts on water yields and demands in south-western Australia. Journal of Hydrology 475, 
488–498. Hyperlink to: Climate change impacts on water yields and demands in south-western Australia
. 

McJannet D, Yang A and Seo L (2023) Climate data characterisation for hydrological and agricultural 
scenario modelling across the Victoria, Roper and Southern Gulf catchments. A technical report 
from the CSIRO Victoria River and Southern Gulf Water Resource Assessments for the National 
Water Grid. CSIRO, Australia. 

McMahon TA and Adeloye AJ (2005) Water resources yield. Water Resources Publications LLC, 
Colorado, USA. 

Ponce Reyes R, Stratford D, Linke S, Merrin L, Kenyon R, Buckworth R, Deng RA, Hughes J, McGinness 
H, Pritchard J, Seo L and Waltham N (2024) Assessment of the potential ecological outcomes of 
water resource development in the Southern Gulf catchments. A technical report from the 
CSIRO Southern Gulf Water Resource Assessment for the National Water Grid. CSIRO, Australia. 

National Committee on Soil and Terrain (2009) Australian soil and land survey field handbook. CSIRO 
Publishing, Collingwood. 

Noller B, Huynh T, Ng J, Zheng J and Harris H (2012) Lead pathways study – Water: sources and 
pathways of contaminants to the Leichhardt River. Centre for Mined Land Rehabilitation – 
Sustainable Minerals Institute, The University of Queensland, Report prepared for Mount Isa 
Mines Limited. Brisbane, Queensland. 

Nott JF and Jagger TH (2013) Deriving robust return periods for tropical cyclone inundations from 
sediments. Geophysical Research Letters 40(2), 370–373. Hyperlink to: Deriving robust return periods for tropical cyclone inundations from sediments
. 

Peel MC, Finlayson BL and McMahon TA (2007) Updated world map of the Köppen–Geiger climate 
classification. Hydrology and Earth System Science 11(5), 1633–1644. Hyperlink to: Updated world map of the Köppen-Geiger climate classification
. 

Petheram C and Yang A (2013) Climate data and their characterisation for hydrological and 
agricultural scenario modelling across the Flinders and Gilbert catchments. A technical report to 
the Australian Government from the CSIRO Flinders and Gilbert Agricultural Resource 
Assessment, part of the North Queensland Irrigated Agriculture Strategy. CSIRO Water for a 
Healthy Country and Sustainable Agriculture flagships, Australia. Viewed 6 February 2018, Hyperlink to: Climate data and their characterisation for hydrological and agricultural scenario modelling across the Flinders and Gilbert catchments
. 

Petheram C, Gallant J, Wilson P, Stone P, Eades G, Roger L, Read A, Tickell S, Commander P, Moon A, 
McFarlane D and Marvanek S (2014) Northern rivers and dams: a preliminary assessment of 
surface water storage potential for northern Australia. CSIRO Land and Water Flagship 
Technical Report. CSIRO, Australia. 

Petheram C, McMahon TA and Peel MC (2008) Flow characteristics of rivers in northern Australia: 
implications for development. Journal of Hydrology 357(1–2), 93–111. Hyperlink to: Flow characteristics of rivers in northern Australia: implications for development
. 


Petheram C, McMahon TA, Peel MC and Smith CJ (2010) A continental scale assessment of Australia's 
potential for irrigation. Water Resources Management 24(9), 1791–1817. Hyperlink to: A continental scale assessment of Australia's potential for irrigation
.

Petheram C, Rogers L, Read A, Gallant J, Moon A, Yang A, Gonzalez D, Seo L, Marvanek S, Hughes J, 
Ponce Reyes R, Wilson P, Wang B, Ticehurst C and Barber M (2017) Assessment of surface 
water storage options in the Fitzroy, Darwin and Mitchell catchments. A technical report to the 
Australian Government from the CSIRO Northern Australia Water Resource Assessment, part of 
the National Water Infrastructure Development Fund: Water Resource Assessments. CSIRO, 
Australia. 

Petheram C, Rustomji P, McVicar TR, Cai W, Chiew FHS, Vleeshouwer J, Van Niel TG, Li L, 
Cresswell RG, Donohue RJ, Teng J and Perraud J-M (2012) Estimating the impact of projected 
climate change on runoff across the tropical savannas and semiarid rangelands of northern 
Australia. Journal of Hydrometeorology 13(2), 483–503. Hyperlink to: Estimating the impact of projected climate change on runoff across the tropical savannas and semiarid rangelands of northern Australia
. 

Petheram C, Walker G, Grayson R, Thierfelder T and Zhang L (2002) Towards a framework for 
predicting impacts of land-use on recharge: 1. A review of recharge studies in Australia. Soil 
Research 40, 397–417. Hyperlink to: Towards a framework for predicting impacts of land-use on recharge: 1. A review of recharge studies in Australia
. 

Peverill KI, Sparrow LA and Reuter DJ (eds) (1999) Soil analysis: an interpretation manual. CSIRO 
Publishing, Collingwood, Victoria. 

Queensland Government (2021) Springs database. 
(https://www.data.qld.gov.au/dataset/springs#:~:text=The%20Queensland%20Springs%20Database%20provides%20a%20comprehensive%20catalogue,and%20any%20associated%20surface%20expression%20groundwater%20dependent%20ecosystems.). 

Radke BM, Kellett JR, Ransley TR and Bell J (2012) Lexicon of the lithostratigraphic and 
hydrogeological units of the Great Artesian Basin and its Cenozoic cover. A technical report to 
the Australian Government from the CSIRO Great Artesian Basin Water Resource Assessment, 
Australian Government. CSIRO Water for a Healthy Country Flagship, Australia. 

Raiber M, Suckow A, Deslandes A, Gerber C, Martinez J, Crane P, Ransley T, Evans T, Wallace L and 
Wu G (2022) Assessing recharge processes and flow dynamics using environmental tracers in 
the Great Artesian Basin. CSIRO, Australia. 

Raiber M, Taylor AR, Dupuy M, Priestley S, Crosbie RS, Knapton A, Hodgson G and Barry K (2024) 
Characterising groundwater resources of the Gilbert River Formation, Camooweal Dolostone 
and Thorntonia Limestone in the Southern Gulf catchments, Queensland and Northern 
Territory. A technical report from the CSIRO Southern Gulf Water Resource Assessment for the 
National Water Grid. CSIRO, Australia. 

Randal MA (1966) 1:250,000 Geological series – explanatory notes, Rankin, N.T. Sheet SE/53-16. 
Canberra. 

Rasmusson EM and Arkin PA (1993) A global view of large-scale precipitation variability. Journal of 
Climate 6, 1495–1522. Hyperlink to: A global view of large-scale precipitation variability
. 

Raymond OL, Liu S, Gallagher R, Zhang W and Highet LM (2012) Surface Geology of Australia 1:1 
million scale dataset 2012 edition. Geoscience Australia, Canberra. 
http://pid.geoscience.gov.au/dataset/ga/74619. 


Raymond OL (2018) Australian geological provinces 2018.01 edition. Geoscience Australia, Canberra. 
Viewed 18 October 2020, Hyperlink to: Australian geological provinces 2018.01 edition (database)
. 

Read R (2003) Avon Downs and Ranken sheets groundwater occurrence. Northern Territory 
Department of Infrastructure, Planning and Environment, Natural Resources Division, Report 
40/2003A. 

Smerdon BD, Ransley TR, Radke BM and Kellett JR (2012) Water resource assessment for the Great 
Artesian Basin. A report to the Australian Government from the CSIRO Great Artesian Basin 
Water Resource Assessment. CSIRO Water for a Healthy Country Flagship, Australia. Viewed 
23 September 2021, Hyperlink to: Water resource assessment for the Great Artesian Basin
. 

Smith JW and Roberts HG (1972) Mount Drummond, Northern Territory: 1:250,000 Geological series 
– explanatory notes. Record SE5312. Canberra. 

Taylor AR, Barron OV, Harrington GA, Chilcott C, Davies PJ, Wohling DL and Gilfedder M (2021) Rapid 
appraisal of new groundwater-based irrigation infrastructure opportunities across Australia. A 
technical report from CSIRO to the National Water Grid Authority. CSIRO, Australia. 

Thomas M, Philip S, Zund P, Stockmann U, Hill J, Gregory L, Watson I and Thomas E (2024) Soils and 
land suitability for the Southern Gulf catchments. A technical report from the CSIRO Southern 
Gulf Water Resource Assessment for the National Water Grid. CSIRO, Australia. 

Tickell SJ (2003) Water resource mapping Barkly Tablelands. Report 23/2003. Department of 
Infrastructure Planning and Environment Natural Systems Division, Darwin. Viewed 
23 September 2021, Hyperlink to: Water Resource Mapping Barkly Tablelands
. 

Tickell SJ and Bruwer Q (2017) Georgina Basin groundwater assessment: Daly Waters to Tennant 
Creek. Technical Report 17/2017. Department of Environment and Natural Resources, 
Palmerston. 

Twidale CF (1956) The physiography of northwest Queensland. Geographic Studies 3(1). 

Wilson AL, Dehaan RL, Watts RJ, Page KJ, Bowmer KH and Curtis A (eds) (2007) Proceedings of the 5th 
Australian Stream Management Conference. Australian rivers: making a difference. Charles 
Sturt University, Thurgoona, New South Wales. 


3 Living and built environment of the Southern Gulf 
catchments 

Authors: Pethie Lyons, Linda Merrin, Seonaid Philip, Diane Jarvis, Thomas Vanderbyl, 
Danial Stratford, Rob Kenyon, Simon Linke, Rocio Ponce Reyes, Heather McGinness, Caroline Bruce, 
Kaylene Camuti, Andrew R Taylor, Nathan Waltham, Jodie Pritchard 

Chapter 3 discusses a wide range of considerations relating to the living components of the 
catchments of the Southern Gulf rivers, that is Settlement Creek, Gregory–Nicholson River and 
Leichhardt River, the Morning Inlet catchments and the Wellesley island groups.1 This includes the 
environments that support these components, the people who live in the catchments or have 
strong ties to it, and the existing transport, power and water infrastructure. 

1 Only those islands greater than 1000 ha are mapped 

The key components and concepts of Chapter 3 are shown in Figure 3-1. 



Figure 3-1 Schematic diagram of key components of the living and built environment to be considered in 
establishing a greenfield irrigation development 

Numbers refer to sections in this chapter. 

Block diagram of chapter sections
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\1_All\9_Graphics_artist\3_Vic and SoG\C Bruce Vic CR Chp3_8_2024.jpg
For more information on this figure please contact CSIRO on enquiries@csiro.au

3.1 Summary 

This chapter provides information on the living and built environment, including information about 
the people, the ecology, the infrastructure and the institutional context of the Southern Gulf 
catchments. It also examines the values, rights, interests and development objectives of 
Indigenous Peoples. 

3.1.1 Key findings 











Ecology 
The largely intact habitats and landscapes of the Southern Gulf catchments provide ecosystem 
services that support high biodiversity, recreational activities, tourism, traditional and commercial 
fisheries, mining and areas of agricultural production. Within the freshwater sections of the 
Southern Gulf catchments are extensive areas with high habitat values, including ephemeral and 
persistent rivers, wetlands, floodplains and groundwater-dependent ecosystems (GDEs), including 
13 sites listed in the Directory of Important Wetlands in Australia. Flows from the rivers and creeks 
in the Southern Gulf catchments into the Gulf of Carpentaria support recreational and commercial 
fisheries including barramundi (Lates calcarifer) and prawn fisheries. 
The Southern Gulf catchments support some of northern Australia’s most iconic wildlife species, 
including freshwater sawfish (Pristis pristis; listed as Vulnerable under the Commonwealth 
Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)), marine turtles and 
dugong (Dugong dugon) that occur in the coastal waters of the Gulf of Carpentaria. A wide variety 
of waterbirds can be found throughout the catchments as well as many lesser-known plants and 
animals that are also of great conservation significance (Atlas of Living Australia, 2021). 
Changes in land and water resources can have serious consequences for the ecology of rivers. 
Water resource development that changes the magnitude, timing or duration of either low or high 
flows can affect species, habitats and ecological processes such as connectivity. Water resource 
development can also facilitate or exacerbate other impacts, including the spread or 
establishment of invasive species, increases in other anthropogenic pressures, and changes to 
water quality, including the availability and distribution of nutrients. 
Demographics, industries and infrastructure 
The Southern Gulf catchments have a population of about 22,500, with a population density 
one-sixteenth that of Australia as a whole. The study area contains one significant urban area 
(population >10,000 people), namely, the city of Mount Isa (over 18,000 people). There are several 
small towns and communities within the catchments, including Burketown, Doomadgee and 
Kajabbi and Gununa on the Wellesley Islands. Of these settlements, only Doomadgee (population 
1387 as at the 2021 Census) has a population greater than 1000. Residents of the Southern Gulf 
catchments tend to be younger and more likely to identify as Indigenous than the typical resident 
of Queensland and of Australia as a whole. Incomes differ from the national and state mean, but 
the direction of the difference depends on the part of the population in question: incomes for the 
people of Mount Isa are higher than the state and national average while incomes of residents of 
the remainder of the study area are lower on average. 
102 | Water resource assessment for the Southern Gulf catchments 


Excluding Mount Isa data from the analysis because it is heavily skewed to mining, the data reveal 
that agriculture provides 17.5% of employment. The dominant land use in the Southern Gulf 
catchments is grazing (77%). Conservation and protected land occupy 16% of the catchments and 
water and wetlands occupy another 3.8%. In terms of land tenure, 12% of the Southern Gulf 
catchments is held as Aboriginal freehold. The gross value of agricultural production (GVAP) in the 
Southern Gulf catchments is approximately $243.6 million, of which beef cattle contribute around 
$242.7 million and cropping accounts for the remaining $0.9 million. 

The Southern Gulf catchments are serviced by a modest network of major roads. The Barkly 
Highway is the only sealed road between the NT and Queensland. Type 2 road trains (vehicles up 
to 53 m in length) have access to a large percentage of the pastoral enterprises, providing onward 
access east to the Port of Townsville, south to markets and west into the NT. A good-quality rail 
line, which provides a link to Townsville and its port, can be accessed at Mount Isa. 

The North West Power System (NWPS) is centred in Mount Isa. The only other location receiving 
high voltage power in the Southern Gulf catchments is the Century Mine (zinc) near Lawn Hill from 
an approximately 250 km branch. Doomadgee, Burketown and Gununa have their own power 
stations. The smaller communities are very remote and serviced by stand-alone diesel-powered 
off-grid electricity generation facilities. 

Large water storages are found in the North West Minerals Province of the Southern Gulf 
catchments. The two major storages, Lake Moondarra (107 GL capacity) and Lake Julius (107 GL 
capacity), are both on the Leichhardt River. They provide a reliable potable water supply to Mount 
Isa and through transmission pipelines to mining enterprises in the study area. The North West 
Queensland Water Pipeline from Lake Julius also supplies water to Ernest Henry Mine and 
Cloncurry, both in the neighbouring Flinders catchment. Other large water storages are directly 
linked to mining, with two large on-property water storage facilities supporting small-scale 
irrigation development with surface water allocations of between 1000 and 8000 ML/year. 

Some moderate surface water licences drawing water from permanent rivers (between 400 and 
1000 ML/year) have been granted for town and community water supply. Much smaller surface 
water licences (<50 ML/year) are associated with stock use. Currently 13 groundwater licences 
have been granted for a variety of applications. The largest entitlements (150 to 1400 ML/year) 
are associated with industrial use in mining. Two licensed entitlements of approximately 
100 ML/year have been granted for town and community water supplies, and the smallest 
groundwater licences (<100 ML/year) have been granted for a variety of industrial and agricultural 
uses. Groundwater is sourced from a variety of aquifers hosted in different geological units. 

Indigenous values and development objectives 

This section gives an overview of the information needed on Indigenous water issues in the 
Assessment area to provide foundations for community consultations and involvement in further 
research, and planning and decision making with government and industry. The sub-project 
focuses on publicly available literature with additional material to be provided through discussions 
with Indigenous land-owning groups within the catchments. The literature review includes the 
previous Northern Australia Water Resource Assessment reports on Indigenous water rights, 
values, interests and development goals; publications on Indigenous water values and the 


colonisation of northern Australia; and reports related to development in the Southern Gulf 
catchments. 

The language groups of this Assessment area are: 


•Leichhardt catchment – Kalkadoon, Mitakoodi, Wakabunga, Mayi-Kutuna, Mayi-Thankurti, 
Mayi-Yapi, Mayi-Yali and Kukatj•Nicholson catchment – Waanyi, Garawa, Wakabunga, Nguburinji, and Gangalidda•Wellesley Islands – Lardil, Yangkaal, Kaiadilt•Settlement catchment – Garawa, Gangalidda•Morning Inlet catchment – Kukatj.


This sub-project builds on findings from the consultations with Indigenous Peoples from the 
previously conducted Northern Australia Water Resource Assessment reports to offer a regionally 
specific assessment designed to help non-Indigenous decision makers and others understand 
general Indigenous valuations of water and relationships to Country and the rights and interests 
attached to those. It highlights Indigenous perspectives on water-related development, 
development objectives, and cultural heritage concerns related to access to pastoral and mining 
leases and Indigenous land and water management and responsibilities. Studies in the mining and 
community sectors demonstrate increasing concerns about the cumulative impact of development 
on groundwater and surface water supply and quality. 

Indigenous Peoples and the groups they belong to have significant land holdings and rights in 
Country through: 

•the Commonwealth Aboriginal Land Rights (Northern Territory) Act 1976 (ALRA)
•the Northern Territory Aboriginal Sacred Sites Act 1989 (NT)
•Queensland Aboriginal Land Act 1991 (ALA) deeds of grant in trust (DOGIT)
•native title determinations exclusive and non-exclusive (Queensland)
•the Queensland Aboriginal Cultural Heritage Act 2003
•Indigenous Land Use Agreements (ILUAs) (Queensland).


Indigenous Peoples within the catchments have a long history of engaging with development 
interests in pastoralism and mining, two sectors that influence contemporary water values. 
Indigenous owners in the catchments have actively negotiated with sector development interests 
to facilitate aligning their economic viability and sustainability objectives with cultural and 
environmental goals. There are examples of business development successes with Kalkadoon 
Native Title Aboriginal Corporation Registered Native Title Body Corporate (RNTBC) and the 
Waanyi People through business partnerships with mining companies. The Lawn Hill and 
Riversleigh Pastoral Holding Company is a significant agreement that supports the economic 
development of Waanyi People. However, broader development outcomes of expanding human 
capability and establishing new regional opportunities are not yet being realised. Ranger groups 
are engaged in fee-for-service work and, more broadly, environmental management, including 
collaborations with Southern Gulf Natural Resource Management (NRM) in Queensland. 
Indigenous representative agencies and industry more broadly are currently being engaged by the 
Queensland Government in reviewing the Water Plan (Gulf) 2007 (Queensland Government, 2007). 
104 | Water resource assessment for the Southern Gulf catchments 


Queensland Government in reviewing the Water Plan (Gulf) 2007 (Queensland Government, 
2007). 

Legal and policy environment 

Proponents must be aware of the complex legal, policy and regulatory landscape when 
contemplating and planning land and water developments within the Southern Gulf catchments. 
As part of their due diligence process, proponents must secure appropriate land tenure, secure 
the necessary authorisations to take water, and obtain a range of government approvals prior to 
commencing construction and operation of a development. The Southern Gulf catchments 
straddle the border between the NT and Queensland. This means that government powers and 
responsibilities for managing land and water resources in the Southern Gulf catchments are 
shared between the Australian Government, the NT and Queensland governments and local 
governments. The NT and Queensland governments have primary responsibility for land, water 
and environmental policy and laws. The Australian Government has powers under the EPBC Act 
relating to matters of national environmental significance (including those arising from the World 
Heritage Convention, the Ramsar Convention on Wetlands of International Importance and the 
Convention on Biological Diversity) and the native title rights of Indigenous Peoples. Local 
governments are established within the states and territories. In Queensland, these have 
responsibility for land use planning, which involves establishing local planning schemes that 
regulate land use and development. However, in the NT, the planning system is administered by 
the NT Government rather than local government. 

3.1.2 Introduction 

This chapter seeks to address the following questions. In the Southern Gulf catchments, what are 
the existing: 

•ecological systems
•demographic and economic profiles, land use, industries and infrastructure
•values, rights, interests and development objectives of Indigenous Peoples?


The chapter is structured as follows:

•Section 3.2 examines the ecological systems and assets of the Southern Gulf catchments,
including the key habitats and biota and their important interactions and connections.
•Section 3.3 examines the socio-economic profile of the Southern Gulf catchments, includingcurrent demographics, existing industries and infrastructure of relevance to water resourcedevelopment.
•Section 3.4 examines the Indigenous values, rights, interests and development objectives ofTraditional Owners from the Southern Gulf catchments, generated through a literature review ofjournal articles, grey literature and media articles.



3.2 Southern Gulf catchments and their environmental values 

This section provides an overview of the environmental values and freshwater, marine and 
terrestrial ecological assets found in the Southern Gulf catchments. Unless otherwise stated, the 
material in this section is based on findings described in the companion technical report on 
ecological assets (Merrin et al., 2024). 

The Southern Gulf catchments span an area of 108,200 km2, of which 21% lies in the NT and 79% 
lies in Queensland. They are composed of Settlement (17,600 km2), Nicholson (52,200 km2), 
Leichhardt (33,400 km2) and Morning Inlet (3,700 km2) catchments, and the Wellesley island 
groups (1,200 km2). Agricultural production is the largest land use in the catchments, mostly cattle 
grazing on native pastures (77%) (ABARES, 2022). Other land uses include recreational activities, 
tourism, traditional and commercial fisheries, mining and Indigenous uses. In addition, these 
catchments have important ecological and environmental values. Within these catchments and 
the surrounding marine environment are rich and important ecological assets, including species, 
ecological communities, habitats, and ecological processes and functions (see the conceptualised 
summary in Figure 3-2). The ecology of the Southern Gulf catchments is maintained by the flow 
regime in each catchment, shaped by the region’s wet-dry climate and complex geomorphology 
and topography and driven by seasonal rainfall, evapotranspiration and groundwater discharge. 



For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-2 Conceptual diagram of selected ecological assets of the Southern Gulf catchments 

Ecological assets include species of significance, species groups, important habitats and ecological processes. See 
Table 3-2 for a complete list of the fresh water–dependent, marine and terrestrial ecological assets considered in the 
Southern Gulf catchments. 

Biota icons: adapted from Integration and Application Network (2023) 

The Southern Gulf catchments have a highly seasonal climate with an extended dry season. 
Rainfall averages 602 mm/year with 94% of the rainfall falling in the wet season (McJannet et al., 
2023). The dominant vegetation types in the catchments are open eucalypt open woodlands, 
Melaleuca forests and woodlands, and tussock grasslands (Department of Climate Change‚ Energy‚ 














the Environment and Water, 2020). The Southern Gulf catchments have two major water storages: 
Lake Julius and Lake Moondarra. Both storages are located on the Leichhardt River and are listed 
in the Directory of Important Wetlands in Australia (DIWA). While the water in these two storages 
predominantly supplies urban, mining and industrial demand around Mount Isa and Cloncurry, the 
permanent water provides important dry-season refuge for waterbirds and supports a variety of 
freshwater fish species (Department of Agriculture‚ Water and the Environment, 2021a). 
During the wet season, flooding inundates significant parts of the downstream reaches of the 
catchments connecting wetlands to the river channel, inundating floodplains and driving a 
productivity boom. This flooding is particularly evident in the downstream parts of the 
catchments, including the floodplain wetlands, and extensive intertidal flats on the mainland 
coastline south of Bentinck and Sweers islands, where it delivers extensive discharges into the 
marine waters of the south-western Gulf of Carpentaria. 
While most rivers in the Southern Gulf catchments are ephemeral, the Gregory and O'Shannassy 
rivers and Lawn Hill Creek are perennial, being fed by groundwater from the Thorntonia Limestone 
(see Section 2.5.4). These perennial waterways provide critical refuge habitat for many aquatic 
species in this semi-arid environment. During the dry season, river flows are reduced and the 
streams in the catchment contract, resulting in series of instream waterholes that also provide 
critical habitat in the dry season. 
Protected, listed and significant areas of the Southern Gulf catchments 
The protected areas located in the Southern Gulf catchments include the UNESCO World 
Heritage-listed Australian Fossil Mammal Sites (Riversleigh), three Indigenous Protected Areas 
(IPAs) – Ganalanga-Mindibirrina, Nijinda Durlga and Thuwathu/Bujimulla – and Boodjamulla 
(encompassing Lawn Hill) and Finucane Island national parks and other conservation parks (Figure 
3-4). The Australian Fossil Mammal Sites (Riversleigh) is largely situated within the Boodjamulla 
National Park (Aboriginal Land). It is considered one of the richest and most extensive fossil 
deposits in the world. 
The Ganalanga-Mindibirrina IPA (NT) is located in the upper reach of the Nicholson River and 
covers over 1 million ha. The Nijinda Durlga IPA covers over 186,850 ha and includes habitat for 
marine turtles, dugongs, shorebirds and seabirds. The Thuwathu/Bujimulla IPA spans across the 
Wellesley Islands and includes over 1.6 million ha of marine area and over 120,000 ha of land. The 
area contains significant habitat for sea turtles, shorebirds and seabirds. It is also culturally 
significant, including having the largest collection of stone fish traps in the southern hemisphere 
(Australian Indigenous Australians Agency, 2023). 
Boodjamulla National Park (Aboriginal Land) includes sandstone ranges, Lawn Hill Gorge and the 
Australian Fossil Mammal Sites (Riversleigh) UNESCO World Heritage site. Lawn Hill Gorge is 
formed by Lawn Hill Creek, which is groundwater fed, as are the Gregory and O'Shannassy rivers. 
Lawn Hill Creek and Gregory River contain wet riverine forest and support a variety of plant 
species. Lawn Hill Creek supports freshwater turtles, including the Gulf snapping turtle (Elseya 
lavarackorum; listed as Endangered under the Environment Protection and Biodiversity 
Conservation Act 1999 (EPBC Act)) and more than 20 species of fish. Across the catchment, 
permanent water sources provide important refuge habitat for a broad variety of species 
(Queensland Department of Environment and Science, 2023a). 


Finucane Island National Park, a 7610 ha island within a river network, is located within the 
Southern Gulf Aggregation DIWA site. It includes estuarine wetlands, salt flats, mangroves and 
grasslands. The park provides important habitat for fish and waterbirds (Queensland Department 
of Environment and Science, 2023b). 

The Southern Gulf catchments contain 13 nationally significant wetlands listed in the DIWA: 
Bluebush Swamp, Buffalo Lake Aggregation, Forsyth Island Wetlands, Gregory River, Lake Julius, 
Lake Moondarra, Lawn Hill Gorge, Marless Lagoon Aggregation, Musselbrook Creek Aggregation, 
Nicholson Delta Aggregation, Southern Gulf Aggregation, Thorntonia Aggregation and Wentworth 
Aggregation (Figure 3-4) (Department of Agriculture‚ Water and the Environment, 2021a). These 
DIWA-listed wetlands include a variety of wetland types, ranging from estuarine wetlands with salt 
flats and saltmarshes to artificial lakes and spring-fed creeks and rivers. No wetlands listed under 
the Ramsar Convention on Wetlands of International Importance occur within the Southern Gulf 
catchments. 

In Queensland, statewide vegetation mapping classifies remnant vegetation communities as 
regional ecosystems and includes an assessment of the condition of the remnant vegetation with a 
biodiversity status (Queensland Department of Environment, Science and Innovation, 2024a). 
Regional ecosystems with a biodiversity status of endangered or of concern are shown on 
Figure 3-5. This data underpins the Vegetation Management Act 1999 and Planning Act 2016 (Qld) 
where applications for clearing for development are submitted. 




Figure 3-3 Estuarine crocodiles inhabit fresh and saltwater environments 

Photo: CSIRO – Nathan Dyer 




Ecology wetlands and protected areas map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-4 Location of protected areas and important wetlands within the Southern Gulf catchments Assessment 
area 

Includes management areas protected mainly for conservation through management intervention as defined by the 
International Union for Conservation of Nature (IUCN). 

Dataset: Department of Agriculture‚ Water and the Environment (2020a); Department of Agriculture‚ Water and the Environment (2020b) 
Department of the Environment and Energy (2010) 




Qld Regional ecosystem biodiversity status, map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\4_S_Gulf\1_GIS\1_Map_Docs\CR-S-519_RemVeg_Status_v2StandardColor.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-5 Regional ecosystem biodiversity status in the Queensland part of the Southern Gulf catchments 

Datasets: Department of Agriculture‚ Water and the Environment (2020b); Queensland Department of Environment, Science and Innovation 
(2024a) 




Important habitat types and values of the Southern Gulf catchments 

The freshwater sections of the Southern Gulf catchments provide diverse habitats, including 
persistent and ephemeral rivers, wetlands, floodplains and groundwater-dependent ecosystems 
(GDEs). The diversity and complexity of habitats, and the connections between habitats within a 
catchment, are vital for providing the range of habitats needed to support both aquatic and 
terrestrial biota (Schofield et al., 2018). 

In the wet season, flooding connects rivers to floodplains. The exchange of water between the 
river and the floodplain supports higher levels of primary and secondary productivity than is found 
in surrounding areas that are less frequently inundated (Pettit et al., 2011). Infiltration of water 
into the soil during the wet season and along persistent streams often enables riparian habitats to 
form an important interface between the aquatic and terrestrial environments. While riparian 
habitats often occupy a relatively small proportion of the catchment, they frequently have a 
higher species richness and abundance of individuals than surrounding habitats (Pettit et al., 2011; 
Xiang et al., 2016). 

In the dry season, biodiversity is supported by the perennial rivers and creeks, permanent lakes 
and inchannel waterholes. These water sources that persist through the dry season become 
increasingly important as the season progresses; they provide important refuge habitat for species 
and enable recolonisation into surrounding habitats upon the return of larger flows (Hermoso et 
al., 2013). Persistent waterholes provide habitat for water-dependent species, including fish, 
sawfish and turtles, as well as providing a source of water for other species more broadly within 
the landscape (McJannet et al., 2014; Waltham et al., 2013). 

The terrestrial habitats of northern Australia include a range of diverse and significant habitat 
types. While much of the tropics of northern Australia is savanna, eucalypt forest and grasslands, 
other habitats include riparian and floodplain communities and GDEs. Many of these are highly 
dependent upon fresh water supplied from rivers, and their persistence and condition can also be 
supported by groundwater discharges. 

Riparian and floodplain communities from the Queensland remnant vegetation regional 
ecosystem data with endangered and of concern biodiversity status are well represented in the 
Southern Gulf catchments (Figure 3-5). Areas where the dominant regional ecosystem is 
endangered (0.7% of the Queensland section of the Southern Gulf catchments, Table 3-1) are 
spread across riparian zones of the higher relief areas with associated seasonally wet areas nearby 
having endangered sub-dominant regional ecosystems (3.2%). Areas of the more frequently 
flooded floodplains of the larger rivers and creeks have dominant regional ecosystems classified as 
of concern (10.5%) with larger areas of the floodplain less frequently flooded with a biodiversity 
‘of concern’ on one or more of the subdominant regional ecosystems (12%) (Queensland 
Department of Environment, Science and Innovation, 2024a). 

 


Table 3-1 Categories of biodiversity status of the Queensland regional ecosystems 

CATEGORY 

DEFINITION 

SUBCLASS 

AREA OF THE 
QUEENSLAND PART OF 
THE SOUTHERN GULF 
CATCHMENTS 

(HA) 

PERCENTAGE OF THE 
QUEENSLAND PART OF 
THE SOUTHERN GULF 
CATCHMENTS 

(%) 

Endangered 

Remnant vegetation is less than 10% of its pre-
clearing extent across the bioregion; or 10–30% 
of its pre-clearing extent remains and the 
remnant vegetation is less than 10,000 ha. 

Dominant†

Sub- 
dominant‡ 

59,417 

271,745 

0.7 

3.2 

Of concern

Remnant vegetation is 10 to 30% of its pre-
clearing extent across the bioregion; or more 
than 30% of its pre-clearing extent remains and 
the remnant extent is less than 10,000 ha. 

Dominant† 

Sub- 
dominant‡

898,058 

1,025,883 

10.5 

12 



†‘Dominant’ subclass means that greater than 50% of the polygon contains the regional ecosystem mapping. 

‡‘Sub-dominant’ subclass means that less than 50% of the polygon contains the regional ecosystem mapping. 

GDEs occur across many parts of the Southern Gulf catchments and come in different forms, 
including aquatic, terrestrial and subterranean habitats. Aquatic GDEs contain springs and river 
sections that hold water throughout most dry seasons due to groundwater discharge. Aquatic 
GDEs are important for supporting aquatic life and fringing vegetation, and in the wet-dry tropics 
they provide critical refuge during periods of the late dry season (James et al., 2013). Vegetation 
occurring adjacent to the waterways in the Southern Gulf catchments relies on water from a range 
of sources (surface water, soil water, groundwater) which are seasonally dynamic and highly 
spatially variable. Water may be sourced from a combination of direct rainfall, bank recharge from 
instream flows, local floodplain recharge from surface water inundation during overbank flows, 
and/or shallow groundwater connected to intermediate or regional aquifer systems. Perennial 
floodplain vegetation often uses groundwater when it is within reach of the root network, 
particularly during the dry season or drought, but the origin of the groundwater used has only 
been infrequently investigated (e.g. Canham et al. (2021)). In some locations, vegetation may be 
sustained by water available in soils and so never use groundwater. In other locations, vegetation 
may use groundwater sourced from local alluvial recharge processes; alternatively, regional 
groundwater may be critical for maintaining vegetation condition. Subterranean aquatic 
ecosystems in the limestone that occur in the upper south-western region of the Southern Gulf 
catchments support subterranean fauna that depend on the presence of groundwater 
(e.g. troglofauna, which live in caves, and stygofauna, which live in groundwater systems). 

The marine and estuarine environments of the Southern Gulf catchments, including the mainland 
area adjacent to Mornington and Sweers islands, have extensive intertidal flats and estuarine 
communities, including mangroves, salt flats and seagrass habitats. These habitats are highly 
productive, have high cultural value and are often of national significance (Poiner et al., 1987). 
Seagrass beds in the nearby coastal Gulf of Carpentaria have high diversity, vigorous stands and 
provide an important food and habitat for dugongs, green turtles (Chelonia mydas) and prawns 
(Loneragan et al., 1997; Poiner et al., 1987). These near-coastal and estuary habitats support a 
major commercial barramundi fishery (Bayliss et al., 2014). Mud crabs (mainly Scylla serrata) are 
also harvested (Bayliss et al., 2014). 


Significant species and ecological communities of the Southern Gulf catchments 

A number of aquatic and terrestrial species occurring in the Southern Gulf catchments are 
currently listed as Critically endangered, Endangered or Vulnerable under the EPBC Act and by the 
NT Government’s wildlife classification system and the Queensland Government’s threatened 
species conservation system. These include freshwater or large tooth sawfish (Pristis pristis; 
Vulnerable, EPBC Act) and the Gulf snapping turtle (Elseya lavarackorum; Endangered, EPBC Act). 
The Southern Gulf catchments are important stopover habitat for migratory shorebird species 
listed under the EPBC Act, including the eastern curlew (Numenius madagascariensis; Critically 
endangered) and the Australian painted snipe (Rostratula australis; Endangered) (Atlas of Living 
Australia, 2021; Department of Agriculture‚ Water and the Environment, 2021b). 

While there are many plant species that fall into the endangered and of concern regional 
ecosystems from the Queensland remnant vegetation mapping, the regional ecosystem that is 
most common in the endangered dominant category in the Southern Gulf catchments is the 
Eucalyptus camaldulensis woodland on channels and levees (regional ecosystem (RE) class 1.3.7), a 
regional ecosystem of the riparian zone and an important seasonal water bird habitat also 
providing regional corridors for fauna. The most common regional ecosystem in the ‘of concern’ 
dominant category is the woodlands of the creek and river frontage (regional ecosystem (RE) class 
2.3.20) providing refuges for flora and fauna (Queensland Department of Environment, Science 
and Innovation, 2024a). Threatening processes for these two areas are the dry season impacts of 
high grazing pressure leading to habitat degradation and loss leaving areas prone to weed 
infestation. 

3.2.1 Potential threats in the Southern Gulf catchments 

Land use practices and ecology 

Northern Australia more broadly encompasses some of the last relatively undisturbed tropical 
riverine landscapes in the world with low levels of flow regulation and low development intensity 
(Pettit et al., 2017; Vörösmarty et al., 2010). Fishing in northern Australia is a valuable industry, 
and the waters of the Gulf of Carpentaria contribute significantly to the national catch of 
important species, including prawns, mud crabs and barramundi. Riparian vegetation 
characteristics of the Southern Gulf catchments are considered to not be affected by extensive 
clearing or development, although impacts that occur are often associated with stock and pest 
species (Department of Agriculture‚ Water and the Environment, 2021a). 

A range of economic enterprises, infrastructure and human impacts occur in the Southern Gulf 
catchments, and the nature and extent to which these have modified habitats and affected 
species of the Southern Gulf catchments varies. The study area includes the towns of Burketown 
and Doomadgee and the city of Mount Isa, which support tourism and mining and act as regional 
hubs for many of the cattle stations across the catchments. While a proportion of the catchments 
are under conservation reserves, the study area does face environmental threats, including the 
potential for further mining and tourism-related impacts at sensitive and vulnerable sites. 

One of the most significant environmental threats to remote regions across northern Australia is 
that of introduced plants and animals. In the Southern Gulf catchments, introduced animals 
include feral horses (Equus caballus), wild pig (Sus scrofa) and cane toads (Rhinella marina) 


(Department of Agriculture‚ Water and the Environment, 2021a; 2021b). Weeds of national 
significance in the aquatic systems of northern Australia include salvinia (Salvinia molesta) and 
rubber vine (Cryptostegia grandiflora) (Close et al., 2012). Weed species of interest in and around 
the Southern Gulf catchments include prickly acacia (Vachellia nilotica), buffel-grass (Cenchrus 
ciliaris), rubber vine and water hyacinth (Eichhornia crassipes) (Department of Agriculture‚ Water 
and the Environment, 2021b). 

Water resource development and ecology 

Impacts associated with water resource development include the following, which are described 
below: 

• flow regime change 
• altered longitudinal and lateral connectivity 
• habitat modification and loss 
• increased invasive and non-native species 
• synergistic and co-occurring processes. 


Flow regime change 

Water resource development, including water harvesting and creating instream structures for 
water retention, can influence the timing, quality and quantity of water that is provided by 
catchment runoff into the river system. The natural flow regime is important in supporting a broad 
range of environmental processes upon which species and habitat condition depend (Lear et al., 
2019; Poff et al., 1997). Flow conditions provide the physical habitat in streams and rivers, which 
determines biotic use and composition and to which life-history strategies are adapted. Flow 
enables movement and migration between habitats and exchange of nutrients and materials 
(Bunn and Arthington, 2002; Jardine et al., 2015). In a river system, the natural periods of both low 
and high flow (including no-flow events) are important to support the natural function of habitats, 
their ecological processes and the shaping of biotic communities (King et al., 2015). Through the 
attenuation of flows, water resource development can lead to impacts across significant distances 
downstream of the development, including into coastal and near-shore marine habitats (Broadley 
et al., 2020; Pollino et al., 2018). 

Altered longitudinal and lateral connectivity 

River flow facilitates the exchange of biota, materials, nutrients and carbon along the river and 
into the coastal areas (longitudinal connectivity), as well as between the river and the floodplain 
(lateral connectivity) (Pettit et al., 2017; Warfe et al., 2011). Physical barriers such as weirs, dams 
and causeways, or a reduction in the magnitude of flows (and the duration or frequency), can 
affect longitudinal and lateral connectivity, changing the rate or timing of exchanges (Crook et al., 
2015). These impacts can include changes in species’ migration and movement patterns as well as 
altered erosion processes and discharges of nutrients into rivers and coastal waters (Brodie and 
Mitchell, 2005). Seasonal patterns and rates of connection and disconnection caused by flood 
pulses are important for providing seasonal habitat and enabling movement of biota into new 
habitats and their return to refuge habitats during drier conditions (Crook et al., 2020). 


Habitat modification and loss 

Water resource development can cause direct loss of habitat. For example, artificially creating a 
lake (inundated) habitat behind an impoundment results in loss of terrestrial and stream habitat. 
Agricultural development converts existing habitat to more-intensive agriculture. Infrastructure, 
including roads and canals, can fragment terrestrial habitat or artificially connect aquatic habitats 
that had been historically separated. 

Increased invasive and non-native species 

Water resource development often homogenises flow and flow-related habitats, for example, 
through changed patterns resulting from capture and release of flows or creation of 
impoundments for storage and regulation. Invasive species are often at an advantage in such 
modified habitats (Bunn and Arthington, 2002). Modified landscapes, such as lakes or perennial 
streams that were previously ephemeral, can be a pathway for introduction of, and support the 
incidental, accidental or deliberate establishment of, non-native species, including pest plants and 
fish (Bunn and Arthington, 2002; Close et al., 2012; Ebner et al., 2020). Increased human activity 
can increase the risk of invasive species being introduced. 

Synergistic and co-occurring processes both local and global 

Along with water resource development comes a range of other pressures and threats, including 
increases in fishing; vehicles; habitat fragmentation; pesticides, fertilisers and other chemicals; 
erosion; degradation due to increased stock pressure; and changed fire regimes, climate change 
and other human disturbances, both direct and indirect. Some of these pressures are the direct 
result of changes in land use associated with or accompanying water resource development. Other 
pressures may occur regionally or globally and act synergistically with water resource 
development and agricultural development to increase the risk to species and their habitats (Craig 
et al., 2017; Pettit et al., 2012). 

To describe the ecology of the Southern Gulf catchments and discuss the likely impacts of future 
water resource development on this system, a suite of ecological assets has been selected 
(Table 3-2). Assets are classified as species, species groups or habitats. They can be considered as 
either partially or fully dependent on fresh water, or terrestrial or marine dependent upon 
freshwater flows (or services provided by freshwater flows). This chapter considers a key subset of 
assets, as listed in Table 3-2. More information on the ecological assets of the Southern Gulf 
catchments and their distribution is available in the companion technical report on ecological 
assets (Merrin et al., 2024). Chapter 7 presents results of the modelling and analysis to explore the 
potential of change to these assets as a consequence of water resource development. 


Table 3-2 Freshwater, marine and terrestrial ecological assets with freshwater flow dependences in the Southern 
Gulf catchments 

An asterisk (*) represents an asset outlined in this report. All listed species, species groups and habitat assets are 
detailed in the companion technical report on ecological assets (Merrin et al., 2024). 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au.
3.2.2 Ecological assets in the Southern Gulf catchments 

Northern Australia’s rivers, floodplains and coastal regions contain high biodiversity, including at 
least 170 fish species, 150 waterbird species, 30 aquatic and semi-aquatic reptile species, 
60 amphibian species and 100 macroinvertebrate families (van Dam et al., 2008). The ecology of 
the freshwater systems is supported by, and adapted to, the highly seasonal flow regimes of the 
wet-dry tropics. Water resource development and climate change threaten to affect these 
habitats and species. This section provides a synthesis of the prioritised assets relevant to the 
Southern Gulf catchments for the purpose of understanding potential ecological outcomes of flow 
regime change. Table 3-2 lists the assets evaluated in the Southern Gulf catchments ecology 
activity. 


Floodplain wetlands 

Wetlands in the wet-dry tropics of Australia have great conservation value (Finlayson et al., 1999) 
and are one of the most diverse aquatic ecosystems in Australia (Douglas et al., 2005). Wetlands 
provide permanent, temporary or refugia habitat for both local and migratory waterbirds (van 
Dam et al., 2008) (Figure 3-6), spawning grounds and nurseries for floodplain-dependent fish 
(Ward and Stanford, 1995), and habitat for many other aquatic and riparian species (van Dam et 
al., 2008). Floodplain wetlands are an important source of nutrients and organic carbon, driving 
primary and secondary productivity (Junk et al., 1989; Nielsen et al., 2015). Wetlands also provide 
a range of additional ecosystem services, including water quality improvement, carbon 
sequestration and flood mitigation (Mitsch et al., 2015). 

 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au.
Figure 3-6 Brolgas flying into the sunset at Lake Moondarra 

Photo: CSIRO 

Hydrological regimes are fundamental to sustaining the ecological characteristics of rivers and 
their associated floodplains (Pettit et al., 2017). In the wet-dry tropics of northern Australia, the 
ecology of wetlands is often highly dependent on the seasonal rainfall–runoff pattern and the 
associated low and high flows from rivers (Pidgeon and Humphrey, 1999; Warfe et al., 2011). 
These flows are important drivers of floodplain wetland ecosystem structure and processes (Close 
et al., 2012; Warfe et al., 2011). Changes to these flow characteristics are likely to have a 
significant impact on the aquatic biota (Close et al., 2012). The timing, duration, extent and 
magnitude of wetland inundation have the greatest impact on the ecological values, which include 
species diversity, productivity and habitat structure (Close et al., 2015). 

Under the Ramsar Convention (Ramsar Convention Secretariat, 2004), wetlands are defined as: 

areas of marsh, fen, peatland or water, whether natural or artificial, permanent or 
temporary, with water that is static or flowing, fresh, brackish or salt, including areas of 
marine water the depth of which at low tide does not exceed six metres. 


The NT Government defines wetlands as including coastal saltmarshes, mangrove swamps, 
freshwater lakes and swamps, floodplains, freshwater ponds, springs and saline lakes, that can be 
permanent, seasonal or intermittent, and can be natural or artificial (NT Government, 2020). For 
delineation, this Assessment considers areas within the river channel to be inchannel waterholes 
rather than wetlands (see Merrin et al. (2024)). Similarly, marine or saline habitats including 
mangroves and coastal saltmarshes (salt flats) are also treated as separate assets in this project 
(see Saltpans and salt flats below and Merrin et al. (2024)). 

The Southern Gulf catchments have 13 nationally significant wetlands listed under the DIWA 
(Table 3-3 and Figure 3-7) (Department of Agriculture‚ Water and the Environment, 2021a). There 
are no Ramsar-listed wetlands within the Southern Gulf catchments. 

Table 3-3 Nationally important wetlands in the Southern Gulf catchments 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au. 
The Wentworth Aggregation is found in the Settlement Creek catchment (Figure 3-7) and covers 
an area of 82,306 ha (Department of Agriculture‚ Water and the Environment, 2021a). It contains 
the full range of wetland types (estuarine, lacustrine (lake), palustrine (marshes and swamps) and 
riverine) and is considered to have high wilderness value due to its remoteness. The main habitat 
types are estuarine salt flats and saltmarshes (55.6% of the wetland area); coastal and sub-coastal 
non-floodplain tree swamp – Melaleuca spp. and Eucalyptus spp. (13.5% of the wetland area); 
coastal and sub-coastal floodplain grass, sedge, herb swamp (7.2% of the wetland area); and 
estuarine – mangroves and related tree communities (6.7% of the wetland area) (Queensland 
Department of Environment and Science, 2022). It is considered an important wetland for 
waterbirds (Department of Agriculture‚ Water and the Environment, 2021a). 

The Marless Lagoon Aggregation spans the Settlement Creek and Nicholson River catchments 
(Figure 3-7) and has an area of 166,948 ha (Department of Agriculture‚ Water and the 
Environment, 2021a). It has extensive palustrine wetlands (97.6% of the wetland area) in which 
the dominant habitat type is coastal and sub-coastal non-floodplain tree swamp – Melaleuca spp. 


and Eucalyptus spp. (97.3% of the wetland area) (Queensland Department of Environment and 
Science, 2022). 

 

For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-7 Land subject to inundation (potential floodplain wetlands) and important wetlands in the Southern Gulf 
catchments 

Dataset: Geoscience Australia (2017); Department of the Environment and Energy (2010) 

 


Bluebush Swamp is located in the Nicholson catchment (Figure 3-7) and is 879 ha (Department of 
Agriculture‚ Water and the Environment, 2021a). It is a scrub–shrub wetland with Acacia 
stenophylla as the dominant species, and it has areas of shallow, open water. Bluebush Swamp 
provides habitat for waterbirds in the late wet season and in autumn and spring (Department of 
Agriculture‚ Water and the Environment, 2021a). 

Lawn Hill Gorge is located within Boodjamulla National Park (Aboriginal Land) in the Nicholson 
catchment (Figure 3-7) and has an area of 1133 ha (Department of Agriculture‚ Water and the 
Environment, 2021a). Prior to being gazetted as a national park, it was extensively grazed, and 
feral pigs and other invasive animals continue to affect the area. Various recreational activities are 
available within the national park, although visitor numbers are controlled. Indigenous usage of 
the area dates back between 17,000 and 30,000 years (Department of Agriculture‚ Water and the 
Environment, 2021a). The gorge itself is located on Lawn Hill Creek, which is fed by groundwater 
from the Thorntonia Limestone and also receives wet-season flushes (Department of Agriculture‚ 
Water and the Environment, 2021a; Queensland Department of Environment and Science, 2023a). 

Musselbrook Creek Aggregation is located in the Nicholson catchment (Figure 3-7) and has an area 
of 45,114 ha (Department of Agriculture‚ Water and the Environment, 2021a). The dominant 
habitat types are coastal and sub-coastal floodplain tree swamp – Melaleuca spp. and 
Eucalyptus spp. (34.6% of the wetland area), arid and semi-arid tree swamp (floodplain) (32.8% of 
the wetland area) and river (27.6% of the wetland area) (Queensland Department of Environment 
and Science, 2022). The area has been extensively grazed by cattle and feral horses (Department 
of Agriculture‚ Water and the Environment, 2021a). 

Nicholson Delta Aggregation is located in the Nicholson catchment (Figure 3-7) and has an area of 
63,646 ha (Department of Agriculture‚ Water and the Environment, 2021a). This aggregation has a 
fresh water – saltwater gradient, as estuarine waters flood the salt flats and tidal channels, 
particularly during the dry season. There is also a series of freshwater wetlands (Department of 
Agriculture‚ Water and the Environment, 2021a). The main habitat is estuarine – salt flats and 
saltmarshes (40.8% of the wetland area) and river (31.1% of the wetland area) (Queensland 
Department of Environment and Science, 2022). The wetlands in this aggregation are a mix of 
permanent, semi-permanent and seasonal wetlands, and they provide refugia habitat for 
waterbirds in the dry season (Department of Agriculture‚ Water and the Environment, 2021a). 

Thorntonia Aggregation is located in the catchment of the Gregory River (Figure 3-7) and has an 
area of 298,629 ha (Department of Agriculture‚ Water and the Environment, 2021a). It is partly 
within the Boodjamulla National Park (Aboriginal Land) and contains the internationally significant 
Riversleigh fossil field. It has deep permanent channels which are spring fed and shallower 
seasonal channels. The perennial channels provide refugia habitat in the dry season (Department 
of Agriculture‚ Water and the Environment, 2021a). 

The Gregory River DIWA site spans the Nicholson and Leichhardt catchments (Figure 3-7) and has 
an area of 26,630 ha (Department of Agriculture‚ Water and the Environment, 2021a). It is the 
largest perennial river in semi-arid and arid Queensland that is spring fed with additional flow 
from runoff. The area is used for recreational purposes, including camping, canoeing and fishing, 
and has had extensive cattle grazing. Freshwater crocodiles (Crocodylus johnstoni) are very 
common (Department of Agriculture‚ Water and the Environment, 2021a). 


Lake Julius is an artificial lake located in the Leichhardt catchment (Figure 3-7). Lake Julius is on the 
Leichhardt River and has a surface area of 1255 ha at full supply. It was created when the Julius 
Dam was completed in 1976 and provides backup supplies to Lake Moondarra as well as supplying 
water to Cloncurry Council and mines in the North West Minerals Province (Department of 
Agriculture‚ Water and the Environment, 2021a). The lake is used for recreational purposes, 
including boating and fishing, and the land surrounding the lake is used to graze cattle. As a 
permanent lake, it provides important habitat for waterbirds during the dry season. It also 
supports a variety of freshwater fish, red-clawed crayfish (Cherax quadricarinatus) and freshwater 
crocodiles (Department of Agriculture‚ Water and the Environment, 2021a). 

Lake Moondarra (Figure 3-7) is an artificial lake, completed in 1957 and raised in 1971, of 2190 ha 
and located just outside the town of Mount Isa in the Leichhardt catchment (Figure 3-7). Situated 
on the Leichhardt River, it is upstream of Lake Julius. As a permanent water body, it provides 
refugia habitat for waterbirds and is considered an important recreation area, allowing for both 
boating and fishing. Cattle grazing is extensive, often resulting in damage at the water’s edge. 
Seasonal turbidity is an issue (Department of Agriculture‚ Water and the Environment, 2021a). 

Buffalo Lake Aggregation has an area of 1911 ha and is located in the Morning Inlet catchment 
(Figure 3-7) (Department of Agriculture‚ Water and the Environment, 2021a). The lake is shallow 
(<1 m depth) and ephemeral, flooding in extreme wet seasons and drying out completely most dry 
seasons. It is also occasionally flooded by tidal surges (Department of Agriculture‚ Water and the 
Environment, 2021a). The dominant habitats are coastal and sub-coastal floodplain lakes (69.0% of 
the wetland area) and coastal and sub-coastal floodplain grass, sedge, herb swamps (24.3% of the 
wetland area) (Queensland Department of Environment and Science, 2022). The lake habitat 
provides important habitat for waterbirds, including migratory species. The area has been 
extensively grazed (Department of Agriculture‚ Water and the Environment, 2021a). 

Southern Gulf Aggregation is the largest continuous estuarine wetland in Australia at 545,577 ha, 
and it spans all four of the Assessment catchments (Figure 3-7) (Department of Agriculture‚ Water 
and the Environment, 2021a). Dominated by estuarine – salt flats and saltmarshes (77.3% of the 
wetland area) and estuarine – mangroves and related tree communities (20.4% of the wetland 
area) (Queensland Department of Environment and Science, 2022), the area is governed by 
estuarine tides, and during the wet season, freshwater flooding (Department of Agriculture‚ Water 
and the Environment, 2021a). The wetlands located along the inland edges of the aggregation are 
all seasonal and are brackish. The area is considered one of the most important shorebirds sites in 
Australia (Department of Agriculture‚ Water and the Environment, 2021a). 

Forsyth Island Wetlands are located on Forsyth Island, about 10 km off the coast of Bayley Point. It 
is an estuarine wetland with important seagrass habitats in Government Bay (Department of 
Agriculture‚ Water and the Environment, 2021a). The habitat consists of estuarine – salt flats and 
saltmarshes (60.9% of the wetland area) and estuarine – mangroves and related tree communities 
(39.1% of the wetland area) (Queensland Department of Environment and Science, 2022). The 
island itself is an Indigenous reserve, with the area, including the surrounding waters, used for 
fishing and hunting (Department of Agriculture‚ Water and the Environment, 2021a). 

Significant parts of the floodplain areas within the Southern Gulf catchments are already 
incorporated into the existing 13 nationally significant wetlands (see land subject to inundation 
Figure 3-7). There is additional floodplain on Musselbrook Creek, extending beyond the 


Musselbrook Creek Aggregation. There is also additional floodplain near the Wentworth 
Aggregation (

Saltpans and salt flats 

Saltpans and salt flats are intertidal areas that are devoid of marine plants and are located 
between mangroves and saltmarsh meadows. Saltmarshes (Figure 3-8) occur in the supra-littoral 
zones, which are inundated only infrequently by the tide and where subsequent water 
evaporation leaves behind expanses of minerals and salts (Cotin et al., 2011). Inundation of 
saltpans mostly occurs during the annual wet season when large tides and rainfall surface runoff 
ponds as shallow wetted areas within the saltpans and shallow tidal-cut gutters that intersect 
them. Despite their infrequent inundation, saltpans provide habitat for some estuarine fish, such 
as barramundi (Russell and Garrett, 1983) and metapenaeid shrimps (Bayliss et al., 2014) during 
periods when the tide covers these habitats. 



Photo of saltpan.
For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au.
Figure 3-8 This saltpan area in northern Australia is typical in being located between mangrove and saltmarsh areas 

Photo: Nathan Waltham 

In northern Australia, saltpan sediments are infused with dormant algae that remain inactive in a 
desiccated state during the dry season (most of the year). However, during overbank inundation 
from flooded rivers or extensive rainfall, the saltpan soil algae become active and photosynthesise, 
increasing nutrient contribution to the ecosystem (Burford et al., 2016). After several days, active 
algal growth occurs, and carbon, nitrogen and phosphorous compounds are produced. Estimates 
suggest that saltpans can contribute up to an extra 13% of ecosystem primary productivity 
depending on the extend of saltpan inundation during the wet season (Burford et al., 2016). 
Saltpans would be most productive during high-level overbank flood flows. 


The inundation of saltpans expands the habitat available to estuarine benthic fish and crustaceans 
that can tolerate euryhaline conditions. In northern Australia, coastal saltpans can extend tens to 
hundreds of square kilometres. They provide habitat for a range of benthic fauna (Dias et al., 
2014), which are an important food source for high-order consumers, including shorebird species 
that use saltpans as resting and/or feeding areas during their migration, which can include long 
flights to Asia (Cotin et al., 2011; Lei et al., 2018; Rocha et al., 2017). The extent of saltpans in 
Australia is unknown, though they are common and extensive in more arid coastal areas, most 
notably in northern Australia (Duke et al., 2019). The northern Australian coastline extends for 
thousands of kilometres and is relatively pristine; low beach profiles backed by extensive saltpans, 
possibly 5 to 10 km inland, are characteristic of hundreds of kilometres of coastline (Short, 2022). 
Despite limited tidal exchange, saltpans provide important habitat resources for migratory birds 
that access these areas for feeding and shelter (Lei et al., 2018). In addition, saltpans provide 
erosion and sediment accumulation opportunities in estuaries as well as carbon sequestration 
services. 

Saltpans in the Southern Gulf estuaries are extensive and located behind tide-dominated beaches 
(Figure 3-10) (Short, 2020). They are mostly restricted to a tidal inundation area on the landward 
side of the mangroves that line the main river channel, but they also occur adjacent to Buffalo and 
Sweet swamps. The spatial data presented illustrate the extent of saltpans in these catchments, 
but the extent was presumably increased as part of the wide-scale dieback of mangroves in the 
Gulf of Carpentaria between late 2015 and early 2016 (Duke et al., 2017). There has been no 
targeted scientific survey of fish and crustacean communities over the saltpans of the Southern 
Gulf catchments marine region, presumably because they are located so high in the intertidal zone 
and are only infrequently covered with tidal water. Also, the catchments are very remote, which 
leads to difficulties with access and sampling. 

 


Figure 3-9 Australian bustards are common in grasslands and woodlands across northern Australia 

Photo: CSIRO – Nathan Dyer 


 

Saltpans, map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\7_Ecology\4_S_Gulf\1_GIS\1_Map_docs\Ec-S-506_CR_Salt_Flats_v10.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-10 Location of saltpans in the Southern Gulf catchments marine region 

Data source: Geoscience Australia (2017) 

 


Sawfish (Pristis and Anoxypristis spp.) 

Sawfish belong to the order Pristiformes. They are characterised by a distinctive tooth-lined 
rostrum or ‘saw’. As adults, sawfish can attain very large sizes, ranging from 5 to 7 m in total 
length. They are widely distributed in northern Australian marine waters, although they are not 
necessarily abundant (Last and Stevens, 2008; Morgan, 2011; Stevens et al., 2009). These species 
can migrate at landscape and oceanic scales through their life cycle. Inshore waters, including bays 
and estuaries, are important nursery grounds for neonates and juvenile sawfish up until about 4 to 
6 years of age (Morgan, 2011; Morgan et al., 2017; Peverell, 2005). Sawfish adults primarily inhabit 
tropical and subtropical coastal marine waters (Dulvy et al., 2016; Last and Stevens, 2008). 

Globally, sawfish are considered one of the most threatened marine taxa (Dulvy et al., 2016). Four 
species of sawfish occur in Australian waters, all listed as being of conservation significance at 
both national and international levels. The freshwater or large tooth sawfish (Pristis pristis), the 
green sawfish (P. zijsron) and the dwarf sawfish (P. clavata) are all listed as Vulnerable under the 
EPBC Act. The narrow sawfish (Anoxypristis cuspidata) is listed as Migratory under the EPBC Act, 
and because it is also listed in Appendix I and II under the Convention on the Conservation of 
Migratory Species of Wild Animals (Bonn Convention), it has similar protection status under the 
EPBC Act. Additionally, sawfish hold significant cultural and spiritual relevance to Indigenous 
Australians (Ebner et al., 2016). 

Sawfish are vulnerable to multiple threats, partly due to their morphology (the shape of their 
rostra) and behaviour and partly due to their life-history characteristics: long lives, slow growth 
and low reproductive rates, late maturation, relatively low abundance and high specificity of 
different habitats in different life stages (Peverell, 2005; Phillips et al., 2017; Stevens et al., 2009). 
Their habitats often overlap with coastal fisheries, making them highly susceptible to capture in 
gill-net and trawl fisheries and recreational fishing (because of the shape of their rostra). 

Sawfish rostra have been collected as trophies for decades (McDavitt, 1996), and there is a 
growing demand for live sawfish for display in public aquaria (Buckley et al., 2020; Compagno et 
al., 2006). Recent decades have seen high fishing mortality (Fry et al., 2021). Other pressures 
include cumulative impacts from climate change, habitat loss, artificial passage barriers and 
declining water quality that may have a significant impact on the movements of sawfish between 
freshwater and estuarine environments. 

The Gulf of Carpentaria is a haven ecosystem for the four recognised species of sawfish found in 
Australia, with observations occurring across the study area. Despite regional population declines 
due to fishing mortality over the past 50 years, northern Australia has viable populations of 
sawfish in contrast to sawfish populations elsewhere in Indo-Pacific region waters. 

Catfish (order Siluriformes) 

Catfish are a highly diverse group that inhabit both inland and coastal waters. The group includes 
freshwater species, marine species, and some that move between the river and the estuary (Pusey 
et al., 2020). Catfish in northern Australia belong to two families: Plotosidae (19 species in total) 
and Ariidae (17 species). Plotosidae are found in the Eastern Pacific and Indian Ocean and their 
tributary rivers, whereas Ariidae are a global family found in both freshwater and marine habitats. 

Most catfish are bottom-feeding omnivores. They feed on algae, submerged macrophytes, 
invertebrates and smaller fish. Species within the Ariidae are slow growing and generally large 


bodied. The family is notable for its reproductive traits: it has the largest eggs of any teleost group 
(>10 mm), and males exhibit strong parental care behaviour, incubating the eggs and developing 
the young in the mouth for up to 5 weeks (Pusey et al., 2004). Because of the tendency to feed 
opportunistically, ariid catfish can be very competitive, consuming a variety and large volumes of 
food. Thus, they can make up a lot of biomass in a catchment (Crook et al., 2020). 

The key plotosid species are reasonably tolerant of high temperature and low dissolved oxygen 
levels, but fish kills at very low dissolved oxygen levels have been reported (Bishop, 1980). The key 
threat to the two dominant Neosilurus species is potential flow barriers. Plotosidae need high 
flows to trigger spawning migration, and they require a barrier-free passage to spawning grounds 
in the headwater streams. While not as important as barramundi or sooty grunters (Hephaestus 
fuliginosus), the fork-tailed catfish (Neoarius graeffei) has considerable importance as a 
subsistence fish for Indigenous communities (Finn and Jackson, 2011; Jackson et al., 2011). The 
modelled potential distribution of the fork-tailed catfish is provided in Figure 3-12. 

The Southern Gulf catchments support catfish from both families with seven species of Ariidae and 
four species of Plotosidae. The ariid catfish include Sciades leptaspis, Amissidens hainesi, 
Hexanematichthys mastersi, Nemapteryx armiger, Plicofollis argyropleuron, Neoarius berneyi, 
Neoarius graeffei, Neoarius midgleyi, Neosilurus ater, Neosilurus hyrtlii, Porochilus argenteus and 
Sciades paucus. The larger-bodied ariid catfish like N. graeffei, N. berneyi and S. paucus are mainly 
found on the main stems of the Leichhardt, Gregory and Nicholson rivers. The usually smaller-
bodied Neosilurus species are mainly found in smaller tributaries. 

 


Figure 3-11 The O’Shannassy River – one of the northern Australian rivers where catfish are found 

Photo: CSIRO – Nathan Dyer 




Catfish distribution, map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-12 Modelled potential species distribution for fork-tailed catfish (Neoarius graeffei) in the Southern Gulf 
catchments 

Probability of occurrence is based upon a general linear model. Observation locations of other catfish species is 
provided in Merrin et al. (2024). 




Swimming, grazing and diving waterbirds 

The swimmers, grazers and divers group comprises species with a relatively high level of 
dependence on semi-open, open and deeper water environments. These species commonly swim 
when foraging (including diving, filtering, dabbling and grazing) or when taking refuge. In northern 
Australia, this group comprises 49 species from 11 families, including ducks, geese, swans, grebes, 
pelicans, darters, cormorants, shags, swamphens, gulls, terns, noddies and jacanas. This group can 
be further broken down into the subgroups: 

• diving swimmers – for example, cormorants, pelicans, grebes 
• aerial divers – for example, terns, gulls, noddies 
• grazing swimmers – for example, swans, coots, swamphens, ducks, geese. 


These species breed in Australia and may be sedentary, nomadic, migratory or partially migratory. 
Nesting generally occurs seasonally, usually in dense vegetation such as emergent macrophytes, 
trees and shrubs (Garnett et al., 2015). Nests are usually independent or semi-colonial, and while 
breeding is usually seasonal, it can be stimulated by flooding or large rainfall events (Kingsford and 
Norman, 2002). Species diets may be piscivorous, omnivorous or herbivorous (Barker and 
Vestjens, 1990). Changes in water depth, water extent or water duration can expose nests to 
predation or drowning, or reduce food availability, resulting in nest failure (McGinness, 2016; 
Poiani, 2006). 

The magpie goose (Anseranas semipalmata) (Figure 3-13) is one example of the swimmers, grazers 
and divers group, and while it is an iconic species in northern Australia, it is also the source of 
some conflict with humans when resources are limited (Corriveau et al., 2022; Frith and Davies, 
1961; Traill et al., 2010). The magpie goose is an ancient and unique species of particular 
importance to Indigenous Peoples, providing eggs, meat and feathers. This species feeds on 
aquatic vegetation and often nests colonially (Marchant and Higgins, 1990). While currently 
abundant in northern Australia, wild magpie goose populations have largely disappeared from 
southern Australia due to human-driven change such as habitat destruction and hunting (Nye et 
al., 2007). Climate change is likely to enhance the impacts of such changes on magpie geese in 
northern Australia (Poiani, 2006; Traill et al., 2009). 


 

Photo of magpie goose.
For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au.
Figure 3-13 Magpie goose perched on a fallen tree branch 

Magpie geese are a representative species of the swimmers, grazers and divers group. 

Photo: CSIRO 

3.2.3 Environmental protection 

A number of aquatic and terrestrial species in the Southern Gulf catchments are currently listed as 
Critically endangered, Endangered or Vulnerable under the EPBC Act, and by the wildlife 
classification systems of the NT and Queensland governments, which are based on the 
International Union for Conservation of Nature (IUCN) Red List of Threatened Species 
(Figure 3-14). 

If a proposed development is predicted to have a significant impact on a matter of national 
environmental significance (e.g. populations of a nationally listed species, communities, migratory 
species or wetlands of importance), it requires approval to proceed under the EPBC Act 
(Table 3-4). This approval is required irrespective of local government policies. The Australian 
Government Protected Matters Search Tool lists approximately 40 Threatened species for the 
Southern Gulf catchments, four of which are listed as Critically endangered. Also listed are 64 
migratory species. 




EPBC species, map 
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-14 Distribution of species listed under the Environment Protection and Biodiversity Conservation Act 1999 
and by the NT and Queensland governments in the Southern Gulf catchments 

Datasets: Department of Environment Parks and Water Security (2019); Department of Environment and Science (2023) WildNet; Department of 
the Environment and Energy (2010); Atlas of Living Australia (2023 a,b) 


Table 3-4 Definition of threatened categories under the Commonwealth Environment Protection and Biodiversity 
Conservation Act 1999, the NT wildlife classification system, and the Queensland Nature Conservation Act 1992 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
†The NT wildlife classification categories are based on the IUCN Red List categories and criteria. An extract of each category is presented here. For 
the full definition see https://nt.gov.au/__data/assets/pdf_file/0010/192538/red-list-guidelines.pdf. 




3.3 Demographic and economic profile 

3.3.1 Introduction 

This section describes the current social and economic characteristics primarily of the Queensland 
portion of the Southern Gulf catchments in terms of the demographics of local communities 
(Section 3.3.2), current industries and land use (Section 3.3.3), and existing infrastructure of 
transport networks, supply chains, utilities and community infrastructure (Section 3.3.4). Together 
these characteristics describe the built and human resources that would serve as the foundation 
upon which any new development in the Southern Gulf catchments would be built. 

Unless otherwise stated, the material in this section is based on findings described in the 
companion technical report on agricultural viability and social economics (Webster et al., 2024a). 
For specific details related to the NT context, readers are directed to consult the Victoria River 
Water Resource Assessment technical report on agricultural viability and socio-economics 
(Webster et al., 2024b) and the Roper River Water Resource Assessment technical report on 
agricultural viability and socio-economics (Stokes et al., 2023). 

3.3.2 Demographics 

The Southern Gulf catchments comprise four mainland river catchments (Settlement, Nicholson, 
Leichhardt and Morning Inlet) plus the larger islands of the Mornington Island ‘catchment’ in the 
Gulf of Carpentaria. The study area falls mainly within Queensland (79%), but the western part of 
the study area falls within the NT (21%). Within Queensland, the catchments comprise the entire 
Mornington, Doomadgee and Burke local government areas together with around half of the 
Mount Isa local government area and smaller parts of the adjacent local government areas of 
Carpentaria and Cloncurry. Within the NT, the catchments comprise parts of Barkly and Roper 
local government areas. At the state and territory level, the catchments include part of the 
electoral division of Traeger in Queensland and a small part of the Barkly electoral division within 
the NT. At the federal level, the catchments form part of the Division of Kennedy in Queensland 
and part of the Division of Lingiari in the NT. 

The population density of the Southern Gulf catchments is low at one person per 4.8 km2, which is 
about one-fourteenth that of Queensland and one-sixteenth that of Australia as a whole. The 
Assessment area contains one significant urban area (population >10,000 people): Mount Isa, a 
city of over 18,000 residents, was developed to support the mining of the extensive deposits in the 
surrounding area (particularly for lead, silver, copper and zinc). There are also a number of small 
towns and communities within the catchments, including Burketown and Doomadgee, and on the 
Wellesley Islands. Of these smaller settlements, only Doomadgee (population 1387 as at the 2021 
Census) has a population greater than 1000. The nearest major cities and population centres are 
the cities of Townsville and Cairns, respectively, approximately 1000 and 1100 km from Mount Isa. 
The Queensland capital city of Brisbane is approximately 1925 km from Mount Isa. 

The demographic profile of the catchments, based on data from the 2021, 2016, 2011 and 2006 
censuses, is shown in Table 3-5. The Australian Bureau of Statistics (ABS) reports statistics by 
defined statistical geographic regions (such as the nested hierarchy of statistical areas), but none 
of those regions closely approximates the Southern Gulf catchments. Instead, data are shown for: 


(i)Carpentaria (ABS Statistical Area Level 2 (SA2) region 315021404), being the single region thatencompasses the largest geographic area within the boundaries of the catchments (

Table 3-5 Major demographic indicators for the Southern Gulf catchments 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
†Weighted averages of scores for SA2 regions falling wholly or partially within the boundaries of the catchments. 
Sources: ABS (2006, 2011, 2016, 2021a) Census data 


 

ABS Statistical area for analysis map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-15 Boundaries of the Australian Bureau of Statistics Statistical Area Level 2 (SA2) regions used for 
demographic data in this analysis 

Inset shows the red square on the main map. 

Residents of the Southern Gulf catchments tend to be younger and more likely to identify as 
Indigenous than the typical resident of Queensland and of Australia as a whole. Incomes differ 
from the national and state mean, being higher than the state and national averages in Mount Isa 
but lower in the remainder of the study area. 

The people in the Southern Gulf catchments are predominantly younger (median age around 31) 
than is typical for Queensland and the country as a whole (median age around 38); however, the 
trend from 2011 and 2016 to 2021 suggests that the median age of the Southern Gulf catchments 
is slightly increasing. The population contains a much larger proportion of Indigenous Peoples 
(27.3%) than Queensland (4.6%) and the country overall (3.2%). The proportion of Indigenous 
Peoples varies across the study area: the Mount Isa SA2 region has a much smaller proportion 
than the remainder of the catchments, although at 21.4% Mount Isa is higher than that for 
Queensland and Australia. Beyond Mount Isa, the proportion of Indigenous Peoples within the 
population exceeds 60%. 

The heterogeneity of the Assessment area is most clearly demonstrated when focusing on 
incomes. The median weekly household income for the Mount Isa SA2 region ($2236) is 
substantially above that for Queensland ($1675) and Australia ($1746). In contrast, incomes for 
the remainder of the study area are substantially lower with median weekly income in the 
Carpentaria SA2 region being only $1279. A similar pattern is observed for households on low 
incomes. Excluding Mount Isa, the proportion of households on low incomes (i.e. less than 
$650/week) in the Carpentaria SA2 region was far higher, and the proportion on high incomes 


(more than $3000/week) far lower, than the proportion for Queensland and for the country as a 
whole. The opposite applies to the Mount Isa SA2 region. 

The Socio-Economic Indexes for Areas (SEIFA) metrics are presented in Table 3-6. The Southern 
Gulf catchments fall below the national mean for each metric. The remote Carpentaria SA2 region, 
which comprises a large geographic area of the study area, is classified within the first decile for 
each index, indicating the region is scoring below 90% of the rest of the country on each of the 
measures. However, the Mount Isa SA2 region, where most of the population live, scores in the 
2nd to 4th decile, depending on the specific index. Overall, weighted by population, the 
catchments are in the 2nd decile for the Index of Economic Resources (IER), the 3rd decile for 
Index of Education and Occupation (IEO), and the 4th decile for the remaining indices. Thus, while 
the level of disadvantage varies across the catchments, the different components and overall 
scores are all disadvantaged compared to the mean for Australia as a whole. 

Table 3-6 Socio-Economic Indexes for Areas (SEIFA) scores of relative socio-economic advantage for the Southern 
Gulf catchments 

Scores are relativised to a national mean of 1000, with higher scores indicating greater advantage. 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
†Weighted averages of scores for SA2 regions falling wholly or partially within the boundaries of the catchments. 
§Based on both the incidence of advantage and disadvantage. 
*Based purely on indicators of disadvantage. 
Source: ABS (2023) 

3.3.3 Current industries and land use 

Employment 

The economic structure of the combined Southern Gulf catchments differs from that of 
Queensland and Australia as a whole in having lower unemployment rates and a higher proportion 
of the adult population (aged 15 and older) within the labour force (see participation rates in 
Table 3-7). However, the employment rates within study area are highly heterogeneous, and data 
for the Mount Isa SA2 region (entirely within the study area) are very different to the data for the 
rest of the study area. For example, the Carpentaria SA2 region, which constitutes the greatest 
area of the Southern Gulf catchments, has far higher unemployment rates and far lower 
participation rates than the Queensland and national averages (Table 3-7). The Mount Isa SA2 
region provides a contrasting story with far lower unemployment and far higher participation rates 
than those of Queensland and Australia as a whole. 


Table 3-7 Key employment data for the Southern Gulf catchments 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
†Weighted averages of scores for SA2 regions falling wholly or partially within the boundaries of the catchments. 
Source: ABS (2006, 2011, 2016, 2021a) Census data 

There are also noticeable differences in the industries providing the most jobs within the region 
(Table 3-7), both within the catchments and compared to Queensland and Australia. ‘Healthcare 
and social assistance’, ‘Education and training’ and ‘Retail trade’ are important employers in the 
region and nationally. However, ‘Construction’ and ‘Professional, scientific and technical services’ 
feature within the top five industries by employment across the nation on average but are far less 
significant in the Southern Gulf catchments. ‘Public administration and safety’ is relatively more 
important to the employment prospects of workers in the Southern Gulf catchments than the 
national average. However, ‘Mining’ is the most important industry in the Southern Gulf 
catchments overall, and in the Mount Isa SA2 region within the catchments. It provides more than 


double the employment provided by ‘Healthcare and social assistance’ professions, the next most 
important employer in the region. The heterogeneity of the region is important to note, however, 
as mining is concentrated in the Mount Isa SA2 region (where most of the population is 
concentrated) but is of negligible importance across the rest of the catchments. 

Importantly to this Assessment, ‘Agriculture, forestry and fishing’ does not feature within the top 
five industries for the Southern Gulf catchments. However, the difference across the catchments is 
evident when the importance of agriculture in different parts of the catchments is considered. 
Overall, the proportion of employment in the study area provided by agriculture was only 2.7% in 
2021, similar to the rate for Queensland (2.6%) and Australia as a whole (2.3%). However, 
excluding Mount Isa, agriculture provided 17.5% of employment for the rest of the study area and 
17.1% in the Carpentaria SA2 region compared with just 0.3% in the Mount Isa region. 

Over the last three censuses (2021, 2016 and 2011), the percentage of employment from the 
agricultural sector nationally has been reported as 2.3%, 2.5% and 2.5%, respectively, and for 
Queensland, 2.6%, 2.8% and 2.7%, respectively, over the same years. That is, the proportion of 
employment in the agricultural sector has been small and fairly consistent. A broadly similar 
pattern (fairly consistent and of similar magnitude) is shown within the Southern Gulf catchments 
overall, with the sector having provided 2.7% of employment in 2021, 2.3% in 2016 and 2.5% in 
2011. 

The structural differences across the Assessment area are notable, as are the far higher 
dependencies on mining in Mount Isa and on agriculture across the rest of the catchments than 
are found in Queensland or across Australia. These differences can significantly affect the regional 
economic benefits that can result from development projects initiated within the region compared 
to development projects that may be initiated elsewhere. 

Land use 

The Southern Gulf catchments cover an area of about 108,200 km2, much of which is used for 
grazing (77%) (Figure 3-16) based on ACLUMP data current to 2017 for the NT and 2015 for 
Queensland. Of the remaining area, nearly all is conservation and protected land (16%). A further 
4% is classified as water and wetlands, most of which are marine plains and tidal areas located 
along the coast of the Gulf of Carpentaria. Intensive agriculture and cropping make up a very small 
portion of the catchment: rainfed and irrigated agriculture and intensive animal production 
together comprise less than just 0.04% of the area of the catchments. The other intensive localised 
land uses are transport, communications, services, utilities and urban infrastructure (0.06% of the 
area of the catchments) and mining (0.06%). 

While not considered a land use under the land use mapping (because it is a tenure) it is worth 
noting that Aboriginal freehold title makes up 12% of the Southern Gulf catchments. This land is 
held under the Commonwealth Aboriginal Land Rights (Northern Territory) Act 1976 (ALRA) in the 
NT and the Queensland Aboriginal Land Act 1991, including deeds of grant in trust (DOGIT), in 
Queensland. The title is inalienable freehold, which cannot be sold and is granted to Aboriginal 
Land Trusts (NT) or trustees (Queensland), which have the power to grant an interest over the 
land. 


 

Land use ACLUMP map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-16 Land use classification for the Southern Gulf catchments 

Note: land use data shown for the NT on this map is current to 2017 and 2015 for Queensland. 

Sources: NT Department of Environment, Parks and Water Security (2022); Queensland Government (2021b) 

 


Value of agriculture 

The estimated values of agricultural production for the Southern Gulf catchments and for 
Queensland as a whole are given in Table 3-8. The Assessment area provides a small proportion of 
the agricultural production of the state as a whole. The value of production is almost entirely 
derived from livestock, with a small amount of revenue from crops (predominantly from hay) 
(Table 3-8). 

The most recent annual survey data from the ABS describing the value of agriculture by different 
types of industries (2021–22 survey) are only available at a much larger scale (state and territory 
level) than the Southern Gulf catchments, making it difficult to accurately estimate the value of 
agricultural products within the catchments. Hence estimates have been made using the 2020–21 
agricultural Census data (Table 3-8), which were published at a finer spatial scale (SA2 level, as 
used for the socio-economic and demographic catchments estimates). 

Table 3-8 Value of agricultural production estimated for the Southern Gulf catchments and the value of agricultural 
production for Queensland for 2020–21 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
†Weighted averages of scores for SA2 regions falling wholly or partially within the boundaries of the catchments. 
Source: ABS (2022) Value of agricultural commodities in 2020–21 

Beef cattle production 

Agricultural production in the Southern Gulf catchments is dominated by extensive grazing of beef 
cattle, valued at $242.7 million in 2020–21 (Table 3-8) and covering about 77% of the Assessment 
area. Queensland’s beef cattle industry is the largest in Australia, and many Southern Gulf 
catchment properties turn off young animals (post weaning) to southern fattening properties for 
domestic and export beef. 

Sheep were the favoured stock in the earliest days of grazing. Not reaching profitable wool export 
expectations due to harsh climate, disease (liver fluke, footrot and lung worm), spear grass 
(Heteropogon spp.) and blowfly incidence, sheep were abandoned in favour of cattle, which have 
been more successful. The first stations in the Assessment area were formally taken up in the early 
1860s. 

The catchments in this Assessment do not match any stand-alone socio-economic or 
biogeographical regionalisations used by the cattle industry. However, published information from 
the ‘Northern Downs’ in Queensland to the south-east of the Southern Gulf (Bowen et al., 2020), 
the ‘Northern Gulf’ in Queensland directly to the east of the Southern Gulf (Bowen et al., 2019; 
Rolfe et al., 2016) and the ‘Gulf’ region, encompassing that part of the Assessment area within the 
NT (Cowley, 2014) have been used below and in Section 4.3.9 to describe the cattle industry 
within the Southern Gulf catchments. 


The typical beef production system in the area is a cow-calf operation with sale animals targeted 
to suit live export, slaughter and the United States grinding beef markets (Bowen et al., 2019; 
Bowen et al., 2020). A number of properties send cattle to properties further south for 
backgrounding and fattening. Some of these properties are owned under the one enterprise, with 
Rolfe et al. (2016) finding a mean of 2.2 properties per business within a survey of 18 properties in 
the Northern Gulf (Rolfe et al., 2016). Bowen et al. (2020) report that many businesses operate a 
breeding property in the Northern Gulf region in association with a growing property in the 
Northern Downs. However, their conclusion was that it was more profitable to turn off live export 
steers in the Northern Gulf and feed-on steers from the more productive Northern Downs (450 to 
480 kg liveweight). 

The within-year variation produced by the wet-dry climate is the main determinant for cattle 
production. Native pasture growth is dependent on rainfall; therefore, pasture growth is highest 
during the January to March period. During the dry season, the total standing biomass and the 
nutritive value of the vegetation declines. Changes in cattle liveweight closely follow this pattern 
with higher growth rates in the wet season than the dry season. Indeed, in many cases cattle lose 
liveweight and body condition throughout the dry season until the next pulse of growth initiated 
by wet-season rains. 

A large area of land is needed to maintain one unit of cattle (typically termed an AE, or adult 
equivalent). This carrying capacity of land is determined primarily by the soil (and landscape) type, 
the mean annual rainfall and its seasonality, and the consequent native vegetation type. Carrying 
capacities in the Southern Gulf catchments typically range from about 3.5 to 14.2 AE/km2 (i.e. 7 to 
28.6 ha/AE) on lands in ‘B’ condition (from a four point condition scale where ‘A’ is highest and ‘D’ 
is lowest). 

While the cattle typically graze on native pastures, many properties supplementary feed hay to 
the weaner cohort, partly to train them to be comfortable around humans for management 
purposes and partly to add to their growth rates during the dry season when the nutritive value 
and total standing biomass of native pastures is falling. Urea-based supplements and supplements 
containing phosphorus are fed to a range of age and sex classes of the cattle. The urea-based 
supplements provide a source of nitrogen for cattle grazing dry-season vegetation. The 
phosphorus supplements, mostly provided over the wet season, are used because phosphorus is 
deficient in many areas yet is required for many of the body’s functions, such as building bones, 
metabolising food and producing milk (Jackson et al., 2012). Winter (1988), working in the 
Katherine region, found substantial benefits to phosphorus fertilisation and supplementation, 
particularly in early and late wet-season periods and when grazing pastures which had been 
oversown with legumes. 

Cropping 

Dryland and irrigated agriculture comprise just 0.03% of the Southern Gulf catchments, with a 
total value of $0.9 million; it all occurs within the Queensland area of the Southern Gulf 
catchments. Most production is forage sorghum and hay, which are consumed locally. There is at 
least one small-scale cotton (Gossypium spp.) venture in the catchments. Recent changes to 
Queensland water regulation and new water releases in the neighbouring catchment of the 
Flinders River have spurred interest and expertise from growers in southern states to move into 
northern Australia, focusing on cotton and cereal crops. 


Horticulture has been proved suitable for the area by Gregory Farm, a 338-ha irrigated 
development near the Gregory locality where small cropping of mixed vegetables supplied 
localities in the area in the 1990s. Gregory Farm is currently baling both irrigated forage crops and 
some seasonal native grasses. 

Cropping and horticulture have proved to be agronomically suited to the local environment and 
soils but have been unable to be established as competitive local industries, partly because of 
difficulties with access to processing, distance to markets and high transport costs. 

Aquaculture and fisheries 

There is currently no active aquaculture in the Southern Gulf catchments. The closest aquaculture 
industry was a small prawn farm established in Karumba (40 km east of the boundary of the 
catchments) in 1974 and closed the following year for economic reasons (Australian Fisheries, 
1975). A comprehensive situational analysis of the aquaculture industry in northern Australia 
(Cobcroft et al., 2020) identifies key challenges, opportunities and emerging sectors. The 
Queensland Department of Agriculture and Fisheries supports the aquaculture industry, and 
research from the Northern Fisheries Centre in Cairns retains aquaculture infrastructure for 
aquaculture research at the Walkamin Research Facility. 

Offshore, the Southern Gulf catchments drain into one of the most valuable fisheries in the 
country. The Northern Prawn Fishery (NPF) spans the northern Australian coast from Cape 
Londonderry in WA to Cape York in Queensland (Figure 3-17). Most of the catch is landed at the 
ports of Darwin, Karumba and Cairns. Over the 10-year period from 2010–11 to 2019–20, the 
annual value of the catch from the NPF has varied from $65 million to $124 million with a mean of 
$100 million (Steven et al., 2021). The Southern Gulf catchments flow into the Karumba and West 
Mornington NPF regions (Figure 3-17), the most productive regions by annual prawn catch. 

Like many tropical fisheries, the target species exhibit an inshore–offshore larval life cycle and are 
dependent on inshore habitats, including estuaries, during the postlarval and juvenile phases 
(Vance et al., 1998). Monsoon-driven freshwater flood flows cue juvenile prawns to emigrate from 
estuaries to the fishing grounds, and flood magnitude explains 30% to 70% of annual catch 
variation, depending on the region of the catchments (Buckworth et al., 2014; Vance et al., 2003). 
Fishing activity for banana prawns and tiger prawns (Penaeus spp.), which combined constitute 
80% of the catch, is limited to two seasons: a shorter banana prawn season from April to June and 
a longer tiger prawn season from August to November. The specific dates of each season are 
adjusted depending on catch rates. Banana prawns generally form the majority of the annual 
prawn catch by volume. Key target and by-product species are detailed by Woodhams et al. 
(2011). The catch is often frozen on-board and sold in domestic and export markets. 

The NPF is managed by the Australian Government (via the Australian Fisheries Management 
Authority) through input controls, such as gear restrictions (number of boats and nets, length of 
nets) and restricted entry. Initially comprising over 200 vessels in the late 1960s, the number of 
vessels in the NPF has reduced to 52 trawlers and 19 licensed operators after management 
initiatives including effort reductions and vessel buy-back programs (Dichmont et al., 2008). Given 
recent efforts to alleviate fishing pressure in the NPF, there is little opportunity for further 
expansion of the industry. However, it is generally recognised that development of water 


resources in the Southern Gulf catchments would need to consider the downstream impacts on 
prawn breeding grounds and the NPF. 

Commercial barramundi fishing is also found in the study area (Bayliss et al., 2014), but is hard to 
quantify for the Southern Gulf catchments partly because of the mobility of the industry. 



Northern prawn fishery regions map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-17 Regions in the Northern Prawn Fishery and the North West Minerals Province 

The regions in alphabetical order are Arnhem-Wessels (AW), Coburg-Melville (CM), Fog Bay (FB), Joseph Bonaparte 
Gulf (JB), Karumba (KA), Mitchell (ML), North Groote (NG), South Groote (SG), Vanderlins (VL), Weipa (WA) and West 
Mornington (WM). 

Source: Dambacher et al. (2015) 

Mining 

Mining includes extraction of minerals (including coal), petroleum and gas, and quarrying. Mining 
is well established in Australia, and records indicate that before European settlement Indigenous 
Peoples quarried different types of stone (particularly gurabaan) and trading materials. In the 
Southern Gulf catchments, mineral exploration after European settlement dates back to 1882 
when Ernest Henry discovered copper at Mount Oxide, north of Mount Isa. 

Today, mining is the largest industry in the Southern Gulf catchments and in Queensland, was 
worth $86.5 billion in nominal gross value added (GVA) terms in 2022–23 (Queensland Treasury, 
2023). Most of the mining operations in the Southern Gulf catchments involve the extraction of 
copper, zinc, lead or silver. The North West Minerals Province within the Southern Gulf 
catchments (Figure 3-17) is considered to be one of the world’s most significant producing areas 
for base and precious metals (Queensland Department of Regional Development, Manufacturing 
and Water, 2021). About 75% of Queensland’s base metal mineral endowment is located in this 
province. Mines currently operating within the Southern Gulf catchments are mainly in the south 
and the lower rainfall areas, the largest mines occurring in and near Mount Isa (inset map on 


Figure 3-18). No mines are currently in operation in the NT portion of the Southern Gulf 
catchments, though as shown in 



Mineral occurrence and exploration leases, map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-18 Main commodity mineral occurrences and exploration tenements in the Southern Gulf catchments 

Sources: NT Geological Survey (2024); NT Government (2024b); Geological Survey of Queensland (2024); Queensland Government Open Data Portal 
(2024b) 




Mining is the largest employer in the Southern Gulf catchments with most of the labour force 
based in Mount Isa (Table 3-7). In 2021, the population of the Mount Isa urban area was just over 
18,000, and approximately 30% of the labour force was employed directly in mining in a range of 
occupations, including management, administration, professional and technical roles, and 
machinery operations (ABS, 2021c). Table 3-9 provides employee numbers for mines of various 
sizes. 
Table 3-9 Indicative numbers for employment in different types of mining operations in the Southern Gulf 
catchments 

MINE TYPE 

NUMBER OF EMPLOYEES AND 
CONTRACTORS 

SOURCE 



Very large base metal mine and associated 
processing and refining plants 

1000–2000 

Glencore (2023a) 

Mid-sized to large base metal mine 

300–600 

Evolution Mining (2023), MMG (2024) 

Mid-sized phosphate mine 

200–300 

Incitec Pivot (n.d.), Andre and Waterson (2023) 



Mount Isa region is currently in a period of transition. In 2005 the underground lead mine at 
Mount Isa closed due to a lack of ore (ABC, 2005), and the Mount Isa Mines underground copper 
operations are scheduled to cease in 2025 as the remaining mineral resources are deemed 
economically unviable. These include the underground copper mines Enterprise, X41 and Black 
Rock. The Lady Loretta zinc mine, a fly-in, fly-out operation 140 km north-west of Mount Isa, is 
also slated to close in 2025 (Glencore, 2023a). Despite these closures, the global consumptions of 
copper, zinc and nickel are projected to increase from about 24, 14 and 2 million tonnes in 2019, 
respectively, to 31, 15 and 4 million tonnes in 2030. 

Technological advances such as magnets and super magnets, motors, metal alloys, electronic and 
computing equipment, batteries, catalytic converters, petroleum refining and medical imaging 
have increased demand for rare earth elements (REEs), a specific group of 17 metals within the 
critical minerals family. 

In recognition of the importance of critical and strategic minerals to Australia’s modern 
technologies, economy and national security, the Australian Government released updated lists of 
Australia’s critical minerals and strategic materials, and both the NT and Queensland governments 
have programs to attract investment in critical mineral exploration and infrastructure. Critical 
minerals and strategic materials currently mined and/or the target of recent and current 
exploration programs in the Southern Gulf catchments include copper, zinc, phosphorus, the REEs 
and graphite. See the companion technical report on agricultural viability and socio-economics 
(Webster et al., 2024a) for a full list of critical minerals and strategic materials. 

Mineral occurrences for a wide range of commodities have been identified in the Southern Gulf 
catchments. As shown in Figure 3-18, approximately 68% of the Southern Gulf catchments is 
covered by mineral or petroleum exploration licences; the highest proportion occur in the 
Leichhardt catchment, in which 79% is covered by mineral exploration licences. 

Phosphate occurrences are present across the Southern Gulf catchments with a concentration 
around Lawn Hill and the Gunpowder localities (Figure 3-18). Exploration for uranium is currently 
being conducted in the catchments, and occurrences are in the south and north-west (Figure 
3-18). There are no operating uranium mines. In Queensland it is government policy not to grant


mining leases for uranium, although applications may still be made for mineral development 
licences or exploration permits for uranium (Queensland Department of Resources, 2021). 
Uranium mining is permitted in the NT (NT Government, 2024a). 

Several petroleum exploration bores have been drilled within the catchments. Twenty petroleum 
exploration bores were drilled on Mornington Island between 1959 and 1961; no hydrocarbons 
were reported, and the holes were plugged and abandoned. Thirteen wells were drilled in the 
Queensland part of the study area between 1959 and 2013. Gas was reported in three of the 
wells. Eleven of the holes are reported to have been plugged and abandoned or suspended and 
capped; two wells are reported to be current water bores (Queensland Government Open Data 
Portal, 2024a). One exploration petroleum well was drilled in 1992 in the NT part of the study area 
close to the western margin of the catchments and is reported to be dry, plugged and abandoned 
(NT Government, 2024b). 

Table 3-10 presents resource and reserve data for several major deposits in and on the margins of 
the Southern Gulf catchments. 

Table 3-10 Resource and reserve data for several major deposits in and on the margins of the Southern Gulf 
catchments 

MINE 

MASS 

(million t) 

MINERAL 

% 

MINERAL 

% 

MINERAL 

g/t 

LIFE OF 
MINE 

SOURCE 

 

 

 

Zinc 

Lead 

Silver 

 

 

George Fisher North Mine† (underground) 

 

 

 

 

To 2036 

Glencore, 
2023b, c 

Measured and indicated resources 2023 

164 

8.92 

3.34 

54 

 

 

Total ore reserves 2023 

45 

6.84 

3.31 

54 

 

 

George Fisher South Mine† (underground) 

 

 

 

 

To 2036 

Glencore, 
2023b, c 

Measured and indicated resources 2023 

55 

8.32 

5.02 

110 

 

 

Total ore reserves 2023 

12.9 

6.11 

4.76 

110 

 

 

Lady Loretta† (underground) 

 

 

 

 

To 2025 

Glencore, 
2023b, c 

Measured and indicated resources 2023 

5.1 

11.29 

2.48 

54 

 

 

Total ore reserves 2023 

3.5 

10.19 

2.22 

43 

 

 

Dugald River†* (underground) 

 

 

 

 

≥20 
years 

MMG, 2023, 
2024 

Measured, indicated and inferred resources 2023 

57 

11.7 

1.6 

23 

 

 

Proved and probable reserves 2023 

20 

10.8 

1.7 

40 

 

 

New Century‡ (tailings and exploration) 

 

 

 

 

To 2027 

Sibanye 
Stillwater, 
2023 

Measured and indicated resources 2022 

2.0 

5.6 

na†† 

na 

 

 

Proved and probable reserves 2022 

6.8 

3.0 

na 

na 

 

 



 


MINE 

MASS 

(million t) 

MINERAL 

% 

MINERAL 

% 

MINERAL 

g/t 

LIFE OF 
MINE 

SOURCE 









Copper 

Silver 





Mount Isa Copper† (open-cut and underground) 









To 2025 

Glencore, 
2023b, c 

Measured and indicated Resources 2023 

156 



1.70 

na 





Total ore reserves 2023 

6.5 



1.95 

na 





Capricorn Copper† (underground) 









≥2034 

29Metals, 
2022, 2024 

Measured, indicated and inferred resources 2023 

64.8 



1.8 

9 





Proved and probable reserves 2023 

19 



1.7 

12 









Phosphate 









Paradise South Phosphate§ (open-cut) 









≥20 
years 

Andre and 
Waterson, 
2023 

Measured, indicated and inferred resources 
(estimated total deposit) 

436.5 

9.4 









Proven and probable reserves (estimated total 
deposit) 

198.5 

12.7 











†Resources and reserves reported in accordance with the 2012 edition of the Australasian code for reporting of exploration results, mineral 
resources and ore reserves (Glencore, 2023b; Joint Ore Reserves Committee, 2012). 
‡Resources and reserves reported in accordance with the 2016 edition of The South African code for the reporting of exploration results, mineral 
resources and mineral reserves (SAMREC, 2016) and subpart 1300 under Regulation S-K of the US Securities Act of 1933 (Sibanye Stillwater, 2023). 
§Resources and reserves reported in accordance with the 2004 edition of the JORC Code (Joint Ore Reserves Committee, 2004). 
*The Dugald River mining operations occur outside the Southern Gulf catchments boundary although the tenements associated with the Dugald 
River project partially occur in the Southern Gulf catchments and the mine water supply is drawn from a purpose-built dam located inside the 
Leichhardt River catchment with backup water supplied from Lake Julius. 
††na = not applicable. 

Water use in mining and petroleum industries in the Southern Gulf catchments 

Water is central to the minerals and petroleum industries. Mining uses water in a variety of ways, 
including for transporting materials, chemical or physical processing, cooling, disposing and storing 
waste materials, washing, and suppressing dust. Potable water is used for areas that house mining 
staff (Prosser et al., 2011). Water is also extracted or ‘used’ during de-watering at mines that 
extend below the water level, such as Century Zinc Mine. Petroleum companies, which use 
relatively small volumes of water, produce water as a by-product of extraction. Water extracted 
during de-watering or as a by-product of petroleum extraction must be safely discharged and may 
need treatment. 

Water consumption at mining operations is highly variable (Table 3-11). The variations are due to 
a range of factors, including different mining methods, ore types, ore grades, processing 
treatments and definitions of water usage. The overall water balance on a site depends on climate 
conditions, which affect water availability at the site, and the ability to reuse and recycle water 
within process facilities (Northey and Haque, 2013). While not mined in the Southern Gulf 
catchments, coal is by far the largest user of water in the mining sector. The water used by mining 
enterprises does not need to be of potable quality. 


Table 3-11 Global water consumption in the mining and refining of selected metals 

PROCESSING STAGE 

MEAN WATER CONSUMPTION* 

(m3/tonne of metal) 

RANGE OF WATER CONSUMPTION§ 

(m3/tonne of metal) 

Copper concentrate† 

43.235 

9.673–99.550 

Gold metal‡ 

265,861 

79,949–477,000 

Lead concentrate† 

6.597 

0.528–11.754 

Manganese concentrate† 

1.404 

1.390–1.410 

Palladium metal‡ 

210,713 

56,779–327,874 

Platinum metal‡ 

313,496 

169,968–487,876 

Uranium concentrate (U3O8)† 

2,746 

46.2–8,207 

Zinc concentrate† 

11.93 

11.07–24.65 



†Metal concentrates are typically produced at the site where the ore is mined. 
‡Includes mining, smelting and refining of pure metals, assuming mining and processing are all located within a single region or separate regions but 
with similar water characteristics. 
*Mean water consumption values per /tonne of metal equivalent in the concentrates or refined metals. 
§Minimum and maximum water consumption values per tonne of metal equivalent in the concentrates or refined metals. 

Source: Meissner (2021) 

Because water is typically a very small fraction of total input cost, and mining produces high-value 
products, mining enterprises usually develop their own water supplies, which are often regulated 
separately to the water entitlement system (Prosser et al., 2011). In the Southern Gulf 
catchments, however, the concentration of mining and industrial activity resulted in sufficiently 
high water demand for the construction of large purpose-built reservoirs, including the privately 
funded Leichhardt Dam (Lake Moondarra) and Julius Dam (Lake Julius, now owned by SunWater). 
Dams in the Southern Gulf catchments are summarised in Chapter 5. Data on water use by mining 
in the Southern Gulf catchments are difficult to obtain. As described in Section 3.3.4, water use 
from Lake Julius between 2017–18 and 2012–22 was estimated to range from 5 to 14 GL/year, and 
from Lake Moondarra from 14 to 17 GL/year. Because these quantities represent a relatively 
modest proportion of the total supplemented water entitlements, there is scope for existing water 
storages, including Lake Mary Kathleen (12 GL capacity), which is only used for recreation, to 
support the expansion of mining activity in the Mount Isa region. 

Tourism 

Tourism in the Southern Gulf catchments is in a moderate state of development. Self-drive tourists 
are the predominant visitor market type in the Southern Gulf catchments, and they represent 87% 
of visitors to outback Queensland (Outback Queensland Tourism Association, 2021). A strategically 
promoted transcontinental ‘adventure’ self-drive traveller route, the Savannah Way, connects 
Cairns (Queensland) to Katherine (NT) then continues to Broome (WA), traversing the Southern 
Gulf catchments via Burketown (878 km from Cairns), Doomadgee and Hells Gate Roadhouse. 

Access to much of the Southern Gulf catchments is on unsealed roads. The largest domestic 
airport is at Mount Isa, which in offering a gateway to the region provides an advantage over many 
other parts of northern Australia. Smaller commercial regional airports are located in Burketown, 
Doomadgee and Gununa on Mornington Island, providing regional connections between Mount 
Isa and Cairns. All airports cater for light aircraft, and the nearest international airports are in 
Cairns and Darwin. Multiple accommodation options and types are available within and 


surrounding Burketown and Mount Isa; wet-season closures apply to some camping and 
accommodation businesses. 

Key inland attractions for visitors to the Southern Gulf catchments include the iconic Boodjamulla 
National Park (Aboriginal Land) and Wugudaji-Adels Grove. The Riversleigh World Heritage Area is 
renowned for its fossil fields containing Gondwanan specimens dating from 25 million years ago 
(Ma) (Queensland Department of Environment, Science and Innovation, 2024b). Visitor attractions 
and activities throughout the catchments include a range of nature-based activities such as bird 
and wildlife watching. Popular coastal attractions and activities include river cruises, four-wheel-
drive cultural tours, hot-air ballooning, fishing charters and astronomy (with one Indigenous-
owned tour operator from Burketown providing stargazing tours). The annual World Barramundi 
Fishing Championships in Burketown, the Gregory River Canoe Marathon and Burketown’s 
Morning Glory Festival are examples of annual events promoted to attract visitors to the region. 

As well as economic and employment opportunities, tourism can cause impacts such as native 
habitat loss, and foot traffic, bikes or vehicles may cause environmental damage such as erosion 
and a loss of amenity to local residents (Larson and Herr, 2008). Other risks include the spread of 
weeds (Chapter 7) and root rot fungus (Phytopthora cinnamomi) carried on vehicles and people 
(Pickering and Hill, 2007). 

The majority (79%) of the Southern Gulf catchments area is within Queensland, and this area is the 
most accessible to tourists. Visitor statistics in Queensland are usually reported at the local 
government area (LGA) scale (Figure 3-19). In the Southern Gulf catchments, visitor statistics are 
dominated by the Mount Isa LGA. The Mount Isa LGA reported 192 tourism businesses, of which 
76 were ‘non-employing’, 61 had four or fewer employees, 46 had between 5 and 19 employees, 
and 15 had 20 or more employees. Annual visitation to the Mount Isa LGA included 154,000 
domestic visitors (100,000 of which were intrastate) and 10,000 international visitors. Visitors 
stayed for a total of 660,000 visitor nights (a mean stay of four nights for domestic visitors and 
11 nights for international visitors), contributing more than $132 million in regional expenditure. 
However, a large proportion of the visitors to Mount Isa LGA (approximately 95,000) had travelled 
there for business purposes (Tourism Research Australia, 2019). A 2019 survey of Burke Shire LGA 
reported 11 tourism businesses, of which six were ‘non-employing’, and domestic overnight visitor 
expenditure in the shire was estimated to be $9 million/year. Other LGAs in the study area 
reported few if any tourism enterprises, while others such as the Cloncurry LGA are not 
considered representative because only small parts of the LGA are within the study area. 

High summer temperatures and humidity result in most tourist visitation occurring during the 
drier, cooler months with 80% of visitation to the Gulf Country falling between April and October. 
Road closures and seasonal business closures have further impacts on the ability of the region to 
have visitors year-round (Tourism Tropical North Queensland, 2024). This seasonality of visitation 
has flow-on effects for tourism-connected industries such as accommodation, food services and 
transport. 


 

Local governement area and Tourism regiont map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-19 Local government areas and the Tropical North Queensland tourism region that statistics on tourism 
visitation are extracted from 

Tourism development opportunities and considerations 

The state of northern Australia’s tourism economy is closely tied to the state of its ecosystems 
(Prideaux, 2013). With a large proportion of the Southern Gulf catchments in a ‘natural’ state 
relative to many parts of south-eastern Australia, there is potential for growth in nature-based 
tourism. However, like other remote areas of northern Australia, the region’s remoteness and 


distance from urban centres (Bugno and Polonsky, 2024), lack of supporting infrastructure, limited 
human capital and financial resources, and low awareness of tourism system characteristics 
(Summers et al., 2019), considerably constrain its potential. The seasonality of visitation also limits 
enterprise profitability (Bugno and Polonsky, 2024) and permanent employment opportunities. 
Also important to consider is that much of the catchment’s appeal to self-drive visitors is likely to 
be the absence of other people and commercial infrastructure, which presents opportunities for 
exploration and solitude (Lane and Waitt, 2007; Ooi and Laing, 2010). Hence development that 
alters the region’s current characteristics could be alienating to some current visitor markets. 

While water resource development for agriculture has the potential to negatively affect tourism 
and future opportunities in the Southern Gulf catchments, for example, through declining 
biodiversity and perceived reduced attractiveness (Pickering and Hill, 2007; Prideaux, 2013), such 
development may present opportunities to foster tourism growth. For example, Lake Argyle in the 
East Kimberley region (WA), developed as an irrigation dam to supply the Ord River Irrigation 
Area, is among northern WA’s must-see attractions, offering a wide range of tourism activities 
(https://www.australiasnorthwest.com/explore/kimberley/lake-argyle). While visitors to the 
Kimberley region reportedly perceived Lake Argyle in the same way they perceived some ‘natural’ 
local attractions such as billabongs, irrigated agriculture of the Ord River Irrigation Area is 
perceived differently, as being ‘domesticated’ (Waitt et al., 2003). 

Elsewhere in northern Australia, water resource infrastructure, including Fogg Dam (NT), Tinaroo 
Dam (Queensland) and Lake Moondarra (Queensland), has resulted in increased visitation by 
tourists for the enhanced wildlife or recreation opportunities they provide (e.g. Regional 
Development Australia, n.d.). However, the ongoing contributions of dam to their local economies 
vary. For example, the value of recreational fishing has been found to vary between dams 
depending upon whether there are other dams nearby and their proximity to tourism traffic (Rolfe 
and Prayaga, 2007). Visitation numbers to the Southern Gulf catchments suggests that the 
recreational fishing value of a new dam in the Southern Gulf catchments would be limited. 

Agritourism opportunities, for example, through property accommodation and other travel 
support (fuel), offer an opportunity for revenue diversification, although impediments such as 
highly variable seasonal demand limit profitability (Bugno and Polonsky, 2024). 

Tourism has the potential to enable economic development within Indigenous communities 
because Indigenous tourism enterprises, usually microbusinesses, often have some competitive 
advantages (Fuller et al., 2005). Successful tourism developments in regional and very remote 
areas such as the Southern Gulf catchments are highly likely to depend on establishing private and 
public sector partnerships, ensuring effective engagement and careful planning with Traditional 
Owners and regional stakeholders, and building interregional network connectivity and support 
(Greiner, 2010; Lundberg and Fredman, 2012). 

Given the importance of climate on tourism seasonality, demand and travel patterns in northern 
Australia (Hadwen et al., 2011; Kulendran and Dwyer, 2010), the increased temperatures and 
occurrence of extreme weather-related events (e.g. drought, flood, severe fires and cyclones) 
associated with climate change are likely to be significant threats to the industry in the future. 
These are likely to negatively affect tourist numbers, the also length and quality of the tourist 
season, tourism infrastructure including roads, and the appeal of the landscape and its changing 
biodiversity (Amelung and Nicholls, 2014; Prideaux, 2013). 


3.3.4 Current infrastructure 

Transport 

A modest road network services the Southern Gulf catchments, from sealed major highways to 
unsealed minor connection roads, all of which are subject to flooding and wet-season closures. 
The roads in the catchments have previously benefited from the Northern Australia Beef Roads 
Program, which has funded upgrades to key roads necessary for transporting cattle to improve the 
reliability and resilience of cattle supply chains in northern Australia, reducing freight costs and 
strengthening links to markets. 

The Barkly Highway (Figure 3-20) is the only sealed road between the NT and Queensland. It runs 
through the most southern part of the Leichhardt catchment at Mount Isa from the Three Ways 
Roadhouse just north of Tennant Creek, NT, east to Cloncurry, Queensland. This highway 
continues as the Flinders Highway to Townsville on the east coast, a key route in the national 
supply chain network supporting many industries, including agriculture and mining. 

All road network information in this section is from spatial data layers in the Transport Network 
Strategic Investment Tool (TraNSIT; Higgins et al., 2015). Trucking volumes calculated from TraNSIT 
show the largest volume of trailers occur on the Wills Developmental and Burke Developmental 
roads. Both of these roads are sealed and are predominantly used to support the cattle industry 
(Figure 3-26). 

National Highway 1 runs east–west across the Southern Gulf catchments through Burketown. It 
has sealed and unsealed sections and is also known as the Savannah Way, a popular four-wheel 
drive tourist route. Sections of this road also have local names (e.g. Doomadgee–Westmoreland 
Road). 

Rankings of the road network in the Southern Gulf catchments are shown in Figure 3-20. Heavy 
vehicle access restrictions for roads, as determined by the National Heavy Vehicle Regulator, show 
good connectivity for Type 2 road trains (Figure 3-21). These are vehicles up to 53 m in length, 
typically a prime mover pulling three 40-foot (approximately 12 m) trailers (Figure 3-22). A large 
proportion of the classified non-residential roads in the study area permit Type 2 road trains 
despite the poor road conditions of many of the local unsealed roads. Large (Type 2) road trains 
are permitted due to minimal safety issues from low traffic volumes and minimal road 
infrastructure restrictions (e.g. bridge limits, intersection turning safety). Drivers regularly use 
smaller vehicle configurations on the minor roads due to the difficult terrain and single lane 
access, particularly during wet conditions. 

Figure 3-24 shows the mean speed achieved for freight vehicles for the road network. The road 
speed limits are usually higher than the mean speed achieved for freight vehicles, particularly on 
unsealed roads. Heavy vehicles using such unsealed roads would usually achieve mean speeds of 
no more than 60 km/hour, and often lower when transporting livestock. 

Rail access in the Southern Gulf catchments is from a single point, Mount Isa, and has both a 
freight and passenger (the Inlander) service. The Great Northern Railway (also known as the 
Mount Isa line) is a critical link from the North West Minerals Province at Mount Isa to the Port of 
Townsville, primarily carrying bulk commodity transport (mostly minerals) for export. Several train 
operators manage rolling stock of incoming and outgoing freight. Queensland Rail (a statutory 
authority of the Queensland Government) owns the narrow-gauge (3 feet 6 inches, 1067 mm) line. 


The narrow gauge was chosen purely for economic reasons: because Queensland distances are 
large, the narrower gauge was cheaper to construct. 

 

Road rankings map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-20 Road rankings and conditions in the vicinity of the Southern Gulf catchments 

Rank 1 = well-maintained highways or other major roads, usually sealed; Rank 2 = secondary ‘state’ roads; 
Rank 3 = minor routes, usually unsealed local roads. The ‘Rank 1’ road is the Barkly Highway, which runs from the 
Three Ways Roadhouse (north of Tennant Creek) in the NT to Cloncurry, Queensland, east of Mount Isa. 


 

Road truck class map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-21 Roads accessible to Type 2 vehicles in the vicinity of the Southern Gulf catchments: minor roads are not 
classified 

Type 2 vehicles are illustrated in Figure 3-22. 




For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
Figure 3-22 Common configurations of heavy freight vehicles used for transporting agricultural goods in Australia 




Figure 3-23 Road conditions and distance to market impact the economics of development in the Southern Gulf 
catchments. 

Photo: CSIRO – Nathan Dyer 


 

Road speed map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-24 Mean speed achieved for freight vehicles on roads in the vicinity of the Southern Gulf catchments 

Data source: Spatial dataset of the location and attributes of roads and ferries sourced from HERE Technologies (2021). 

 


Supply chains and processing 

Table 3-12 provides volumes of commodities transported into and out of the Southern Gulf 
catchments annually by road, and Figure 3-26 shows the location of existing pastoral properties in 
the catchments. Agricultural production is dominated by beef cattle, which is reflected in the 
annual freight volumes moving across the road network in the Southern Gulf catchments 
according to TraNSIT records of truck movements. Live export of cattle accounts for the majority 
of cattle movements. There are also substantial transfers of cattle between properties and smaller 
volumes directed to domestic markets via abattoirs and feedlots in southern Queensland; 
however, the closest abattoir is Townsville. 

Table 3-12 Overview of commodities (excluding livestock) annually transported into and out of the Southern Gulf 
catchments 

Indicative transport costs are means for each commodity and include differences in distances between source and 
destinations. 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
Source: 2023 data from TraNSIT (Higgins et al., 2015) 
NA - data not available 

There are currently no processing facilities for other agricultural produce within the Southern Gulf 
catchments, although there have been assessments made for cotton processing (MITEZ, 2021). 

Rail access links Mount Isa to Townsville and the port, primarily carrying bulk commodity transport 
(mostly minerals) for export. The Port of Townsville is the closest port for bulk export and operates 
within the Great Barrier Reef World Heritage Area. This port is northern Australia’s largest 
container import facility, and exports primarily service the Queensland agricultural and mineral 
provinces. Port services also support imports and exports of general cargo for a range of domestic 
and industrial commodities (e.g. fuels, food, vehicles, commercial machinery and manufactured 
items). The port is managed and operated by a government-owned corporation, the Port of 
Townsville Limited, and currently operates with 11 berths. The Port of Lucinda (inset map on 


Figure 3-26), located on the east coast 100 km north of Townsville, is a sugar export facility. Ports 
North, also a corporation owned by the Queensland Government, manages eight ports in far north 
Queensland, four with sealed road access from the Southern Gulf catchments. The Port of 
Burketown, inside the catchments, is a declared port, but no commercial trade takes place. To the 
east just outside the catchments, the Port of Karumba provides for general cargo, fuel, fisheries 
products and zinc transhipment and has previously seen export of live cattle. On the east coast, 
the Port of Cairns, a regional port, services bulk and general cargo, a fishing fleet, cruise liners and 
passenger ferries to the reef. The export of raw sugar and molasses from the local sugar-growing 
districts is through the Port of Mourilyan. The only port in the western Gulf of Carpentaria is the 
Port of Bing Bong (inset map on 




Figure 3-25 Many roads are gravel in the Southern Gulf catchments, and often impassable in the wet season 

Photo: CSIRO – Nathan Dyer 




 

Truck volume and ports map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-26 Annual amounts of trucking in the Southern Gulf catchments and the locations of pastoral properties 
and ports 

Declared ports (shown on the inset map) all carry out commercial operations except the Port of Burketown. 

The thickness of purple lines indicates the volume of traffic (as number of trailers per year) on regional roads 
connecting properties and enterprises. 


Energy 

The only major electricity network in north-western Queensland is the North West Power System 
(NWPS), which connects Mount Isa to the Century Mine (zinc) near Lawn Hill in the north and 
Cloncurry to the east outside the Southern Gulf catchments (Figure 3-27). The NWPS is isolated 
from the National Electricity Market (NEM), Australia’s largest electricity network, which stretches 
along Australia’s east coast from northern Queensland to Tasmania and SA. 



Power generation and transmission map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-27 Electricity generation and transmission network and pipelines in the Southern Gulf catchments 














Most power stations in the NWPS are gas-fired, which has resulted in high electricity costs 
compared to the NEM (Queensland Government, 2021a). The NWPS does not operate via an 
electricity market, but rather has negotiated supply contracts, which suits large industrial and 
mining operations in the region (APA, 2022). 
Ergon Energy operates the distribution network in this region and all country areas of Queensland 
(Figure 3-27). Powerlink operates the NEM transmission network in Queensland (AEMO, 2023). 
Already one of the world’s longest interconnected power systems, the Queensland Government 
plans to connect the NEM to the NWPS with the development of the CopperString 2032 project. 
The connection will consist of a 1100 km transmission line from Townsville in the NEM to Mount 
Isa in the NWPS. Little benefit will be realised within the Southern Gulf catchments outside the 
Mount Isa area without additional transmission line infrastructure. 
The Diamantina Power Station, near Mount Isa, is a combined-cycle gas turbine plant with a 
capacity of 242 MW. This power station supplies the NWPS. It also has 60 MW of backup from the 
nearby open-cycle gas turbine Leichhardt Power Station. Doomadgee, Burketown and Gununa are 
not connected to any grids and have their own community power stations, which are supplied and 
maintained by Ergon Energy. Burketown and Gununa are isolated diesel power stations and 
Doomadgee’s 568 kW ground-mounted solar farm and 105 kW of rooftop solar (on four 
Doomadgee Shire Council buildings) provide power with backup supplied by diesel generator. 
Gas pipelines are located in the most southerly part of the Southern Gulf catchments where the 
Northern Gas Pipeline stretches from the NT to Mount Isa, and then the Carpentaria Gas Pipeline 
connects Mount Isa to Ballera in southern Queensland (Australian Energy Regulator, 2021). 
Renewable energy potential in the Southern Gulf catchments 
The Southern Gulf catchments have some of the best solar resources in Australia and a low to 
modest wind resource relative to other locations in Australia. A convenient metric for comparing 
renewable energy technologies is using the capacity factor of an energy plant, which is the ratio of 
electricity generated over one year to the nameplate capacity of the solar or wind farm. For 
example, for a capacity factor of 0.25, each 1 MW of a solar/wind farm will generate about 
2190 MWh of electricity per year. In the Southern Gulf catchments, solar photovoltaic capacity 
factors are uniformly high, ranging between 0.23 to 0.25. In contrast, in southern Australia and 
along the east coast, the capacity factor can be as low as 0.12 (Figure 3-28). 
Wind resources for the Southern Gulf catchments are shown in Figure 3-29 as a capacity factor at 
a turbine hub height of 150 m, which is a typical height for a commercial wind turbine. Although 
wind capacity factors in the Southern Gulf catchments are comparable to, and in some cases 
higher than, solar capacity factors, wind farms have a higher capital cost, which can result in a 
higher cost of electricity production. This is particularly the case for smaller wind turbines than 
those whose results are shown in Figure 3-29. The generation capacity of these smaller turbines is 
more likely to be commensurate with the energy requirements of a farm-scale irrigation 
enterprise. Furthermore solar is modular and scalable and is easier to maintain in remote locations 
than wind turbines. Wind energy is also a relatively mature technology, and projections of the 
levelised cost of wind in 2040 suggest that its cost is plateauing. In contrast, solar photovoltaic is 
projected to steadily decrease such that by 2040 the levelised cost of solar photovoltaic would be 
26% to 34% lower than the cost of wind on average (Graham et al., 2023). With the exception of 


Kajabbi, one of the few locations with soils potentially suitable for irrigated agriculture and a grid 
connection, solar photovoltaic is the most viable renewable technology across most of the 
Southern Gulf catchments. Having a grid connection at Kajabbi enables excess renewable 
electricity to be sold to the grid, potentially changing the economic viability of wind turbines. 

 

Solar photovoltaic capacity map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-28 Solar photovoltaic capacity factors in the Southern Gulf catchments 

Inset shows solar photovoltaic capacity factors across Australia. Note: the inset map uses a different colour ramp 


 

Wind capacity map
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For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-29 Wind capacity factors in the Southern Gulf catchments 

Inset shows wind capacity factors across Australia. Note: the inset map uses a different colour ramp. 

At locations distant from a grid connection, such as Doomadgee, it was found that, based on 
current capital costs and a diesel cost of $1.50/litre (including any rebate), diesel generators were 
the most cost-effective technology for supplying power to farm infrastructure requiring electricity 
24 hours/day or requiring electricity for 30% or fewer days per year. For farm infrastructure 
operating more than 50% days of the year, and for 12 hours/day or less, a hybrid diesel – solar 


photovoltaic farm with the renewable fraction between 50% and 75% is most the cost-effective 
technology. The exception is for farm infrastructure requiring electricity for 4 and 12 hours/day 
and 365 days/year, for which a 100% solar photovoltaic farm (with batteries) was most the most 
cost-effective way to provide power. Under a higher cost of diesel ($2.50/litre including rebates), 
the results were similar except a 100% renewable system with batteries was most cost-effective 
when electricity had to be supplied for 80% of days or more. Based on solar photovoltaic and 
battery technology costs projected to 2040, it was found that hybrid diesel – solar photovoltaic 
systems (with batteries) were most cost-effective when farm infrastructure was operated for 30% 
of days/year or higher for 12 to 24 hours/day, or 10% of days/year when only operated for a 
maximum of 8 hours/day at the higher diesel price (i.e. $2.50/litre). See the companion technical 
report on techno-economic analysis of electricity supply (Hayward, 2024) for more detail. 

Hybrid grid electricity – renewable systems without batteries are more viable in all instances 
where soils suitable for irrigated agriculture are located near an existing electricity transmission 
line and it is possible to sell modest amounts of surplus energy to the grid (i.e. assuming the size of 
the renewable farm cannot be greater than 25% of the electrical load and assuming expected 
revenue was only equal to the levelised cost of electricity of wind; see Hayward (2024) for more 
detail). Solar technology tends to be more viable when the demand is 4 hours/day or less, or the 
infrastructure is operated is for 10% or fewer days per year. 

Water 

Communities and industries in the Southern Gulf catchments source their water from either 
surface water or groundwater for a variety of purposes, including: (i) stock and domestic uses, 
(ii) town and community water supplies, and (iii) industries such as agriculture and mining. For 
some uses, surface water is pumped from the occasional dam or stream. In the case of Mount Isa’s 
water supply, a major water transmission pipeline supported by pumping stations is used to 
transfer water from the dams on Lake Julius and Lake Moondarra for treatment prior to 
distribution in Mount Isa. Small quantities of groundwater (<5 ML/year) may be pumped from a 
single bore for stock and domestic use. Where larger amounts of groundwater are required (tens 
to hundreds of megalitres per year), water may be pumped from a borefield consisting of multiple 
connected production bores. Such applications include town and community water supplies and 
irrigated agriculture. 

A water licence is required for some water uses, such as water use for town and community water 
supply or applications by industry. Other applications, such as stock and domestic use, may or may 
not require a water licence. This will depend upon the proposed location and magnitude of water 
take and whether it occurs within a water plan area or could interfere with a watercourse, lake or 
spring (Queensland Government, 2016). In some areas of the catchments, water use is under a 
water plan – each plan covers a different extent and plan areas may overlay another plan area 
(Figure 3-30). Surface water plans will overlay the Water Plan (Gulf) 2007 area (Figure 3-30). 
Groundwater plans may overlay the Great Artesian Basin and Other Regional Aquifers (GABORA) 
Plan area. The GABORA Water Plan manages groundwater sources from multiple aquifers hosted 
in different geological units and within different groundwater sub-areas (Figure 3-30). 

In 2018, the Queensland Water Act 2000 was changed to formally recognise the importance of 
water resources to Aboriginal and Torres Strait Islander Peoples. It required new and replacement 
water plans to explicitly state ‘cultural outcomes’ as distinct from social, economic and 


environmental outcomes. Water plans can include strategies for monitoring and reporting on the 
achievement of cultural outcomes. For example, the Water Plan (Gulf) 2007 (Queensland 
Government, 2007) includes 30,550 ML as an Indigenous reserve (

 

Surface water and groundwater licences, map
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Figure 3-30 Location, type and volume of annual licensed surface water and groundwater entitlements across the 
Southern Gulf catchments 

License locations are not precise as deidentified location information was used. Unallocated reserves provided for in 
the Water Plan (Gulf) 2007 (34.3 GL/y in total), are not shown. Currently there are no active groundwater or surface 
water licences in the NT portion of the Southern Gulf catchments. 

Data sources: Spatial dataset of the location and attributes for water licences and permits across Queensland sourced from the Queensland 
Department of Regional Development, Manufacturing and Water (2023) 


Table 3-13 Unallocated surface water in the Queensland part of the Southern Gulf catchments 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
Source: Waschka and Macintosh (2023) 

Surface water entitlements 

Surface water licences with a volumetric entitlement occur at a variety of locations and from a 
variety of sources across the Southern Gulf catchments (Figure 3-30). Currently, 
27 unsupplemented surface water licences with a volumetric entitlement have been granted 
across the Southern Gulf catchments. These licenses have been granted for a combination of uses, 
including agriculture and aquaculture, across various parts of the catchments. They have a 
combined total of about 38,000 ML/year (38 GL/year) (Figure 3-30). The largest entitlements 
(i.e. between 1000 and 8000 ML/year) have been granted for use in agriculture. Some moderate 
entitlements (between 400 and 1000 ML/year) have been granted for town and community water 
supply at Mount Isa, Gregory and Kajabbi (Figure 3-30). Much smaller surface water entitlements 
(<50 ML/year), are associated with stock use (Figure 3-30). 

There are also supplemented water entitlements supplied by Lake Julius (48.85 GL) and Lake 
Moondarra (26.3 GL). These entitlements are used for Mount Isa town water supply and industrial 
use, as well supply to Cloncurry and Ernest Henry Mine via the North West Queensland Water 
Pipeline from Lake Julius. Use of these entitlements historically has been low, over the 2017–18 to 
2021–22 water years (1 September to 31 August), 11% to 29% of authorised entitlements from 
Lake Julius were used, and 52% to 66% from Lake Moondarra (Queensland Department of 
Regional Development, Manufacturing and Water, 2023). 

Groundwater entitlements 

Groundwater licences with a volumetric entitlement also occur at a variety of locations and from a 
variety of sources for different uses across the catchments. Currently 13 groundwater licences 
with a volumetric entitlement have been granted for a variety of applications with a combined 
total of about 3.5 GL/year. The largest entitlements (150 to 1400 ML/year) are associated with 
industrial use in mining with the water sourced from various aquifers hosted in the Paradise Creek 
Formation and the Currant Bush and Thorntonia limestones (Figure 3-30). Two licensed 
entitlements of approximately 100 ML/year have been granted for town and community water 
supplies at Burketown and Gununa (Mornington Island). Both licences have been granted for 
groundwater sources from the Gilbert River Formation of the Great Artesian Basin (Figure 3-30). 
The smallest groundwater licences (<100 ML/year) have been granted for a variety of industrial 
and agricultural uses with groundwater sourced from a variety of aquifers hosted in different 
geological units (Figure 3-30). 

The Century Zinc Mine, located about 15 km to the south-east of Lawn Hill, was Australia’s largest 
open-pit zinc mine before its closure in 2016. It used to de-water part of the Cambrian Limestone 
Aquifer (CLA) hosted in the Thorntonia Limestone that overlies zinc deposits hosted in the 


Proterozoic Lawn Hill Formation. When fully operational, the mine was reported to be extracting 
about 19 GL/year of groundwater in the early 2000s and about 10 GL/year in the mid-2010s. 
Currently, less than 1 GL/year of groundwater is being extracted at the site. The cessation in 
de-watering at the site is likely to have resulted in recovery of groundwater levels and storage in 
the CLA around the site. This may also include an onset of increased discharge from the aquifer to 
Lawn Hill Creek. However, the timescales for changes in groundwater flow are likely to be in the 
order of tens of years or longer, and further investigation would be required to confirm this. For 
more information on groundwater resources of the Southern Gulf catchments, see the companion 
technical report on groundwater characterisation (Raiber et al., 2024). 

Community infrastructure 

The availability of community services and facilities in remote areas can play an important role in 
attracting people to or deterring people from living in those areas. Development of remote areas, 
therefore, needs to consider whether housing, education and healthcare are sufficient to support 
the anticipated growth in population and demand, or to what extent these would need to be 
expanded. 

Like most remote parts of Australia, there are limited primary health resources in the Southern 
Gulf catchments apart from in the largest population centre, Mount Isa. Mount Isa Hospital has 
80 beds and is a Queensland Level 4 (Clinical Services Capability Framework) Specialist Service 
Base Hospital delivering moderately complex services. Telehealth and specialist outreach services 
are provided from Mount Isa to remote hospital and health service facilities in the Assessment 
area. General practitioners and allied health professionals provide most primary healthcare in 
Mount Isa. 

The Southern Gulf catchments are serviced by the national primary health network (PHN). 
Australia is divided into 31 PHNs: one of these covers the whole of the NT, and in Queensland, the 
area is covered by the Western Queensland PHN. These PHN regions are divided into districts. In 
the NT, the Katherine Health Service District (HSD) (also known as the Big Rivers Region) and the 
Barkly HSD provide health services to remote communities and properties in the NT part of the 
Southern Gulf catchments. There are no hospitals inside the NT section of the Southern Gulf 
catchments. The nearest healthcare resource is Robinson River Community Health Centre, a nurse-
led clinic approximately 100 km north of the western boundary of the catchments. 

The Queensland North West Hospital and Health Service at Mount Isa works closely with local 
hospital and clinic networks in smaller communities to provide remote health services. There are 
three hospitals inside the boundaries of the catchments: Burketown (Level 1), Doomadgee 
(Level 2) and Mornington Island (Level 2). They provide low-complexity care services and specialist 
visiting services, including paediatrics, dietetics, oral health and speech therapy. Gidgee Healing 
Aboriginal Medical Service provides primary and community healthcare in Doomadgee and on 
Mornington Island. 

Three Queensland hospitals located close to but outside the boundaries of the catchments provide 
health services: Camooweal (Level 1), Cloncurry (Level 1) and Normanton (Level 2). The Royal 
Flying Doctor Service also covers the region, providing weekly general practitioner and fortnightly 
child health clinics to some communities and properties. 


The mining town of Mount Isa has all the facilities of a large rural town. It is the central hub for 
education in the Southern Gulf catchments, with three public schools totalling 1240 full-time 
equivalent (FTE) enrolled students and 129.4 teachers (FTE) in 2022 (Table 3-14). Delivering 
education to the smaller communities are three schools, Doomadgee, Burketown and Mornington 
Island, which are all in the Queensland part of the catchments. A total of 577.2 (FTE) students are 
enrolled in these schools with 60.8 (FTE) teachers. A further four schools are just outside the 
Southern Gulf catchments: Camooweal, Cloncurry and Normanton in Queensland and Robinson 
River in the north of the NT part of the catchments. Mount Isa School of the Air, with 176 students 
(FTE), also covers the properties and communities in the study area. 

Table 3-14 Schools servicing the Southern Gulf catchments 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
†FTE = full-time equivalent 
Source: ACARA (2023) (data presented with permission) 

At the time of the 2021 Census, around 19% of private dwellings were unoccupied, which is 
around double the Queensland and national means for unoccupied dwellings (Table 3-15). This 
suggests that the current pool of housing may have some capacity to absorb small future increases 
in population. 


Table 3-15 Number and percentage of unoccupied dwellings and population for the Southern Gulf catchments 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
†Weighted averages of scores for SA2 regions falling wholly or partially within the boundaries of the catchments. 
Source: ABS (2021b) Census data 

3.4 Indigenous values, rights, interests and development goals 

3.4.1 Introduction and research scope 

This section gives an overview of the information needed on Indigenous water issues in the 
Assessment area to provide foundations for community consultations and involvement in further 
research, and planning and decision-making with government and industry. It provides some key 
background information about the Indigenous Peoples in the Assessment area and their specific 
values, rights, interests and objectives in relation to water. The material in this section draws 
largely from the literature and is intended to give an overview on water-related development 
information needs. Additional information on Indigenous aspirations, interests and water values is 
presented in the companion technical report by Lyons et al. (2024). 

Indigenous Peoples represent a substantial and growing proportion of the population across 
northern Australia, and they have secured rights and interests in over 70% of the land. They 
control significant natural and cultural resource assets, including land, water and coastlines. 
Indigenous Peoples are crucial owners and will increasingly become critical partners, co-investors 
and stakeholders in future development. Understanding the past is essential to understanding 
present circumstances and forms of organisation to engage with development options and future 
possibilities. 

The material provided here begins with historical information and a description of the 
contemporary ownership of the Assessment area. It then focuses on development in the lower 
reaches of the Southern Gulf catchments. Section 3.4.2 describes the past habitation by 
Indigenous Peoples, the significance of water in habitation patterns, and the impact of exploration 
and colonisation processes. Section 3.4.3 reviews the contemporary situation with respect to 
Indigenous residence, land ownership and access. Section 3.4.4 outlines Indigenous water values 
and responses to development, and Section 3.4.5 describes Indigenous-generated development 
objectives. 

Information on Indigenous water values and perspectives on general water development and 
associated agriculture has been given limited consideration within the Assessment area. 
Significant research has been undertaken on pastoralism and mining, particularly the relations 
between Indigenous and non-Indigenous societies in these sectors. The work undertaken here, 


and in the companion technical report on Indigenous aspirations, interests and water values 
(Lyons et al., 2024), addresses these information needs. 

Engagement with Indigenous Peoples is a strong aspiration across governments and key industries. 
Nevertheless, engagement models can vary considerably, and competing understandings of what 
‘engagement’ means (e.g. consultation, involvement, partnership) can substantially affect 
successful outcomes. Standard stakeholder models can also marginalise Indigenous interests, 
reducing what Indigenous Peoples understand as prior and inalienable ownership rights to a single 
‘stake’ equivalent to all others at the table. As significant land rights and interest holders, 
Indigenous Peoples in northern Australia have expressed a desire to drive alternative engagement 
practices to strengthen local leadership and knowledge partnerships (NAILSMA, 2020). 

Guided by advice from the Carpentaria Land Council Aboriginal Corporation (CLCAC) and feedback 
from other Aboriginal corporations, the Assessment activity on Indigenous aspirations, 
development goals and water values was redesigned to test and understand how findings from 
the previous Assessments may be relevant to Traditional Owners in the Southern Gulf catchments. 
At the time of writing this report, on-ground consultations were being planned under a joint 
CSIRO–CLCAC proposal. This section summarises Indigenous values, rights, interests and 
development goals sourced from publicly available literature. It is complemented by a legal 
analysis of Indigenous water rights and interests in the NT and Queensland. 

3.4.2 Pre-colonial and colonial history 

Pre-colonial Indigenous society 

Pre-colonial Indigenous society is characterised by long residence times; a detailed knowledge of 
ecology and food gathering techniques on which survival depended; complex systems of kinship 
and territorial organisation; communal and inalienable ownership of land; and a sophisticated set 
of religious beliefs, often known as the Dreaming. These Indigenous religious cosmologies provide 
a source of spiritual and emotional connection and guidance on identity, language, law, territorial 
boundaries and economic relationships (Merlan, 1982; Rose, 2004; Strang, 2005). From an 
Indigenous perspective, ancestral powers are always present in the landscape, intimately 
connected to People, Country and culture. Mythological creators, collectively referred to as 
Dreaming, have imbued significance to places through creation, leaving evidence of their actions 
and presence through features in the landscape (Martin and Trigger, 2015; Merlan, 1982; Rose, 
2004). The cosmological belief of the Dreaming is present among many Indigenous groups. 
Totemic figures can be animals or plants, take human-like or inanimate object forms, or be 
sentient beings with agency to act (Martin and Trigger, 2015; Merlan, 1982; Peterson, 2013). 
Those powers must be considered in any action that takes place on Country. 

Northern Australia contains archaeological evidence of Indigenous habitation stretching back 
many tens of thousands of years (Taçon, 2008), but gaps remain in the published archaeological 
record. Resource-rich riverine habitats were central to Indigenous economies based on seasonally 
organised hunting, gathering and fishing. Rivers were also major corridors for social interaction 
and contain many sites of cultural importance (Barber and Jackson, 2014; McIntyre-Tamwoy et al., 
2013; Taçon, 2008). 


Colonisation 

The first confrontations of European exploration, settlement and the processes of colonisation 
resulted in significant levels of violence towards Indigenous Peoples. Continued conquest of 
Indigenous Peoples and the control of their lands brought about the breakdown of the structure 
and function of existing Indigenous societies, including the decimation of language groups. 

Access to land and water was critical to both enterprising pastoral interests and Indigenous 
subsistence society (Merlan, 1978; Morphy and Morphy, 1981; Scambary, 2013; Strang, 1997). The 
damage and ruin to water sources caused by cattle affected Indigenous Peoples’ access to other 
resources on Indigenous lands, which intensified conflicts and lead to Indigenous Peoples taking 
cattle for sustenance and retaliation (McGrath, 1987; Merlan, 1978, 1986; Strang, 1997). 
Avoidance, armed defensiveness, skirmishes and violent clashes occurred in colonial relationships 
as a result of competition for food and water resources, colonial attitudes and cultural 
misunderstandings (Merlan, 1978). Historical exploration and settlement were practices that 
placed a colonial overlay of interests and boundaries on Indigenous territories and resources 
(Scambary, 2013). 

The opening of the Gulf Country to the pastoralism frontier occurred with the search parties sent 
from Victoria, Queensland and SA to find the explorers Burke and Wills after their disappearance 
(Scambary, 2013). Cattle arrived from 1861 onwards after the expedition parties identified fertile 
pastoral lands. Within 4 years, three stations were established in the Southern Gulf catchments: 
Beames Brook, Floraville and Gregory Downs stations (Scambary, 2013). Pastoral stations were 
first established in more accessible and watered lands. Groups belonging to those areas bore the 
brunt of the displacement activity (Trigger, 1992). People moved in various directions to find 
refuge: some moved to the coast and others retreated to the NT. Gregory Downs Station remains 
one of the larger stations in the catchments. The subsequent development of available pastoral 
lands in the 1860s led to the establishment of Burketown on Gangalidda Country in 1865 (Martin, 
2012). 

The establishment of the Coast Track in 1872 invigorated a new focus on pastoralism in northern 
Australia, in the southern region of the Gulf of Carpentaria and into the NT. This attention to 
developing northern Australia was the start of violent relationships between Indigenous Peoples 
and settlers in the frontier (Roberts, 2009). The Coast Track remains notorious for the violence 
perpetrated against Indigenous Peoples, a period called the ‘Wild Times’. 

Police stations were established along the Coast Track in the 1880s in response to station owner 
complaints of cattle stealing by Indigenous Peoples and to establish law and order in newly settled 
areas (Merlan, 1986; Roberts, 2009; Strang, 1997). Later, the Native Mounted Police helped 
manage the Indigenous labour working on stations (Kidd, 1997). The 1890s drought that pushed 
stock to the coastal fringes affected the Waanyi People most. The Waanyi People, whose lands in 
the west had been taken up by pastoral stations, moved to the east to secure food supplies from 
depots and stations in Queensland, obtain tobacco and gain protection from the violence (Martin 
and Trigger, 2015; Martin, 2012). 

Burketown on Gangalidda land was established as a supply and support town in 1865 but was later 
abandoned due to fever. It has continued to be a community township. 


The Queensland Aboriginals Protection and Restriction of the Sale of Opium Act 1897 legislated for 
the protection of Aboriginal people and triggered the establishment of Aboriginal reserve lands 
(Kidd, 1997). Under the Act, the government could remove and relocate individuals and families 
and regulate the employment of Indigenous Peoples in the pastoral industry (Kidd, 1997). The 
legislation was designed to reduce Indigenous resistance to pastoral activities and stock loss due 
to changed resource conditions from the new settler interests (Roberts, 2009; Scambary, 2013). At 
the same time, the pastoral industry relied heavily on Indigenous labour and knowledge of 
Country to sustain itself. 

As a result of the application of the legislation to Indigenous Peoples in Queensland, the Native 
Mounted Police directed its attention to preventing the movement of NT-based Indigenous 
Peoples into Queensland (Roberts, 2005). Consequently, Waanyi People continue to live and 
manage their affairs across historically established jurisdictional borders (Roberts, 2005). 

The Act included a provision for establishing minimum wages, payable under agreed individual 
negotiations. The payment of wages was under the discretion of the Protector of Aborigines, who 
determined an individual’s access to their wages. Wages were paid into trusts that people could 
not access, and in many cases, money did not reach the workers (Kidd, 1997). Unknowingly, 
individuals entered into agreements that indentured them to stations. In 2019, the Queensland 
Government agreed to pay $190 million in stolen wages to settle a class action by Aboriginal and 
Torres Strait Islander Peoples for unpaid wages dating back to the late 19th century and up to the 
1980s. 

A Presbyterian mission was established on Mornington Island in 1914 and later in the location of 
Doomadgee in 1936 (Long, 1970). In the 1930s, many Indigenous Peoples were living on the 
Mornington Island and Doomadgee missions. The missions remained in government control for 
50 years and systematically dismantled the social and political systems and kinship responsibilities 
(Long, 1970). The missions became important sources of labour for stations and protectors of 
Aboriginal people (Long, 1970). Mornington Island and Doomadgee missions transitioned to 
community governments in 1978 and 1983, respectively (Memmott and Channells, 2004). 

3.4.3 Contemporary Indigenous ownership, management, residence and 
representation 

Despite the tensions, disruptions and trauma that stemmed from colonisation, Indigenous Peoples 
remain closely tied to their territory associations, ceremonial relationships and genealogical and 
historical residential ties (Martin and Trigger, 2015; Trigger, 1987, 1997). Some of these 
connections are formally recognised by the Australian state and confer particular rights and 
interests. 

Indigenous Traditional Ownership 

The Indigenous owners’ language groups of the Southern Gulf catchments are: 


•Leichhardt catchment – Kalkadoon, Mitakoodi, Wakabunga, Mayi-Kutuna, Mayi-Thankurti, 
Mayi-Yapi, Mayi-Yali and Kukatj•Nicholson catchment – Waanyi, Garawa, Wakabunga, Nguburinji, and Gangalidda•Wellesley Islands – Lardil, Yangkaal, Kaiadilt



•Settlement catchment – Garawa, Gangalidda
•Morning Inlet catchment – Kukatj.


Patterns of ownership and language affiliation follow features of the landscape and waterways 
and are reflected in the place names and songs of significant Dreamings and totemic figures. 
Formal boundaries are also negotiated between groups. In some areas, there can be overlapping 
claims and sharing of territories. The process of colonisation has also shaped land interests. 
Residential information regarding the identification of potential owners and interest holders is 
provided by registered organisations such as the CLCAC, Queensland South Native Title Services 
and prescribed bodies corporate (PBCs) such as the Kalkadoon Native Title Aboriginal Corporation 
RNTBC. 

Across Australia, the primary form of recognition for Indigenous interests is native title and 
associated Indigenous Land Use Agreements (ILUAs). Native title provides a bundle of rights (such 
as access, hunting and fishing) determined through a legal process. The Australian legal system 
formally recognises Indigenous exclusive native title interests in 10.8% of the Southern Gulf 
catchments. 

Native title, Aboriginal Land Act deeds of grant in trust (DOGIT), the Aboriginal Land Rights 
(Northern Territory) Act 1976 (ALRA), national park co-management and ILUAs are the formal ways 
in which contemporary Indigenous Peoples of the Southern Gulf catchments exercise some degree 
of management control over large areas of their traditional lands and have ownership. In the NT 
jurisdiction of the Nicholson River, Waanyi Garawa Country, the ALRA provides a form of collective 
freehold ownership. The entire Waanyi Garawa Aboriginal Land Trust, an area of some 
11,000 km2, is an Indigenous Protected Area (Ganalanga-Mindibirrina Indigenous Protected Area) 
(Figure 3-4). Within Queensland, Doomadgee and Mornington Island and the surrounding islands 
have been granted DOGIT (Figure 3-31). DOGIT is a legal framework that enables Aboriginal and 
Torres Strait Islander Peoples to ‘self-manage’ their communities. 

Indigenous Peoples of the Southern Gulf catchments in Queensland exercise some degree of 
management control over large areas of traditional lands through native title determinations 
(Figure 3-32). The Waanyi Native Title area is the most extensive determination in the state. 
Native title (non-exclusive) areas in the Southern Gulf catchments include the jointly managed 
Boodjamulla National Park (Aboriginal Land), several extensive pastoral holdings, the Bidunggu 
Aboriginal Community on the Gregory River, the Wellesley Islands and seas connecting them to 
mainland, and parts of the mainland that have been designated Indigenous Protected Areas. By 
definition, native title is based on patterns of customary ownership of lands and waters. 

There are a variety of formal Indigenous management systems in the Southern Gulf catchments, 
including joint management of Lawn Hill Gorge, Boodjamulla National Park (Aboriginal Land) and 
the Indigenous Protected Areas of Thuwathu/Bujimulla (marine), Nijinda Durlga and Ganalanga-
Mindibirrina (see Figure 3-33). 




Aboriginal Lands, map
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Figure 3-31 Exclusive Aboriginal lands and pastoral interests make up the majority of the Southern Gulf catchments 




Native title map
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Figure 3-32 The extent of native title claims and determinations over the Southern Gulf catchments 




Protected areas
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Figure 3-33 Indigenous protected areas and other protected areas in the Southern Gulf catchments as of April 2020 

Data Source: Collaborative Australian Protected Areas Database (CAPAD) - (2020) from commonwealth, state and territory governments, non-
government organisations, Indigenous and other protected area managers. 

Augmenting the formal native title claims are registered ILUAs. ILUAs are voluntary registered 
agreements between native title claimants or holders and other interested parties to use and 
manage land and resources. ILUAs occur over 47.1% of the Southern Gulf catchments, and grazing 
and mining are the main land uses in these areas (see Figure 3-34). In addition to these formally 


registered and enduring native title areas are pastoral leases held by Indigenous Peoples and 
corporations, which confer rights under which land may be held and used. Pastoral leaseholders 
can include Traditional Owners and Indigenous residents, individually and in collective entities. 
The ownership of Lawn Hill and Riversleigh Pastoral Holding Company Pty Ltd was transferred to 
the Waanyi People under the Gulf Communities Agreement, which provided the native title 
approval for the development of the Century Mine. 



Indigenous Land Use Agreements, map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\6_Indigenous\4_S_Gulf\1_GIS\1_Map_docs\Indig_S_503_Registerd_ILUAs_v2.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 3-34 Indigenous Land Use Agreements (ILUAs) 

Total extent of all ILUAs is shown in pink. ILUAs cover a range of activities including the energy sector, industry 
(fishing) and local government. One single area may be covered by multiple ILUAs, only mining and pastoral ILUAs are 
highlighted by hatching. 


Over 50 ILUA arrangements exist in the Southern Gulf catchments; they relate to pastoralism, 
mining, conservation, commercial fishing, local shire business and energy infrastructure. ILUAs 
relating to pastoralism are most common, followed by mining. Mining ILUAs cover the greatest 
area at 24.2% of all ILUA types combined. Figure 3-34 shows the regions and types of practices 
that are related to the ILUAs. 

Indigenous population and residence 

The Indigenous population made up 27% of the total population of the Southern Gulf catchments 
in 2021 (Table 3-5). The 27% includes Indigenous Peoples who are part of the recognised local 
ownership groups identified above and residents who identify as Indigenous but have their origins 
elsewhere. Many Traditional Owners may primarily reside outside the traditional lands to which 
they have formal ties. These patterns of residence and dispersal reflect a combination of historical 
involuntary relocation, voluntary movement to seek jobs and other opportunities, and kinship and 
family links. As such, these administrative data do not account for the complexity of Indigenous 
Peoples’ social, linguistic and economic relations. Indigenous communities in the Southern Gulf 
catchments face a range of social and demographic challenges, including significant 
unemployment, poor health and housing, and structural impediments to economic participation, 
including remoteness and social and family units under high levels of stress. 

Approximately 60% of the population of the lower section of the Southern Gulf catchments 
identify as Indigenous. Mornington Island and Doomadgee residents are predominantly 
Indigenous Peoples, and they live in some of the Assessment area’s poorest townships 
(Everingham et al., 2013; see Table 3-5). High proportions of the population identify as Indigenous 
in several other settlements and outstations across the catchments. Only 21.4% of the population 
of the Mount Isa SA2 region identify as Indigenous (Table 3-5). 

A review of annual reports and a social impact assessment of the Century Mine (Carpentaria Land 
Council Aboriginal Corporation, 2021a; Carpentaria Land Council Aboriginal Corporation, 2022; 
Everingham et al., 2013) both stress the importance of creating local opportunities, including 
employment, capacity building for Indigenous owners and building assets on traditional lands. For 
instance, the Waanyi People acquired the Lawn Hill and Riversleigh cattle stations in 2020 under 
an arrangement with Century Mine. 

Indigenous governance and representation 

CLCAC and Queensland South Native Title Services (QSNTS) are the two major agencies 
representing Indigenous rights and interests within the Southern Gulf catchments. QSNTS mainly 
focuses on native title services. CLCAC has an economic development unit supporting PBCs to plan 
commercial opportunities and has an established land and sea ranger program. CLCAC 
collaborates with the Northern Land Council on the Waanyi Garawa Rangers working on the 
Waanyi Garawa Aboriginal Land Trust. Land-owning Indigenous groups form diverse organisational 
and political structures as part of their native title roles and economic development planning. In 
the southern region of the catchments, Kalkadoon Native Title Aboriginal Corporation RNTBC 
offers land and resource management and employment services to its members through its 
partnerships with businesses and stakeholders operating on its customary lands. PBCs and land 
councils can act for Traditional Owners with respect to Indigenous access, participation, 
partnerships and ownerships. 


Indigenous Peoples are formally involved in land and sea management through the Wellesley 
Islands Rangers, the Gangalidda-Garawa Rangers and within the two pastoral stations of Lawn Hill 
and Riversleigh. 

3.4.4 Indigenous water values and perspectives on development 

Indigenous water values 

Documentation of Indigenous oral histories across Australia demonstrate People’s connections to 
waters and lands and how water is a significant feature of Indigenous cultural landscapes (Martin 
and Trigger, 2015; Strang, 2005; Toussaint et al., 2005). Indigenous histories share a 
conceptualisation of water sources, rivers and lands as having been derived from the activities of 
mythic beings in Dreaming time (Barber and Jackson, 2011; Keen, 2003; Martin and Trigger, 2015; 
Morphy, 1991; Taçon, 2008). Dreaming necessitates sociocultural institutions and protocols that 
govern the use of water, determined by spiritual entities in the landscape (Martin and Trigger, 
2015; Morphy, 1991). Language place names are often strongly associated with places of fresh 
water and ancestral connections (Merlan, 1981; Trigger, 1987). In the Gulf Country, many 
Indigenous place names relate to freshwater sources (Martin and Trigger, 2015). Important places 
of water, waterholes and springs can also hold art sites of Rainbow Dreaming (Martin and Trigger, 
2015; Taçon, 2008). Dreaming connects People from the sea to inland regions, with recountings 
that tell of mythic beings adopting languages belonging to each territory and group (Martin and 
Trigger, 2015). 

Indigenous cultural heritage 

Indigenous cultural heritage relates to archaeological sites, places associated with traditional 
knowledge, and places of historical or contemporary significance. Aquatic places and systems 
strongly correlate with cultural heritage. Any development interests in these areas will likely affect 
places of cultural heritage significance and require negotiated conditions between Traditional 
Owners and leaseholders. Early scoping of cultural heritage conditions and requirements will aid 
consultations between development proponents and Traditional Owners. By way of illustration, 
the Lawn Hill and Riversleigh Pastoral Holding properties acquired by Waanyi People under an 
agreement with Century Mine are of significant cultural value (Everingham et al., 2013). Under the 
agreement, Century Mine preserves access rights for exploration with the mining company. In the 
southern part of the catchments, Kalkadoon Native Title Aboriginal Corporation RNTBC provides 
cultural heritage services in the mining and pastoral sectors. A priority of land-owning Indigenous 
groups of the Gulf Country is to have access rights to pastoral properties to sustain cultural 
heritage and customary values and roles (Memmott and Channells, 2014). 

Contemporary Indigenous water values 

Contemporary Indigenous water values stress the importance of secure water supply and good-
quality water for healthy landscapes and remote community health and livelihoods (Barber, 2013, 
2018; Barber and Woodward, 2018; Lyons and Barber, 2018). Indigenous water needs include 
cultural practices, pastoralism, tourism, hunting and fishing, agriculture and natural resource 
management. In the Southern Gulf catchments, Indigenous water values have been affected by 
the loss of language groups, dislocation from ancestral territories and pastoralism (Memmott and 
Channells, 2014). Indigenous involvement and ownership of pastoral leases across the catchments 


over the years have shifted how water is valued by groups and their members, with increasing 
emphasis on water places for pastoralism. The impact of many years of cattle grazing on the 
environment and Country has reshaped the relationship of Indigenous Peoples with water (Martin 
and Trigger, 2015; Scambary, 2013). Aboriginal corporations have negotiated access to water 
places for Traditional Owners to fish and hunt. The literature demonstrates that water supplies to 
significant Dreaming sites, and Indigenous perspectives and beliefs about underground water, 
remain critical to decisions about types of water harvesting techniques, their use and perceived 
impacts from long-term use (Martin and Trigger, 2015). 

Perspectives on water and irrigated agricultural development 

Traditional Owners and communities in the Southern Gulf catchments face increasing outside 
interest in irrigated agriculture and water extraction in their region (Carpentaria Land Council 
Aboriginal Corporation, 2022). Water monitoring is a priority in order to understand the impact of 
water-related development and threats that may affect Indigenous Peoples’ relationships with 
Country and community wellbeing. For example, CLCAC initiated a water quality monitoring 
program to gather baseline data and identify any impacts to fresh and saltwater systems caused 
by contamination, altered water flow and saltwater incursion into freshwater environments. The 
monitoring program was implemented with the Australian Rivers Institute, Griffith University, and 
included a capacity-building component. 

Regional land and water planning is an emerging priority for other Indigenous Peoples with rights 
and interests in the Southern Gulf catchments. They have concerns that water extraction for 
irrigation may adversely affect existing pastoral enterprises and Indigenous communities, as well 
as their future development options (Southern Gulf Natural Resource Management, 2016). 

Indigenous interests in water planning 

Water planning is understood as one way of managing water development risk and advancing 
sustainable management, but it also has challenges. The National Water Initiative guides and sets 
the goal for recognising Indigenous Peoples’ values and interests in water in terms of access and 
management. It considers Indigenous customary objectives, economic development interests, 
native title needs and Indigenous representation. The Water Plan (Gulf) 2007 is being renewed by 
the Queensland Government. Engagements are being facilitated with Indigenous Peoples through 
land councils and Aboriginal corporations. Recognising and incorporating Indigenous interests in 
contemporary water planning processes with competing water demands is challenging because of 
the limited knowledge of Indigenous Peoples’ interests and how to accommodate their 
perspectives. The involvement of Indigenous Peoples in water monitoring programs and their 
expressed concerns about different water extraction methods demonstrate their interest in 
maintaining sustainable supplies of good-quality water for diverse interests and values. 

3.4.5 Indigenous development objectives 

Exclusive native title determinations and large areas of Indigenous-owned land and ILUAs mean 
that communities in the Southern Gulf catchments have access to capital, land and resources. 
However, as a group, Indigenous Peoples in the study area remain socially and economically 
disadvantaged. 


Economic development is a key objective of Southern Gulf catchments Indigenous groups. This has 
been articulated in documents produced by the CLCAC, including its Strategic plan 2021–2025 
(Carpentaria Land Council Aboriginal Corporation, 2021b), annual reports (Carpentaria Land 
Council Aboriginal Corporation, 2021, 2022), PBC land and sea Country plans, Land and sea 
management 2014 (Carpentaria Land Council Aboriginal Corporation, 2014a, 2016a, 2016b), Social 
investment prospectus 2014 (Carpentaria Land Council Aboriginal Corporation, 2014b), Indigenous 
economic and business development opportunities in the Gulf of Carpentaria region (Carpentaria 
Land Council Aboriginal Corporation, 2013a), Carpentaria Land Councial Aboriginal Corporation 
destination and product development plan (Carpentaria Land Council Aboriginal Corporation, 
2013b). These documents provide details on Indigenous economic development goals. 

A key feature of Indigenous development objectives in the Assessment area is the diversity of 
development interests. These are broadly categorised into four key sectors (Carpentaria Land 
Council Aboriginal Corporation, 2021b): 

•resources
–mining rehabilitation and land management activities
–employment in mining operations
–asset acquisition and development



•land and sea management
–management of Indigenous Protected Areas
–carbon abatement
–fisheries compliance and monitoring



•pastoralism
–Lawn Hill and Riversleigh pastoral stations



•tourism
–ecotourism and Boodjamulla (Lawn Hill) National Park management (Gangalidda andGarawa Native Title Aboriginal Corporation, 2014; Carpentaria Land Council AboriginalCorporation, 2021; Queensland Parks and Wildlife Service, 2022)
–ecotourism and business development opportunities (particularly proposals thatacknowledge the role of the Waanyi People as traditional custodians, respect their loreand culture, and provide opportunities for the Waanyi People to improve social andeconomic outcomes. This is a core objective of the Waanyi Strategic plan 2020–2025(Waanyi Native Title Aboriginal Corporation RNTBC, 2020) and can potentially improve thesocial and economic outcomes for the Waanyi People
–GRAC Birri Fishing Lodge on Mornington Island (which could be re-established as a viabletourism entity)



•service delivery
–Jigija Indigenous Fire Training Program of the Indigenous-owned business Gangalidda andGarawa Services Pty Ltd (Gangalidda and Garawa Native Title Aboriginal Corporation(GGNTAC)), which provides fire management and mitigation training in the traditionalCountry of the Gangalidda People.






These sectors represent a continued focus on supporting a strong, sustainable region. Expanding 
sustainable economic opportunities that mobilise Traditional Owners’ values, interests and rights 
broadly across the Assessment area requires partnership and collaboration. The CLCAC Economic 
Development and Business Support Unit has a role in enabling, generating and sustaining a wide 
range of opportunities. It works with its partners, stakeholders and the community to benefit the 
Southern Gulf catchment’s People and communities (Carpentaria Land Council Aboriginal 
Corporation, 2021b). 

Partnerships and planning 

Indigenous Peoples in the Southern Gulf catchments possess diverse natural, historical and 
cultural assets. Indigenous corporations such as CLCAC and Kalkadoon Native Title Aboriginal 
Corporation RNTBC have established partnerships across the private, government, non-
government and research sectors. For example, there are partnerships with: 

•Century Mine under the Gulf Communities Agreement
•universities for marine and water-related ecosystem monitoring and research
•Indigenous and non-Indigenous pastoralists
•natural resource management agencies, including Southern Gulf NRM.


3.5 Legal and policy environment 

Proponents must be aware of a range of legal, policy and regulatory requirements and approvals 
when contemplating land and water developments within the Southern Gulf catchments. As part 
of their due diligence process, proponents must be prepared to secure appropriate land tenure 
and authorisations to take water and to obtain the necessary approvals well in advance of 
commencing construction and operation of a development. This section describes the overarching 
Australian legal context and summarises the key issues and related legal, regulatory and approval 
considerations that apply to water-related developments in the Southern Gulf catchments. 
Detailed information is available in the companion technical reports on water planning 
arrangements (Vanderbyl, 2024) and regulatory requirements for land and water development 
(Speed and Vanderbyl, 2024). 

3.5.1 Australian legal and policy context 

Australia is a federal constitutional monarchy consisting of six states and two territories. The 
Southern Gulf catchments straddle the border between Queensland and the NT, as shown in 
Figure 3-30. 

There are three levels of government: the Australian Government, state and territory 
governments, and local governments. The Australian Government has powers under the EPBC Act 
relating to matters of national environmental significance (including those arising from the World 
Heritage Convention, the Ramsar Convention on Wetlands of International Importance, and the 
Convention on Biological Diversity) and powers relating to the native title rights of Indigenous 
Peoples. 


Generally, the states and territories are responsible for land, water and environmental policy and 
laws. However, the NT is an administrative territory established by the Australian Government 
rather than a state. This means that, although it has been given similar powers to the states, the 
Australian Parliament retains a right of veto over all NT laws. 

Local governments are established within the states and territories and usually have responsibility 
for land use planning, which involves establishing local planning schemes that regulate land use 
and development. However, the planning system in the NT is administered by the NT Government 
rather than by local government. 

Laws made by the Australian Government will generally apply to activities in both the NT and 
Queensland. Laws made by the NT and Queensland governments, or local laws passed by a local 
government, will only be applicable within the relevant jurisdiction. 

3.5.2 Key legal and regulatory requirements 

Land tenure and native title 

Proponents will need to secure appropriate tenure over the land of the proposed development 
site. Consideration should be given as to whether land tenure can be granted or transferred to the 
developer (or converted to a more suitable form of tenure) and whether any approvals will be 
required beyond those held by the current owner or lessee of the land. 

If the land is not freehold, native title requirements are likely to apply. In that case, the proponent 
will need to check if a native title determination has been made (or is underway) for the land, who 
the relevant parties are and whether the proposed development is consistent with the rights of 
native title holders. The proponent will then need to negotiate with the relevant native title 
holders for the area prior to undertaking development activities. 

If the proposed development is on Aboriginal freehold land in the NT, the proponent will need to 
obtain the consent of the Traditional Owners and approval from the relevant Aboriginal Land 
Council. If the proposed development is on pastoral lease land in the NT, the proponent will 
require approval for non-pastoral uses from the Pastoral Land Board. If the proposed development 
is on state land (including leasehold land) within Queensland, the proponent will need to comply 
with the requirements of the Queensland Land Act 1994. 

Authority to take water 

Proponents will need to secure an appropriate entitlement to take any water that may be required 
to construct and operate the development. An entitlement will usually be required to take surface 
water or groundwater. In the NT, this is likely to be in the form of a water licence, while in 
Queensland this would usually be either a water licence or a water allocation. 

Water entitlements may be purchased and transferred from an existing entitlement holder subject 
to state or territory requirements or constraints relating to water trading and the purpose of the 
water use. Alternatively, it may be possible to seek the grant of a new water entitlement from 
unallocated water reserves. In Queensland, water trading requirements and unallocated water 
reserves provisions are set out in the Water Plan (Gulf) 2007 (Figure 3-30) and its associated water 
management protocol. In the NT, such requirements are typically set out in water allocation plans. 


However, no such plans are currently applicable to that part of the Southern Gulf catchment, so 
options for securing water are limited. 

Planning requirements 

Proponents will need to ensure that their development will be consistent with local and state or 
territory planning requirements. This usually involves a formal application and assessment 
process. 

A single planning scheme applies across the NT, under which a proposed development may be 
categorised as: (i) permitted, (ii) merit assessable, (iii) impact assessable, or (iv) prohibited. NT 
Government websites provide detailed checklists and criteria for helping a proponent to 
determine the category applicable to their development proposal. A development permit will be 
required for developments categorised as merit assessable and impact assessable. In addition, the 
NT Planning Commission may prepare a significant development report to be considered in the 
assessment of the development permit where a proponent’s development is over a certain 
investment threshold. 

In Queensland, a proponent will require a development permit for any activities that are 
‘assessable development’ under a planning scheme or planning instrument. The development 
assessment process is coordinated in the case of matters of state interest, including vegetation 
clearing and the granting of environmental authorities. In some instances a development may be 
able to obtain an ‘infrastructure designation’ under the Queensland Planning Act 2016, which 
would remove the need for a development permit for some activities. In addition, a proponent will 
require a regional interests development approval for broadacre cropping or water storage within 
a strategic environmental area. 

Environmental approvals 

Proponents will need to obtain approvals for certain activities that have a potential environmental 
impact, including any building or construction activities. 

A proponent may require federal environmental approval under the EPBC Act if a development 
has the potential to affect matters of national environmental significance. Federal environmental 
impact assessment requirements can be met through the NT or Queensland governments’ 
assessment processes, allowing for a more streamlined assessment process. However, the 
ultimate decision under the EPBC Act remains with the Australian Minister for the Environment 
and Water. 

In the NT, a proponent will require environmental approval for any actions that will have a 
significant impact on the environment or that are captured under a ‘referral trigger’. Where 
required, the NT Environment Protection Authority will undertake an environmental impact 
assessment. Such processes can take significant time to complete. 

Under Queensland law, a proponent will require environmental approval for an ‘environmentally 
relevant activity’, which may require an environmental impact statement. The application process 
is under the Queensland Planning Act development assessment framework. 


Cultural heritage 

Proponents will need to identify potential cultural heritage sites and/or objects (including 
Indigenous cultural heritage sites and/or objects) if a proposed development will affect cultural 
heritage at a federal and state or territory level. 

The proponent will need to undertake searches of the NT Heritage Register, the NT Aboriginal 
Areas Protection Authority register of sacred sites, the Queensland Heritage Register and the 
Queensland Cultural Heritage Register. 

National heritage values will also need to be considered through an environmental impact 
assessment process under the EPBC Act. A cultural heritage management plan is advisable (and 
may be required) for significant developments. 

Works in a watercourse 

Proponents will need approval to undertake any activities within a watercourse. 

In the NT, a proponent will require a permit under the Northern Territory Water Act 1992 to 
interfere with a watercourse (e.g. extraction of materials, construction within a waterway, or 
diversion of a watercourse). 

In Queensland, a proponent will require a permit under the Queensland Water Act 2000 to 
interfere with a watercourse, including for the construction of a barrier and the removal of 
vegetation or quarry material. 

Clearing vegetation 

Proponents will require approval to clear native vegetation to allow for construction or farming or 
other agricultural activities. Exemptions may apply for routine maintenance and day-to-day 
management activities. 

In the NT, restrictions apply to both freehold land (including Aboriginal freehold land) and pastoral 
leases. For clearing on pastoral land, permit applications are determined by the Pastoral Land 
Board. For freehold land, applications are assessed under the NT Planning Act 1999 and must be 
lodged with the Department of Infrastructure, Planning and Logistics. 

In Queensland, clearing of vegetation is generally captured as assessable development and will 
require a development permit under the Queensland Planning Act 2016. 

 


3.6 References 

29Metals (2022) Capricorn Copper. Viewed 24 February 2024, Hyperlink to: Capricorn Copper
. 

29Metals (2024) Mineral resources and ore reserves. Viewed 24 February 2024 Hyperlink to: Mineral resources and ore reserves
. 

ABARES (2022) Land use data download – Land use of Australia 2010–11 to 2015–16, 250 m 
[dataset]. Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra. 
Viewed 20 December 2023, Hyperlink to: Land use data download
. 

ABC (8 September 2005) Xstrada lead mine to close in December. Australian Broadcasting 
Corporation. Viewed 17 February 2024, Hyperlink to: Xstrada lead mine to close in December
. 

ABS (2006) Census of population and housing time series profile. Catalogue number 2003.0 for 
various Statistical Area regions falling partly within Southern Gulf catchments. Australian 
Bureau of Statistics website. Viewed 29 October 2023, Hyperlink to: ABS Census website
. 

ABS (2011) Census of population and housing time series profile. Catalogue number 2003.0 for 
various Statistical Area regions falling partly within Southern Gulf catchments. Australian 
Bureau of Statistics, Canberra. Viewed 29 October 2023, Hyperlink to: ABS Census website
. 

ABS (2016) Census of population and housing time series profile. Catalogue number 2003.0 for 
various SA regions falling partly within Southern Gulf catchments. Australian Bureau of 
Statistics website. Viewed 29 October 2023, Hyperlink to: ABS Census website
. 

ABS (2021b) Census of population and housing time series profile. Catalogue number 2003.0 for 
various SA regions falling partly within the Southern Gulf catchments. Australian Bureau of 
Statistics, Canberra. Viewed 29 October 2023, Hyperlink to: ABS Census website
. 

ABS (2021a) Census of Carpentaria Aboriginal and/or Torres Strait Islander people. Australian 
Bureau of Statistics, Canberra. Viewed 7 December 2023, https://www.abs.gov.au/census. 

ABS (2021c) Mount Isa 2021 Census community profiles – Working population profile [dataset], 
Australian Bureau of Statistics, Canberra. Viewed 18 February 2024, Hyperlink to: Mount Isa 2021 Census community profiles
. 

ABS (2022) Value of agricultural commodities produced, Australia, 2020–21. Australian Bureau of 
Statistics website. Viewed 29 October 2023, Hyperlink to: Value of agricultural commodities produced, Australia, 2020–21
. 

ABS (2023) Socio-Economic Indexes for Area (SEIFA) Australia, 2021 (Released 27 April 2023). 
Australian Bureau of Statistics, Canberra. Viewed 25 September 2023, Hyperlink to: Socio-Economic Indexes for Area (SEIFA) Australia, 2021
. 

ACARA (2023) My School. My School website. Australian Curriculum, Assessment and Reporting 
Authority, Sydney. Viewed 13 September 2023, Hyperlink to: My School website
. 


AEMO (2023) The National Electricity Market. Fact sheet. Australian Energy Market Operator. 
Viewed 17 January 2024, Hyperlink to: The National Electricity Market
. 

Australian Energy Regulator (2021) Pipeline capacity trading: two year review. AER, Canberra. Hyperlink to: Pipeline capacity trading: two year review
. 

Amelung B and Nicholls S (2014) Implications of climate change for tourism in Australia. Tourism 
Management 41, 228–244. Hyperlink to: Implications of climate change for tourism in Australia
. 

André J and Waterson L (13 October 2023) North West Phosphate begins mining Paradise South in 
outback Queensland amid global demand for fertiliser, renewables. ABC North West 
Queensland. Viewed 23 February 2024, Hyperlink to: North West Phosphate begins mining Paradise South in outback Queensland amid global demand for fertiliser, renewables
. 

APA (2022) Diamantina Power Station. APA Group. Viewed 17 January 2024, Hyperlink to: Diamantina Power Station
. 

Atlas of Living Australia (2023a) Atlas of Living Australia: Mornington Island occurrence download 
at https://doi.org/10.26197/ala.070e61f4-73a4-437f-a15e-ef9f305c7df8 accessed on 8 
November 2023. 

Atlas of Living Australia (2023b) Atlas of Living Australia: Southern Gulf occurrence download at 
https://doi.org/10.26197/ala.53e3a9bb-e2f1-428f-87c2-ec30b38e8f09 accessed on 13 
September 2023. 

Australian Fisheries (1975) Prawn farm closed despite successes. Australian Fisheries 34(7), 21–22. 

Australian Indigenous Australians Agency (2023) Environment. Viewed 18 March 2024, 
https://www.niaa.gov.au/our-work/environment-and-land. 

Barber M (2013) Indigenous water values, rights and interests in the Flinders and Gilbert 
catchments. A technical report to the Australian Government from the CSIRO Flinders and 
Gilbert Agricultural Resource Assessment, part of the North Queensland Irrigated Agriculture 
Strategy. CSIRO Water for a Healthy Country and Sustainable Agriculture flagships, Australia. 

Barber M (2018) Indigenous water values, rights, interests and development objectives in the 
Darwin catchments. A technical report to the Australian Government from the CSIRO 
Northern Australia Water Resource Assessment, part of the National Water Infrastructure 
Development Fund: Water Resource Assessments. CSIRO, Canberra. Hyperlink to: Indigenous water values, rights, interests and development objectives in the Darwin catchments
. 

Barber M and Jackson S (2011) Water and Indigenous People in the Pilbara, Western Australia: a 
preliminary study. CSIRO, Darwin. Viewed 18 March 2024, 
https://www.academia.edu/49389081/Water_and_Indigenous_People_in_the_Pilbara_Western_Australia_A_Preliminary_Study. 

Barber M and Jackson S (2014) Autonomy and the intercultural: interpreting the history of 
Australian Aboriginal water management in the Roper River catchment, Northern Territory. 


Journal of the Royal Anthropological Institute 20(4), 670–693. 

Barber M and Woodward E (2018). Indigenous water values, rights, interests and development 
objectives in the Fitzroy catchment. A technical report to the Australian Government from 
the CSIRO Northern Australia Water Resource Assessment, part of the National Water 
Infrastructure Development Fund: Water Resource Assessments. CSIRO, Canberra. Hyperlink to: Indigenous water values, rights, interests and development objectives in the Fitzroy catchment
. 

Barker RD and Vestjens WJM (1990) The food of Australian birds: 1. Non-passerines. CSIRO 
Division of Wildlife and Ecology, Canberra. 

Bayliss P, Buckworth R and Dichmont C (2014) Assessing the water needs of fisheries and 
ecological values in the Gulf of Carpentaria. Final report prepared for the Queensland 
Department of Natural Resources and Mines. CSIRO, Australia. 

Bishop K (1980) Fish kills in relation to physical and chemical changes in Magela Creek (East 
Alligator River system, Northern Territory) at the beginning of the tropical wet season. 
Australian Zoologist 20, 485–500. 

Bowen MK, Chudleigh F and Perry L (2020) Northern Downs beef production systems: preparing 
for, responding to, and recovering from drought. Queensland Department of Agriculture and 
Fisheries, Queensland, Brisbane. 

Bowen MK, Chudleigh F, Rolfe JW and English B (2019) Northern Gulf beef production systems: 
preparing for, responding to, and recovering from drought. Queensland Department of 
Agriculture and Fisheries, Queensland, Brisbane. 

Broadley A, Stewart‐Koster B, Kenyon RA, Burford MA and Brown CJ (2020) Impact of water 
development on river flows and the catch of a commercial marine fishery. Ecosphere 11(7), 
e03194. Hyperlink to: Impact of water development on river flows and the catch of a commercial marine fishery
. 

Brodie JE and Mitchell AW (2005) Nutrients in Australian tropical rivers: changes with agricultural 
development and implications for receiving environments. Marine and Freshwater Research 
56(3), 279–302. Hyperlink to: Nutrients in Australian tropical rivers: changes with agricultural development and implications for receiving environments
. 

Buckley KA, Smith LDG, Crook DA, Pillans RD and Kyne PM (2020) Conservation impact scores 
identify shortfalls in demonstrating the benefits of threatened wildlife displays in zoos and 
aquaria. Journal of Sustainable Tourism 28(7), 978-1002. Hyperlink to: Conservation impact scores identify shortfalls in demonstrating the benefits of threatened wildlife displays in zoos and aquaria
. 

Buckworth RC, Venables WN, Lawrence E, Kompas T, Pascoe S, Chu L, Hill F, Hutton T and 
Rothlisberg PC (2014) Incorporation of predictive models of banana prawn catch for MEY-
based harvest strategy development for the Northern Prawn Fishery. Final report to the 
Fisheries Research and Development Corporation, Project 2011/239. CSIRO Marine and 
Atmospheric Research, Brisbane. 

Bugno M and Polonsky M (2024) The tyranny of time and distance: impediments for remote 
agritourism operators accessing support in the Northern Territory, Australia. Tourism 
Planning & Development 21(2), 200–222. Hyperlink to: The tyranny of time and distance: impediments for remote agritourism operators accessing support in the Northern Territory
. 


Bunn SE and Arthington AH (2002) Basic principles and ecological consequences of altered flow 
regimes for aquatic biodiversity. Environmental Management 30(4), 492–507. Hyperlink to: Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity
. 

Burford MA, Valdez D, Curwen G, Faggotter JS, Ward DP and O’Brien KR (2016) Inundation of 
saline supratidal mudflats provides an important source of carbon and nutrients in an 
aquatic system. Marine Ecology Progress Series 545, 21–33. Hyperlink to: Inundation of saline supratidal mudflats provides an important source of carbon and nutrients in an aquatic system
. 

Canham CA, Duvert C, Beesley LS, Douglas MM, Setterfield SA, Freestone FL, Clohessy S and 
Loomes RC (2021) The use of regional and alluvial groundwater by riparian trees in the wet‐
dry tropics of northern Australia. Hydrological Processes 35(5), e14180. Hyperlink to: The use of regional and alluvial groundwater by riparian trees in the wet‐dry tropics of northern Australia
. 

Carpentaria Land Council Aboriginal Corporation (2013a) Indigenous economic and business 
development opportunities in the Gulf of Carpentaria. CLCAC. Viewed 18 March 2024, 
https://www.clcac.com.au/sites/default/files/downloads/clcac_economic_development_summary_report_2013.pdf. 

Carpentaria Land Council Aboriginal Corporation (2013b) Destination and product development 
plan. CLCAC. Viewed 18 March 2024, 
https://www.clcac.com.au/sites/default/files/downloads/clcac_destination_and_product_development_plan_201306.pdf. 

Carpentaria Land Council Aboriginal Corporation (2014a) Land and sea management. CLCAC. 
Viewed 18 March 2024, 
https://www.clcac.com.au/sites/default/files/downloads/clcac_land-sea_management.pdf. 

Carpentaria Land Council Aboriginal Corporation (2014b) Social investment prospectus. CLCAC. 
Viewed 18 March 2024, https://www.clcac.com.au/publications/2014/51. 

Carpentaria Land Council Aboriginal Corporation (2016a) Nijinda Durlga (Gangalidda) Indigenous 
Protected Area management plan. Prepared by Carpentaria Land Council Aboriginal 
Corporation on behalf of the Gangalidda People. Viewed 18 March 2024, 
https://www.clcac.com.au/sites/default/files/downloads/gangalidda_ipa_management_plan_web_ready.pdf. 

Carpentaria Land Council Aboriginal Corporation (2016b) Thuwathu/Bujimulla Indigenous 
Protected Area management plan. Prepared by Carpentaria Land Council Aboriginal 
Corporation on behalf of the Traditional Owners of the Wellesley Islands. Viewed 18 March 
2024, 
https://www.clcac.com.au/sites/default/files/downloads/wellesly_islands_ipa_management_plan_web_ready_0.pdf. 

Carpentaria Land Council Aboriginal Corporation (2021) Annual report 2020–2021. CLCAC. Viewed 
18 March 2024, 
https://www.clcac.com.au/sites/default/files/downloads/clcac_annualreport_2020_21_final_.pdf. 

Carpentaria Land Council Aboriginal Corporation (2021b) Strategic plan 2021–2025. CLCAC. 
Viewed 18 March 2024, 


https://www.clcac.com.au/sites/default/files/downloads/clcac_strategic_plan_2021-
25_final_dp_web.pdf. 

Carpentaria Land Council Aboriginal Corporation(2022) Annual report 2021–2022. CLCAC. Viewed 
18 March 2024, Hyperlink to: Annual report 2021–2022
. 

Close P, Bartolo R, Pettit N, Ward D and Kennard M (2015) Vulnerability and risk assessment of 
northern Australian catchments and biodiversity. Climate Change Adaptation across 
Australia’s Monsoonal North – Northern Monsoon NRM Cluster, Griffith University, Nathan. 

Close P, Wallace J, Bayliss P, Bartolo R, Burrows D, Pusey B, Robinson C, McJannet D, Karim F and 
Byrne G (2012) Assessment of the likely impacts of development and climate change on 
aquatic ecological assets in Northern Australia. A report for the National Water Commission, 
Australia. Tropical Rivers and Coastal Knowledge (TRaCK) Commonwealth Environmental 
Research Facility. Charles Darwin University, Darwin. 

Cobcroft J, Bell R, Fitzgerald J, Diedrich A and Jerry D (2020) Northern Australia aquaculture 
industry situational analysis, Project. A.1.1718119. Cooperative Research Centre for 
Developing Northern Australia (CRCNA). 

Compagno LJV, Cook SF, Oetinger MI and Fowler SL (2006) Anoxypristis cuspidata. The IUCN Red 
List of Threatened Species. 

Corriveau A, Klaassen M, Garnett ST, Kaestli M, Christian K, Crewe TL, Loewensteiner DA and 
Campbell HA (2022) Seasonal space use and habitat selection in magpie geese: implications 
for reducing human-wildlife conflicts. Journal of Wildlife Management 86(7), e22289. Hyperlink to: Seasonal space use and habitat selection in magpie geese: implications for reducing human-wildlife conflicts
. 

Cotin J, García-Tarrasón M, Sanpera C, Jover L and Ruiz X (2011) Sea, freshwater or saltpans? 
Foraging ecology of terns to assess mercury inputs in a wetland landscape: The Ebro Delta. 
Estuarine, Coastal and Shelf Science 92(1), 188–194. Hyperlink to: Sea, freshwater or saltpans? Foraging ecology of terns to assess mercury inputs in a wetland landscape: The Ebro Delta
. 

Cowley T (2014) The pastoral industry survey – Katherine region. NT Department of Primary 
Industry and Fisheries, Australia. 

Craig LS, Olden JD, Arthington AH, Entrekin S, Hawkins CP, Kelly JJ, Kennedy TA, Maitland BM, Rosi 
EJ, Roy AH, Strayer DL, Tank JL, West AO and Wooten MS (2017) Meeting the challenge of 
interacting threats in freshwater ecosystems: a call to scientists and managers. Elementa: 
Science of the Anthropocene 5(72). Hyperlink to: Meeting the challenge of interacting threats in freshwater ecosystems: a call to scientists and managers
. 

Crook DA, Buckle DJ, Morrongiello JR, Allsop QA, Baldwin W, Saunders TM and Douglas MM (2020) 
Tracking the resource pulse: movement responses of fish to dynamic floodplain habitat in a 
tropical river. Journal of Animal Ecology 89(3), 795–807. Hyperlink to: Tracking the resource pulse: movement responses of fish to dynamic floodplain habitat in a tropical river
. 

Crook DA, Lowe WH, Allendorf FW, Erős T, Finn DS, Gillanders BM, Hadweng WL, Harrod C, 
Hermoso V, Jennings S, Kilada RW, Nagelkerken I, Hansen MM, Page TJ, Riginos C, Fry B and 
Hughes JM (2015) Human effects on ecological connectivity in aquatic ecosystems: 
integrating scientific approaches to support management and mitigation. Science in the 
Total Environment 534(2015), 52–64. Hyperlink to: Human effects on ecological connectivity in aquatic ecosystems: integrating scientific approaches to support management and mitigation
. 


Dambacher JM, Rothlisberg PC and Loneragan NR (2015) Qualitative mathematical models to 
support ecosystem-based management of Australia’s Northern Prawn Fishery. Ecological 
Applications 25(1), 278–298. Hyperlink to: Qualitative mathematical models to support ecosystem-based management of Australia’s Northern Prawn Fishery
. 

Department of Agriculture‚ Water and the Environment (2020a) Collaborative Australian Protected 
Areas Database (CAPAD) 2020 Marine. Viewed 18 September 2024, 
https://www.dcceew.gov.au/environment/land/nrs/science/capad/2020. 

Department of Agriculture‚ Water and the Environment (2020b) Collaborative Australian 
Protected Areas Database (CAPAD) 2020 Terrestrial. Viewed 18 September 2024, 
https://www.dcceew.gov.au/environment/land/nrs/science/capad/2020. 

Department of Agriculture‚ Water and the Environment (2021a) Directory of Important Wetlands 
in Australia. Viewed 08 December 2023, 
https://www.environment.gov.au/water/wetlands/australian-wetlands-database/directory-
important-wetlands. 

Department of Agriculture‚ Water and the Environment (2021b) EPBC Act Protected Matters 
Report: Southern Gulf catchments. Viewed 19 September 2023, https://pmst.awe.gov.au/. 

Department of Climate Change‚ Energy‚ the Environment and Water (2020) National Vegetation 
Information System (NVIS) v6.0. Viewed 19 January 2024, Hyperlink to: National Vegetation Information System
. 

Department of the Environment and Energy (2010) Directory of Important Wetlands in Australia 
(DIWA). Viewed 08 December 2023, 
https://www.environment.gov.au/water/wetlands/australian-wetlands-database. 

Department of Environment and Science (2023) WildNet wildlife records - published - Queensland, 
Viewed 28 November 2023. 

Department of Environment Parks and Water Security (2019) Fauna Atlas N.T. accessed on 28 
November 2023. 

Dias MP, Lecoq M, Moniz F and Rabaça JE (2014) Can human-made saltpans represent an 
alternative habitat for shorebirds? Implications for a predictable loss of estuarine sediment 
flats. Environmental Management 53(1), 163–171. Hyperlink to: Can human-made saltpans represent an alternative habitat for shorebirds?
. 

Dichmont CM, Deng A, Punt AE, Ellis N, Venables WN, Kompas T, Ye Y, Zhou S and Bishop J (2008) 
Beyond biological performance measures in management strategy evaluation: bringing in 
economics and the effects of trawling on the benthos. Fisheries Research 94, 238–250. Hyperlink to: Beyond biological performance measures in management strategy evaluation
. 

Douglas MM, Bunn SE and Davies PM (2005) River and wetland food webs in Australia’s wet–dry 
tropics: general principles and implications for management. Marine and Freshwater 
Research 56(3), 329–342. Hyperlink to: River and wetland food webs in Australia’s wet–dry tropics
. 

Duke NC, Field C, Mackenzie JR, Meynecke J-O and Wood AL (2019) Rainfall and its possible 
hysteresis effect on the proportional cover of tropical tidal-wetland mangroves and 
saltmarsh–saltpans. Marine and Freshwater Research 70(8), 1047–1055. Hyperlink to: Rainfall and its possible hysteresis effect on the proportional cover of tropical tidal-wetland mangroves and saltmarsh–saltpans
. 


Duke NC, Kovacs JM, Griffiths AD, Preece L, Hill DJ, Van Oosterzee P, Mackenzie J, Morning HS and 
Burrows D (2017) Large-scale dieback of mangroves in Australia’s Gulf of Carpentaria: a 
severe ecosystem response, coincidental with an unusually extreme weather event. Marine 
and freshwater research 68(10), 1816–1829. Hyperlink to: Large-scale dieback of mangroves in Australia’s Gulf of Carpentaria
. 

Dulvy N, Davidson, LNK, Kyne, PM, Simpfendorfer, CA, Harrison, LR, Carlson, JK, and Fordham, SV, 
(2016) Ghosts of the coast: global extinction risk and conservation of sawfishes. Aquatic 
Conservation: Marine and Freshwater Ecosystems 26(1), 134-153. Hyperlink to: Ghosts of the coast: global extinction risk and conservation of sawfishes
. 

Ebner BC, Millington M, Holmes BJ, Wilson D, Sydes T, Bickel TO, Power T, Hammer M, Lach L, 
Schaffer J, Lymbery A and Morgan DL (2020) Scoping the biosecurity risks and appropriate 
management relating to the freshwater ornamental aquarium trade across northern 
Australia. Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER) 
Publication 20/17, James Cook University, Cairns. 

Ebner BC, Morgan DL, Kerezsy A, Hardie S, Beatty SJ, Seymour JE, Donaldson JA, Linke S, Peverell S, 
Roberts D, Espinoza T, Marshall N, Kroon F, Burrows D and McAllister R (2016) Enhancing 
conservation of Australian freshwater ecosystems: identification of freshwater flagship 
fishes and relevant target audiences. Fish and Fisheries 17(4), 1134–1151. Hyperlink to: Enhancing conservation of Australian freshwater ecosystems
. 

Everingham J, Barnes R and Brereton D (2013) Gulf Communities Agreement 2008–2013. 15-year 
Review. Centre for Social Responsibility in Mining, The University of Queensland, Brisbane. 

Evolution Mining (2023) Fact Sheet FY23 – Ernest Henry operation. Viewed 23 February 2024, Hyperlink to: Fact Sheet FY23 – Ernest Henry operation
. 

Finlayson C, Storrs M, Hall R and Bayliss B (1999) Management issues for northern Australian 
wetlands. In: Finlayson CM and Spiers AG (eds) A compendium of information for managing 
and monitoring wetlands in tropical Australia. Supervising Scientist Report 148. Supervising 
Scientist, Canberra, 143–167. 

Finn M and Jackson S (2011) Protecting Indigenous values in water management: a challenge to 
conventional environmental flow assessments. Ecosystems 14(8), 1232–1248. Hyperlink to: Protecting Indigenous values in water management
. 

Frith HJ and Davies SJJF (1961) Ecology of the magpie goose, Anseranas semipalmata Latham 
(Anatidae). CSIRO Wildlife Research 6(2), 91–141. Hyperlink to: Ecology of the magpie goose, Anseranas semipalmata Latham (Anatidae)
. 

Fry G, Laird, A. and Lawrence, E. (2021) Monitoring interactions with bycatch species using crew-
member observer data collected in the Northern Prawn Fishery: 2017–2019. Final Report to 
Australian Fisheries Management Authority, R2017/0835. CSIRO, Australia. 

Fuller D, Buultjens J and Cummings E (2005) Ecotourism and indigenous micro-enterprise 
formation in northern Australia opportunities and constraints. Tourism Management. Hyperlink to: Ecotourism and indigenous micro-enterprise formation in northern Australia opportunities and constraints
. 

Gangalidda and Garawa Native Title Aboriginal Corporation (2014) Garawa land and sea country 
plan. Viewed 18 March 2024, 
https://www.clcac.com.au/sites/default/files/downloads/clcac_garawa_land_sea_country_plan_web_version_50dpi.pdf. 


Garnett ST, Duursma DE, Ehmke G, Guay P-J, Stewart A, Szabo JK, Weston MA, Bennett S, Crowley 
GM, Drynan D, Dutson G, Fitzherbert K and Franklin DC (2015) Biological, ecological, 
conservation and legal information for all species and subspecies of Australian bird. Scientific 
Data 2(1), 150061. Hyperlink to: https://doi.org/10.1038/sdata.2015.61
. 

Geological Survey of Queensland (2024) Mineral Occurrence Database (MINOCC). Queensland 
Government. Viewed 8 March 2024, https://geoscience.data.qld.gov.au/dataset/ds000004. 

Geoscience Australia (2017) GEODATA TOPO 250K Series 3 Topographic Data. Viewed 
1 October 2023, http://pid.geoscience.gov.au/dataset/ga/64058. 

Glencore (2023a) Mount Isa Mines operational changes. Media statement 18 October 2018. 
Viewed 25 July 2023, Hyperlink to: Mount Isa Mines operational changes. Media statement
. 

Glencore (2023b) Glencore latest publications – financial statements and operational reports. 
Viewed 21 December 2023, Hyperlink to: Glencore latest publications – financial statements and operational reports
. 

Glencore (2023c) Operational changes – Queensland metals. Viewed 10 January 2024, Hyperlink to: Operational changes – Queensland metals
. 

Graham P, Hayward J and Foster J (2023). GenCost 2023–24: consultation draft. CSIRO, Australia. 
DOI: 10.25919/xxd6-qz89. 

Greiner R (2010) Improving the net benefits from tourism for people living in remote northern 
Australia. Sustainability 2(7) 2197–2218. Hyperlink to: Improving the net benefits from tourism for people living in remote northern Australia
. 

Hadwen WL, Arthington AA, Boon PI, Taylor B and Fellows CS (2011) Do climatic or institutional 
factors drive seasonal patterns of tourism visitation to protected areas across diverse 
climate zones in eastern Australia? Tourism Geographies 13(2), 187–208. Hyperlink to: Do climatic or institutional factors drive seasonal patterns of tourism visitation to protected areas across diverse climate zones in eastern Australia?
. 

Hayward J (2024) Potential for farm-scale hybrid renewable energy supply options in the Victoria 
and Southern Gulf catchments. A technical report from the CSIRO Victoria and Southern Gulf 
Water Resource Assessments for the National Water Grid. CSIRO, Australia. 

HERE Technologies (2021) Traffic products. NAVIGATE. Viewed 15 February 2023, Hyperlink to: Traffic products web page
. 

Hermoso V, Ward DP and Kennard MJ (2013) Prioritizing refugia for freshwater biodiversity 
conservation in highly seasonal ecosystems. Diversity and Distributions 19(8), 1031–1042. Hyperlink to: Prioritizing refugia for freshwater biodiversity conservation in highly seasonal ecosystems
. 

Higgins A, McFallan S, Laredo L, Prestwidge D and Stone P (2015) TRANSIT– a model for simulating 
infrastructure and policy interventions in agriculture logistics: application to the northern 
Australia beef industry. Computers and Electronics and Agriculture, 114, 32–42. Hyperlink to: TRANSIT– a model for simulating infrastructure and policy interventions in agriculture logistics
. 

Incitec Pivot (n.d.) Phosphate Hill – Working with us. Viewed 23 February 2024, 
https://www.incitecpivot.com.au/siteassets/document-centre/work-with-
us/phosphate_hill_leaflet.pdf 


Integration and Application Network (2023) Integration and Application Network 
(ian.umces.edu/media-library). Attribution-ShareAlike 4.0 International (CC BY-SA 4.0). 
Victoria catchment icons. Bos taurus, Penaeus monodon adult: Jane Hawkey; Corymbia spp, 
Melaleuca rhaphiophylla, Generic tree rainforest 3, Avicennia germinans, Macropus 
fuliginosus, Pluvialis fulva, trawler: Tracey Saxby; Pennisetum ciliare, Eucalyptus 
camaldulensis: Kim Kraeer and Lucy Van Essen-Fishman; Lates calcarifer, Carcharhinus leucas 
(bull shark) 2: Dieter Tracey; Haematopus longirostris (pied oystercatcher): Jane Thomas. 
Viewed 29 September 2021, https://ian.umces.edu/media-library/symbols/#overview. 

Jackson D, Rolfe JW, English BH, Holmes B, Matthews R, Dixon RM, Smith P and MacDonald N 
(2012) Phosphorus management of beef cattle in northern Australia (reprinted 2015). Meat 
and Livestock Australia, Sydney. 

Jackson S, Finn M, Woodward E and Featherston P (2011) Indigenous socio-economic values and 
river flows. CSIRO Ecosystem Sciences, Darwin, NT. 

James C, VanDerWal J, Capon S, Hodgson L, Waltham N, Ward D, Anderson B and Pearson R (2013) 
Identifying climate refuges for freshwater biodiversity across Australia, National Climate 
Change Adaptation Research Facility, Gold Coast. 

Jardine TD, Bond NR, Burford MA, Kennard MJ, Ward DP, Bayliss P, Davies PM, Douglas MM, 
Hamilton SK, Melack JM, Naiman RJ, Pettit NE, Pusey BJ, Warfe DM and Bunn SE (2015) Does 
flood rhythm drive ecosystem responses in tropical riverscapes? Ecology 96(3), 684–692. Hyperlink to: Does flood rhythm drive ecosystem responses in tropical riverscapes?
. 

Joint Ore Reserves Committee (2004) Australasian code for reporting of exploration results, 
mineral resources and ore reserves. The JORC code (2004 edition). The Australasian Institute 
of Mining and Metallurgy, Australian Institute of Geoscientists and Minerals Council of 
Australia. Viewed 24 February 2024, Hyperlink to: Australasian code for reporting of exploration results, mineral resources and ore reserves 2004
. 

Joint Ore Reserves Committee (2012) Australasian code for reporting of exploration results, 
mineral resources and ore reserves. The JORC code (2012 edition). The Australasian Institute 
of Mining and Metallurgy, Australian Institute of Geoscientists and Minerals Council of 
Australia. Viewed 23 February 2024, Hyperlink to: Australasian code for reporting of exploration results, mineral resources and ore reserves 2012
. 

Junk W, Bayley P and Sparks R (1989) The flood pulse concept in river-floodplain systems. In: 
Dodge DP (ed.) Proceedings of the International Large River Symposium. Canadian Special 
Publication of Fisheries and Aquatic Sciences 106, 110–127. 

Keen (2003) Aboriginal economy and society: Australia at the threshold of colonisation. Oxford 
University Press, Melbourne. 

Kidd R (1997) The way we civilise: Aboriginal affairs – the untold story. University of Queensland 
Press, St Lucia. 

King AJ, Townsend SA, Douglas MM and Kennard MJ (2015) Implications of water extraction on 
the low-flow hydrology and ecology of tropical savannah rivers: an appraisal for northern 
Australia. Freshwater Science 34(2), 741–758. Hyperlink to: Implications of water extraction on the low-flow hydrology and ecology of tropical savannah rivers
. 

Kingsford R and Norman F (2002) Australian waterbirds – products of the continent's ecology. Emu 
102(1), 47–69. Hyperlink to: Australian waterbirds – products of the continent's ecology
. 


Kulendran N and Dwyer L (2010) Seasonal variation versus climate variation for Australian tourism. 
CRC for Sustainable Tourism, Australia. 

Lane R and Waitt G (2007) Inalienable places: self-drive tourists in Northwest Australia. Annals of 
Tourism Research 34(1), 105–121. Hyperlink to: Inalienable places: self-drive tourists in Northwest Australia
. 

Larson S and Herr A (2008) Sustainable tourism development in remote regions? Questions arising 
from research in the North Kimberley, Australia. Regional Environmental Change 8, 1–13. Hyperlink to: Sustainable tourism development in remote regions?
. 

Last P and Stevens J (2008) Sharks and rays of Australia. CSIRO, Collingwood. 

Lear KO, Gleiss AC, Whitty JM, Fazeldean T, Albert JR, Green N, Ebner BC, Thorburn DC, Beatty SJ 
and Morgan DL (2019) Recruitment of a critically endangered sawfish into a riverine nursery 
depends on natural flow regimes. Scientific Reports 9, 17071. Hyperlink to: Recruitment of a critically endangered sawfish into a riverine nursery depends on natural flow regimes
. 

Lei W, Masero JA, Piersma T, Zhu B, Yang H-Y and Zhang Z (2018) Alternative habitat: the 
importance of the Nanpu Saltpans for migratory waterbirds in the Chinese Yellow Sea. Bird 
Conservation International 28(4), 549–566. Hyperlink to: Alternative habitat: the importance of the Nanpu Saltpans for migratory waterbirds in the Chinese Yellow Sea
. 

Loneragan N, Bunn SE and Kellaway D (1997) Are mangroves and seagrasses sources of organic 
carbon for penaeid prawns in a tropical Australian estuary? A multiple stable-isotope study. 
Marine Biology 130(2), 289–300. Hyperlink to: Are mangroves and seagrasses sources of organic carbon for penaeid prawns in a tropical Australian estuary?
. 

Long JPM (1970) Aboriginal settlements: a survey of institutional communities in eastern Australia. 
Australian National University Press, Canberra. 

Lundberg C and Fredman P (2012) Success factors and constraints among nature-based tourism 
entrepreneurs. Current Issues in Tourism 15(7), 649–671. Hyperlink to: Success factors and constraints among nature-based tourism entrepreneurs
. 

Lyons P, and Barber, M (2018) Indigenous water values, rights, interests and development 
objectives in the Mitchell catchment. A technical report to the Australian Government from 
the CSIRO Northern Australia Water Resource Assessment, part of the National Water 
Infrastructure Development Fund: Water Resource Assessments. CSIRO, Australia. Hyperlink to: Indigenous water values, rights, interests and development objectives in the Mitchell catchment
. 

Lyons P, Barber M, Braedon P and Pert P (2024) Indigenous water values, rights, interests and 
development goals in the Southern Gulf Catchments: A literature review and implications for 
future research. A technical report from the CSIRO Southern Gulf Water Resource 
Assessment for the National Water Grid. CSIRO, Australia 

Marchant S and Higgins P (1990) Handbook of Australian, New Zealand and Antarctic Birds. 
Volume 1, Ratites to ducks. Oxford University Press, Melbourne. 

Martin RJ and Trigger D (2015) ‘Nothing never change’: mapping land, water and Aboriginal 
identity in the changing environments of northern Australia's Gulf Country. Settler Colonial 
Studies 5(4), 317–333. Hyperlink to: ‘Nothing never change’: mapping land, water and Aboriginal identity in the changing environments of northern Australia's Gulf Country
. 

Martin RJ (2012) Representing 'The Gulf': issues of place, race and identity in a region of Northern 
Australia. PhD thesis, University of Western Australia. 


McDavitt M (1996) The cultural and economic importance of sawfishes (family Pristidae). Shark 
News 8, 10–11. 

McGinness HM (2016) Waterbird responses to flooding, stressors and threats. A report prepared 
for the Murray–Darling Freshwater Research Centre as part of the Environmental Water 
Knowledge and Research Project. CSIRO, Canberra. 

McGrath A (1987) Born in the cattle: Aborigines in cattle country. Allen and Unwin, Sydney. 

McIntyre-Tamwoy S, Bird M and Atkinson F (2013) Aboriginal cultural heritage in the Flinders and 
Gilbert rivers: a desktop review. Report to the CSIRO by Archaeological and Heritage 
Management Solutions. Archaeological and Heritage Management Solutions, Sydney. 

McJannet D, Marvanek S, Kinsey-Henderson A, Petheram C and Wallace J (2014) Persistence of in-
stream waterholes in ephemeral rivers of tropical northern Australia and potential impacts 
of climate change. Marine and Freshwater Research 65(12), 1131–1144. Hyperlink to: Persistence of in-stream waterholes in ephemeral rivers of tropical northern Australia and potential impacts of climate change
. 

McJannet D, Yang A and Seo L (2023) Climate data characterisation for hydrological and 
agricultural scenario modelling across the Victoria, Roper and Southern Gulf catchments. A 
technical report from the CSIRO Victoria, Roper and Southern Gulf Water Resource 
Assessments for the National Water Grid. CSIRO, Australia. 

Meissner S (2021) The impact of metal mining on global water stress and regional carrying 
capacities – a GIS-based water impact assessment. Resources 2021,10, 120. Hyperlink to: The impact of metal mining on global water stress and regional carrying capacitie
. 

Memmott, P. and Channells, G. (2004). Southern Gulf of Carpentaria sea Country needs and issues 
Research. Hobart, National Oceans Office. 

Memmott P and Channells G (2004) Living on saltwater country: Southern Gulf of Carpentaria sea 
country management needs and issues. Paul Memmott and Associates in association with 
Aboriginal Environments Research Centre, University of Queensland, on behalf of the 
Carpentaria Land Council Aboriginal Corporation. 

Merlan F (1978) Making people quiet in the pastoral north: reminiscences of Elsey Station. 
Aboriginal History 2(1), 70–106. 

Merlan F (1981) Land, language and social identity in Aboriginal Australia. Mankind 13(2), 133–
148. Hyperlink to: Land, language and social identity in Aboriginal Australia
. 

Merlan F (1982) A Mangarrayi representational system: environmental and cultural symbolization 
in northern Australia. American Anthropologist 9, 145–166. 

Merlan F (1986) Mataranka land claim: senior anthropologist's report on behalf of the claimants. 
Northern Land Council, Darwin. 

Merrin L, Stratford D, Kenyon R, Pritchard J, Linke S, Ponce Reyes R, Blamey L, Buckworth R, 
Castellazzi P, Costin B, Deng R, Gannon R, Gao S, Gilbey S, Lachish S, McGinness H, Plagányi E 
and Waltham N (2024) Ecological assets of the Southern Gulf catchments to inform water 
resource assessments. A technical report from the CSIRO Southern Gulf catchments Water 
Resource Assessment for the National Water Grid. CSIRO, Australia. 


MITEZ (2021) North Queensland cotton gin assessment and feasibility study. Prepared for Mount 
Isa to Townsville Economic Development Zone Incorporated (MITEZ). Viewed 
13 December 2023, Hyperlink to: North Queensland cotton gin assessment and feasibility study
. 

Mitsch WJ, Bernal B and Hernandez ME (2015) Ecosystem services of wetlands. International 
Journal of Biodiversity Science, Ecosystem Services and Management, 11(1), 1–4. Hyperlink to: Ecosystem services of wetlands
. 

MMG (2023) Mineral resources and ore reserves statement as at June 30 2023. Viewed 
24 February 2024, Hyperlink to: Mineral resources and ore reserves statement as at June 30 2023
. 

MMG (2024) Dugald River. Viewed 24 February 2024, Hyperlink to: Dugald River
. 

Morgan D, Whitty J, Phillips N, Thorburn D, Chaplin J and McAuley R (2011) North-western 
Australia as a hotspot for endangered elasmobranchs with particular reference to sawfishes 
and the northern river shark. Journal of the Royal Society of Western Australia 94(2), 345–
358. 

Morgan DL, Ebner BC, Allen MG, Gleiss AC, Beatty SJ and Whitty JM (2017) Habitat use and site 
fidelity of neonate and juvenile green sawfish Pristis zijsron in a nursery area in Western 
Australia. Endangered Species Research 34, 235-249. Hyperlink to: Habitat use and site fidelity of neonate and juvenile green sawfish Pristis zijsron in a nursery area in Western Australia
. 

Morphy H (1991) Ancestral connections: art and an Aboriginal system of knowledge. University of 
Chicago Press, Chicago. 

Morphy H and Morphy F (1981) Yutpundji-Djindiwirritj (Roper Bar) Land Claim Book. Northern 
Land Council, Darwin. 

NAILSMA (2020) Business on Country diversification strategy – for enterprise, economic 
development and health and productive lands and seas. CRC for Developing Northern 
Australia. 

Nielsen DL, Cook RA, Ning N, Gawne B and Petrie R (2015) Carbon and nutrient subsidies to a 
lowland river following floodplain inundation. Marine and Freshwater Research 67(9), 1302–
1312. Hyperlink to: Carbon and nutrient subsidies to a lowland river following floodplain inundation
. 

Northey SA and Haque N (2013) Life cycle based water footprint of selected metal production – 
Assessing production processes of copper, gold and nickel. CSIRO, Australia. EP137374. 

NT Department of Environment, Parks and Water Security (2022) Land use mapping project of the 
Northern Territory (2016–2022) (LUMP). Open Data Portal, NT Government. Sourced 
28 March 2023, Hyperlink to: and use mapping project of the Northern Territory (2016–2022)
. 

NT Geological Survey (2024) Mineral Occurrence Database (MODAT). Version March 2023. 
Northern Territory Government. Viewed 10 January 2024, Hyperlink to: Mineral Occurrence Database
. 

NT Government (2020) Important wetlands. Northern Territory Government, Darwin. Viewed 08 
December 2023, https://nt.gov.au/environment/soil-land-vegetation/important-wetlands. 


NT Government (2024a) Uranium. Resourcing the Territory factsheet. Viewed 23 February 2024, Hyperlink to: Uranium. Resourcing the Territory factsheet
. 

NT Government (2024b) Strike tenure and geoscience information. NT Government. Viewed 
10 January 2024, Hyperlink to: Strike tenure and geoscience information
. 

Nye ER, Dickman CR and Kingsford RT (2007) A wild goose chase-temporal and spatial variation in 
the distribution of the Magpie Goose (Anseranas semipalmata) in Australia. Emu 107(1), 28–
37. Hyperlink to: A wild goose chase-temporal and spatial variation in the distribution of the Magpie Goose (Anseranas semipalmata) in Australia
. 

Ooi N and Laing JH (2010) Backpacker tourism: sustainable and purposeful? Investigating the 
overlap between backpacker tourism and volunteer tourism motivations. Journal of 
Sustainable Tourism 18(2), 191–206. Hyperlink to: Investigating the overlap between backpacker tourism and volunteer tourism motivations
. 

Outback Queensland Tourism Association (2021) Outback Queensland destination management 
plan 2021–2024. Viewed 10 March 2024, Hyperlink to: Outback Queensland destination management plan 2021–2024
. 

Peterson N (2013) On the persistence of sharing: personhood, asymmetrical reciprocity, and 
demand sharing in the Indigenous Australian domestic moral economy. The Australian 
Journal of Anthropology 24(2), 166–176. Hyperlink to: On the persistence of sharing: personhood, asymmetrical reciprocity, and demand sharing in the Indigenous Australian domestic moral economy
. 

Pettit NE, Bayliss P, Davies PM, Hamilton SK, Warfe DM, Bunn SE and Douglas MM (2011) Seasonal 
contrasts in carbon resources and ecological processes on a tropical floodplain. Freshwater 
Biology 56(6), 1047–1064. Hyperlink to: Seasonal contrasts in carbon resources and ecological processes on a tropical floodplain
. 

Pettit NE, Jardine TD, Hamilton SK, Sinnamon V, Valdez D, Davies PM, Douglas MM and Bunn SE 
(2012) Seasonal changes in water quality and macrophytes and the impact of cattle on 
tropical floodplain waterholes. Marine and Freshwater Research 63(9), 788–800. Hyperlink to: Seasonal changes in water quality and macrophytes and the impact of cattle on tropical floodplain waterholes
. 

Pettit NE, Naiman RJ, Warfe DM, Jardine TD, Douglas MM, Bunn SE and Davies PM (2017) 
Productivity and connectivity in tropical riverscapes of Northern Australia: ecological insights 
for management. Ecosystems 20(3), 492–514. Hyperlink to: Productivity and connectivity in tropical riverscapes of Northern Australia
. 

Peverell S (2005) Distribution of sawfishes (Pristidae) in the Queensland Gulf of Carpentaria, 
Australia, with notes on sawfish ecology. Environmental Biology of Fishes 73(4), 391–402. Hyperlink to: Distribution of sawfishes (Pristidae) in the Queensland Gulf of Carpentaria, Australia, with notes on sawfish ecology
. 

Phillips N, Chaplin JA, Peverell SC and Morgan DL (2017) Contrasting population structures of three 
Pristis sawfishes with different patterns of habitat use. Marine and Freshwater Research 
68(3). Hyperlink to: Contrasting population structures of three Pristis sawfishes with different patterns of habitat use
. 

Pickering CM and Hill W (2007) Impacts of recreation and tourism on plant biodiversity and 
vegetation in protected areas in Australia. Journal of Environmental Management 85, 791–
800. Hyperlink to: Impacts of recreation and tourism on plant biodiversity and vegetation in protected areas in Australia
. 

Pidgeon R and Humphrey C (1999) Some important ecological features of wetlands in the wet-dry 
tropics of northern Australia. In: Finlayson CM and Spiers AG (eds) A compendium of 
information for managing and monitoring wetlands in tropical Australia. Supervising Scientist 
Report 148. Supervising Scientist, Canberra, 40–62. 


Poff NL, Allan JD, Bain MB, Karr JR, Prestegaard KL, Richter BD, Sparks RE and Stromberg JC (1997) 
The natural flow regime: a paradigm for river conservation and restoration. BioScience 
47(11), 769–784. Hyperlink to: The natural flow regime: a paradigm for river conservation and restoration
. 

Poiani A (2006) Effects of floods on distribution and reproduction of aquatic birds. Advances in 
Ecological Research, Vol 39, 63–83. DOI: 10.1016/s0065-2504(06)39004-6. 

Poiner IR, Staples DJ and Kenyon R (1987) Seagrass communities of the Gulf of Carpentaria, 
Australia. Marine and Freshwater Research 38(1), 121–131. Hyperlink to: eagrass communities of the Gulf of Carpentaria, Australia
. 

Pollino C, Barber E, Buckworth R, Cadiegues M, Cook G, Deng A, Ebner B, Kenyon R, Liedloff A, 
Merrin L, Moeseneder C, Morgan D, Nielsen D, O'Sullivan, Ponce Reyes R, Robson B, 
Stratford D, Stewart-Koster B and Turschwell M (2018) Synthesis of knowledge to support 
the assessment of impacts of water resource development to ecological assets in northern 
Australia: asset analysis. A technical report to the Australian Government from the CSIRO 
Northern Australia Water Resource Assessment, part of the National Water Infrastructure 
Development Fund: Water Resource Assessments. CSIRO, Australia. Hyperlink to: Synthesis of knowledge to support the assessment of impacts of water resource development to ecological assets in northern Australia: asset analysis
. 

Prideaux B (2013) An investigation into factors that may affect the long term environmental and 
economic sustainability of tourism in northern Australia. The Cairns Institute, James Cook 
University, Cairns. 

Prosser I, Wolf L and Littleboy A (2011). Water in mining and industry. In: Prosser I (ed.) Water: 
science and solutions for Australia. CSIRO Publishing, Australia, 135–146. 

Pusey BJ, Jardine TD, Bunn SE and Douglas MM (2020) Sea catfishes (Ariidae) feeding on 
freshwater floodplains of northern Australia. Marine and Freshwater Research 71(12), 1628–
1639. DOI: 10.1071/MF20012. 

Pusey BJ, Kennard MJ and Arthington AH (2004) Freshwater fishes of north-eastern Australia. 
CSIRO Publishing, Collingwood. 

Queensland Department of Environment and Science (2022) WetlandSummary – facts and maps. 
WetlandInfo. Queensland Government. Viewed 23 April 2024, Hyperlink to: WetlandSummary – facts and maps
. 

Queensland Department of Environment and Science (2023a) Boodjamulla (Lawn Hill) National 
Park. Queensland Government. Viewed 17 February 2023, 
https://parks.des.qld.gov.au/parks/boodjamulla. 

Queensland Department of Environment and Science (2023b) Finucane Island National Park. 
Queensland Government. Viewed 08 December 2023, 
https://parks.des.qld.gov.au/parks/finucane-island. 

Queensland Department of Environment, Science and Innovation (2024a) Biodiversity status of 
2021 remnant regional ecosystems – Queensland, Queensland Government. Viewed 
16 September 2024, 
https://qldspatial.information.qld.gov.au/catalogue/custom/viewMetadataDetails.page?uuid=%7B8FDF54D2-654C-4822-8295-1D8E8E772373%7D. 


Queensland Department of Environment, Science and Innovation (2024b) Riversleigh World 
Heritage Area, Boodjamulla National Park (Aboriginal Land). Queensland Government. 
Viewed 10 March 2024, Hyperlink to: Riversleigh World Heritage Area, Boodjamulla National Park (Aboriginal Land
. 

Queensland Department of Regional Development, Manufacturing and Water (2021) North West 
Queensland. Queensland Government. Viewed 18 February 2024, Hyperlink to: North West Queensland
. 

Queensland Department of Regional Development, Manufacturing and Water (2023) Spatial 
dataset of the location and attributes for water licences and permits across Queensland. 
Department of Regional Development, Manufacturing and Water. State of Queensland 2021. 
https://qldspatial.information.qld.gov.au/catalogue/custom/viewMetadataDetails.page?uuid=%7B26BC4FC6-C8A1-4C5D-A79D-7EC0C1D2494F%7D. 

Queensland Department of Resources (2021) Mineral and coal exploration guideline. Viewed 
23 February 2024, Hyperlink to: Mineral and coal exploration guideline
. 

Queensland Government (2007) Water Plan (Gulf) 2007. Office of the Queensland Parliamentary 
Counsel, State of Queensland, Queensland, Australia. Viewed 11 Nov 2023, Hyperlink to: Water Plan (Gulf) 2007
. 

Queensland Government (2016) Water Regulation 2016. Office of the Queensland Parliamentary 
Counsel, State of Queensland, Queensland, Australia. Viewed 15 June 2024, Hyperlink to: Water Regulation 2016
. 

Queensland Government (2021a) Electricity supply options for the North West Minerals Province: 
consultation regulatory impact statement. Queensland Government, Brisbane. 

Queensland Government (2021b) Land use mapping – 1999 to 2019 – Queensland. Land use 
dataset downloaded 2 May 2023, 
https://www.qld.gov.au/environment/land/management/mapping/statewide- 
monitoring/qlump/qlump-datasets. 

Queensland Government Open Data Portal (2024a) Queensland borehole series. Viewed 
25 February 2024, Hyperlink to: Queensland borehole series
. 

Queensland Government Open Data Portal (2024b) Queensland mining and exploration tenure 
series. Viewed 10 January 2024, Hyperlink to: Queensland mining and exploration tenure series
. 

Queensland Parks and Wildlife Service (2022) Boodjamulla (Lawn Hill) National Park management 
plan 2022. Queensland Department of Environment and Science, Brisbane. 

Queensland Treasury (2023) About the Queensland economy. Queensland Government. Viewed 
15 July 2023, Hyperlink to: About the Queensland economy
. 

Raiber M, Taylor AR, Dupuy M, Priestley S, Crosbie RS, Knapton A, Hodgson G and Barry K (2024) 
Characterising groundwater resources of the Gilbert River Formation, Camooweal Dolostone 


and Thorntonia Limestone in the Southern Gulf catchments, Queensland and Northern 
Territory. A technical report from the CSIRO Southern Gulf Water Resource Assessment for 
the National Water Grid. CSIRO, Australia. 

Ramsar Convention Secretariat (2004) The Ramsar Convention manual: a guide to the convention 
on wetlands (Ramsar, Iran, 1971) (3rd ed.) Ramsar Convention Secretariat, Gland, 
Switzerland. 

Regional Development Australia (n.d.) Tourism industry. Viewed 10 March 2024, Hyperlink to: Publications
. 

Roberts, A. (2005). Frontier justice. A history of Gulf Country to 1900. Brisbane: University of 
Queensland Press. 

Roberts T. (2009) The brutal truth: what happened in the Gulf Country. The Monthly Nov. 2009, 
42–51. 

Rocha AR, Ramos JA, Paredes T and Masero JA (2017) Coastal saltpans as foraging grounds for 
migrating shorebirds: an experimentally drained fish pond in Portugal. Hydrobiologia 790(1), 
141–155. Hyperlink to: https://doi.org/10.1007/s10750-016-3025-y
. 

Rolfe J and Prayaga P (2007) Estimating values for recreational fishing at freshwater dams in 
Queensland. The Australian Journal of Agricultural and Resource Economics 51(2), 157–174. Hyperlink to: Estimating values for recreational fishing at freshwater dams in Queensland
. 

Rolfe JW, Larard AE, English BH, Hegarty ES, McGrath TB, Gobius NR, De Faveri J, Srhoj JR, Digby 
MJ and Musgrove RJ (2016) Rangeland profitability in the northern Gulf region of 
Queensland: understanding beef business complexity and the subsequent impact on land 
resource management and environmental outcomes. The Rangeland Journal 38, 261–272. Hyperlink to: Rangeland profitability in the northern Gulf region of Queensland
. 

Rose D, Bird (2004) Fresh water rights and biophilia: Indigenous Australian perspectives. Dialogue 
23(3), 35–43. 

Russell D and Garrett R (1983) Use by juvenile barramundi, Lates calcarifer (Bloch), and other 
fishes of temporary supralittoral habitats in a tropical estuary in northern Australia. Marine 
and freshwater research 34(5), 805–811. Hyperlink to: Use by juvenile barramundi, Lates calcarifer (Bloch), and other fishes of temporary supralittoral habitats in a tropical estuary in northern Australia
. 

SAMREC (2016) The South African code for the reporting of exploration results, mineral resources 
and mineral reserves (The SAMREC code). Academy of Science of South Africa, South Africa. 

Scambary B (2013) My country, mine country: Indigenous People, mining and development 
contestation in remote Australia. Centre for Aboriginal Economic Policy Research, Australian 
National University, Canberra. 

Schofield KA, Alexander LC, Ridley CE, Vanderhoof MK, Fritz KM, Autrey BC, DeMeester JE, Kepner 
WG, Lane CR, Leibowitz SG and Pollard AI (2018) Biota connect aquatic habitats throughout 
freshwater ecosystem mosaics. Journal of the American Water Resources Association 54(2), 
372–399. Hyperlink to: Biota connect aquatic habitats throughout freshwater ecosystem mosaics
. 

Short AD (2020) Australian coastal systems: beaches, barriers and sediment compartments. 
Springer Cham. Hyperlink to: Australian coastal systems: beaches, barriers and sediment compartments
. 


Short AD (2022) Australian beach systems: are they at risk to climate change? Ocean and Coastal 
Management 224, 106180. Hyperlink to: Australian beach systems: are they at risk to climate change?
. 

Sibanye Stillwater (2023) Mineral resources and mineral reserves report for the year ended 2022. 
Viewed 24 February 2024, Hyperlink to: Mineral resources and mineral reserves report for the year ended 2022
. 

Southern Gulf Natural Resource Management (2016) Southern Gulf Regional Natural Resource 
Management plan. Viewed 18 March 2024, 
https://www.southerngulf.com.au/resources/nrm-plan/. 

Speed R and Vanderbyl T (2024) Regulatory requirements for land and water development in the 
Northern Territory and Queensland. A technical report from the CSIRO Victoria and Southern 
Gulf Water Resource Assessments for the National Water Grid. CSIRO, Australia. 

Steven AH, Dylewski M and Curtotti R (2021) Australian fisheries and aquaculture statistics 2020. 
Fisheries Research and Development Corporation, Australian Bureau of Agricultural and 
Resource Economics and Sciences, Canberra. Hyperlink to: Australian fisheries and aquaculture statistics 2020
. 

Stevens J, McAuley R, Simpfendorfer C and Pillans R (2009) Spatial distribution and habitat 
utilisation of sawfish (Pristis spp) in relation to fishing in northern Australia. A report to 
Department of the Environment, Water, Heritage and the Arts, CSIRO. 

Stokes C, Jarvis D, Webster A, Watson I, Jalilov S, Oliver Y, Peake A, Peachey A, Yeates S, Bruce C, 
Philip S, Prestwidge D, Liedloff A, Poulton P, Price B and McFallan S (2023) Financial and 
socio-economic viability of irrigated agricultural development in the Roper catchment. A 
technical report from the CSIRO Roper River Water Resource Assessment for the National 
Water Grid. CSIRO, Australia. 

Strang V, (1997) Uncommon ground: cultural landscapes and environmental values. Berg, Oxford, 
New York. 

Strang V (2005) Common senses: water, sensory experience and the generation of meaning. 
Journal of Material Culture 10(1), 92–120. Hyperlink to: https://doi.org/10.1177/1359183505050096
. 

Summers J, Cavaye J and Woolcock G (2019) Enablers and barriers of tourism as a driver of 
economic and social-cultural growth in remote Queensland. Economic Papers 38(2), 77–94. Hyperlink to: Enablers and barriers of tourism as a driver of economic and social-cultural growth in remote Queensland
. 

Taçon PS,(2008) Rainbow colour and power among the Waanyi of Northwest Queensland. 
Cambridge Archaeological Journal 18(2), 163–176. Hyperlink to: Rainbow colour and power among the Waanyi of Northwest Queensland
. 

Tourism Research Australia (2019) Local government area profiles. Viewed 10 March 2024, Hyperlink to: Local government area profiles.
. 

Tourism Tropical North Queensland (2024) Savannah Way resilience toolkit – Reducing the 
impacts of seasonality on the Savannah Way: an operator guide. Tourism Tropical North 
Queensland website. Viewed 25 July 2024, Hyperlink to: Destination publications and brochures
. 

Toussaint S, Sullivan P and Yu S (2005) Water ways in Aboriginal Australia: an interconnected 
analysis. Anthropological Forum 15, 61–74. Hyperlink to: Water ways in Aboriginal Australia: an interconnected analysis
. 


Traill LW, Bradshaw CJA, Delean S and Brook BW (2010) Wetland conservation and sustainable use 
under global change: a tropical Australian case study using magpie geese. Ecography 33(5), 
818-825. Hyperlink to: Wetland conservation and sustainable use under global change: a tropical Australian case study using magpie geese
.

Traill LW, Bradshaw CJA, Field HE and Brook BW (2009) Climate change enhances the potential 
impact of infectious disease and harvest on tropical waterfowl. Biotropica 41(4), 414-423. Hyperlink to: Climate change enhances the potential impact of infectious disease and harvest on tropical waterfowl
. 

Trigger DS, (1987) Languages, linguistic groups and status relations at Doomadgee, an Aboriginal 
settlement in north-west Queensland, Australia. Oceania 57(3), 217–237. Hyperlink to: Languages, linguistic groups and status relations at Doomadgee, an Aboriginal settlement in north-west Queensland, Australia
. 

Trigger DS, (1992). Whitefella comin: Aboriginal responses to colonialism in northern Australia. 
Cambridge University Press, Cambridge. 

Trigger DS (1997) Land rights and the reproduction of Aboriginal culture in the Gulf country. Social 
Analysis: The International Journal of Anthropology, 41(3), 84–106. 

van Dam RA, Bartolo R and Bayliss P (2008) Chapter 2: Identification of ecological assets, pressures 
and threats. In: Bartolo R, Bayliss P and Van Dam RA (eds) Ecological risk assessment for 
Australia’s northern tropical rivers. Sub-project 2 of Australia’s Tropical Rivers – an 
integrated data assessment and analysis (DET18). A report to Land and Water Australia. 
Environmental Research Institute of the Supervising Scientist, National Centre for Tropical 
Wetland Research, Darwin NT, 14–161. 

Vance D, Bishop J, Dichmont C, Hall N, McInnes K and Taylor B (2003) Management of common 
banana prawn stocks of the Gulf of Carpentaria: separating the effects of fishing from those 
of the environment. CSIRO Report 1998/0716. CSIRO, Brisbane. 

Vance D, Haywood M, Heales D, Kenyon R and Loneragan N (1998) Seasonal and annual variation 
in abundance of postlarval and juvenile banana prawns Penaeus merguiensis and 
environmental variation in two estuaries in tropical northeastern Australia: a six year study. 
Marine Ecology Progress Series 163, 21–36. 

Vanderbyl T (2024) Technical report on the Northern Territory’s water planning arrangements. A 
technical report from the CSIRO Victoria River Water Resource Assessment for the National 
Water Grid. CSIRO, Australia. 

Vörösmarty CJ, McIntyre PB, Gessner MO, Dudgeon D, Prusevich A, Green P, Glidden S, Bunn SE, 
Sullivan CA, Liermann CR and Davies PM (2010) Global threats to human water security and 
river biodiversity. Nature 467(7315), 555–561. Hyperlink to: Global threats to human water security and river biodiversity
. 

Waanyi Native Title Aboriginal Corporation RNTBC (2020) Strategic Plan 2020–2025. Viewed 18 
March 2024, https://waanyipbc.org/strategic-plan. 

Waitt G, Lane R and Head L (2003) The boundaries of nature tourism. Annals of Tourism Research 
30(3), 523–545. Hyperlink to: The boundaries of nature tourism
. 

Waltham N, Burrows D, Butler B, Wallace J, Thomas C, James C and Brodie J (2013) Waterhole 
ecology in the Flinders and Gilbert catchments. A technical report to the Australian 
Government from the CSIRO Flinders and Gilbert Agricultural Resource Assessment, part of 
the North Queensland Irrigated Agriculture Strategy. 


Ward JV and Stanford J (1995) Ecological connectivity in alluvial river ecosystems and its disruption 
by flow regulation. Regulated rivers: research and management 11(1), 105-119. Hyperlink to: Ecological connectivity in alluvial river ecosystems and its disruption by flow regulation
. 

Warfe DM, Pettit NE, Davies PM, Pusey BJ, Hamilton SK, Kennard MJ, Townsend SA, Bayliss P, 
Ward DP, Douglas MM, Burford MA, Finn M, Bunn SE and Halliday IA (2011) The ‘wet-dry’ in 
the wet-dry tropics drives river ecosystem structure and processes in northern Australia. 
Freshwater Biology 56(11), 2169–2195. Hyperlink to: The ‘wet-dry’ in the wet-dry tropics drives river ecosystem structure and processes in northern Australia
. 

Waschka M and Macintosh A (2023) CSIRO Water Resource Assessments: Indigenous rights and 
interests in Queensland and the Northern Territory. A report from Barraband Consulting to 
the CSIRO to inform the CSIRO Roper River, Victoria Rivers and Southern Gulf Catchments 
Water Resource Assessments. CSIRO, Australia. 

Webster A, Jarvis D, Jalilov S, Philip S, Oliver Y, Watson I, Rhebergen T, Bruce C, Prestwidge D, 
McFallan S, Curnock M and Stokes C (2024a) Financial and socio-economic viability of 
irrigated agricultural development in the Southern Gulf catchments. A technical report from 
the CSIRO Southern Gulf Water Resource Assessment for the National Water Grid. CSIRO, 
Australia. 

Webster A, Jarvis D, Jalilov S, Philip S, Oliver Y, Watson I, Rhebergen T, Bruce C, Prestwidge D, 
McFallan S, Curnock M and Stokes C (2024b) Financial and socio-economic viability of 
irrigated agricultural development in the Victoria catchment, Northern Territory. A technical 
report from the CSIRO Victoria River Water Resource Assessment for the National Water 
Grid. CSIRO, Australia. 

Winter WH (1988) Supplementation of steers grazing Stylosanthes hamata pastures at Katherine, 
Northern Territory. Australian Journal of Experimental Agriculture 28, 669-682. 

Woodhams J, Larcombe J and George D (2011) Northern Prawn Fishery. In: Woodhams J, Stobutzki 
I, Vieira S, Curtotti R and Begg GA (eds) Fishery status reports 2010: status of fish stocks and 
fisheries managed by the Australian Government. Australian Bureau of Agricultural and 
Resource Economics and Sciences, Canberra, 69–89. 

Xiang H, Zhang Y and Richardson JS (2016) Importance of riparian zone: effects of resource 
availability at land-water interface. Riparian Ecology and Conservation, 2016(3), 1–17. Hyperlink to: Importance of riparian zone: effects of resource availability at land-water interface
. 




Part III Opportunities for 
water resource 
development 

Chapters 4 and 5 provide information on opportunities for agriculture and aquaculture in the 
catchment of the Southern Gulf rivers, that is Settlement Creek, Gregory–Nicholson River and 
Leichhardt River, the Morning Inlet catchments and the Wellesley island groups. This information 
covers: 

•opportunities for irrigated agriculture and aquaculture (Chapter 4)
•opportunities to extract and/or store water for use (Chapter 5).





Lake Moondarra on the Leichhardt River is a favoured 
recreational reserve for residents and tourists of Mount Isa. 
Photo: CSIRO – Nathan Dyer 



4 Opportunities for agriculture in the Southern Gulf 
catchments 
Authors: Yvette Oliver, Seonaid Philip, Tiemen Rhebergen, Ian Watson, Tony Webster, Peter Zund, 
Simon Irvin 

 
Chapter 4 presents information about the opportunities for irrigated agriculture and aquaculture 
in the catchment of the Southern Gulf rivers, that is Settlement Creek, Gregory–Nicholson River 
and Leichhardt River, the Morning Inlet catchments and the Wellesley island groups1, describing: 

1 Only those islands greater than 1000 ha are mapped 

• land suitability for a range of crop group × season × irrigation type combinations and for 
aquaculture, including key soil-related management considerations 
• cropping and other agricultural opportunities, including crop yields and water use 
• gross margins at the farm scale 
• prospects for integration of forages and crops into existing beef enterprises 
• aquaculture opportunities. 


The key components and concepts of Chapter 4 are shown in Figure 4-1. 

 

Figure 4-1 Schematic of agriculture and aquaculture enterprises as well as crop and/or forage integration with 
existing beef enterprises to be considered in the establishment of a greenfield irrigation development 

For more information on this figure please contact CSIRO on enquiries@csiro.au

4.1 Summary 

This chapter provides information on land suitability and the potential for agriculture and 
aquaculture in the Southern Gulf catchments. A mixture of field surveys and desktop analysis were 
used to generate the results presented in this chapter. For example, the land suitability results 
draw on extensive field visits (to describe, collect and analyse soils) and are integrated with state-
of-the-art digital soil mapping. Many of the results are expressed in terms of potential. The area of 
land suitable for cropping or aquaculture, for example, is estimated by considering the set of 
relevant soil and landscape biophysical attributes at each location and determining the most 
limiting attribute among them. It does not include water availability; cyclone or flood risk; 
legislative, regulatory or tenure considerations; or ecological, social or economic drivers that will 
inevitably constrain the actual area of land that is developed. Crops, forages and cropping systems 
results are based on data analysis and simulation models, and assume good agronomic practices 
producing optimum yields given the soil and climate attributes in the catchments. Likewise, 
aquaculture is assessed in terms of potential, using a combination of land suitability and the 
productive capacity of a range of aquaculture species. Information is presented in a manner to 
enable the comparison of a variety of agricultural and aquaculture options. 

The results from individual components (land suitability, agriculture, aquaculture) are integrated 
to provide a sense of what is potentially viable in the catchments. This includes providing specific 
information on a wide range of crop types for agronomy, water use and land suitability for 
different irrigation types; analyses of economic performance, such as crop gross margins (GMs); 
how more-intensive mixed cropping systems might be feasible with irrigation; and analyses of 
what is required for different aquaculture development options to be financially viable. 

4.1.1 Key findings 

Any agricultural resource assessment must consider two major factors: how much soil is suitable 
for a particular land use and where that soil is located. Based on a sample of 14 individual 
combinations of crop group × season of use × irrigation type, the amount of land classified as 
moderately suitable with considerable limitations or better ranges from 780,000 ha (Crop Group 7, 
wet-season furrow) to 4.7 million ha (Crop Group 14, perennial species, spray) before constraints 
such as water availability, environmental and other legislation and regulations, and a range of 
biophysical risks are considered (crop groups are defined in Section 4.2.3). The largest contiguous 
areas of soil suitable for broad-scale irrigation are the grey cracking clay soils of the lowland 
alluvial plains (Section 2.3.2, Figure 2-5), which are well located for small-scale irrigation 
developments based on water harvesting. Downstream of Doomadgee there are contiguous areas 
of red sandy and loamy soils suitable for irrigated vegetables and in the Leichhardt catchment 
downstream of Kajabbi there are opportunities for irrigated horticulture on the friable levee soils, 
and the adjacent friable clayey soils are suitable for broadacre irrigation. The clay soils on the 
Barkly Tableland in the south-west are suitable for broadacre cropping and overlie areas of 
intermediate- to regional-scale groundwater resources. 


Rainfed cropping 

Despite the theoretical possibility that rainfed crops could be produced using the considerable 
rainfall that arrives during the wet season, in practice significant agronomic and market-related 
challenges to rainfed crop production have prevented its expansion. Extensive areas of heavier 
clay soils (soil generic group (SGG) 9) across the Armraynald Plain and Barkly Tableland store 
enough plant available water (PAW) that could support potential high crop yields, particularly if 
cropped opportunistically in wetter years. However, frequent inundation and waterlogging of clay 
soils means that access for farming operations could be disrupted, increasing the risk to maximum 
yields through compromised timing of operations. Despite these challenges, higher-value crops 
such as pulses or cotton show potential, especially when grown in conjunction with irrigated 
farming. Loamy soils have low water-holding capacity and are hardsetting, which makes 
consistently achieving viable rainfed yields difficult. 

Irrigated cropping 

Irrigation reduces crop water stress and provides greater control over scheduling of crop 
operations to optimise production, including the option of growing through the cooler months of 
the dry season. 

Analyses of the performance of 19 potential irrigated cropping options in the Southern Gulf 
catchments indicate that achievable annual GMs could be up to about $4500/ha for broadacre 
crops, $8000/ha for annual row crop horticulture, $6000/ha for perennial fruit tree horticulture 
and $3000/ha for silviculture (plantation trees). While GMs are a key partial metric of farm 
performance, they should not be treated as fixed constants determined by the cropping system 
alone. They are a product of the farming and business management decisions, input costs and 
market opportunities. As such there are often niche opportunities to improve farm GMs and 
profitability, but these usually come at the expense of scalability. Farm financial metrics like GMs 
greatly amplify any fluctuations in commodity prices and input costs, so the mean GM does not 
accurately reflect the often substantial cashflow challenges in managing years of losses between 
those of windfall profits (particularly for horticulture). Crop yields and GMs presented in this 
chapter indicate what might be attained for each cropping option once it has achieved it’s 
sustainable agronomic potential. It is unrealistic to assume that these levels of performance would 
be achieved in the early years of newly established farms, and allowance should be made for an 
initial period of learning (see Chapter 6). 

Potential crop species that could be grown as a single crop per year were rated and ranked for 
their performance in the Southern Gulf catchments. Wet-season crops (planted January to early 
May) that are rated the most likely to be viable are cotton (Gossypium spp.), forages and peanuts 
(Arachis hypogaea). Dry-season crops (planted late March to August) that are rated the most likely 
to be viable are annual horticulture and cotton. Financial viability is determined both by crop 
options with the highest GMs and by associated capital and fixed costs, which are higher in more-
intensive farming like horticulture. The farm-scale measures of crop performance presented in this 
chapter are intended to be used in conjunction with the scheme-scale analyses of financial viability 
in Chapter 6 (as part of an integrated multi-scale approach). 

Sequential cropping systems involve planting more than one crop in the same year in the same 
field. These systems have the potential to significantly increase farm GMs. Annual broadacre and 


horticultural crops have been grown sequentially for many decades in tropical northern Australia. 
A wide range of sequential cropping options are potentially viable in the Southern Gulf 
catchments. Most suitable crop sequences include wet-season mungbean, grain sorghum or 
peanut with dry-season annual horticulture, wet season mungbean, peanut, soybean or grain 
sorghum with dry-season cotton, maize, chickpea or forage, and wet-season cotton with dry-
season mungbean, sorghum or forage. Scheduling back-to-back crops could be operationally tight 
in the Southern Gulf catchments, particularly on clay-rich soils with poor drainage, due to 
limitations on paddock accessibility. 

Crop selection is market driven in northern Australian regions like the Southern Gulf catchments. 
Rotations and crop sequences are therefore dynamic as growers develop an understanding of the 
benefits, trade-offs and management needs of different crop mixes and adapt to changing 
opportunities as commodity prices change. 

Integrating forages and hay into existing beef enterprises 

There are many theoretical benefits to growing irrigated forages and hay on-farm to enhance 
existing grazing enterprises. The use of on-farm irrigated forage and hay production would allow 
graziers greater options for marketing cattle: meeting market liveweight specifications for cattle at 
a younger age, meeting the specifications required for different markets than those typically 
targeted by cattle enterprises in the Southern Gulf catchments and providing cattle that meet 
market specification at a different time of the year. Forages and hay may also allow graziers to 
implement management strategies, such as early weaning or weaner feeding, which should lead 
to flow-on benefits throughout the herd, including increased reproductive rates. Some of these 
strategies are already practised within the Southern Gulf catchments but in almost all incidences 
are reliant on hay or other supplements purchased on the open market. By growing hay on-farm, 
the scale of these management interventions might be increased, at reduced net cost. 
Furthermore, the addition of irrigated feeds may allow graziers to increase the total number of 
cattle that can be sustainably carried on a property. 

Analysis of two irrigated hay or two irrigated forage stand-and-graze options compared to two 
base enterprises (with or without purchased hay, for weaners) suggested that irrigated forages or 
hay increased the total income and the amount of cattle liveweight sold. GMs were highest for the 
two irrigated hay options. The two stand-and-graze options returned the lowest GMs. A net 
present value (NPV) analysis suggested that a decision to irrigate would need to assume that beef 
prices remain high in comparison to the mean of the previous 10 years. Irrigation enterprises of 
the scale required involve high capital investment and additional or novel management skills. 

Aquaculture 

There are considerable opportunities for aquaculture development in northern Australia given the 
region’s natural advantages of a climate suited to farming valuable tropical species, large areas 
identified as suitable for aquaculture, and political stability and proximity to large global markets. 
The main challenges to developing and operating modern and sustainable aquaculture enterprises 
are regulatory barriers, global cost competitiveness and the remoteness of much of the suitable 
land area. The three species with the most aquaculture potential in the Southern Gulf catchments 
are black tiger prawns (Penaeus monodon), barramundi (Lates calcarifer) and red claw (Cherax 
quadricarinatus). 


Suitable land for lined ponds for freshwater species is widespread throughout the catchments due 
to the extensive distribution of favourable soil and land characteristics (flat land, non-rocky, deep 
soil). In contrast, options for freshwater species in earthen ponds are restricted to the 
impermeable alluvial clays to allow retention of water. The range for marine aquaculture is 
restricted to the tidal zones of the catchments and on the coastal plain within 2000 m of access to 
marine water. 

High annual operating costs (which can exceed the initial capital costs of development) mean that 
managing cashflow in the establishment years is challenging, especially for products that require 
multi-year grow-out periods. Input costs scale with increasing productivity, so improving 
production efficiency (such as feed conversion rate or labour-efficient operations) is much more 
important than increasing yields for aquaculture to be viable in the Southern Gulf catchments. It 
would be essential for any new aquaculture development to refine the production system and 
achieve the required levels of operational efficiency (input costs per kilogram of produce) using 
just a few ponds before scaling the enterprise to a larger number of ponds. 

4.1.2 Introduction 

Aspirations to expand agricultural development in the Southern Gulf catchments are not new, and 
across northern Australia there have been a number of initiatives to put in place large-scale 
agricultural developments since World War II (Ash, 2014; Ash and Watson, 2018). Ash and Watson 
(2018) assessed 11 such agricultural developments, four of which continue to operate at a 
regionally relevant scale, namely the Ord River Irrigation Area, the lower Burdekin, the Mareeba–
Dimbulah Water Supply Scheme and the Katherine mango industry. The Lakeland Downs 
development also continues, although it could not be categorised as regionally significant. Ash and 
Watson’s assessment included both irrigated and rainfed developments, and considered natural, 
human, physical, financial and social capitals. 

Key points to emerge from these analyses include the following: 

• The natural environment (climate, soils, pests and diseases) makes agriculture in northern 
Australia challenging, but these inherent environmental factors are not generally the primary 
reason for a lack of success. 
• The speed with which many of the developments were undertaken did not allow for a ‘learning 
by doing’ approach, leading at times to costly mistakes. 
• Physical capital, in the form of on-farm infrastructure, supply chain infrastructure and crop 
varieties, was a significant and ongoing impediment to success. For broadacre commodities that 
require processing facilities, these facilities need to be within a reasonable distance of 
production sites and at a scale to make them viable in the long term. 
• Financial plans tended to over estimate early production and returns on capital, and make overly 
optimistic expectations of the ability to scale up rapidly. This led to financial pressure on 
investors and a premature end to some developments. Furthermore, the need to have well-
connected and well-paying markets was often not fully appreciated. In more remote regions, 
higher-value products such as fruit, vegetables and niche crops proved more successful, 
although high supply chain costs to both domestic and export markets remain as impediments 
to expansion. 



• Most of the developments began in areas with no history of agricultural development, and there 
was no significant community of practitioners who could share experiences. 
• Management, planning and finances were the most important factors in determining the 
ongoing viability of agricultural developments. 


For developments to be successful, all factors relating to climate, soils, agronomy, pests, farm 
operations, management, planning, supply chains and markets need to be thought through in a 
comprehensive systems design. Particular attention needs to be paid to scaling up at a considered 
pace and being prepared for reasonable lags before achieving positive returns on investment. 

This chapter addresses the following questions for the Southern Gulf catchments: 

• How much land is suitable for cropping and in which suitability class? 
• Is irrigated cropping economically viable? 
• Which crop options perform best and how can they be implemented in viable mixed farming 
systems? 
• Can crops and forages be economically integrated with beef enterprises? 
• What aquaculture production systems might be possible? 


The chapter is structured as follows: 

• Section 4.2 describes how the land suitability classes are derived from the attributes provided in 
Chapter 2, with results given for a set of 14 combinations of individual crop group × season × 
irrigation type. Versatile agricultural land is described, and a qualitative evaluation of cropping is 
provided for a set of specific locations within the catchment. 
• Section 4.3 provides detailed information on crop and forage opportunities, including irrigated 
crop yields, water use and GMs. Agronomic principles, such as selection of sowing time, are 
provided, including a cropping calendar for scheduling farm operations. The information is 
synthesised in an analysis of the cropping systems that could best take advantage of 
opportunities in the Southern Gulf catchments environments while dealing with farming 
challenges. 
• Section 4.4 provides synopses for 11 crop and forage groups, including a focus on specific 
example species. 
• Section 4.5 discusses the candidate species and likely production systems for aquaculture 
enterprises, including the prospects for integrating aquaculture with agriculture. 



4.2 Land suitability assessment 

4.2.1 Introduction 

The term ‘suitability’ in the Assessment refers to the potential of the land for a specific land use, 
such as furrow-irrigated cotton. The term ‘capability’ (not used in the Assessment) refers to the 
potential of the land for broadly defined land uses, such as cropping or pastoral (DSITI and DNRM, 
2015). 

The overall suitability for a particular land use is determined by a number of environmental and 
soil attributes. These include, but are not limited to, climate at a given location, slope, drainage, 
permeability, available water capacity (AWC) of the soil, pH, soil depth, surface condition and 
texture. Examples of some of these attributes are provided in Section 2.3. From these attributes, a 
set of limitations to suitability are derived, which are then considered against each potential land 
use. 

4.2.2 Land suitability classes 

The overall suitability for a particular land use is calculated by considering the set of relevant 
attributes at each location and determining the most limiting attribute among them. This most 
limiting attribute then determines the overall land suitability classification. The classification is on 
a scale of 1 to 5 from ‘Suitable with negligible limitations’ (Class 1) to ‘Unsuitable with extreme 
limitations’ (Class 5), as shown in Table 4-1 (FAO, 1976, 1985). The companion technical report on 
digital soil mapping and land suitability (Thomas et al., 2024) provides a complete description of 
the land suitability assessment method, and the material presented in this section is taken from 
that report. Note that the land suitability maps and figures presented in this section do not 
consider flooding, risk of secondary salinisation or availability of water as discussed by Thomas et 
al. (2024). Consideration of these risks and others, along with further detailed soil physical, 
chemical and nutrient analyses, would be required to plan development at scheme, enterprise or 
property scale. Caution should therefore be employed when using these data and maps at fine 
scales. 

Table 4-1 Land suitability classes based on FAO (1976, 1985) as used in the Assessment 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au

4.2.3 Land suitability for crops, versatile agricultural land and evaluation of specific 
areas of interest 

The suitability framework used in this Assessment aggregates individual crops into a set of 21 crop 
groups (Table 4-2). The groups are based on the framework used by Andrews and Burgess (2021), 
with some additions considered prospective based on previous CSIRO work in northern Australia 
(e.g. Thomas et al., 2018), including in Queensland. From this set of crop groups, land suitability 
has been determined for 58 land use combinations of crop group × season × irrigation type 
(including rainfed) (Thomas et al., 2024). 

Table 4-2 Crop groups and individual land uses evaluated for irrigation (and rainfed) potential 

Crop groups and land uses are based on those used by Andrews and Burgess (2021), amended for the Southern Gulf 
catchments with the addition of crop groups 18 to 21 based on CSIRO’s previous work in northern Australia. Those 
used in the Northern Australia Water Resource Assessment (Thomas et al., 2018) are in boldface. 

MAJOR CROP GROUP 

CROP GROUP 

INDIVIDUAL CROPS ASSESSED 

Tree crops/horticulture 
(fruit) 

1 

Monsoonal tropical tree crops (0.5 m root zone) – mango, coconut, 
dragon fruit, Kakadu plum, bamboo, lychee 

 

2 

Tropical citrus – lime, lemon, mandarin, pomelo, lemonade, grapefruit 

Intensive horticulture 
(vegetables, row crops) 

3 

Cucurbits – watermelon, honeydew melon, rockmelon, pumpkin, 
cucumber, Asian melons, zucchini, squash 

 

4 

Fruiting vegetable crops – Solanaceae (capsicum, chilli, eggplant, 
tomato), okra, snake bean, drumstick tree 

 

5 

Leafy vegetables and herbs – kangkong, amaranth, Chinese cabbage, 
bok choy, pak choy, choy sum, basil, coriander, dill, mint, spearmint, 
chives, oregano, lemon grass, asparagus 

Root crops 

6 

Carrot, onion, sweet potato, shallots, ginger, turmeric, galangal, yam 
bean, taro, peanut, cassava 

Grain and fibre crops 

7 

Cotton, grains – sorghum (grain), maize, millet (forage) 

 

8 

Rice (lowland and upland) 

Small-seeded crops 

9 

Hemp, chia, quinoa, medicinal poppy 

Pulse crops (food 
legumes) 

10 

Mungbean, soybean, chickpea, navy bean, lentil, guar 

Industrial 

11 

Sugarcane 

Hay and forage (annual) 

12 

Annual grass hay/forages – sorghum (forage), maize (silage) 

 

13 

Legume hay/forages – blue pea, burgundy bean, cowpea, lablab, 
Cavalcade, forage soybean 

Hay and forage 
(perennial) 

14 

Perennial grass hay/forage – Rhodes grass, panics 

Silviculture/forestry 
(plantation) 

15 

Indian sandalwood 

 

16 

African mahogany, Eucalyptus spp., Acacia spp. 

 

17 

Teak 

Intensive horticulture 
(vegetables, row crops) 

18 

Sweet corn 




MAJOR CROP GROUP 

CROP GROUP 

INDIVIDUAL CROPS ASSESSED 

Oilseeds 

19 

Sunflower, sesame 

Tree crops/horticulture 

20 

Banana, coffee 

 

21 

Cashew, macadamia, papaya 



 
A sample of 14 of these individual land use combinations – that covers a mixture of crops, 
irrigation types and seasons, grown or trialled in northern Australia – is shown in Figure 4-2. 
Depending on land use, the amount of land classified as Class 3 or better for these sample land 
uses ranges from about 360,000 ha (Crop Group 10, wet-season rainfed) to 5.1 million ha (Crop 
Group 14 under spray irrigation). Much of this land is rated as Class 3, and so has considerable 
limitations, although nearly 1.7 million ha of Class 2 land is available for Crop Group 14 crops 
under spray irrigation and between about 340,000 ha and about 970,000 ha of Class 2 land for the 
other crop groups under spray or trickle irrigation. Ranges of suitability geographic distributions 
are shown on maps in the crop synopses in Section 4.4. 

 

Figure 4-2 Area (ha) of the Southern Gulf catchments mapped in each of the land suitability classes for 14 selected 
land use combinations (crop group × season × irrigation type) 

The five land suitability classes are described in Table 4-1 and more detail on the crop groups is given in Table 4-2. 

Land suitability classes mapped for southern gulf
For more information on this figure please contact CSIRO on enquiries@csiro.au

In order to provide an aggregated summary of the land suitability products, an index of 
agricultural versatility was derived for the Southern Gulf catchments (Figure 4-3). Versatile 
agricultural land was calculated by identifying where the highest number of the 14 selected land 
use options presented in Figure 4-2 were mapped as being suitable (i.e. suitability classes 1 to 3). 

Qualitative observations on each of the areas mapped as ‘A’ to ‘F’ in Figure 4-3 are provided in 
Table 4-3. 


Figure 4-3 Agricultural versatility index map for the Southern Gulf catchments 

High index values denote land that is likely to be suitable for more of the 14 selected land use options. The map shows 
specific areas of interest (A to F) from a land suitability perspective, which are discussed in Table 4-3. Note that the 
versality index mapped here does not consider flooding, risk of secondary salinisation or availability of water. 

Versatile agricultural land map
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Table 4-3 Qualitative land evaluation observations in Southern Gulf catchments areas A to F shown in Figure 4-3 

Further information on each soil generic group (SGG) and a map showing spatial distribution can be found in Section 
2.3. 

 AREA 

SOIL AND LOCATION 

SOIL DESCRIPTION, POTENTIAL LAND USES AND LIMITATIONS 

 A 

Cracking clay soils (SGG 9) of the 
Armraynald Plain formed from the 
Pleistocene Armraynald Beds and 
broad alluvial plains of the major 
rivers, particularly the Gregory and 
lower Leichhardt rivers 

Comprises rarely flooded plains between the Gregory and Leichhardt rivers and 
regularly flooded plains on Lawn Hill Creek and between Gregory River and 
Running Creek. Soils are mainly moderately well-drained to imperfectly drained 
grey, brown or black cracking clay soils (SGG 9) with self-mulching to hard-
setting structured surfaces. The imperfectly drained grey clay soils occur on the 
northern part of the Armraynald Plain and along Lawn Hill Creek. The brown 
cracking clays that occur on the south-eastern part of the plain east of the 
Leichhardt River can also be imperfectly drained. The soils may be suitable for 
furrow- or spray-irrigated vegetables (except root crops), rice, sugarcane and 
dry-season grain, forage, pulse crops, sweet corn and cotton. The main 
limitations are workability and potential wet-season flooding. Management of 
wet-season cropping needs to consider crop tolerance to seasonal wetness and 
flood duration, depth and frequency. How soil salinity will accumulate over 
time in these soils is currently unknown but must be monitored, especially in 
the imperfectly drained soils. 

 B 

Friable non-cracking clays or sandy 
clay loams (SGG 2) and loam over 
relatively friable red clay subsoils 
(SGG 1.1) formed on alluvium along 
the middle reaches of the 
Leichhardt River 

The friable non-cracking clays (SGG 2) are moderately well to well-drained, 
brown, red or grey, structured sandy clay loam or silty clay soils. The loam over 
red clay subsoils (SGG 1.1) are well drained with moderately thick (<0.2 m), 
loamy surface soils over red, structured clay subsoils developed on alluvium 
adjacent to the Leichhardt River. Soils are suitable for a range of spray- or 
trickle-irrigated vegetables, sugarcane, oilseed, sweet corn and wet-season and 
dry-season grain, forage, pulse crops and cotton. Wet-season tree crops are 
also likely to be suitable. Extents of suitable lands are generally minor, resulting 
in small and/or narrow areas limiting paddock size and irrigation infrastructure 
layout. The main limitation is flooding post-cyclone. Soil erosion during flood 
events and compaction from tillage are land degradation risks. 

 C 

Red loamy soils (SGG 4.1) and red 
sandy soils (SGG 6.1) occurring near 
Doomadgee on elevated narrow 
alluvial plains along the Nicholson 
River 

The red loamy soils (SGG 4.1) occur downstream of Doomadgee on the 
southern side of the Nicholson River on a Pleistocene elevated floodplain. Soils 
are well-drained brown, silty loam moderately thick (<0.2 m) surface soils over 
red silty clay subsoils. Soils may be suitable for irrigated agriculture although 
the narrow tracts along the Nicholson River may limit infrastructure layout. 
Compaction from tillage is a land degradation risk. 

On the northern side of the Nicholson River, red sandy soils (SGG 6.1) have 
developed on an elevated alluvial plain near Doomadgee. Soils are well-drained 
red sand to sandy loams and have limited very low to low soil AWC, hence are 
only suited to irrigated horticulture using trickle or drip systems. There is a risk 
of deep drainage and nutrification of the adjacent river and groundwater table. 

 D 

Grey cracking clays (SGG 9) from 
Cenozoic sediments on the Barkly 
Tableland 

Soils are self-mulching, grey or occasionally brown, cracking clays (SGG 9), 
moderately deep (>1.0 m) to very deep (>1.5 m) and moderately well drained. 
Localised rockiness/stoniness in the soil profile may affect farming. Surfaces 
are gilgaied, and soils are formed of structured clay with calcareous nodules 
and gypsum crystals. Soils are suitable for trickle-irrigated mangoes and 
vegetables as well as wet-season cotton, grain and forage crops. Soil 
workability and rockiness are the main limitations, and deep gilgai microrelief 
may restrict land-levelling operations in some areas. There is a risk of water 
erosion on bare paddocks late in the dry season due to early rains. 

 E 

Sandy soils (SGG 6.2) formed in 
sandy sediments on old lateritic 
surfaces of the Doomadgee Plains 

Soils are brown, yellow or grey and sandy (SGG 6.2), highly permeable, well-
drained, deep to very deep (1–1.5 m), commonly encountering ferricrete rock 
within 1 m. There is potential for irrigated horticulture using trickle or drip 
systems. In the absence of irrigation, agricultural potential of these soils is low. 
Soil depth and water-holding capacity are the main limitations. 

 F 

Deep sandy soils (SGG 6) formed on 
an elevated sand plain in the 
Buddycurrawa Creek subcatchment 
of the Gulf Fall physiographic unit 

Sandy soils are brown or red (SGG 6), highly permeable, moderately well to 
well-drained, and deep to very deep (>1.2 m). At depth these soils may be 
mottled and with no coarse fragments or nodules. The soil has a low AWC 
(<60 mm). There is potential for irrigated horticulture using trickle or drip 
systems. Agricultural potential of these soils is low without irrigation. 




Land suitability and its implications for crop management are discussed in more detail for a 
selection of crops in Section 4.4, where land use suitability of a given crop and irrigation 
combination are mapped, along with information critical to the consideration of the crop in an 
irrigated farm enterprise. Land suitability maps for all 58 land use combinations are presented in 
the companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). 

4.3 Crop and forage opportunities in the Southern Gulf catchments 

4.3.1 Introduction 

This section presents results on the farm ‘performance’ of individual crop options, where 
performance is quantified specifically as crop yields, the amount of applied irrigation water 
(accounting for application efficiency) and GMs. Performance is presented with information on 
agronomic principles and farming practices to help interpret the viability of new (greenfield) 
farming opportunities in the Southern Gulf catchments. The individual crop options are grouped 
into rainfed broadacre, irrigated broadacre, irrigated horticulture and plantation tree crops 
(sections 4.3.3 to 4.3.7), and viability is discussed in a section on cropping systems (Section 4.3.8). 
That section considers the mix of farming opportunities and practices, for both single and 
sequential cropping systems, with the greatest potential to be profitably and sustainably 
integrated within the Southern Gulf catchments environments. Finally, Section 4.3.9 evaluates the 
viability of integrating irrigated forages into existing beef production. These farm-scale analyses 
are intended to be used in conjunction with the scheme-scale analyses of viability in Chapter 6 (as 
part of an integrated multi-scale analysis). 

Nineteen irrigated crop options were selected to evaluate their potential performance in the 
Southern Gulf catchments (Table 4-4). The crops were selected to be compatible with the land 
suitability crop groups (Table 4-2), provided that: (i) they had the potential to be viable in the 
Southern Gulf catchments (based on knowledge of how well these crops grow in other parts of 
Australia), (ii) they were of commercial interest for possible development in the region and (iii) 
there was sufficient information on their agronomy, and farming costs and prices, for quantitative 
analysis. The analyses used a combination of Agricultural Production Systems sIMulator (APSIM) 
crop modelling and climate-informed extrapolation to estimate potential yield and water use for 
each crop. Those values were then used in a farm GM tool specifically designed for greenfield 
farming developments (like those in the Southern Gulf catchments, where there are very few 
existing commercial farms or farm financial models). In particular, extrapolations used close 
similarities in climate and soils between possible cropping locations in the Southern Gulf 
catchments and established irrigated cropping regions at similar latitudes near the Ord River 
Irrigation Area (WA) and the Mareeba–Dimbulah Irrigation Area (Queensland) (Figure 4-4). Full 
details of the approach are described in the companion technical report on agricultural viability 
and socio-economics (Webster et al., 2024). Section 4.4 provides further details on opportunities 
and constraints in the Southern Gulf catchments, for example, crops in each of the agronomic crop 
types listed in Table 4-4. 

 


Table 4-4 Crop options for which performance was evaluated in terms of water use, yields and gross margins 

The methods used for estimating crop yield and irrigation water requirements are coded as: A = APSIM; E = climate-
informed extrapolation. ‘A, E’ indicates that A is the primary method and E is used for sensibility testing. ‘E, A’ 
indicates that E is the primary method and A is used for applying adjustments. ‘Mango (KP)’ is Kensington Pride and 
‘Mango (PVR)’ is an indicative new high-yielding variety likely to have plant variety rights (e.g. Calypso). Note that 
crops that are agronomically similar in terms of the commodities they produce (as categorised in the table) may differ 
in how they respond to soil constraints. The crop type categories in the table are therefore necessarily different to the 
crop groups used in the land suitability section (which are grouped according to shared soil requirements and 
constraints; Table 4-2). 

CROP TYPE 

CROP 

IRRIGATION WATER 
ESTIMATE METHOD 

YIELD ESTIMATE 
METHOD 

Broadacre 

 

 

 

Cereal 

Sorghum (grain) 

A, E 

A, E 

 

Maize 

A, E 

A, E 

Pulse 

Mungbean 

A, E 

A, E 

 

Chickpea 

A, E 

A, E 

 

Soybean 

A, E 

A, E 

Oilseed 

Sesame 

E 

E 

 

Peanut 

A, E 

A, E 

Industrial 

Cotton (dry season) 

A, E 

A, E 

 

Cotton (wet season) 

A, E 

A, E 

 

Hemp 

E 

E 

Forage 

Rhodes grass 

A, E 

A, E 

Horticulture (row) 

Rockmelon 

E 

E 

 

Watermelon 

E 

E 

 

Onion 

E 

E 

 

Capsicum 

E 

E 

Horticulture (tree) 

Mango (PVR) 

E 

E 

 

Mango (KP) 

E 

E 

 

Lime 

E 

E 

Plantation tree 

African mahogany 

E 

E 



 


(a) Mean monthly rainfall 

(b) Mean daily maximum temperature 

 

 

(c) Mean daily solar radiation 

(d) Mean daily minimum temperature 

 

 

 



Monthly daily solar radiation comparisons
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Monthly min temp comparisons
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A graph of the month of the year
Description automatically generated
Figure 4-4 Climate comparisons of Southern Gulf catchments’ sites with established irrigation areas at Kununurra 
(WA) and Mareeba (Queensland) 

Southern Gulf catchments sites are Westmoreland, Gregory, Kamilaroi and Gallipoli. 

Four locations were selected for the APSIM simulations to represent some of the best potential 
farming conditions across the varied environments in the Southern Gulf catchments: 

• A Vertosol with a Gregory (–18.65°S, 139.25°E) climate. This soil represents the farming 
conditions of the lowland cracking clays (SGG 9; marked ‘A’ in Figure 4-3) and are the most 
extensive arable areas in the Southern Gulf catchments. During the wet-season, access and 
limitations from floodplain inundation and workability may constrain cropping. Using grain 
sorghum as an indicator crop, the plant available water capacity (PAWC) of the modelled soil 
was 212 mm (noting that PAWC differs between crops with different rooting patterns and 
physiologies). Daily historical meteorological data used for these simulations was from the 
Gregory weather station, which has a mean annual rainfall of about 540 mm. 
• A Chromosol with a Kamilaroi (–19.36°S, 140.04°E) climate. This soil represents some of the 
better farming conditions among the friable non-cracking clay soils (SGG 1 and Dermosols, SGG 
2; marked ‘B’ in Figure 4-3) along the middle reaches of the Leichhardt River. The PAWC of this 
soil for grain sorghum was 93 mm, and the mean annual rainfall for Kamilaroi is about 577 mm. 


Monthly rainfall comparisons
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Monthly max temperature comparisons
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• A red Kandosol with a Westmoreland (–17.34°S, 138.25°E) climate. This soil represents some of 
the better farming conditions among the loamy soils (SGG 4; marked ‘C’ in 
• A Vertosol with a Gallipoli (–19.14°S, 137.87°E) climate. This soil represents some of the better 
farming conditions among the cracking clay soils (SGG 9; marked ‘D’ in Figure 4-3), having less 
wet-season issues than the Gregory (lowland) cracking clay soils, although surface and profile 
rock may limit some areas. The PAWC of this soil for grain sorghum was 146 mm, and the mean 
annual rainfall for Gallipoli is about 420 mm. 


To assist with interpreting the later results, some information is first provided on agronomic 
principles related to the scheduling of critical farm operations such as sowing and irrigation in 
relation to Southern Gulf catchments environments. 

4.3.2 Cropping calendar and time of sowing 

Time of sowing can have a significant effect on achieving economical crop and forage yields, and 
on the availability and amount of water for irrigation required to meet crop demand. Cropping 
calendars identify optimum sowing times of different crops and are essential tools for scheduling 
farm operations (Figure 4-5) so that crops can be reliably and profitably grown. No cropping 
calendar existed for the Southern Gulf catchments before the Assessment. 

Sowing windows vary in both timing and length among crops and regions, and they consider the 
likely suitability and constraints of weather conditions (e.g. heat and cold stress, radiation, and 
conditions for flowering, pollination and fruit development) during each subsequent growth stage 
of the crop. Limited field experience currently exists in the Southern Gulf catchments for most of 
the crops and forages evaluated. This cropping calendar (Figure 4-5) is therefore based on 
knowledge of crops derived from past and current agricultural experience in the Ord River 
Irrigation Area (WA), Katherine and Douglas–Daly regions (NT), Mareeba–Dimbulah Water Supply 
Scheme and the Burdekin region (Queensland). 

Some annual crops have both wet-season and dry-season cropping options. Perennial crops are 
grown throughout the year, so growing seasons and planting windows are less well defined. 
Generally, perennial tree crops are transplanted as small plants, and in northern Australia this is 
usually timed towards the beginning of the wet season to take advantage of wet-season rainfall. 
The cropping calendar presented here considers the optimal climate conditions for crop growth 
and considers operational constraints specific to the local area. Such constraints include wet-
season difficulties in access and trafficability, and limitations on the number of hectares that 
available farm equipment can sow/plant. For example, clay-rich alluvial Vertosols, such as those 
found across the Armraynald and Cloncurry plains and Barkly Tableland, are likely to present 
severe trafficability constraints through much of the wet season in the Southern Gulf catchments, 
while sandier Kandosols would present far fewer trafficability restrictions in scheduling farming 
operations (Figure 4-6). 

 




Figure 4-5 Annual cropping calendar for irrigated agricultural options in the Southern Gulf catchments 

WS = wet season; DS = dry season. 

Many suitable annual crops can be grown at any time of the year with irrigation in the Southern 
Gulf catchments. Optimising crop yield alone is not the only consideration. Ultimately, sowing date 
selection must balance the need for the best growing environment (optimising solar radiation and 
temperature) with water availability, pest avoidance, trafficability during the growing season and 
at harvest, crop rotation, supply chain requirements, infrastructure development costs, market 
access considerations and potential commodity price. Many summer crops from temperate 
regions are suited to the tropical dry season (winter) because temperatures are closer to their 

Crop planting times
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CROP TYPECROPDECJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVCROP DURATION(days)
Cereal cropsSorghum (WS)ssssssgggg110—140Sorghum (DS)gssssssssssggg110—140Maize (WS)ssssssggg110—140Maize (DS)gssssssssssggg110—140Rice (WS)ssssgggg120—160+
Rice (DS)ssssgggg90—135 
Pulse crops (food legumes)Mungbean (WS)ssssggg70—85Mungbean (DS)ssssggg70—85Chickpeassssgggg100—120OilseedsSoybean (WS)ssssssgggg110—130Sesamessssssggg110—130Root cropsPeanut (WS)ssssssggggg100—140Peanut (DS)gssssggg100—140Cassavassssssssssssssggggg180—210Industrial cropsCotton (WS)ssssssgggg100—120Cotton (DS)ssssssggggg100—120Hemp (fibre)ssssssssgggg110—150Forage, hay, silageRhodes grassggspspspgggspspspspPerennial (regrows)
Forage sorghumssssssssgggssssssgg60—80 (regrows)
Forage milletssssssssgggssssssgg60—80 (regrows)
Forage maizegssssssgggssssssgg75—90Forage legumesCavalcadessggggggssss150—180Lablabssssssssssggggg130—160Horticulture (row crops)Melonsssssssgggg70—110Oniongssssssssssgggg130—160Capsicum, chilli, tomatossssggggg70—90 from transplantPineapplespspspgggggggPerennialHorticulture (vine)Table grapesspspspgggggggggPerenialHorticulture (tree crops)MangospspspgggggggggPerennialAvocadospspspgggggggggPerennialBananaspspspspggggggggPerennialLimespspspgggggggggPerennialLemonspspspgggggggggPerennialOrangespspspgggggggggPerennialCashewspspspgggggggggPerennialMacadamiaspspspgggggggggPerennialPlantation trees (silviculture)Africian mahoganyspspspgggggggggPerennialIndian sandalwoodspspspgggggggggPerennial

optima and/or there is more consistent solar radiation (e.g. maize (Zea mays), chickpea (Cicer 
arietinum) and rice (Oryza sativa)). For sequential cropping systems (which grow more than a 
single crop in a year in the same field), growing at least one crop partially outside its optimal 
growing season can be justified if this increases total farm profit per year and there are no adverse 
biophysical consequences (e.g. pest build-up). 

(a) 

 

(b) 

 



Percent of years soil wetness is less than trafficability threshold for soils
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\5_Agriculture_economics\4_S_Gulf\4_Data\4_APSIMmodelling\SOGWRA-Charts_APSIM_v3.xlsx
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Figure 4-6 Soil wetness indices that indicate when seasonal trafficability constraints are likely to occur on sands, 
Kandosols (loamy sands) and Vertosols (high clay) with a Gregory climate for two thresholds (a) 80% and (b) 70% of 
the maximum plant available water capacity 

The indices show the proportion of years (for dates at bi-monthly intervals) when plant available water (PAW) in the 
top 30 cm of the soil is below two threshold proportions (70% and 80%) of the maximum plant available water 
capacity value. Lower values indicate there would be fewer days at that time of year when fields would be accessible 
and trafficable. Estimates are from 100-year Agricultural Production Systems Simulator simulations without a crop. In 
actual farming situations, once a crop canopy is established later in the season, crop water extraction from the soil 
would assist in alleviating these constraints. 

Growers also manage time of sowing to optimally use stored soil water and in-season rainfall, and 
to avoid rain damage at maturity. In the Southern Gulf catchments mean monthly rainfall is highly 
variable between the wet and dry seasons (Figure 4-4) and irrigation allows growers the flexibility 
in sowing date and in the choice and timing of crop or forage systems in response to seasonal 
climate conditions. Depending on the rooting depth of a particular species and the length of 
growing season, crops established at the end of the wet season may access a full profile of soil 
water (e.g. ≥200 mm PAWC for some Vertosols). While timing sowing to the end of the wet season 
to take advantage of soil water may reduce the overall irrigation requirement, it may expose crops 
to periods of unfavourable solar radiation or temperatures during plant development and 
flowering. It may also prevent the implementation of a sequential cropping system. 

4.3.3 Rainfed cropping 

Rainfed cropping (crops grown without irrigation, relying only on rain) has been practised by 
farmers in the NT and Queensland for almost 100 years, yet only small areas of rainfed crop 
production currently occur each year in the very remote northern regions. This indicates that, 
despite the theoretical possibility of producing rainfed crops using the significant wet-season 

Percent of years soil wetness is less than trafficability threshold for soils
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rainfall in the Southern Gulf catchments, in practice significant agronomic and market-related 
challenges to rainfed crop production have prevented its expansion to date. 

Without the certainty provided by irrigation, rainfed cropping is opportunistic in nature, relying on 
favourable conditions in which to establish, grow and harvest a crop. The annual cropping 
calendar in Figure 4-5 shows that, for many crops, the sowing window includes the month of 
February. For relatively short-season crops, such as forage sorghum and mungbean (Vigna 
radiata), this coincides with both the sowing time that provides close to maximum crop yield and 
the time at which the season’s water supply can be accessed with a high degree of confidence. 
Table 4-5 shows how plant available soil water content at sowing and subsequent rainfall in the 90 
days after each sowing date varies over three different sowing dates for a Vertosol in the Southern 
Gulf catchments at Gregory. As sowing is delayed from February to April, the amount of stored soil 
water decreases. However, there is a significant decrease in rainfall in the 3 months after sowing. 
Combining the median PAW in the soil profile at sowing, and the median rainfall received in the 90 
days following sowing, provides totals of 392, 250 and 183 mm for the February, March and April 
sowing dates, respectively. For drier-than-average years (80% probability of exceedance), the soil 
water stored at sowing and the expected rainfall in the ensuing 90 days (<260 mm) would result in 
water stress and comparatively reduced crop yields. In wetter-than-average years (20% probability 
of exceedance) the amount of soil water at the end of February combined with the rainfall in the 
following 90 days (527 mm) is sufficient to grow a good short-season crop (noting that the timing 
of rainfall is also important because some rain is ‘lost’ to runoff, evaporation and deep drainage 
between rainfall events). Opportunistic rainfed cropping would target those wetter years where 
PAW at the time of sowing indicated a higher chance of harvesting a profitable crop. 

Table 4-5 Soil water content at sowing, and rainfall for the 90-day period following sowing for three sowing dates, 
based on a Gregory climate on a Vertosol 

The 80%, 50% (median) and 20% probabilities of exceedance values are reported for the 100 years between 1920 and 
2020. The lower-bound values (80% exceedance) occur in most years, while the upper-bound values only occur in the 
most exceptional upper 20% of years. PAW = plant available water stored in soil profile. 

SOWING DATE 

PAW 
AT SOWING DATE 
(mm) 

RAINFALL IN 90 DAYS 
FOLLOWING SOWING DATE 
(mm) 

TOTAL STORED SOIL WATER + 
RAINFALL IN SUBSEQUENT 90 DAYS 
(mm) 



80% 

50% 

20% 

80% 

50% 

20% 

80% 

50% 

20% 

1 February 

111 

176 

220 

132 

200 

308 

260 

392 

527 

1 March 

133 

178 

208 

24 

78 

180 

171 

250 

369 

1 April 

120 

173 

193 

0 

6 

58 

136 

183 

240 



Figure 4-7 highlights the impact on rainfed crop yields of the diminishing water availability from 
early to late wet-season planting. This constraint is much more severe for sandier soils that have 
less capacity to store PAW (like Kandosols on the Doomadgee Plain in the Southern Gulf 
catchments, Figure 4-7a), than finer textured soils (like the alluvial Vertosols in the Southern Gulf 
catchments, Figure 4-7b). However, the frequent inundation and waterlogging of clay soils, which 
are often located adjacent to rivers, means that crops cannot always be sown at optimum times; 
fertiliser can be lost due to runoff, drainage and denitrification; and in-crop management (e.g. for 
weed, disease and insect control) cannot be undertaken cost-effectively with ground-based 
equipment in a timely manner, a critical requirement for rainfed crop production to succeed. 


Those disruptions decrease the chance that high potential yields in the top 20% of the seasons 
could be achieved in practice. 

(a) Gregory Kandosol (sandy, PAWC 129 mm) 

 

(b) Gregory Vertosol (high clay, PAWC 212 mm) 

 



Influence of planting date on yield - vertosol
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\5_Agriculture_economics\4_S_Gulf\4_Data\4_APSIMmodelling\SOGWRA-Charts_APSIM_v3.xlsx
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Figure 4-7 Influence of planting date on rainfed grain sorghum yield at Gregory for a (a) Kandosol and (b) Vertosol 

Estimates are from Agricultural Production Systems Simulator simulations with planting dates on the 1st and 15th of 
each month. The shaded band around the median line indicates the 80% to 20% exceedance probability range in year-
to-year variation. PAWC = plant available water capacity of given soil profile. 

Seldom is soil uniform within a single paddock, let alone across entire districts. Without the 
homogenising input of irrigation to alleviate water limitations (and associated high inputs of 
fertilisers to alleviate nutrient limitations), yields from low-input rainfed cropping are typically 
much more variable (both across years and locations) than yields from irrigated agriculture. 
Furthermore, the capacity of the soil to supply stored water varies with soil type, and it also 
depends on crop type and variety because each crop’s root system has a different ability to access 
water, particularly deep in the profile. This makes it harder to make generalisations about the 
viability of rainfed cropping in the Southern Gulf catchments as farm performance (e.g. yields and 
GMs) is much more sensitive to slight variations in local conditions. Rigorous estimates of rainfed 
crop performance, on which investment decisions could be confidently made, would require 
detailed localised soil mapping and crop trials. 

Despite the challenges described above, recent efforts have identified potential opportunities for 
rainfed farming using higher-value crops, such as pulses or cotton, in northern Australia. A 
preliminary APSIM assessment of the potential for rainfed cotton in the Katherine region 
suggested that mean lint yields of 2.5 to 3.5 bales per ha may be possible at a range of locations in 
the vicinity of the Southern Gulf catchments (Yeates and Poulton, 2019). However, there was very 
high variability in median yields between farms (1–5 bales/ha), depending on management and 
soil type. 

4.3.4 Irrigated crop response and performance metrics 

Crops that are fully irrigated can yield substantially more than rainfed crops. Figure 4-8 shows how 
modelled yields for grain sorghum grown on Vertosols in the Southern Gulf catchments increase as 
more water becomes available to alleviate water limitations and meet increasing proportions of 
crop demand. With sufficient irrigation, yields are highest for crops grown over the dry season 

Influence of planting date on yield - kandosol
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For more information on this figure please contact CSIRO on enquiries@csiro.au

when radiation tends to be less limiting comparing plateau of lines in Figure 4-8a and Figure 4-8b. 
For wet-season sowing, unirrigated yields can approach fully irrigated yields in good years (yields 
exceeded in the top 20% of years, marked by the upper shaded range in Figure 4-8a). However, 
irrigation allows greater flexibility in sowing dates, allows sowing in the dry season too (for crops 
that would then grow through the wet season) and generates more reliable (and higher median) 
yields. 

The simulations did not seek to ‘optimise’ supplemental irrigation strategies in years where 
available water was insufficient to maximise crop yields; irrigators would need to make those 
decisions in years where available water was lower than total crop demand. A key advantage of 
irrigated dry-season cropping in northern Australia is that the availability of water in the soil 
profile and surface water storages is largely known at the time of planting (in the early wet season; 
Table 4-5). This means irrigators have good advance knowledge for planning how much area to 
plant, which crops to grow and which irrigation strategies to use, particularly in years where they 
have insufficient water to fully irrigate all fields. A mix of irrigation approaches could be used, such 
as expanding the scale of a core irrigated cropping area with other less intensively farmed areas, 
opportunistic rainfed cropping, opportunistic supplemental irrigation, opportunistic sequential 
cropping and/or adjusting the area of fully irrigated crops grown to match available water supplies 
that year. 

(a) 1 February sowing (wet season) 

 

(b) 1 August sowing (dry season) 

 



Figure 4-8 Influence of available irrigation water on grain sorghum yields for planting dates of (a) 1 February and (b) 
1 August, for a Vertosol with a Gregory climate 

Estimates are from 100-year Agricultural Production Systems Simulator simulations. The shaded band around the 
median line indicates the 80% to 20% exceedance probability range in year-to-year variation. Rainfed production is 
indicated by the zero point, where no allocation is available for irrigation. 

Measures of farm performance (in terms of yields, water use and GMs) are presented for the 19 
cropping options that were evaluated (Table 4-4). Given the limited commercial irrigated farming 
currently occurring in the Southern Gulf catchments that can provide real-world data, estimates of 
crop water use and yields should be considered as indicative, and to have a possible 20% margin of 
error at the catchment scale (with further variation expected between farms and fields). The 
measures of performance should be considered as an upper bound of what could be achieved 
under best-practice management after learning and adapting to location-specific conditions. 

GMs are a key partial metric of farm performance but should not be treated as fixed constants 
determined by the cropping system alone. They are a product of the farming and business 

Influence of available water on yield for sorghum planted 1 Feb
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\5_Agriculture_economics\4_S_Gulf\4_Data\4_APSIMmodelling\SOGWRA-Charts_APSIM_v3.xlsx
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Influence of available water on yield for sorghum planted 1 Aug
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6 



management decisions made by individual farmers, input prices, commodity prices and market 
opportunities (details on calculation of GMs are in Webster et al., 2024). As such, the GMs 
presented in Table 4-6 should be treated as indicative of what might be attained for each cropping 
option once its sustainable agronomic potential has been achieved. Any divergence from 
assumptions about yields and costs would flow through to GM values, as would the consequences 
of any underperformance or overperformance in farm management. It is unrealistic to assume 
that the levels of performance in the results below would be achieved in the early years of newly 
established farms, and allowance should be made for an initial period of learning when yields and 
GMs are below their potential (see Chapter 6). Collectively however, the GMs and other 
performance metrics presented here provide an objective and consistent comparison across a 
suite of likely cropping options for the Southern Gulf catchments, and indicate a maximum 
performance that could be achievable for greenfield irrigated development for each of the 
groupings of crops in sections 4.3.5 to 4.3.7. 

4.3.5 Irrigated broadacre crops 







Table 4-6 shows the farm performance (yields, water use and GMs) for the ten broadacre cropping 
options that were evaluated. For crops that were simulated with APSIM, estimates are provided 
for locations with four different soil types associated with climates in the Southern Gulf 
catchments (Kandosol at Westmoreland, Vertosol at Gregory, Chromosol at Kamilaroi and Vertosol 
at Gallipoli) and include measures of variability (expressed in terms of years with yield exceedance 
probabilities of 80%, 50% (median) and 20%). For other crops, yield and water use estimates (and 
resulting GMs) were estimated based on expert experience and climate-informed extrapolation 
from the most similar analogue locations in northern Australia where commercial production 
currently occurs. 
The broadacre cropping options with the best GMs (>$2000/ha) were cotton (both wet-season 
and dry-season cropping), forages (Rhodes grass (Chloris gayana)) and peanuts (on a Chromosol). 
These suggest GMs up to $4500/ha might be achievable for broadacre cropping in the Southern 
Gulf catchments, although not necessarily at scale. 
Simulated yields (and consequent GMs) were generally lowest on the Kandosol and highest on the 
heavy Vertosol because of the increased buffering capacity that a high PAWC clay soil provides 
against hot weather, which triggers water stress even in irrigated crops. The Chromosol yields and 
GMs were slightly lower than the Vertosol due to its lower PAWC. With Vertosols in the Southern 
Gulf catchments there could be drainage challenges (Figure 4-6) that could limit the suitable area 
for farming and may require more careful management than Vertosols that are currently used for 
cotton farming in other parts of Australia. 
A breakdown of the variable costs for growing broadacre crops shows that the largest costs are 
the costs of inputs (mean 28%), farm operations (mean 33%) and marketing (mean 28%) 
(Table 4-7). The input and operations cost categories would have similar dollar values when 
growing the same crop in southern parts of Australia, but the cost category that is higher and thus 
puts northern growers at a disadvantage is market costs (freight and other costs involved in selling 
the crop). Total variable costs consume 84% of the gross revenue generated, which leaves margin 
for profitable farms to be able to temporarily absorb small declines in commodity prices or yields 
without creating severe cashflow problems. 
226 | Water resource assessment for the Southern Gulf catchments 


Table 4-6 Performance metrics for broadacre cropping options in the Southern Gulf catchments: applied irrigation water, crop yield and gross margin (GM) for four 
environments 

Performance metrics indicate the upper bound that could be achieved after best management practices for Southern Gulf catchments environments had been identified and 
implemented. All options are for dry-season (DS) irrigated crops sown between March and May (end of the wet season (WS)), except for the WS cotton, sown in mid-February and 
DS cotton sown in mid-June. Our modelled results suggest that dry-season planting of cotton in mid-June at Gallipoli led to a high incidence of crop failure and is not shown. 
Variance in yield estimates from Agricultural Production Systems sIMulator (APSIM) simulations is indicated by providing 80%, 50% (median) and 20% probability of exceedance 
values (Y80%, Y50% and Y20%, respectively), together with associated applied irrigation water (including on-farm losses) and GMs in those years. The lower-range yields (Y80% 
exceedance) occur in most years, while the upper-range Y20% yields only occur in the most exceptional upper 20% of years. Note that applied irrigation water is not always higher 
in years with higher yields (Y20%). ‘na’ indicates 20% and 80% exceedance estimates that were not applicable because APSIM outputs were not available and expert estimates of 
just the median yield and water use were used instead. Peanut is omitted for the Vertosol location because of the practical constraints of harvesting root crops on clay soils. 
Freights costs assume processing near Cloncurry for cotton and Townsville for peanut, and that hay is sold locally. No crop model was available for sesame or hemp, so indicative 
estimates for the catchments were used. Cotton yields and prices are for lint bales (227 kg after ginning), not tonnes, and account for a lint turnout of 40% and a cotton seed price 
of $280/t. PAWC = plant available water capacity. 

CROP 

APPLIED IRRIGATION WATER 

CROP YIELD 

YIELD UNIT 

PRICE 

VARIABLE COSTS 

TOTAL 
REVENUE 

GROSS MARGIN 



(ML/ha/y) 

(yield units) 



($/unit) 

($/ha/y) 

($/ha/y) 



($/ha/y) 





Y80% 

Y50% 

Y20% 

Y80% 

Y50% 

Y20% 









Y80% 

Y50% 

Y20% 

Red Kandosol (129 mm PAWC), Westmoreland climate (~780 mm annual rainfall) 

Cotton (WS) 

4.5 

5.3 

5.7 

8.6 

9.4 

10 

bales/ha 

700 

4,159 

7,415 

2,784 

3,256 

3,683 

Cotton (DS) 

5.0 

5.4 

5.9 

3.7 

5.0 

6 

bales/ha 

700 

3,230 

3,939 

–24

708 

1,554 

Sorghum (grain) 

5.2 

5.6 

6.0 

8.5 

9.0 

10 

t/ha 

350 

3,779 

3,164 

–641

–615

–597

Mungbean 

3.6 

3.9 

4.3 

1.5 

1.8 

2 

t/ha 

1,200 

1,417 

1,958 

323

540 

720

Chickpea 

2.2 

2.3 

2.6 

0.3 

0.3 

0 

t/ha 

750 

1,019 

254 

–776

–765

–732

Soybean 

5.6 

5.9 

6.4 

3.3 

3.5 

4 

t/ha 

650 

2,139 

2,265 

107

125 

182

Peanut 

4.0 

4.5 

4.9 

5.1 

5.5 

6 

t/ha 

1,000 

4,849 

5,455 

483 

607 

810 

Rhodes grass (hay) 

13.7 

15.3 

16.9 

38.1 

39.2 

41 

t/ha 

220 

5,672 

8,624 

3,032 

2,952 

3,005 

Maize 

5.5 

5.8 

6.1 

8.9 

9.3 

10 

t/ha 

380 

3,857 

3,530 

–291

–328

–308

Heavy Vertosol (212 mm PAWC), Gregory climate (~540 mm annual rainfall) 

Cotton (WS) 

4.1 

4.7 

5.2 

9.7 

10.7 

11 

bales/ha 

700 

3,857 

8,425 

3,986 

4,536 

4,950 




CROP 

APPLIED IRRIGATION WATER 

CROP YIELD 

YIELD UNIT 

PRICE 

VARIABLE COSTS 

TOTAL 
REVENUE 

GROSS MARGIN 



(ML/ha/y) 

(yield units) 



($/unit) 

($/ha/y) 

($/ha/y) 



($/ha/y) 





Y80% 

Y50% 

Y20% 

Y80% 

Y50% 

Y20% 









Y80% 

Y50% 

Y20% 

Cotton (DS) 

5.2 

5.9 

6.3 

5.0 

6.8 

9 

bales/ha 

700 

3,889 

5,354 

1,066 

2,096 

3,378 

Sorghum (grain) 

5.2 

5.8 

6.5 

10.0 

10.5 

11 

t/ha 

350 

3,259 

3,671 

358 

298 

348 

Mungbean 

3.2 

3.8 

4.4 

1.6 

1.9 

2 

t/ha 

1,200 

3,373 

2,068 

559 

794 

968 

Chickpea 

3.2 

3.8 

3.9 

1.9 

2.2 

3 

t/ha 

750 

1,275 

1,650 

90 

227 

436 

Soybean 

7.6 

8.6 

9.3 

4.7 

5.0 

5 

t/ha 

650 

1,423 

3,223 

913 

998 

1,109 

Rhodes grass (hay) 

17.6 

20.5 

22.3 

44.9 

45.9 

47 

t/ha 

220 

6,566 

10,096 

3,648 

3,530 

3,474 

Maize 

6.7 

7.2 

7.9 

9.6 

10.0 

10 

t/ha 

380 

3,299 

3,800 

445 

501 

544 

Chromosol (92 mm PAWC), Kamilaroi climate (~577 mm) 

Cotton (WS) 

4.7 

5.4 

5.8 

9.3 

10.5 

12 

bales/ha 

700 

3,697 

8,268 

3834 

4,571 

5,195 

Cotton (DS) 

6.3 

6.9 

7.4 

4.7 

6.6 

8 

bales/ha 

700 

3,183 

5,197 

815 

2,014 

2,892 

Sorghum (grain) 

5.7 

6.4 

6.9 

10.5 

11.1 

12 

t/ha 

350 

3,159 

3,885 

657 

726 

809 

Mungbean 

3.5 

4.1 

4.5 

1.6 

1.9 

2 

t/ha 

1,200 

1,253 

2,101 

608 

848 

1,090 

Chickpea 

2.4 

2.7 

3.3 

0.8 

1.1 

1 

t/ha 

750 

1,128 

788 

–445

–340

–218

Soybean 

7.3 

7.8 

8.4 

4.0 

4.2 

4 

t/ha 

650 

1,949 

2,703 

687 

754 

826 

Peanut 

5.3 

5.8 

6.2 

6.3 

6.9 

7 

t/ha 

1,000 

4,766 

6,900 

1,793 

2,134 

2,359 

Rhodes grass (hay) 

20.0 

22.4 

24.3 

45.2 

46.3 

47 

t/ha 

220 

6,946 

10,195 

3,319 

3,249 

3,175 

Maize 

6.5 

6.9 

7.3 

9.3 

9.8 

10 

t/ha 

380 

2,937 

3,706 

700 

769 

833 

Light Vertosol (146 mm PAWC), Gallipoli climate (~420 mm) 

Cotton (WS) 

4.3 

4.9 

5.4 

5.6 

7.6 

9 

bales/ha 

700 

3,324 

5,984 

1414 

2,660 

3,581 

Sorghum (grain) 

6.5 

7.4 

7.9 

11.1 

11.6 

12 

t/ha 

350 

3,521 

4,076 

499 

555 

603 

Mungbean 

4.0 

4.5 

5.0 

1.8 

2.0 

2 

t/ha 

1,200 

1,306 

2,212 

700 

906 

1,104 

Chickpea 

3.5 

4.1 

4.5 

1.9 

2.3 

3 

t/ha 

750 

1,416 

1,692 

117 

276 

538 

Soybean 

8.8 

9.4 

10.1 

4.8 

5.0 

5 

t/ha 

650 

2,213 

3,240 

947 

1,026 

1,082 




CROP 

APPLIED IRRIGATION WATER 

CROP YIELD 

YIELD UNIT 

PRICE 

VARIABLE COSTS 

TOTAL 
REVENUE 

GROSS MARGIN 



(ML/ha/y) 

(yield units) 



($/unit) 

($/ha/y) 

($/ha/y) 



($/ha/y) 





Y80% 

Y50% 

Y20% 

Y80% 

Y50% 

Y20% 









Y80% 

Y50% 

Y20% 

Rhodes grass (hay) 

24.4 

22.4 

24.4 

45.0 

46.3 

47 

t/ha 

220 

6,829 

10,179 

4,575 

3,350 

3,327 

Maize 

6.1 

8.0 

8.5 

9.7 

10.2 

11 

t/ha 

380 

3,256 

3,895 

203 

638 

675 

General estimate for Southern Gulf catchments (not soil specific) 

Sesame 

na 

5.3 

na 

na 

0.9 

na 

t/ha 

1,300 

2,041 

1,170 

na 

–871

na 

Hemp (grain seed) 

na 

5.0 

na 

na 

1.1 

na 

t/ha 

3,150 

2,519 

3,465 

na 

946 

na 






Table 4-7 Breakdown of variable costs relative to revenue for broadacre crop options 

The first eight crops (Cotton (WS) to Rhodes grass) are for the Chromosol, Kamilaroi climate (intermediate 
performance), and the last three crops are for general catchment estimates. ‘Input’ costs are mainly for fertilisers, 
herbicides and pesticides; the cost of farm ‘operations’ includes harvesting; ‘labour’ costs are the variable component 
(mainly seasonal workers) not covered in fixed costs (mainly permanent staff); ‘market’ costs include levies, 
commission and transport to the point of sale. WS = wet season; DS = dry season. 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
Risk analyses were conducted for the two broadacre crops with the highest GMs: cotton and 
forages. The risk analysis used a narrative approach, where variable values with the potential to be 
different from those used in the GMs were varied and new GMs calculated. The narrative 
approach allows the impact of those variables to be determined. The cotton analysis explored the 
sensitivity of GMs to opportunities and challenges created by changes in cotton lint prices, crop 
yields and distance to the nearest gin (Table 4-8). Results show that high recent cotton prices 
(about $800/bale through 2022) have created a unique opportunity for those looking to establish 
new cotton farms in NT locations like the Victoria catchment, since growers could transport cotton 
to distant gins or produce suboptimal yields and still generate GMs above $3000/ha. At lower 
cotton lint prices, a local gin becomes more important for farms to remain viable. High cotton 
prices and the opening of a cotton gin 30 km north of Katherine in December 2023 have reduced 
some of the risk involved in learning to grow cotton as GMs increase from both these 
developments. At high yields and prices, the returns per megalitre of irrigation water may favour 
growing a single cotton crop per year, instead of committing limited water supplies to sequential 
cropping with a dry-season crop (that would likely provide lower returns per megalitre and be 
operationally difficult/risky to sequence). 




Table 4-8 Sensitivity of cotton crop gross margins ($/ha) to variation in yield, lint prices and distance to gin 

The base case is the Gregory heavy Vertosol (Table 4-6) and is highlighted for comparison. The gin locations 
considered are a local gin near a new cotton farming region in the Southern Gulf catchments near Gregory, a 
hypothetical gin in Cloncurry, and the existing gin in Emerald, Queensland. Cotton lint prices include a low price for 
2015–2020 ($580/bale), a mean price for 2020–2024 ($700/bale) and a high price for 2015–2020 ($900/bale). Effects 
of a lower yield are also tested (the base case of 10.7 bales/ha for wet-season cropping versus the 6.8 bales/ha 
estimated as the dry-season yield for this location). 

FREIGHT COST/TONNE 
(DISTANCE TO GIN) 

COTTON CROP GROSS MARGIN ($/ha) 



LINT PRICE = $580/bale 

LINT PRICE = $700/bale 

LINT PRICE = $900/bale 



YIELD 

YIELD 

YIELD 



10.7 
bales/ha 

6.8 
bales/ha 

10.7 
bales/ha 

6.8 
bales/ha 

10.7 
bales/ha 

6.8 
bales/ha 

$13 (50 km to local gin) 

3732 

1613 

5016 

2429 

7156 

3789 

$92 (330 km to Cloncurry gin) 

3532 

1308 

4536 

2124 

6676 

3484 

$243 (1250 km to Emerald gin) 

2335 

725 

3619 

1541 

5759 

2901 



The narrative risk analysis for irrigated forages also looked at the sensitivity of farm GMs to 
variations in hay price and distance to markets, but here focuses on the issues of local supply and 
demand (Table 4-9). Forages, such as Rhodes grass, are a forgiving first crop to grow on greenfield 
farms as new farmers gain experience of local cropping conditions and ameliorate virgin soils while 
producing a crop with a ready local market in cattle. While there are limited supplies of hay in the 
region, growers may be able to sell hay at a reasonable price, given the large amount of beef 
production in the Southern Gulf catchments and challenges of maintaining livestock condition 
through the dry season, when the quality of native pastures is low. The scale of unmet local 
demand for hay limits opportunities for expansion of hay production without depressing local 
prices and/or having to sell hay further away, both of which lead to rapid declines in GMs (to 
below zero in many cases; Table 4-9). Another opportunity for hay is for feeding to cattle during 
live export, which could be integrated into an existing beef enterprise to supply their own live 
export livestock; this would require the hay to be pelleted. Section 4.3.9 considers how forages 
could be integrated into local beef productions systems for direct consumption by livestock within 
the same enterprise. 

Table 4-9 Sensitivity of forage (Rhodes grass) crop gross margins ($/ha) to variation in yield and hay price 

The base case is the Gregory heavy Vertosol (Table 4-6) and is highlighted for comparison. Transporting the hay 
further distances would increase opportunities for finding counter-seasonal markets paying higher prices, but this 
would be rapidly offset by higher freight costs. 

FREIGHT COST/TONNE 
(DISTANCE TO DELIVER) 

FORAGE CROP GROSS MARGIN ($/ha) 



HAY PRICE/TONNE 



$150 

$250 

$350 

$20 (local) 

317 

3530 

9495 

$92 (330 km to Cloncurry) 

–1708

1505 

7471 

$243 (1250 km to Emerald) 

–9917

–6704

–738




4.3.6 Irrigated horticultural crops 

Table 4-10 shows estimates of potential performance for a range of horticultural crop options in 
the Southern Gulf catchments. Upper potential GMs for annual and tree horticulture are about 
$5000 per ha per year). Capital costs of farm establishment and operating costs increase as the 
intensity of farming increases, so ultimate farm financial viability is not necessarily better for 
horticulture compared to broadacre crops with lower GMs (see Chapter 6). Note also that 
perennial horticulture crops typically require more water than annual crops because irrigation 
occurs for a longer period each year (mean of 8.5 compared to 4.4 ML per ha per year, 
respectively in Table 4-10); this also, indirectly, affects capital costs of development since 
perennial crops require a larger investment in water infrastructure compared to annual crops to 
support the same cropped area. 

Table 4-10 Performance metrics for horticulture options in the Southern Gulf catchments: annual applied irrigation 
water, crop yield and gross margin 

Applied irrigation water includes losses of water during application. Horticulture is most likely to occur on well-drained 
Kandosols. Product unit prices listed are for the dominant top grade of produce, but total yield was apportioned 
among lower graded/priced categories of produce as well in calculating total income. Transport costs assume sales of 
total produce are split among southern capital markets in proportion to their size. Applied irrigation water accounts 
for application losses assuming efficient pressurised micro irrigation systems. KP = Kensington Pride mangoes; PVR = 
new high-yielding mangoes varieties with plant variety rights (e.g. Calypso). 

CROP 

APPLIED IRRIGATION 
WATER 

CROP YIELD 

PRICE 

PRICING UNIT 

VARIABLE 
COSTS 

TOTAL 
REVENUE 

GROSS 
MARGIN 



(ML/ha/y) 

(t/ha/y) 

($/unit) 

(unit) 

($/ha/y) 

($/ha/y) 

($/ha/y) 

Row crop fruit and vegetables, annual horticulture (less capital intensive) 

Rockmelon 

5.0 

25.0 

28 

15 kg tray 

43,216 

44,000 

784 

Watermelon 

5.7 

47.0 

450 

500 kg box 

52,321 

42,300 

–10,021

Capsicum 

3.0 

32.0 

19 

8 kg carton 

71,158 

76,000 

8,842

Onion 

4.0 

30.0 

15 

10 kg bag 

36,906 

41,850 

4,944 

Fruit trees, perennial horticulture (more capital intensive) 

Mango (KP) 

7.4 

9.3 

24 

7 kg tray 

22,023 

28,398 

6,375 

Mango (PVR) 

7.4 

17.5 

21 

7 kg tray 

42,786 

47,250 

4,464 

Lime 

10.8 

28.5 

18 

5 kg carton 

94,913 

100,890 

5,977



Crop yields and GMs can vary substantially among varieties, as is demonstrated in Table 4-10 for 
mangoes (Mangifera indica). Mango production is well established in multiple regions of northern 
Australia, including in the Darwin, Douglas–Daly and Katherine regions of the NT, Bowen, the 
lower Burdekin and the Mareeba–Dimbulah Irrigation Area in Queensland. For example, the well-
established Kensington Pride mangoes typically produce 5 to 10 t/ha while newer varieties (such 
as Calypso) can produce 15 to 20 t/ha. New varieties are likely to be released with plant variety 
rights (PVR) accreditation and are denoted as such. Selection of varieties also needs to consider 
consumer preferences and timing of harvest relative to seasonal gaps in market supply that can 
offer premium prices. 

Prices paid for fresh fruit and vegetables can be extremely volatile (Figure 4-9) because produce is 
perishable and expensive to store, and because regional weather patterns can disrupt target 


timing of supply, which can result in unintended overlaps or gaps in combined supply between 
regions. This creates regular fluctuations between oversupply and undersupply, against inelastic 
consumer demand, to the extent that prices can fall so low at times that it would cost more to 
pick, pack and transport produce than farms receive in payment. Within this volatility are some 
counter-seasonal windows in southern markets (where prices are typically higher) that northern 
Australian growers can target. 



Figure 4-9 Fluctuations in seedless watermelon prices at Melbourne wholesale markets from April 2020 to February 
2023 

Percentage change information available; however, prices are commercially sensitive and not available. 

Source: ABARES (2023) 

Horticultural enterprises typically run on very narrow margins, where about 90% of gross revenue 
would be required just to cover variable costs of growing and marketing a crop grown in the 
Southern Gulf catchments. This makes crop GMs extremely sensitive to fluctuations in variable 
costs, yield and produce prices, amplifying the effect of already volatile prices for fresh fruit and 
vegetables. The majority of the variable costs of horticultural production occur from harvest 
onwards, mainly in freight, labour and packaging. This affords the opportunity to mitigate losses if 
market conditions are unfavourable at the time of harvest, since most costs can be avoided (at the 
expense of foregone revenue) by not picking the crop. 

The narrative risk analysis for horticulture used the crop with the lowest GM (watermelons 
(Citrullus lanatus) Table 4-10, to illustrate how opportunities for reducing freight costs and 
targeting periods of higher produce prices could improve GMs to find niches for profitable farms 
(Table 4-11). Reducing freight costs by finding backloading opportunities or concentrating on just 
the smaller closest southern capital city market of Brisbane would substantially improve GMs, but 
a higher price than average is needed to generate positive GMs. The base case already assumed 
that growers in the Southern Gulf catchments would target the predictable seasonal component 
of watermelon price fluctuations (Figure 4-9), but any further opportunity to attain premiums in 
pricing could help convert an unprofitable baseline case into a profitable one. This example also 
highlights the issue that while there may be niche opportunities that allow an otherwise 

Influence of available water on yield for sorghum planted 1 Aug
https://www.agriculture.gov.au/abares/data/weekly-commodity-price-update/australian-horticulture-prices#daff-page-main
For more information on this figure please contact CSIRO on enquiries@csiro.au

unprofitable enterprise to be viable, the scale of those niche opportunities also then limits the 
scale to which the industry in that location could expand; for example: (i) there is a limit to the 
volume of backloading capacity at cheaper rates, (ii) supplying produce to only the closest market 
excludes the largest markets (e.g. accessing the larger Sydney and Melbourne markets remains 
non-viable except when prices are high; Table 4-11) and (iii) chasing price premiums restricts the 
seasonal windows into which produce is sold or restricts markets to smaller niches that target 
specialised product specifications. Niche opportunities are seldom scalable, particularly in 
horticulture, which is partly why horticulture in any region usually involves a range of different 
crops (often on the same farm). 

Table 4-11 Sensitivity of watermelon crop gross margins ($/ha) to variation in melon prices and freight costs 

The base case (Table 4-10) is highlighted for comparison. 

FREIGHT COST/TONNE 



WATERMELON PRICE (PERCENTAGE DIFFERENCE FROM BASE PRICE) 

(MARKET LOCATION) 









$210/t 

$337 (–25%) 

$450 (BASE PRICE) 

$675 (+50%) 

$900 (+100%) 

$342 (backloading to Brisbane) 



–10,836

–1,702

16,487 

34,676 

$429 (close market: Brisbane) 



–14,925

–5,791

12,398 

30,587 

$519 (all capital cities) 



–19,155

–10,021

8,168 

26,357 

$559 (Melbourne) 



–21,035

–11,901

6,288 

24,477 



The risk analysis also illustrates just how much farm financial metrics like GMs amplify fluctuations 
to input costs and commodity prices to which they are exposed. For horticulture, far more than 
broadacre agriculture, it is very misleading to look just at a single ‘median’ GM for the crop, 
because that is a poor reflection of what is going on within an enterprise. For example, a –50% to 
+100% variation in watermelon prices would result in theoretical annual GMs fluctuating between–$19.155/ha and $26,357/ha (Table 4-11). Although, in practice, potentially negative GMs couldbe greatly mitigated (by not harvesting the crop), this still creates cashflow challenges in managingyears of negative returns between years of windfall profits. This amplified volatility is anotherreason that horticultural farms often grow a mix of produce (as a means of spreading risk). For rowcrop production, another common way of mitigating risk is using staggered planting through theseason, so that subsequent harvesting and marketing are spread out over a longer target windowto smooth out some of the price volatility.

4.3.7 Plantation tree crops 

Estimates of annual performance for African mahogany (Khaya ivorensis) are provided in Table 
4-12. The best available estimates were used in the analyses, but information on plantation treeproduction in northern Australia is often commercially sensitive and/or not independentlyverified. The measures of performance presented, therefore, have a low degree of confidence andshould be treated as broadly indicative, noting that actual commercial performance could beeither lower or higher.




Table 4-12 Performance metrics for plantation tree crop options in the Southern Gulf catchments: annual applied 
irrigation water, crop yield and gross margin 

Yields are values at final harvest and pricing unit is for an 800 kg cube, with 10% of the African mahogany yield as 
marketable cubes. Other values are annual averages assuming a 20-year life cycle of the crop (representing the 
idealised ultimate steady state of an operating farm that was set up with staggered plantings for a steady stream of 
harvests). No discounting is applied to account for the substantial timing offset between when costs are incurred and 
revenue is received; any investment decision would need to take that into account. African mahogany performance is 
for unirrigated production. 

CROP 

CROP 
LIFE 
CYCLE 

APPLIED IRRIGATION 
WATER 

CROP 
YIELD AT 
HARVEST 

PRICE 

PRICING 
UNIT 

VARIABLE 
COSTS 

TOTAL 
REVENUE 

GROSS 
MARGIN 



(y)

(ML/ha/y) 

(t/ha) 

($/unit) 



($/ha/y) 

($/ha/y) 

($/ha/y) 

African mahogany 

20 

unirrigated 

160 

4000 

cube 

1103 

4000 

2897 



Plantation forestry has long life cycles with low-intensity management during most of the growth 
cycle, so variable costs typically consume less of the gross revenue (28%) than for broadacre or 
horticultural farming. However, production systems with long life cycles have additional risks over 
annual cropping: there is a much longer period between planting and harvest for adverse events 
to affect the yield quantity and/or quality, prices of inputs and harvested products could change 
substantially over that period, and market access and arrangements with buyers could change. 
The long lags from planting to harvest also mean that potential investors need to consider other 
similar competing pipeline developments (that may not be obvious because they are not yet 
selling product) and long-term future projections of supply and demand (for when their own 
plantation will start to be harvested and enter supply chains). The cashflow challenges are also 
significant given the long-term outlay of capital and operating costs before any revenue is 
generated. Carbon and other externality credits might be able to assist with some early cashflow 
(e.g. if the ‘average’ state of the plantation, from planting to harvest, stores more carbon than the 
vegetation it replaced). 

4.3.8 Cropping systems 

This section evaluates the types of cropping systems (crop species × growing season × resource 
availability × management options) that are most likely to be profitable in the Southern Gulf 
catchments based on the above analyses of GMs, information from companion technical reports in 
this Assessment, and cropping knowledge from climate-analogous regions (relative to local 
biophysical conditions). Cropping system choices could include growing a single crop during a 12-
month period, or growing more than one crop – commonly referred to as sequential, double or 
rotational cropping. Since many of the issues for single cropping options were covered earlier, this 
section focuses on sequential cropping systems and the mix of cropping options that might be 
grown in sequence on a unit of land in the Southern Gulf catchments. 

Cropping system considerations 

Selecting two or more crops to grow in sequence increases the complexity, beyond the issues 
already discussed, in finding and adapting individual cropping options for the Southern Gulf 
catchments. The rewards from successfully growing crops in sequence (versus single cropping) can 
be substantial if additional net annual revenue can be generated from the same initial capital 


investment (to establish the farm). To find viable mixes of cropping options for the Southern Gulf 
catchments, developers will need to consider each of the following four key factors. 

Markets 

Whether growing a single crop or doing sequential cropping, the choice of crop(s) to grow is 
market driven. As the price received for different crops fluctuates, so too will the crops grown. In 
the Southern Gulf catchments, freight costs, determined by the distance to selected markets, must 
also be considered. A critical scale of production may be needed for a new market opportunity or 
supply chain to be viable (e.g. exporting grains from Townsville would require sufficient economies 
of scale for the required supporting port infrastructure, and shipping routes to be viable). Crops 
such as cotton, peanut and sugarcane (Saccharum officinarum) require a processing facility. A 
consistent and critical scale of production is required for processing facilities to be viable. 
Transport costs of raw cotton from the Southern Gulf catchments to the closest gin in Emerald 
would be offset by access to a gin locally and go a long way to improving the viability of cotton 
production (Table 4-8). 

Most horticultural production from the Southern Gulf catchments would be sent to capital city 
markets, often using refrigerated transport. Horticultural production in the Southern Gulf 
catchments would have to accept a high freight cost compared to the costs faced by producers in 
southern parts of Australia. The competitive advantage of horticultural production in the Southern 
Gulf catchments is that higher market prices can be achieved from ‘out-of-season’ production 
compared to large horticultural production areas in southern Australia. Annual horticultural row 
crops, such as melons, would be grown sequentially, for example with fortnightly planting over 3 
to 4 months, to reduce risk of exposure to low market prices and to make it more likely that very 
high market prices would be achieved for at least some of the produce. 

Operations 

Sequential cropping can require a trade-off against sowing at optimal times to allow crops to be 
grown in a back-to-back schedule. This trade-off could lead to lower yields from planting at 
suboptimal times. For annual horticultural crops there would be additional trade-offs in the 
seasonal window over which produce can be sent to market (affecting opportunities to target 
seasonal peaks in prices and to use staggered planting dates to mitigate risks from price 
fluctuations). 

Growing crops sequentially depends on timely transitions between the crops, and selecting crops 
that are agronomically and operationally compatible with each other, including growing seasons 
that reliably fit together in the available cropping windows. In the catchments’ variable and often 
intense wet season, rainfall increases operational risk because of reduced trafficability and the 
subsequent limited ability to conduct timely operations. A large investment in machinery (either 
multiple or larger machines) could increase the area that could be planted per day when fields are 
trafficable within a planting window. With sequential cropping, additional farm machinery and 
equipment may be required where there are crop-specific machinery requirements, or to help 
complete operations on time when there is tight scheduling between crops. Any additional capital 
expenditure on farm equipment would need to be balanced against the extra net farm revenue 
generated. 


Sequential cropping can also lead to a range of cumulative issues that need careful management, 
for example: (i) build-up of pests, diseases (particularly if the sequential cropping is of the same 
species or family) and weeds; (ii) pesticide resistance; (iii) increased watertable depth; and (iv) soil 
chemical and structural decline. Many of these challenges can be anticipated before beginning 
sequential cropping. Integrated pest, weed and disease management would be essential when 
multiple crop species are grown in close proximity (adjacent fields or farms). Many of these pests 
and controls are common to several crop species where pests (e.g. aphids) move between fields. 
Such situations are exacerbated when the growing seasons of nearby crops partially overlap or 
when sequential crops are grown, because both scenarios create ‘green bridges’ that facilitate the 
continuation of pest life cycles. When herbicides are required, it is critical to avoid products that 
could damage a susceptible crop the following season or sequentially. 

Water 

Sequential cropping leads to a higher annual crop water demand (versus single cropping) because: 
(i)the combined period of cropping is longer, (ii) it includes growing during the dry season in theSouthern Gulf catchments and (iii) PAW at planting will have been depleted by the previous crop.
Typically, an additional 1 ML/ha on well-drained soils, and 1.5 ML/ha on clays, is required forsequential cropping relative to the combined water requirements of growing each of those cropsindividually (with the same sowing times). This additional water demand needs to be accountedfor in initial farm planning, particularly where on-farm water storage or dry-season waterextraction is required.

Irrigating using surface water in the Southern Gulf catchments would face issues with the 
reliability and the timing of water supplies. Monitored river flows need to be sufficient to allow 
pumping into on-farm storages for irrigation (i.e. to meet environmental flow and river height 
requirements). The timing of water availability is analysed in the companion technical report on 
river model scenario analysis (Gibbs et al., 2024). The availability of water for extraction each wet 
season affects the options for sequencing a second crop. 

Soils 

The largest arable areas in the Southern Gulf catchments are the cracking clay Vertosols (SGG 9, 
marked ‘A’ and ‘D’ in Figure 4-3), principally on the floodplains and alluvial plains of the 
Armraynald Plain and Barkly Tableland. Friable, non-cracking clay soils (SGG 1 and 2, marked ‘B’ 
and ‘C’) and loamy soils (SGG 4, marked ‘F’) make up substantial areas (Figure 4-3). There are good 
analogues of these environments in the Southern Gulf catchments in successful irrigated farming 
areas in other parts of northern Australia. Katherine is indicative of farming systems and potential 
crops grown on well-drained loamy soils irrigated by pressurised systems, and the Burdekin River 
Irrigation Area and Ord River Irrigation Area are indicative of furrow irrigation on heavy clay soils. 

The good wet-season trafficability of the well-drained loamy Kandosols permits timely cropping 
operations and would enhance the implementation of sequential cropping systems. However, 
Kandosols also present some constraints for farming. Kandosols are inherently low in organic 
carbon, nitrogen, potassium, phosphorus, sulfur and zinc, and supplementation with other 
micronutrients (boron, copper and molybdenum) is often required. Very high fertiliser inputs are 
therefore required at first cultivation. Due to the high risk of leaching of soluble nutrients (e.g. 
nitrogen and sulfur) during the wet season, in-crop application (multiple times) of the majority of 


crop requirement for these nutrients is necessary (Yeates, 2001). In addition, high soil 
temperatures and surface crusting combined with rapid drying of the soil at seed depth reduce 
crop establishment and seedling vigour for many broadacre species sown during the wet season 
and early dry season, for example, maize, soybean (Glycine max) and cotton (Abrecht and Bristow, 
1996; Arndt et al., 1963). 

In contrast, the cracking clay Vertosols have poor trafficability following rainfall (Figure 4-6) 
inundation or irrigation, disrupting cropping operations. Farm design is a major factor on cracking 
clay soils and needs to minimise flooding of fields from nearby waterways, ensure prompt runoff 
from fields after irrigation or rain events, and ensure that farm roads maintain access to fields. 
Timely in-field bed preparation can reduce delays in planting. Clay soils also have some 
advantages, particularly in costs of farm development by allowing lower-cost gravity-fed surface 
irrigation (versus pressurised systems) and on-farm storages (where expensive dam lining can be 
avoided if soils contain sufficient clay) (see companion technical report on surface water storage, 
Yang et al., 2024). Clay soils also typically have greater inherent fertility than loamy soils, but initial 
sorption by clay means that phosphorus requirements can be high for virgin soils in the first 2 
years of farming. 

Potentially suitable cropping systems 

Potential crop species that could be grown as a single crop per year were identified and rated for 
the Southern Gulf catchments (Table 4-13) based on indicators of farm performance presented 
above (yields, water use and GMs), together with considerations of growing season, experiences 
at climate-analogous locations, past research, and known market and resource limitations and 
opportunities. Many of these crops currently have small to medium high-value markets, hence 
they are sensitive to Australian and international supply. Annual horticulture, cotton, peanut and 
forages are the most likely to generate returns that could exceed farm development and growing 
costs (Table 4-13). 

Table 4-13 Likely annual irrigated crop planting windows, suitability and viability in the Southern Gulf catchments 

Crops are rated on likelihood of being financially viable: *** = likely at low-enough development costs; ** = less likely 
for single cropping (at current produce prices); * S = marginal but possible in a sequential cropping system. Rating 
qualifiers are coded as L development limitation, M market constraint, P depends on sufficient scale and distance to 
local processor, and B depends on distance to and type of beef (livestock production) activity it is supporting. Farm 
viability depends on the cost at which land and water can be developed and supplied (Chapter 6). na = not applicable. 

WET-SEASON PLANTING (JANUARY TO EARLY MAY) 

DRY-SEASON PLANTING (LATE MARCH TO AUGUST) 

CROP 

RATING 

CROP 

RATING 

Cotton 

*** P 

Annual horticulture 

*** M 

Forages 

*** B 

Cotton 

*** P 

Sugarcane 

*** LP 

Niche grains (e.g. chia, quinoa) 

*** SM 

Peanut (not on clay) 

*** LMP 

na 

na 

Mungbean 

** 

Mungbean 

** 

Maize 

** 

na 

na 

Chickpea 

** 

na 

na 

Rice 

** L 

na 

na 

Sorghum (grain) 

*S

Sorghum (grain) 

*S

Soybean 

*S

Soybean 

*S

Sesame 

*S

Sesame 

*S




Due to good wet-season trafficability on loamy soils, there are many sequential cropping options 
for the Southern Gulf catchments Kandosols (Table 4-14). Given the predominance of broadleaf 
and legume species in many of the sequences (Table 4-14), a grass species is desirable as an early 
wet-season cover crop. Although annual horticulture and cotton could individually be profitable 
(Table 4-13), an annual sequence of the two would be very tight operationally. Cotton would be 
best grown from late January with the need to pick the crop by early August, then destroy cotton 
stubble, prepare land and remove volunteer cotton seedlings. That scheduling would make it 
challenging to fit in a late-season melon crop, which would need to be sown by late August to 
early September. Similar challenges would occur with cotton followed by mungbean or grain 
sorghum. 

Table 4-14 Sequential cropping options for Kandosols 

WET-SEASON PLANTING, 
DECEMBER TO EARLY MARCH 

DRY-SEASON PLANTING, 
MARCH TO AUGUST 

CROP 

GROWING SEASON 

CROP 

GROWING SEASON 

Mungbean 

Early February to late April 

Annual horticulture 

Mid-May to late October 

Sorghum 
(grain) 

January to April 

Peanut (not on 
clay) 

January to April or 

February to May 

Cotton 

Late January to early August 

Mungbean 

Mid-August to late October 

Sorghum (grain) 

Mid-August to mid-November 

Forage/silage 

Mid-August to early November; 
cut then retained as wet-season 
cover crop 

Mungbean 

Early February to late April 

Cotton 

Early May to early November 

Mungbean 

Peanut 

Sesame 

Soybean 

Early February to late April 

Early January to late April 

Early January to late April 

Early January to late April 

Maize 

May to October 

Sesame or 

Sorghum 
(grain) 

January to late April 

Chickpea 

May to August 

Mungbean 

Sesame 

Soybean 

Early February to late April 

January to late April 

January to late April 

Grass forage/silage 

May to early November; cut then 
retained as wet-season cover crop 



Fully irrigated sequential cropping on the Southern Gulf catchments Vertosols would likely be 
opportunistic and favour combinations of short-duration crops that can be grown when irrigation 
water reliability is greatest (March to October), for example, annual horticulture (melons), 
mungbean, chickpea and grass forages (growing season 2 to 4 months). Following an unirrigated 
(rainfed) wet-season grain crop with an irrigated dry-season crop could also be possible. However, 
seasonally dependent soil wetting and drying would limit timely planting and the area planted, 
which means that farm yields between years would be very variable. Sorghum (grain), mungbean 
and sesame (Sesamum indicum) are the species most adapted to rainfed cropping due to 
favourable growing season length, and their tolerance to water stress, and higher soil and air 


temperatures. Soil drainage, accessibility and trafficability would limit the scale of farming in the 
wet season within the Southern Gulf catchments (which would restrict opportunities for 
establishing local processors). 

4.3.9 Integrating forage and hay crops into existing beef cattle enterprises 

A commonly held view within the northern cattle industry is that the development of water 
resources would allow irrigated forages and hay to be integrated into existing beef cattle 
enterprises, thereby improving their production and, potentially, their profitability. Currently, 
cattle graze on native pastures, which rely solely on rainfall and any consequent overland flow. 
The quality of these pastures is typically low, and it declines throughout the dry season, so that 
cattle either gain little weight, or even lose weight, during this period. 

Theoretically, the use of on-farm irrigated forage and hay production would allow graziers greater 
options for marketing cattle, such as meeting market liveweight specifications for cattle at a 
younger age, meeting the specifications required for markets different than those typically 
targeted by cattle enterprises in the Southern Gulf catchments and providing cattle that meet 
market specification at a different time of the year. Forages and hay may also allow graziers to 
implement management strategies, such as early weaning or weaner feeding, which should lead 
to flow-on benefits throughout the herd, including increased reproductive rates. Some of these 
strategies are already practised within the Southern Gulf catchments but in almost all incidences 
are reliant on hay or other supplements purchased on the open market. By growing hay on-farm, 
the scale of these management interventions might be increased, at reduced net cost. 
Furthermore, the addition of irrigated feeds may allow graziers to increase the total number of 
cattle that can be sustainably carried on a property. 

Very few cattle enterprises in northern Australia are set up to integrate on-farm irrigation, 
notwithstanding the theoretical benefits. Despite its apparent simplicity, fundamentally altering 
an existing cattle enterprise in this way brings in considerable complexity, with a range of 
unknowns about how best to increase productivity and profitability. The most comprehensive 
guide to what might be possible to achieve by integrating forages into cattle enterprises can be 
found in the guide by Moore et al. (2021), who have used a combination of industry knowledge, 
new research and modelling to consider the costs, returns and benefits. Because there are so few 
on-ground examples, modelling has been used in a number of studies to consider the integration 
of forages and hay into cattle enterprises, summarised by Watson et al. (2021). 

Bio-economic modelling was used in the Assessment to consider the impact of growing irrigated 
forages and hay on a representative beef cattle enterprise on the cracking clays of the ‘Bluegrass 
Browntop Plains’ land type (Southern Gulf NRM, 2016) (see the companion technical report on 
agricultural viability and socio-economics (Webster et al., 2024) for more detail). The enterprise 
was based on a self-replacing cow–calf operation, focused on selling into the live export market. 
Broadly speaking, these enterprise characteristics can be thought of as an owner–manager small 
cattle enterprise within the Southern Gulf catchments. Cattle numbers are lower than that of the 
average property in the Southern Gulf catchments but can be scaled to represent larger herds, 
notwithstanding that economies of scale will result in reduced costs per head in the larger 
enterprises. More detail on the beef industry in the Southern Gulf catchments can be found in 
Section 3.3.3. 


The modelling considered a number of management options: (i) a base enterprise; (ii) base 
enterprise plus buying in hay to feed weaners; growing forage sorghum, an annual forage grass 
species, and feeding either as (iii) stand and graze or (iv) as hay; (v) growing lablab (Lablab 
purpureus), an annual legume, and feeding as stand and graze; and (vi) growing Rhodes grass, a 
perennial tropical grass, and feeding as hay. 

Ideally, production would increase by allowing cattle to reach minimum selling weight at a 
younger age and allowing for greater weight gain during the dry season when animals on native 
pasture alone either lose weight or gain very little weight. The addition of forages and hay also 
allows more cattle to be carried, while still maintaining a utilisation rate of native pastures at 
around 18%. 

A GM per adult equivalent (AE) was calculated as the total revenue from cattle sales minus total 
variable costs (Table 4-15). A profit metric, earnings before interest, taxes, depreciation and 
amortisation (EBITDA), was also calculated as income minus variable and overhead costs, which 
allows performance to be compared independently of financing and ownership structure (McLean 
and Holmes, 2015) and is used in the analysis of NPV. Three sets of beef prices were considered: 

•LOW beef price. Beef prices were set to 275c/kg for males between 12 and 24 months old,
declining across age and sex classes to 134c/kg for cows older than 108 months.
•MED beef price. Beef prices were set to 350c/kg for males between 12 and 24 months old,
declining across age and sex classes to 170c/kg for cows older than 108 months.
•HIGH beef price. Beef prices were set to 425c/kg for males between 12 and 24 months old,
declining across age and sex classes to 206c/kg for cows older than 108 months.


At all three beef prices, total income was highest for the four irrigated forage or hay scenarios 
compared to the two baseline scenarios. 

At MED beef prices, EBITDA was highest for the Rhodes grass hay option at $160,929/year and 
lowest for forage sorghum stand and graze at –$232,238/year. The Rhodes grass hay option and 
the forage sorghum hay option produced the most liveweight sold per year, and the two highest 
incomes. 

An NPV analysis allows consideration of the capital costs involved in development, which are not 
captured in the gross margin or EBITDA. The analysis used two costings ($15,000 and $25,000/ha) 
for the capital costs of development used in the NPV analysis. The NPV analysis (see the 
companion technical report on agricultural viability and socio-economics (Webster et al., 2024)) 
showed that only two irrigated combinations had a positive NPV, that of Rhodes grass hay at MED 
and HIGH beef prices and the lower of the two development costs per hectare. All other 
combinations gave a negative NPV and even the two positive NPVs were low ($18,444 and 
$114,386), suggesting that a decision to irrigate would need to assume beef prices remaining 
strong to be viable. Note that cost of capital theory is complex and investors need to understand 
their weighted average cost of capital and the relative risk of the project compared to the 
enterprise’s existing project portfolio before drawing their own conclusion from an NPV analysis. 


Table 4-15 Production and financial outcomes from the different irrigated forage and beef production options for a 
representative property in the Southern Gulf catchments 

Details for LOW, MED and HIGH beef prices are in the text above. Descriptions of the six management options are in 
the companion technical report on agricultural viability and socio-economics (Webster et al., 2024). AE = adult 
equivalent; EBITDA = earnings before interest, taxes, depreciation and amortisation. Cattle are sold twice per year for 
all options. Cattle are sold in May for all options. Cattle are sold in September for the two base enterprises and for 
lablab stand and graze. Cattle are sold in October for forage sorghum stand and graze and the two hay options. 



BASE 
ENTERPRISE 

BASE 
ENTERPRISE 
PLUS HAY 

FORAGE 
SORGHUM 
– STAND 
AND GRAZE 

FORAGE 
SORGHUM 
– HAY 

LABLAB – 
STAND AND 
GRAZE 

RHODES 
GRASS – 
HAY 



Forage/hay 

None 

Bought 
hay 

Forage 
sorghum 

Forage 
sorghum 

Lablab 

Rhodes 
grass 



Maximum number of breeders 

1580 

1600 

1705 

1800 

1730 

1800 



Mean of herd size (AE) across calendar year 

1841 

1867 

2107 

2182 

2138 

2188 



Pasture utilisation (%) 

18.1 

18.2 

17.9 

18.2 

18.1 

18.0 



Weaning rate (%) 

55.5 

55.4 

55.9 

57.6 

58.4 

58.9 



Mortality rate (%) 

7.0 

7.0 

6.7 

6.3 

6.3 

6.4 



Percentage of ‘one year old castrate males’ 
(i.e. 7 to 11 months or 8 to 12 months old) 
sold in September or October 

0.0 

0.0 

0.5 

77.5 

57.9 

77.9 



Percentage of ‘one and a half year old 
castrate males’ (i.e. 15 to 19 months old) 
sold in May 

48.3 

60.5 

73.2 

17.8 

25.2 

17.8 



Percentage of ‘two year old castrate males’ 
(i.e. 19 to 23 months or 20 to 24 months 
old) sold in September or October 

11.2 

11.0 

25.0 

4.7 

16.9 

4.2 



Percentage of ‘two and a half year old 
castrate males’ (i.e. 27 to 31 months old) 
sold in May 

40.5 

28.6 

1.3 

0.0 

0.0 

0.0 



Liveweight sold per year (kg) 

212,840 

220,123 

264,395 

303,699 

290,798 

306,171 



Gross margin ($/AE) (LOW beef price) 

91 

78 

-64

103 

40 

129 



Profit (EBITDA) ($) (LOW beef price) 

–96,612 

–119,279 

–398,807

-40,193 

–178,627

17,028 



Gross margin ($/AE) (MED beef price) 

163 

152 

15 

168 

123 

194 



Profit (EBITDA) ($) (MED beef price) 

35,348 

19,399 

–232,238

102,546 

–1,240

160,929 



Gross margin ($/AE) (HIGH beef price) 

236 

226 

94 

232 

205 

260 



Profit (EBITDA) ($) (HIGH beef price) 

169,437 

158,076 

–65,670

242,247 

173,239 

304,829 





A significant proportion of the animal production increases due to the irrigated forage options 
came from the increased number of breeders that could be carried, and the decreased number of 
young animals being carried over an additional wet season in order to achieve sale weight, while 
still keeping the utilisation rate of native pastures close to 18% (Table 4-15). The two irrigated hay 
options allowed the highest number of breeders to be carried (1800) compared with 1580 and 
1600 for the two base enterprises. This flowed through to the total number of AE carried being 
about 17% to 19% higher than the two base enterprises averaged across all years. The total 
liveweight sold each year was about 38% to 44% higher, using the same comparison of options 






due to the higher liveweight gains from the feeding options combined with the higher AE. The 
irrigated options increased the herd’s weaning rate by 0.4% to 3.4% compared to the base 
enterprise without weaner feeding. Even an increase of several per cent is known to have lifetime 
benefits throughout a herd. 
The most obvious biophysical impact of the various feeding strategies was the increase in 
liveweight compared to that of the base enterprise. This allowed a greater proportion of the 
animals to be sold earlier. For example, for the two hay options, more than 77% of the ‘one-year-
old castrate males’ (8–12 months old) were sold in October at a minimum weight of 280 kg, while 
no animals from the same cohort under the two base enterprise options met the minimum weight 
at that time (Table 4-15). These latter animals were retained for an additional wet season, with 
48.3% (base enterprise) or 60.3% (base enterprise plus hay) being sold in the following May as 
‘one-and-a-half-year olds’ (15 to 19 months old). Keeping the utilisation rate at 18.0% meant that 
carrying these animals for the extra period lowered the number of breeders that could be carried, 
and the overall stocking rate (AE). 
In summary, three patterns of growth to reach sale weight (280 kg) occurred: 


•For the two base enterprises, no animals reached sale weight in September as ‘one-year olds’. By 
the following May 48.3% (base enterprise) or 60.5% (base enterprise plus hay) had reached sale 
weight. About 11% were sold in the next September as ‘two-year olds’. The remaining 40.5%
(base enterprise) or 28.6% (base enterprise plus hay) were then sold in the following May as‘two-and-a-half-year olds’.
•By contrast, the majority of animals in the forage sorghum hay, lablab stand and graze, and 
Rhodes grass hay options were sold as ‘one-year olds’ in October. The majority of the rest(17.8%, 25.2% and 17.8%, respectively) were sold in the following May. The remainder were sold 
in the next October. None of this cohort remained for sale in the following May as ‘two-and-a-
half-year olds’.
•The forage sorghum graze option sat between these two extremes. Very few were sold as ‘one- 
year olds’ in October, most were sold as ‘one-and-a-half-year olds’ in the following May with 
almost all of the remainder sold in the following September. Only 1.3% remained to be sold as 
‘two-and-a-half-year olds’ in the following May.


While there are advantages to some form of irrigated forage or hay production, the introduction 
of irrigation to an existing cattle enterprise is not for the faint-hearted. The options here range 
from an area that would require 1.6 pivots of 40 ha each to an area that would require more than 
five 40 ha pivots. A water allocation of about 1.1 to 2.1 GL would be required to provide sufficient 
irrigation water. The capital cost of development would range between $975,000 for 65 ha of 
Rhodes grass hay, at a development cost of $15,000/ha, to $5,125,000 for 205 ha of forage 
sorghum stand and graze at a development cost of $25,000/ha. In addition, the grazing enterprise 
would need to develop the expertise and knowledge required to run a successful irrigation 
enterprise of that scale, which is quite a different enterprise to one of grazing only. This is a 
constraint recognised by graziers elsewhere in northern Australia (McKellar et al., 2015) and 
almost certainly contributes to the lack of uptake of irrigation in the Southern Gulf catchments. 


4.4 Crop synopses 

4.4.1 Introduction 

The estimates for land suitability in these synopses represent the total areas of the catchments 
unconstrained by factors such as water availability, landscape complexity, land tenure, 
environmental and other legislation and regulations, and a range of biophysical risks such as 
cyclones, flooding and secondary salinisation. These are addressed elsewhere by the Assessment. 
The land suitability maps are designed to be used predominantly at the regional scale. Farm-scale 
planning would require finer-scale, more localised assessment. 

4.4.2 Cereal crops 

Cereal production is well established in Australia. The area of land devoted to producing grass 
grains (e.g. wheat, barley (Hordeum vulgare), grain sorghum, maize, oats (Avena sativa), triticale 
(× Triticosecale)) each year has stayed relatively consistent at about 20 million ha over the decade 
from 2012–13 to 2021–22, yielding over 55 Mt with a value of $19 billion in 2021–22 (ABARES, 
2022). Production of cereals greatly exceeds domestic demand, and in 2021–22 the majority (82% 
by value) was exported (ABARES, 2022). Significant export markets exist for wheat, barley and 
grain sorghum, with combined exports valued at $15 billion in 2021–22. There are additional niche 
export markets for grains such as maize and oats. 

Among the cereals, sorghum (grain) is promising for the Southern Gulf catchments. Sorghum is 
grown over the summer period, coinciding with the Southern Gulf catchments wet season. 
Sorghum can be grown opportunistically using rainfed production, although the years in which this 
could be successfully done will be limited. Cereal crop production is higher and more consistent 
when irrigation is used. 

From a land suitability perspective, cereal crops are included in Crop Group 7 (Table 4-2; Figure 
4-10). Cracking clay soils (Vertosols) make up 23% of the catchments; they are principally found onfloodplains and alluvial plains of the Armraynald Plain and Barkly Tableland physiographic units.
Flooding, access and trafficability in the wet season are common constraints across the lowerparts of the Armraynald Plain and crop tolerance to poor soil drainage conditions restricts wet-
season cropping in these areas. Effective rooting depth is deep to very deep (1.2 to 1.5 m) and theclay texture means the soils have a very high (>220 mm) soil AWC. Much of this area is suitable(with moderate or minor limitations) for spray irrigation in the dry season, but inadequatedrainage in the wet season substantially reduces the area suitable for wet-season spray irrigation.
Sandy soils have formed on the Doomadgee Plain (marked S1 and S4 on Figure 2-5) and the GulfFall (marked S3 on Figure 2-5). In total, the red, brown, yellow and grey sandy soils make up 10%
of the area. Friable non-cracking clay or clay loam soils found along the middle reaches of theLeichhardt River make up only about 3% of the area but have potential for agriculture, as do theloamy soils (less than 3% of the area) on the Nicholson River, the Doomadgee and Cloncurry plainsand other isolated areas. Shallow and/or rocky soils make up 56% of the catchments and areunsuitable by definition.

Assuming unconstrained development, approximately 4.7 million ha of the Southern Gulf 
catchments is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better 


(Class 2 or Class 1) for irrigated cereal cropping (Crop Group 7; Table 4-2) using spray irrigation in 
the dry season. For spray irrigation in the wet season, nearly 3.1 million ha is suitable with 
moderate limitations (Class 3) or better. Land considered suitable with moderate limitations for 
furrow irrigation is limited to about 1.8 million ha in the dry season and about 780,000 ha in the 
wet season, due to inadequate soil drainage in clay soils (and/or because gilgais are too deep) and 
because the loamy and sandy soils are too permeable. There is potential for rainfed cereal 
production in the wet season over an area of about 360,000 ha. From a land suitability 
perspective, Crop Group- 7 contains cereal crops and cotton; the latter is considered under 
industrial (cotton) in these crop synopses (Section 4.4.6). 

The ‘winter cereals’ such as wheat and barley are not well adapted to the climate of the Southern 
Gulf catchments. 

To grow cereal crops, farmers will require access to tillage, fertilising, planting, spraying and 
harvesting equipment. Harvesting is often a contract operation, and in larger growing regions 
other activities can also be performed under contract. Because of the low relative value of cereals, 
good returns are made through production at a large scale. This requires machinery to be large so 
that operations can be completed in a timely way. Table 4-16 provides summary information 
relevant to the cultivation of cereals, using sorghum (grain) (Figure 4-11) as an example. The 
companion technical report on agricultural viability and socio-economics (Webster et al., 2024) 
provides greater detail for a wider range of crops. 

 

Figure 4-10 Modelled land suitability for Crop Group 7 (e.g. sorghum (grain) or maize) using furrow irrigation in the 
(a) wet season and (b) dry season 

These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The 
methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital 
soil mapping and land suitability (Thomas et al., 2024). 

Suitability map for crop synopses
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\4_S_Gulf\1_GIS\1_Map_Docs\1_Export\CR-S-Ch4-501_Suit_SorgGrain_MaizeGrain_v2.png
For more information on this figure please contact CSIRO on enquiries@csiro.au



Table 4-16 Summary information relevant to the cultivation of cereals, using sorghum (grain) as an example 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au 






Figure 4-11 Sorghum (grain) 

Photo: CSIRO 

4.4.3 Pulse crops (food legume) 

Pulse production is well established in Australia. The area of land devoted to production of pulses 
(mainly chickpea, lupin (Lupinus spp.) and field pea (Pisum sativum)) each year has varied from 1.1 
to 2.0 million ha over the decade from 2012–13 to 2021–22, yielding over 3.8 Mt with a value of 
$2.5 billion in 2021–22 (ABARES, 2022). The vast majority of pulses in 2021–22 (93% by value) 
were exported (ABARES, 2022). Pulses produced in the Southern Gulf catchments would most 
likely be exported, although there is presently no cleaning or bulk handling facility nearby; 
however, established export ports are located at Townsville and Karumba. 

Many pulse crops have a relatively short growing season, meaning they are well suited to 
opportunistic rainfed production, as well as irrigated production either as a single crop or in 
rotation with cereals or other non-legume crops. Not all pulse crops are likely to be suited to the 
Southern Gulf catchments. Those that are ‘tender’, such as field peas and beans, may not be well 
suited to the highly desiccating environment and periodically high temperatures. Direct field 
experimentation in the catchment is required to confirm this for these and other species. In the 
Southern Gulf catchments, mungbean and chickpea are likely to be well suited. 

From a land suitability perspective, pulse crops are included in Crop Group 10 (Table 4-2; Figure 
4-12). Cracking clay soils (Vertosols) make up 23% of the catchment; they are principally found onfloodplains and alluvial plains of the Armraynald Plain and Barkly Tableland physiographic units.
Flooding, access and trafficability in the wet season are common constraints across the lowerparts of the Armraynald Plain and crop tolerance to poor soil drainage conditions restricts wet-


season cropping in these areas. Effective rooting depth is deep to very deep (1.2 to 1.5 m) and the 
clay texture means the soils have a very high (>220 mm) soil AWC. Much of this area is suitable 
(with moderate or minor limitations) for spray irrigation in the dry season, but inadequate 
drainage in the wet season substantially reduces the area suitable for wet-season spray irrigation. 
Sandy soils have formed on the Doomadgee Plain (marked S1 and S4 on Figure 2-5) and the Gulf 
Fall (marked S3 on Figure 2-5). In total, the red, brown, yellow and grey sandy soils make up 10% 
of the area. Friable non-cracking clay or clay loam soils found along the middle reaches of the 
Leichhardt River make up only about 3% of the area but have potential for agriculture, as do the 
loamy soils (less than 3% of the area) on the Nicholson River, the Doomadgee and Cloncurry plains 
and other isolated areas. Shallow and/or rocky soils make up 56% of the catchments and are 
unsuitable by definition. 

Assuming unconstrained development, approximately 4.7 million ha of the Southern Gulf 
catchments is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better 
(Class 2 or Class 1) for irrigated pulse cropping (Crop Group 10; Table 4-2) using spray irrigation in 
the dry season. Nearly 1.7 million ha of land is considered suitable with moderate limitations for 
furrow irrigation in the dry season, due to inadequate soil drainage in clay soils (and/or because 
gilgais are too deep) and because the loamy soils are too permeable. There is potential for rainfed 
pulse production in the wet season over an area of about 360,000 ha. From a land suitability 
perspective, Crop Group 10 includes the pulse crops mungbean and chickpea, while soybean is 
considered under oilseeds in these crop synopses (Section 4.4.4). 

Pulses are often advantageous in rotation with other crops because they provide a disease break 
and, being legumes, can provide nitrogen for subsequent crops. Even where this is not the case, 
their ability to meet their own nitrogen needs can be beneficial in reducing costs of fertiliser and 
associated freight. Pulses such as mungbean and chickpea can also be of high value (historical 
prices have reached >$1000/t), so the freight costs as a percentage of the value of the crop are 
lower than for cereal grains. 

To grow pulse crops, farmers will require access to tillage, fertilising, planting, spraying and 
harvesting equipment. Harvesting is generally a contract operation, and in larger growing regions 
other activities can also be performed under contract. The equipment required for pulse crops is 
the same as is required for cereal crops, so farmers intending on a pulse and cereal rotation would 
not need to purchase extra equipment. 

Table 4-17 provides summary information relevant to the cultivation of many pulses using 
mungbean (Figure 4-13) as an example. The companion technical report on agricultural viability 
and socio-economics (Webster et al., 2024) provides greater detail for a wider range of crops. 




Suitability map for crop synopses
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\4_S_Gulf\1_GIS\1_Map_Docs\1_Export\CR-S-Ch4-502_Suit_Mung_Mung_v1.png
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 4-12 Modelled land suitability for mungbean (Crop Group 10) in the dry season using (a) furrow irrigation and 
(b)spray irrigation

These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. Themethods used to derive the reliability data in the inset maps are outlined in the companion technical report on digitalsoil mapping and land suitability (Thomas et al., 2024).




Figure 4-13 Mungbean 

Photo: CSIRO 


Table 4-17 Summary information relevant to the cultivation of pulses, using mungbean as an example 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
4.4.4 Oilseed crops 

The area of land in Australia devoted to production of oilseeds (predominantly canola, Brassica 
napus) each year has varied between 2.1 and 3.4 million ha over the decade from 2012–13 to 
2021–22, yielding over 8.4 Mt with a value of $6.1 billion in 2021–22 (ABARES, 2022). The majority 
of oilseed produced in 2021–22 (98% by value) was exported (ABARES, 2022). Canola dominates 
Australian oilseed production, accounting for 98% of the gross value of oilseeds in 2021–22. 
Soybean, sunflower (Helianthus annuus) and other oilseeds (including peanuts) each accounted 
for less than 1%. 


Soybean, canola and sunflower are oilseed crops used to produce vegetable oils and biodiesel, and 
high-protein meals for intensive animal production. Soybean is also used in processed foods such 
as tofu. It can provide both green manure and soil benefits in crop rotations, with symbiotic 
nitrogen fixation adding to soil fertility and sustainability in an overall cropping system. Soybean is 
used commonly as a rotation crop with sugarcane in northern Queensland, although often as a 
green manure crop. Summer oilseed crops such as soybean and sunflower are more suited to 
tropical environments than are winter-grown oilseed crops such as canola. Cottonseed, a by-
product of cotton farming separated from the lint during ginning, is also classified as an oilseed. 
Cottonseed is used for animal feed and oil extraction. 

Soybean is sensitive to photoperiod (day length) and requires careful consideration in selection of 
the appropriate variety for a particular sowing window. 

From a land suitability perspective, soybean is included in Crop Group 10 (Table 4-2; Figure 4-14). 
Cracking clay soils (Vertosols) make up 23% of the catchment; they are principally found on 
floodplains and alluvial plains of the Armraynald Plain and Barkly Tableland physiographic units. 
Flooding, access and trafficability in the wet season are common constraints across the lower 
parts of the Armraynald Plain and crop tolerance to poor soil drainage conditions restricts wet-
season cropping in these areas. Effective rooting depth is deep to very deep (1.2 to 1.5 m) and the 
clay texture means the soils have a very high (>220 mm) soil AWC. Much of this area is suitable 
(with moderate or minor limitations) for spray irrigation in the dry season, but inadequate 
drainage in the wet season substantially reduces the area suitable for wet-season spray irrigation. 
Sandy soils have formed on the Doomadgee Plain (marked S1 and S4 on Figure 2-5) and the Gulf 
Fall (marked S3 on Figure 2-5). In total, the red, brown, yellow and grey sandy soils make up 10% 
of the area. Friable non-cracking clay or clay loam soils found along the middle reaches of the 
Leichhardt River make up only about 3% of the area but have potential for agriculture, as do the 
loamy soils (less than 3% of the area) on the Nicholson River, the Doomadgee and Cloncurry plains 
and other isolated areas. Shallow and/or rocky soils make up 56% of the catchments and are 
unsuitable by definition. 

Assuming unconstrained development, approximately 4.7 million ha of the Southern Gulf 
catchments is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better 
(Class 2 or Class 1) for irrigated soybean cropping (Crop Group 10; Table 4-2) using spray irrigation 
in the dry season. Nearly 1.7 million ha of land is considered suitable with moderate limitations for 
furrow irrigation in the dry season, due to inadequate soil drainage in clay soils (and/or because 
gilgais are too deep) and because the sandy and loamy soils are too permeable. There is potential 
for rainfed pulse production in the wet season over an area of about 360,000 ha. From a land 
suitability perspective, Crop Group 10 contains the pulse crops mungbean and chickpea, while 
soybean is considered under oilseeds in these crop synopses. 

To grow oilseed crops, farmers will require access to tillage, fertilising, planting, spraying and 
harvesting equipment. Harvesting is generally a contract operation and in larger growing regions 
other activities can also be performed under contract. The equipment required for oilseed crops is 
the same as is required for cereal crops, so farmers intending on an oilseed and cereal rotation 
would not need to purchase oilseed-specific equipment. 

With no oilseed processing facility in the north, soybean and sunflowers would need to be 
transported a significant distance until sufficient scales of production are achieved to justify the 


investment in processing facilities. Given both the modest yield and price, transport costs are likely 
to be a major constraint on profitability unless there is a well-developed supply chain into Asia. 

Table 4-18 provides summary information relevant to the cultivation of oilseed crops using 
soybean (Figure 4-15) as an example. The companion technical report on agricultural viability and 
socio-economics (Webster et al., 2024) provides greater detail for a wider range of crops. 



Suitability map for crop synopses
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\4_S_Gulf\1_GIS\1_Map_Docs\1_Export\CR-S-Ch4-503_Suit_Soy_Soy_v1.png
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 4-14 Modelled land suitability for soybean (Crop Group 10) in the dry season using (a) furrow irrigation and 
(b)spray irrigation

These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. Themethods used to derive the reliability data in the inset maps are outlined in the companion technical report on digitalsoil mapping and land suitability (Thomas et al., 2024).




Figure 4-15 Soybean 

Photo: CSIRO 


Table 4-18 Summary information relevant to the cultivation of oilseed crops, using soybean as an example 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
4.4.5 Root crops, including peanut 

Root crops, including peanut, sweet potato (Ipomoea batatas) and cassava (Manihot esculenta), 
are potentially well suited to the lighter soils across much of the Doomadgee Plain. Root crops 
such as these are not suited to growing on heavier clay soils because they need to be pulled from 
the ground for harvest, and the heavy clay soils, such as cracking clays, are not conducive to 
mechanical pulling. While peanut is technically an oilseed crop, it has been included in the root 


crop category due to its similar land suitability and management requirements (i.e. the need for it 
to be pulled from the ground as part of the harvest operation). 

The most widely grown root crop in Australia, peanut is a legume crop that requires little or no 
nitrogen fertiliser and is very well suited to growing in rotation with cereal crops, as it is frequently 
able to fix atmospheric nitrogen in the soil for following crops. The Australian peanut industry 
currently produces approximately 15,000 to 20,000 t/year from around 11,000 ha, which is too 
small an industry to be reported separately in Australian Bureau of Agricultural and Resource 
Economics and Sciences statistics (ABARES, 2022). The Australian peanut industry is concentrated 
in Queensland. In northern Australia, a production area is present on the Atherton Tablelands, and 
peanuts could likely be grown in the Southern Gulf catchments. The Peanut Company of Australia 
established a peanut-growing operation at Katherine in 2007 and examined the potential of both 
wet- and dry-season peanut crops, mostly in rotation with maize. Due to changing priorities within 
the company, coupled with some agronomic challenges (Jakku et al., 2016), the company sold its 
land holdings in Katherine in 2012 (and Bega bought the rest of the company in 2018). For peanuts 
to be successful, considerable planning would be needed in determining the best season for 
production and practical options for crop rotations. The nearest peanut-processing facilities to the 
Southern Gulf catchments are at Tolga on the Atherton Tablelands and Kingaroy in southern 
Queensland. 

From a land suitability perspective, peanut is included in Crop Group 6 (Table 4-2; Figure 4-16). 
Cracking clay soils (Vertosols) make up 23% of the catchment; they are principally found on 
floodplains and alluvial plains of the Armraynald Plain and Barkly Tableland physiographic units. 
Flooding, access and trafficability in the wet season are common constraints across the lower 
parts of the Armraynald Plain and crop tolerance to poor soil drainage conditions restricts wet-
season cropping in these areas. Effective rooting depth is deep to very deep (1.2 to 1.5 m) and the 
clay texture means the soils have a very high (>220 mm) soil AWC. Much of this area is suitable 
(with moderate or minor limitations) for spray irrigation in the dry season, but inadequate 
drainage in the wet season substantially reduces the area suitable for wet-season spray irrigation. 
Sandy soils have formed on the Doomadgee Plain (marked S1 and S4 on Figure 2-5) and the Gulf 
Fall (marked S3 on Figure 2-5). In total, the red, brown, yellow and grey sandy soils make up 10% 
of the area. Friable non-cracking clay or clay loam soils found along the middle reaches of the 
Leichhardt River make up only about 3% of the area but have potential for agriculture, as do the 
loamy soils (less than 3% of the area) on the Nicholson River, the Doomadgee and Cloncurry plains 
and other isolated areas. Shallow and/or rocky soils make up 56% of the catchments and are 
unsuitable by definition. 

Assuming unconstrained development, approximately 3.7 million ha of the Southern Gulf 
catchments is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better 
(Class 2 or Class 1) for irrigated root crops (Crop Group 6; Table 4-2) using spray irrigation in the 
dry season. For spray irrigation in the wet season, about 2.0 million ha is suitable with moderate 
limitations (Class 3) or better. Furrow irrigation was not considered in the land suitability analysis 
as root crops prefer lighter-textured soils too permeable for furrow irrigation. 

To grow root crops, farmers will require access to tillage, fertilising, planting, spraying and 
harvesting equipment. The harvesting operation requires specialised equipment to ‘pull’ the crop 


from the ground, and then to pick it up after a drying period. Peanuts are usually dried soon after 
harvest, in industrial driers. 

Table 4-19 provides summary information relevant to the cultivation of root crops using peanut 
(Figure 4-17) as an example. The companion technical report on agricultural viability and socio-
economics (Webster et al., 2024) provides greater detail for a wider range of crops. 



Suitability map for crop synopses
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\4_S_Gulf\1_GIS\1_Map_Docs\1_Export\CR-S-Ch4-504_Suit_Peanut_Peanut_v2.png
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 4-16 Modelled land suitability for peanut (Crop Group 6) using spray irrigation in the (a) wet season and (b) 
dry season 

These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The 
methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital 
soil mapping and land suitability (Thomas et al., 2024). 




Figure 4-17 Peanut 

Photo: Shutterstock 


Table 4-19 Summary information relevant to the cultivation of root crops, using peanut as an example 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au





4.4.6 Industrial (cotton) 
Rainfed and irrigated cotton production are well established in Australia. The area of land devoted 
to cotton production varies widely from year to year, largely in response to availability of water. It 
varied from 70,000 to 600,000 ha between 2012–13 and 2021–22; a mean of 400,000 ha/year has 
been grown over the decade (ABARES, 2022). Likewise, the gross value of cotton lint production 
varied greatly between 2012–13 and 2021–22, from $0.3 billion in 2019–20 to $5.2 billion in 
2021–22. Genetically modified cotton varieties were introduced in 1996 and now account for 
almost all cotton produced in Australia (over 99%). Australia was the fourth largest exporter of 
cotton in 2022, behind the United States, India and Brazil. Cottonseed is a by-product of cotton 
processing and is a valuable cattle feed. Mean lint production in Australia in 2015–16 was 8.8 
bales/ha (ABARES, 2022).
Commercial cotton has a long but discontinuous history of production in northern Australia, 
including in Broome, the Fitzroy River and the Ord River Irrigation Area in WA; in Katherine and 
Douglas–Daly in the NT; and near Richmond and Bowen in northern Queensland. An extensive 
study undertaken by the Australian Cotton Cooperative Research Centre in 2001 (Yeates, 2001) 
noted that past ventures suffered from: 

•a lack of capital investment
•too rapid a movement to commercial production
•a failure to adopt a systems approach to development
•climate variability.


Mistakes in pest control were also a major issue in early projects. Since the introduction of 
genetically modified cotton in 1996, yields and incomes from cotton crops have increased in most 
regions of Australia. The key benefits of genetically modified cotton over conventional cotton are 
savings in insecticide and herbicide use, and improved tillage management. In addition, farmers 
can now forward-sell their crop as part of a risk management strategy. Growers of genetically 
modified cotton are required to comply with the approved practices for growing the genetically 
modified varieties, including preventative resistance management. 

Research and commercial test farming have demonstrated that the biophysical challenges are 
manageable if the growing of cotton is tailored to the climate and biotic conditions of northern 
Australia (Yeates et al., 2013). In recent years, irrigated cotton crops achieving more than 
10 bales/ha have been grown successfully in the Burdekin irrigation region and experimentally in 
the Gilbert catchment of northern Queensland. Expansion of cotton through private investment is 
occurring in the catchments of the Leichhardt, Flinders and upper Mitchell rivers, Queensland. 
Cotton will be processed near Katherine, NT, at a gin commissioned in 2024. New genetically 
modified cotton using CSIRO varieties that are both pest- and herbicide-resistant are an important 
component of these northern cotton production systems. 

Climate constraints will continue to limit production potential of northern cotton crops when 
compared to cotton grown in more favourable climate regions of NSW and Queensland. On the 
other hand, the low risk of rainfall occurring during late crop development favours production in 
northern Australia, as it minimises the likelihood of late-season rainfall, which can downgrade 
fibre quality and price. Demand for Australian cotton exhibiting long and fine attributes is 


expected to increase by 10% to 20% during the next decade and presents local producers with an 
opportunity to target production of high-quality fibre. 

From a land suitability perspective, cotton is included in Crop Group 7 (Table 4-2; Figure 4-18). 
Cracking clay soils (Vertosols) make up 23% of the catchment; they are principally found on 
floodplains and alluvial plains of the Armraynald Plain and Barkly Tableland physiographic units. 
Flooding, access and trafficability in the wet season are common constraints across the lower 
parts of the Armraynald Plain and crop tolerance to poor soil drainage conditions restricts wet-
season cropping in these areas. Effective rooting depth is deep to very deep (1.2 to 1.5 m) and the 
clay texture means the soils have a very high (>220 mm) soil AWC. Much of this area is suitable 
(with moderate or minor limitations) for spray irrigation in the dry season, but inadequate 
drainage in the wet season substantially reduces the area suitable for wet-season spray irrigation. 
Sandy soils have formed on the Doomadgee Plain (marked S1 and S4 on Figure 2-5) and the Gulf 
Fall (marked S3 on Figure 2-5). In total, the red, brown, yellow and grey sandy soils make up 10% 
of the area. Friable non-cracking clay or clay loam soils found along the middle reaches of the 
Leichhardt River make up only about 3% of the area but have potential for agriculture, as do the 
loamy soils (less than 3% of the area) on the Nicholson River, the Doomadgee and Cloncurry plains 
and other isolated areas. Shallow and/or rocky soils make up 56% of the catchments and are 
unsuitable by definition. 

Assuming unconstrained development, approximately 4.7 million ha of the Southern Gulf 
catchments is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better 
(Class 2 or Class 1) for irrigated cotton (Crop Group 7; Table 4-2) using spray irrigation in the dry 
season. For spray irrigation in the wet season, nearly 3.1 million ha is suitable with moderate 
limitations (Class 3) or better. Land considered suitable with moderate limitations for furrow 
irrigation is limited to about 1.8 million ha in the dry season and about 780,000 ha in the wet 
season, due to inadequate soil drainage in clay soils (and/or because gilgais are too deep) and 
because the loamy soils are too permeable. There is potential for rainfed cotton production in the 
wet season over an area of about 360,000 ha. From a land suitability perspective, Crop Group 7 
contains both cotton and cereal crops; the latter are considered elsewhere in these crop synopses 
(Section 4.4.2). 

In addition to a normal row planter and spray rig equipment used in cereal production, cotton 
requires access to suitable picking and module or baling equipment, as well as transport to 
processing facilities. Decisions on initial development costs and scale of establishing cotton 
production in the catchments would need to consider the need to source external contractors; this 
could provide an opportunity to develop local contract services to support a growing industry. 

Cotton production is also highly dependent on access to processing plants (cotton gins). The 
closest processing facility for cotton grown in the Southern Gulf catchments is Emerald, 
Queensland. The first cotton gin in northern Australia will be processing in 2024 and is near 
Katherine in the NT. 

Niche industrial crops, such as guar (Cyamopsis tetragonoloba) and chia (Salvia hispanica), may be 
feasible for the Southern Gulf catchments, but verified agronomic and market data on these crops 
are limited. Past research on guar has been conducted in the NT, and trials are currently 
underway. Hemp is a photoperiod-sensitive summer annual with a growing season between 70 
and 120 days depending on variety and temperature. Hemp is well suited to growing in rotation 


with legumes, as hemp can use the nitrogen fixed by the legume crop. Industrial hemp can be 
harvested for grain with modifications to conventional headers, otherwise all other farming 
machinery for ground preparation, fertilising and spraying can be used. There are legislative 
restrictions to growing hemp in Australia, and jurisdictions including the NT are implementing 
industrial hemp legislation to license growing of industrial hemp to facilitate development of the 
industry. The companion technical report on agricultural viability and socio-economics (Webster et 
al., 2024) provides greater detail for a wider range of industrial crops. 

Table 4-20 describes some key considerations relating to cotton production (Figure 4-19). 

 

Suitability map for crop synopses
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\4_S_Gulf\1_GIS\1_Map_Docs\1_Export\CR-S-Ch4-507_Suit_Cotton_Cotton_v2.png
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 4-18 Modelled land suitability for cotton (Crop Group 7) using furrow irrigation in the (a) wet season and (b) 
dry season 

These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The 
methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital 
soil mapping and land suitability (Thomas et al., 2024). 

 


Figure 4-19 Cotton 

Photo: CSIRO 


Table 4-20 Summary information relevant to the cultivation of cotton 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au 



4.4.7 Forages 

Forage, hay and silage are crops that are grown for consumption by animals. Forage is consumed 
in the paddock in which it is grown and is often referred to as ‘stand and graze’. Hay is cut, dried, 
baled and stored before being fed to animals, usually in yards for weaning or when animals are 
being held for sale. Silage production resembles that for hay, but harvested forage is stored wet in 
wrapped bales or covered ground pits, where anaerobic fermentation occurs, to preserve the 
feed’s nutritional value. Silage is often used as a production feed to grow animals to meet the 
specifications of premium markets. 

Rainfed and irrigated production of forage crops is well established throughout Australia, with 
over 20,000 producers, most of whom are not specialist producers. Approximately 85% of forage 
production is consumed domestically, with the rest primarily used on live export ships, often in a 
pelleted form. The largest consumers are the horse, dairy and beef feedlot industries. Forage 
crops are also widely used in horticulture for mulches and for erosion control. There is a significant 
fodder trade in support of the northern beef industry, with further room for expansion since 
fodder costs constitute less than 5% of beef production costs (Gleeson et al., 2012). 

The Southern Gulf catchments are suited to rainfed or irrigated production of forage, hay and 
silage. Rainfed and irrigated hay production currently occurs in the north-west Queensland region. 

Non-leguminous forage, hay and silage 

Forage crops, both annual and perennial, include sorghum, Rhodes grass, maize and Jarra grass 
(Digitaria milanjiana ‘Jarra’), with specific forage cultivars. If irrigated, these grass forages require 
considerable amounts of water and nitrogen as they can be high yielding (20 to 40 t dry matter per 
ha per year). Given the rapid growth of grass forages, crude protein levels can decrease quickly to 
less than 7%, reducing their value as a feed. To maintain high nutritive value (10% to 15% crude 
protein), high levels of nitrogen fertiliser need to be applied, and in the case of hay the crop needs 
to be cut every 45 to 60 days. 

After cutting, the crop grows back without the need for resowing. The rapid growth of forage 
during the wet season can make it challenging to match animal numbers to forage growth so that 
it is kept leafy and nutritious, and does not become rank and of low quality. Producing rainfed hay 
from perennials gives producers the option of irrigating when required or, if water becomes 
limiting, allowing the pasture to remain dormant before water again becomes available. Silage can 
be made from a number of crops, such as grasses, maize and forage sorghum. 

From a land suitability perspective, Rhodes grass is included in Crop Group 14 (Table 4-2; Figure 
4-20). Cracking clay soils (Vertosols) make up 23% of the catchment; they are principally found on 
floodplains and alluvial plains of the Armraynald Plain and Barkly Tableland physiographic units. 
Flooding, access and trafficability in the wet season are common constraints across the lower 
parts of the Armraynald Plain and crop tolerance to poor soil drainage conditions restricts wet-
season cropping in these areas. Effective rooting depth is deep to very deep (1.2 to 1.5 m) and the 
clay texture means the soils have a very high (>220 mm) soil AWC. Much of this area is suitable 
(with moderate or minor limitations) for spray irrigation in the dry season, but inadequate 
drainage in the wet season substantially reduces the area suitable for wet-season spray irrigation. 
Sandy soils have formed on the Doomadgee Plain (marked S1 and S4 on Figure 2-5) and the Gulf 
Fall (marked S3 on Figure 2-5). In total, the red, brown, yellow and grey sandy soils make up 10% 


of the area. Friable non-cracking clay or clay loam soils found along the middle reaches of the 
Leichhardt River make up only about 3% of the area but have potential for agriculture, as do the 
loamy soils (less than 3% of the area) on the Nicholson River, the Doomadgee and Cloncurry plains 
and other isolated areas. Shallow and/or rocky soils make up 56% of the catchments and are 
unsuitable by definition. 

Assuming unconstrained development, approximately 4.7 million ha of the Southern Gulf 
catchments is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better 
(Class 2 or Class 1) for irrigated cropping of annual forages (Crop Group 12; Table 4-2) using spray 
irrigation in the dry season. For spray irrigation in the wet season, nearly 3.1 million ha is suitable 
with moderate limitations (Class 3) or better. Land considered suitable with moderate limitations 
for furrow irrigation is limited to about 1.8 million ha in the dry season and about 780,000 ha in 
the wet season, due to inadequate soil drainage in clay soils (and/or because gilgais are too deep) 
and because the loamy soils are too permeable. There is potential for rainfed production of annual 
forages in the wet season over an area of about 620,000 ha. For perennial Rhodes grass, about 
5.1 million ha is suitable with moderate or minor limitations under spray irrigation and about 
1.8 million ha under furrow irrigation. 

Apart from irrigation infrastructure, the equipment needed for forage production is machinery for 
planting and fertilising. Spraying equipment is also desirable but not necessary. Cutting crops for 
hay or silage requires more-specialised harvesting, cutting, baling and storage equipment. 

Table 4-21 describes Rhodes grass production (Figure 4-21) for hay over 1 year of a 6-year cycle. 
Information similar to that in Table 4-21 for grazed forage crops is presented in the companion 
technical report on agricultural viability and socio-economics (Webster et al., 2024). 

 

Suitability map for crop synopses
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\4_S_Gulf\1_GIS\1_Map_Docs\1_Export\CR-S-Ch4-505_Suit_Rhodes_Rhodes_v1.png
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 4-20 Modelled land suitability for Rhodes grass (Crop Group 14) using (a) spray irrigation and (b) furrow 
irrigation 

These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The 
methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital 
soil mapping and land suitability (Thomas et al., 2024). 


 


Figure 4-21 Rhodes grass 

Photo: CSIRO 

Table 4-21 Rhodes grass production for hay over 1 year of a 6-year cycle 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
Forage legume 

The use of forage legumes is similar to that of forage grasses. They are generally grazed by animals 
but can also be cut for silage or hay. Some forage legumes are well suited to the Southern Gulf 
catchments and would be considered among the more promising opportunities for irrigated 
agriculture (Figure 4-22). 

Forage legumes are desirable because of their high protein content and their ability to fix 
atmospheric nitrogen in the soil. The nitrogen fixed during a forage legume phase is often in 
excess of requirements and remains in the soil as additional nitrogen available to subsequent 
crops. Forage legumes are being used by the northern cattle industry, and farmers primarily 
engaged in extensive cattle production could use irrigated forage legumes to increase the capacity 
of their enterprise, turning out more cattle from the same area. Cavalcade (Centrosema 
pascuorum ‘Cavalcade’) and lablab are currently grown in northern Australia and would be well 
suited to the Southern Gulf catchments. Hay crops are commonly used as a component of forage 
pellets that are used to feed live export cattle in holding yards and on boats during transport. 

From a land suitability perspective, forage legumes such as Cavalcade and lablab are included in 
Crop Group 13 (Table 4-2; Figure 4-22). Cracking clay soils (Vertosols) make up 23% of the 
catchment; they are principally found on floodplains and alluvial plains of the Armraynald Plain 
and Barkly Tableland physiographic units. Flooding, access and trafficability in the wet season are 
common constraints across the lower parts of the Armraynald Plain and crop tolerance to poor soil 
drainage conditions restricts wet-season cropping in these areas. Effective rooting depth is deep to 
very deep (1.2 to 1.5 m) and the clay texture means the soils have a very high (>220 mm) soil 
AWC. Much of this area is suitable (with moderate or minor limitations) for spray irrigation in the 
dry season, but inadequate drainage in the wet season substantially reduces the area suitable for 
wet-season spray irrigation. Sandy soils have formed on the Doomadgee Plain (marked S1 and S4 
on Figure 2-5) and the Gulf Fall (marked S3 on Figure 2-5). In total, the red, brown, yellow and grey 
sandy soils make up 10% of the area. Friable non-cracking clay or clay loam soils found along the 
middle reaches of the Leichhardt River make up only about 3% of the area but have potential for 
agriculture, as do the loamy soils (less than 3% of the area) on the Nicholson River, the 


Doomadgee and Cloncurry plains and other isolated areas. Shallow and/or rocky soils make up 
56% of the catchments and are unsuitable by definition. 

Assuming unconstrained development, approximately 4.8 million ha of the Southern Gulf 
catchments is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better 
(Class 2 or Class 1) for irrigated forage legumes (Crop Group 13; Table 4-2) using spray irrigation in 
the dry season. For spray irrigation in the wet season, nearly 2.7 million ha is suitable with 
moderate limitations (Class 3) or better. Land considered suitable with moderate or minor 
limitations for furrow irrigation is limited to about 4.8 million ha in the dry season and about 
580,000 ha in the wet season, due to inadequate soil drainage in clay soils (and/or because gilgais 
are too deep) and because the loamy soils are too permeable. There is potential for rainfed forage 
legume production in the wet season over an area of about 220,000 ha. 

The equipment needed for grazed forage legume production is similar to that for forage grasses: a 
planting method, with fertilising and spraying equipment, is desirable but not essential. Cutting 
crops for hay or silage requires more-specialised harvesting, cutting, baling and storage 
equipment. 

Table 4-22 describes Cavalcade production over a 1-year cycle. The comments could be applied 
equally to lablab production (Figure 4-23). 

 

Suitability map for crop synopses
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\4_S_Gulf\1_GIS\1_Map_Docs\1_Export\CR-S-Ch4-506_Suit_Cavalcade_Cavalcade_v1.png
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 4-22 Modelled land suitability for Cavalcade (Crop Group 13) in the wet season using (a) spray irrigation and 
(b) furrow irrigation 

These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The 
methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital 
soil mapping and land suitability (Thomas et al., 2024). 


Table 4-22 Cavalcade production over a 1-year cycle 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au 



 


Figure 4-23 Lablab 

Photo: CSIRO 

4.4.8 Horticulture 

Intensive horticulture is an important and widespread industry in Australia, occurring in every 
state, particularly close to capital city markets. Horticultural production varied between 2.9 and 
3.3 Mt/year between 2012–13 and 2021–22, of which 65% to 70% was vegetables (ABARES, 2022). 
Unlike broadacre crops, most horticultural production in Australia is consumed domestically. The 
total gross value of horticultural production was $13.2 billion in 2021–22 (up from $9.3 billion in 
2012–13), of which 24% was from exports (ABARES, 2022). Horticulture is also an important 
source of jobs, employing approximately a third of all people working in agriculture. 

Horticultural production is more intensive than broadacre production and has a higher degree of 
risk, such as a short season of supply and highly volatile prices as a result of highly inelastic supply 
and demand. Managing these issues requires a heightened understanding of risks, markets, 
transport and supply chain issues (including associated interactions with other horticultural 
production regions). 

Production is highly seasonal and can involve multiple crops produced on individual farms to 
manage labour resources. The importance of freshness in many horticultural products means 
seasonality of supply is important in the market. Farms in the Southern Gulf catchments have the 
advantage of being able to produce out-of-season supplies to southern markets. However, they 
must also compete with production regions in the NT and northern WA, which are already 
established production areas with associated infrastructure. Southern Gulf catchments may have 


an advantage over these regions in being geographically closer to most of the urban consumer 
centres of south-eastern Australia. 

Horticulture (row crops) 

Horticultural row crops are generally short-lived, annual crops, grown in the ground, such as 
seedless watermelons (Citrullus lanatus), rockmelon and honeydew melon (Cucumis melo), as well 
as sweet corn (Zea mays). Almost all produce is shipped to capital cities where major central 
markets are located. Row crops such as watermelon and rockmelon use staggered plantings over a 
season (e.g. planted every 2 to 3 weeks) to extend the period over which harvested produce is 
sold. This strategy allows better use of labour and better management for risks of price 
fluctuations. Often only a short period of time with very high prices is enough to make melon 
production a profitable enterprise. 

From a land suitability perspective, intensive horticulture row crops such as rockmelon are 
included in Crop Group 3 (Table 4-2). Cracking clay soils (Vertosols) make up 23% of the 
catchment; they are principally found on floodplains and alluvial plains of the Armraynald Plain 
and Barkly Tableland physiographic units. Flooding, access and trafficability in the wet season are 
common constraints across the lower parts of the Armraynald Plain and crop tolerance to poor soil 
drainage conditions restricts wet-season cropping in these areas. Effective rooting depth is deep to 
very deep (1.2 to 1.5 m) and the clay texture means the soils have a very high (>220 mm) soil 
AWC. Much of this area is suitable (with moderate or minor limitations) for spray irrigation in the 
dry season, but inadequate drainage in the wet season substantially reduces the area suitable for 
wet-season spray irrigation. Sandy soils have formed on the Doomadgee Plain (marked S1 and S4 
on Figure 2-5) and the Gulf Fall (marked S3 on Figure 2-5). In total, the red, brown, yellow and grey 
sandy soils make up 10% of the area. Friable non-cracking clay or clay loam soils found along the 
middle reaches of the Leichhardt River make up only about 3% of the area but have potential for 
agriculture, as do the loamy soils (less than 3% of the area) on the Nicholson River, the 
Doomadgee and Cloncurry plains and other isolated areas. Shallow and/or rocky soils make up 
56% of the catchments and are unsuitable by definition. 

A wide range of horticultural row crops are considered in the land suitability analysis (crop groups 
3, 4, 5, 6 and 18; Table 4-2; Figure 4-24). Assuming unconstrained development, between about 
3.4 million ha and 4.9 million ha of the Southern Gulf catchments is considered to be suitable with 
moderate limitations (Class 3; Table 4-1) or better (Class 2 or Class 1) using spray or trickle 
irrigation in the dry season. Land considered suitable with moderate limitations for furrow 
irrigation of sweet corn (Crop Group 18) is limited to about 1.7 million ha in the dry season and 
only 780,000 ha in the wet season, due to inadequate soil drainage in clay soils (and/or because 
gilgais are too deep) and because the loamy soils are too permeable. 

Horticultural row crops are well established throughout the NT, Burdekin and Mareeba–Dimbulah 
Water Supply Scheme region in Queensland. The NT melon industry, consisting of watermelon 
(seedless), rockmelon and honeydew, produces approximately 25% of Australia’s melons. Melon 
production would be well suited to the Southern Gulf catchments, which could compete with NT 
production. 

Horticulture typically requires specialised equipment and a large labour force. Therefore, a system 
for attracting, managing and retaining sufficient staff is also required. Harvesting is often by hand, 


but packing equipment is highly specialised. Irrigation is generally with micro or trickle equipment, 
but overhead spray is also feasible. Leaf fungal diseases need to be carefully managed when using 
spray irrigation. Micro spray equipment has the advantage of being able to deliver fertiliser along 
with irrigation. Table 4-23 describes some key considerations relating to row crop horticulture 
production, with rockmelon (Figure 4-25) as an example. 

 

Suitability map for crop synopses
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\4_S_Gulf\1_GIS\1_Map_Docs\1_Export\CR-S-Ch4-508_Suit_Rockmelon_Onion_v1.png
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 4-24 Modelled land suitability for (a) cucurbits (e.g. rockmelon, Crop Group 3) using trickle irrigation in the 
dry season and (b) root crops such as onion (Crop Group 6) using spray irrigation in the wet season 

These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The 
methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital 
soil mapping and land suitability (Thomas et al., 2024). 

 

Rockmelon
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 4-25 Rockmelon 

Photo: Shutterstock 


Table 4-23 Summary information relevant to row crop horticulture production, with rockmelon as an example 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au 


Horticulture (tree crops) 

Some fruit and tree crops, such as mangoes and citrus (Citrus spp.), are well suited to the climate 
of the Southern Gulf catchments. Other species, such as avocado (Persea americana) and lychee 
(Litchi chinensis), are not likely to be as well adapted to the climate due to high temperatures and 
low humidity. Tree crops are generally not well suited to cracking clays, which make up some of 
the arable soils for irrigated agriculture in the Southern Gulf catchments. Horticultural tree 
production is more feasible on the lighter, well-drained soils in the north-west of the Southern 
Gulf catchments. 

Fruit production shares many of the marketing and risk features of horticultural row crops, such as 
a short season of supply and highly volatile prices as a result of highly inelastic supply and 
demand. Managing these issues requires a heightened understanding of risks, markets, transport 
and supply chain issues. The added disadvantage of fruit tree production is the time lag between 
planting and production, meaning decisions to plant need to be made with a long time frame for 
production and return in mind. Mango production in the NT is buffered somewhat against large-


scale competition as its crop matures earlier than the main production areas in Queensland, and it 
can achieve high returns. Mango production in the NT had a gross value of $129 million in 2020, 
accounting for 38% of the $341 million total value of horticultural production in the NT and half of 
all mangoes produced in Australia (Sangha et al., 2022). 

The perennial nature of tree crops makes a reliable year-round supply of water essential. Some 
species, such as mango and cashew (Anacardium occidentale), can survive well under mild water 
stress until flowering. It is critical for optimum fruit and nut production that trees are not water 
stressed from flowering through to harvest, approximately from June to between November and 
February, depending on plant species and variety. This is a period in the Southern Gulf catchments 
when very little rain falls, and farmers would need to have a system in place to access reliable 
irrigation water during this time. High night-time minimum temperatures can reduce flowering in 
mangoes, although potential production regions in Southern Gulf catchments should not 
experience these temperatures extremes. 

From a land suitability perspective, intensive horticultural tree crops such as mango are included 
in Crop Group 1, the monsoonal tropical tree crops (Table 4-2). Cracking clay soils (Vertosols) make 
up 23% of the catchment; they are principally found on floodplains and alluvial plains of the 
Armraynald Plain and Barkly Tableland physiographic units. Flooding, access and trafficability in 
the wet season are common constraints across the lower parts of the Armraynald Plain and crop 
tolerance to poor soil drainage conditions restricts wet-season cropping in these areas. Effective 
rooting depth is deep to very deep (1.2 to 1.5 m) and the clay texture means the soils have a very 
high (>220 mm) soil AWC. Much of this area is suitable (with moderate or minor limitations) for 
spray irrigation in the dry season, but inadequate drainage in the wet season substantially reduces 
the area suitable for wet-season spray irrigation. Sandy soils have formed on the Doomadgee Plain 
(marked S1 and S4 on Figure 2-5) and the Gulf Fall (marked S3 on Figure 2-5). In total, the red, 
brown, yellow and grey sandy soils make up 10% of the area. Friable non-cracking clay or clay 
loam soils found along the middle reaches of the Leichhardt River make up only about 3% of the 
area but have potential for agriculture, as do the loamy soils (less than 3% of the area) on the 
Nicholson River, the Doomadgee and Cloncurry plains and other isolated areas. Shallow and/or 
rocky soils make up 56% of the catchments and are unsuitable by definition. 

A wide range of horticultural tree crops are considered in the land suitability analysis (crop groups 
1, 2, 20 and 21; Table 4-2; Figure 4-26). Assuming unconstrained development, between about 
860,000 ha (papaya/cashew/macadamia) and 3.9 million ha (e.g. mango) of the Southern Gulf 
catchments is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better 
(Class 2 or Class 1) using spray or trickle irrigation. Furrow irrigation was not considered for 
horticultural tree crops. 

Specialised equipment is required for fruit and nut tree production. The requirement for a timely 
and significant labour force necessitates a system for attracting, managing and retaining sufficient 
staff. In a remote location the cost of providing accommodation to such staff may be significant. 
Tree-pruning and packing equipment is highly specialised for the fruit industry, as are the micro 
irrigation systems typically used in horticulture. 

Table 4-24 describes some key considerations relating to mango production (Figure 4-27) in the 
Southern Gulf catchments, as an exemplar of the considerations relating to tree crop production 


more broadly. Similar information for other fruit tree crops is described in the companion 
technical report on agricultural viability and socio-economics (Webster et al., 2024). 

 

Suitability map for crop synopses
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\4_S_Gulf\1_GIS\1_Map_Docs\1_Export\CR-S-Ch4-509_Suit_Mango_Lime_v1.png
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 4-26 Modelled land suitability for (a) mango (Crop Group 1) and (b) lime (Crop Group 2), both grown using 
trickle irrigation 

These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The 
methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital 
soil mapping and land suitability (Thomas et al., 2024). 

 


Figure 4-27 Mango 

Photo: Shutterstock 


Table 4-24 Summary information relevant to tree crop horticulture production, with mango as an example 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
PVR = plant variety rights. 

 


4.4.9 Plantation tree crops (silviculture) 

Of the plantation tree crops that could be grown in the Southern Gulf catchments, Indian 
sandalwood (Santalum album) and African mahogany (Khaya spp.) are likely to be the most 
economically feasible. Many other plantation species could be grown but returns are much lower 
than for sandalwood or African mahogany. African mahogany is well established in plantations 
near Katherine and in north Queensland. Indian sandalwood is grown in the Ord River Irrigation 
Area (WA), around Katherine (NT) and in northern Queensland. 

Plantation tree crops require over 15 years to mature, but once established they can tolerate 
prolonged dry periods. Irrigation water is critical in the establishment and in the first 2 years of a 
plantation for a number of species. In the case of Indian sandalwood (which is a hemi root 
parasite), the provision of water is for not only the trees themselves but also the leguminous host 
plant. 

From a land suitability perspective, plantation tree crops such as Indian sandalwood, African 
mahogany and teak (Tectona grandis) are included in crop groups 15, 16 and 17 (Table 4-2). 
Cracking clay soils (Vertosols) make up 23% of the catchment; they are principally found on 
floodplains and alluvial plains of the Armraynald Plain and Barkly Tableland physiographic units. 
Flooding, access and trafficability in the wet season are common constraints across the lower 
parts of the Armraynald Plain and crop tolerance to poor soil drainage conditions restricts wet-
season cropping in these areas. Effective rooting depth is deep to very deep (1.2 to 1.5 m) and the 
clay texture means the soils have a very high (>220 mm) soil AWC. Much of this area is suitable 
(with moderate or minor limitations) for spray irrigation in the dry season, but inadequate 
drainage in the wet season substantially reduces the area suitable for wet-season spray irrigation. 
Sandy soils have formed on the Doomadgee Plain (marked S1 and S4 on Figure 2-5) and the Gulf 
Fall (marked S3 on Figure 2-5). In total, the red, brown, yellow and grey sandy soils make up 10% 
of the area. Friable non-cracking clay or clay loam soils found along the middle reaches of the 
Leichhardt River make up only about 3% of the area but have potential for agriculture, as do the 
loamy soils (less than 3% of the area) on the Nicholson River, the Doomadgee and Cloncurry plains 
and other isolated areas. Shallow and/or rocky soils make up 56% of the catchments and are 
unsuitable by definition. 

Depending on the specific tree species being planted and their tolerance to poorly drained soils 
and waterlogging, the suitable areas vary considerably. A range of silviculture trees were 
considered in the land suitability analysis (crop groups 15, 16 and 17; Table 4-2). Assuming 
unconstrained development, between about 3.1 million ha (teak) and 5.1 million ha (African 
mahogany) of the Southern Gulf catchments is considered to be suitable with moderate 
limitations (Class 3; Table 4-1) or better (Class 2 or Class 1) using trickle irrigation (Figure 4-28). 
Furrow irrigation was considered for Indian sandalwood only and about 810,000 ha was assessed 
as suitable with moderate limitations. Table 4-25 describes Indian sandalwood production (Figure 
4-29). 


 

Suitability map for crop synopses
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\4_S_Gulf\1_GIS\1_Map_Docs\1_Export\CR-S-Ch4-510_Suit_IndSand_IndSand_v1.png
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 4-28 Modelled land suitability for Indian sandalwood (Crop Group 15) grown using (a) trickle or (b) furrow 
irrigation 

These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The 
methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital 
soil mapping and land suitability (Thomas et al., 2024). 

 

Indian sandalwood and host plants
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 4-29 Indian sandalwood and host plants 

Indian sandalwood trees are those with a darker trunk and leaves, in a line left of centre in the image. 

Photo: CSIRO 


Table 4-25 Summary information for Indian sandalwood production 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au
4.4.10 Niche crops 

Niche crops such as guar, chia, quinoa (Chenopodium quinoa), bush products and others may be 
feasible in the Southern Gulf catchments, but limited verified agronomic or market data are 
available for these crops. Niche crops are niche due to the limited demand for their products. As a 
result, small-scale production can lead to very attractive prices, but only a small increase in 
productive area can flood the market, leading to greatly reduced prices and making production 
unsustainable. 

There is growing interest in bush products but insufficient publicly available information for 
inclusion with the analyses of irrigated crop options in this report. Bush product production 
systems could take many forms, from culturally appropriate wild harvesting targeting Indigenous 
cultural and environmental co-benefits to intensive mechanised farming and processing, 
resembling something like macadamia (Macadamia integrifolia) farming, with multiple possible 
combinations and variants in between. The choice of production system would have implications 
for the extent of Indigenous participation in each stage of the supply chain (farming, processing, 
marketing and/or consumption), the co-benefits that could be achieved, the scale of the markets 
that could be accessed (in turn affecting the scale of the industry for that bush product), the price 
premiums that produce may be able to attract and the viability of those industries. The current 
publicly available information on bush products mainly focuses on eliciting Indigenous aspirations, 
biochemical analysis (for safety, nutrition and efficacy of potential health benefits of botanicals), 
and considerations of safeguarding Indigenous intellectual property (e.g. Woodward et al., 2019). 
Analysing bush products in a comparable way to other crop options in this report would first 
require these issues to be resolved, for communities to agree on the preferred type of production 
systems (and pathways for development), and for agronomic information on yields, production 
practices and costs to be publicly available. 

Past research on guar has been conducted in the NT, and trials are underway in northern 
Queensland, which could prove future feasibility. There is increasing interest in non-leguminous, 
small-seeded crops such as chia and quinoa, which have high nutritive value. The market size for 
these niche crops is quite small compared with cereals and pulses, so the scale of production is 
likely to be small in the short to medium term. 

There is a small, established chia industry in the Ord River Irrigation Area of WA, but its production 
and marketing statistics are largely commercial-in-confidence. Nearly all Australian production of 
chia is contracted to The Chia Company of Australia or is exported to China. In Australia, The Chia 
Company produces whole chia seeds, chia bran, ground chia seed and chia oil for wholesale and 
retail sale, and it exports these products to 36 countries. 


The growing popularity of quinoa in recent years is attached to its marketing as a superfood. It is 
genetically diverse and has not been the subject of long-term breeding programs. This diversity 
means it is well suited to a range of environments, including northern Australia, where its greatest 
opportunity is as a short-season crop in the dry season under irrigation. It is a high-value crop with 
farm gate prices of about $1000/t. Trials of quinoa production have been conducted at the 
Katherine Research Station in the NT (approximately 600 km north-west of the Southern Gulf 
catchments), with reasonable yields being returned. More trials are required in the various 
northern environments before quinoa could be recommended for commercial production. 

4.5 Aquaculture 

4.5.1 Introduction 

There are considerable opportunities for aquaculture development in northern Australia given its 
natural advantages of a climate suited to farming valuable tropical species, large areas identified 
as suitable for aquaculture, political stability and proximity to large global markets. The main 
challenges to developing and operating modern and sustainable aquaculture enterprises are 
regulatory issues, global cost competitiveness and the remoteness of much of the suitable land 
area. A comprehensive situational analysis of the aquaculture industry in northern Australia 
(Cobcroft et al., 2020) identifies key challenges, opportunities and emerging sectors. This section 
draws on a recent assessment of the opportunities for aquaculture in northern Australia in the 
Northern Australia Water Resource Assessment technical report on aquaculture (Irvin et al., 2018), 
summarising the three most likely candidate species (Section 4.5.2), overviewing production 
systems (Section 4.5.3), land suitability for aquaculture within the Southern Gulf catchments 
(Section 4.5.4) and the financial viability of different options for aquaculture development (Section 
4.5.5). 

4.5.2 Candidate species 

The three species with the most aquaculture potential in the catchments of the Southern Gulf 
rivers are black tiger prawns (Penaeus monodon), barramundi (Lates calcarifer), and red claw 
(Cherax quadricarinatus). The first two species are suited to many marine and brackish water 
environments of northern Australia and have established land-based culture practices and well-
established markets for harvested products. Prawns could potentially be cultured in either 
extensive (low density, low input) or intensive (higher density, higher input) pond-based systems 
in northern Australia, whereas land-based culture of barramundi would likely be intensive. Red 
claw is a freshwater crayfish that is currently cultured by a much smaller industry than the other 
two species. 

Black tiger prawns 

Black tiger prawns (Figure 4-30) are found naturally at low abundances across the waters of the 
western Indo-Pacific region, with wild Australian populations making up the southernmost extent 
of the species. Within Australia, the species is most common in the tropical north, but does occur 
at lower latitudes. 


 


Figure 4-30 Black tiger prawns 

Photo: CSIRO 

Barramundi 

Barramundi (Figure 4-31) is the most highly produced and valuable tropical fish species in 
Australian aquaculture. Barramundi inhabit the tropical north of Australia from the Exmouth Gulf 
in WA through to the Noosa River on Queensland’s east coast. It is also commonly known as the 
‘Asian sea bass’ or ‘giant sea perch’ throughout its natural areas of distribution in the Persian Gulf, 
the western Indo-Pacific region and southern China (Schipp et al., 2007). The attributes that make 
barramundi an excellent aquaculture candidate are fast growth (reaching 1 kg or more in 12 
months), year-round fingerling availability, well-established production methods and hardiness 
(i.e. they have a tolerance to low oxygen levels, high stocking densities and handling, as well as a 
wide range of temperatures) (Schipp et al., 2007). In addition, barramundi are euryhaline (able to 
thrive and be cultured in fresh and marine water), but freshwater barramundi can have an earthy 
flavour. 

 


Figure 4-31 Barramundi 

Photo: CSIRO 


Red claw 

Red claw is a warm-water crayfish species that inhabits still or slow-moving water bodies. The 
natural distribution of red claw is from the tropical catchments of Queensland and the NT to 
southern New Guinea. The name ‘red claw’ is derived from the distinctive red markings present on 
the claws of the male crayfish. The traits of red claw that make them attractive for aquaculture 
production are a simple life cycle, which is beneficial because complex hatchery technology is not 
required (Jones et al., 1998); their tolerance of low oxygen levels (<2 mg/L), which is beneficial in 
terms of handling, grading and transport (Masser and Rouse, 1997); their broad thermal tolerance, 
with optimal growth achievable between 23 and 31 °C; and their ability to remain alive out of 
water for extended periods. 

4.5.3 Production systems 

Overview 

Aquaculture production systems can be broadly classified into extensive, semi-intensive and 
intensive systems. Intensive systems require high inputs and expect high outputs: they require 
high capital outlay and have high running costs; they require specially formulated feed and 
specialised breeding, water quality and biosecurity processes; and they have high production per 
hectare (in the order of 5000 to 20,000 kg per ha per crop). Semi-intensive systems involve 
stocking seed from a hatchery, routine provision of a feed, and monitoring and management of 
water quality. Production is typically 1000 to 5000 kg per ha per crop. Extensive systems are 
characterised by low inputs and low outputs: they require less-sophisticated management and 
often require no supplementary feed because the farmed species live on naturally produced feed 
in open-air ponds. Extensive systems produce about half the volume of global aquaculture 
production, but there are few commercial operations in Australia. 

Water salinity and temperature are the key parameters that determine species selection and 
production potential for any given location. Suboptimal water temperature (even within tolerable 
limits) will prolong the production season (because of slow growth) and increase the risk of 
disease, reducing profitability. 

The primary culture units for land-based farming are purpose-built ponds. Pond structures 
typically include an intake channel, production pond, discharge channel and a bioremediation 
pond (Figure 4-32). The function of the pond is as a containment structure – an impermeable layer 
between the pond water and the local surface water and groundwater. Optimal sites for farms are 
flat and have sufficient elevation to enable ponds to be completely drained between seasons. It is 
critical that all ponds and channels can be fully drained during the off (dry-out) season to enable 
machinery access to sterilise and undertake pond maintenance. 


 


Figure 4-32 Schematic of marine aquaculture farm 

Most production ponds in Australia are earthen. Soils for earthen ponds should have low 
permeability and high structural stability. Ponds should be lined if the soils are permeable. 
Synthetic liners have a higher capital cost but are often used in more-intensive operations, which 
require high levels of aeration – conditions that would lead to significant erosion in earthen ponds. 

Farms use aerators (typically electric paddlewheels and aspirators) to help maintain optimal water 
quality in the pond, provide oxygen and create a current that consolidates waste into a central 
sludge pile (while keeping the rest of the pond floor clear). A medium-sized (50 ha) prawn farm in 
Australia uses around 4 GWh annually, accounting for most of an enterprise’s energy use 
(Paterson and Miller, 2013). Backup power capacity sufficient to run all the aerators on the farm, 
usually with a diesel generator, is essential to be able to cope with power failures. Extensive 
production systems do not require aeration in most cases. 

Black tiger prawns 

A typical pond in the Australian black tiger prawn industry is rectangular, about 1 ha in area and 
about 1.5 m in depth. The ponds are either wholly earthen, lined on the banks with black plastic 
and earthen bottoms or (rarely in Australia) fully lined. Pond grow-out of black tiger prawns 
typically operates at stocking densities of 25 to 50 individuals per square metre (termed ‘intensive’ 
in this report). These pond systems are fitted with multiple aeration units, which could double 
from 8 to 16 units as the biomass of the prawn crop increases (Mann, 2012). 

At the start of each prawn crop, pond bottoms are dried, and unwanted sludge from the previous 
crop is removed. If needed, additional substrate is added. Before filling the ponds, lime is often 
added to buffer pH, particularly in areas with acid-sulfate soils. The ponds are then filled with 
filtered seawater and left for about 1 week prior to postlarval stocking. Algal blooms in the water 
are encouraged through addition of organic fertiliser to provide shading for prawns, discourage 
benthic algal growth and stimulate growth of plankton as a source of nutrition (QDPIF, 2006). 
Postlarvae are purchased from hatcheries and grow rapidly into small prawns in the first month 


after stocking, relying mainly on the natural productivity (zooplankton, copepods and algae) 
supported by the algal bloom for their nutrition. Approximately 1 month after the prawns are 
stocked, pellet feed becomes the primary nutrition source. Feed is a major cost of prawn 
production: around 1.5 kg of feed is required to produce 1 kg of prawns. Prawns typically reach 
optimal marketable size (30 g) within 6 months. After harvest, prawns are usually processed 
immediately, with larger farms having their own production facilities that enable grading, cooking, 
packaging and freezing. 

Effective prawn farm management involves maintaining optimal water quality conditions, which 
becomes progressively complex as prawn biomass and the quantity of feed added to the system 
increase. As prawn biomass increases, so too does the biological oxygen demand of the microbial 
population within the pond that is breaking down organic materials. This requires increases in 
mechanical aeration and water exchanges (either fresh or recycled from a bioremediation pond). 
In most cases water salinity is not managed, except through seawater exchange, and will increase 
naturally with evaporation and decrease with rainfall and flooding. Strict regulation of the quality 
and volume of water that can be discharged means efficient use of water is standard industry 
practice. Most Australian prawn farms allocate up to 30% of their productive land for water 
treatment by pre-release containment in settlement systems. 

Barramundi 

The main factors that determine productivity of barramundi farms are water temperature, 
dissolved oxygen levels, effectiveness of waste removal, expertise of farm staff and the overall 
health of the stock. Barramundi are susceptible to a variety of bacterial, fungal and parasitic 
organisms. They are at highest risk of disease when exposed to suboptimal water quality 
conditions (e.g. low oxygen or extreme temperatures). 

Due to the cost and infrastructure required, many producers elect to purchase barramundi 
fingerlings from independent hatcheries, moving fish straight into their nursery cycle. Regular size 
grading is essential during the nursery stage to minimise aggressive and cannibalistic behaviour: 
size grading helps to prevent mortalities and damage from predation on smaller fish, and it assists 
with consistent growth. 

Ponds are typically stocked to a biomass of about 3 kg per 1000 L. Under optimal conditions 
barramundi can grow to over 1 kg in 12 months and to 3 kg within 2 years (Schipp et al., 2007). 
The two largest Australian aquafeed manufacturers (located in Brisbane and Hobart) each produce 
a pellet feed that provides a specific diet promoting efficient growth and feed conversion. The 
industry relies heavily on these mills to provide a regular supply of high-quality feed. Cost of feed 
transport would be a major cost to barramundi production in the Southern Gulf catchments. As a 
carnivorous species, high dietary protein levels, with fishmeal as a primary ingredient, are required 
for optimal growth. Barramundi typically require between 1.2 and 1.5 kg of pelleted feed for each 
kilogram of body weight produced. 

Warm water temperatures in northern Australia enable fish to be stocked in ponds year round. 
Depending on the intended market, harvested product is processed whole or as fillets and 
delivered fresh (refrigerated or in ice slurry) or frozen. Smaller niche markets for live barramundi 
are available for Asian restaurants in some capital cities. 


Red claw 

Water temperature and feed availability are the variables that most affect crayfish growth. Red 
claw are a robust species but are most susceptible to disease (including viruses, fungi, protozoa 
and bacteria) when conditions in the production pond are suboptimal (Jones, 1995). In tropical 
regions, mature females can be egg-bearing year round. Red claw breed freely in production 
ponds, so complex hatchery technology (or buying juvenile stock) is not required. However, low 
fecundity and the associated inability to source high numbers of quality selected broodstock are 
an impediment to intensive expansion of the industry. Production ponds are earthen, rectangular 
in design and on average 1 ha in size. They slope in depth from 1.2 to 1.8 m. Sheeting is used on 
the pond edge to keep the red claw in the pond (they tend to migrate), and netting surrounds the 
pond to protect stock from predators (Jones et al., 2000). 

At the start of each crop, ponds are prepared (as for black tiger prawns above), then filled with 
fresh water and left for about 2 weeks before stocking. During this period, algal blooms in the 
water are encouraged through addition of organic fertiliser. Ponds are then stocked with about 
250 females and 100 males that have reached sexual maturity. Natural mating results in the 
production of around 20,000 advanced juveniles. Red claw are omnivorous, foraging on natural 
production such as microbial biomass associated with decaying plants and animals. Early-stage 
crayfish rely almost solely on natural pond productivity (phytoplankton and zooplankton) for 
nutrition. As the crayfish progress through the juvenile stages, the greater part of the diet changes 
to organic particulates (detritus) on the bottom of the pond. Very small quantities of a commercial 
feed are added daily to assist with the weaning process and provide an energy source for the pond 
bloom. Providing adequate shelters (net bundles) is essential at this stage to improve survival 
(Jones, 2007). Approximately 4 months after stocking, the juveniles are harvested and graded by 
size and sex for stocking in production ponds. 

Juveniles are stocked in production ponds at 5 to 10 per square metre. Shelters are important 
during the grow-out stage, with 250/ha recommended. During the grow-out phase, pellet feed 
becomes an important nutrition source, along with the natural productivity provided by the pond. 
Current commercial feeds are low cost and provide a nutrition source for natural pond 
productivity as much as for the crayfish. Most Australian farmers use diets consisting of 25% to 
30% protein. Effective farm management involves maintaining water quality conditions within 
ranges optimal for crayfish growth and survival as pond biomass increases. As with barramundi, 
management involves increasing aeration and water exchanges, while strictly managing effluent 
discharges. Red claw are harvested within 6 months of stocking to avoid reproduction in the 
production pond. At this stage the crayfish will range from 30 to 80 g. Stock are graded by size and 
sex into groups for market, breeding or further grow-out (Jones, 2007). 

Estimated water use 

An average crop of prawns farmed in intensive pond systems (8 t/ha over 150 days) is estimated 
to require 127 ML of marine water, which equates to 15.9 ML of marine water for each tonne of 
harvested product (Irvin et al., 2018). For pond culture of barramundi (30 t/ha over 2 years), 
562 ML of marine water, or fresh water, is required per crop, equating to 18.7 ML of water for 
each tonne of harvested fish. For extensive red claw culture (3 t/ha over 300 days), 240 ML of 
fresh water is required per pond crop, equating to 16 ML of water for each harvested tonne of 
crayfish (Irvin et al., 2018). 


4.5.4 Aquaculture land suitability 

The suitability of areas for aquaculture development was also assessed from the perspective of 
soil and land characteristics using the set of five land suitability classes in Table 4-1. The limitations 
considered include clay content, soil surface pH, soil thickness and rockiness. Limitations mainly 
relate to geotechnical considerations (e.g. construction and stability of impoundments). Other 
limitations, including slope, and the likely presence of gilgai microrelief and acid-sulfate soils, are 
indicative of more difficult, expensive and therefore less suitable development environments, and 
a greater degree of land preparation effort. More detail can be found in the companion technical 
report on digital soil mapping and land suitability (Thomas et al., 2024). 

Suitability was assessed for lined and earthen ponds, with earthen ponds requiring soil properties 
that prevent pond leakage. Soil acidity (pH) was also considered for earthen ponds, as some 
aquaculture species can be affected by unfavourable pH values exchanged into the water column 
(i.e. biological limitation). Two aquaculture species were selected to represent the environmental 
needs of marine species (represented by prawns) and freshwater species (red claw). Additionally, 
barramundi and other euryhaline species, which can tolerate a range of salinity conditions, may be 
suited to either marine or fresh water, depending on management choices. Except for aquaculture 
of marine species, which for practical purposes is restricted by proximity to sea water, no 
consideration was given in the analysis to proximity to suitable water for aquaculture of fresh and 
euryhaline species. It was not possible to include proximity to fresh water due to the large number 
of potential locations where water could be captured and stored within the catchments. Note also 
that the estimates for land suitability presented below represent the total areas of the catchments 
unconstrained by factors such as water availability, land tenure, environmental and other 
legislation and regulations, and a range of biophysical risks such as cyclones and flooding. These 
are addressed elsewhere by the Assessment. The land suitability maps are designed to be used 
predominantly at the regional scale. Planning at the enterprise scale would demand more localised 
assessment. 

Analysis of suitability of land for marine aquaculture has been restricted to locations within 2 km 
of a marine water source. Marine aquaculture land suitability is shown in Figure 4-33 and presents 
suitability across the areas under tidal influence and river margins where cracking clay (SGG 9) and 
seasonally or permanently wet soils (SGG 3) dominate. These soils show the desired land surface 
characteristics such as no rockiness, suitable slope and sufficient soil thickness, but they have the 
risk of acid-sulfate soils and must be managed accordingly. 

Suitable land for marine aquaculture in lined ponds (Figure 4-33a) totals 300,206 ha (2.8% of the 
catchments) and is restricted to the Karumba Plain physiographic unit where SGG 3 (seasonally or 
permanently wet) soils dominate, representing largely Class 2 land (86,000 ha, 0.8%). The suitable 
area extends into some of the most downstream areas of the Armraynald Plain physiographic unit, 
where tidal influence is still felt, and coincides with the presence of SGG 9 soils (cracking clays). 

The land suitability patterns for marine species in earthen ponds (Figure 4-33b) closely mirror 
those of the marine lined ponds, although areas are restricted to slowly permeable cracking clay 
soils. Approximately 193,600 ha (1.8% of the catchments) is mapped as suitability Class 3, where 
the possibility for earthen ponds depends on soil factors including sufficient depth, low soil 
permeability and heavier surface textures. 


 

Marine aquaculture suitability map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\3_Land_suitability\4_S_Gulf\1_GIS\1_Map_docs\LL-S-535_Aquaculture_marine_v1_Arc10_8.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 4-33 Land suitability in the Southern Gulf catchments for marine species aquaculture in (a) lined ponds and 
(b) earthen ponds 

These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The 
methods used to derive the suitability data are outlined in the companion technical report on digital soil mapping and 
land suitability (Thomas et al., 2024). 

The aquaculture land suitability analyses for freshwater species do not consider availability of 
fresh water for production, only soil and land attributes (Figure 4-34). This shows that a significant 
proportion of the catchments is suitable for freshwater aquaculture in lined ponds (6,265,400 ha, 
57.9%; Figure 4-34a), with the unsuitable areas associated with higher slopes and shallow and/or 
rocky soils (SGG 7). The suitable area includes the low slope, deep and non-rocky parts of all SGGs 
except SGG 7, and the majority of the area is Class 2 (suitable with minor limitations) 5,154,300 ha 
(47.6%), with smaller proportions of Class 1 (40,300 ha, 0.4%) and Class 3 (1,070,800 ha, 9.9%). 

In comparison, opportunities for freshwater species in earthen ponds in the Assessment area are 
more restricted: 2,408,273 ha (22.3%) of which only 170 ha is Class 2 (Figure 4-34b). Shallow 
and/or rocky (SGG 7) and moderately to highly permeable soils are unsuited to earthen water 
impoundments. The suitable areas match the cracking clay soils (SGG 9) distribution as these soils 
provide the necessary soil conditions including depth, slower permeability and clay textured 
surface soils. There are also significant areas on the Karumba Plain of slowly permeable seasonally 
or permanently wet (SGG 3) and cracking clay (SGG 9) soils. These coastal plains have potential 
acid-sulfate soils that would require appropriate management. 




Freshwater aquaculture suitability map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\3_Land_suitability\4_S_Gulf\1_GIS\1_Map_docs\LL-S-534_Aquaculture_fresh_v2_Arc10_8.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 4-34 Land suitability in the Southern Gulf catchments for freshwater species aquaculture in (a) lined ponds 
and (b) earthen ponds 

These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The 
methods used to derive the suitability data are outlined in the companion technical report on digital soil mapping and 
land suitability (Thomas et al., 2024). 

4.5.5 Aquaculture viability 

This section provides a brief, generic analysis of what would be required for new aquaculture 
developments in the Southern Gulf catchments to be financially viable. First, indicative costs are 
provided for a range of four possible aquaculture enterprises that differ in species farmed, scale 
and intensity of production. The cost structure of the enterprises was based on established tools 
available from the Queensland Government for assessing the performance of existing or proposed 
aquaculture businesses (Queensland Government, 2024). Based on the ranges of these indicative 
capital and operating costs, gross revenue targets that a business would need to attain to be 
commercially viable are then calculated. 

Enterprise-level costs for aquaculture development 

Costs of establishing and running a new aquaculture business are divided here into the initial 
capital costs of development and ongoing operating costs. The four enterprise types analysed 
were chosen to portray some of the variation in cost structures between potential development 
options, not as a like-for-like comparison between different types of aquaculture (Table 4-26). 


Table 4-26 Indicative capital and operating costs for a range of generic aquaculture development options 

Costs are provided both per hectare of grow-out pond and per kilogram of harvested produce, although capital costs 
scale mostly with the area developed, and operating costs scale mainly with crop yield at harvest. Capital costs have 
been converted to an equivalent annualised cost assuming a 10% discount rate and that a quarter of the developed 
infrastructure was for 15-year life span assets and the remainder for 40-year life span assets. Indicative breakdowns of 
cost components are provided on a proportional basis. 

PARAMETER 

UNIT 

PRAWN 
(EXTENSIVE) 

PRAWN 
(INTENSIVE) 

BARRAMUNDI 

RED CLAW 
(SMALL SCALE) 

Scale of development 











Grow-out pond area 

ha 

20 

100 

30 

4 

Total farm area 

ha 

25 

150 

100 

10 

Yield at harvest 

t/y 

30 

800 

600 

32 

Yield at harvest per pond area 

t/ha/y 

1.5 

8.0 

20.0 

3.0 

Capital costs of development (scale with area of grow-out ponds developed) 

Land and buildings 

% 

56 

26 

23 

30 

Vehicles 

% 

5 

2 

2 

11 

Pond-related assets 

% 

27 

67 

70 

41 

Other infrastructure and 
equipment 

% 

11 

6 

5 

17 

Total capital cost (year 0) 

$/ha 

74,000 

142,000 

147,000 

163,000 

Equivalent annualised cost 

$/kg 

5.41 

1.94 

0.81 

5.95 



$/ha/y 

8,108 

15,558 

16,106 

17,859 

Operating costs (vary with yield at harvest, except overheads) 

Nursery/juvenile costs 

% 

12 

9 

7 

1 

Feed costs 

% 

0 

26 

30 

8 

Labour costs 

% 

47 

13 

12 

57 

Electricity costs 

% 

16 

24 

30 

9 

Packing costs 

% 

2 

4 

3 

2 

Transport costs 

% 

6 

16 

16 

11 

Overhead costs (fixed) 

% 

17 

8 

1 

12 

Total annual operating costs 

$/kg 

19.31 

12.47 

12.46 

17.80 



$/ha/y 

28,966 

99,783 

249,211 

53,402 

Total costs of production 

Total annual cost 

$/kg 

24.72 

14.42 

13.27 

23.75 



$/ha/y 

37,100 

115,300 

265,300 

71,300 






Capital costs include all land development costs, construction, and plant and equipment 
accounted for in the year production commences. The types of capital development costs are 
largely similar across the aquaculture options, with costs of constructing ponds and buildings 
dominating the total initial capital investment. Indicative costs were derived from the case study 
of Guy et al. (2014), and consultation with experts familiar with the different types of aquaculture, 
including updating to December 2023 dollar values (Table 4-26). 

Operating costs cover both overheads (which do not change with output) and variable costs 
(which increase as the yield of produce increases). Fixed overhead costs in aquaculture are a 
relatively small component of the total costs of production. Overheads consist of costs relating to 
licensing, approvals and other administration (Table 4-26). 

The remaining operating costs are variable (Table 4-26). Feed, labour and electricity typically 
dominate the variable costs. Aquaculture requires large volumes of feed inputs, and the efficiency 
with which this feed is converted to marketed produce is a key metric of business performance. 
Labour costs consist of salaries of permanent staff and casual staff who are employed to cover 
intensive harvesting and processing activities. Aerators require large amounts of energy, 
increasing as the biomass of produce in the ponds increases, which accounts for the large costs of 
electricity. Transport, although a smaller proportional cost, is important because this puts remote 
locations at a disadvantage relative to aquaculture businesses that are closer to feed suppliers and 
markets. In addition, transport costs may be higher at times if roads are cut (requiring much more 
expensive air freight or alternative, longer road routes) or if the closest markets become 
oversupplied. Packing is the smallest component of variable costs in the breakdown categories 
used here. 

Revenue for aquaculture produce typically ranges from $10 to $20 per kg (on a harvested mass 
basis), but prices vary depending on the quality and size classes of harvested animals and how 
they are processed (e.g. live, fresh, frozen or filleted). Farms are likely to deliver a mix of products 
targeted to the specifications of the markets they supply. Note that the mass of sold product may 
be substantially lower than the harvested product (e.g. fish fillets are about half the mass of 
harvested fish), so prices of sold product may not be directly comparable to the costs of 
production in Table 4-26, which are on a harvest mass basis. 

Commercial viability of new aquaculture developments 

Capital and operating costs differ between different types of aquaculture enterprises (Table 4-27), 
but these costs may differ even more between locations (depending on case-specific factors such 
as remoteness, soil properties, distance to water source and type of power supply). Furthermore, 
there can be considerable uncertainty in some costs, and prices paid for produce can fluctuate 
substantially over time. Given this variation among possible aquaculture developments in the 
Southern Gulf catchments, a generic approach was taken to determine what would be required 
for new aquaculture enterprises to become commercially viable. The approach used here was to 
calculate the gross revenue that an enterprise would have to generate each year to achieve a 
target internal rate of return (IRR) for given operating costs and development costs (both 
expressed per hectare of grow-out ponds). Capital costs were converted to annualised equivalents 
on the assumption that developed assets equated to a mix of 25% 15-year assets and 75% assets 
with a 40-year life span (using a discount rate matching the target IRR). The target gross revenue is 






the sum of the annual operating costs and the equivalent annualised cost of the infrastructure 
development (Table 4-27). 
Table 4-27 Gross revenue targets required to achieve target internal rates of return (IRR) for aquaculture 
developments with different combinations of capital costs and operating costs 
All values are expressed per hectare of grow-out ponds in the development. Gross revenue is the yield per hectare of 
pond multiplied by the price received for produce (averaged across products and on a harvest mass basis). Capital 
costs were converted to an equivalent annualised cost assuming a quarter of the developed infrastructure was for 
15-year life span assets and the remainder for 40-year life span assets. Targets would be higher after taking into 
account risks such as initial learning and market fluctuations. 

OPERATING 
COSTS 
($/ha/y) 

GROSS REVENUE REQUIRED TO ACHIEVE TARGET IRR ($/ha/y) 



Capital costs of development ($/ha) 



60,000 

70,000 

80,000 

90,000 

100,000 

110,000 

125,000 

150,000 

175,000 

7% target IRR 

20,000 

25,022 

25,859 

26,696 

27,533 

28,371 

29,208 

30,463 

32,556 

34,648 

50,000 

55,022 

55,859 

56,696 

57,533 

58,371 

59,208 

60,463 

62,556 

64,648 

100,000 

105,022 

105,859 

106,696 

107,533 

108,371 

109,208 

110,463 

112,556 

114,648 

150,000 

155,022 

155,859 

156,696 

157,533 

158,371 

159,208 

160,463 

162,556 

164,648 

200,000 

205,022 

205,859 

206,696 

207,533 

208,371 

209,208 

210,463 

212,556 

214,648 

250,000 

255,022 

255,859 

256,696 

257,533 

258,371 

259,208 

260,463 

262,556 

264,648 

10% target IRR 

20,000 

26,574 

27,669 

28,765 

29,861 

30,956 

32,052 

33,695 

36,434 

39,174 

50,000 

56,574 

57,669 

58,765 

59,861 

60,956 

62,052 

63,695 

66,434 

69,174 

100,000 

106,574 

107,669 

108,765 

109,861 

110,956 

112,052 

113,695 

116,434 

119,174 

150,000 

156,574 

157,669 

158,765 

159,861 

160,956 

162,052 

163,695 

166,434 

169,174 

200,000 

206,574 

207,669 

208,765 

209,861 

210,956 

212,052 

213,695 

216,434 

219,174 

250,000 

256,574 

257,669 

258,765 

259,861 

260,956 

262,052 

263,695 

266,434 

269,174 

14% target IRR 

20,000 

28,776 

30,238 

31,701 

33,163 

34,626 

36,089 

38,283 

41,939 

45,596 

50,000 

58,776 

60,238 

61,701 

63,163 

64,626 

66,089 

68,283 

71,939 

75,596 

100,000 

108,776 

110,238 

111,701 

113,163 

114,626 

116,089 

118,283 

121,939 

125,596 

150,000 

158,776 

160,238 

161,701 

163,163 

164,626 

166,089 

168,283 

171,939 

175,596 

200,000 

208,776 

210,238 

211,701 

213,163 

214,626 

216,089 

218,283 

221,939 

225,596 

250,000 

258,776 

260,238 

261,701 

263,163 

264,626 

266,089 

268,283 

271,939 

275,596 






In order for an enterprise to be commercially viable, the volume of produce grown each year 
multiplied by the sales price of that produce would need to match or exceed the target values 
provided above. For example, a proposed development with capital costs of $125,000/ha and 
operating costs of $200,000 per ha per year would need to generate gross revenue of $213,695 
per ha per year to achieve a target IRR of 10% (Table 4-27). If the enterprise received $12/kg for 
produce (averaged across product types, on a harvest mass basis), then it would need to sustain 
mean long-term yields of 18 t/ha (= $213,695 per ha per year ÷ $12/kg × 1 t/1000 kg) from the first 
harvest. However, if prices were $20/kg, mean long-term yields would require 11 t/ha (= $213,695 
per ha per year ÷ $20/kg × 1 t/1000 kg) for the same $125,000 capital costs per hectare, or only 
6 t/ha harvests if the capital costs decreased to $100,000 per hectare. Target revenue would be 
higher after taking into account risks such as learning and adapting to the particular challenges of 
a new location, and periodic setbacks that could arise from disease, climate variability, changes in 
market conditions or new legislation. 

Key messages 

From this analysis, a number of key points about achieving commercial viability in new 
aquaculture enterprises are apparent: 

•Operating costs are very high, and the amount spent each year on inputs can exceed the upfront(year zero) capital cost of development (and the value of the farm assets). This means that thecost of development is a much smaller consideration for achieving profitability than ongoingoperations and costs of inputs.
•High operating costs also mean that substantial capital reserves are required, beyond the capitalcosts of development, as there will be large cash outflows for inputs in the start-up years beforerevenue from harvested product starts to be generated. This is particularly the case for largersize classes of product that require multi-year grow-out periods before harvest. Managingcashflows would therefore be an important consideration at establishment and as yields aresubsequently scaled up.
•Variable costs dominate the total costs of aquaculture production, so most costs will increase asyield increases. This means that increases in production, by itself, would contribute little toachieving profitability in a new enterprise. What is much more important is increasingproduction efficiency, such as feed conversion rate or labour efficiency, so inputs per unit ofproduce are reduced (and profit margins per kilogram are increased).
•Small changes in quantities and prices of inputs and produce would have a relatively largeimpact on net profit margins. These values could differ substantially between different locations(e.g. varying in remoteness, available markets, soils and climate) and depend on the experienceof managers. Even small differences from the indicative values provided in Table 4-27couldrender an enterprise unprofitable.
•Enterprise viability would therefore be very dependent on the specifics of each particular caseand how the learning, scaling up and cashflow were managed during the initial establishmentyears of the enterprise. It would be essential for any new aquaculture development in theSouthern Gulf catchments to refine the production system and achieve the required levels ofoperational efficiency (input costs per kilogram of produce) using just a few ponds before scalingany enterprise.



4.6 References 

ABARES (2022) Agricultural commodities: September quarter 2022. Australian Bureau of 
Agricultural and Resource Economics and Sciences, Canberra. DOI: doi.org/10.25814/zs85-
g927. 

ABARES (2023) Australian horticulture prices. Australian Bureau of Agricultural and Resource 
Economics and Sciences, Canberra. Viewed 10 March 2023, 
https://www.agriculture.gov.au/abares/data/weekly-commodity-price-update/australian-
horticulture-prices#daff-page-main. 

Abrecht DG and Bristow KL (1996) Coping with climatic hazards during crop establishment in the 
semi-arid tropics. Australian Journal of Experimental Agriculture 36, 971–983. DOI: 
10.1071/EA9960971. 

Andrews K and Burgess J (2021) Soil and land assessment of the southern part of Flying Fox Station 
for irrigated agriculture. Part B: Digital soil mapping and crop specific land suitability. 
Department of Environment, Parks and Water Security, Northern Territory Government, 
Darwin. 

Arndt W, Phillips LJ and Norman MJT (1963) Comparative performance of crops on three soils of 
the Tipperary region NT. Division of Land Research and Regional Survey Technical Paper No. 
23. CSIRO, Canberra. 

Ash AJ (2014) Factors driving the viability of major cropping investments in Northern Australia – a 
historical analysis. CSIRO, Australia. 

Ash A and Watson I (2018) Developing the north: learning from the past to guide future plans and 
policies. The Rangeland Journal 40, 301–314. DOI: 10.1071/RJ18034 

Barbour L (2008) Analysis of plant-host relationships in tropical sandalwood (Santalum album). 
RIRDC Publication No 08/138. Rural Industries Research and Development Corporation, 
Canberra. Viewed 28 August 2024, https://agrifutures.com.au/product/analysis-of-plant-
host-relationships-in-tropical-sandalwood-santalum-album. 

Cobcroft J, Bell R, Fitzgerald J, Diedrich A and Jerry D (2020) Northern Australia aquaculture 
industry situational analysis. Project A.1.1718119. Cooperative Research Centre for 
Developing Northern Australia, Townsville. 

Gentry J (2010) Mungbean management guide, 2nd edition. Department of Employment, 
Economic Development and Innovation, Queensland. Viewed 19 October 2017, 
https://era.daf.qld.gov.au/id/eprint/7070/1/mung-manual2010-LR.pdf. 

DSITI and DNRM (2015) Guidelines for agricultural land evaluation in Queensland. Queensland 
Government (Department of Science, Information Technology and Innovation and 
Department of Natural Resources and Mines), Brisbane. 

FAO (1976) A framework for land evaluation. Food and Agriculture Organization of the United 
Nations, Rome. 

FAO (1985) Guidelines: land evaluation for irrigated agriculture. Food and Agriculture Organization 
of the United Nations, Rome. 


Gibbs M, Hughes J, Yang A, Wang B, Marvanek S and Petheram C (2024) River model scenario 
analysis for the Southern Gulf catchments. A technical report from the CSIRO Southern Gulf 
Water Resource Assessment for the National Water Grid. CSIRO, Australia. 

Gleeson T, Martin P and Mifsud C (2012) Northern Australian beef industry: assessment of risks 
and opportunities. Australian Bureau of Agricultural and Resource Economics and Sciences 
report to client, prepared for the Northern Australia Ministerial Forum, Canberra. 

Guy JA, McIlgorm A and Waterman P (2014) Aquaculture in regional Australia: responding to trade 
externalities. A northern NSW case study. Journal of Economic & Social Policy 16(1), 115. 

Irvin S, Coman G, Musson D and Doshi A (2018) Aquaculture viability. A technical report to the 
Australian Government from the CSIRO Northern Australia Water Resource Assessment, part 
of the National Water Infrastructure Development Fund: Water Resource Assessments. 
CSIRO, Australia. 

Jakku E, Thorburn PJ, Marshall NA, Dowd AM, Howden SM, Mendham E, Moon K and Brandon C 
(2016) Learning the hard way: a case study of an attempt at agricultural transformation in 
response to climate change. Climatic Change 137, 557–574. DOI: 10.1007/s10584-016-1698-
x 

Jones C (2007) Redclaw package 2007. Introduction to redclaw aquaculture. Queensland 
Department of Primary Industries and Fisheries, Brisbane. 

Jones C, Grady J-A and Queensland Department of Primary Industries (2000) Redclaw from harvest 
to market: a manual of handling procedures. Queensland Department of Primary Industries, 
Brisbane. 

Jones C, Mcphee C and Ruscoe I (1998) Breeding redclaw: management and selection of 
broodstock. QI98016. Queensland Department of Primary Industries, Brisbane. 

Jones CM (1995) Production of juvenile redclaw crayfish, Cherax quadricarinatus (von Martens) 
(Decapoda, Parastacidae) III. Managed pond production trials. Aquaculture 138(1), 247–255. 
DOI: https://doi.org/10.1016/0044-8486(95)00067-4. 

Mann D (2012) Impact of aerator biofouling on farm management, production costs and aerator 
performance. Mid project report to farmers. Australian Seafood Cooperative Research 
Centre Project No. 2011/734. Department of Agriculture, Fisheries and Forestry, 
Queensland. 

Masser M and Rouse B (1997) Australian red claw crayfish. Circular ANR-769. The Alabama 
Cooperative Extension Service, USA. 

McKellar L, Bark RH and Watson I (2015) Agricultural transition and land-use change: 
considerations in the development of irrigated enterprises in the rangelands of northern 
Australia. The Rangeland Journal 37, 445–457. DOI: 10.1071/RJ14129. 

McLean I and Holmes P (2015) Improving the performance of northern beef enterprises, 2nd 
edition. Meat and Livestock Australia, Sydney. 

Moore G, Revell C, Schelfhout C, Ham C and Crouch S (2021) Mosaic agriculture. A guide to 
irrigated crop and forage production in northern WA. Bulletin 4915. Western Australia 
Department of Regional Industries and Regional Development, Perth. 


Paterson B and Miller S (2013) Energy use in shrimp farming, study in Australia keys on aeration 
and pumping demands. Global Aquaculture Advocate, November/December, pp. 30–32. 

QDPIF (2006) Australian prawn farming manual: health management for profit. Queensland 
Department of Primary Industries and Fisheries, Brisbane. 

Queensland Government (2024) Business Queensland, Aquaculture farms and production systems. 
Viewed 15 June 2024, https://publications.qld.gov.au/dataset/agbiz-tools-fisheries-
aquaculture. 

Sangha KK, Ahammad R, Mazahar MS, Hall M, Owens G, Kruss L, Verrall G, Moro J and Dickinson G 
(2022) An integrated assessment of the horticulture sector in northern Australia to inform 
future development. Sustainability (Switzerland) 14(18), 1–18. DOI: 10.3390/su141811647. 

Schipp G, Humphrey JD, Bosmans J and Northern Territory Department of Primary Industry, 
Fisheries and Mines (2007) Northern Territory barramundi farming handbook. Northern 
Territory Department of Primary Industry, Fisheries and Mines, Darwin. 

Southern Gulf NRM (2016). Land condition guide. Southern Gulf NRM, Mount Isa. 

Thomas M, Gregory L, Harms B, Hill JV, Holmes K, Morrison D, Philip S, Searle R, Smolinski H, Van 
Gool D, Watson I, Wilson PL and Wilson PR (2018) Land suitability analysis. A technical report 
from the CSIRO Northern Australia Water Resource Assessment to the Government of 
Australia. CSIRO, Canberra. 

Thomas M, Philip S, Zund P, Stockmann U, Hill J, Gregory L, Watson I and Thomas E (2024) Soils 
and land suitability for the Southern Gulf catchments. A technical report from the CSIRO 
Southern Gulf Water Resource Assessment for the National Water Grid. CSIRO, Australia. 

Watson I, Austin J and Ibrahimi T (2021) Other potential users of water. In: Petheram C, Read A, 
Hughes J, Marvanek S, Stokes C, Kim S, Philip S, Peake A, Podger G, Devlin K, Hayward J, 
Bartley R, Vanderbyl T, Wilson P, Pena Arancibia J, Stratford D, Watson I, Austin J, Yang A, 
Barber M, Ibrahimi T, Rogers L, Kuhnert P, Wang B, Potter N, Baynes F, Ng S, Cousins A, Jarvis 
D and Chilcott C (eds) An assessment of contemporary variations of the Bradfield Scheme. A 
technical report to the National Water Grid Authority from the Bradfield Scheme 
Assessment. CSIRO, Australia, chapter 8. 

Webster A, Jarvis D, Jalilov S, Philip S, Oliver Y, Watson I, Rhebergen T, Bruce C, Prestwidge D, 
McFallan S, Curnock M and Stokes C (2024) Financial and socio-economic viability of 
irrigated agricultural development in the Southern Gulf catchments. A technical report from 
the CSIRO Southern Gulf Water Resource Assessment for the National Water Grid. CSIRO, 
Australia. 

Woodward E, Jarvis D and Maclean K (2019) The traditional owner-led bush products sector: an 
overview scoping study and literature review. CSIRO, Australia. 

Yang A, Petheram C, Marvanek S, Baynes F, Rogers L, Ponce Reyes R, Zund P, Seo L, Hughes J, 
Gibbs M, Wilson PR, Philip S and Barber M (2024) Assessment of surface water storage 
options in the Victoria and Southern Gulf catchments. A technical report from the CSIRO 
Victoria River and Southern Gulf Water Resource Assessments for the National Water Grid. 
CSIRO Australia 


Yeates SJ (2001) Cotton research and development issues in northern Australia: a review and 
scoping study. Australian Cotton Cooperative Research Centre, Darwin. 

Yeates SJ and Poulton PL (2019) Determining dryland cotton yield potential in the NT: Preliminary 
climate assessment and yield simulation. Report to NT Farmers, Queensland Cotton and the 
Cotton Research and Development Corporation. CSIRO, Canberra. 

Yeates SJ, Strickland GR and Grundy PR (2013) Can sustainable cotton production systems be 
developed for tropical northern Australia? Crop and Pasture Science 64, 1127–1140. DOI: 
10.1071/CP13220. 


5 Opportunities for water resource development in 
the Southern Gulf catchments 

Authors: Matt Gibbs, Andrew R Taylor, Cuan Petheram, Ang Yang, Steve Marvanek, Lee Rogers, 
Fred Baynes, Geoff Hodgson, Justin Hughes, Anthony Knapton 

 
Chapter 5 examines the opportunities, risks and costs for water resource development in the 
catchments of the Southern Gulf rivers, that is Settlement Creek, Gregory–Nicholson River and 
Leichhardt River, the Morning Inlet catchments and the Wellesley island groupsFigure 5-1. 
1. Evaluating the 
possibilities for water resource development and irrigated agriculture requires an understanding 
of the development-related infrastructure requirements, how much water can be supplied and at 
what reliability, and the associated costs. The key components and concepts of Chapter 5 are 
shown in 

1 Only those islands greater than 1000 ha are mapped. 

 


Figure 5-1 Schematic of key engineering and agricultural components to be considered in the establishment of a 
water resource and greenfield irrigation development 

Numbers in blue refer to sections in this report. 


5.1 Summary 

This chapter provides information on a variety of potential options to supply water, primarily for 
irrigated agriculture. The methods used to generate these involved collating and synthesising 
existing data. No fieldwork was undertaken as part of this Assessment. The potential water yields 
reported in this chapter are based largely on physically plausible volumes, and do not consider 
economic, social, environmental, legislative or regulatory factors, which will inevitably constrain 
many developments. In some instances, the water yields are combined with land suitability 
information from Chapter 4 to provide estimates of areas of land that could potentially be 
irrigated close to the water source or storage. 

5.1.1 Key findings 

Water can be sourced and stored for irrigation in the Southern Gulf catchments in a variety of 
ways. If the water resources of the Southern Gulf catchments are developed for consumptive 
purposes it is likely that some of the options below may help to maximise the cost effectiveness of 
water supply in different parts of the study area. 

Groundwater extraction 

Groundwater is already widely used in parts of the Southern Gulf catchments for a variety of 
purposes (stock, domestic activities, mining, irrigation, community water supplies) and offers year-
round niche opportunities that are geographically distinct from surface water development 
opportunities. The two most productive groundwater systems in the catchments are the regional-
scale Cambrian Limestone Aquifer (CLA) and Gilbert River Aquifer (GRA). Currently, existing annual 
licensed groundwater entitlements for both aquifers are small. These are 1.8 GL/year for the CLA 
and <0.25 GL/year for the GRA, neither aquifers are currently used for groundwater-based 
irrigation. Across different parts of the catchments small amounts of unlicensed groundwater use 
for stock and domestic purposes also occurs from both aquifers. Water plans exist for both 
aquifers in the Queensland portion of the study area. The Gulf Water Plan manages groundwater 
resources of the CLA, and the groundwater resources of the GRA are managed under the Great 
Artesian Basin and Other Regional Aquifers water plan. There are currently no water plans for the 
NT parts of the catchments, where (of the two regional-scale aquifers) only the CLA exists. 

With appropriately sited borefields it may be possible to extract between 10 and 20 GL/year from 
the CLA in the south-west of the study area. This is where the aquifer outcrops to the west of 
where the reaches of Lawn Hill Creek and the Gregory and O'Shannassy rivers receive 
groundwater discharge from the CLA. This indicative scale of the resource is based on an initial 
estimate of the components of the water balance for the portion of the CLA underlying these 
catchments, as well as their potential sensitivity to climate variability. However, data for the CLA is 
sparse, and a more refined estimate of the scale of potential future groundwater resource 
development would require more detailed investigations of the water balance. Any potential 
development would also depend on potential impacts to groundwater-dependent ecosystems 
(GDEs), such as the prescribed reaches of Lawn Hill Creek and the Gregory River, to existing 
groundwater users (see Section 3.3.4), and community and government acceptance these 
changes. 


The GRA may also offer some opportunities for future groundwater resource development, 
though the aquifer in the north-east of the catchment is deep (>500 metres below ground level 
(mBGL)) in places and exhibits variable water quality not always suitable for irrigation. It may be 
possible with appropriately sited borefields to extract about 5 GL/year near the south-western 
margin of the GRA in the north-east of the catchments, where the aquifer is less than 500 m deep, 
and in places hosts fresh water (<1000 mg/L total dissolved solids (TDS)). Similar to the CLA, the 
actual scale of potential future groundwater resource development would depend upon 
community and government acceptance of potential impacts to GDEs and existing groundwater 
users (e.g. active water licences for the communities of Burketown and Gununa). 

Opportunities for potential groundwater resource development from aquifers hosted in other 
hydrogeological units (Proterozoic igneous, metasedimentary and metamorphic rocks) is most 
likely to be limited to use for stock and domestic purposes, and occasional community water 
supply. Aquifers within the Cenozoic alluvium may provide a source of water, though few data 
exists for these systems. 

Major dams 

Indigenous customary residential and economic sites are usually concentrated along major 
watercourses and drainage lines. Consequently, potential instream dams are more likely to have 
an impact on areas of high cultural significance than are most other infrastructure developments 
of comparable size. 

Topographically and geologically, large parts of the Southern Gulf catchments have considerable 
potential for large instream dams, and there are already five large water supply dams in the 
Southern Gulf catchments with capacities of about 10 GL or greater. These dams are used to 
supply water for mining, industry and the city of Mount Isa. These users typically use considerably 
less water than the amounts required for irrigated agriculture. In the Southern Gulf catchments a 
limitation of large dams is the semi-arid climate and typically small catchment areas of those parts 
of the catchment with suitable topography. This means that most potential sites for dams in the 
Southern Gulf catchments have relatively low yields (typically less than 100 GL in 85% of years). 

One of the most cost-effective potential large instream dam sites in the Southern Gulf catchments 
is on the Gregory River, immediately upstream of a large contiguous area (1.03 million ha) of soil 
suitable for irrigated agriculture. However, the site sits within the Thorntonia Aggregation 
wetland. A previous study found that residents at Mount Isa placed a particularly high value on the 
Gregory Rivers (Jackson et al., 2008). Considering existing consumptive users this potential dam 
could yield 133 GL in 85% of years and cost $683 million (−20% to +50%) to construct, assuming 
favourable geological conditions. With the land adjacent to the east bank of the Gregory River 
sloping away from the river, the land is highly suitable for the more cost-effective gravity channel 
reticulation infrastructure. A nominal reticulation scheme for 10,000 ha of irrigated land was 
estimated to cost an additional $31.8 million or $3180/ha (excluding farm development and 
infrastructure). 

Water harvesting and offstream storage 

Water harvesting, where water is pumped from a major river into an offstream storage such as a 
ringtank, is a cost-effective option for capturing and storing water from the Nicholson, Gregory 
and Leichhardt rivers. Approximately 21% of the study area (1,672,000 ha) was modelled as having 














soil and topography likely or possibly suitable for ringtanks, which is a large percentage relative to 
other catchments across northern Australia. The most favourable soil and topography for 
ringtanks in the study area is on the east bank of the Gregory River, where the extensive cracking 
clay soils of the Armraynald Plain gently slope away from the river, enabling the cost-effective 
conveyance of water using gravity. Water harvesting along the Nicholson is limited by the lack of 
soil suitable for the construction of off-stream storages. Downstream of Kajabbi the construction 
of ringtanks adjacent to the Leichhardt River is possible on heavier alluvial soils where the sandy 
levees are not so wide that the conveyance of water from the river to the ringtank would be 
prohibitively expensive. From the Nicholson and Leichhardt catchments it is physically possible to 
extract 150 GL in 75% of years and irrigate 12,000 ha of broadacre by pumping or diverting water 
from the Nicholson, Gregory and Leichhardt rivers and storing it in offstream storages such as 
ringtanks. This results in modelled reductions in mean and median annual discharge from the 
Gregory– Nicholson and Leichhardt rivers to the Gulf of Carpentaria of about 3% and 5%, 
respectively. 
Managed aquifer recharge 
The most promising aquifers for infiltration-based MAR in the Southern Gulf catchments are 
aquifers within the Cenozoic alluvium associated with many of the rivers in the study area. 
Visually the Cenozoic alluvium appears to be extensive relative to alluvium associated with many 
rivers elsewhere in northern Australia. However, bore logs and water-level information are not 
available for Cenozoic alluvium, and it is likely that the opportunity for MAR may vary between 
locations. Approximately 122,700 ha (1.1% of the study area) of the Southern Gulf catchments 
was identified as having potential for aquifers, groundwater and landscape characteristics 
suitable for infiltration MAR techniques within 5 km of a source of surface water – defined here 
as being a river with median annual flow greater than 20 GL. Approximately 37,100 ha (0.3% of 
the study area) within 1 km of such a river had similarly suitable characteristics; however, 94% of 
this area is underlain by Cenozoic alluvium. 
There may be potential to use MAR in the CLA to offset the impacts of groundwater pumping on 
GDEs near Lawn Hill Creek and the Gregory River. However, this would be contingent on finding 
soils suitable for the construction of ringtanks (Section 5.4.4), to temporarily detain surface 
water, close to a location that is suitable for MAR (typically on highly permeable soils). 
Gully dams and weirs 
Suitably sited large farm-scale gully dams are a relatively cost-effective method of supplying 
water. Those areas that are more topographically suitable for large-scale gully dam sites generally 
do not coincide with areas that have soils suitable for their construction or suitable for irrigated 
agriculture. There are, however, some locations in the north-west of Doomadgee in the 
Settlement Creek catchment and Mornington Island where there is some topography suitable for 
gully dams, soil suitable for their construction and versatile agricultural land nearby. These areas 
are geographically distinct from those areas that are most suitable for water harvesting and 
ringtanks. 
The remaining sources of water and storage options, namely weirs and natural water bodies, are 
estimated to be capable of reliably supplying considerably smaller volumes of water than major 


instream dams. Sourcing water from natural water bodies, although the most cost-effective 
option, is highly contentious. 

Summary of investigation costs, capital, and operation and maintenance costs of different 
water supply options and potential scale of unconstrained development 

Table 5-1 provides a summary of indicative investigative, capital, and operation and maintenance 
costs of different water supply options and estimates of the potential scale of unconstrained 
development. The development of any of these options will have an impact on existing uses, 
including ecological systems, to varying degrees, and will depend on the level of development. 
Ecological implications of altered flow regimes are examined in Section 7.3. All of the water source 
options reported in Table 5-1 are considerably cheaper than the cost of desalinisation. The initial 
cost of constructing four large desalinisation plants (capacity of 90 to 150 GL/year) in Australia 
between 2010 and 2012 ranged from $19,000/ML to $31,000/ML (AWA, 2018), indexed to 2023. 
This does not include the cost of ongoing operation (e.g. energy) and maintenance or the cost of 
conveying water to the demand. 

Table 5-1 Summary of capital costs, yields and costs per ML supply, including operation and maintenance 

Costs and yields are indicative. Values are rounded. Capital costs are the cost of construction of the water 
storage/source infrastructure. They do not include the cost of constructing associated infrastructure for conveying 
water or irrigation development. Water supply options are not independent of one another, and the maximum yields 
and areas of irrigation cannot be added together. Equivalent annual cost assumes a 7% discount rate over the service 
life of the infrastructure. Total yields and areas are indicative and based on physical plausibility unconstrained by 
economic, social, environmental, legislative or regulatory factors, which will inevitably constrain many developments. 

WATER SOURCE/STORAGE 

GROUND-
WATER† 

MANAGED 
AQUIFER 
RECHARGE‡ 

MAJOR DAM 

WEIR§ 

LARGE FARM-
SCALE 
RINGTANK 

LARGE FARM-
SCALE GULLY 
DAM 

NATURAL 
WATER 
BODY 

Cost and service life of individual representative unit 











Capital cost ($ million) 

4.5 

1.1 

680 

5–40 

2.5 

1.7 

0.02 

Operation and maintenance 
($ million/y)* 

0.1 

0.07 

2.7 



0.1–0.8 

0.125 

0.045 

~0 

Assumed service life (y) 

50 

50 

100 

50 

40 

30 

10 

Potential yield of individual representative unit at water source 









Yield at source (GL)†† 

2 

0.6 

133 

0.5–10 

2.4 

3 

0.125–0.5 

Unit cost ($/ML)‡‡ 

2,250 

1,830 

5,110 

6,500 

1,040 

570 

100 

Levelised cost 
($ million/ML) §§

215 

250 

380 

600 

130 

60 

10 

Potential yield of individual representative unit at paddock 









Assumed conveyance 
efficiency to paddock 
(%)††† 

95 

90 

75 

80 

90 

90 

90 

Yield at paddock (GL) 

1.9 

0.54 

100 

0.4–8 

2.2 

2.7 

0.11–0.45 

Unit cost ($/ML)‡‡ 

2,370 

2,040 

8,115 

8,125 

1,160 

630 

110 

Levelised cost 
($ million/ML) ††† 

225 

280 

600 

750 

145 

65 

12 




WATER SOURCE/STORAGE 

GROUND-
WATER† 

MANAGED 
AQUIFER 
RECHARGE‡ 

MAJOR DAM 

WEIR§ 

LARGE FARM-
SCALE 
RINGTANK 

LARGE FARM-
SCALE GULLY 
DAM 

NATURAL 
WATER 
BODY 

Total potential yield and area (unconstrained) 

 

 

 

 

 

 

Total potential yield (GL/y) 
at source ≥75% 
reliability‡‡‡ 

30 

<30 

320 

<100 

90 

<100 

<20 

Potential area that could be 
irrigated at ≥75% reliability 
(ha)§§§ 

4,500 

<4,500 

30,000 

<10,000 

12,000 

<10,000 

<2,000 



†Value assumes extraction from Cambrian Limestone Aquifer assuming mean bore yield of 25 L/s irrigation of 250 ha to meet mean peak 
evaporative demand over a 3-day period. Assumes a mean depth of 80 m and a drilling failure rate of 50%. 
‡Based on recharge weir. 
§Sheet piling weir. 
*Operation and maintenance (O&M) cost is the annual cost of operating and maintaining infrastructure and includes cost of pumping groundwater 
assuming groundwater is 10–20 m below ground level and the cost of pumping water into ringtank. 
††Yield at dam wall (taking into consideration net evaporation from surface water storages prior to release) or at groundwater bore. Value assumes 
large farm-scale ringtanks do not store water past August. 
‡‡Capital cost divided by the yield. 
§§Equivalent annual cost of storage per bore per ML of yield of water. Includes capital cost and O&M costs. Assumes 7% discount rate. 
†††Conveyance efficiency between dam wall/groundwater bore and edge of paddock (does not include field application losses). 
‡‡‡Actual yield will depend upon government and community acceptance of impacts to water-dependent ecosystems and existing users. Yields are 
not additive. Likely maximum cumulative yield at the dam wall/groundwater bore. Potential yield of major dams based on yield of dams at 
Waterhouse River. 
§§§Likely maximum area that could be irrigated (after conveyance and field application losses) in at least 75% of years. Assumes a single crop. Areas 
provided for each water source are not independent and hence are not additive. Actual area will depend upon government and community 
acceptance of impacts to water-dependent ecosystems and existing users. 

5.2 Introduction 

5.2.1 Contextual information 

Irrigation during the dry season and other periods when soil water is insufficient for crop growth 
requires sourcing water from a suitable aquifer or from a surface water body. However, decisions 
regarding groundwater extraction, river regulation and water storage are complex, and the 
consequences of decisions can be inter-generational, where even relatively small inappropriate 
releases of water may preclude the development of other, more appropriate (and possibly larger) 
developments in the future. Consequently, governments and communities benefit by having a 
wide range of reliable information available prior to making decisions, including the manner of 
ways water can be sourced and stored, as this can have long-lasting benefits and facilitate an open 
and transparent debate. 

Information is presented in a manner to easily enable the comparison of the variety of options. 
More detailed information can be found in the companion technical reports. Section 5.5 discusses 
the conveyance of water from the storage and its application to the crop. Transmission and field 
application efficiencies, and associated costs and considerations, are examined. 

All costs presented in this chapter are indexed to December 2023. 


Concepts 

The following concepts are used in sections 5.3 and 5.4: 

• Each of the water source and storage sections are structured around: (i) an opportunity- or 
reconnaissance-level assessment and (ii) a pre-feasibility-level assessment: 
– Opportunity-level assessments involved a review of the existing literature and a high-level 
desktop assessment using methods and datasets that could be consistently applied across the 
entire Assessment area. The purpose of an opportunity-level assessment is to provide a 
general indication of the likely scale of opportunity and geographic location of each option. 
– Pre-feasibility-level assessments involved a more detailed desktop assessment of 
sites/geographic locations that were considered more promising. This involved a broader and 
more detailed analysis including the development of bespoke numerical models, site-specific 
cost estimates and site visits. Considerable field investigations were undertaken for the 
assessment of groundwater development opportunities (Section 5.3.2). 



• ‘Yield’ is a term used to report the performance of a water source or storage. It is the amount of 
water that can be supplied for consumptive use at a given reliability. For dams, an increase in 
water yield results in a decrease in reliability. For groundwater, an increase in water yield results 
in an increase in the ‘zone of influence’ and can result in a decrease in reliability over time, 
particularly in local- and intermediate-scale groundwater systems. 
• Unit cost is the capital cost of the infrastructure divided by the amount of water that can be 
supplied at a specified reliability. It is commonly used to provide a comparison of the cost 
effectiveness of assets of similar life spans and operational costs. 
• Equivalent annual cost is the annual cost of owning, operating and maintaining an asset over its 
entire life. Equivalent annual cost allows a comparison of the cost effectiveness of various assets 
that have unequal service lives/life spans. 
• Levelised cost is the equivalent annual cost divided by the amount of water that can be supplied 
at a specified reliability. It allows a comparison of the cost effectiveness of various assets that 
have unequal service lives/life spans and water supply potential. 


Other economic concepts reported in this chapter, such as discount rates, are outlined in 
Chapter 6. 

5.3 Groundwater and subsurface water storage opportunities 

5.3.1 Introduction 

Groundwater, where an aquifer is relatively shallow (less than a couple of hundred metres) and of 
sufficient yield to support irrigation (typically greater than 10 L/s), is often one of the cheapest 
sources of water available, particularly where individual bore yields can be in the order of tens of 
litres per second thereby reducing the costs of groundwater infrastructure. 

Even the cheapest forms of MAR, infiltration-based techniques, are usually considerably more 
expensive than developing a groundwater resource. Further to this, in northern Australia many 
unconfined aquifers, which are best suited to infiltration-based MAR, either have large areas with 
no ‘free’ storage capacity at the end of the wet season (because groundwater levels have risen to 


near the ground surface) or, where they do have the available storage capacity, are often not at 
economically viable distances (greater than 5 km) from a reliable source of water to recharge the 
aquifer. Therefore, MAR will inevitably only be developed following development of a 
groundwater system, where groundwater extraction may create additional storage capacity within 
the aquifer (by lowering groundwater levels) to allow additional recharge, and hydrogeological 
information is more readily available to evaluate the local potential of MAR. However, if 
developed, MAR can increase the quantity of water available for extraction and help mitigate 
impacts to the environment. 

Where water uses have a higher value than irrigation (e.g. in mining, energy operations, town 
water supply), other more expensive but versatile forms of MAR, such as aquifer storage and 
recovery, can be economically viable and should be considered. 

The Assessment involved a catchment-wide reconnaissance assessment of: 

• the potential for groundwater resource development (Section 5.3.2) 
• MAR (Section 5.3.3). 


5.3.2 Opportunities for groundwater development 

Introduction 

Planning future groundwater resource developments and authorising licensed groundwater 
entitlements require value judgments of what is an acceptable impact to receptors such as 
environmental assets or existing users at a given location. These decisions can be complex, and 
they typically require considerable input from a wide range of stakeholders, particularly scientific 
information, to help inform these decisions, which include: 

• identifying aquifers that may be potentially suitable for future groundwater resource 
development 
• characterising their depth, spatial extent, saturated thickness, hydraulic properties and water 
quality 
• conceptualising the nature of their flow systems 
• estimating aquifer water balances 
• identifying geographical opportunities within key aquifers and the associated risks for future 
groundwater development. 


Opportunities include the identification and location of hydrogeological units and the aquifers 
they host. Risks include the potential to changes in aquifer storage and therefore reliability of 
access to water for existing users or the environment (groundwater-dependent ecosystems, 
GDEs). Unless stated otherwise, the material presented in Section 5.3.2 has been summarised 
from the companion technical report on groundwater characterisation (Raiber et al., 2024) and 
the companion technical report on groundwater modelling (Knapton et al., 2024). 

Opportunity-level assessment of groundwater resource development opportunities in the 
Southern Gulf catchments 

The hydrogeological units of the Southern Gulf catchments (Figure 5-2) contain a variety of local-, 
intermediate- and regional-scale aquifers that host localised to regional-scale groundwater flow 


systems. The regional-scale CLA and regional-scale GRA are present in the subsurface across large 
areas, collectively occurring beneath about 45% of the study area. Given their large spatial extent, 
they also underlie and frequently coincide with larger areas of soil suitable for irrigated agriculture 
(Section 4.2). They contain fresh water (<1000 mg/L TDS) in places and can yield water at a 
sufficient rate to support irrigation development (>10 L/s). These aquifers also contain larger 
volumes of groundwater in storage (gigalitres to teralitres) than local-scale aquifers and their 
storage and discharge characteristics are often less affected by short-term (yearly) variations in 
recharge rates caused by inter-annual variability in rainfall. Furthermore, their larger spatial extent 
provides greater opportunities for groundwater resource development away from existing water 
users and GDEs at the land surface such as springs, spring-fed vegetation and surface water, which 
can be ecologically and culturally significant. In contrast, local-scale aquifers in the Southern Gulf 
catchments, such as fractured and weathered rock and alluvial aquifers, host local-scale 
groundwater systems that are highly variable in composition, salinity and yield. They also have a 
small and variable spatial extent and less storage compared to the larger aquifers, limiting 
groundwater resource development to localised opportunities such as for stock and domestic use, 
or as a conjunctive water resource (i.e. combined use of surface water, groundwater or rainwater). 

The Assessment identified five hydrogeological units hosting aquifers that may have potential for 
future groundwater resource development in the Southern Gulf catchments (Table 5-2): 

•Cambrian limestone and dolostone
•Cretaceous rocks
•Cenozoic alluvium
•Proterozoic igneous rocks
•Proterozoic metasedimentary and metamorphic rocks.


Table 5-2 Opportunity-level estimates of the potential scale of groundwater resource development opportunities in 
the Southern Gulf catchments 

For locations of the hydrogeological units see Figure 5-2. The indicative scale of the groundwater resource is based on 
the magnitude of the inputs and outputs of the groundwater balance. The actual scale will depend upon potential 
impacts to groundwater-dependent ecosystems and existing groundwater users, and government and community 
acceptance of these changes. 

For more information on this table please contact CSIRO on enquiries@csiro.au

For more information on this table please contact CSIRO on enquiries@csiro.au
†Actual scale will depend upon government and community acceptance of impacts to groundwater-dependent ecosystems and existing water users. 


 

Figure 5-2 Hydrogeological units with potential for future groundwater resource development 

Presents the spatial extent of the outcropping and subcropping component of each hydrogeological unit with the 
majority of the Cenozoic cover removed (except the alluvium). Entire spatial extent of the Cambrian limestone and 
dolostone, and Cretaceous rocks outside the Southern Gulf catchments is shown in Figure 2-28. 

 

Simplified regional hydrogeology and springs map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\11_Groundwater\4_S_Gulf\1_GIS\1_Map_docs\Gr-S-515_simplified_regional_hydrogeology_CR.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au

Groundwater development costs 

The cost of groundwater development is the cost of the infrastructure plus the cost of the 
hydrogeological investigations required to understand the resource and risks associated with its 
development. 

This section presents information relevant to the cost of further developing the groundwater 
resources of the CLA, including but not limited to the depth to water-bearing formation (control 
over cost of drilling) and the depth to groundwater (control over cost of pumping). Information on 
the spatial extent of drawdown of groundwater levels is also presented. This is relevant to the 
potential hydraulic impact of future development on receptors such as existing licensed water 
users and culturally and ecologically important GDEs. Aquifer yield information is presented in 
Section 2.5.2. 

At a local development scale, individual proponents will need to undertake sufficient localised 
investigations to provide confidence around aquifer properties and bore performance. This 
information will also form part of an on-site hydrogeological assessment required by the regulator 
in order to grant an authorisation to extract groundwater. Key considerations for an individual 
proponent include: 

• determining the location to drill a production bore 
• testing the production bore 
• determining the location and number of monitoring bores required 
• conducting a hydrogeological assessment as part of applying for an authorisation to extract 
groundwater. 


Estimates of costs associated with these local-scale investigations are summarised in Table 5-3. 

Table 5-3 Summary of estimated costs for a 250 ha irrigation development using groundwater 

Assumes mean bore yield of 25 L/s and with 16 production bores required to meet peak evaporative demands of 
250 ha. Does not include operating and maintenance costs. 

DRILLING, CONSTRUCTION, INSTALLATION AND TESTING OF BORES 

ESTIMATED COST ($) 

Production bore 

2,550,000† 

Monitoring bores 

285,000‡ 

Submersible pumps 

1,360,000§ 

Mobilisation/demobilisation 

6,000§§ 

Aquifer testing 

170,000* 

Hydrogeological assessment 

100,000†† 



†Value assumes 16 production bores drilled and constructed at a mean depth of 60 m at a cost per bore of $750/m, constructed with 200 mm steel 
casing at a cost of $82/m and 18 m stainless steel wire-wound screen at a cost of $150/m. Assumes on average two holes need to be drilled for 
every cased production bore. 
‡Value assumes six PVC monitoring bores drilled and constructed at a mean depth of 60 m at a cost of $500/m, constructed with 150 mm PVC and 
5 m machine-slotted screen at a cost of $50/m. 
§Value assumes a pump that is rated to draw water at a rate of up to 60 L/s, as well as rated to draw water from depths of up to 50 mBGL. Value 
based on 16 pumps. 
§§Value assumes a mobilisation/demobilisation rate of $10/km from Darwin to Daly Waters and return (approximately 1200 km round trip). 
*Value assumes six 72-hour aquifer tests (48 hours pumping, 24 hours recovery) at a cost of $500/h and $4000 mobilisation/demobilisation. 
††Indicative cost to proponent. Value assumes a small-scale development away from existing users and groundwater-dependent ecosystems. 
Assumes the regulator has already characterised the aquifers at the intermediate/regional scale to better understand the resource potential under 
cumulative extraction scenarios, as well as current and future constraints to development. 


The Assessment identified the CLA to be the most promising intermediate- and regional-scale 
aquifer, with potential for future groundwater resource development in the Southern Gulf 
catchments. The CLA coincides with large, contiguous areas of cracking clay soils suitable for 
irrigated broadacre cropping (308,000 ha) along the south-western margin of the study area 
(Section 2.3). However, as discussed in Section 2.5.4, groundwater discharge from the CLA 
provides the dry-season flow in Lawn Hill Creek, and the Gregory and O’Shannassy rivers and some 
of their tributaries. 

The parts of the CLA in the south-western part of the Southern Gulf catchments appear to offer 
some promising opportunities for potential future groundwater resource development but require 
further investigation. The aquifer outcrops, subcrops and is mostly unconfined in the south-west 
of the Southern Gulf catchments (Figure 5-2 and Figure 5-5). This means it outcrops at the surface, 
or is close to the surface (within tens of metres of it) and is directly recharged by outcrop areas or 
by infiltration of rainfall through either low-permeability black clay soils or by vertical leakage 
through the overlying Cambrian siltstone where it is present across the southern part of the 
aquifer (Figure 5-2). 

The Georgina Basin, which hosts several hydrogeological units (Camooweal Dolostone, Thorntonia 
Limestone and Wonarah Formation) that collectively host the CLA, ranges in thickness from less 
than 100 m along the eastern/south-eastern basin margins to about 1000 m along the south-
western boundary of the Southern Gulf catchments (Figure 5-4). 

 

Figure 5-3 Groundwater dependent ecosystems along Lawn Hill Creek 

Photo: Auscape/Universal Images Group via Getty Images 



 

Figure 5-4 Thickness of the Georgina Basin in the Southern Gulf catchments 

Only a partial spatial extent of the Georgina Basin is shown beyond the Southern Gulf catchments boundary. Depths 
are in metres. 

Georgina Basin extent data source: Raymond (2018) 

The CLA occurs within the top few hundred metres of the Georgina Basin and varies in thickness 
from about 50 m along the eastern margin to about 500 m towards the catchment’s boundary 
(Figure 5-4 and Figure 5-5). At Carrara 1 (deep stratigraphic drill-hole), the CLA is about 500 m 
thick (Figure 5-4 and Figure 5-5). 

Thickness of Georgina Basin, map
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For more information on this figure please contact CSIRO on enquiries@csiro.au

 

Figure 5-5 Hydrogeological cross-section through the Cambrian Limestone Aquifer in the Georgina Basin and south-
west of the Southern Gulf catchments 

See Figure 5-4 for the spatial location of the eastern part of the cross-section. AHD = Australian Height Datum. 

While the current level of knowledge for the aquifer is considered low to medium, the following 
information indicates the aquifer offers potential for future development: 

• The moderate spatial extent of the outcropping/subcropping area in the catchment (about 
12,400 km2, see Figure 5-2) coincides with areas of cracking clay soils potentially suitable for 
agricultural intensification (Section 2.3.2). 
• The aquifer can be intersected by drilling at relatively shallow depths in the outcropping and 
subcropping areas (mostly <100 mBGL). 
• Moderate bore yields (up to 20 L/s) indicate that the aquifer may have potential to yield water 
at a sufficient rate for groundwater-based irrigation. 
• The depth to pump groundwater to the surface is less than 75 mBGL across most areas of the 
CLA, though groundwater-level data are sparse, and larger areas of shallow depths to 
groundwater (<10 mBGL) are likely to occur around the middle to lower reaches of the 
prescribed watercourses of Lawn Hill Creek, and the Gregory and O’Shannassy rivers, where the 
aquifer discharges (Figure 5-6). 
• The aquifer host fresh water suitable for a variety of irrigated crops (mostly <1000 mg/L TDS). 


For more information on this figure please contact CSIRO on enquiries@csiro.au

 

Figure 5-6 Depth to standing water level (SWL) of the Cambrian Limestone Aquifer (CLA) 

Only a partial spatial extent of the CLA is shown beyond the Southern Gulf catchments boundary. Depths are in metres 
below the land surface. Lower left inset indicates the south-western part of the catchments where the mapped data 
are shown, as well as its location within the eastern part of the Georgina Basin (light purple). 

The Assessment undertook an extensive review of the hydrogeological data and information to 
confirm the conceptual model of the CLA in the eastern Georgina Basin. This conceptual model 
was used to develop an initial two-dimensional groundwater flow model for the CLA in the south-
western part of the Southern Gulf catchments (the Undilla Sub-basin in the eastern part of the 
Georgina Basin). The purpose of the model was to assess the nature and scale of the groundwater 
resources of the Undilla Sub-basin, which provides baseflow to parts of Lawn Hill Creek, and the 
Gregory and O’Shannassy rivers. Initial order of magnitude groundwater balance estimates were 
derived for the entire groundwater model domain, which extends south-west of the catchment 
boundaries, and also for the portions of the Lawn Hill Creek and Gregory River subcatchments, and 
Nicholson Groundwater Management Area (NGMA), that coincide with the CLA inside the 
Southern Gulf catchments (Figure 5-7). 

SWL CLA
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Figure 5-7 Location of the Undilla Sub-basin groundwater flow model in relation to the Southern Gulf catchments 
and portions of the model that coincide with the Lawn Hill Creek and Gregory subcatchments and Nicholson 
Groundwater Management Area 

Lower left inset indicates the south-western part of the catchments where the mapped data are shown, as well as its 
location within the eastern part of the Georgina Basin (light purple). GW = groundwater. 

Table 5-4 provides a summary of the mean annual groundwater balances for the 109-year climate 
sequence (1910–2019) presented for portions of the CLA that coincide with the Lawn Hill Creek 
and Gregory subcatchments, the NGMA and the entire model domain. Within the model domain 
the CLA coincides with 2344 km2 of the Lawn Hill subcatchment and 9727 km2 of the Gregory 
subcatchment. The CLA coincides with 10,266 km2 of the NGMA, whereas the entire model 
domain for the CLA is 50,867 km2, most of which extends to the south-west outside the 
catchments (Figure 5-7). When considering the magnitude in modelled recharge volumes by area, 
these equate to recharge rates of about 25 mm/year for the portion of the CLA in the Lawn Hill 
Creek subcatchment, 14 mm/year for the portion of the CLA in the Gregory subcatchment, 
15 mm/year for the portion of the CLA in the NGMA and 7 mm/year for the entire model domain. 

CLA GW flow model WAP, map
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Table 5-4 Mean annual groundwater balance for the Cambrian Limestone Aquifer (CLA) in the Undilla Sub-basin of 
the Georgina Basin for a 109-year climate sequence (1910–2019) and areas of the CLA that coincide with the Lawn 
Hill Creek and Gregory subcatchments and Nicholson Groundwater Management Area (NGMA) 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au 
Initial modelling of the mean annual groundwater balance for the CLA in the south-western 
Southern Gulf catchments suggests the aquifer potentially offers opportunities for groundwater 
resource development based on the magnitude of groundwater flows. However, the initial model 
has limitations due to the data-sparse nature of the CLA in this area, including a lack of (i) spatial 
and temporal groundwater-level data, (ii) gauging of spring flow at discrete springs and (iii) 
estimates of mean annual recharge using a variety of independent methods. In addition, recent 
modelling of the CLA by Knapton et al. (2023) highlighted the potential sensitivity of the CLA 
groundwater balance to climate variables. Based on mean annual recharge summarised in Table 
5-4, an indicate scale of the resource for the CLA in the Southern Gulf catchments is estimated to 
be between 10 and 20 GL. However, this required further investigation. In addition, the actual 
scale of development will depend upon government and community acceptance of potential 
impacts to groundwater-dependent ecosystems and existing groundwater users, as well as the 
approval of licenses to extract groundwater. 

Groundwater resource development opportunities and risks associated with the Gilbert River 
Aquifer 

The GRA within the Great Artesian Basin, despite being data sparse, appears to offer some 
opportunities for future groundwater resource development but requires further investigation. 
The GRA is a sandstone aquifer occurring beneath Cretaceous mudstone rocks in the north-west of 
the catchment and extends offshore out beneath the Gulf of Carpentaria (Figure 5-2). The depth 
to the top of the GRA beneath the mudstone rocks is shallowest (<150 mBGL) along the south-
west margin of the GRA running in a north-west to south-east orientation, from north of Hells 
Gate Roadhouse to Burke and Wills Roadhouse (Figure 5-8). Depth to the top of the GRA increases 
in the subsurface in a north-easterly direction towards the coastline where depths are generally 


between 400 and 500 mBGL (Figure 5-8 and Figure 5-9). The deepest parts of the GRA near the 
coastline occur around Burketown, where depth to the top of the GRA is between 500 and 
700 mBGL (Figure 5-8 and Figure 5-9). For example, the original Burketown community water 
supply bore intersected the top of the GRA at about 670 mBGL (Figure 5-8). 

 

Figure 5-8 Depth to the top of the Gilbert River Aquifer (GRA) 

This is a mapped spatial extent of the GRA both within and beyond the Southern Gulf catchments boundaries. Depths 
are in metres below the land surface. Stratigraphic data represent a bore with stratigraphic data to obtain information 
about changes in geology with depth. A to A′ represents the location of the cross-section in Figure 5-9. 

Georgina Basin extent data source: Raymond (2018) 

Depth to GRA, map
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In the Gulf of Carpentaria beneath Gununa, the depth to the top of the GRA is similar to that 
around Burketown (~500 to 700 mBGL). The original Gununa community water supply bore 
intersected the top of the GRA at about 700 mBGL (Figure 5-8). The Cretaceous mudstone rocks 
that overlie the GRA are an aquitard (rocks of low permeability that store and transmit little 
groundwater), which confines the GRA (sealing it off from the atmosphere and pressurising the 
groundwater it stores and transmits) and prevents recharge from entering the aquifer. The GRA is 
recharged to the east of the Southern Gulf catchments, east of Karumba and Normanton. The GRA 
in the Southern Gulf catchments receives its inflows from groundwater in the GRA to the east of 
the Southern Gulf catchments, which flows into the catchment from west to north-west. 

 

Figure 5-9 South-west to north-east cross-section traversing the Great Artesian Basin in the Southern Gulf 
catchments. 

See Figure 5-8 for the spatial location of the cross-section. AHD = Australian Height Datum. 

Changes in the depth to groundwater across the GRA vary from close to artesian (groundwater 
rises under natural pressure to the land surface) to artesian, though standing water level data for 
the aquifer are limited. The south-west margin of the GRA groundwater is close to artesian 
(<20 mBGL) (Figure 5-10). Further to the north-east, towards the coast, groundwater becomes 
artesian up to about 20 m above the land surface (Figure 5-10). The original Burketown water 
supply bore, drilled in the 1900s, had an artesian water level of about 40 m above the land surface 
and a flow rate of about 7 L/second. 

For more information on this figure please contact CSIRO on enquiries@csiro.au

 

Figure 5-10 Depth to standing water level of the Gilbert River Aquifer (GRA) 

Mapped spatial extent of the GRA both within and beyond the Southern Gulf catchments boundary. Positive values 
are depth above the land surface representing artesian conditions; negative values are depths below the land surface 
representing sub-artesian conditions. 

Aquifer extent data source: Raymond (2018) 

While the current level of knowledge for the GRA has limited pre-feasibility information, the 
following information indicates it offers potential for future development: (i) the large spatial 
extent of the aquifer in the subsurface (about 44,600 km2, or about 40% of the study area; see 
Figure 5-2) that coincides with soils potentially suitable for agricultural intensification (Section 
2.3.2); (ii) the aquifer can be intersected by drilling at depths of mostly less than <400 mBGL 
(Figure 5-8) along the south-western margin of the GRA in the north-east of the catchments, also 
an area where groundwater is mostly fresh (<1000 mg/L TDS); and (iii) the aquifer is either 
artesian or close to artesian, thereby reducing the costs of pumping the groundwater to the 
surface, though groundwater-level data are sparse (Figure 5-10). 

Currently, insufficient information exists to quantify the water balance for the GRA in the Southern 
Gulf catchments. Furthermore, the aquifer: (i) has sparse temporal water-level information; (ii) 

SWL of GRA, map
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dips steeply in the subsurface, indicating it shifts across different areas from semi-confined to 
confined conditions; and (iii) support active water licences for community water supplies at 
Burketown and Gununa, as well as potentially supporting ecologically and culturally important 
flora and fauna in the Gulf of Carpentaria’s marine environment through coastal and submarine 
groundwater discharge. In the absence of further hydrogeological investigations (drilling and 
pump testing) and hydrological risk assessment modelling to evaluate groundwater extraction 
impacts to existing water users and GDEs, a conservative value of ≤5 GL/year has been assumed 
for the indicative scale of the resource for potential groundwater resource development (Table 
5-2). However, this requires further investigation, and would depend upon government and 
community acceptance of potential impacts to groundwater-dependent ecosystems and existing 
groundwater users, as well as the approval of licenses to extract groundwater. 

Groundwater resource development opportunities and risks associated with aquifers hosted in 
other hydrogeological units 

Opportunities for potential groundwater resource development from aquifers hosted in other 
hydrogeological units (Proterozoic igneous, metasedimentary and metamorphic rocks) is most 
likely to be limited to use for stock and domestic purposes, and occasional community water 
supply. However, productive local-scale aquifers hosted in the Cenozoic alluvium occurring in 
patches associated with the streambed, stream channel and floodplain of parts of the Nicholson, 
Gregory and Leichhardt rivers and their tributaries may offer some opportunities but require 
further investigation. The largest occurrences of the alluvium occur in the north of the catchment 
along the middle to lower reaches of the Nicholson, Gregory and Leichhardt rivers (Figure 5-2). 
Indicative bore yield data indicate bore yields can be as high as 5 L/second, which is too low for 
commercial irrigated agriculture, but the aquifer is currently sparsely tested and yields are likely to 
be locally variable. Water quality can vary from fresh to brackish but also remains sparsely tested. 
However, in places the aquifers may offer potential for small-scale (<1 GL/y) localised 
developments or as a conjunctive water resource. Opportunities are likely to be limited where the 
alluvium is (i) storage-limited (thin saturated thickness <15 m), (ii) comprising mostly fine-textured 
sediments (clay lenses), (iii) regularly flooded and (iv) highly connected to perennial reaches of 
prescribed watercourses and development may impact water availability to GDEs. 

5.3.3 Managed aquifer recharge 

Introduction 

MAR is the intentional recharge of water to aquifers for subsequent recovery or environmental 
benefit (NRMMC-EPHC-NHMRC, 2009). Importantly for northern Australia, which has high intra-
annual variability in rainfall, MAR can contribute to planned conjunctive use, whereby excess 
surface water can be stored in an aquifer in the wet season for subsequent reuse in the dry season 
(Evans et al., 2013; Lennon et al., 2014). 

Individual MAR schemes are typically small- to intermediate-scale storages with annual extractable 
volumes of up to 20 GL/year. In Australia, they currently operate predominantly within the urban 
and industrial sectors, and in the agricultural sector. This scale of operation can sustain rural to 
urban centres, contribute to diversified supply options in large urban centres and provide localised 
water management options, and it is suited to mosaic-type irrigation developments. 


The basic requirements for a MAR scheme are the presence of a suitable aquifer for storage, 
availability of an excess water source for recharge and a demand for water. The presence of 
suitable aquifers is determined from previous regional-scale hydrogeological and surface 
geological mapping (see companion technical report on groundwater characterisation by Raiber et 
al., 2024)). Source water availability is considered in terms of presence/absence rather than 
volumes with respect to any existing water management plans. 

Pre-feasibility assessment was based on MAR scheme entry-level assessment in the Australian 
guidelines for water recycling: managed aquifer recharge (NRMMC-EPHC-NHMRC, 2009; referred 
to as the ‘MAR guidelines’). The MAR guidelines provide a framework to assess feasibility of MAR; 
they incorporate four stages of assessment and scheme development. The first stage is entry-level 
assessment (pre-feasibility), the second stage involves investigations and risk assessment, the 
third stage is MAR scheme construction and commissioning, and the fourth stage is operation of 
the scheme. 

There are numerous types of MAR (Figure 5-12) and the selection of MAR type is influenced by the 
characteristics of the aquifer, the thickness and depth of low-permeability layers, land availability 
and proximity to the recharge source. Infiltration techniques can be used to recharge unconfined 
aquifers, with water infiltrating through permeable sediments beneath a dam, river or basin. If 
infiltration is restricted by superficial clay, the recharge method may involve a pond or sump that 
penetrates the low-permeability layer. Bores are used to divert water into deep or confined 
aquifers. Infiltration techniques typically have a lower cost than bore injection (Dillon et al., 2009; 
Ross and Hasnain, 2018) and are generally favoured in this Assessment. The challenge in northern 
Australia is to identify a suitable unconfined aquifer with capacity to store more water when water 
is available for recharge. In the Southern Gulf catchments, suitable unconfined aquifers are 
typically thought to rapidly recharge to full capacity during the wet season. 

 

Figure 5-11 Uncontrolled artesian flow from the Gilbert River Aquifer at the Burketown groundwater bore 

Photo: Shutterstock – Cam Laird 

A small rock in a muddy area
Description automatically generated with medium confidence




Figure 5-12 Types of managed aquifer recharge 

ASR = aquifer storage and recovery; ASTR = aquifer storage, transfer and recovery. Groundwater level indicated by 
triangle. Arrows indicate nominal movement of water. 

Source: Adapted from NRMMC-EPHC-NHMRC (2009) 


Opportunity-level assessment of infiltration-based MAR in the Southern Gulf catchments 

The most promising aquifers for infiltration-based MAR in the Southern Gulf catchments are 
aquifers within the Cenozoic alluvium associated with many of the rivers in the study area. Visually 
the Cenozoic alluvium appears to be extensive relative to alluvium associated with many rivers 
elsewhere in northern Australia. However, bore logs and water-level information are not available 
for Cenozoic alluvium, and it is likely the opportunity for MAR may vary between locations. There 
may be potential to use MAR in the CLA to offset the impacts of groundwater pumping on GDE 
near Lawn Hill Creek and the Gregory River. However, this would be contingent on finding soils 
suitable for the construction of ringtanks (Section 5.4.4), to temporarily detain surface water, 
close to a location that is suitable for MAR (typically on highly permeable soils). 

Groundwater use lowers groundwater levels and therefore creates storage capacity in the aquifer, 
which is required for MAR. However, the challenge remains to target aquifers with storage 
capacity at the end of the wet season, or to identify an available recharge source near and when 
there is sufficient storage capacity (i.e. early in the dry season). Infiltration techniques recharging 
unconfined aquifers are generally favoured for producing cost-effective water supplies, hence the 
initial focus on recharge techniques and limitations for unconfined aquifers. 

MAR opportunity maps were developed from the best available data at the catchment scale using 
the method outlined in the Northern Australia Water Resource Assessment technical report on 
MAR (Vanderzalm et al., 2018). This method uses four suitability classes for the more promising 
aquifers for MAR: 

• Class 1 – highly permeable and low slope (<5%) 
• Class 2 – highly permeable and moderate slope (5% to 10%) 
• Class 3 – moderately permeable and low slope (<5%) 
• Class 4 – moderately permeable and moderate slope (5% to 10%). 


Class 1 is considered most suitable for MAR and Class 4 least suitable. All areas not classified into 
one of classes 1, 2, 3 and 4 are considered unsuitable. Figure 5-13 shows the suitability map for 
MAR in the Southern Gulf catchments, with classes 1 and 2 considered potentially suitable for 
MAR. The opportunity assessment (Figure 5-14) indicates approximately 480 km2 (0.5%) of the 
Southern Gulf catchments may have aquifers with potential for MAR within 5 km of a major 
drainage line (excluding the highly intermittent drainage lines on the Sturt Plateau). Approximately 
75 km2 (~0.1%) of the study area is considered Class 1 or Class 2 and is within 1 km2 of a major 
drainage line. 

Water-level data for monitoring bores across the Southern Gulf catchments provide some insight 
into the potential for aquifers to store additional water. A watertable level deeper than 4 m is 
recommended in order to have sufficient storage capacity for MAR. Sufficient aquifer storage 
space is indicated where depth to water is either greater than 4 m at the end of the wet season 
(i.e. available for recharge year round) or greater than 4 m at the end of the dry season (i.e. 
available for seasonal recharge). Bores recording depth to water of less than 4 m at the end of the 
dry season could be considered as indicative that no storage space exists at any time of year. No 
water-level data are available for the Quaternary alluvium aquifers (Figure 5-14) and have been 
used for MAR elsewhere in Australia. However, the opportunity to use these aquifers for MAR in 
the Southern Gulf catchments is unknown and may vary between locations. 




Figure 5-13 Managed aquifer recharge (MAR) opportunities for the Southern Gulf catchments independent of 
distance from a water source for recharge 

Analysis based on the permeability (Thomas et al., 2024) and terrain slope (Gallant et al., 2011) datasets and limited to 
the Cambrian Limestone and Cenozoic alluvium aquifers. 



MAR map
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The opportunity assessment (Figure 5-14) indicates approximately 122,700 ha (1.1%) of the 
Southern Gulf catchments may have aquifers (including areas of Quaternary alluvium) with 
potential for MAR within 5 km of drainage lines that have a median annual flow greater than 
20 GL. Approximately 37,100 ha (~0.3%) of the study area is considered Class 1 or Class 2 and is 
within 1 km of drainage lines and with a median annual flow greater than 20 GL. However, 94% of 
this latter area is underlain by Quaternary alluvium aquifers for which the storage capacity and 
water level are unknown. 

See the Northern Australia Water Resource Assessment technical report on MAR schemes in 
northern Australia (Vanderzalm et al., 2018) for detailed costings on ten hypothetical MAR 
schemes in northern Australia. 



Figure 5-14 (a) Managed aquifer recharge (MAR) opportunities in the Southern Gulf catchments within 5 km of 
major rivers and (b) aquifer underlying the MAR opportunity classes 

Analysis based on the permeability (Thomas et al., 2024) and terrain slope (Gallant et al., 2011) datasets and limited to 
the Cambrian Limestone and Cenozoic alluvium aquifers. 



5km major riv MAR map
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5.4 Surface water storage opportunities 

5.4.1 Introduction 

In a highly seasonal climate, such as that of the Southern Gulf catchments, and in the absence of 
suitable groundwater, surface water storages are essential to enable irrigation during the dry 
season and other periods when soil water is insufficient for crop growth. 

The Assessment undertook a pre-feasibility-level assessment of three types of surface water 
storage options. These were: 


•major dams that could potentially supply water to multiple properties (Section 5.4.2)
•re-regulating structures such as weirs (Section 5.4.3)
•large farm-scale or on-farm dams, which typically supply water to a single property (Section 
5.4.4 and Section 5.4.5).


Both major dams and large farm-scale dams can be further classified as instream or offstream 
water storages. In the Assessment, instream water storages are defined as structures that 
intercept a drainage line (creek or river) and are not supplemented with water from another 
drainage line. Offstream water storages are defined as structures that (i) do not intercept a 
drainage line or (ii) intercept a small drainage line and are largely supplemented with water 
extracted from a nearby larger drainage line. Ringtanks and turkey nest tanks are examples of 
offstream storages with a continuous embankment; the former is the focus in the Assessment due 
to their higher storage-to-excavation ratios, relative to the latter. 

The performance of a dam is often assessed in terms of water yield. This is the amount of water 
that can be supplied for consumptive use at a given reliability. For a given dam, an increase in 
water yield results in a decrease in reliability. 

Importantly, the Assessment does not seek to provide instruction on the design and construction 
of farm-scale water storages. Numerous books and online tools provide detailed information on 
nearly all facets of farm-scale water storage (e.g. IAA, 2007; Lewis, 2002; QWRC, 1984). Siting, 
design and construction of weirs, large farm-scale ringtanks and gully dams are heavily regulated 
in most jurisdictions across Australia and should always be undertaken in conjunction with a 
suitably qualified professional and tailored to the nuances that occur at every site. Major dams are 
complicated structures and usually involve a consortium of organisations and individuals. 

Unless otherwise stated, the material in Section 5.4 originates from the companion technical 
report on surface water storage (Yang et al., 2024). 

5.4.2 Major dams 

Introduction 

Major dams are usually constructed from earth, rock and/or concrete materials, and typically act 
as a barrier wall across a river to store water in the reservoir created. They need to be able to 
safely discharge the largest flood flows likely to enter the reservoir, and the structure has to be 
designed so that the dam meets its purpose, generally for at least 100 years. Some dams, such as 


the Kofini Dam in Greece and the Anfengtang Dam in China, have been in continuous operation for 
over 2000 years, with Schnitter (1994) consequently coining dams as ‘the useful pyramids’. 

An attraction of major dams over farm-scale dams is that if the reservoir is large enough relative to 
the demands on the dam (i.e. water supplied for consumptive use and ‘lost’ through evaporation 
and seepage), when the reservoir is full, water can last 2 or more years. This has the advantage of 
mitigating against years with low inflows to the reservoir. For this reason, major dams are 
sometimes referred to as ‘carry-over storages’. 

Major instream versus offstream dams 

Offstream water storages were among the first man-made water storages (Nace, 1972; 
Scarborough and Gallopin, 1991) because people initially lacked the capacity to build structures 
that could block rivers and withstand large flood events. One of the advantages of offstream 
storages is that, if properly designed, they can cause less disruption of the natural flow regime 
than large instream dams. Less disruption occurs if water is extracted from the river using pumps, 
or if there is a diversion structure with gates that can be raised, to allow water and aquatic species 
to pass through when not in use. In the very remote environments of northern Australia, the 
period in which these gates need to be operated is also the period in which it is difficult to move 
around wet roads and flooded waterways. 

The primary advantage of large instream dams is that they provide a very efficient way of 
intercepting the flow in a river, effectively trapping all flow until the full supply level (FSL) is 
reached. For this reason, however, they also provide a very effective barrier to the movement of 
fish and other species within a river system, alter downstream flow patterns and can inundate 
large areas of land upstream of the dam. 

Types of major dams 

Two types of major dams are particularly suited to northern Australia: embankment dams and 
concrete gravity dams. Embankment dams are usually the most economic, provided suitable 
construction materials can be found locally, and are best suited to smaller catchment areas where 
the spillway capacity requirement is small. Concrete gravity dams with a central overflow spillway 
are generally more suitable where a large-capacity spillway is needed to discharge flood inflows, 
as is the case in most large catchments in northern Australia. 

Traditionally, concrete gravity dams were constructed by placing conventional concrete in formed 
‘lifts’. Since construction of Kidston Dam (officially known as the Copperfield River Gorge Dam) in 
1984 in Australia, however, roller compacted concrete (RCC) has been used, where low-cement 
concrete is placed in continuous thin layers from bank to bank and compacted with vibrating 
rollers. This approach allows large dams to be constructed in a far shorter time frame than 
required for conventional concrete construction, often with large cost savings (Doherty, 1999). 
RCC is best used for high dams where a larger-scale plant can provide significant economies of 
scale. This is now the favoured type of construction in Australia whenever foundation rock is 
available within reasonable depth, and where a larger-capacity spillway is required. In those parts 
of the Southern Gulf catchments with topography and hydrology most suited to large instream 
dams, RCC was deemed to be the most appropriate type of dam. 


Opportunity-level assessment of potential major dams in the Southern Gulf catchments 

A promising dam site requires inflows of sufficient volume and frequency, topography that 
provides a constriction of the river channel and, critically, favourable foundation geology. With 
few studies of large dams in the Southern Gulf catchments identified, the opportunity-level 
assessment of potential major dams in the Southern Gulf catchments was undertaken using a 
spatial analysis approach. To ensure no potential dam site had been overlooked, the Assessment 
used a bespoke computer model, the DamSite model (Petheram et al., 2017), to assess over 
50 million sites in the Southern Gulf catchments for their potential as major offstream or instream 
dams. 

Broad-scale geological considerations 

The Southern Gulf catchments drain from the uplands in the south-west and south towards the 
north-east (referred to as the ‘uplands’), where the river systems cross a broad depositional plain 
several tens of kilometres wide (referred to as the Armraynald Plain) before emptying into the 
Gulf of Carpentaria. 

Favourable foundation conditions include a relatively shallow layer of unconsolidated materials, 
such as alluvium, and rock that is relatively strong, resistant to erosion, non-permeable or capable 
of being grouted. Geological features that make dam construction challenging include the 
presence of faults, weak geological units, landslides and deeply weathered zones. 

Potentially feasible large dam sites in the Southern Gulf catchments occur where resistant ridges 
of Proterozoic sandstone beds that have been incised by the river systems outcrop on both sides 
of river valleys. The sandstones are generally weathered to varying degrees and the depth of 
weathering and the amount of sandstone outcrop on the valley slopes is a fundamental control on 
the suitability of the potential dam sites. Where the sandstones are relatively unweathered and 
outcrop on the abutments of the potential dam site, less stripping will be required to achieve a 
satisfactory founding level for the dam. The other fundamental control on the suitability of the 
dam is the extent and depth of the Quaternary alluvial sands and gravels in the floor of the valley, 
as these materials will have to be removed to achieve a satisfactory founding level for the dam. 

In general, where stripping removes the more weathered rock, it is anticipated that the 
Proterozoic sandstones will form a reasonably watertight dam foundation requiring conventional 
grout curtains and foundation preparation. 

Where potentially soluble dolomites occur within the Proterozoic sequences (soluble over a 
geological timescale) then it is possible that potentially leaky dam abutments and reservoir rims 
may be present, requiring specialised and costly foundation treatment such as extensive grouting. 

Where rivers are tidal the presence of soft estuarine sediments has the potential to make dam 
design more challenging and construction more expensive, which may compromise the feasibility 
of a dam. 

Sites potentially topographically suitable for large storages for water supply 

Figure 5-15 displays the most promising sites across the Southern Gulf catchments in terms of 
topography, assessed in terms of approximate cost of construction per storage volume (ML). 
Favourable locations with a small catchment area and adjacent to a large river may be suitable as 
major offstream storages. 


 

Figure 5-15 Potential storage sites in the Southern Gulf catchments based on minimum cost per megalitre storage 
capacity 

This figure can be used to identify locations where topography is suitable for large offstream storages. At each 
location the minimum cost per megalitre storage capacity is displayed. The smaller the minimum cost per megalitre 
storage capacity ($/ML) the more suitable the site for a large offstream storage. Analysis does not take into account 
geological considerations, hydrology or proximity to water. Only sites with a minimum cost-to-storage-volume ratio of 
less than $5000/ML are shown. Costs are based on unit rates and quantity of material and site establishment for a 
roller compacted concrete dam. Inset displays height and width of dam wall at full supply level at the minimum cost 
per megalitre storage capacity. 

Potential storage sites cost, map
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For more information on this figure please contact CSIRO on enquiries@csiro.au

In Figure 5-15, only those locations with a ratio of cost to storage less than $5000/ML are shown. 
This is a simple way to display those locations in the Southern Gulf catchments with the most 
favourable topography for a large reservoir relative to the size (i.e. cost) of the dam wall necessary 
to construct the reservoir. This figure can be used to identify more promising sites for offstream 
storage (i.e. where some or all of the water is pumped into the reservoir from an adjacent 
drainage line). The threshold value of $5000/ML is nominal and was used to minimise the amount 
of data displayed. This analysis does not consider evaporation, hydrology or geological suitability 
for dam construction. 

Figure 5-15 shows that those parts of the Southern Gulf catchments with the most favourable 
topography for storing water are on the larger drainage lines on the uplands, in particular the 
Nicholson and Gregory rivers, Gunpowder Creek and the Leichhardt River. 

Major instream dams for water and irrigation supply 

In addition to suitable topography (and geology), instream dams require sufficient inflows to meet 
a potential demand. Potential dams that command smaller catchments with lower runoff have 
smaller yields. Results concerning this criterion are presented in terms of minimum cost per unit 
yield, where the smaller the cost per megalitre yield ($/ML) the more favourable the site for a 
large instream dam. The potential for major instream dams to cost-effectively supply water is 
presented in Figure 5-16. No values greater than $10,000/ML are shown. 

The DamSite modelling results shown in Figure 5-16 indicate that the most cost-effective potential 
dam sites are on the Nicholson and Gregory rivers and Gunpowder Creek. The streamflow inputs 
to the DamSite modelling undertaken for the Southern Gulf catchments did not consider existing 
storages on the Leichhardt River, and hence the suitability of those sites shown on the Leichhardt 
River would be further diminished with reduced inflows. Also shown on this figure is the versatile 
agricultural land for the Southern Gulf catchments, with the most versatile agricultural land 
occurring on the Carpentaria Plain (Thomas et al., 2024). 

Based on this analysis and a broad-scale desktop geological evaluation, seven of the more cost-
effective larger-yielding sites in distinct geographical areas that are proximal to soils suitable for 
irrigated agriculture were selected for pre-feasibility analysis (see companion technical report on 
surface water storage, Yang et al., 2024) to explore the potential opportunities and risks of water 
supply dams in the Southern Gulf catchments. The locations of these pre-feasibility potential dam 
sites are denoted in Figure 5-16 by black circles and the letters ‘A’ to ‘G’. No potential sites 
upstream of Julius Dam on the Leichhardt River (Figure 5-17) were examined as part of the pre-
feasibility analysis as a dam upstream of Julius Dam would reduce the inflows and yield of the 
latter. 

Key parameters and performance metrics are summarised in Table 5-5 and an overall summary 
comment is recorded in Table 5-6. More detailed analysis of the seven pre-feasibility sites is 
provided in the companion technical report on surface water storage (Yang et al., 2024). 


 

Figure 5-16 Potential storage sites in the Southern Gulf catchments based on minimum cost per megalitre yield at 
the dam wall 

This figure indicates those sites more suitable for major dams in terms of cost per megalitre yield at the dam wall in 
85% of years overlain on versatile land surface (see companion technical report on land suitability, Thomas et al., 
2024). At each location the minimum cost per ML storage capacity is displayed. Only sites with a minimum cost to 
yield ratio less than $10,000/ML are shown. Costs are based on unit rates and quantity of material required for a roller 
compacted concrete dam with a flood design of 1 in 10,000. Right inset displays height of full supply level (FSL) at the 
minimum cost per ML yield and left inset displays width of FSL at the minimum cost per ML yield. Letters indicate 
potential dams listed in Table 5-5 and Table 5-6. 

Potential storage sites yield cost, map
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For more information on this figure please contact CSIRO on enquiries@csiro.au



 

Figure 5-17 Julius Dam on the Leichhardt River 

Photo: CSIRO 

Hydro-electric power generation potential in the Southern Gulf catchments 

The potential for major instream dams to generate hydro-electric power is presented in 
Figure 5-18 following an assessment of more than 50 million potential dam sites in the Southern 
Gulf catchments (Yang et al., 2024). This figure provides indicative estimates of hydro-electric 
power generation potential but does not consider the existence of supporting infrastructure or 
geological suitability for dam construction. No values greater than $45,000/MWh are shown. 

Although the topography of the Southern Gulf catchments is moderately suitable for large water 
storage dams (i.e. narrow constrictions downstream of broad valleys), the topography appears to 
be less suitable for dams for hydro-electric power generation due to the lack of relief that is 
required to provide potential elevation head. Aside from a specific site on the Gregory River, 
Gunpowder Creek, a major tributary of the Leichhardt River, is the most favourable drainage line 
for dams for the purpose of hydro-electric power generation in the Southern Gulf catchments due 
to the more favourable topography and its proximity to Mount Isa, a major power demand centre. 
A companion technical report on hydro-electric power generation (Entura, 2024) undertakes a 
pre-feasibility analysis of a site on Gunpowder Creek to explore the potential for hydro-electric 
power in the Southern Gulf catchments. 

A dam with a body of water
Description automatically generated






 

Figure 5-18 Southern Gulf catchments hydro-electric power generation opportunity map 

Costs are based on unit rates and quantity of material required for a roller compacted concrete dam with a flood 
design of 1 in 10,000. Right inset displays height of full supply level (FSL) at the minimum cost per megalitre yield and 
left inset displays width of FSL at the minimum cost per megalitre yield. 

 

Hydro power opportunity, map
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For more information on this figure please contact CSIRO on enquiries@csiro.au

Pre-feasibility-level assessment of potential major dams in the Southern Gulf catchments 

Seven potential dam sites in the Southern Gulf catchments were examined as part of this pre-
feasibility assessment. They are summarised in Table 5-5 and Table 5-6. More detailed 
descriptions of these seven potential dam sites, including impacts to migratory species and 
ecological impacts of reservoir inundation, are provided in the companion technical report on 
surface water storage (Yang et al., 2024). 

Table 5-5 Potential dam sites in the Southern Gulf catchments examined as part of the Assessment 

All hypothetical dams are assumed to be roller compacted concrete. Locations of potential dams are shown in 
Figure 5-16. Geology grade is an ordinal scale between 1 and 5 where grade 1 is best, grade 5 is worst. It is based on a 
holistic assessment based on whether bedrock is exposed at site, likely depth of weathering/stripping on abutments, 
likely depth of cut-off and presence of deep alluvium, and overall height-to-width assessment. AMTD = adopted 
middle thread distance; FSL = full supply level; O&M = operation and maintenance. 

For more information on this table please contact CSIRO on enquiries@csiro.au
*The height of the dam abutments and saddle dams will be higher than the spillway height. 
**Water yield is based on 85% annual time-based reliability using a perennial demand pattern for the baseline river model under Scenario AE. This 
is yield at the dam wall (i.e. does not take into account distribution losses or downstream transmission losses). With the exception of the Gregory 
River AMTD 174 km site and the Gunpowder Creek AMTD 66 km site, the yield values do not take into account downstream existing entitlement 
holders. At none of the sites do the yield estimates take into account of environmental considerations. 
# Indicates manually derived preliminary cost estimate, which is likely to be –10% to +50% of ‘true cost’.  Indicates modelled preliminary cost 
estimate, which is likely to be –25% to +100% of ‘true’ cost. Should site geotechnical investigations reveal unknown unfavourable geological 
conditions, costs could be substantially higher. 
##The unit cost of annual water supply and is calculated as the capital cost of the dam divided by the water yield at 85% annual time reliability. 
###Assumes a 7% real discount rate and a dam service life of 100 years. Includes operation and maintenance (O&M) costs, assuming operation and 
maintenance (O&M) costs are 0.4% of the total capital cost. 



Table 5-6 Summary comments for potential dams in the Southern Gulf catchments 

Locations of potential dams are shown in Figure 5-16. AMTD = adopted middle thread distance. 

SITE NAME 

MAP ID 

SUMMARY COMMENT 

South Nicholson 
River 
AMTD 9 km 

A 

This potential dam site is the most expensive of those on the short-list and is a considerable distance 
upstream of the soil potentially suitable for irrigated agriculture. Furthermore, the site is very remote and 
access would require considerable additional infrastructure. At the adopted full supply level (FSL), the 
inundation extent of this potential dam site overlaps with parts of the Ganalanga–Mindibirrina Indigenous 
Protected Area (IPA). There is a high likelihood of unrecorded sites of cultural significance in the 
inundation area. Asset models predicted that 46% of the catchment has habitat suitable for at least one 
of the ten modelled migratory species, which constitutes zero % to 6.4% of the total habitat modelled as 
suitable in the Southern Gulf catchments. 

Gold Creek 
AMTD 58 km 

B 

This small potential instream dam site on a small catchment in the Settlement Creek Australian Water 
Resources Council river basin has a low yield and high cost per megalitre released from the dam wall. 
Downstream of the site, water could potentially be supplied to land with soils suitable for agriculture, 
with minor or moderate limitations, depending on the land use. Approximately 11% of the catchment was 
estimated as having habitat suitable for 40% or more of the (11) migratory species modelled. There is a 
high likelihood of unrecorded sites of cultural significance in the inundation area. 

Nicholson River 
AMTD 198 km 

C 

This potential instream development has the potential to release water for irrigation along the Nicholson 
River to the Doomadgee and Armraynald plains and Doomadgee. The foundations appear to be suitable 
for a roller compacted concrete (RCC) dam. Nonetheless, the site is very remote and is one of the more 
expensive potential dam sites examined in the Southern Gulf catchments. At the adopted FSL, the 
inundation extent of this potential dam site overlaps with parts of the Ganalanga–Mindibirrina IPA. There 
is a high likelihood of unrecorded sites of cultural significance in the inundation area. 

Gregory River 
AMTD 174 km 

D 

The potential Gregory River dam site is an instream development with potential to supply water to the 
large contiguous areas of black and grey cracking clay soils on the Armraynald Plain immediately 
downstream of the dam. Given the potential for significant flooding during construction and the spillway 
capacity required, an RCC gravity dam with a 400 m wide central uncontrolled spillway would be most 
suitable. The site is one of the largest-yielding and most cost-effective potential dam sites in the Southern 
Gulf catchments, and the foundations of this site appear to be suitable for an RCC dam. A major limitation 
of the site is its proximity to the Boodjamulla (Lawn Hill) National Park (upstream of the site), and the 
Thorntonia Aggregation wetland, which is up and downstream of the potential dam site. Despite being on 
a major river, the area of potentially suitable habitat for the four modelled migratory species was 
relatively small. There is a high likelihood of unrecorded sites of cultural significance in the inundation 
area. Limiting the FSL of the potential dam so that the area inundated would not extend into the 
Boodjamulla National Park resulted in a modelled yield of 180 GL in 85% of years at the dam wall. 
However, taking into consideration existing downstream users and assuming a dry-season crop resulted in 
a modelled yield of 133 GL in 85% of years. 

Gunpowder 
Creek AMTD 
66 km 

E 

This potential dam site is on Gunpowder Creek, a large tributary of the Leichhardt River, and it has the 
second-lowest cost per megalitre of the short-listed sites in the Southern Gulf catchments. The 
foundations appear to the suitable for an RCC dam. The site would nominally supply water to a large plain 
of recent alluvium at the junction of Gunpowder Creek and the Leichhardt River. There is a high likelihood 
of unrecorded sites of cultural significance in the inundation area. The area of potentially suitable habitat 
for modelled migratory species upstream of this dam site is relatively small. Previous studies of dams on 
Gunpowder Creek focused on areas further upstream, predominantly to supply water for mining. 

Mistake Creek 
AMTD 60 km 

F 

This potential dam site would supply water to large areas of contiguous soils suitable for irrigated 
agriculture on the Carpentaria Plains. Being a relatively small tributary of the Leichhardt River, the site has 
a low yield, and it has the highest cost per megalitre released from the dam wall of all the short-listed 
sites examined in the Southern Gulf catchments. There is a high likelihood of unrecorded sites of cultural 
significance in the inundation area. For the migratory species modelled as part of the Assessment, the 
catchment of a dam at this potential site would constitute less than 1% of the total potentially suitable 
habitat modelled in the Southern Gulf catchments. 

Ewen Creek 
AMTD 6 km 

G 

This low-yielding and relatively expensive potential dam site is located on the tributary that joins the 
Leichhardt River downstream of Lake Julius. The foundations appeared to be suitable for a RCC dam; 
however, the amount of dolomite rock in the foundation may represent a problem, due to cavities within 
dolomite strata. This would need to be investigated. Given the small catchment area and modest 
percentage of habitat suitable for migratory species upstream of the potential dam (22% for at least one 
species), a potential dam at this location would have an effect on zero % to 0.5% of the total potentially 
suitable habitat modelled in the Southern Gulf catchments. There is a high likelihood of unrecorded sites 
of cultural significance in the inundation area. 




The investigation of a potential large dam site generally involves an iterative process of 
increasingly detailed studies over a period of years, occasionally over as few as 2 or 3 years but 
often over 10 or more years. It is not unusual for the cost of the geotechnical investigations for a 
potential dam site alone to exceed several million dollars. For any of the options listed in this 
report to advance to construction, far more comprehensive studies would be needed, including 
geotechnical investigations, field measurements of sediment yield, archaeological surveys and 
ground-based vegetation and fauna surveys, as well as extensive consultations with Traditional 
Owners and other stakeholders. Studies at that detail are beyond the scope of this regional-scale 
resource assessment. The companion technical report on surface water storage (Yang et al., 2024) 
outlines the key stages in investigation of design, costing and construction of large dams. More 
comprehensive descriptions are provided by Fell et al. (2005), while Indigenous Peoples’ views on 
large-scale water development in north-eastern Queensland can be found in the companion 
technical report on Indigenous aspirations, interests and water values (Lyons et al., 2024). 

Other important considerations 

Cultural heritage considerations 

Indigenous Peoples traditionally situated their campsites, and hunting and foraging activities, 
along major watercourses and drainage lines. Consequently, dams are more likely to affect areas 
of high cultural significance than are most other infrastructure developments (e.g. irrigation 
schemes, roads). 

No field-based cultural heritage investigations of potential dam and reservoir locations were 
undertaken in the Southern Gulf catchments as part of the Assessment. However, based on 
existing records and statements from Indigenous participants in the Assessment, it is highly likely 
such locations will contain heritage sites of cultural, historical and wider scientific significance. 
Information relating to the cultural heritage values of the potential major dam sites is insufficient 
to allow full understanding or quantification of the likely impacts of water storages on Indigenous 
cultural heritage. 

The cost of cultural heritage investigations associated with large instream dams that could 
potentially impound large areas is high relative to other development activities. 

Ecological considerations of the dam wall and reservoir 

The water impounded by a major dam inundates an area of land, drowning not only instream 
habitat but surrounding flora and fauna communities. Complex changes in habitat resulting from 
inundation could create new habitat to benefit some of these species, while other species would 
be affected by loss of habitat. 

For instream ecology, the dam wall acts as a barrier to the movements of plants, animals and 
nutrients, potentially disrupting connectivity of populations and ecological processes. There are 
many studies linking water flow with nearly all the elements of instream ecology in freshwater 
systems (e.g. Robins et al., 2005). The impact of major dams on the movement and migration of 
aquatic species will depend upon the relative location of the dam walls in a catchment. For 
example, generally a dam wall in a small headwater catchment will have less of an impact on the 
movement and migration of species than a dam lower in the catchment. 


A dam also creates a large, deep lake, a habitat that is in stark contrast to the usually shallow and 
often flowing, or ephemeral, habitats it replaces. This lake-like environment favours some species 
over others and will function completely differently to natural rivers and streams. The lake-like 
environment of an impoundment is often used by sports anglers to augment natural fish 
populations by artificial stocking. Whether fish stocking is a benefit of dam construction is a 
matter of debate and point of view. Stocked fisheries provide a welcome source of recreation and 
food for fishers, and no doubt an economic benefit to local businesses, but they have also created 
a variety of ecological challenges. Numerous reports of disruption of river ecosystems (e.g. 
Drinkwater and Frank, 1994; Gillanders and Kingsford, 2002) highlight the need for careful study 
and regulatory management. Impounded waters may be subject to unauthorised stocking of 
native fish and releases of exotic flora and fauna. 

Further investigation of any of these potential dam sites would typically involve a thorough field 
investigation of vegetation and fauna communities. Ecological assets in the Victoria catchment are 
discussed in Section 3.2 and described in more detail in the companion technical reports on 
ecological assets (Merrin et al., 2024) and surface water storage (Yang et al., 2024). 

Potential changes to instream, riparian and near-shore marine species arising from changes in flow 
are discussed in Section 7.3 . 

Sedimentation 

Rivers carry fine and coarse sediment eroded from hill slopes, gullies and banks, and sediment 
stored within the channel. The delivery of this sediment into a reservoir can be a problem because 
it can progressively reduce the volume available for active water storage. The deposition of 
coarser-grained sediments in backwater (upstream) areas of reservoirs can also cause back-
flooding beyond the flood limit originally determined for the reservoir. 

Although infilling of the storage capacity of smaller dams has occurred in Australia (Chanson, 
1998), these dams had small storage capacities, and infilling of a reservoir is generally only a 
potential problem where the volume of the reservoir is small relative to the catchment area. 
Sediment yield is strongly correlated to catchment area (Tomkins, 2013; Wasson, 1994). Sediment 
yield to catchment area relationships developed for northern Australia (Tomkins, 2013) were 
found to predict lower sediment yield values than global relationships. This is not unexpected 
given the antiquity of the Australian landscape (i.e. it is flat and slowly eroding under ‘natural’ 
conditions). 

Using the relationships developed by Tomkins (2013), potential major dams in the Southern Gulf 
catchments were estimated to have about 2% or less sediment infilling after 30 years and less than 
5% sediment infilling after 100 years. The exception is the potential dam at Gregory River AMTD 
174 km with an FSL of 138 mEGM96 to avoid incursion of the reservoir into the Boodjamulla 
National Park upstream. At this FSL the reservoir capacity is small (118 GL) relative to the 
catchment area of the potential dam (11,381 km2), and consequently it was estimated sediment 
could potentially infill about 15% and 50% of the reservoir’s capacity after 30 years and 100 years, 
respectively. 


Cumulative yield of multiple hypothetical dams in the Southern Gulf catchments 

This analysis examined the combined or cumulative yield of multiple dams in the Southern Gulf 
catchments and the resulting impact to end-of-system (EOS) flows. To undertake this analysis, the 
most promising hypothetical dam sites (in terms of lowest cost per megalitre at the dam wall) 
were incrementally included in each river model simulation. Cumulative yields are reported at the 
dam wall and do not include transmission and conveyance losses. Figure 5-19 shows the 
cumulative yield (left y-axis) from sequential dams as triangles, and the percentage change in 
median annual EOS volume is represented as circles on the right y-axis. The total yield at the dam 
wall at an annual time reliability of 85% while also maintaining supply to existing entitlement 
holders downstream of six of the seven instream dams analysed is 733 GL, with the majority of 
this yield provided by the first three dams (641 GL). The seventh dam, South Nicholson River 
AMTD 9 km, is not included in this analysis as it is upstream of the Nicholson River AMTD 198 km 
dam, resulting in reduced cumulative yield. The results from this analysis were used to investigate 
the cumulative impacts of multiple dams in the Southern Gulf catchments (Section 7.3). 

 

Figure 5-19 Cumulative yield at 85% annual time reliability versus cumulative cost of water in $/ML and change in 
the end-of-system (EOS) volume in the Southern Gulf catchments 

Yield is reported at the dam wall under Scenario A. Triangles indicate combined water yield at 85% annual time 
reliability of one or more dams, and the colour of the dot indicates the most recently included dam in the cumulative 
yield calculation. Circles indicate change in median annual streamflow at the EOS for all mainland catchments 
compared to under Scenario A. 

 

For more information on this figure please contact CSIRO on enquiries@csiro.au

Exploration of two potential dam sites in the Southern Gulf catchments 

Two potential dam sites on different rivers are summarised here. These sites are described 
because they are among the more cost-effective sites near relatively large continuous areas of 
land suitable for irrigated agriculture in the Southern Gulf catchments, and not too remote relative 
to other potential dam sites in the study area. More detailed descriptions of the seven sites 
selected for pre-feasibility assessment are provided in the companion technical report on surface 
water storage (Yang et al., 2024). 

Potential dam on Gunpowder Creek AMTD 66 km and FSL 186 mEGM96 for water supply 

The potential Gunpowder Creek dam site is an instream development with the potential to 
provide irrigation supplies downstream near the junction of Gunpowder Creek and the Leichhardt 
River. Previous investigations commissioned by the then Queensland Irrigation and Water Supply 
Commission (QWIS, 1960, 1974) in the 1970s examined a number of potential dam sites along 
Gunpowder Creek for their potential to supply proposed mining developments. The potential sites 
investigated by the Queensland Irrigation and Water Supply Commission are upstream of the 
potential dam site examined in this section. There have been no recent publicly funded 
investigations. The foundations at the nominated site appear suitable for an RCC dam and it is 
estimated that both the depth of alluvium and stripping on the abutments would be about 3 to 
5 m. However, the extent of any dolomite in the sequence at the potential dam site should be 
checked in case there are strata with cavities, although the previous investigations at nearby sites 
did not note any problems. Given the potential for significant flooding during construction and the 
spillway capacity required, an RCC dam with a 140 m wide central uncontrolled spillway would be 
most suitable. Releases of water downstream of the dam could be made through two conduits 
installed in the right abutment of the dam, and would be regulated by two 900 mm diameter 
fixed-cone regulating valves. A fish-lift transfer facility would be installed in the right abutment of 
the potential dam. 

No site-specific evaluation of cultural heritage considerations was possible, as pre-existing 
Indigenous cultural heritage site records were not made available to the Assessment. Land tenure 
and native title information were derived from regional land councils and the National Native Title 
Tribunal. There is a high likelihood of unrecorded sites of cultural significance in the inundation 
area. Habitat species distribution models developed for the study area estimate that 
approximately 5% of the potential dam catchment (18,028 ha) has suitable habitat for at least 40% 
of the ten species modelled (Figure 5-20). The estimated area of suitable habitat for these water-
dependent species upstream of the potential dam site is small relative to the total estimated 
suitable habitat in the Southern Gulf catchments, ranging from zero% to 3% of the study area 
depending on the species. These species may have their habitat fragmented, and/or their 
movement may be impeded by a dam. 

A manual cost estimate undertaken as part of the Assessment for a hypothetical RCC dam on the 
Gunpowder Creek AMTD 66 km site at an FSL of 186 mEGM96 was approximately $773 million. 
Access to the site could be along a 75 km long extension of the existing Mount Isa to Gunpowder 
Road, although this extension would require further investigation should this proposal be 
considered further. The total distance from Mount Isa to the dam site would be 205 km. Assuming 


full use of existing licence entitlement holders in the Leichhardt catchment and a dry-season 
demand pattern, the yield at 85% annual time reliability and FSL of 186 mEGM96 was modelled to 
be 119 GL at the dam wall (Gibbs et al., 2024). Figure 5-21 shows the modelled dam cost and yield 
at the dam wall without consideration of existing entitlement holders. 

 

Figure 5-20 Location of listed species, water-dependent assets and aggregated modelled habitat in the vicinity of 
the potential dam site on Gunpowder Creek dam AMTD 66 km and reservoir extent 

Near the junction of Gunpowder Creek and the Leichhardt River, approximately 35 km 
downstream of the potential dam site, a large plain of recent alluvium has formed. The nearest 
location for a potential re-regulating structure appears to be about 5 km upstream of the 
hypothetical target area. Friable non-cracking clay or clay loam soils (soil generic group (SGG) 2) 
and sand to loam over relatively friable red clay subsoils (SGG 1.1) have formed on the recent 
alluvium of the floodplain. Brown cracking clay soils (SGG 9) occur on the older Cloncurry Plain. 

Gunpowder Ck dam water-dependent assets, map
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Figure 5-21 Potential dam site on Gunpowder Creek AMTD 66 km: cost and yield at the dam wall 

Dam length and dam cost versus full supply level (FSL), and (b) dam yield and yield/$ million at 75% and 85% annual 
time reliability. 

Due to the relatively steep slope of the land adjacent to the re-regulating weir and due to the 
texture of the soils, the likely irrigation application methods being spray or trickle, piped 
reticulation from the weir pump station would be likely. It is possible that this potential dam site 
could service about 11,000 ha, depending on crop type, irrigation method and reticulation 
arrangement (see companion technical report on irrigation systems in the Victoria and Southern 
Gulf catchments, Devlin, 2024). Based on a notional layout of pipeline infrastructure outlined by 
Devlin (2024), the cost of reticulation infrastructure to irrigate this area would be about 
$320 million or about $29,100 per irrigated hectare. 

Potential dam on Gregory River AMTD 174 km and FSL 138 mEGM96 for water supply 

The potential dam site on the Gregory River AMTD 174 km was first identified by the then 
Queensland Irrigation and Water Supply Commission in the late 1960s (QIWS, 1969) and 
subsequently identified by the Assessment as one of the largest-yielding and most cost-effective 
potential dam sites in the Southern Gulf catchments. There has been no recent consideration of 
this site for a potential water storage development. A major limitation of the site is its proximity to 
the Boodjamulla (Lawn Hill) National Park (upstream of the site), and parts of the Thorntonia 
Aggregation wetland, a Directory of Important Wetlands in Australia nationally important wetland, 
overlaps the potential reservoir and extends downstream from the potential dam wall. This 
hypothetical instream development has potential to supply water to the Armraynald Plain 
downstream of the dam. 

The hypothetical dam site is located on Proterozoic rocks of the Shady Bore Quartzite, which 
consists of white medium orthoquartzite, siltstone and dolomitic fine sandstone, which appear to 
be gently folded and dipping upstream. The foundations appear suitable for an RCC dam and the 
depth of alluvium is estimated to be 7 to 10 m; 5 to 7 m of stripping would be required on the 
potential dam abutments. 

Given the potential for significant flooding during construction, and the spillway capacity required, 
the RCC dam would have a 400 m wide central uncontrolled spillway. A hydraulic jump type 

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spillway basin would be provided to protect the river bed against erosion during spillway 
overflows. Releases downstream of the dam would be made through pipework installed in a 
diversion conduit located in the right abutment of the dam. A fish-lift transfer facility would also 
be installed in the right abutment. Access to the site would be along 27 km of new road built to 
serve the potential dam branching from the Camooweal–Gregory Road some 58 km south-west of 
Gregory. The total distance of the site from Mount Isa via Camooweal is 371 km. 

No site-specific evaluation of cultural heritage considerations was possible, as pre-existing 
Indigenous cultural heritage site records were not made available to the Assessment. Land tenure 
and native title information were derived from regional land councils and the National Native Title 
Tribunal. There is a high likelihood of unrecorded sites of cultural significance in the inundation 
area. 

Despite being on a major river, the potentially suitable habitat for the four modelled migratory 
species was relatively small. It was estimated that approximately 3% of the potential dam 
catchment (35,144 ha) has suitable habitat for at least 40% of the ten species modelled (Figure 
5-22). However, the estimated area of suitable habitat for these water-dependent species 
upstream of the potential dam site is small relative to the total estimated suitable habitat in the 
Southern Gulf catchments, ranging from 0.04% to 6.8% of the study area, depending on the 
species. These species may have fragmented habitat and/or their movement may be impeded by a 
dam. 


 

Figure 5-22 Location of listed species, water-dependent assets and aggregated modelled habitat in the vicinity of 
the potential dam site on the Gregory River AMTD 174 km 

The FSL 138 m EGM96 was selected such that the reservoir did not encroach into the Boodjamulla 
(Lawn Hill) National Park and Lawn Hill Resources Reserve, which are located about 9 km upstream 
of the potential dam wall. At this reduced FSL the yield is considerably reduced and the reservoir, 
which is small relative to its catchment area, has an elevated risk of having its capacity notably 
reduced by sediment infill (Yang et al., 2024). For example, taking into consideration existing 
licence entitlement holders and assuming a dry-season demand pattern, the yields at 85% annual 
time reliability at FSLs of 138 mEGM96 and 145 mEGM96 were modelled to be 133 GL and 233 GL 
at the dam wall, respectively (see companion technical report on river model simulation in the 
Southern Gulf catchments, Gibbs et al., 2024). Figure 5-23 shows the modelled dam cost and yield 
at the dam wall without consideration of existing entitlement holders. 

Gregory River dam water-dependent assets, map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\4_Water_storage\3_S_Gulf\1_GIS\1_Map_docs\WS532-S_Dam003_Ecology_v03_CR.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au

 

Figure 5-23 Potential dam site on Gregory River AMTD 174 km: cost and yield at the dam wall 

(a) Dam length and dam cost versus full supply level (FSL), and (b) dam yield and yield/$ million at 75% and 85% 
annual time reliability. 

A manual cost estimate undertaken as part of the Assessment for a hypothetical RCC dam on the 
Gregory River at AMTD 174 km at an FSL of 138 mEGM96 found the dam would cost 
approximately $683 million. 

Although the nearby Boodjamulla (Lawn Hill) National Park (upstream of the site) and Thorntonia 
Aggregation wetland are major limitations of this potential dam site, a major benefit is its 
proximity to the Armraynald Plain (approximately 35 km downstream of the potential dam site), 
which is a large contiguous area of Pleistocene sediments that formed black and grey cracking clay 
soils (SGG 9) suitable for a range of dry-season crops. Due to the slope of the Gregory River near 
the potential dam site, water would be released from the dam down the river to a potential re-
regulating weir on a natural bar with a 2.5 km long pool upstream. One of the favourable features 
of the site is that the river levees adjacent to the potential re-lift pump point mean the land 
naturally slopes away from the river at a gradient favourable for cost-effective open channels. 
Notionally the hypothetical scheme would be based around using two main channel alignments 
and constructed from the in-situ cracking clay soils. Under the nominal irrigation scheme outlined 
by Devlin (2024), a hypothetical dam on the Gregory River at AMTD 174 km and FSL 138 mEMG96 
could potentially supply sufficient water to irrigate approximately 10,000 ha at a reticulation 
scheme cost of $31.8 million or $3180/ha (excluding farm development and infrastructure; Devlin 
2024). 

5.4.3 Weirs and re-regulating structures 

Re-regulating structures, such as weirs, are typically located downstream of large dams. They 
allow for more efficient releases from the storages and for some additional yield from the weir 
storage itself, thereby reducing the transmission losses normally involved in supplemented river 
systems. 

As a rule of thumb, however, weirs are constructed to one-half to two-thirds of the river bank 
height. This height allows the weirs to achieve maximum capacity, while ensuring the change in 
downstream hydraulic conditions does not result in excessive erosion of the toe of the structure. It 

For more information on this figure please contact CSIRO on enquiries@csiro.au

also ensures that large flow events can still be passed without causing excessive flooding 
upstream. 

Two types of weir structures have been constructed in Queensland: concrete gravity weirs and 
sheet piling weirs. These are discussed below. For each type of weir, rock-filled mattresses are 
often used on the stream banks, extending downstream of the weir to protect erodible areas from 
flood erosion. A brief discussion on sand dams is also provided. 

Weirs, sand dams and diversion structures obstruct the movement of fish in a similar way to dams 
during the dry season. 

Concrete gravity type weirs 

Where rock bars are exposed at bed level across a stream, concrete gravity type weirs have been 
built on the rock at numerous locations across Queensland. This type of construction is less 
vulnerable to flood erosion damage, both during construction and in service. Indicative costs are 
provided for a small weir structure with only sufficient height (e.g. 0.75 m above river bed) to 
submerge pumping infrastructure. Assuming exposed bedrock across the river bed, and rock for 
aggregates and mattresses, are available locally, the cost of a low reinforced concrete slab with 
upstand (i.e. 0.75 m above river bed, nominally 150 m width along crest) for the purpose of 
providing pump station submergence is estimated to cost about $13 million. Nominal allowances 
were made for site access, services and construction camp costs on the basis that more substantial 
site establishment costs would be incurred by the nearby irrigation development (Yang et al., 
2024). 

Sheet piling weirs 

Where rock foundations are not available, stepped steel sheet piling weirs have been successfully 
used in many locations across Queensland. These weirs consist of parallel rows of steel sheet 
piling, generally about 6 m apart, with a step of about 1.5 to 1.8 m high between each row. 
Reinforced concrete slabs placed between each row of piling absorb much of the energy as flood 
flows cascade over each step. The upstream row of piling is the longest, driven to a sufficient 
depth to cut off the flow of water through the most permeable material (Figure 5-24). Indicative 
costs are provided in Table 5-7. 

In recent years the Queensland Department of Agriculture and Fisheries has not approved stepped 
weirs on the basis that the steps result in fish mortalities. Sheet piling weirs would therefore have 
to have a sloping face with a more extensive dissipator at bed level. 


 

Figure 5-24 Schematic cross-section of sheet piling weir 

Source: Petheram et al. (2013) 

Table 5-7 Estimated construction cost of 3 m high sheet piling weir 

Cost indexed to 2023. 

WEIR CREST LENGTH 
(m) 

ESTIMATED CAPITAL COST 
($ million) 

100 

32 

150 

42 

200 

50 



Sand dams 

As many of the large rivers in northern Australia are very wide (e.g. >300 m), weirs are likely to be 
impractical and expensive at many locations. An alternative structure is a sand dam, which 
consists of low embankments built of sand and constructed at the start of each dry season during 
periods of low or no flow, when heavy earth-moving machinery can access the bed of the river. A 
sand dam is constructed to form a pool of sufficient depth to enable pumping (i.e. typically greater 
than 4 m depth) and this type of dam is widely used in the Burdekin River near Ayr in Queensland, 
where the river is too wide to construct a weir. 

Typically, sand dams take three to four large excavators approximately 2 to 3 weeks to construct, 
and no further maintenance is required until they need to be reconstructed again after the wet 
season. Bulldozers can construct a sand dam more quickly than can a team of excavators, but they 
have greater access difficulties. Because a sand dam only needs to form a pool of sufficient size 
and depth from which to pump water, it usually only partially spans a river and is typically 
constructed immediately downstream of large, naturally formed waterholes. 

The cost of 12 weeks of hire for a 20 t excavator and float (i.e. for transportation) is approximately 
$100,000. Although sand dams are cheap to construct relative to a concrete or sheet piling weir, 
they require annual rebuilding and have much larger seepage losses beneath and through the dam 
wall. No studies are known to have quantified losses from sand dams. 

For more information on this figure please contact CSIRO on enquiries@csiro.au



5.4.4 Large farm-scale ringtanks 

Large farm-scale ringtanks are usually fully enclosed circular earthfill embankment structures 
constructed close to major watercourses/rivers to minimise the cost of pumping infrastructure by 
ensuring long ‘water harvesting’ windows. For this reason, they are often subject to reasonably 
frequent inundation, usually by slow-moving flood waters. In some exceptions embankments may 
not be circular; rather, they may be used to enhance the storage potential of natural features in 
the landscape such as horseshoe lagoons or cut-off meanders adjacent to a river (see Section 5.4.6 
for discussion on extracting water from persistent waterholes). 

An advantage of ringtanks over gully dams is that the catchment area of the former is usually 
limited to the land that it impounds, so costs associated with spillways, failure impact assessments 
and constructing embankments to withstand flood surges are considerably less than those for 
large farm-scale gully dams. Another advantage of ringtanks is that unless a diversion structure is 
utilised in a watercourse to help ‘harvest’ water from a river, a ringtank and its pumping station do 
not impede the movement of aquatic species or transport of sediment in the river. Ringtanks also 
have to be sited adjacent to major watercourses to ensure there are sufficient days available for 
pumping. While this limits where they can be sited, it means that because they can be sited 
adjacent to major watercourses (on which gully dams would be damaged during flooding – large 
farm-scale gully dams are typically sited in catchments of areas less than 40 km2), they often have 
a higher reliability of being filled each year than gully dams. However, operational costs of 
ringtanks are usually higher than those of gully dams because water must be pumped into the 
structure each year from an adjacent watercourse, typically using diesel-powered pumps (solar 
and wind energy do not generate sufficient power to operate high-volume axial flow or centrifugal 
flow pumps). Even where diversion structures are utilised to minimise pumping costs, the annual 
cost of excavating sediment and debris accumulated in the diversion channel can be in the order 
of tens of thousands of dollars. 

For more information on ringtanks in the Southern Gulf catchments, refer to the companion 
technical reports on surface water storage (Yang et al., 2024) and river model simulation (Gibbs et 
al., 2024). Also of relevance is the Northern Australia Water Resource Assessment technical report 
on large farm-scale dams (Benjamin, 2018) and companion technical report on pumping stations in 
northern Australia (Devlin, 2024). A rectangular ringtank in the catchment of the Flinders River 
(Queensland) is pictured in Figure 5-25. 

In this section, the following assessments of ringtanks in the Southern Gulf catchments are 
reported: 

• suitability of land for large farm-scale ringtanks 
• reliability with which water can be extracted from different reaches 
• indicative evaporative and seepage losses from large farm-scale ringtanks 
• indicative capital, operation and maintenance costs of large farm-scale ringtanks. 



 


Figure 5-25 Rectangular ringtank and 500 ha of cotton in the Flinders catchment (Queensland) 

The channel along which water is diverted from the Flinders River to the ringtank can be seen in the foreground. 

Photo: CSIRO 

Suitability of land for ringtanks in the Southern Gulf catchments 

Figure 5-26 displays the broad-scale suitability of land for large farm-scale ringtanks in the 
Southern Gulf catchments. Approximately 21% of the Southern Gulf catchments is classed as being 
likely suitable. Those areas of the Southern Gulf catchments with soil and topography suitable for 
ringtanks are mainly restricted to the level, slowly permeable, rock-free cracking clay soils (SGG 9) 
of the Armraynald Plain, Barkly Tableland and northern parts of Donors Plateau (Figure 5-26). The 
very poorly drained saline coastal marine plains (Karumba Plain), which are subject to tidal 
inundation and have very deep, strongly mottled, grey non-cracking and cracking clay soils with 
potential acid-sulfate deposits in the profile, are likely to be suitable for ringtanks but are subject 
to storm surge from cyclones. The soils of the Armraynald Plain are very deep (>1.5 m), 
imperfectly drained, slowly permeable, medium to heavy clays that crack when dry and swell 
when wet, reducing the rate of deep drainage. Soils have a self-mulching clay surface with gilgai 
common. On the Barkly Tableland, the cracking clays are deep (1.2 to 1.5 m) and underlain by 
limestone and dolomite karst, and hence are often moderately well drained and with gravel 
common. On Donors Plateau, the cracking clay soils are shallower (<0.5 m). 


 

Figure 5-26 Suitability of land for large farm-scale ringtanks in the Southern Gulf catchments 

Soil and subsurface data were only available to a depth of 1.5 m, hence the Assessment does not consider the 
suitability of subsurface material below this depth. This figure does not consider the availability of water. Data are 
overlaid on a shaded relief map. The results presented in this figure are only indicative of suitable locations for siting a 
ringtank; site-specific investigations by a suitably qualified professional should always be undertaken prior to ringtank 
construction. 

Ring tank suitability map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\4_Water_storage\3_S_Gulf\1_GIS\1_Map_docs\WS529-S-RingtankSuitability_v02_CR.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au

Reliability of water extraction 

The existence of a water entitlement does not mean the full volume will be available in all years. 
The reliability for extraction of an allocation or volume of water from a river depends upon a range 
of factors including the: 

•quantity of discharge and the natural inter- and intra-variability of a river system (Section 2.5.5)
•capacity of the pumps or diversion structure (expressed here as the number of days taken topump an allocation)
•quantity of water being extracted by other users, and their locations
•conditions associated with a licence to extract water, such as:
–a minimum threshold (i.e. water height level/discharge) at which pumping can commence(pump start threshold)
–an annual diversion commencement flow requirement (ADCFR), the volume that mustpass through the system before pumping can commence each water year (1 September to31 August). The ADCFR was assumed to be the combined outflow from rivers thatincluded hypothetical extractions, the Gregory–Nicholson and Leichhardt River basins.





Licence conditions can be imposed on a potential water user to ensure downstream entitlement 
holders are not affected by new water extractions and to minimise environmental change that 
may arise from changes to streamflow. In some cases a pump start threshold may be a physical 
threshold below which it is difficult to pump water from a natural pumping pool, but it can also be 
a regulatory requirement imposed to minimise impacts to existing downstream users and mitigate 
changes to existing water-dependent ecosystems. 

The impact of pump start thresholds and ADCFR flow requirements on extraction reliability are 
explored because they are the least complex environmental flow provision to regulate and ensure 
compliance in remote areas. Although more targeted environmental flow provisions may be 
possible, these are inevitably more complicated for irrigators to adhere to (usually requiring many 
dozens of pump operations during a season) and more difficult for regulators to enforce. Within 
each river reach, water could be harvested by one or more hypothetical water harvesters and the 
water nominally stored in ringtanks adjacent to the river reach. 

The reliability of water extraction under different conditions and at different locations in the 
Southern Gulf catchments is detailed in the companion technical report for river model simulation 
(Gibbs et al., 2024). A selection of plots from that report are provided in Figure 5-27 to Figure 5-31 
to illustrate key concepts. The locations of the hypothetical extractions are illustrated in the maps 
in the bottom right corners, and their relative proportions of the total system allocation (left 
vertical axis) were assigned based on joint consideration of crop versatility, broad-scale flooding, 
ringtank suitability and river discharge (see companion technical report on river modelling, Gibbs 
et al., 2024). 

Figure 5-27 can be used to explore the reliability of extracting (‘harvesting’) or diverting increasing 
volumes of water at five locations in the Southern Gulf catchments under varying pump start 
thresholds. The left vertical axis (y1-axis) indicates the system target volume, which is the 
maximum volume of water extracted across the Southern Gulf catchments each season (nominal 
catchment-wide entitlement volume). The right vertical axis (y2-axis) is the maximum volume of 
water extracted in that reach each season (nominal reach entitlement volume). 


 

Figure 5-27 Annual reliability of diverting annual system and reach target volumes for varying pump start thresholds 

The results assume no annual diversion commencement flow requirement before pumping can commence. Pump 
capacity is such that system and reach target volumes can be pumped in 20 days. Seven-digit numbers refer to model 
node locations. Black contour lines indicate conditions that meet a 75% annual reliability of supply, and grey contour 
lines on node 9139000 indicate proportion of years with a reduction in supply to existing users compared to Scenario 
A. For more detail see companion technical report on river modelling (Gibbs et al., 2024). 

"\\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\2_Hydrology\201_SG\6_River_model\SG_AWRAR\4_water_harvest\1_scripts\Catch_report_WH_plots.R"

This example assumes a 20-day pump capacity – that is, pump capacities are set to enable the 
system and reach target volumes to be pumped in 20 days (not necessarily consecutively). This 
means an irrigator with a 4 GL ringtank has a pump capacity of 200 ML/day to fill their ringtank in 
20 days. In this example there is no annual diversion commencement flow requirement based on 
the volume at the end of the system. 

At the smallest pump start threshold examined, 200 ML/day (nominally representative of a lower 
physical pumping limit), approximately 300 GL of water can be extracted in the Southern Gulf 
catchments in 75% of years; however, this relatively low pump start threshold results in some 
impacts on existing downstream licence holders along the Leichhardt River (grey contour lines on 
node 9139000 in Figure 5-27). This figure shows that as the total system and reach targets 
increase, the extraction reliability for that volume decreases. Similarly, as the pump start threshold 
increases, reducing the opportunities to extract water, the extraction reliability for the full system 
and reach targets decreases. At a pump start threshold of 600 ML/day, which does not affect 
existing users downstream, approximately 150 GL of water can be extracted in the Southern Gulf 
catchments in 75% of years. 

The data presented in Figure 5-28 are similar to that presented in Figure 5-27 except in Figure 5-28 
an additional extraction condition is imposed: a combined total of 150 GL has to flow past the 
outlets of the Gregory–Nicholson and Leichhardt rivers each wet season before any water can be 
extracted. Figure 5-28 shows that increasing the EOS flow requirement reduces the extraction 
reliability for the system and reach targets for different pump start thresholds. Figure 5-29 models 
increasing the pumping capacity by modifying the conditions such that the target volume can be 
extracted in 10 days instead of 20 days, with the result being that reliability of supply increases for 
a given target and pump start threshold. This relationship is shown in more detail in Figure 5-30, 
this time with pump rate in days on the x-axis instead of pump start threshold, which has been 
fixed to 600 ML/day. With a pump start threshold of 600 ML/day and an annual EOS flow 
requirement of 150 GL, large pump capacities (i.e. to enable pumping in 20 days or less) are 
required to extract the system and reach target volumes in 75% of years or greater. 

Figure 5-31 and Figure 5-32 indicate, respectively, the post-extraction 50% and 80% annual flow 
exceedance combined across the outlets with water harvest extractions upstream as a proportion 
of change relative to Scenario A. The median annual flow is relatively insensitive to the ADCFR flow 
requirement (Figure 5-31). However, in drier years (represented by the 80% annual flow 
exceedance data in Figure 5-32) the ADCFR flow requirement has the effect of ‘protecting’ 
streamflow, with a higher relative proportion of the Scenario A EOS flow maintained. 


 

Figure 5-28 Annual reliability of diverting annual system and reach target volumes for varying pump start thresholds 
with annual diversion commencement flow requirement of 150 GL 

Assumes pumping capacity of 20 days (i.e. system and reach target volumes can be pumped in 20 days). Seven-digit 
numbers refer to model node locations. Black contour lines indicate conditions that meet a 75% annual reliability of 
supply, and grey contour lines on node 9139000 indicate proportion of years with a reduction in supply to existing 
users compared to Scenario A. For more detail see companion technical report on river modelling (Gibbs et al., 2024). 

"\\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\2_Hydrology\201_SG\6_River_model\SG_AWRAR\4_water_harvest\1_scripts\Catch_report_WH_plots.R"



Figure 5-29 Annual reliability of diverting annual system and reach target volumes for varying pump start thresholds 
assuming pumping capacity of 10 days 

Annual diversion commencement flow requirement of 150 GL before pumping can commence and pumping capacity 
such that system and reach target volumes can be pumped in 10 days. Seven-digit numbers refer to model node 
locations. Black contour lines indicate conditions that meet a 75% annual reliability of supply, and grey contour lines 
on node 9139000 indicate proportion of years with a reduction in supply to existing users compared to Scenario A. For 
more detail see companion technical report on river modelling (Gibbs et al., 2024). 

"\\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\2_Hydrology\201_SG\6_River_model\SG_AWRAR\4_water_harvest\1_scripts\Catch_report_WH_plots.R"

 

Figure 5-30 Annual reliability of diverting annual system and reach target volumes for varying pump rates assuming 
a pump start threshold of 600 ML/day 

Annual diversion commencement flow requirement of 150 GL before pumping can commence. Seven-digit numbers 
refer to model node locations. Black contour lines indicate conditions that meet a 75% annual reliability of supply, and 
no grey contour lines on node 9139000 indicate no impact on reliability of supply to existing users (e.g. Figure 5-29) 
compared to Scenario A with a pump start threshold of 600 ML/day. For more detail see companion technical report 
on river modelling (Gibbs et al., 2024). 

"\\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\2_Hydrology\201_SG\6_River_model\SG_AWRAR\4_water_harvest\1_scripts\Catch_report_WH_plots.R"

 

Figure 5-31 50% annual exceedance (median) streamflow relative to Scenario A in the Southern Gulf catchments for 
a pump start threshold of 600 ML/day and a pump capacity of 20 days 

Seven-digit numbers refer to model node locations. For more detail see companion technical report on river modelling 
(Gibbs et al., 2024). ADCFR = Annual diversion commencement flow requirement, the volume flowing past the end of 
the system before pumping can commence. 

 

"\\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\2_Hydrology\201_SG\6_River_model\SG_AWRAR\4_water_harvest\1_scripts\Catch_report_WH_plots.R"



Figure 5-32 80% annual exceedance streamflow relative to Scenario A in the Southern Gulf catchments for a pump 
start threshold of 600 ML/day and a pump capacity of 20 days 

Seven-digit numbers refer to model node locations. For more detail see companion technical report on river modelling 
(Gibbs et al., 2024). ADCFR = Annual diversion commencement flow requirement, the volume flowing past the end of 
the system before pumping can commence. 



"\\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\2_Hydrology\201_SG\6_River_model\SG_AWRAR\4_water_harvest\1_scripts\Catch_report_WH_plots.R"

Evaporation and seepage losses 

Losses from a farm-scale dam occur through seepage and evaporation. 

A study of 138 farm dams ranging in capacity from 75 to 14,000 ML from southern NSW to central 
Queensland by the Cotton Catchment Communities CRC (2011) found mean seepage and 
evaporation rates of 2.3 and 4.2 mm/day, respectively. Of the 138 dams examined, 88% had 
seepage values of less than 4 mm/day and 64% had seepage values less than 2 mm/day. These 
results largely concur with those of the Irrigation Association of Australia (IAA, 2007), which states 
that reservoirs will have seepage losses equal to or less than 1 to 2 mm/day when constructed on 
suitable soils and greater than 5 mm/day if sited on less suitable (i.e. permeable) soils. 

When calculating evaporative losses from farm dams it is important to calculate net evaporation 
(i.e. evaporation minus rainfall) rather than just evaporation. Ringtanks with greater mean water 
depths lose a lower percentage of their total storage capacity to evaporation and seepage; 
however, they have a smaller ratio of storage capacity to excavation. In Table 5-8, effective 
volume refers to the actual volume of water that could be used for consumptive purposes after 
losses due to evaporation and seepage. For example, if water is stored in a ringtank with mean 
water depth of 3.5 m from April until January and the mean seepage loss is 2 mm/day, nearly 
three-quarters of the stored volume (i.e. 70%) would be lost to evaporation and seepage. The 
example provided in Table 5-8 is for a 4000 ML storage but the effective volume expressed as a 
percentage of the ringtank capacity is applicable to any storage (e.g. ringtanks or gully dams) of 
any capacity for mean water depths of 3.5, 6.0 and 8.5 m. 

Table 5-8 Effective volume after net evaporation and seepage for ringtanks of three mean water depths, under 
three seepage rates, near Century Mine in the Southern Gulf catchments 

Effective volume refers to the actual volume of water that could be used for consumptive purposes as a result of 
losses due to net evaporation and seepage, assuming the storage capacity is 4000 ML. For storages of 4000 ML 
capacity and mean water depths of 3.5, 6.0 and 8.5 m, reservoir surface areas are 110, 65 and 45 ha, respectively. 
Effective volumes are calculated based on the 20% exceedance net evaporation. For more detail see companion 
technical report on surface water storage (Yang et al., 2024). S:E ratio = storage capacity to excavation ratio. 

MEAN WATER 
DEPTH† 

(m) 

S:E 
RATIO 

SEEPAGE 
LOSS 

(mm/day) 

EFFECTIVE 
VOLUME 

(ML) 

EFFECTIVE 
VOLUME AS 
PERCENTAGE 
OF CAPACITY 

(%) 

EFFECTIVE 
VOLUME 

(ML) 

EFFECTIVE 
VOLUME AS 
PERCENTAGE 
OF CAPACITY 

(%) 

EFFECTIVE 
VOLUME 

(ML) 

EFFECTIVE 
VOLUME AS 
PERCENTAGE 
OF CAPACITY 

(%) 

























5 months 
(April to August) 

7 months 
(April to October) 

10 months 
(April to January) 

3.5 

14:1 

1 

2879 

72 

2327 

58 

1545 

39 



14:1 

2 

2711 

68 

2093 

52 

1210 

30 



14:1 

5 

2210 

55 

1390 

35 

203 

5 

6 

7.5:1 

1 

3332 

83 

3004 

75 

2537 

63 



7.5:1 

2 

3233 

81 

2865 

72 

2338 

58 



7.5:1 

5 

2937 

73 

2450 

61 

1744 

44 

8.5 

5:1 

1 

3535 

88 

3306 

83 

2981 

75 



5:1 

2 

3467 

87 

3210 

80 

2843 

71 



5:1 

5 

3262 

82 

2923 

73 

2432 

61 



†Mean water depth above ground surface. 












Strategies to minimise evaporation include liquid and solid barriers, but these are typically 
expensive per unit of inundated area (e.g. $12 to $40 per m2). In non-laboratory settings, liquid 
barriers such as oils are susceptible to being dispersed by wind and have not been shown to 
reduce evaporation from a water body (Barnes, 2008). Solid barriers can be effective in reducing 
evaporation but are expensive, at approximately two to four times the cost of constructing a 
ringtank. Evaporation losses from a ringtank can also be reduced slightly by subdividing the 
storage into multiple cells and extracting water from each cell in turn to minimise the total surface 
water area. However, constructing a ringtank with multiple cells requires more earthworks and 
incurs higher construction costs than outlined in this section. 
Capital, operation and maintenance costs of ringtanks 
Construction costs of a ringtank may vary considerably, depending on its size and the way the 
storage is built. For example, circular storages have a higher ratio of storage volume to excavation 
cost than rectangular or square storages. As discussed in the section on large farm-scale gully 
dams (Section 3.5.6), it is also considerably more expensive to double the height of an 
embankment wall than double its length due to the low angle of the walls of the embankment 
(often at a 3:1 ratio, horizontal to vertical). 
Table 5-9 provides a high-level breakdown of the capital and operation and maintenance (O&M) 
costs of a large farm-scale ringtank, including the cost of the water storage, pumping 
infrastructure, up to 100 m of pipes, and O&M costs of the scheme. In this example it is assumed 
that the ringtank is within 100 m of the river and pumping infrastructure. The cost of pumping 
infrastructure and conveying water from the river to the storage is particularly site specific. 
In flood-prone areas where flood waters move at moderate to high velocities, riprap (rocky 
material) protection may be required. The addition of riprap protection may increase the 
construction costs presented in Table 5-9 and Table 5-10 by 10% to 20% depending upon the 
volume of rock required and proximity to a quarry with suitable rock. 
For a more detailed breakdown of ringtank costs see the Northern Australia Water Resource 
Assessment technical report on large farm-scale dams (Benjamin, 2018), and for more information 
on pumping infrastructure see the companion technical report on pump stations for flood 
harvesting and irrigation downstream of storages (Devlin, 2024). 
356 | Water resource assessment for the Southern Gulf catchments 




Table 5-9 Indicative costs for a 4000 ML ringtank 

Assumes a 4.25 m wall height, 0.75 m freeboard, 3:1 ratio on upstream slope, 3:1 ratio on downstream slope and crest 
width of 3.1 m, approximately 60% of material can be excavated from within storage, and costs of earthfill and 
compacted clay are $5.40/m3 and $7/m3, respectively. Earthworks costs include vegetation clearing, 
mobilisation/demobilisation of machinery and contractor accommodation. For a more detailed costing, see the 
Northern Australia Water Resource Assessment technical report on large farm-scale dams (Benjamin, 2018). Pump 
station costs were derived from the companion technical report on pump stations in northern Australia (Devlin, 2023). 
Costs indexed to 2023. Pump station operation and maintenance (O&M) costs are based on a diesel cost of $1.49/L. 

SITE 
DESCRIPTION/ 
CONFIGURATION 

EARTHWORKS 
COSTS 
($) 

GOVERNMENT 
PERMITS AND 
FEES 
($) 

INVESTIGATION 
AND DESIGN 
FEES 
($) 

PUMP 
STATION 
COSTS 
($) 

TOTAL 
CAPITAL 
COST 
($) 

O&M 
COSTS OF 
RINGTANK 
($/y) 

O&M 
COSTS 
OF 
PUMP 
STATION 
($/y) 

TOTAL 
O&M 
COSTS 
($/y) 

4000 ML 
ringtank 

2,000,000 

43,000 

92,000 

380,000 

2,515,000 

21,000 

92,000 

113,000 



 
The capital costs can be expressed over the service life of the infrastructure (assuming a 7% 
discount rate) and combined with O&M costs to give an equivalent annual cost for construction 
and operation. This enables infrastructure with differing capital and O&M costs and service life to 
be compared. The total equivalent annual costs for the construction and operation of a 1000 ML 
ringtank with 4.25 m high embankments and 55 ML/day pumping infrastructure are approximately 
$143,600 (Table 5-10). For a 4000 ML ringtank with 4.25 m high embankments and 160 ML/day 
pumping infrastructure, the total equivalent annual cost is approximately $301,550. For a 4000 ML 
ringtank with 6.75 m high embankments and 160 ML/day pumping infrastructure, the total 
equivalent annual cost is approximately $457,600. 

Table 5-10 Annualised cost for the construction and operation of three ringtank configurations 

Assumes freeboard of 0.75 m, pumping infrastructure can fill ringtank in 25 days and assumes a 7% discount rate. 
Costs based on those provided for 4000 ML provided in Northern Australia Water Resource Assessment technical 
report on large farm-scale dams (Benjamin, 2018). Costs indexed to 2021. Pump station operation and maintenance 
(O&M) costs assume cost of diesel of $1.49/L. 

CAPACITY AND 
EMBANKMENT HEIGHT 

ITEM 

CAPITAL COST 

 
($) 

LIFE SPAN 


(y) 

ANNUALISED CAPITAL 
COST 

($) 

ANNUAL O&M 
COST 

($) 

1000 ML and 4.25 m 

Ringtank 

1,075,000 

40 

80,480 

10,700 

 

Pumping infrastructure† 

245,000 

15 

26,900 

4,500 

 

Pumping cost (diesel) 

NA 

NA 

NA 

21,000 

4000 ML and 4.25 m 

Ringtank 

2,000,000 

40 

150,000 

17,250 

 

Pumping infrastructure† 

380,000 

15 

41,700 

7,600 

 

Pumping cost (diesel) 

NA 

NA 

NA 

85,000 

4000 ML and 6.75 m 

Ringtank 

3,863,000 

40 

290,000 

33,300 

 

Pumping infrastructure† 

380,000 

15 

41,700 

7,600 

 

Pumping cost (diesel) 

NA 

NA 

NA 

85,000 



NA = data not available. 
†Costs include rising main, large-diameter concrete or multiple strings of high-density polypipe, control valves and fittings, concrete thrust blocks 
and headwalls, dissipator, civil works and installation. 


Although ringtanks with a mean water depth of 3.5 m (embankment height of 4.25 m) lose a 
higher percentage of their capacity to evaporative and seepage losses than ringtanks of equivalent 
capacity with mean water depth of 6 m (embankment height of 6.75 m) (Table 5-8), their 
annualised unit costs are lower (Table 5-11) due to the considerably lower cost of constructing 
embankments with lower walls (Table 5-10). 

In Table 5-11 the levelised cost, or the equivalent annual cost per unit of water supplied from the 
ringtank, takes into consideration net evaporation and seepage from the storage, which increase 
with the length of time water is stored (i.e. crops with longer growing seasons will require water 
to be stored longer). In this table, the results are presented for the equivalent annual cost of water 
yield from a ringtank of different seepage rates and lengths of time for storing water. 

Table 5-11 Equivalent annual cost per megalitre for two different capacity ringtanks under three seepage rates 
based on a climate station near the Century Zinc Mine in the Southern Gulf catchments 

Assumes a 0.75 m freeboard, 3:1 ratio on upstream slope, 3:1 ratio on downstream slope. Crest widths are 3.1 and 
3.6 m for embankments with heights of 4.25 and 6.75 m, respectively, and assumes earthfill and compacted clay costs 
of $5.40/m3 and $7/m3, respectively. Earthworks costs include vegetation clearing, mobilisation/demobilisation of 
machinery and contractor accommodation. 1000 ML ringtank reservoir has surface area of 27 ha and storage volume 
to excavation ratio of about 7:1. 4000 ML ringtank and 4.25 m embankment height reservoir has surface area of 
110 ha and storage volume to excavation ratio of about 14:1. 4000 ML ringtank with 6.75 m embankment height 
reservoir has surface area of 64 ha and storage volume to excavation ratio of about 7.5:1. Annualised cost indexed to 
2023 and assumes a 7% discount rate. 

For more information on this table please contact CSIRO on enquiries@csiro.au 



5.4.5 Large farm-scale gully dams 

Large farm-scale gully dams are generally constructed of earth, or earth and rockfill embankments 
with compacted clay cores, and usually to a maximum height of about 20 m, though most gully 
dams are homogenous fill embankments and their height is typically 8 m or less. Large farm-scale 
gully dams typically have a maximum catchment area of about 30 km2 due to the challenges in 
passing peak floods from large catchments (large farm-scale gully dams are generally designed to 
pass an event with an annual exceedance probability of 1%), unless a site has an exceptionally 
good spillway option. 

Like ringtanks, large farm-scale gully dams are a compromise between best-practice engineering 
and affordability. Designers need to follow accepted engineering principles relating to important 
aspects of materials classification, compaction of the clay core and selection of an appropriate 
embankment cross-section. However, costs are often minimised where possible; for example, by 
employing earth bywashes and grass protection for erosion control rather than more expensive 
concrete spillways and rock protection as found on major dams. This can compromise the integrity 
of the structure during extreme events, and the longevity of the structure, as well as increase the 
ongoing maintenance costs, but can considerably reduce the upfront capital costs. 

In this section the following assessments are reported: 

• suitability of the land for large farm-scale gully dams 
• indicative capital and O&M costs of large farm-scale gully dams. 


Net evaporation and seepage losses also occur from large farm-scale gully dams. The analysis 
presented in Section 5.4.4 is also applicable to gully dams. 

Suitability of land for large farm-scale gully dams 

Figure 5-33 indicates those locations where it is more topographically and hydrologically 
favourable to construct large farm-scale gully dams in the Southern Gulf catchments and the likely 
density of options. This analysis takes considers those sites likely to have more favourable 
topography. It does not explicitly consider those sites that are underlain by soil suitable for the 
construction of the embankment and to minimise seepage from the reservoir base. This is shown 
in Figure 5-34. In reality, dams can be constructed on eroded or skeletal soils provided there is 
access to a clay borrow pit nearby for the cut-off trench and core zone. However, these sites are 
likely to be less economically viable. 

These figures indicate that those parts of the Southern Gulf catchments that are more 
topographically suitable as large-scale gully dam sites generally do not coincide with areas with 
soils that are moderately suitable for irrigated agriculture. Furthermore, in many areas 
topographically suitable for gully dams, dam walls would need to be constructed from rockfill and 
imported clay soils, increasing the cost of their construction. There are, however, some locations 
in the north-west of Doomadgee in the Settlement Creek catchment and Mornington Island where 
there is some topography suitable for gully dams, soil suitable for their construction and versatile 
agricultural land nearby. 


 

Gully dam suitability and agricultural versatility, map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\4_Water_storage\3_S_Gulf\1_GIS\1_Map_docs\WS560-S_Gullydam_Damsite_Land_Versatile_v4_CR.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 5-33 Most economically suitable locations for large farm-scale gully dams in the Southern Gulf catchments 

Agricultural versatility data (see Section 4.3) indicate those parts of the catchment that are more or less versatile for 
irrigated agriculture. For the gully dam analysis, soil and subsurface data were only available to a depth of 1.5 m, 
hence this Assessment does not consider the suitability of subsurface material below this depth. Sites with catchment 
areas greater than 40 km2 or yield to excavation ratio less than 10 are not displayed. The results presented in this 
figure are modelled and consequently only indicative of the general locations where siting a gully dam may be most 
economically suitable. This analysis may be subject to errors in the underlying digital elevation model, such as effects 
due to the vegetation removal process. An important factor not considered in this analysis was the availability of a 
natural spillway. 


 

Gully dam suit and excavation yield ratio, map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\4_Water_storage\3_S_Gulf\1_GIS\1_Map_docs\WS561-S_Gullydam_Suitability_Damsite_v3_CR.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 5-34 Suitability of soils for construction of gully dams in the Southern Gulf catchments 

 


Capital, operation and maintenance costs of large farm-scale gully dams 

The cost of a large farm-scale gully dam will vary depending upon a range of factors, including the 
suitability of the topography of the site, the size of the catchment area, quantity of runoff, 
proximity of site to good-quality clay, availability of durable rock in the upper bank for a spillway 
and the size of the embankment. The height of the embankment, in particular, has a strong 
influence on cost. An earth dam to a height of 8 m is about 3.3 times more expensive to construct 
than a 4 m high dam, and a dam to a height of 16 m will require 3.6 times more material than the 
8 m high dam, but the cost may be more than five times greater, due to design and construction 
complexity. 

As an example of the variability in unit costs of gully dams, actual costs for four large farm-scale 
gully dams in northern Queensland are presented in Table 5-12. 

Table 5-12 Actual costs of four gully dams in northern Queensland 

Sourced from Northern Australia Water Resource Assessment technical report on farm-scale design and costs, 
(Benjamin, 2018). Costs indexed to 2023. 

Performance and cost of three hypothetical farm-scale gully dams in northern Australia 

A summary of the key parameters for three hypothetical 4 GL (i.e. 4000 ML) capacity farm-scale 
gully dam configurations is provided in Table 5-13 and a high-level breakdown of the major 
components of the capital costs for each of the three configurations is provided in Table 5-14. 
Detailed costs for the three hypothetical sites are provided in the Northern Australia Water 
Resource Assessment technical report on large farm-scale dams (Benjamin, 2018). 

Table 5-15 presents calculations of the effective volume for three configurations of 4 GL capacity 
gully dams (varying mean water depth/embankment height) for combinations of three seepage 
losses and water storage capacities over three time periods in the Southern Gulf catchments. 

Based on the information presented in Table 5-13, an equivalent annual unit cost including annual 
O&M cost for a 4 GL gully dam with a mean depth of about 6 m is about $220,000 (Table 5-16 and 
Table 5-17). 

Where the topography is suitable for large farm-scale gully dams and a natural spillway is present, 
large farm-scale gully dams are typically cheaper to construct than ringtanks. 


Table 5-13 Cost of three hypothetical large farm-scale gully dams of capacity 4 GL 

Costs include government permits and fees, investigation and design and fish passage. For a complete list of costs and 
assumptions see the Northern Australia Water Resource Assessment technical report on farm-scale dams (Benjamin, 
2018). Costs indexed to 2023. O&M = operation and maintenance; S:E ratio = storage capacity to excavation ratio. 

 

Table 5-14 High-level breakdown of capital costs for three hypothetical large farm-scale gully dams of capacity 4 GL 

Earthworks include vegetation clearing, mobilisation/demobilisation of equipment and contractor accommodation. 
Investigation and design fees include design and investigation of fish passage device and failure impact assessment 
(i.e. investigation of possible existence of population at risk downstream of site). Costs indexed to 2023. 

 


Table 5-15 Effective volumes and cost per megalitre for a 4 GL storage with different mean depths and seepage loss 
rates based on a climate station at the Century Zinc Mine in the Southern Gulf catchments 

Time periods of 4, 6 and 9 months refer to length of time water is stored or required for irrigation. 

 

Table 5-16 Cost of construction and operation of three hypothetical 4 GL gully dams 

Assumes operation and maintenance (O&M) cost of 3% of capital cost and a 7% discount rate. Figures have been 
rounded. 

 


Table 5-17 Equivalent annualised cost and effective volume for three hypothetical 4 GL gully dams with various 
mean depths and seepage loss rates based on climate data at Victoria River Downs Station in the Victoria 
catchment 

Dam details are in Table 5-16. Annual cost assumes a 7% discount rate. Time periods of 4, 6 and 9 months refer to 
length of time water is stored or required for irrigation. 

5.4.6 Natural water bodies 

Wetland systems and waterholes that persist throughout the dry season are natural water bodies 
characteristic of large parts of the northerly draining catchments of northern Australia. Many 
property homesteads in northern Australia use natural waterholes for stock and domestic 
purposes. However, the quantities of water required for stock and domestic supply are orders of 
magnitude less than those required for irrigated cropping, and it is partly for this reason that 
naturally occurring persistent water bodies in northern Australia are not used to source water for 
irrigation. 

For example, a moderately sized (5 ha) rectangular water body of mean depth 3.5 m may contain 
about 175 ML of water. Based on the data presented in Table 5-8 and assuming minimal leakage 
(i.e. 1 mm/day), approximately 72%, 58% and 39% of the volume would be available if a crop were 
to be irrigated until August, October and January, respectively. Assuming a crop or fodder with a 
6-month growing season requires 5 ML/ha of water before losses, and assuming an overall 
efficiency of 80% (i.e. the waterhole is adjacent to land suitable for irrigation, 95% conveyance 
efficiency and 85% field application efficiency), a 175 ML waterhole could potentially be used to 
irrigate about 20 ha of land for half a year if all the water was able to be used for this purpose. A 
large natural water body of 20 ha and mean depth of 3.5 m could potentially be used to irrigate 
about 80 ha of land if all the water was able to be used for this purpose. 

Although the areas of land that could be watered using natural water bodies are likely to be small, 
the costs associated with storing water are minimal. Consequently, where these waterholes occur 
at sufficient size and adjacent to land suitable for irrigated agriculture, they can be a very cost-
effective source of water. It would appear that where natural water bodies of sufficient size and 


suitable land for irrigation coincide, natural water bodies may be effective in staging a 
development (Section 6.3), where several hectares could potentially be developed, enabling 
lessons learned and mistakes made on a small-scale area before more significant capital 
investments are undertaken (noting that staging and learning are best to occur over multiple 
scales). 

In a few instances it may be possible to enhance the storage potential of natural features in the 
landscape such as horseshoe lagoons or cut-off meanders adjacent to a river. 

The main limitation to the use of wetlands and persistent waterholes for the consumptive use of 
water is that they have considerable ecological significance (e.g. Kingsford, 2000; Waltham et al., 
2013), and in many cases there is a limited quantity of water contained within the water bodies. In 
particular, water bodies that persist throughout the dry season are considered key ecological 
refugia (Waltham et al., 2013). 

For a water body situated in a sandy river, a waterhole is likely to be connected to water within 
the bedsands of the river. Hence, during and following pumping water within the bedsands of a 
river, the bedsands may in part replenish the waterhole and vice versa. While water within the 
bedsands of the river may in part replenish a depleted waterhole, in these circumstances it also 
means that pumping from a waterhole will have a wider environmental impact than just on the 
waterhole from which water is being pumped. 

5.5 Water distribution systems – conveyance of water from storage 
to crop 

5.5.1 Introduction 

In all irrigation systems, water needs to be conveyed from the water source through artificial 
and/or natural water distribution systems before ultimately being used on-field for irrigation. This 
section discusses water losses during conveyance and application of water to a crop, and the 
associated costs. 

5.5.2 Conveyance and application efficiencies 

Some water diverted for irrigation is lost during conveyance to the field before it can be used by a 
crop. These losses need to be taken into account when planning irrigation systems and developing 
likely irrigated areas. The amount of water lost during conveyance depends on the: 

•river conveyance efficiency, from the water storage to the re-regulating structure or point ofextraction
•channel distribution efficiency, from the river offtake to the farm gate
•on-farm distribution efficiency, in storing (using balancing storages) and conveying water fromthe farm gate to the field
•field application efficiency, in delivering water from the edge of the field and applying it to thecrop.


The overall or system efficiency is the product of these four components. 


Little research on irrigation systems has been undertaken in the Southern Gulf catchments. The 
time frame of the Assessment did not permit on-ground research into irrigation systems. 
Consequently, a brief discussion on the components listed above is provided based on relevant 
literature from elsewhere in Australia and overseas. Table 5-18 summarises the broad range of 
efficiencies associated with these components. 

The total conveyance and application efficiency of the delivery of water from the water storage to 
the crop (i.e. the overall or system efficiency) depends on the product of the four components in 
Table 5-18. For example, if an irrigation development has a river conveyance efficiency of 80%, a 
channel distribution efficiency of 90%, an on-farm distribution efficiency of 90% and a field 
application efficiency of 85%, the overall efficiency is 55% (80% × 90% × 90% × 85%). This means 
only 55% of all water released from the dam can be used by the crop. 

Table 5-18 Summary of conveyance and application efficiencies 

For more information on this table please contact CSIRO on enquiries@csiro.au
†River conveyance efficiency varies with a range of factors (including distance) and may be lower than the range quoted here. Under such 
circumstances, it is unlikely that irrigation would proceed. It is also possible for efficiency to be 100% in gaining rivers. Achieving higher efficiencies 
requires a re-regulating structure (Section 5.4.3). 

River conveyance efficiency 

The conveyance efficiency of rivers is difficult to measure and even more difficult to predict. 
Although there are many methods for estimating groundwater discharge to surface water, there 
are few suitable methods for estimating the loss of surface water to groundwater. In the absence 
of existing studies for northern Australia, conveyance efficiencies as nominated in water resource 
plans and resource operation plans for four irrigation water supply schemes in Queensland were 
examined collectively. The results are summarised in Table 5-19. 

The conveyance efficiencies in Table 5-19 are from the water storage to the farm gate and are 
nominated efficiencies based on experience delivering water in these supply schemes. These data 
can be used to estimate conveyance efficiency of similar rivers elsewhere. 


Table 5-19 Water distribution and operational efficiency as nominated in water resource plans for four irrigation 
water supply schemes in Queensland 

For more information on this table please contact CSIRO on enquiries@csiro.au
†Ignores differences in efficiency between high- and medium-priority users and variations across the scheme zone areas. 
‡Channel conveyance efficiency only. 

Channel distribution efficiency 

Across Australia, the mean water conveyance efficiency from the river to the farm gate has been 
estimated to be 71% (Marsden Jacob Associates, 2003). For heavier-textured soils and well-
designed irrigation distribution systems, conveyance efficiencies are likely to be higher. 

In the absence of larger scheme-scale irrigation systems in the Southern Gulf catchments, it is 
useful to look at the conveyance efficiency of existing irrigation developments to estimate the 
conveyance efficiency of irrigation developments in the study area. Australian conveyance 
efficiencies are generally higher than those found in similarly sized overseas irrigation schemes 
(Bos and Nugteren, 1990; Cotton Catchment Communities CRC, 2011). 

The most extensive review of conveyance efficiency in Australia was undertaken by the Australian 
National Commission on Irrigation and Drainage, which tabulated system efficiencies across 
irrigation developments in Australia (ANCID, 2001). Conveyance losses were reported as the 
difference between the volume of water supplied to irrigation customers and the water delivered 
to the irrigation system. For example, if 10,000 ML of water was diverted to an irrigation district 
and 8,000 ML was delivered to irrigators, then the conveyance efficiency was 80% and the 
conveyance losses were 20%. 

Figure 5-35 shows reported conveyance losses across irrigation areas of Australia between 1999 
and 2000, along with the supply method used for conveying irrigation water and associated 
irrigation deliveries. There is a wide spread of conveyance losses both between years and across 
the various irrigation schemes. Factors identified by Marsden Jacob Associates (2003) that affect 
the variation include delivery infrastructure, soil types, distance that water is conveyed, type of 
agriculture, operating practices, infrastructure age, maintenance standards, operating systems, in-


line storage, type of metering used, and third-party impacts such as recreational, amenity and 
environmental demands. Differences across irrigation seasons are due to variations in water 
availability, operational methods, climate and customer demands. 

 

For more information on this figure please contact CSIRO on enquiries@csiro.au
0%
15%
30%
45%
60%
0100,000200,000300,000400,000500,000600,000700,000800,000Losses 1999 to 2000 (percent)
Irrigation deliveries 1999 to 2000 (ML) 
NSWQldSATasVicWA
Figure 5-35 Reported conveyance losses from irrigation systems across Australia 

The shape of the marker indicates the supply method for the irrigation scheme: square (▪) indicates natural carrier, 
circle (•) indicates pipe and diamond (♦) indicates channel. The colour of the marker indicates the location of the 
irrigation system (by state), as shown in the legend. 

Source: ANCID (2001) 

Based on these industry data, Marsden Jacob Associates (2003) concluded that, on average, 29% 
of water diverted into irrigation schemes is lost in conveyance to the farm gate. However, some of 
this ‘perceived’ conveyance loss may be due to meter underestimation (about 5% of water 
delivered to provider (Marsden Jacob Associates, 2003)). Other losses were from leakage, 
seepage, evaporation, outfalls, unrecorded usage and system filling. 

On-farm distribution efficiency 

On-farm losses are losses that occur between the farm gate and delivery to the field. These losses 
usually take the form of evaporation and seepage from on-farm storages and delivery systems. 
Even in irrigation developments where water is delivered to the farm gate via a channel, many 
farms have small on-farm storages (i.e. less than 250 ML for a 500 ha farm). These on-farm 
storages enable the farmer to have a reliable supply of irrigation water with a higher flow rate, 
and also enable recycling of tailwater. Several studies have been undertaken in Australia for on-
farm distribution losses. Meyer (2005) estimated an on-farm distribution efficiency of 78% in the 
Murray and Murrumbidgee regions, while Pratt Water (2004) estimated on-farm efficiencies to be 
94% and 88% in the Coleambally Irrigation and Murrumbidgee Irrigation areas, respectively. For 
nine farms in these two irrigation areas, however, Akbar et al. (2000) measured channel seepage 
to be less than 5%. 


Field application efficiency 

After water is delivered to a field, it needs to be applied to the crop using an irrigation system. The 
application efficiency of irrigation systems typically varies between 60% and 90%, with more 
expensive systems usually resulting in higher efficiency. 

Three types of irrigation system can potentially be applied in the Southern Gulf catchments: 
surface irrigation, spray irrigation and micro irrigation (Figure 5-36). Irrigation systems applied in 
the Southern Gulf catchments need to be tailored to the soil, climate and crops that may be grown 
in the catchments and matched to the availability of water for irrigation. This is considered in the 
land suitability assessment figures presented in Section 4.2. System design will also need to 
consider investment risk in irrigation systems as well as likely returns, degree of automation, 
labour availability and O&M costs (e.g. the cost of energy). 

Irrigation systems have a trade-off between efficiency and cost. Table 5-20 summarises the 
different types of irrigation system, including their application efficiency, indicative cost and 
limitations. Across Australia the ratio of areas irrigated using surface, spray and micro irrigation is 
83:10:7, respectively. Irrigation systems that allow water to be applied with greater control, such 
as micro irrigation, cost more (Table 5-20) and as a result are typically used for irrigating higher-
value crops such as perennial horticulture and vegetables. For example, although only 7% of 
Australia’s irrigated area uses micro irrigation, it generates about 40% of the total value of 
produce grown using irrigation (Meyer, 2005). Further details on the three types of irrigation 
system follow Table 5-20. 

(a) 

(b) 

(c) 

 

 

 




Figure 5-36 Efficiency of different types of irrigation system 

(a) For bankless channel surface irrigation systems, application efficiencies range from 60% to 85%. (b) For spray 
irrigation systems, application efficiencies range from 75% to 90%. (c) For pressurised micro irrigation systems on 
polymer-covered beds, application efficiencies range from 80% to 90%. 

Photo: CSIRO 


Table 5-20 Application efficiencies for surface, spray and micro irrigation systems 

Application efficiency is the efficiency with which water can be delivered from the edge of the field to the crop. Costs 
indexed to 2023. 

For more information on this table please contact CSIRO on enquiries@csiro.au
Adapted from Hoffman et al. (2007), Raine and Bakker (1996) and Wood et al. (2007). 
†Sources: DEEDI (2011a, 2011b, 2011c). 

Surface irrigation systems 

Surface irrigation encompasses basin, border strip and furrow irrigation, as well as variations such 
as bankless channel systems. In surface irrigation, water is applied directly to the soil surface, with 
check structures (banks or furrows) used to direct water across a field. Control of applied water is 
dictated by the soil properties, soil uniformity and the design characteristics of the surface system. 
Generally, fields are prepared by laser levelling to increase the uniformity of applied water and 
allow ease of management of water and adequate surface drainage from the field. The uniformity 
and efficiency of surface systems are highly dependent on the system design and soil properties, 
timing of the irrigation water and the skill of the individual irrigator in operating the system. 
Mismanagement can severely degrade system performance and lead to systems that operate at 
poor efficiencies. 

Surface irrigation has the benefit that it can generally be adapted to almost any crop and usually 
has a lower capital cost compared with alternative systems. Surface irrigation systems perform 
better when soils are of uniform texture as infiltration characteristics of the soil play an important 
part in the efficiency of these systems. Therefore, surface irrigation systems should be designed 
into homogenous soil management units and layouts (run lengths, basin sizes) tailored to match 
soil characteristics and water supply volumes. 

High application efficiencies are possible with surface irrigation systems, provided soil 
characteristic limitations, system layout, water flow volumes and high levels of management are 
applied. On ideal soil types and with systems capable of high flow rates, efficiencies can be greater 
than 85%. On poorly designed and managed systems on soil types with high variability, efficiencies 
can be less than 60%. 

Generally, the major cost in setting up a surface irrigation system is land grading and levelling, 
with costs directly associated with the volume of soil that must be moved. Typical earth-moving 


volumes are in the order of 800 m3/ha but can exceed 2500 m3/ha. Volumes greater than 
1500 m3/ha are generally considered excessive due to costs (Hoffman et al., 2007). 

Surface irrigation systems are the dominant form of irrigation type used throughout the world. 
Their potential suitability in the Southern Gulf catchments would be due to their generally lower 
set-up costs and adaptability to a wide range of irrigated cropping activities. They are particularly 
suited to the heavier-textured soils on the alluvial plains adjacent to the Gregory and Leichhardt 
rivers and major tributaries, which reduce set-up or establishment costs of these systems. With 
surface irrigation, little or no energy is required to distribute water throughout the field, and this 
‘gravity-fed’ approach reduces energy requirements of these systems. 

Surface irrigation systems generally have lower applied irrigation water efficiency than spray or 
micro systems when compared across an industry and offer less control of applied water; 
however, well-designed and well-managed systems can approach efficiencies of alternative 
irrigation systems in ideal conditions. 

Spray irrigation systems 

In the context of the Southern Gulf catchments, spray irrigation refers specifically to lateral move 
and centre pivot irrigation systems. Centre pivot systems consist of a single sprinkler, laterally 
supported by a series of towers. The towers are self-propelled and rotate around a central pivot 
point, forming an irrigation circle. Time taken for the pivot to complete a full circle can range from 
as little as half a day to several days depending on crop water demands and application rate of the 
system. 

Lateral or linear move systems are similar to centre pivot systems in construction, but rather than 
move around a pivot point the entire line moves down a field perpendicular to the lateral 
direction. Water is supplied by a lateral channel running the length of the field. Lateral lengths are 
generally in the range of 800 to 1000 m. Their advantage over surface irrigation systems is they 
can be utilised on rolling topography and generally require less land forming. 

Both centre pivot and lateral move irrigation systems have been extensively used for irrigating a 
range of annual broadacre crops and are capable of irrigating most field crops. They are generally 
not suitable for tree crops or vine crops, or for saline irrigation water applications in arid 
environments, which can cause foliage damage. Centre pivot and lateral move systems usually 
have higher capital costs but are capable of very high efficiencies of water application. Generally, 
application efficiencies for these systems range from 75% to 90% (Table 5-20). They are used 
extensively for broadacre irrigated cropping situations in high evaporative environments in 
northern NSW and South West Queensland. These irrigation developments have high irrigation 
crop water demand requirements, which are similar to those found in the Southern Gulf 
catchments. A key factor in the suitable use of spray systems is sourcing the energy needed to 
operate these systems, which are usually powered by electricity or diesel depending on available 
costs and infrastructure. Where available, electricity is considerably cheaper than diesel for 
powering spray systems. 

For pressurised systems such as spray or micro irrigation systems, water can be more easily 
controlled, and potential benefits of the system through fertigation (application of crop nutrients 
through the irrigation system (i.e. liquid fertiliser)) are also available to the irrigator. 


Micro irrigation systems 

For high-value crops, such as horticultural crops where yield and quality parameters dictate 
profitability, micro irrigation systems should be considered suitable across the range of soil types 
and climate conditions in the Southern Gulf catchments. 

Micro irrigation systems use thin-walled polyethylene pipe to apply water to the root zone of 
plants through small emitters spaced along the drip tube. These systems are capable of precisely 
applying water to the plant root zone, thereby maintaining a high level of irrigation control and 
applied irrigation water efficiency. Historically, micro irrigation systems have been extensively 
used in tree, vine and row crops, with limited applications in complete-cover crops such as grains 
and pastures due to the expense of these systems. Micro irrigation is suitable for most soil types 
and can be practised on steep slopes. Micro irrigation systems are generally of two varieties: 
above-ground and below-ground (where the drip tape is buried beneath the soil surface). Below-
ground micro irrigation systems offer advantages in reducing evaporative losses and improving 
trafficability. However, below-ground systems are more expensive and require higher levels of 
expertise to manage. 

Properly designed and operated micro irrigation systems are capable of very high application 
efficiencies, with field efficiencies of 80% to 90% (Table 5-20). In some situations, micro irrigation 
systems offer water and labour savings and improved crop quality (i.e. more marketable fruit 
through better water control). Management of micro irrigation systems, however, is critical. To 
achieve these benefits requires a much greater level of expertise than for other traditional 
systems such as surface irrigation systems, which generally have higher margins of error 
associated with irrigation decisions. Micro irrigation systems also have high energy requirements, 
with most systems operating at pressure ranges from 135 to 400 kPa, with diesel or electric pumps 
most often used. 

5.6 References 

Akbar S, Beecher HG, Cullis B and Dunn B (2000) Using of EM surveys to identify seepage sites in 
on-farm channel and drains. Proceedings of the Irrigation Australia 2000 Conference, 
Australia. 

ANCID (2001) Australian irrigation water provider benchmarking report for 1999/2000. An ANCID 
initiative funded by Land and Water Australia and Department of Agriculture, Fisheries and 
Forestry−Australia, Australia. 

AWA (2018) Desalinisation factsheet. Australia Water Association. Viewed 10 April 2018, 
http://www.awa.asn.au/AWA_MBRR/Publications/Fact_Sheets/Desalination_Fact_Sheet.aspx. 

Barnes GT (2008) The potential for monolayers to reduce the evaporation of water from large 
water storages. Agricultural Water Management 95, 339–353. 

Benjamin J (2018) Farm-scale dam design and costs. A technical report to the Australian 
Government from the CSIRO Northern Australia Water Resource Assessment, part of the 
National Water Infrastructure Development Fund: Water Resource Assessments. CSIRO, 
Australia. 


Bos MG and Nugteren J (1990) On irrigation efficiencies, ILRI publication 19. International Institute 
for Land Reclamation and Improvement, Netherlands. 

Chanson H (1998) Extreme reservoir sedimentation in Australia: a review. International Journal of 
Sediment Research 13(3), 55–63. 

Cotton Catchment Communities CRC (2011) Storage seepage and evaporation. Final summary of 
results. Cotton storages project 2011. Cotton Catchment Communities CRC. 

DEEDI (2011a) More profit per drop – irrigated farming systems. Bankless channels – Bullamon 
Plains. Queensland Department of Employment, Economic Development and Innovation. 
Viewed 1 September 2013, Hyperlink to: More profit per drop – irrigated farming systems
. 

DEEDI (2011b) More profit per drop – irrigated farming systems. Centre pivot/lateral move 
irrigation. Queensland Department of Employment, Economic Development and Innovation. 
Viewed 1 September 2013, More Profit Per Drop website
. 

DEEDI (2011c) More profit per drop – irrigated farming systems. Drip irrigation. Queensland 
Department of Employment, Economic Development and Innovation. Viewed 12 November 
2013, More Profit Per Drop website
. 

Dillon P, Pavelic P, Page D, Beringen H and Ward J (2009) Managed aquifer recharge: an 
introduction. Waterlines Report Series no. 13. National Water Commission, Canberra. 

Doherty J (1999) Gravity dams. In: Cole B (ed) A history of dam technology in Australia 1850 – 
1999. Institution of Engineers, Australia and Australian National Committee on Large Dams. 

Drinkwater KF and Frank KT (1994) Effects of river regulation and diversion on marine fish and 
invertebrates. Aquatic Conservation Freshwater and Marine Ecosystems 4, 135–151. 

Evans WR, Evans RS and Holland GF (2013) Groundwater governance: a global framework for 
country action. Thematic paper 2: conjunctive use and management of groundwater and 
surface water within existing irrigation commands: the need for a new focus on an old 
paradigm. GEF ID 3726. 

Fell R, MacGregor P, Stapledon D and Bell G (2005) Geotechnical engineering of dams. Balkema 
Publishers. 

Gallant JC, Dowling TI, Read AM, Wilson N, Tickle P and Inskeep C (2011) 1 second SRTM derived 
digital elevation models user guide. Geoscience Australia. Viewed 19 March 2018, Geoscience Australia website
. 

Gibbs M, Hughes J, Yang A, Wang B, Marvanek S and Petheram C (2024) River model scenario 
analysis for the Southern Gulf catchments. A technical report from the CSIRO Southern Gulf 
Water Resource Assessment for the National Water Grid. CSIRO, Australia. 

Gillanders BM and Kingsford MJ (2002) Impact of changes in flow of freshwater on estuarine and 
open coastal habitats and the associated organisms. Oceanography and Marine Biology: an 
annual review 40, 233–309. 


Hoffman GJ, Evans RG, Jensen ME, Martin DL and Elliott RL (2007) Design and operation of farm 
irrigation systems. 2nd edition. American Society of Agricultural and Biological Engineers, St. 
Joseph, Michigan. 

IAA (2007) Guidelines for ring tank storages. In: Barrett H (ed) Irrigation Association of Australia 
Ltd. 

Jackson S, Stoeckl N and Straton A (2008) The changing value of Australian tropical rivers. 
Geographical Research 46, 275-290 

Kingsford RT (2000) Ecological impacts of dams, water diversions and river management on 
floodplain wetlands in Australia. Austral Ecology 25, 109–127. 

Knapton A, Taylor AR and Crosbie RS (2024) Groundwater flow modelling of the Cambrian 
Limestone Aquifer in the Undilla Sub-basin, Georgina Basin using a finite element 
groundwater flow model. A technical report from the CSIRO Southern Gulf Water Resource 
Assessment for the National Water Grid. CSIRO, Australia. 

Knapton A, Taylor AR, Petheram C and Crosbie RS (2023) An investigation into the effects of 
climate change and groundwater development scenarios on the water resources of the 
Roper catchment using two finite element groundwater flow models. A technical report 
from the CSIRO Roper River Water Resource Assessment for the National Water Grid. CSIRO, 
Australia., https://publications.csiro.au/publications/publication/PIcsiro:EP2023-5642. 

Lennon L, Evans R, George R, Dean F and Parsons S (2014) The role of managed aquifer recharge in 
developing northern Australia. Ozwater’14, Proceedings of Australia’s International Water 
Conference and Exhibition, Australian Water Association, Australia. 

Lewis B (2002) Farm dams: planning, construction and maintenance. Landlinks Press, Collingwood, 
Victoria. 

Lyons P, Barber M, Braedon P and Pert P (2024) Indigenous water values, rights, interests and 
development goals in the Southern Gulf Catchments: A literature review and implications for 
future research. A technical report from the CSIRO Southern Gulf Water Resource 
Assessment for the National Water Grid. CSIRO, Australia 

Marsden Jacob Associates (2003) Improving water-use efficiency in irrigation conveyance systems: 
a study of investment strategies. Marsden Jacob Associates, Land and Water Australia, 
Australia. 

Meyer WS (2005) The irrigation industry in the Murray and Murrumbidgee basins. Technical report 
no. 03/05. CSIRO Cooperative Research Centre for Irrigation Futures, Australia. 

Nace RL (1972) Water problems and developments of the past. Journal of the American Water 
Resources Association 8(1), 101–109. 

NRMMC-EPHC-NHMRC (2009) Australian guidelines for water recycling: managed aquifer 
recharge. National water quality management strategy document No. 24. Natural Resource 
Management Ministerial Council, Environmental Protection and Heritage Council, National 
Health and Medical Research Council. 

Petheram C, Rogers L, Eades G, Marvanek S, Gallant J, Read A, Sherman B, Yang A, Waltham N, 
McIntyre-Tamwoy S, Burrows D, Kim S, Podger S, Tomkins K, Poulton P, Holz L, Bird M, 


Atkinson F, Gallant S and Kehoe M (2013) Assessment of surface water storage options in 
the Flinders and Gilbert catchments. A technical report to the Australian Government from 
the CSIRO Flinders and Gilbert Agricultural Resource Assessment, part of the North 
Queensland Irrigated Agriculture Strategy. CSIRO Water for a Healthy Country and 
Sustainable Agriculture flagships, Australia. 

Petheram C, Rogers L, Read A, Gallant J, Moon A, Yang A, Gonzalez D, Seo L, Marvanek S, Hughes J, 
Ponce Reyes R, Wilson P, Wang B, Ticehurst C and Barber M (2017) Assessment of surface 
water storage options in the Fitzroy, Darwin and Mitchell catchments. A technical report to 
the Australian Government from the CSIRO Northern Australia Water Resource Assessment, 
part of the National Water Infrastructure Development Fund: Water Resource Assessments. 
CSIRO, Australia. 

Pratt Water (2004) The business of saving water: report of the Murrumbidgee Valley Water 
Efficiency Feasibility Project. Pratt Water, Campbellfield, Victoria. 

QWIS (1969) Progress report on preliminary investigations of dam sites. Gunpowder Creek and 
Gregory River. Queensland Irrigation and Water Supply Commission. November 1969. 

QWIS (1974) Gunpowder Creek 108.7 km Dam Project. Report on site access. Queensland 
Irrigation and Water Supply Commission. Job No. R1778. November, 1974. 

QWRC (1984) Farm water supplies design manual. Volume I farm storages. 2nd edition. In: 
Horton AJ and Jobling GA (eds) Farm Water Supplies Section, Irrigation Branch, Queensland 
Water Resources Commission. 

Raiber M, Taylor AR, Dupuy M, Priestley S, Crosbie RS, Knapton A, Hodgson G and Barry K (2024) 
Characterising groundwater resources of the Gilbert River Formation, Camooweal Dolostone 
and Thorntonia Limestone in the Southern Gulf catchments, Queensland and Northern 
Territory. A technical report from the CSIRO Southern Gulf Water Resource Assessment for 
the National Water Grid. CSIRO, Australia. 

Raine SR and Bakker DM (1996) Increased furrow irrigation efficiency through better design and 
management of cane fields. Proceedings Australian Society of Sugar Cane Technologists 
1996, 119–124. 

Raymond OL (2018) Australian Geological Provinces 2018.01 edition. Geoscience Australia, 
Canberra. Australia G, 
(https://ecat.ga.gov.au/geonetwork/srv/eng/catalog.search#/metadata/116823). 

Robins JB, Halliday IA, Staunton-Smith J, Mayer DG and Sellin MJ (2005) Freshwater-flow 
requirements of estuarine fisheries in tropical Australia: a review of the state of knowledge 
and application of a suggested approach. Marine and Freshwater Research 56, 343–360. 

Ross A and Hasnain S (2018) Factors affecting the cost of managed aquifer recharge (MAR) 
schemes. Sustainable Water Resources Management. DOI: 10.1007/s40899-017-0210-8. 

Scarborough VL and Gallopin G (1991) A water storage adaptation in the Maya Lowlands. Science 
251(4), 658–662. DOI:10.1126/science.251.4994.658. 

Schnitter NJ (1994) A history of dams: the useful pyramids. AA Balkema, Rotterdam, Brookfield. 


Merrin L, Stratford D, Kenyon R, Pritchard J, Linke S, Ponce Reyes R, Buckworth R, Castellazzi P, 
Costin B, Deng R, Gannon R, Gao S, Gilbey S, Lachish S, McGinness H and Waltham N (2024) 
Ecological assets of the Southern Gulf catchments to inform water resource assessments. A 
technical report from the CSIRO Southern Gulf Water Resource Assessment for the National 
Water Grid. CSIRO, Australia. 

Thomas M, Philip S, Zund P, Stockmann U, Hill J, Gregory L, Watson I and Thomas E (2024) Soils 
and land suitability for the Southern Gulf catchments. A technical report from the CSIRO 
Southern Gulf Water Resource Assessment for the National Water Grid. CSIRO, Australia. 

Tomkins K (2013) Estimated sediment infilling rates for dams in northern Australia based on a 
review of previous literature. A technical report to the Australian Government from the 
CSIRO Flinders and Gilbert Agricultural Resource Assessment, part of the North Queensland 
Irrigated Agriculture Strategy. CSIRO Water for a Healthy Country and Sustainable 
Agriculture flagships, Australia. 

Vanderzalm JL, Page DW, Gonzalez D, Barry KE, Dillon PJ, Taylor AR, Dawes WR, Cui T and 
Knapton A (2018) Assessment of managed aquifer recharge (MAR) opportunities in the 
Fitzroy, Darwin and Mitchell catchments. A technical report to the Australian Government 
from the CSIRO Northern Australia Water Resource Assessment, part of the National Water 
Infrastructure Development Fund: Water Resource Assessments. CSIRO, Australia. 

Waltham N, Burrows D, Butler B, Wallace J, Thomas C, James C and Brodie J (2013) Waterhole 
ecology in the Flinders and Gilbert catchments. A technical report to the Australian 
Government from the CSIRO Flinders and Gilbert Agricultural Resource Assessment, part of 
the North Queensland Irrigated Agriculture Strategy. CSIRO Water for a Healthy Country and 
Sustainable Agriculture flagships, Canberra, Australia. Viewed 7 February 2017, Hyperlink to: Waterhole ecology in the Flinders and Gilbert catchments
. 

Wasson RJ (1994) Annual and decadal variation of sediment yield in Australia, and some global 
comparisons. Variability in stream erosion and sediment transport, Proceedings of the 
Canberra Symposium. IAHS Publ. no. 224, 269–279. 

Wood M, Wang Q and Bethune M (2007) An economic analysis of conversion from border-check 
to centre-pivot irrigation on dairy farms in the Murray dairy region. Irrigation Science 26(1), 
9–20. 

Yang A, Petheram C, Marvanek S, Baynes F, Rogers L, Ponce Reyes R, Zund P, Seo L, Hughes J, 
Gibbs M, Wilson PR, Philip S and Barber M (2024) Assessment of surface water storage 
options in the Victoria and Southern Gulf catchments. A technical report from the CSIRO 
Victoria River and Southern Gulf Water Resource Assessments for the National Water Grid. 
CSIRO Australia. 




 

Part IV Economics of 
development and 
accompanying risks 

Chapters 6 and 7 describe economic opportunities for water development in the Southern Gulf 
catchments, and the accompanying constraints and risks: 

• economic opportunities and constraints (Chapter 6) 
• a range of risks to development (Chapter 7). 



Agricultural production in the Southern Gulf catchments is 
dominated by extensive grazing of beef cattle, valued at $240 
million in 2020–21 and covers about 77% of the study area. 

Photo: CSIRO – Nathan Dyer 



6 Overview of economic opportunities and 
constraints in the Southern Gulf catchments 

Authors: Chris Stokes, Shokhrukh Jalilov, Diane Jarvis 

 
Chapter 6 examines the types of opportunities for the development of irrigated agriculture in the 
catchment of the Southern Gulf riversFigure 6-1). 
1, that is Settlement Creek, Gregory—Nicholson River and 
Leichhardt River, the Morning Inlet catchments and the Wellesley island groups, that are most 
likely to be financially viable. The chapter considers the costs of building the required 
infrastructure (both within the scheme and beyond), the financial viability of various types of 
schemes (including lessons learned from past large dam developments in Australia) and the 
regional economic impacts (the direct and flow-on effects for businesses across the catchment) 
(

1 Only those islands greater than 1000 ha are mapped. 

 

Figure 6-1 Schematic diagram of key components affecting the commercial viability of a potential greenfield 
irrigation development 

"\\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\10_Reporting\1_All\9_Graphics_artist\3_Vic and SoG\C Bruce Vic CR Chp6_8_2024.jpg"
The chapter focuses on the costs and benefits that are the subject of normal market transactions, 
but it does not provide a full economic analysis. Commercial factors are likely to be among the 
most important criteria in deciding between potential development opportunities. Options clearly 
identifiable at the pre-feasibility stage as not being commercially viable could be deprioritised. 


More-detailed and project-specific agronomic, ecological, social, cultural and regulatory 
assessments could then focus on those opportunities identified as showing the most commercial 
promise. The non-market impacts and risks associated with any financially viable development 
opportunities, discussed in Chapter 7, must also be considered. 

6.1 Summary 

6.1.1 Key findings 

Scheme-scale financial viability 

New investment in irrigation development in the Southern Gulf catchments would depend on 
finding viable combinations of low-cost water sources, low-cost farming development 
opportunities, and high-productivity farms; finding opportunities for reducing cropping costs and 
attracting price premiums for produce; and managing a wide range of risks. 

Financial analyses have indicated that large dams in the Southern Gulf catchments are unlikely to 
be viable if public investors target full cost recovery at a 7% internal rate of return (IRR) and do not 
provide assistance, which would make water from the most cost-effective dam sites too expensive 
for irrigators. However, large dams could be marginally viable if public investors accepted a 3% 
IRR. On-farm water sources provide better prospects than large dams: where sufficiently cheap 
water development opportunities can be found, they could support viable broadacre farms and 
horticulture with low development costs. Horticulture with high development costs (e.g. fruit 
orchards) in the Southern Gulf catchments would be more challenging unless farm financial 
performance could be boosted by (i) finding niche opportunities for premium produce prices, (ii) 
making savings in production and marketing costs, and/or (iii) obtaining high yields. 

Farm performance can be affected by a number of risks, including water reliability, climate 
variability, price fluctuations, and the need to adapt farming practices to new locations. Setbacks 
that occur soon after an irrigation scheme has been established have the largest effect on scheme 
viability. There is a strong incentive for using well-proven crops and technologies when starting 
any new irrigation development, and for being thoroughly prepared for those agronomic risks of 
establishing new farmland that can be anticipated. Risks that cannot be avoided must be 
managed, mitigated where possible, and accounted for when determining the realistic returns 
that may be expected from a scheme and the capital buffers that would be required. 

Cost–benefit analysis of large public dams 

A review of recent large public dams built in Australia has highlighted some areas where cost–
benefit analyses (CBAs) for water infrastructure projects that could be improved upon, particularly 
the need for more-realistic forecasting of the demand for water. This chapter provides information 
for benchmarking a number of the processes commonly used in such CBAs, including demand 
forecasting, which can be used to check when proposals for new dams are being unrealistically 
optimistic (or pessimistic). 

Regional economic impacts 

Any new irrigated agriculture development and its supporting infrastructure will have knock-on 
benefits to the regional economy beyond direct economic growth from the new farms and 


construction. The initial construction phase of a new irrigation development in the Southern Gulf 
catchments could provide an additional approximately $1.1 million of indirect regional benefits, 
over and above the direct benefits, for each million dollars spent on construction within the local 
region. The ongoing production phase of a new irrigation development could provide an additional 
(approximately) $0.46 to $1.82 million of indirect regional benefits for each million dollars of 
direct benefits from the increased agricultural activity (gross revenue), depending on the type of 
agricultural industry. The indirect regional benefits would be reduced if some of the extra 
expenditure generated by a new development was leaked to outside the catchment. Each 
$100 million increase in agricultural activity could create approximately 100 to 852 jobs. 

6.2 Introduction 

Large new infrastructure projects in Australia are expected to be increasingly accountable and 
transparent. This trend extends to the planning and building of new water infrastructure, and the 
way water resources are managed and priced (e.g. Infrastructure Australia, 2021a, 2021b; NWGA, 
2022, 2023), and includes greater scrutiny of the costs and benefits of potential large new public 
dams. The difficulty in accurately estimating costs and the chance of incurring unanticipated 
expenses during construction, and of not meeting the projected water demands and achieving 
revenue trajectories when completed, put the viability of developments at risk if they are not 
thoroughly planned and assessed. For example, in a global review of dam-based megaprojects, 
Ansar et al. (2014) found that the forecast costs were systematically biased downwards, with 
three-quarters of projects running over budget and the mean of the actual costs being almost 
double the initial estimates. This is typical for most types of large infrastructure projects, not just 
dams (see review in Section 6.4.1). 

Ultimately, economic factors are likely to be among the most important criteria in deciding the 
scale and types of potential development opportunities in the Southern Gulf catchments. An 
assessment of 13 agricultural developments in northern Australia found that, while the natural 
environments were challenging for agriculture, the most important factors determining the 
viability of developments were management, planning and finances (Ash et al., 2014). At the pre-
feasibility stage, options that can be clearly identified as not being financially viable could be 
deprioritised. The expensive, more-detailed and project-specific agronomic, ecological, social, 
cultural and regulatory assessments could then focus on the more promising opportunities. This 
chapter aims to assist future planning and evaluation of investments in new irrigated agriculture 
developments by highlighting the types of projects that are more likely to be viable, and 
quantifying the costs, benefits and risks involved. It provides a generic information resource that is 
broadly applicable to a variety of irrigated agriculture development opportunities but does not 
examine any specific options in detail. The results are presented in a way that allows readers to 
identify the costs, risks, and farm productivity values specific to the project opportunities in which 
they are interested, to evaluate their likely financial viability. The information also provides a set 
of benchmarks for establishing realistic assumptions and the thresholds of financial performance 
required for water and farm developments, individually and in combination, to be financially 
viable. 

This chapter builds on earlier material in Chapter 4 (assessing the viability of new irrigated 
agriculture opportunities in the Southern Gulf catchments at the enterprise level) and in Chapter 5 


(assessing the opportunities for developing water sources to support those farms). Section 

Rather than analysing the cost–benefit of specific irrigation scheme proposals, this chapter 
presents generic tables for evaluating multiple alternative development configurations, providing 
the threshold farm gross margins and water costs and pricing that would be required in order to 
cover infrastructure costs. These tables serve as tools that allow users to answer their own 
questions about agricultural land and water development. Examples of the questions that can be 
asked, and which tables provide the answers, are given in Table 6-1. 

Table 6-1 Types of questions that users can answer using the tools in this chapter 

For each question, the relevant table number is given, together with an example answer for a specific development 
scenario. More questions can be answered with each tool by swapping around the factors that are known and the 
factor being estimated. (All initial estimates assume farm performance is 100% in all years, i.e. before accounting for 
risks. See Table 6-3 for the supporting generalised assumptions.) 

QUESTION (WITH EXAMPLE ANSWER) 

RELEVANT TABLE 

1) How much can various types of farms afford to pay per ML of water they use? 

Table 6-4 

A broadacre farm with a gross margin (GM) of $4000/ha and water consumption of 8 ML/ha could afford to 
pay $135/ML while achieving a 10% internal rate of return (IRR). 

 

2) How much would the operator of a large off-farm dam have to charge for water? 

Table 6-6 

If off-farm water infrastructure had a capital cost of $5000 for each ML/y supply capacity (yield) at the dam 
wall, the (public) water supplier would have to charge $537 for each ML to cover its costs (at a 7% target 
IRR). 

 

3) For an on-farm dam with a known development cost, what is the equivalent $/ML price of water? 

Table 6-8 

If a farm dam had a capital development cost of $1500 for each ML/y supply capacity (yield), water could be 
purchasable at a cost of $190 for each ML (given a 10% target IRR). 

 

4) (a) What farm GM would be required in order to fully cover the costs of an off-farm dam? 

(b) What proportion of the costs of off-farm water infrastructure could farms cover? 

Table 6-5 

If off-farm infrastructure had a capital cost of $50,000/ha to build, broadacre farms would need to generate 
a GM of $5701/ha in order to fully cover the water supply costs (while meeting a target 7% IRR for the water 
supplier (public investor) and a 10% IRR for the irrigator (private investor)). 

With the same target IRRs, a broadacre farm with a GM of $4000/ha could contribute the equivalent of 
$20,000 to $30,000 per ha towards the capital costs of building the same $50,000/ha dam (~50% of the full 
costs of building and operating that infrastructure). 

 

5) What GM would be required in order to cover the costs of developing a new farm, including a dam or 
bores? 

Table 6-7 

A horticultural farm with low overheads ($1500/ha) that cost $40,000/ha to develop (e.g. $30,000/ha to 
establish the farm and $10,000/ha to build the on-farm water supply for irrigating it) would require a GM of 
$6702/ha to attain a 10% IRR. 

 




QUESTION (WITH EXAMPLE ANSWER) 

RELEVANT TABLE 

6) How would risks associated with water reliability affect the farm GMs above? 

Table 6-9 

If an on-farm dam could fully irrigate the farm in 70% of years and could irrigate 50% of the farm in the 
remaining years, all farm GMs in the answers above would need to be multiplied by 1.18 (i.e. would be 18% 
higher), and the price irrigators could afford to pay for water would need to be divided by 1.18. 

For example, in Q4, the GM required in order to cover the costs of the farm development would increase 
from $5701/ha to $6727/ha after accounting for the risks of water reliability. 



7) How would the risks associated with ‘learning’ (initial farm underperformance) affect estimates?

Table 6-11 

If a farm with a 10% target IRR achieved a GM that was 50% of its full potential in the first year, and 
gradually improved to achieve its full potential over 10 years, then the GMs above would need to be 
multiplied by a factor of 1.26 (i.e. would be 26% higher). 

For example, in Q6, the required farm GM would increase to $8476/ha after accounting for the risks of both 
water reliability and learning (a combined 49% higher than the value before accounting for risks). 





6.3 Balancing scheme-scale costs and benefits 

Designing a new irrigation development in the Southern Gulf catchments would require balancing 
three key determinants of irrigation scheme financial performance to find combinations that 
might collectively constitute a viable investment. The determinants are: 


1.farm financial performance (relative to development costs and water use) (Chapter 4)
2.capital cost of development, for both water resources and farms (Chapter 5 and Section 6.3.1)
3.risks (and the associated required level of investment return) (Section 6.3.5).


The determinants considered have been limited to those with greater certainty and/or lower 
sensitivity, so that the results can be applied to a wide range of potential developments. 

A key finding of the irrigation scheme financial analyses is that no single factor within the above 
list is likely to be able to provide a silver bullet for meeting the substantial challenge of designing a 
commercially viable new irrigation scheme. Balancing the benefits to meet costs in order to 
identify viable investments would likely require contributions from each of the above factors and 
careful selection to piece together a workable combination. This section provides background 
information on the analysis approach used, to help readers understand how these factors 
influence irrigation scheme financial performance. 

6.3.1 Approach and terminology 

Scheme financial evaluations use a discounted cashflow framework to evaluate the commercial 
viability of irrigation developments. The framework, detailed in the companion technical report on 
agricultural viability and socio-economics (Webster et al., 2024), is intended to provide a purely 
financial evaluation of the conditions required to produce an acceptable return from an investor’s 
perspective. It is not a full economic evaluation of the costs and benefits to other industries, nor 
does it consider ‘unpriced’ impacts that are not the subject of normal market transactions, or the 
equity of how costs and benefits are distributed. For the discussion that follows, the costs and 
benefits of an irrigation scheme were taken to include all those from the development of the land 
and water resources to the point of sale for farm produce. 

This section explains the terminology and standard assumptions used. 


A ‘discounted cashflow analysis’ considers the lifetime of costs and benefits following capital 
investment in a new project. Costs and benefits that occur at various times are expressed in 
constant real dollars (December 2023 Australian dollars), with a discount rate being applied to 
streams of costs and benefits. 

The ‘discount rate’ is the percentage by which future costs and benefits are discounted each year 
(compounded) to convert them to their equivalent present value. 

For an entire project, the ‘net present value’ (NPV) can be calculated by subtracting the present 
value of the stream of all costs from the present value of the stream of all benefits. The ‘benefit-
to-cost ratio’ (BCR) of a project is the present value of all the benefits of a project divided by the 
present value of all the costs involved in achieving those benefits. To be commercially viable (at 
the nominated discount rate), a project would require an NPV that is greater than zero (in which 
case the BCR would be greater than one). 

The IRR is the discount rate at which the NPV is zero (and the BCR is 1). For a project to be 
considered commercially viable, it needs to meet its target IRR, and the NPV has to be greater 
than zero at a discount rate appropriate to the risk profile of the development and alternative 
investment opportunities available to investors. A target IRR of 7% is typically used when 
evaluating large public investments (with the sensitivity analysis set at 3% and 10%) (Infrastructure 
Australia, 2021b). Private agricultural developers usually target an IRR of 10% or more (to 
compensate for the investment risks involved). A back-calculation approach is used in the tables 
below to present the threshold GMs and water prices that would be required in order for investors 
to achieve specified target IRRs (the NPV would be equivalent to zero at these discount rates). 

The ‘project evaluation periods’ used in this chapter matched the ‘life spans’ of the main 
infrastructure assets: 100 years for large off-farm dams and 40 years for on-farm developments. 
To simplify the tracking of asset replacements, four categories of life spans were used: 15 and 
40 years for farms and 25 and 100 years for off-farm infrastructure. It was assumed that the 
shorter-life-span assets would be replaced at the end of their life, and that their costs would have 
been accounted for in full by the actual year of their replacement. At the end of the evaluation 
period, a ‘residual value’ was calculated to account for any shorter-life-span assets that have not 
reached the end of their working life. Residual values were calculated as the proportional asset life 
remaining multiplied by the original asset price. 

The ‘capital costs’ of infrastructure were assumed to be the costs at completion (accounted for in 
full in the year of delivery), such that the assets commenced operations the following year. In 
some cases, the costs of developing the farmland and setting up the buildings and equipment 
were considered separately from the costs of the water source, so that various water source 
options could be compared on a like-for-like basis. Where an off-farm water source was used, the 
separate investor in that water source would receive payments for water at a price that the 
irrigator could afford to pay. 

The main ‘costs for operating’ a large dam and the associated water distribution infrastructure are 
(i)fixed costs for administering and maintaining the infrastructure, expressed here as percentageof the original capital cost, and (ii) variable costs associated with pumping water into distributionchannels.


At the farm scale, fixed overhead costs are incurred each year, whether or not a crop is planted in 
a particular field that year. ‘Fixed costs’ are dominated by the fixed component of labour costs, 
but also include maintenance, insurance, professional services, and registrations. An additional 
allowance is made for annual operation and maintenance (O&M), budgeted at 1% of the original 
capital value of all assets (with an additional variable component in maintenance costs when 
machinery is used for cropping operations). 

A ‘farm annual gross margin’ (GM) is the difference between the gross income from crop sales and 
the variable costs of growing a crop each year. ‘Net farm revenue’ is calculated by subtracting the 
fixed overhead costs from the GM. ‘Variable costs’ vary in proportion to the area of land planted, 
the amount of crop harvested and/or the amount of water and other inputs applied. Farm GMs 
can vary substantially within and between locations, as described in Chapter 4. The GMs 
presented here are the values obtained before subtracting the variable costs of supplying water to 
farms; these water supply costs are, instead, accounted for in the capital costs of developing water 
resources. (The equivalent unit costs of supplying each ML of water are presented separately 
below.) 

The CBA analyses first considered the case of irrigation schemes built around public investment in 
a large off-farm dam in the Southern Gulf catchments and then considered the case developments 
using ‘on-farm’ dams and bores. 

Cost and benefit streams, totalled across the scheme, were tracked as separate components, 
allowing for both on-farm and off-farm sources of new water development. For farms, these 
streams were: (i) the capital costs of land development, farm buildings and equipment (including 
replacement costs and residual values), (ii) the fixed overhead costs, applied to the full area of 
developed farmland, and (iii) the total farm GM (across all farms in the scheme), applied to the 
mean proportion of land in production each year. If an ‘on-farm water source’ was being 
considered, then those costs were added to the farm costs. Farm developers were treated as 
private investors who would seek a commercial return. 

When an ‘off-farm water source’ (large dam >25 GL/year) was evaluated, its investor was treated 
as a separate public investor to whom payment was made by farmers for water supplied (which 
served as an additional stream of costs for farmers, and a stream of benefits for the water 
supplier, at their respective target IRRs). For the public off-farm developer, the streams of costs 
were: (i) the capital costs of developing the water and associated enabling infrastructure 
(including replacement costs and residual values), and (ii) the costs of maintaining and operating 
those assets. 

Threshold gross margins and water pricing to achieve target internal rate of return 

New irrigation schemes in the Southern Gulf catchments would be costly to develop, so many 
technically feasible options are unlikely to be profitable at the returns and over the time periods 
expected by many investors. The results presented below suggest it would be difficult for any 
farming options to fully cover the costs of a large off-farm dam development. However, there are 
greater prospects of viable developments using on-farm sources of water for broadacre and cost-
efficient horticulture. 

The costs of developing water and land resources for a new irrigation development vary widely 
depending on a range of case-specific factors that are dealt with in other parts of this Assessment. 


These factors include the type and nature of the water source, type of water storage, geology, 
topography, soil characteristics, water distribution system, type of irrigation system, type of crop 
to be grown, local climate, land preparation requirements, and level to which infrastructure is 
engineered. 

The financial analyses, therefore, have taken a generic approach in exploring the consequences for 
the development costs of this variation, and other key factors that determine whether or not an 
irrigation scheme would be viable (e.g. farm performance and the level of returns sought by 
investors). The analyses used the discounted cashflow framework described above to back-
calculate and fit the water prices and farm GMs that would be required for respective public (off-
farm) and private investors (irrigators) to achieve their target IRRs. The results are summarised in 
tables showing the thresholds that must be met for a particular combination of water 
development and farm development options to meet the investor’s target returns. The tables 
allow viable pairings to be identified based on either threshold costs of water or required farm 
GMs. Financial viability for these threshold values was defined and calculated as investors 
achieving their target IRR (or, equivalently, that the investment would have an NPV of zero and a 
BCR of one at the target discount rate). 

Assumptions 

The first analyses considered the case of irrigation schemes built around public investment in a 
large off-farm dam in the Southern Gulf catchments. The analyses then considered the case of 
developments using on-farm dams and bores. To keep the results as relevant as possible to a wide 
range of different development options and configurations, the analyses here do not assume the 
scale at which a water development would be undertaken. Instead, all costs are expressed per 
hectare of irrigated farmland and per ML per year of water supply capacity, facilitating 
comparisons between scenarios (which can differ substantially in size). To illustrate how this 
slightly abstract generic approach can be applied to specific development projects, three worked 
examples show the indicative off-farm infrastructure costs that would be involved in development 
of the most cost-effective dam sites in close proximity to soils suitable for irrigated agriculture 
identified in the Southern Gulf catchments (Table 6-2). 

Table 6-2 Indicative capital costs for developing three irrigation schemes based on the most cost-effective dam sites 
identified in the Southern Gulf catchments 

FSL = full supply level. 

For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au







To enhance like-for-like comparisons across the various development scenarios, a set of standard 
assumptions have been made about the breakdown of development costs (by life span) and 
associated ongoing operating costs (Table 6-3). Three indicative types of farming enterprise 
represent different levels of capital investment, associated with the intensity of production and 
the extent to which farming operations are performed on-farm or outsourced (Table 6-3). The 
capital costs and fixed costs are higher for horticulture than for broadacre farming, but the more 
expensive irrigation systems used (such as drippers) apply water more precisely and efficiently to 
crops. The indicative ‘Broadacre’ farm could, for example, represent hay or cotton farming using 
furrow irrigation on heavier clay soils. The indicative capital-intensive ‘Horticulture-H’ farm could, 
for example, represent high-value fruit-tree orchards with high standard on-farm packing and cold 
room facilities, and include accommodation for seasonal workers travelling to very remote 
Southern Gulf catchments farms. The indicative less-capital-intensive ‘Horticulture-L’ farm option 
could, for example, represent a row crop, such as melons, with packing directly to bins and use of 
off-farm accommodation for seasonal workers (which reduces the upfront capital cost of 
establishing the farm, but increases the ongoing costs for outsourced services, which reduces 
farm GMs). 
Table 6-3 Assumed indicative capital and operating costs for new off- and on-farm irrigation infrastructure 
Three types of farming enterprise represent a range of increasing intensity, value and cost of production. Indicative 
base capital costs for establishing new farms (excluding water costs) allow on- and off-farm water sources to be added 
and compared on an equal basis. Annual operation and maintenance (O&M) costs are expressed as a percentage of 
the capital costs of assets. The Horticulture-H farm, with higher development costs, includes on-farm packing facilities, 
cold storage, and accommodation for seasonal workers. The Horticulture-L farm, with lower development costs, does 
not include these assets and would have to outsource these services if required (reducing the farm gross margin). IRR 
= internal rate of return. 

SCHEME 
COMPONENT 

ITEM 





VALUE 



UNIT 

O&M COST 
(% capital 
cost/y) 

Off-farm infrastructure development capital and operating costs (large dam and enabling infrastructure) 

Capital costs 

Total capital costs 
(split by life span below) 

Indicative >50,000 
(analysed range: 20,000 to 150,000) 

$/ha 





Longer life span infrastructure 
(100 y) 



85 



% 

0.4 



Shorter-life-span 
infrastructure (40 y) 



15 



% 

1.6 

Operating costs 

O&M (by life span categories) 



% capital cost 



$/ha/y 





Off-farm water source pumping costs 

~2 (additional) 

$/ML/m 



Target IRR 

Base (with sensitivity range) 

7 



% 



Farm development capital and operating costs 

Broadacre 

Horticulture-L 
(low capital) 

Horticulture-H 
(high capital) 





Capital costs 

Base (excluding water source) 

9,000 

25,000 

70,000 

$/ha 





Water source (on- or off-farm) 

Indicative >4,000 
(analysed range: 3,000 to 15,000) 

$/ha 





Longer-life-span infrastructure 
(40 y) 

50 

50 

50 

% 

1.0 




SCHEME 
COMPONENT 

ITEM 





VALUE 



UNIT 

O&M COST 
(% capital 
cost/y) 



Shorter-life-span 
infrastructure (15 y) 

50 

50 

50 

% 

1.0 

Operating costs 

O&M (by life-span categories) 

% capital cost 

$/ha/y 





Farm water source pumping costs 

~2 (additional) 

$/ML/m 





Fixed costs 



600 

1,500 

6,500 

$/ha/y 



Water use 

Crop water use (before losses) 

6 

6 

6 

ML/ha/y 





On-farm water use efficiency 

70 

90 

90 

% 



Gross margin 

Indicative gross margin 

4,000 

7,000 

11,000 

$/ha/y 



Target IRR 

Base (with sensitivity range) 

10 

10 

10 

% 







For consistency, all costs of delivering water to the farm at the level of the soil surface are treated 
as the costs of the water source (so the costs of the various water source options can be compared 
on a like-for-like basis). Subsequent farm pumping costs of distributing and applying the supplied 
water to crops are treated as part of the variable costs of growing crops and are already accounted 
for in the crop GMs presented in Chapter 4. The pumping costs for the water supplier are highly 
situation-specific for the various water sources. In particular, these pumping costs are affected by 
the elevation of the water source relative to the point of distribution to the farm: for example, the 
height water needs to be pumped from a weir to a distribution channel, or from a farm dam to a 
field; or the dynamic head required to lift bore water to the field surface. For this reason, water 
source pumping costs have not been included in the summary tables of water pricing, but should 
be added separately as required at a cost of approximately $2 per ML per m dynamic head. This is 
mainly a consideration for groundwater bores, but also applies when water needs to be lifted from 
rivers or irrigation channels. For more information on water infrastructure costs, see Chapter 5 
(and the companion technical reports referenced there). For more information on crop GMs, see 
Chapter 4 (and the companion technical reports referenced there). 
The analyses presented below consider (i) the case of irrigation schemes built around a large dam 
and its associated supporting off-farm infrastructure (Section 6.3.3); (ii) the case of self-contained, 
modular farm developments with their own on-farm source of water (Section 6.3.4). For both 
cases, the water price that irrigators can afford to pay provides a useful common point of 
reference for identifying the most affordable water sources for various types of farm 
developments (Section 6.3.2). The initial analyses assumed that all farmland was in full production 
and performed at 100% of its potential (and assumed 100% reliable water supplies) from the start 
of the development. Section 6.3.5 provides a set of adjustment factors that quantify the risks of 
various sources of underperformance that can be anticipated. 

6.3.2 Price irrigators can afford to pay for a new water source 

Table 6-4 shows the price that the three different types of farms could afford to pay for water, 
while meeting a target 10% IRR, for three different levels of farm water use and productivity. For 
prices to be sustained at this level throughout the life of the water source, the associated farm GM 
(in the first column of Table 6-4) would also need to be maintained over this period. The table is, 








therefore, most useful when assessing the long-term price that can be sustained to pay off long-
lived water infrastructure (rather than temporary spikes in farm GMs during runs of favourable 
years). 
The lowest GM in the first column of Table 6-4 for each farm type is the value below which the 
farm would not be viable, even if water was free. This does not necessarily mean that such GMs 
could readily be achieved in practice: for the capital-intensive Horticulture-H farm, in particular, it 
would be challenging in the Southern Gulf catchments to reach the $17,000 per ha per year GM to 
cover the farm’s other costs, even before considering the costs of water. 
Table 6-4 Price irrigators can afford to pay for water, based on the type of farm, the farm water use and the farm 
annual gross margin (GM), while meeting a target 10% internal rate of return (IRR) 
Analyses assume water volumes are measured on delivery to the farm gate or surface: pumping costs involved in getting 
water to the farmland surface would be an additional cost of supplying the water (indicatively $2 per ML per m 
dynamic head), while pumping costs in distributing and applying the water to the crop are considered part of the 
variable costs included in the GM. Indicative GMs that the three types of farms could attain in the Southern Gulf 
catchments are $4000 and $7000 per ha per year for Broadacre and Horticulture-L farms, respectively (blue-shaded 
rows), and $11,000 per ha per year for Horticulture-H (Table 6-3, Chapter 4). Note that the Horticulture-H farm cannot 
pay anything for water until it achieves a GM above $17,000 per ha per year. 

GROSS MARGIN 

PRICE IRRIGATORS CAN AFFORD TO PAY 

($/ha/y) 

($/ML at farm gate/surface) 



Farm water use (ML/ha, including on-farm distribution and application losses) 



4 

5 

6 

7 

8 

9 

10 

12 



Broadacre ($9,000/ha development costs, $600/ha/y fixed costs, 70% on-farm efficiency) 

2,000 

25 

20 

17 

14 

12 

11 

10 

8 

2,500 

86 

69 

57 

49 

43 

38 

34 

29 

3,000 

147 

118 

98 

84 

74 

65 

59 

49 

3,500 

209 

167 

139 

119 

104 

93 

83 

70 

4,000 

270 

216 

180 

154 

135 

120 

108 

90 

5,000 

392 

314 

262 

224 

196 

174 

157 

131 



Horticulture-L ($25,000/ha development costs, $1,500/ha/y fixed costs, 90% on-farm efficiency) 

5,000 

39 

31 

26 

22 

19 

17 

16 

13 

6,000 

241 

193 

161 

138 

121 

107 

97 

80 

7,000 

444 

355 

296 

254 

222 

197 

178 

148 

8,000 

646 

517 

431 

369 

323 

287 

259 

215 

10,000 

1051 

841 

701 

601 

526 

467 

421 

350 

12,000 

1456 

1165 

971 

832 

728 

647 

583 

485 



Horticulture-H ($70,000/ha development costs, $6,500/ha/y fixed costs, 90% on-farm efficiency) 

17,000 

203 

162 

135 

116 

101 

90 

81 

68 

20,000 

810 

648 

540 

463 

405 

360 

324 

270 

25,000 

1823 

1458 

1215 

1042 

911 

810 

729 

608 

30,000 

2835 

2268 

1890 

1620 

1418 

1260 

1134 

945 

40,000 

4860 

3888 

3240 

2777 

2430 

2160 

1944 

1620 
































These water prices are likely to be most useful for public investors in large dams, because the 
sequencing of development creates asymmetric risks between the water supplier and the 
irrigators. Irrespective of the planned water pricing for a dam project, once the dam is built, 
irrigators have the choice of whether to develop new farms; they are unlikely to act to their own 
detriment by making an investment if they cannot do so at a water price that will allow them to 
obtain a commercial rate of return. These water prices, together with estimates of likely attainable 
farm GMs (available in Chapter 4), provide a useful benchmark for checking assumptions about 
any potential public dam developments in the Southern Gulf catchments. 

For on-farm water sources, these water prices can assist in identifying water development options 
that cropping operations could reasonably be expected to afford. The tables in the next sections 
allow comparisons of irrigation development options by converting the capital costs of developing 
on- and off-farm water sources to volumetric costs ($/ML supplied). All water prices are based on 
volumes supplied to the farm gate or surface (after losses in transit) per metered ML supplied. 

6.3.3 Financial targets required in order to cover full costs of large, off-farm dams 





The first generic assessment considered the case of public investment in a large dam in the 
Southern Gulf catchments and whether the costs of that development could be covered by water 
payments from irrigators (priced at their capacity to pay). The public costs of development include 
the cost of the dam and water distribution, and of any other supporting infrastructure required. 
Costs are standardised per unit of farmland developed, noting that for the same outlay, a smaller 
area could be developed for a crop with a higher water use (i.e. the water development costs per 
hectare would be higher). 
Target farm gross margins for off-farm public water infrastructure 
Table 6-5shows what farm annual GMs would be required for various costs of water 
infrastructure development at the public investors’ target IRR. As expected, higher farm GMs are 
required in order to cover higher capital costs and/or to attain a higher target IRR. The tables in 
this section can be used to assess whether water development opportunities and farming 
opportunities in the Southern Gulf catchments are likely to combine in financially viable ways. 
Indicative farm GMs that could be achieved in the Southern Gulf catchments are approximately 
$4000, $7000 and $11,000 per ha per year for Broadacre, less-capital-intensive Horticulture-L 
(including penalising GMs if outsourcing occurs) and capital-intensive Horticulture-H, respectively 
(Table 6-3). A dam and supporting infrastructure would likely require at least $50,000/ha of capital 
investment (Table 6-2). None of the three farming types is likely to be viable at these farm GMs 
and water development costs (at a 7% target IRR for the public investor). However, Broadacre and 
Horticulture-L farming might be marginally viable at a 3% target IRR for the public investor. 
Broadacre and lower-cost Horticulture-L could both achieve a target 10% IRR for the farm 
investments while contributing $20,000 to $30,000 per ha (40%–60%) towards the cost of a dam 
that cost $50,000/ha to build (including enabling infrastructure and ongoing O&M costs). That is a 
higher proportion of costs than irrigators have historically contributed towards irrigation 
schemes in some other parts of Australia (typically approximately a quarter of capital costs 
(Vanderbyl, 2021)), and would involve a decision by the Australian Government and the NT and 
Queensland governments based on their expectations, priorities, and investment criteria. 
390 | Water resource assessment for the Southern Gulf catchments 






Table 6-5 Farm gross margins (GMs) required in order to cover the costs of off-farm water infrastructure (at the 
supplier’s target internal rate of return (IRR)) 
Assumes 100% farm performance on all farmland in all years, once construction is complete. Costs of supplying water 
to farms are consistently treated as costs of water source development (and not part of the farm GM calculation). Risk 
adjustment multipliers are provided in Section 6.3.5. Blue-shaded cells indicate the capital costs that could be 
afforded by farms with GMs of $4000 (Broadacre), $7000 (Horticulture-L) and $11,000 (Horticulture-H) per ha per 
year. Blue-shaded column headers indicate the most cost-effective dam development options in the Southern Gulf 
catchments (Table 6-2). 

TARGET IRR 

FARM GROSS MARGIN REQUIRED IN ORDER TO PAY FOR OFF-FARM WATER INFRASTRUCTURE 

(%) 

($/ha/y) 



Total capital costs of off-farm water infrastructure ($/ha) 



20,000 

30,000 

40,000 

50,000 

70,000 

100,000 

125,000 

150,000 



Broadacre ($9,000/ha development costs, $600/ha/y fixed costs, 70% on-farm efficiency) 

3 

2,604 

3,016 

3,428 

3,840 

4,664 

5,900 

6,930 

7,960 

5 

2,977 

3,569 

4,160 

4,751 

5,933 

7,707 

9,185 

10,663 

7 

3,359 

4,139 

4,920 

5,701 

7,263 

9,605 

11,558 

13,510 

10 

3,941 

5,013 

6,085 

7,157 

9,301 

12,516 

15,196 

17,876 

12 

4,333 

5,601 

6,869 

8,137 

10,673 

14,478 

17,648 

20,818 



Horticulture-L ($25,000/ha development costs, $1,500/ha/y fixed costs, 90% on-farm efficiency) 

3 

5,584 

5,996 

6,408 

6,820 

7,645 

8,881 

9,911 

10,941 

5 

5,985 

6,576 

7,167 

7,759 

8,941 

10,715 

12,193 

13,671 

7 

6,370 

7,150 

7,931 

8,712 

10,274 

12,616 

14,569 

16,521 

10 

6,952 

8,024 

9,096 

10,168 

12,312 

15,528 

18,208 

20,887 

12 

7,345 

8,613 

9,881 

11,149 

13,685 

17,489 

20,659 

23,829 



Horticulture-H ($70,000/ha development costs, $6,500/ha/y fixed costs, 90% on-farm efficiency) 

3 

16,618 

17,068 

17,518 

17,967 

18,867 

20,217 

21,342 

22,467 

5 

17,164 

17,789 

18,413 

19,038 

20,288 

22,162 

23,724 

25,286 

7 

17,610 

18,416 

19,222 

20,027 

21,638 

24,055 

26,070 

28,084 

10 

18,215 

19,301 

20,387 

21,472 

23,644 

26,901 

29,615 

32,330 

12 

18,607 

19,884 

21,161 

22,438 

24,992 

28,823 

32,015 

35,207 





Target water pricing for off-farm public water infrastructure 
Table 6-6 shows the price that a public investor in off-farm water infrastructure would have to 
charge to fully cover the costs of development of off-farm water infrastructure, expressed per unit 
of supply capacity at the dam wall. Pricing assumes that the full supply of water (i.e. reservoir 
yield) would be used and paid for every year over the entire lifetime of the dam, after accounting 
for water losses between the dam and the farm. It can be challenging for farms to sustain the 
high levels of revenue over such long periods (100 years) to justify the costs of building expensive 
dams. For these base analyses, the water supply is assumed to be 100% reliable; risk adjustment 
multipliers to account for reliability of supply are provided in Section 6.3.5. 








For example, in the Southern Gulf catchments some of the most cost-effective dam opportunities 
would cost approximately $5000 per ML per year of supply capacity at the dam wall, including the 
cost of the required supporting off-farm water infrastructure (Table 6-2). This would require farms 
to pay $537 per ML extracted to fully cover the costs of the public investment (at the base 7% 
target IRR for public investments, Table 6-6). Comparing this figure with what irrigators can afford 
to pay (Table 6-4) shows that it is unlikely any farming options could cover the costs of a dam in 
the Southern Gulf catchments at the GMs farms are likely to be able to achieve (Table 6-3, Chapter 
4). When a scheme is not viable (BCR < 1), the water cost and pricing tables can be used to 
generate approximate estimations of the BCR and the likely proportion of public development 
costs that farms would be able to cover. For example, a Broadacre farm that uses 8 ML/ha 
(measured at delivery to the farm) and has a GM of $4000 per ha per year could afford to pay 
$135/ML extracted (Table 6-4), which would cover 25% ($135/$537) of the $537/ML price 
(Table 6-6) required to cover the full costs of the public development. The BCR would, therefore, 
be 0.25 (the ratio of the amount the net farm benefits can cover to the full costs of the scheme). 
As for the example in Table 6-5, the proportion of the capital costs of infrastructure projects they 
would realistically expect to recover from users would be a decision for the public investor. 
Table 6-6 Water pricing required in order to cover costs of off-farm irrigation scheme development (dam, water 
distribution, and supporting infrastructure) at the investors target internal rate of return (IRR) 
Assumes the conveyance efficiency from dam to farm is 70% and that supply is 100% reliable. Risk adjustment 
multipliers for water supply reliability are provided in Table 6-9. Pumping costs between the dam and the farm would 
need to be added (e.g. ~$30/ML extra to lift water ~15 m from the weir pool to distribution channels). ‘$ CapEx per 
ML/y at dam’ is the capital expenditure on developing the dam and supporting off-farm infrastructure per ML per 
year of the dam’s supply capacity measured at the dam wall. Blue-shaded cells indicate $/ML cost of water. Blue-
shaded column headers are indicative of the most cost-effective large dam options available in the Southern Gulf 
catchments (Table 6-2). 

TARGET IRR 

WATER PRICE THAT WOULD NEED TO BE CHARGED IN ORDER TO COVER OFF-FARM INFRASTRUCTURE COSTS 

(%) 

($/ML charged at farm gate) 



Capital costs of off-farm infrastructure ($ CapEx per ML/y at dam) 



3,000 

4,000 

5,000 

6,000 

8,000 

10,000 

12,000 

14,000 

16,000 

3 

162 

215 

269 

323 

431 

538 

646 

754 

861 

5 

239 

319 

399 

479 

638 

798 

958 

1117 

1277 

7 

322 

429 

537 

644 

859 

1073 

1288 

1502 

1717 

10 

448 

598 

747 

897 

1196 

1495 

1794 

2093 

2392 



6.3.4 Financial targets required in order to cover costs of on-farm dams and bores 

The second generic assessments considered the case of on-farm sources of water. Indicative 
costs for on-farm water sources, including supporting on-farm distribution infrastructure, vary 
between $4000 and $15,000 per ha of farmland. Costs depend on the type of water source, how 
favourable the local conditions are for its development, and the irrigation requirement of the 
farming system. Since the farm and water source would be developed by a single investor, the 
first analyses considered the combined cost of all farm development together (without 
separating out the water component). 
392 | Water resource assessment for the Southern Gulf catchments 










Target farm gross margins required in order to cover full costs of greenfield farm development 
with water source 
Table 6-7 shows the farm GMs that would be required in order to cover various costs of farm 
development at the investor’s target IRR. Note that private on-farm water sources are typically 
engineered to a lower standard than public water infrastructure and have lower upfront capital 
costs, higher recurrent costs (higher O&M and asset replacement rates) and lower reliability. 
Based on the indicative farm GMs provided earlier (Table 6-3) and a 10% target IRR, a Broadacre 
farm with a $4000 per ha per year GM could cover total on-farm development capital costs of 
approximately $20,000/ha. A lower-capital-cost Horticulture-L farm with a GM of $7000 per ha 
per year could afford approximately $40,000/ha of initial capital costs, and a capital-intensive 
Horticulture-H farm with a GM of $11,000 per ha per year could pay approximately $30,000/ha 
for farm development (Table 6-7). This indicates that on-farm water sources may have better 
prospects of being viable than large public dams in the Southern Gulf catchments, particularly for 
broadacre farms and horticulture with lower development costs, if good sites can be identified 
for developing sufficient on-farm water resources at a low-enough cost. 
Table 6-7 Farm gross margins (GMs) required in order to achieve target internal rates of return (IRR), given various 
capital costs of farm development (including an on-farm water source) 
Assumes 100% farm performance on all farmland in all years, once construction is complete. Risk adjustment 
multipliers are provided in Section 6.3.5. Blue-shaded cells indicate the capital costs that could be afforded by farms 
with GMs of $4000 (Broadacre), $7000 (Horticulture-L) and $11,000 (Horticulture-H) per ha per year. 

TARGET IRR 

FARM GROSS MARGIN REQUIRED IN ORDER TO ACHIEVE THE FARMER'S TARGET IRR 

(%) 

($/ha/y) 



Total capital costs of farm development, including water source ($ CapEx/ha) 



10,000 

15,000 

20,000 

30,000 

40,000 

50,000 

70,000 

100,000 



Broadacre ($600/ha/y fixed costs, 70% on-farm efficiency) 

5 

1,516 

1,957 

2,398 

3,279 

4,160 

5,042 

6,804 

9,449 

7 

1,669 

2,181 

2,694 

3,718 

4,742 

5,767 

7,815 

10,888 

10 

1,923 

2,554 

3,185 

4,447 

5,709 

6,972 

9,496 

13,282 

12 

2,105 

2,821 

3,537 

4,968 

6,400 

7,832 

10,696 

14,991 

15 

2,389 

3,238 

4,087 

5,785 

7,483 

9,181 

12,578 

17,672 

20 

2,882 

3,963 

5,044 

7,206 

9,368 

11,530 

15,854 

22,340 



Horticulture-L ($1,500/ha/y fixed costs, 90% on-farm efficiency) 

5 

2,469 

2,909 

3,350 

4,231 

5,113 

5,994 

7,757 

10,401 

7 

2,637 

3,149 

3,661 

4,685 

5,710 

6,734 

8,783 

11,856 

10 

2,915 

3,546 

4,177 

5,439 

6,702 

7,964 

10,488 

14,274 

12 

3,114 

3,830 

4,546 

5,978 

7,409 

8,841 

11,705 

16,001 

15 

3,424 

4,273 

5,122 

6,820 

8,519 

10,217 

13,613 

18,708 

20 

3,962 

5,043 

6,124 

8,286 

10,448 

12,610 

16,934 

23,420 








TARGET IRR 

FARM GROSS MARGIN REQUIRED IN ORDER TO ACHIEVE THE FARMER'S TARGET IRR 

(%) 

($/ha/y) 



Total capital costs of farm development, including water source ($ CapEx/ha) 



10,000 

15,000 

20,000 

30,000 

40,000 

50,000 

70,000 

100,000 

5 

7,760 

8,201 

8,642 

9,523 

10,404 

11,286 

13,048 

15,692 

7 

8,012 

8,524 

9,036 

10,060 

11,085 

12,109 

14,158 

17,231 

10 

8,427 

9,058 

9,689 

10,951 

12,213 

13,475 

15,999 

19,785 

12 

8,720 

9,436 

10,152 

11,584 

13,016 

14,448 

17,312 

21,607 

15 

9,177 

10,026 

10,875 

12,573 

14,271 

15,970 

19,366 

24,461 

20 

9,963 

11,044 

12,125 

14,287 

16,449 

18,611 

22,935 

29,421 



Volumetric water cost equivalent for on-farm water source 

Table 6-8 converts the capital cost of developing an on-farm water source (per ML of annual 
supply capacity) into an equivalent cost for each individual ML of water supplied by the water 
source. The table can be used to estimate how much a farm could spend on developing the 
required water resources by comparing the costs per ML with what farms can afford to pay for 
water (Table 6-4). For example, a Broadacre farm with a GM of $4000 per ha per year, an annual 
farm water use of 8 ML/ha, and a target 10% IRR could afford to pay $135/ML for its water supply 
(Table 6-4), which would allow capital costs of approximately $1000 for each ML/year supply 
capacity for developing an on-farm supply (Table 6-8). Approximate indicative costs for developing 
on-farm water sources range from $500/ML to $2000/ML (based on the range of per hectare costs 
above). This alternative approach confirms that there are likely to be viable farming opportunities 
using on-farm water development in the Southern Gulf catchments. 

Table 6-8 Equivalent costs of water per ML for on-farm water sources with various capital costs of development, at 
the internal rate of return (IRR) targeted by the investor 

Assumes the water supply is 100% reliable. Risk adjustment multipliers for water supply reliability are provided in 
Table 6-9. Pumping costs to the field surface would be extra (e.g. ~$2 per ML per m dynamic head for bore pumping). 
Blue-shaded cells indicate $/ML cost of water. 

TARGET IRR 

WATER VOLUMETRIC COST-EQUIVALENT UNIT FOR VARIOUS CAPITAL COSTS OF WATER SOURCE 

(%) 

($/ML) 



Capital costs for on-farm water infrastructure ($ CapEx per ML/y at farmland surface) 



300 

400 

500 

700 

1000 

1250 

1500 

1750 

2000 

3 

22 

29 

37 

51 

74 

92 

110 

129 

147 

5 

26 

35 

44 

61 

87 

109 

131 

153 

175 

7 

31 

41 

51 

72 

102 

128 

154 

179 

205 

10 

38 

51 

63 

89 

127 

159 

190 

222 

254 

12 

43 

58 

72 

101 

144 

180 

216 

252 

288 

15 

51 

68 

85 

120 

171 

213 

256 

299 

342 

20 

65 

87 

109 

152 

217 

271 

326 

380 

434 






6.3.5 Risks associated with variability in farm performance 

This section assessed the impacts of two types of risks on scheme financial performance: those 
that reduce farm performance through the early establishment and learning years, and those 
occurring periodically throughout the life of the development. The effect of these risks is to reduce 
the expected revenue and expected GMs. 

Setbacks that occur soon after a scheme is established were found to have the largest effect on 
scheme viability, particularly at higher target IRRs. There is a strong incentive to start any new 
irrigation development with well-established crops and technologies, and to be thoroughly 
prepared for the those agronomic risks of establishing new farmland that can be anticipated. The 
analyses showed that delaying full development for longer periods than the learning time had only 
a slight negative effect on IRRs, whereas proceeding to full development before learning was 
complete had a much larger impact. This implies that it is prudent to err on the side of delaying full 
development (particularly given that, in practice, it is only possible to know when full performance 
has been achieved in retrospect). An added benefit of staging is the limiting of losses when small-
scale testing proves initial assumptions of benefits to be overoptimistic and indicates that full-
scale development could never be profitable (even after attempts to overcome unanticipated 
challenges). 

For an investment to be viable, farm GMs must be sustained at high levels over long periods. Thus, 
variability in farm performance poses risks that must be considered and managed. GMs can vary 
between years because of either short-term initial underperformance or periodic shocks. Initial 
underperformance is likely to be associated with learning, as farming practices need to be adapted 
to local conditions and to overcome initial challenges in order to reach their long-term potential. 
In addition, unavoidable periodic risks are associated with water reliability, climate variability, 
flooding, outbreaks of pests and diseases, periodic technical or equipment failures, and 
fluctuations in commodity prices and market access. Unreliability of water supply, is less easy to 
avoid than other periodic risks. Risks that cannot be avoided must be managed, mitigated where 
possible, and accounted for in determining the realistic returns that can be expected from an 
irrigation development. Such accounting would include having adequate capital buffers for 
survival through challenging periods. Another perceived risk for investors is the potential of future 
policy changes and delays in regulatory approvals. Reducing this, or any other sources of risk, in 
the Southern Gulf catchments would help make marginal investment opportunities more 
attractive. 

The results of the analyses of both periodic and learning risks are shown below. Right to farm and 
other sovereignty risks, especially with regard to access to water, may become key factors in 
future years, based on experience from elsewhere, but these are not the subject of the risk 
discussion presented here. 

Throughout this section, farm performance in a given year is quantified as the proportion of the 
long-term mean GM a farm attains: 100% performance is when this level is reached, and 0% 
equates to a performance where revenues only balance variable costs (GM = zero). 


Risks from periodic underperformance 

The analyses considered periodic risks generically, without assuming any of the particular causes 
listed above. To quantify their effects on scheme financial performance, the periodic risks were 
characterised by three components: 

• reliability – the proportion of ‘good’ years, in which ‘full’ 100% farm performance was achieved, 
with the remainder of years being termed ‘failed’ years, in which some negative impact was 
experienced 
• severity – the farm performance in a ‘failed’ year, in which some type of setback occurred 
• timing – in ‘early’ timing (in relation to a 10-year cycle), the ‘failed’ years came early in each 10-
year cycle (e.g. 80% reliability meant that ‘failed’ years occurred in the first 2 years of the 
scheme and in the first 2 years of each 10-year cycle after that). In ‘late’ timing, the ‘failed’ years 
came at the end of each 10-year cycle. In ‘random’ timing, each year was allocated the long-
term mean farm performance of ‘good’ and ‘failed’ years (frequency weighted). 


Table 6-9 summarises the effects of a range of reliabilities and severities for periodic risks on 
scheme viability. Periodic risks had a consistent proportional effect on target GMs, irrespective of 
development options or costs, so the results were simplified as a set of risk adjustment multipliers. 
The multipliers can, therefore, be applied to the target farm GMs in Section 6.3.2 (the GMs 
required in order to cover the capital costs of development at the investor’s target IRRs at 100% 
farm performance) to account for the effects of various risks. These same adjustment factors 
could be applied to the water prices that irrigators can afford to pay (Table 6-4), but would be 
used as divisors to reduce the price that irrigators could pay for water. 

Table 6-9 Risk adjustment factors for target farm gross margins (GMs), accounting for the effects of the reliability 
and severity (level of farm performance in ‘failed’ years) of the periodic risk of water reliability 

Results are not affected by discount rates. ‘Good’ years = 100% farm performance; ‘failed’ years = <100% 
performance. ‘Failed year performance’ is the mean farm GM for years in which some type of setback is experienced, 
relative to the mean GM when the farm is running at ‘full’ performance. 

FAILED YEAR 
PERFORMANCE (%) 

RISK ADJUSTMENT MULTIPLIER FOR TARGET FARM GROSS MARGINS 
(VS BASE 100% RELIABILITY TABLES) (unitless ratio) 

 

Reliability (proportion of ‘good’ years) 

 

1.00 

0.90 

0.85 

0.80 

0.70 

0.60 

0.50 

0.40 

0.30 

0.20 

85 

1.00 

1.02 

1.02 

1.03 

1.05 

1.06 

1.08 

1.10 

1.12 

1.14 

75 

1.00 

1.03 

1.04 

1.05 

1.08 

1.11 

1.14 

1.18 

1.21 

1.25 

50 

1.00 

1.05 

1.08 

1.11 

1.18 

1.25 

1.33 

1.43 

1.54 

1.67 

25 

1.00 

1.08 

1.13 

1.18 

1.29 

1.43 

1.60 

1.82 

2.11 

2.50 

0 

1.00 

1.11 

1.18 

1.25 

1.43 

1.67 

2.00 

2.50 

3.33 

5.00 



 
As expected, the greater the frequency and severity of ‘failed’ years, the greater the impact on the 
scheme viability and the greater the increase in farm GMs required in order to offset these 
impacts. As an example, the reliability of water supply is one of the more important sources of 
unavoidable variability in the productivity of irrigated farms. Water reliability (proportion of ‘good’ 
years, in which the full supply of water is available) is shown as ‘reliability’ in Table 6-9, and the 
mean percentage of water available in a ‘failed’ year (in which less than the full supply of water is 


available) is shown as the ‘failed year performance’ in 

For crops for which the quality of the produce is more important than the quantity, such as 
horticulture, the approach of reducing the planted land area in proportion to the available water 
in ‘failed’ years would be reasonable. For perennial horticulture or tree crops, it may be difficult to 
reduce (or increase) areas on an annual basis. Farmers of these crops would, therefore, tend to 
opt for systems with a high degree of reliability of water supply (e.g. 95%). For many broadacre 
crops, deficit irrigation could partially mitigate impacts on farm performance in years with reduced 
water availability, as could carryover effects from inputs (such as fertiliser) in a ‘failed’ year that 
reduce input costs the following year (see Section 4.3.4). 

Table 6-10 shows how the timing of periodic impacts affects scheme viability, providing risk 
adjustment factors for a range of reliabilities for an impact that had 50% severity with late timing, 
early timing and random (long-term frequency, weighted mean performance) timing. 

These results indicate that any negative disturbances that reduce farm performance will have a 
larger effect if they occur soon after the scheme is established, and that this effect is greater at 
higher target IRRs. For example, at a 7% target IRR and 70% reliability with ‘late’ timing (in which 
setbacks occur in the last 3 of every 10 years), the GM multiplier is 1.13, meaning the annual farm 
GM would need to be 13% higher than if farm performance were 100% reliable. In contrast, for 
the same settings with ‘early’ timing, the GM multiplier is 1.23, meaning the farm GM would need 
to be 23% higher than if farm performance were 100% reliable. The impacts of early setbacks are 
more severe than the impacts of late setbacks. 

Table 6-10 Risk adjustment factors for target farm gross margins (GMs) accounting for the effects of reliability and 
the timing of periodic risks 

Assumes 50% farm performance during ‘failed’ years, in which 50% farm performance means 50% of the GM at ‘full’ 
potential production. IRR = internal rate of return. 

TARGET 
IRR (%) 

TIMING OF FAILED 
YEARS 

RISK ADJUSTMENT MULTIPLIER FOR TARGET FARM GROSS MARGINS 
(VS BASE 100% RELIABILITY TABLES) (unitless ratio) 

 

 

Reliability (proportion of ‘good’ years) 

 

 

1.00 

0.90 

0.80 

0.70 

0.60 

0.50 

0.40 

0.30 

0.20 

3 

Late 

1.00 

1.05 

1.10 

1.16 

1.22 

1.30 

1.39 

1.50 

1.63 

Random – no bias 

1.00 

1.05 

1.11 

1.18 

1.25 

1.33 

1.43 

1.54 

1.67 

Early 

1.00 

1.06 

1.13 

1.20 

1.28 

1.37 

1.47 

1.58 

1.70 

7 

Late 

1.00 

1.04 

1.08 

1.13 

1.19 

1.26 

1.35 

1.46 

1.59 

Random – no bias 

1.00 

1.05 

1.11 

1.18 

1.25 

1.33 

1.43 

1.54 

1.67 

Early 

1.00 

1.07 

1.15 

1.23 

1.32 

1.41 

1.51 

1.62 

1.74 

10 

Late 

1.00 

1.03 

1.07 

1.12 

1.17 

1.24 

1.32 

1.42 

1.56 

Random – no bias 

1.00 

1.05 

1.11 

1.18 

1.25 

1.33 

1.43 

1.54 

1.67 

Early 

1.00 

1.08 

1.16 

1.25 

1.35 

1.45 

1.55 

1.66 

1.77 




Risks from initial ‘learning’ period 

Another form of risk arises from the initial challenges of establishing new agricultural industries in 
the Southern Gulf catchments; it includes setbacks from delays, such as gaining regulatory 
approvals, and adapting farming practices to conditions in the Southern Gulf catchments. Some of 
these risks are avoidable, provided investors and farmers learn from past experiences of 
development in northern Australia (e.g. Ash et al., 2014), avoid previous mistakes and select 
farming options that are already well proven in analogous northern Australian locations. However, 
even well-prepared developers are likely to face initial challenges in adapting to the unique 
circumstances of a new location. Newly developed farmland can take some time to reach its 
productive potential, when soil nutrient pools have been established, soil limitations ameliorated, 
suckers and weeds controlled, and pest and weed management systems established. 

‘Learning’ (used here to broadly represent all aspects of overcoming initial sources of farm 
underperformance) was assessed in terms of two simplified generic characteristics: 

•initial level of performance – the proportion of the long-term mean GM that the farm achievesin its first year
•time to learn – the number of years taken to reach the long-term mean farm performance.








Performance was represented as increasing linearly over the learning period from the starting 
level to the long-term mean performance level (100%). 
The effect of learning on scheme financial viability was considered for a range of initial levels of 
farm performance and learning times. As described above, learning had consistent proportional 
effects on target GMs, so the results were simplified as a set of risk adjustment factors (Table 
6-11). As expected, the impacts on scheme viability are greater the lower the starting level of 
farm performance and the longer it takes to reach the long-term performance level. Since these 
impacts, by their nature, are weighted to the early years of a new development, they have more 
impact at higher target IRRs. To minimise the risks of learning impacts, there is a strong incentive 
to start any new irrigation development with well-established crops and technologies, and to be 
thoroughly prepared for those agronomic risks of establishing new farmland that can be 
anticipated. Higher-risk options (e.g. novel crops, equipment or practices that are not currently in 
profitable commercial use in analogous environments) could be tested and refined on a small 
scale until locally proven. 
Table 6-11 Risk adjustment factors for target farm gross margins (GMs), accounting for the effects of learning risks 
Learning risks were expressed as the level of initial farm underperformance and the time taken to reach full 
performance levels. Initial farm performance is the initial GM as a percentage of the GM at ‘full’ performance. 
IRR = internal rate of return. 

TARGET IRR 
(%) 

INITIAL FARM 
PERFORMANCE (%) 

RISK ADJUSTMENT MULTIPLIER FOR TARGET FARM GROSS MARGINS 
(VS BASE 100% RELIABILITY TABLES) (unitless ratio) 





Learning time (years to 100% performance) 





2 

4 

6 

8 

10 

15 

3 

85 

1.01 

1.02 

1.03 

1.03 

1.04 

1.05 

75 

1.02 

1.03 

1.04 

1.05 

1.07 

1.10 

50 

1.04 

1.06 

1.09 

1.12 

1.14 

1.21 

25 

1.06 

1.10 

1.14 

1.19 

1.23 

1.35 




TARGET IRR 

INITIAL FARM 
PERFORMANCE (%) 

RISK ADJUSTMENT MULTIPLIER FOR TARGET FARM GROSS MARGINS 
(VS BASE 100% RELIABILITY TABLES) (unitless ratio) 















7 

85 

1.02 

1.03 

1.04 

1.05 

1.05 

1.07 

75 

1.03 

1.05 

1.06 

1.08 

1.09 

1.13 

50 

1.06 

1.10 

1.13 

1.17 

1.21 

1.29 

25 

1.09 

1.15 

1.22 

1.28 

1.35 

1.51 

0 

1.12 

1.21 

1.31 

1.41 

1.52 

1.83 

10 

85 

1.02 

1.03 

1.05 

1.06 

1.07 

1.09 

75 

1.04 

1.06 

1.08 

1.10 

1.11 

1.15 

50 

1.08 

1.12 

1.17 

1.21 

1.26 

1.35 

25 

1.12 

1.20 

1.28 

1.36 

1.44 

1.65 

0 

1.16 

1.28 

1.41 

1.55 

1.69 

2.10 



As indicated in the examples above, the influence of each risk individually can be quite modest. 
However, the combined influence of all foreseeable risks must be accounted for in planning, and 
the cumulative effect of these risks can be substantial. For example, the last question in Table 6-1 
shows that the combined effect of just two risks requires farm GMs to be approximately 50% 
higher than they would be without the risks. See Stokes and Jarvis (2021) for the effects of a 
common suite of risks on the financial performance of a Bradfield-style irrigation scheme. 

6.4 Cost–benefit considerations for water infrastructure viability 

6.4.1 Lessons from recent Australian dams 

CBA is widely used to help decision makers evaluate the net benefits likely to arise from 
implementing a proposed project, particularly for investments in large-scale public infrastructure. 
Despite this wide usage of CBAs, there are a few examples for which the estimated costs and 
benefits used to justify the project have been revisited at a later date. Such ex-post evaluations 
allow the outcomes of completed projects to improve planning, management and risk mitigation 
in future projects (Infrastructure Australia, 2021a). 

The few examples in which water infrastructure CBAs have been evaluated have focused on 
exploring the accuracy of the forecast capital costs. An international study of large water 
infrastructure projects showed that actual construction costs exceeded contracted costs by a 
mean of 96% (Ansar et al., 2014). Similarly, an Australian-focused study found mean cost overruns 
of 120% (Petheram and McMahon, 2019). There is evidence of a systematic tendency across a 
range of large infrastructure projects for proponents to substantially under estimate development 
costs (Ansar et al., 2014; Flyvbjerg et al., 2002; Odeck and Skjeseth, 1995; Wachs, 1990; Western 
Australian Auditor General, 2016). 

Ex-post evaluations of project benefits are even scarcer. One international study found that large 
dam developments frequently underperformed, whereby ‘irrigation services have typically fallen 
short of physical targets, did not recover their costs and have been less profitable in economic 


terms than expected’ (World Commission on Dams, 2000). In particular, this study highlighted 
inaccurate and overestimated forecasting of future irrigation demand for water from dam 
developments. 

Review of recent Australian dams 

The Roper River Water Resource Assessment technical report on agricultural viability and socio-
economics (Stokes et al., 2023) conducted a systematic review of the five most recently built dams 
in Australia (Figure 6-2, Table 6-12) to address the gap in the ex-post evaluations. The goal was to 
assess how well Australian dam projects have achieved their anticipated benefits and to make the 
learnings available for future planning. These lessons provide a context for interpreting CBAs from 
project proponents and independent analysts, and the financial analyses provided in the previous 
section. The key lessons from that review are summarised below, and the full details are reported 
in Webster et al. (2024). 

 

Locations of five dams used in costing review map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\5_Agriculture_economics\2_Victoria\1_GIS\1_Map_docs\Se-V-503_Map_Australia_and_river_basins_new dams_V1.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 6-2 Locations of the five dams used in this review 

The dams are numbered in blue as 1: New Harvey Dam, 2: Paradise Dam, 3: Meander Dam, 4: Wyaralong Dam and 
5: Enlarged Cotter Dam. 

 


Table 6-12 Summary characteristics of the five dams used in this review 

The documents reviewed for each dam are cited in the companion technical report on agricultural viability and socio-
economics (Webster et al., 2024). CBA = cost–benefit analysis. 

 

NEW HARVEY DAM 

PARADISE DAM 

MEANDER DAM 

WYARALONG DAM 

ENLARGED COTTER DAM 

State/territory 

WA 

Qld 

Tas 

Qld 

ACT 

Date completed 

2002 

2005 

2008 

2011 

2012 

Capacity (GL) 

59 

300 

43 

103 

78 

New dam or 
redevelopment of 
existing dam? 

Replaces Harvey 
weir (built 1916, 
extended 1931), 
capacity of ~10 GL 

New 

New 

New 

Replaces original 
Cotter Dam (built 
1915, extended 1951), 
capacity of ~4 GL 

Primary use(s) 
proposed for 
water from dam 

Irrigated 
agriculture 

Irrigated 
agriculture, 
water supply 

Irrigated 
agriculture, 
environmental 
flows, hydro-
electric power 

Water supply to 
South East 
Queensland 

Water supply for 
Canberra 

Type of key 
project 
documents used 
for this review 

Proposed water 
allocation plans 
(no CBA available) 

CBA and 
economic 
impact 
assessment 

CBA 

Environmental 
Impact Statement 
(EIS) 

(no CBA available) 

EIS (which included 
CBA information, but 
the actual CBA report 
was unavailable) 



Summary of key issues identified 

This review highlighted a number of issues with the historical use of CBAs for recently built dams 
in Australia and suggested how CBAs could be more rigorously addressed (Table 6-13). These 
issues arise because of the complexity of the forecasts and estimates required in planning large 
infrastructure projects and because of pressures on proponents that can introduce systematic 
biases. However, this report acknowledges that flaws with the use of CBAs in large public 
infrastructure investment decisions are not unique to regional Australia or to water infrastructure 
– they are systemic and occur in relation to many different types of infrastructure globally. Under 
such circumstances, it would be inequitable to apply more rigour to CBAs only for some select 
investments, geographic regions, and infrastructure classes before the same standards are 
routinely applied in all cases. And there is no incentive for individual proponents to apply more 
rigour to CBAs if their proposals would suffer from unfavourable comparisons with alternative or 
competing investments with exaggerated cost-to-benefit ratios (CBRs). 

In the short term, the main value of the information provided here is to enable more critical 
interpretation and evaluation of CBAs so that more-informed decisions can be made about the 
likely viability (and relative ranking) of projects in practice. In particular, it highlights several 
aspects of CBAs regarding which the claims of proponents warrant critical scrutiny. The longer 
term value of this analysis is that it has identified many issues similar to those raised in past review 
cycles of Infrastructure Australia’s CBA best-practice guidelines and in the recommendations that 
are being progressively added to those guidelines to improve how large public investments are 
evaluated (Infrastructure Australia, 2021a, 2021b). 


Table 6-13 Summary of key issues and potential improvements arising from a review of recent dam developments 

 

KEY ISSUE 

POTENTIAL IMPROVEMENTS 

1 

There is a lack of clear documentary evidence regarding 
the actual outcome of dam developments compared 
with the assumptions made in ex-ante proposals, 
Environmental Impact Statements (EISs) and cost–
benefit analyses (CBAs). Ex-post evaluations or post-
completion reviews have either not been prepared or 
not been made publicly available. 

Conducting ex-post evaluations of developments and making 
these publicly available (as recommended by 2021 guidance from 
Infrastructure Australia (Infrastructure Australia, 2021a, 2021b) 
and in the 2022 National Water Grid Investment Framework 
(NWGA 2022)) would enable lessons learned to be shared and 
benefit future developments. 

2 

Predicted increases in water demand from specific 
developments generally do not appear to arise at the 
scale and/or within the time frame forecast. While the 
reasons for this are varied and context-dependent, there 
does appear to be a systematic bias towards 
overestimation of the magnitude and rate at which new 
benefits would flow. 

Recognising the tendency towards a systematic bias of 
overstating benefits and understating costs, CBAs in project 
proposals could be improved by: (i) further efforts to present 
unbiased financial analysis (e.g. independent review) and ensuring 
appropriate sensitivity analysis is included in all proposals, (ii) 
developing broadly applicable and realistically achievable 
benchmarks for evaluating proponents’ assumptions and financial 
performance claims, (iii) using past experiences and lessons 
learned from previous projects with a similar context to inform the 
analysis presented in the proposals (building on Issue 1 above), and 
(iv) presenting a like-for-like comparison of cost-to-benefit ratios 
(CBRs) for the proposed case vs standard alternatives (such as 
water buybacks or a smaller dam, possibly better matched to 
realistic future demand). 

3 

The systematic bias towards optimism in proposals is 
exacerbated by mismatches between forecast demand 
and the full supporting infrastructure required to 
enable this demand to be realised, resulting in additional 
capital investment (pipelines, treatment plants, etc.) 
being required that was not costed in the original 
proposal. 

The same improvements as for Issue 2 in recognising and 
addressing inherent bias apply here. 

4 

Developments are justified based on a complex mix of 
multiple market and non-market benefits, many of 
which are hard to monetise and capture in a single net 
present value (NPV) figure. 

CBAs could be improved by presenting clear information on the full 
portfolio of benefits (and costs and disbenefits) anticipated to arise 
from a project. While the quantitative part of the CBA would 
analyse the easily monetised costs and benefits (with metrics such 
as CBR and NPV), benefits that are hard to monetise could also be 
formally presented in whatever form is most appropriate to the 
magnitude and nature of the particular benefit. This presentation 
would enable the relative importance of each element of the mix 
to be weighed and given appropriate consideration, rather than 
attention being focused on a single NPV figure, which may have 
omitted key elements of the project. 

5 

Improved water security and reliability of supply is 
often the most important benefit offered by dam 
developments, while also being the hardest to monetise. 
Dams provide a form of insurance against the risk that 
water may not be available when needed in the future. 
Assessing the value of this insurance requires 
consideration of the cost of lack of water supply when 
needed and the likelihood that this could occur. 

CBAs could be improved by providing clear information on exactly 
how the development will serve to improve water security, the 
likelihood that such insurance will be required (i.e. an estimate of 
the risk), and the estimated social and economic impacts if the 
insurance was not there when required. Such information could be 
presented alongside, and given equal prominence with, other 
information regarding the proposal, including the estimated NPV. 
This is preferable to attempting to ‘force’ the benefit into an NPV 
calculation that is ill-equipped to deal with such a benefit. 



6.4.2 Demand trajectories for water use 

For irrigated agriculture to expand in the Southern Gulf catchments, additional water will be 
required. Forecasting that growth in demand is essential, both for planning new water 
infrastructure and for evaluating individual water infrastructure proposals. This will ensure 
assumed demand trajectories for water, and the associated value that can be generated from 
irrigated agriculture to justify the costs of that infrastructure, are reasonable. Australian Bureau of 


Statistics data series on historical agricultural production and water use were analysed to derive 
trends and relationships for benchmarking realistic growth trajectories in Queensland (

(a) Australia 

 

(b) Queensland 

 



Trend in gross value of ag production, Aust
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010,00020,00030,0001981-901991-002001-102011-21GVAP ($M)
DecadeCrops (horticulture)Crop (other)Livestock
Trend in gross value of ag production, Qld
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020004000600080001981-901991-002001-102011-21GVAP ($M)
DecadeCrops (horticulture)Crop (other)Livestock
Figure 6-3 Trends in gross value of agricultural production (GVAP) in (a) Australia and (b) Queensland over 40 years 
(1981–2021) 

Data points are decade averages of annual values. The ‘Crop (other)’ category is predominantly broadacre farming. 

Source: (ABS, 2022) 

Horticultural produce is typically perishable and expensive to store and transport, and must meet 
stringent phytosanitary (plant health) standards for export, so most Australian horticultural 
produce (~70%) is sold domestically for consumption shortly after harvest. Growth in horticultural 
industries is, therefore, constrained by growth in demand from local consumers. The current rate 
of growth in the value of Australian horticulture is $2.7 billion per decade (step changes in gross 
value of agricultural production (GVAP) from 1981–90 to 2011–21 are shown in Figure 6-3). Any 
new irrigated development would compete for some share of that growth, providing a benchmark 
guide for the scale of new horticulture that could realistically be included in any new irrigation 
scheme. It also provides a benchmark for the trajectory at which high-value horticulture (and the 
associated demand for high-priority water) could grow towards the ultimate scheme potential. 

In addition, the scale of new horticultural expansion for any single crop is limited by seasonal gaps 
in supply, so the horticulture in any single location is typically a mix of products that fill the niche 
market gaps that the location can supply (usually dictated by climate, but sometimes a result of 
other factors, such as backloading opportunities; see Chapter 4), rather than being a monoculture 
of the most valuable crop alone. Data on how the value of irrigated agriculture has increased with 
increasing irrigation water availability over time provide an indicative benchmark of how much 
gross value such a mix of new agricultural activities could generate for each new GL of irrigation 
water that becomes available (Figure 6-4). Based on the trendlines in Figure 6-4, each extra new 
GL of water use could produce: 

• between $2.1 and $3.7 million of gross value from mixed fruit industries 
• between $5.6 and $10.3 million of gross value from mixed vegetable industries 
• between $2.5 and $5.0 million of gross value from mixed horticulture (combined), or 
• between $0.8 and $1.7 million of gross value from a typical mix of agriculture overall. 


Growth trends in the value of broadacre crops are stronger than those for horticulture (Figure 6-
3); they are a combination of increases in both product volumes and the value per unit product. 
Unlike horticultural crops, bulk broadacre commodities are stored and traded on large global 


markets (with multiple competing international buyers), which could easily absorb the scale of 
increases in production that would be possible from the Southern Gulf catchments. However, 
supply chains, rather than markets, pose a challenge for new broadacre production. Despite 
northern Australia being geographically closer than southern Australia to many key markets, the 
supply chains for northern Australian produce are longer, because most agricultural exports leave 
through southern ports. For example, the Port of Townsville currently does not handle bulk food-
grade containers (for either import or export). The challenge is to develop transport and handling 
capacity for exports and balance that with compatible imports to avoid the added cost of dead 
freighting empty containers (CRCNA, 2020). 

(a) Fruits 

 

(c) Fruits and vegetables combined 

 

(b) Vegetables 

 

(d) Total agriculture 

 



Trend in gross value of irrigated ag with water applied, fruit
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Trend in gross value of irrigated ag with water applied, fruit and vegetable
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Trend in gross value of irrigated ag with water applied, vegetable
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Trend in gross value of irrigated ag with water applied, total agriculture
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Figure 6-4 National trends for increasing gross value of irrigated agricultural production (GVIAP) as available water 
supplies have increased for (a) fruits, (b) vegetables, (c) fruits and vegetables combined, and (d) total agriculture 

Source: (ABS, 2022) 

6.4.3 Costs of enabling infrastructure 

A range of infrastructure would be required to support the development of a new irrigation 
scheme in the Southern Gulf catchments, both within the scheme itself and beyond. Any 
infrastructure that is not included in the initial water development contract but is required to 
enable the new water resources to be used effectively (and to achieve their anticipated benefits) 
will require construction after the contracted project is complete, often at public expense. The 
types of infrastructure addressed here are those that would not typically be included in a formal 
CBA or be built by the water infrastructure developer or farmers. Within the context of a large 
irrigation development, such enabling infrastructure can be considered ‘hard’ or ‘soft’, which can 
be broadly defined as follows: 


• Hard infrastructure refers to the physical assets necessary for a development to function. It can 
include water storage, roads, irrigation supply channels, energy, and processing infrastructure, 
such as sugar mills, cotton gins, abattoirs and feedlots. 
• Soft infrastructure refers to the specialised services required for maintaining the economic, 
health, cultural and social standards of a population. These are indirect costs of a development 
and are usually less obvious than hard infrastructure costs. They can include expenses that 
continue after the construction of a development has been completed. Soft infrastructure can 
include: 
– physical assets, such as community infrastructure (e.g. schools, hospitals, housing) 
– non-physical assets, such as institutions, supporting rules and regulations, compensation 
packages, and law enforcement and emergency services. 





New processing infrastructure and community infrastructure are particularly pertinent to large, 
remote, greenfield developments, and these costs to other providers of infrastructure can be 
substantial, even after a new irrigation scheme has been developed. For example, a review of the 
Ord-East Kimberley Development Plan (for expansion of the Ord irrigation system by ~15,000 ha) 
found additional costs of $114 million to the WA Government beyond the planned $220 million 
state investment in infrastructure already provided to directly support the expansion (Western 
Australian Auditor General, 2016). 

This section provides an indication of the additional public and private infrastructure required to 
support a new irrigation development (once the main water infrastructure and farms are built) 
and the costs of the additional investments required. The intention is to highlight potentially 
overlooked costs of infrastructure that is required to realise the benefits of development and 
population growth in a region, rather than to diminish the potential benefits. 

Costs of hard infrastructure 

Establishing new irrigated agriculture in the Southern Gulf catchments would involve the initial 
costs of land development, water infrastructure (which could include distribution and re-
regulation or balancing of storages), and farm set-up (for equipment and facilities on each new 
farm). It may also involve costs associated with constructing processing facilities, extending 
electricity networks, and upgrading road transport. 

The costs of water storage and conveyance are provided in Chapter 5. Indicative costs for 
processing facilities are provided in Table 6-14, and indicative costs for roads and electricity 
infrastructure are provided in Table 6-15. Indicative costs for transporting goods to key markets 
are listed in Table 6-16. All table data are summaries of information provided in the companion 
technical report on agricultural viability and socio-economics (Webster et al., 2024). 

Table 6-14 Indicative costs of agricultural processing facilities 

ITEM 

CAPITAL COST 

OPERATING COST 

COMMENT 

Meatworks 

$35 million 

$340/head 

Operational capacity 100,000 head/y 

Cotton gin 

$32 million 

$1.1 million/y plus 
$24 to $35 per 
bale 

Operational capacity of 1,500 bales/day 
Operating costs depend on the scale of the gin, and the source of 
energy 

Sugar mill 

$409 million 

$34 million/y 

Operational capacity of 1000 t cane/h, 6-month crushing season 
Basic mill producing sugar only (no electricity or ethanol) 




Table 6-15 Indicative costs of road and electricity infrastructure 

ITEM 

CAPITAL COST 

COMMENT 

Roads 

 

 

Seal dirt road 

$0.31 to $2.4 million per 
km 

Upgrade and widen dirt road to sealed road 

New bridges and 
floodway 

$27.4 million 

Costs of bridges and floodways vary widely 

Electricity 

 

New generation capacity may also be required 

Transmission lines 

$0.34 to $1.57 million 
per km 

High-voltage lines deliver bulk flow of electricity from 
generators over long distances 

Distribution lines 

$0.22 to $0.49 million 
per km 

Lower-voltage lines distribute power from substations 
over shorter distances to end users 

Substation 

$1.3 to $12.2 million 

Transformers and switchgear connect transmission and 
distribution networks 



 
Table 6-16 Indicative road transport costs between the Southern Gulf catchments and key markets and ports 

The top section of the table gives trip costs from Mount Isa to key destinations. The bottom section gives distance-
based costs of getting goods from within the catchment to Mount Isa (on unsealed roads) and approximate distance-
based costs of getting goods from Mount Isa on sealed roads to other destinations (not specifically listed). 

DESTINATION 

TRANSPORT COST 

 

Unrefrigerated 

Refrigerated 

Cattle 

 

Transport costs from Mount Isa ($/t) 

Adelaide 

404 

480 

364 

Brisbane 

295 

337 

266 

Cairns 

181 

235 

163 

Darwin 

242 

293 

218 

Fremantle 

748 

793 

673 

Karumba 

87 

103 

78 

Melbourne 

423 

467 

380 

Port Hedland 

505 

612 

455 

Sydney 

398 

426 

358 

Townsville 

143 

161 

129 

Wyndham 

285 

344 

257 

 

Transport costs by distance ($ per t per km) 

Properties to Mount Isa 

0.28 

0.32 

0.25 

Mount Isa to key markets/ports 

0.16 

0.18 

0.14 



 


Costs of soft infrastructure 

The availability of community services and facilities would play an important role in attracting 
people to (or deterring them from) living in a new development in the Southern Gulf catchments. 
If local populations increase as a result of new irrigated developments, then the demand for public 
services would increase, and provision of those services would need to be anticipated and planned 
for. Indicative costs for constructing a variety of facilities that may be required for supporting 
population growth are listed in Table 6-17. Each 1000 people in Australia require 2.3 (in ‘Major 
cities’) to 4.0 (in ‘Remote and Very remote areas’) hospital beds, served by 16 full-time equivalent 
(FTE) hospital staff, and $3.5 million/year funding to maintain current mean national levels of 
hospital service (AIHW, 2023). Health care services in remote locations generally focus on 
providing primary care and some secondary care. More specialised tertiary services tend to be 
concentrated in referral hospitals, which are generally located in big cities but also serve the 
surrounding area. Primary schools tend to be smaller and more widespread than secondary 
schools, which are larger and more centralised. 

Table 6-17 Indicative costs of community facilities 

Costs are quoted for Darwin as a reference capital city for northern Australia. Costs in remote parts of northern 
Australia, including the Southern Gulf catchments, are estimated to be approximately 30% to 60% higher than those 
quoted for Darwin. School costs were estimated separately based on a number of locations across northern Australia. 
See the companion technical report on agricultural viability and socio-economics (Webster et al., 2024) for details. 

ITEM 

CAPITAL COST 

COMMENT 

Hospital 

$0.2 to $0.5 million per 
bed 

Higher-end costs include a major operating theatre and a 
larger hospital area per bed 

School 

$27,000 to $35,000 per 
student 

Secondary schools tend to be larger and more centralised 
than primary schools 

House (each) 

$585,000 to $850,000 

Single- or double-storey house, 325 m2 

Unit (each) 

$230,000 to $395,000 

Residential unit (townhouse), 90 to 120 m2 

Offices 

$2400 to $3450 per m2 

1 to 3 storeys, outside central businesses district 



 
The demand for community services is growing, both from population increases in Australia and 
rising community expectations. New infrastructure would be built to service that demand, 
irrespective of any development in the Southern Gulf catchments. However, if new irrigation 
projects encourage people to live in the Southern Gulf catchments, this could then shift the 
locations at which some services would be delivered and the associated infrastructure built. The 
costs of delivering services and building infrastructure are generally higher in very remote 
locations like the Southern Gulf catchments. The net cost of any new infrastructure built to 
support development in the Southern Gulf catchments is the difference in the cost of shifting 
some infrastructure to this very remote location (rather than the full cost of the facilities (Table 6-
17) which would otherwise have been built elsewhere). 


6.5 Regional-scale economic impact of irrigated development 

New irrigated development in the Southern Gulf catchments could provide economic benefits to 
the region in terms of both increased economic activity and jobs. The size of the total economic 
benefit experienced would depend on the scale of the development, the type of agriculture that 
was established, and how much spending from the increased economic activities occurred within 
the region. Regional economic impacts are an important consideration for evaluating potential 
new water development projects. 

It was estimated that each million dollars spent on construction within the Southern Gulf 
catchments would generate an additional $1.06 to $1.09 million of indirect benefits ($2.06 to 
$2.18 million total regional benefits, including the direct benefit of each million dollars spent on 
construction). It was estimated that each million dollars of direct benefit from new agricultural 
activity would generate an additional $0.46 to $1.82 million in regional economic activity 
(depending on the particular agricultural industry). 

The full, catchment-wide impact of the economic stimulus provided by an irrigated agriculture or 
aquaculture development project extends far beyond the impact on those businesses and workers 
directly involved in either the short term (construction phase) or the longer term (operational 
phase). Businesses directly benefiting from the project would need to increase their purchases of 
the raw materials and intermediate products used by their growing outputs. Should any of these 
purchases be made within the surrounding region, this would provide a stimulus to those 
businesses from which they purchase, contributing to further economic growth within the region. 
Furthermore, household incomes would increase as a result of the employment of local residents 
as a consequence of the direct and/or production-induced business stimuli. As a proportion of this 
additional household income would be spent in the region, economic activity within the region 
would be further stimulated. Accordingly, the larger the initial amount of money spent within the 
region, and the larger the proportion of that money re-spent locally, the greater the overall 
benefits that would accrue to the region. 

The size of the impact on the local regional economy can be quantified by regional economic 
multipliers (derived from I–O tables that summarise expenditure flows between industry sectors 
and households within the region): a larger multiplier indicates larger regional benefits. These 
multipliers can be used to estimate the value of increased regional economic activity likely to flow 
from a stimulus to particular industries, focusing on construction in the short term and various 
types of agriculture in the longer term. 

It is also possible to estimate the increase in household incomes in the region, and then estimate 
the approximate number of jobs represented by the increased economic activity, including both 
those directly related to the increase in agriculture and those generated indirectly within other 
industries in the region. 

Not all expenditure generated by a large-scale development will occur within the local region. The 
greater the leakage (i.e. the amount of direct and indirect expenditure occurring outside the 
region), the smaller the resulting economic benefit enjoyed by the region. Conversely, the greater 
the retention of the initial expenditure and subsequent indirect expenditure within the region, the 
greater the economic benefit and the number of jobs created within the local region. However, a 
booming local economy can also bring with it a number of issues that can place upward pressure 


on prices (including materials, houses and wages) in the region, negating some of the positive 
impacts of the development. If some of the unemployed or underemployed people within the 
Southern Gulf catchments could be engaged as workers during the construction or operational 
phases of the development, this could reduce pressure on local wages and reduce the leakage 
resulting from the use of fly-in fly-out (FIFO) or drive-in drive-out (DIDO) workers, retaining more 
of the benefit from the project within the local region. However, the current low unemployment 
rate within the Southern Gulf catchments (Chapter 3) suggests there may be difficulties in sourcing 
local workers from within the region. 

The overall regional benefit created by a particular development depends on both the one-off 
benefits from the construction phase and the ongoing annual benefits from the operational phase. 
The benefits from the operational phase may take a number of years to reach the expected level, 
as new and existing agricultural enterprises learn and adapt to making full use of the new 
opportunities presented by the development. It is important to note that the results presented 
here are based on illustrative scenarios incorporating broad assumptions, are derived from an I–O 
model developed for an I–O region that is much larger than the Southern Gulf catchments study 
area, and are subject to the limitations of the method. 

6.5.1 Estimating the size of regional economic benefits 

To develop regional multipliers for the Southern Gulf catchments, it was necessary to use the 
available information and models for the Queensland section of the Southern Gulf catchments I–O 
region. The regional I–O table developed by the Office of the Government Statistician of the 
Queensland Government provided coverage for the north-west region of Queensland (Office of 
the Government Statistician, Queensland Government, 2004 (Figure 6-5)). These results can be 
considered broadly applicable to the NT component of the Assessment area, noting the caveats 
for the I–O model below. For more details, see the companion technical report on agricultural 
viability and socio-economics (Webster et al., 2024). 

Data are presented to show how the economic circumstances of the Southern Gulf catchments 
compare with those of the I–O region (Table 6-18). The I–O model covers a much wider geographic 
scale than the Southern Gulf catchments (307,082 km2 for north-west Queensland, compared with 
108,097 km2 for the Southern Gulf catchments). However, the regionally important city of Mount 
Isa falls within both regions. Both geographic scale and degree of urbanisation can affect the 
relative complexity of the economic structures in each region. 

There are wide variations in the size of the multipliers for the various industries within the 
Queensland and north-west Queensland I–O regions. Industries with larger local regional 
multipliers would be expected to benefit more from development within the I–O region. For 
example, agricultural industries generated smaller multipliers than mining and construction for 
both I–O models. However, a simple comparison of I–O multipliers can be misleading when 
considering the different benefits from regional investment, because some impacts provide a 
short-term, one-off benefit (e.g. the construction phase of a new irrigation development) while 
others provide a sustained stream of benefits over the longer term (e.g. the production phase of a 
new irrigation scheme). A rigorous comparison between specific regional investment options 
would require NPVs of the full cost and benefit streams to be calculated. 


 

Extent of regional input models map
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Figure 6-5 Queensland’s north-west region used in the input–output (I–O) analyses relative to the Southern Gulf 
catchments Assessment area 

 

Table 6-18 Key 2021 data comparing the Southern Gulf catchments with the related I–O analysis region 

 

SOUTHERN GULF CATCHMENTS† 

NORTH-WEST QUEENSLAND I–O REGION‡ 

Land area (km2) 

108,097 

307,081.5 

Population 

22,493 

30,377 

Percentage male 

51.74 

52.11 

Percentage Indigenous 

27.28 

27.03 

Median age 

31 

32 

Median household income 

$109,429 

$104,312 

Contribution of agriculture, forestry 
and fishing to employment in the 
region 

2.67% 

8.56% 

Major industries of employment – top three industries in region (by % of employment 2021) 

Largest employer in region 

Mining 

Mining 

2nd largest employer in region 

Health care and social assistance 

Health care and social assistance 

3rd largest employer in region 

Education and training 

Public administration and safety 

Gross value of total agriculture in 
region§ 

$243 million 

$945 million 



† Statistics for the Southern Gulf catchments region (ABS, 2021) have been estimated using the weighted mean of ABS 2021 census data obtained by 
SA2 statistical region, with weighting based on the proportion of relevant ABS SA2 statistical regions falling within the catchments region. 
‡ ABS 2021 census data (ABS, 2021). 
§ ABS value of agricultural commodities produced 2020–21 by region, report VACPDCASGS202021 (ABS, 2022). 
I–O = input–output. 


6.5.2 Indirect benefits during the construction phase of a development 

Initially, building new infrastructure (on-farm and off-farm development, including construction of 
related supporting infrastructure, such as roads, schools and hospitals) comes at a cost. But the 
additional expenditure within a region (which puts additional cash into people’s and businesses’ 
pockets) would increase regional economic activity. This creates a fairly short-term economic 
benefit to the region during the construction phase, provided that at least some of the 
expenditure occurs within the region and is not all lost from the region due to leakage. 

The regional impacts of the construction phase of potential developments were estimated using a 
scenario approach for the scales of development. The analyses modelled regional impacts for five 
different indicative sizes of developments in the Southern Gulf catchments. Total capital costs, 
including costs of labour and materials required by the project, ranged from $250 million to 
$4 billion. The smallest scale of development in Table 6-19, with a capital cost of $250 million, 
broadly represents approximately 20 new farm developments with their own on-farm water 
sources enabling approximately 10,000 ha of irrigation for horticulture and broadacre farming 
(based on costing information from the companion technical report on agricultural viability and 
socio-economics (Webster et al., 2024)). The second-smallest scenario, with a $500 million capital 
cost, could represent a similar development to the first but with 20,000 ha of new irrigated 
farmland; this level of investment could also include a new processing facility (such as a cotton gin) 
required by (and supported by) this scale of agricultural development. Alternatively, the 
$500 million development could represent a large off-farm water infrastructure development (e.g. 
see Table 6-2) and related farm establishment costs. The larger scales of development, at 
$1 billion or $2 billion, shown in Table 6-19, indicate outcomes from combining potential 
developments in various ways (such as one large off-farm dam and multiple on-farm water 
sources). They also include investment in indirect supporting infrastructure across the region, such 
as roads, electricity and community infrastructure (see indicative costs in Section 6.4.3). 

Table 6-19 Regional economic impact estimated by I–O analysis for the total construction phase of an irrigated 
agricultural development based on estimated Type ll multipliers determined from the north-west Queensland I–O 
models 

Estimates represent an upper bound, because some assumptions of I–O analysis are violated in the case of such a 
large public investment in a region where existing irrigated agricultural activity is so low. Leakage to other regions and 
other countries is accounted for by reducing the proportion of expenditure (and benefits) within the I–O region. 
I–O = input–output. 

DEVELOPMENT CAPITAL 
COST ($ billion) 

TOTAL REGIONAL ECONOMIC ACTIVITY WITHIN I–O REGION AS A RESULT OF THE CAPITAL COST OF THE 
DEVELOPMENT ($ billion) 

 

Southern Gulf catchments based on north-west Queensland I–O model 

 

Proportion of total scheme-scale capital cost made locally within the I–O region 

 

65% 

50% 

35% 

0.250 

0.26 

0.20 

0.14 

0.500 

0.53 

0.41 

0.28 

1.000 

1.06 

0.81 

0.57 

2.000 

2.11 

1.63 

1.14 

4.000 

4.23 

3.25 

2.28 




The proportion of expenditure during the construction phase that would be spent within the 
region depends on the types of costs, including labour, materials and equipment. It is likely that 
wages would be paid to workers sourced both from within the region and from elsewhere. The 
likely proportion of labour costs for each source of workers would depend on the availability of 
appropriately skilled labour within the region. For example, a highly populated region (more than 
100,000 people) with a high unemployment rate (more than 10%) and a skilled labour force is 
likely to be able to supply a large proportion of the workers required from within the region. 
However, a sparsely populated region like the Southern Gulf catchments is more likely to need to 
attract many workers from outside the region, either on a FIFO or DIDO basis or by encouraging 
migration to the region. Similarly, some regions may be better able to supply a large proportion of 
the required materials and equipment from within the region, whereas construction projects in 
other locations may not be able to source what they need locally and instead need to import a 
significant proportion into the region from elsewhere. The low representation of the required 
supplying industries in the Southern Gulf catchments means that most construction supplies 
would be likely to be sourced from other parts of Australia (and internationally). 

A review of five large dam projects across the country showed that the proportions of local 
construction expenditure sourced within a region (as opposed to being imported, with no impact 
on the local regional economy) varied significantly. Thus, the analyses considered three levels for 
the proportion spent locally: 65% (i.e. low leakage), and 50%, and 35% spent locally (i.e. high 
leakage). However, note that leakage might be higher (i.e. <35% spent locally) for a very remote 
region like the Southern Gulf catchments. In cases of high leakage, the knock-on benefits would 
instead occur in the regions supplying the goods and services (a large proportion of which are 
likely to be elsewhere in the state). 

Table 6-19 shows estimates of the regional economic benefit for the construction phase of a new 
development for five scales of scheme capital cost ($0.25 billion to $4 billion) and the three levels 
of leakage described above. Clearly, the proportion of scheme construction costs spent within the 
region has a significant impact on the size of the regional economic benefit experienced. If a large 
proportion of the initial expenditure in the Southern Gulf catchments leaked outside, the benefit 
of the initial construction investment would be less concentrated in the local Southern Gulf 
catchments’ economy and would spread to those locations supplying the goods and services. 

6.5.3 Indirect benefits during the operational phase of a development 

Regional impacts of irrigation development are presented for scenarios using four indicative scales 
of increase in GVAP ($25, $50, $100 and $200 million per year, indicative of potential outcomes). 
At the low end ($25 million/year), this could represent 10,000 ha of new plantation timber, while 
the high end ($200 million/year) could represent 10,000 ha of mixed broadacre cropping and 
horticulture (based on farm financial estimates for the various crops presented in Chapter 4), with 
other crop options falling in between. Estimated regional impacts are shown as the total increased 
economic activity (Table 6-20) and the associated estimated increases in incomes and employment 
(Table 6-21) for each category of agricultural activity (beef cattle, agriculture excluding beef cattle, 
and aquaculture, forestry and fishing. 

As can be seen from the economic impacts (Table 6-20), an irrigation scheme that increases the 
output of the beef cattle industry could have a larger impact on total regional economic activity 


than a scheme that promotes agriculture excluding beef cattle, while the smallest regional 
economic benefit would derive from a development focused on aquaculture, forestry and fishing. 

Table 6-20 Estimated regional economic impact per year in the Southern Gulf catchments resulting from four scales 
of direct increase in agricultural output (rows) for the different categories of agricultural activity (columns) using 
the I–O model for north-west Queensland 

Increases in agricultural output are assumed to be net of the annualised value of contributions towards the 
construction costs. Estimates are based on Type ll multipliers determined from the I–O model for each year of 
agricultural production. Estimates represent an upper bound, because some assumptions of I–O analysis are violated 
in the case of such a large public investment in a region where existing agricultural activity is so low. Leakage to other 
regions and other countries is accounted for by reducing the proportion of expenditure (and benefits) within the 
region. 

DIRECT INCREASE IN 
AGRICULTURAL OUTPUT PER 
YEAR NET OF CONTRIBUTION 
TO CONSTRUCTION COSTS 
($ million) 

TOTAL ANNUAL VALUE OF INCREASED ECONOMIC ACTIVITY IN I–O REGION 
– DIRECT, PRODUCTION-INDUCED AND CONSUMPTION-INDUCED 
($ million) 

 

Southern Gulf catchments based on north-west Queensland I–O model 

 

Type of agricultural development 

 

Beef cattle 

Agriculture excluding beef cattle 

Aquaculture, forestry and fishing 

25 

46 

38 

33 

50 

91 

76 

66 

100 

182 

152 

132 

200 

364 

303 

265 



 
The results for employment (Table 6-21) are closely related to those for impacts on regional 
economic activity, but the two measures do reveal some differences. Additional FTE jobs arising in 
the region may require additional community infrastructure (e.g. schools, health services) if 
workers move to fill these jobs from other parts of the country, resulting in population growth. 
However, additional infrastructure would not be necessary should these additional jobs be filled 
by currently unemployed or underemployed local people. Estimates of the expected increases in 
incomes were divided between Indigenous and non-Indigenous households, using methods 
outlined by Jarvis et al. (2018), with most increases expected to flow to non-Indigenous 
households (Table 6-21). 

For example, if new irrigation development in the Southern Gulf catchments directly enabled an 
extra $100 million of cropping output per year, the region could benefit from an extra $152 million 
of economic activity recurring annually (Table 6-20) and generate approximately 294 new FTE 
ongoing jobs, depending on the type of agriculture (Table 6-21). 


Table 6-21 Estimated impact on annual household incomes and full-time equivalent (FTE) jobs within the Southern 
Gulf catchments resulting from four scales of direct increase in agricultural output (rows) for the various categories 
of agricultural activity (columns) 

Increases in agricultural output are assumed to be net of the annualised value of contributions towards the 
construction costs. Estimates are based on Type ll multipliers determined from two independent I–O models for each 
year of agricultural production. Estimates represent an upper bound, because some assumptions of I–O analysis are 
violated in the case of such a large public investment in a region where existing agricultural activity is so low. Leakage 
to other regions and other countries is accounted for by reducing the proportion of expenditure (and benefits) within 
the region. 

DIRECT INCREASE IN 
AGRICULTURAL OUTPUT PER 
YEAR NET OF ANY 
CONTRIBUTION TO 
CONSTRUCTION COSTS 
($ million) 

TOTAL ANNUAL VALUE OF INCREASED ECONOMIC ACTIVITY IN I–O REGION 
– DIRECT, PRODUCTION-INDUCED AND CONSUMPTION-INDUCED 

($ million or FTE) 

 

Southern Gulf catchments based on north-west Queensland I–O model 

 

Type of agricultural development 

 

Beef cattle 

Agriculture excluding beef cattle 

Aquaculture, forestry and fishing 

 

Additional incomes expected to flow to Indigenous households from development ($ million) 

25 

0.2 

0.1 

0.1 

50 

0.4 

0.1 

0.1 

100 

0.8 

0.3 

0.3 

200 

1.6 

0.6 

0.6 

 

Additional incomes expected to flow to non-Indigenous households from development ($ million) 

25 

3.5 

5.0 

2.9 

50 

7.0 

10.0 

5.9 

100 

14.0 

20.1 

11.8 

200 

28.0 

40.2 

23.5 

 

Additional jobs estimated to be created (FTE) 

25 

53 

73 

43 

50 

107 

147 

87 

100 

213 

294 

174 

200 

427 

588 

347 



6.6 References 

ABS (2021) Water account, Australia, 2019–20 financial year. Australian Bureau of Statistics, 
Canberra. Viewed 19 December 2022, Hyperlink to: WAter account, Australia, 2019-20 financial year
. 

ABS (2022) Value of agricultural commodities produced, Australia 2021–22. Australian Bureau of 
Statistics, Canberra. Viewed 19 December 2022, Hyperlink to: Agricultural commodities, Australia
. 

AIHW (2023) Australia’s hospitals at a glance: web report. Australian Institute of Health and 
Welfare, Canberra. Viewed 1 March 2023, Hyperlink to: Australia's hospitals at a glance: web report
. 


Ansar A, Flyvbjerg B, Budzier A and Lunn D (2014) Should we build more large dams? The actual 
costs of hydropower megaproject development. Energy Policy 69, 43–56. Hyperlink to: Should we build more large dams? The actual costs of hydropower megaproject development
. 

Ash A, Gleeson T, Cui H, Hall M, Heyhoe E, Higgins A, Hopwood G, MacLeod N, Paini D, Pant H, 
Poulton P, Prestwidge D, Webster T and Wilson P (2014) Northern Australia: food and fibre 
supply chains study project report. CSIRO and ABARES, Australia. Viewed 13 September 
2024. https://www.csiro.au/en/research/natural-environment/land/food-and-fibre 

CRCNA (2020). Northern Australian broadacre cropping situational analysis. ST Strategic Services 
and Pivotal Point Strategic Directions (Issue July). Cooperative Research Centre for 
Developing Northern Australia, Townsville. Viewed 13 September 2024. 
https://crcna.com.au/wp-content/uploads/2024/05/NA-Cropping-situational-August.pdf 

Devlin K (2024) Conceptual arrangements and costings of hypothetical irrigation developments in 
the Victoria and Southern Gulf catchments. A technical report from the CSIRO Victoria and 
Southern Gulf Water Resource Assessments for the National Water Grid. CSIRO, Australia. 

Flyvbjerg B, Holm MS and Buhl S (2002) Underestimating costs in public works projects: error or 
lie? Journal of the American Planning Association 68(3), 279–295. Hyperlink to: Underestimating costs in public works projects: error or lie? 


Infrastructure Australia (2021a) Post completion review. Stage 4 of the Assessment Framework. 
Infrastructure Australia, Canberra. Viewed 1 March 2023, Hyperlink to: Post completion review. Stage 4 of the Assessment Framework
. 

Infrastructure Australia (2021b) Guide to economic appraisal. Technical guide of the Assessment 
Framework. Infrastructure Australia, Canberra. Viewed 1 March 2023, Hyperlink to: Guide to economic appraisal
. 

Jarvis D, Stoeckl N, Hill R and Pert P (2018) Indigenous land and sea management programs: can 
they promote regional development and help ‘close the (income) gap’? Australian Journal of 
Social Issues 53(3), 283–303. Hyperlink to: Indigenous land and sea management programs: can they promote regional development and help ‘close the (income) gap’? 


NWGA (National Water Grid Authority) (2022) National Water Grid investment framework. 
Australian Government Department of Climate Change, Energy, the Environment and Water, 
Canberra. Viewed 1 March 2023, Hyperlink to: National Water Grid Investment Framework
. 

NWGA (National Water Grid Authority) (2023) Project administration manual: National Water Grid 
Fund. Australian Government Department of Climate Change, Energy, the Environment and 
Water, Canberra. Viewed 1 March 2023, https://www.nationalwatergrid.gov.au/framework. 

Odeck J and Skjeseth T (1995) Assessing Norwegian toll roads. Transportation Quarterly 49(2), 89–
98. Viewed 13 September 2024. Hyperlink to: Assessing Norwegian toll roads 


Office of the Government Statistician Queensland Government (2004) Queensland regional input–
output tables 1996–97 34 industries. Queensland Government, Brisbane. 

Petheram C, and McMahon TA (2019) Dams, dam costs and damnable cost overruns. Journal of 
Hydrology X 3, 100026. Hyperlink to: Dams, dam costs and damnable cost overruns
. 


Stokes C and Jarvis D (2021) Economic assessment. In: Petheram C, Read A, Hughes J, Marvanek S, 
Stokes C, Kim S, Philip S, Peake A, Podger G, Devlin K, Hayward J, Bartley R, Vanderbyl T, 
Wilson P, Pena Arancibia J, Stratford D, Watson I, Austin J, Yang A, Barber M, Ibrahimi T, 
Rogers L, Kuhnert P, Wang B, Potter N, Baynes F, Ng S, Cousins A, Jarvis D and Chilcott C. An 
assessment of contemporary variations of the Bradfield Scheme. A technical report to the 
National Water Grid Authority from the Bradfield Scheme Assessment. CSIRO, Canberra. 
Viewed 13 September 2024. 
https://publications.csiro.au/publications/publication/PIcsiro:EP2021-2556 

Stokes C, Jarvis D, Webster A, Watson I, Jalilov S, Oliver Y, Peake A, Peachey A, Yeates S, Bruce C, 
Philip S, Prestwidge D, Liedloff A and Poulton P (2023) Financial and socio-economic viability 
of irrigated agricultural development in the Roper catchment. A technical report from the 
CSIRO Roper River Water Resource Assessment for the National Water Grid. CSIRO, 
Australia. Viewed 13 September 2024. 
https://publications.csiro.au/publications/publication/PIcsiro:EP2024-1414 

Vanderbyl T (2021) Southern Gulf: Queensland water plans and settings. A report from the CSIRO 
Southern Gulf Water Resource Assessment to the Government of Australia. CSIRO, Australia. 

Wachs M (1990) Ethics and advocacy in forecasting for public policy. Business and Professional 
Ethics Journal 9(1), 141–157. Hyperlink to: Ethics and advocacy in forecasting for public policy 


Webster A, Jarvis D, Jalilov S, Philip S, Oliver Y, Watson I, Rhebergen T, Bruce C, Prestwidge D, 
McFallan S, Curnock M and Stokes C (2024) Financial and socio-economic viability of 
irrigated agricultural development in the Southern Gulf catchments. A technical report from 
the CSIRO Southern Gulf Water Resource Assessment for the National Water Grid. CSIRO, 
Australia. 

Western Australian Auditor General (2016) Ord-East Kimberley Development. Report 20: 
September 2016. Office of the Auditor General Western Australia, Perth. Viewed 15 
December 2022, Hyperlink to: Ord-East Kimberley Development
. 

World Commission on Dams (2000) Dams and development. A new framework for decision 
making. Retrieved from Earthscan Publications Ltd, UK. Viewed 20 December 2022, Hyperlink to: Dams and development. A new framework for decision making
. 

Yang A, Petheram C, Marvanek S, Baynes F, Rogers L, Ponce Reyes R, Zund P, Seo L, Hughes J, 
Gibbs M, Wilson PR, Philip S and Barber M (2024) Assessment of surface water storage 
options in the Victoria and Southern Gulf catchments. A technical report from the CSIRO 
Victoria River and Southern Gulf Water Resource Assessments for the National Water Grid. 
CSIRO Australia 

 


7 Ecological, biosecurity, off-site and irrigation-
induced salinity risks 

Rob Kenyon, Rocio Ponce Reyes, Danial Stratford, Linda Merrin, Lynn Seo, Matt Gibbs, Simon Linke, 
Justin Hughes, Heather McGuinness, Ian Watson, Cuan Petheram, Peter Zund, John Virtue, 
Katie Motson 

 
Chapter 7 discusses a range of potential risks to be considered before establishing a greenfield 
agriculture or aquaculture development. These include ecological implications of altered flow 
regimes, biosecurity considerations, irrigation drainage and aquaculture discharge water, and 
irrigation-induced salinity. 

The key components and concepts of Chapter 7 are shown in Figure 7-1. 

 

Figure 7-1 Schematic diagram of the components where key risks can manifest when considering the establishment 
of a greenfield irrigation or aquaculture development 

For more information on this figure please contact CSIRO on enquiries@csiro.au
Numbers in blue refer to sections in this report. 

 


7.1 Summary 

This chapter provides information on the ecological, biosecurity, off-site and downstream impacts 
and irrigation-induced salinity risks to the catchments of the Southern Gulf rivers – that is, 
Settlement Creek, Gregory–Nicholson River and Leichhardt River, the Morning Inlet catchments 
and the Wellesley island groups1 – from greenfield agriculture or aquaculture development. It is 
principally concerned with the risks from these developments to the broader environment but 
also considers biosecurity risks to the enterprises themselves. 

1 Only those islands greater than 1000 ha are mapped 

The ecological impacts of vegetation clearing associated with irrigated agriculture are not explicitly 
examined in the Assessment as it is considered of secondary concern to potential impacts on 
water dependent ecological assets. This is because irrigated agriculture occupies a very small 
proportion of the landscape (typically less than 0.5%) but can result in a disproportionately high 
degree of regulation of river flow. Consequently, the Assessment placed greatest effort in 
understanding the potential ecological impacts of changes in streamflow on aquatic dependent 
ecosystems. 

7.1.1 Key findings 

Ecological implications of altered flow regimes 

The freshwater, terrestrial and near-shore marine zones of the Southern Gulf catchments contain 
important and diverse species, habitats, industries and ecosystem functions supported by the 
patterns, volumes and quality of river flows. Although irrigated agriculture only occupies a small 
percentage of the landscape, changes in the flow regime can have profound effects on flow-
dependent flora and fauna, their habitats and ecosystem service provision. These effects may 
extend considerable distances onto the floodplain and downstream, including into the marine 
environment. 

Hypothetical future scenarios for water harvesting, instream dams and groundwater development 
produced a range of water volumes and patterns of flow with a variety of impacts on ecology. The 
findings are summarised below: 

• The level of impact resulting from water resource development was highly dependent on the 
type of development, the extraction volume and the mitigation measures implemented. For 
most assets, water extraction had negligible to minor impacts on key aspects of river flows. 
• Large instream dams had a greater mean impact on surface-flow-dependent ecology averaged 
across the Southern Gulf catchments than did water harvesting. Large instream dams resulted in 
significantly larger local impacts on flow ecology in reaches below the dam wall than did water 
harvesting. A dam on the perennial Gregory River had major impacts on downstream flows that 
were important to several species or groups, while a dam on Gunpowder Creek, a major 
tributary of the Leichhardt River, had negligible to minor impacts on important flows for most 
assets. 



• Mitigation measures can reduce the negative impacts of flow modification on catchment 
ecology and key biota by maintaining aspects of flow that have been identified as critical to 
ecosystem service provision. Mitigation strategies, such as transparent flows (environmental 
flows that pass the dam wall) from dams that mimic historical flow patterns, guaranteed annual 
end-of-system flow volume prior to water extraction, and river flow pump-initiation thresholds 
below which water extraction cannot occur have been identified as effective in reducing risks. 


Water harvesting outcomes were sensitive to the volume of extraction. Mitigation measures also 
changed ecology outcomes across the Southern Gulf catchments, with mitigation reducing the 
effect on flows from moderate to minor, or minor to negligible. Harvesting 50 to 300 GL of water 
resulted in negligible to minor changes to most asset means across the catchments with impacts 
often accumulating downstream past multiple extraction points. Threadfin, prawn species, mud 
crabs and mullet were among the ecological assets most affected by flow change for water 
harvesting (moderate change). For low water harvest extraction volumes, suitable levels of end-of-
system flow requirements, commence-to-pump thresholds and pump rates improved mean 
outcomes across ecological assets and negligible change at catchment scales. Mitigation strategies 
demonstrate the importance of protecting minimum flows and annual ‘first flows’ for many of the 
ecological assets and that deployment of mitigation has considerable potential to reduce impacts 
on water-dependent ecosystems. 

For instream dams, the location of the dam in the catchment matters as there is potential for 
extreme risks of local impacts. Improved outcomes were associated with maintaining attributes of 
the natural flow regime via the provision of transparent flows. A single dam on either Gunpowder 
Creek or the Gregory River resulted in negligible to minor (respectively) mean change to assets 
flows at the catchment scale, but local impacts were often with considerably higher and reached 
extreme levels. Mangroves, mullet, cryptic wader birds, prawns and mud crabs were among the 
ecological assets most affected by instream dams. Providing transparent flows (environmental 
low-flows) improved flow regimes for ecological service provision at both local and catchment 
scales: mean outcomes for mangroves could be improved from major to moderate mean change, 
and outcomes for catfish, cryptic wader birds and inchannel waterhole assets from moderate to 
minor mean change across the catchment. 

Beyond flow, other impacts and considerations are also important. At catchment scales, the direct 
impacts of irrigation on the terrestrial environment are typically small. However, indirect impacts, 
such as weeds, pests and landscape fragmentation, particularly to riparian zones, and changes in 
fire regimes may be considerable. Changes in water quality may also affect ecology but are not 
considered in the quantitative analysis. The combined changes of a potentially drier future climate 
and hypothetical water resource development produced greater impacts than did each factor on 
its own. 

Biosecurity considerations 

Biosecurity is the prevention and management of pests, weeds and diseases, both terrestrial and 
aquatic, to limit their economic, environmental, social and cultural impacts. Economic impacts 
include reduced crop yield and product quality, interference with farming operations, loss of 
market access and costs of implementing control measures. Environmental impacts include loss of 
biodiversity and changes to ecosystem processes such as fire regimes. Social and cultural impacts 
of pests, weeds and diseases include diminished value of areas for recreational or traditional uses. 


Despite its relative isolation, there are many human-mediated and natural pathways by which 
pests, weeds and diseases can spread to and within the Southern Gulf catchments. New pests, 
weeds and diseases may spread from adjacent regions, other parts of Australia or even 
neighbouring countries. Biosecurity is a shared responsibility that requires governments, 
industries and the community to each take steps to limit the introduction and spread, detect and 
respond to incursions, and manage the impacts of key biological threats. A further complication 
for the cross-border catchment is being aware of biosecurity requirements for both the NT and 
Queensland, including the latter’s general biosecurity obligation. 

A range of current and potential pests, weeds and diseases could affect irrigated cropping in the 
Southern Gulf catchment. These include fall armyworm (Spodoptera frugiperda), which consumes 
C4 grass crops; cucumber green mottle mosaic virus, which infects a wide range of cucurbit crops; 
incursion risks from overseas such as citrus canker (Xanthomonas citri subsp. citri) and exotic fruit 
flies; and parthenium weed (Parthenium hysterophorus), which is a crop competitor, seed 
contaminant and allergen. Farm biosecurity planning to identify, prevent, detect and manage key 
pest, weed and disease threats is fundamental to a successful enterprise. Such planning includes 
following government and industry best practice regarding movement of plants, plant products 
and machinery, control of declared species, pesticide use, farm stewardship and market access 
requirements. 

Preventive biosecurity practices are crucial in aquaculture facilities as diseases can be difficult to 
eliminate. There are many diseases of production concern, whether overseas, having entered 
Australia (e.g. white spot syndrome virus of crustaceans) or naturally occurring in Australian 
ecosystems. Aquaculture biosecurity planning needs to consider hygiene actions needed for key 
pathways of disease entry, early detection and diagnosis, quarantining and treatment. 

Invasive species, whether pest, weed or disease, are commonly characterised as occurring across 
multiple land uses in a landscape. Their impacts will vary between land uses, but their coordinated 
control requires action across all tenures. Various high-impact weeds listed as declared (NT) or 
restricted (Queensland) are present in, or threaten to invade, the Southern Gulf catchments, 
including aquatic plants, grasses, shrubs and trees. There are also pest vertebrates (e.g. large feral 
herbivores, exotic fish), pest invertebrates (e.g. exotic ants) and plant pathogens (e.g. 
Phytophthora) that can cause disease. NT and Queensland government legal requirements to 
prevent or control invasive pests, weeds and diseases need to be followed. Regional and local 
irrigation and industry infrastructure development, including road networks, should include 
prevention and management of invasive species in their environmental planning processes. Choice 
of crops and aquaculture species should also consider the invasive risk and any management 
required to prevent their spread into the environment. 

Off-site and downstream impacts 

Agriculture can affect the water quality of downstream freshwater, estuarine and marine 
ecosystems. The principal pollutants from agriculture are nitrogen, phosphorus, total suspended 
solids, herbicides and pesticides. Most of the science in northern Australia concerned with the 
downstream impacts of agricultural development has been undertaken in the eastern-flowing 
rivers that flow into the Great Barrier Reef lagoon. Comparatively little research on the topic has 
been done in the rest of northern Australia. 


Degraded water quality can cause a loss of aquatic habitat, biodiversity and ecosystem services. 
Increased nitrogen and phosphorus can cause plankton blooms and weed infestation, increase 
hypoxia (low oxygen levels) and result in fish deaths. Pesticides, used to increase agricultural 
productivity, can harm downstream aquatic ecosystems, flora and fauna. Fertiliser nutrients and 
pesticides can enter surface water bodies and groundwater via infiltration, leaching, and runoff 
from rainfall events and irrigation. 

Losses via runoff or deep drainage are the main pathways by which agricultural pollutants enter 
water bodies. Management of irrigation or agricultural drainage waters is a key consideration 
when evaluating and developing new irrigation systems, and it should be given careful 
consideration during the planning and design process. Seasonal hydrology, particularly ‘first-flush’ 
events following irrigation or significant rainfall, plays a critical role in determining water quality. 
Studies have shown that pesticide concentrations in runoff are highest following initial irrigation 
events but decrease in subsequent events. Similarly, nitrogen concentrations in runoff are often 
higher following early-season rainfall, when crops have not yet fully absorbed available nitrogen, 
leading to increased transport in runoff. Minimising drainage water by using best-practice 
irrigation design and management should be a priority in any new irrigation development in 
northern Australia. 

While elevated contaminants and water quality parameters can harm the environment and human 
health, there are several processes by which aquatic ecosystems can partially process 
contaminants and regulate water quality. Denitrification is a natural process that can remove and 
reduce nitrogen concentrations within a water body. Phosphorus, however, does not have a 
microbial reduction process equivalent to denitrification. Instead, if it is not temporarily taken up 
by plants, phosphorus can be adsorbed onto the surface of inorganic and organic particles and 
stored in the soil, or deposited in the sediments of water bodies, such as wetlands. 

Aquaculture can be affected by poor water quality and can also contribute to poor water quality 
unless aquaculture operations are well managed. Aquaculture species are particularly vulnerable 
to some of the insecticides and other chemicals used in agricultural, horticultural and mining 
sectors, and in industrial and domestic settings. Aquaculture management is designed to discharge 
water that contains low amounts of nutrients and other contaminants. The aim is for discharge 
waters to have similar physiochemical parameters to the source water. Because aquaculture 
management in northern Australia has largely been developed to ensure that the waters of the 
Great Barrier Reef lagoon do not receive excessive contaminants, there is considerable experience 
in operating aquaculture enterprises in northern Australia under world’s best practice. 

Irrigation-induced salinity 

Naturally occurring areas of salinity, or ‘primary salinity’, occur in the landscape, and their ecosystems 
are adapted to the saline conditions. Any change to landscape hydrology, including clearing and 
irrigation, can mobilise salts, resulting in environmental degradation in the form of ‘secondary salinity’. 
This occurs where rising groundwater mobilises salts in the soil and substrate materials, moving 
the salts into the plant root zone and/or discharging salts on lower slopes, in drainage depressions 
or in nearby streams. Soil knowledge and best-practice management of irrigation timing and 
application rates can reduce the risk of irrigation-induced salinity. 


Note that the material in this chapter provides general information regarding soils suitable for 
irrigation development. The risk of secondary salinisation at a specific location in the Southern 
Gulf catchments can only be properly assessed by undertaking detailed field investigations at a 
local scale. 

Existing salinity is not prominent in the Assessment area apart from the salt plains along the coast, 
which are not considered for irrigation development. However, the cracking clay soils on the 
Armraynald Plain, particularly the black soils along the Gregory River backplain, have subsoils that 
are high in salt and susceptible to irrigation-induced secondary salinity. These cracking clay soils 
can be successfully irrigated if they can be managed to prevent waterlogging and the mobilisation 
of salts in the profile. The clay soils (soil generic group (SGG) 9, see Section 2.3) on the Barkly 
Tableland have low subsoil salt levels. Where they are underlain by porous limestone and 
dolomite, a build-up of salts due to irrigation is not expected. 

The sandy, loamy and sand or loam over friable brown, yellow and grey clay soils on the 
Doomadgee Plain also have negligible salts within the soil profile. However, due to other risk 
factors, care would need to be exercised when clearing the silver box, bloodwood and broad-leaf 
paperbark savanna landscapes for rainfed or irrigated cropping. Groundwater aquifers contained 
by underlying ferricrete, the likelihood of soils having variable depths, and the very gently 
undulating plain make it difficult to manage irrigation water discharge on lower slopes and in 
drainage depressions, causing salts to accumulate in these areas in the long term. In places where 
these soils are shallow, it would be necessary to monitor the depth of watertables and manage 
irrigation rates accordingly. In addition, over-irrigation is likely to have off-site impacts in the long 
term, as the lateral flow of water can ‘wick’ from the lower slopes in these landscapes to form 
scalds. From these scalds, salts can potentially be mobilised towards nearby streams. 

7.2 Introduction 

Water and irrigation development can result in complex and, in some cases, unpredictable 
changes to the surrounding environment and communities. For instance, before the construction 
of the Burdekin Falls Dam, the Burdekin Project Committee (1977) and Burdekin Project Ecological 
Study (Fleming et al., 1981) concluded that the dam would improve water quality and clarity in the 
lower river and that para grass (Brachiaria mutica), an invasive weed from Africa that was then 
present at relatively low levels, could become a useful ecological element as a result of increased 
water delivery to the floodplain. However, the Burdekin Falls Dam has remained persistently 
turbid since construction in 1987, greatly altering the water quality and ecological processes of the 
river below the dam and the many streams and wetlands into which that water is pumped on the 
floodplain (Burrows and Butler, 2007). Para grass and, more recently, hymenachne (Hymenachne 
amplexicaulis), an ecologically similar plant from South America, have become serious weeds of 
the floodplain wetlands, rendering innumerable wetlands unviable as habitat for most aquatic 
biota that formerly occurred there (Tait and Perna, 2001; Perna, 2003, 2004). 

Thus, there are limitations to the advice that can be provided in the absence of specific 
development proposals, so this section provides general advice on the considerations or 
externalities most strongly affected by water resource and irrigation developments. It is not 
possible to discuss every potential change that could occur. In particular the ecological impacts of 
vegetation clearing associated with irrigated agriculture are not explicitly examined as it is 


considered of secondary concern to potential impacts on water dependent ecological assets. This 
is because irrigated agriculture occupies a very small proportion of the landscape (typically less 
than 0.5%) but can result in a disproportionately high degree of regulation of river flow. 
Consequently, the Assessment placed greatest effort in understanding the potential ecological 
impacts of changes in streamflow on aquatic dependent ecosystems. It is noted, however, that 
areas of high agricultural potential may also be highly valued with respect to biodiversity 
conservation (Kutt et al., 2009). For these and other reasons the northern jurisdictions have formal 
processes in place for the approval (or not) of clearing native vegetation. Clearing approvals are 
only provided by the jurisdictions where they consider the ecological impact to be minimal given 
the extent and protection of vegetation type in the region (e.g. Queensland Government, 2023a). 

The remainder of the chapter is structured as follows: 

• Section 7.3 Ecological implications of altered flow regimes examines how river regulation affects 
inland and freshwater assets in the Southern Gulf catchments and marine assets in the near-
shore marine environment. It also examines how the impacts can be mitigated. 
• Section 7.4 Biosecurity considerations discusses the risks presented to an irrigation development 
by disease, pests and weeds, and the risks that new agriculture or aquaculture enterprise in the 
Southern Gulf catchments may present to the wider industry and broader catchment. 
• Section 7.5 Off-site and downstream impacts considers how agriculture can affect the water 
quality of downstream freshwater, estuarine and marine ecosystems. 
• Section 7.6 Irrigation-induced salinity briefly discusses the risk of irrigation-induced salinity to 
irrigation development and to the downstream environment in the Southern Gulf catchments. 


Other externalities associated with water resource and irrigation development discussed 
elsewhere in this report include the direct impacts of the development of a large dam and 
reservoir on: 

• Indigenous cultural heritage (Section 3.4) 
• water quality (Section 7.5) 
• the movement of aquatic species (Section 5.4) 
• terrestrial ecosystems within the reservoir inundation area (Section 5.4). 


These externalities are rarely factored into the true costs of water resource or irrigation 
development. Even in parts of southern Australia where data are more abundant, it is very difficult 
to express these costs in monetary terms, as perceived changes are strongly driven by values, 
which can vary considerably within and between communities and fluctuate over time. Therefore, 
the material in this chapter is presented as a stand-alone analysis to help inform conversations 
and decisions between communities and government. 

Note that this chapter primarily focuses on key risks resulting from irrigated agriculture and 
aquaculture, although the section on biosecurity considers both risks to the enterprise and risks 
emanating from the enterprise into the broader environment. Other risks to irrigated agriculture 
and aquaculture are discussed elsewhere in this report, including risks associated with: 

• flooding (Section 2.5) 
• sediment infill of large dams (Section 5.4) 



• reliability of water supply (sections 5.4 and 6.3) 
• timing of runs of failed years on the profitability of an enterprise (Section 6.3). 


Material within this chapter is largely based on the companion technical reports on ecology 
(Merrin et al., 2024; Ponce Reyes et al., 2024) but also draws upon findings presented in the 
Northern Australia Water Resource Assessment technical reports on agricultural viability (Ash et 
al., 2018) and aquaculture viability (Irvin et al., 2018). Further information can be found in those 
reports. 

7.3 Ecological implications of altered flow regimes 

7.3.1 Water resource development and flow ecology 

The ecology of a river is intricately linked to its flow regime, and its species are broadly adapted to 
the prevailing conditions under which they occur. Changes in freshwater flows can affect the 
persistence or ephemerality of rivers, the volumes of river flows, and patterns of floodplain 
inundation and discharges. These changes directly affect species, habitats and ecosystem 
functions. Freshwater-flow-dependent flora, fauna and habitats are defined here as those 
sensitive to changes in flow and sustained by either surface water or groundwater flows or a 
combination of both. In rivers and floodplains, activities like water capture, storage, release, 
conveyance and extraction can significantly alter the environmental ecohydrology on which rivers 
function. Water regulation is frequently considered one of the biggest threats to aquatic 
ecosystems worldwide (Bunn and Arthington, 2002; Poff et al., 2007). Water resource 
development can cause changes in flow during both wet and dry periods, including the magnitude, 
timing, duration and frequency of flows (Jardine et al., 2015; McMahon and Finlayson, 2003). 
These changes can affect flora, fauna and habitats, and effects often extend far downstream, 
reaching near-shore coastal and marine areas as well as floodplains (Burford et al., 2011; Nielsen 
et al., 2020; Plagányi et al., 2024; Pollino et al., 2018). Water resource development can also result 
in changes to water quality, which is discussed in Section 7.5. 

The environmental risks associated with water resource development are particularly complex in 
northern Australia. This is in part because of the diversity of species and habitats distributed 
across and within the catchments and near-shore zones. In addition, wet-season precipitation is 
critical to sustain the ecology of Southern Gulf landscapes throughout the approximately 8-month 
annual dry season (Section 2.4). From the ecosystem scale, such as the coastal 
mangrove/estuary/salt flat complex, to the microhabitat scale, such as riverine pond refugia, 
communities and species depend on wet-season rainfall and runoff to invigorate the catchment-
to-coast ecosystem following 9 months of negligible rainfall, high evaporation and no freshwater 
runoff or inflows (Duke et al., 2019; McJannet et al., 2014). Across northern Australia, monsoon 
rains relieve the extended period of dry conditions in the landscape (Petheram et al., 2008; 
Petheram et al., 2012). As a result, water resource development can divert water critical for 
ecosystem services, leading to a wide range of direct and indirect environmental impacts. 

Impacts on flow-dependent species and habitats can include flow regime change, loss of habitat, 
loss of function (such as connectivity), changes to water quality and the establishment of pest 
species. Instream dams create large bodies of standing water that inundate terrestrial habitat and 


result in the loss of the original stream and riverine conditions (Nilsson and Berggren, 2000; 
Schmutz and Sendzimir, 2018). Dams can capture flood pulses and reduce the volume and extent 
of water that transports important nutrients into estuaries and coastal waters via flood plumes 
(Burford et al., 2016; Burford and Faggotter, 2021; Tockner et al., 2010). Even minor instream 
barriers, such as road causeways, can disrupt migration and movement pathways, causing 
fragmentation of populations and loss of essential habitat for species that need passage along the 
river (Crook et al., 2015; Pelicice et al., 2015). Increased human activity associated with water 
resource development, such as irrigation, can introduce additional pressures, including biosecurity 
risks from invasive species that may spread into new or modified habitats or may be at increased 
risk of establishment (Pyšek et al., 2020). 

This section provides an analysis of the risks associated with flow regime change in the Southern 
Gulf catchments to freshwater, estuarine and near-shore marine ecology and terrestrial systems 
dependent upon river flows. The impacts of habitat loss within hypothetical dam impoundments 
and of loss of connectivity due to the development of new instream barriers and impact 
associated with land use change due to the creation of an impoundment are discussed in the 
companion technical report (Yang et al., 2024). Existing and other potentially threatening 
processes for ecological assets, including their possible synergistic impacts, are discussed 
qualitatively in the companion ecological descriptions report (Merrin et al., 2024). For more details 
of the ecological asset analysis and details of analysis for all assets, see Ponce Reyes et al. (2024). 

7.3.2 Ecology of the Southern Gulf catchments 

The Southern Gulf catchments span 108,200 km² across the NT and Queensland, encompassing 
several significant protected areas (Merrin et al., 2024). These areas feature national parks like 
Boodjamulla and Finucane Island national parks, and 13 wetlands listed in the Directory of 
Important Wetlands in Australia. Among these wetlands is the Southern Gulf Aggregation (the 
largest continuous estuarine wetland in Australia), where the Gregory River crosses the Nicholson 
River Basin and Leichhardt River Basin (the largest perennial river in semi-arid and arid 
Queensland), and the Wentworth Aggregation (Department of Agriculture‚ Water and the 
Environment, 2021). 

The ecology of the Southern Gulf catchments is shaped by its wet-dry tropical climate, 
characterised by an extended dry season and a wet season during which the most rainfall occurs. 
In the dry season, river flows decrease and many of the catchment’s streams recede into isolated 
waterholes. However, in parts of the catchment, water persists during the dry season, supported 
by groundwater-fed perennial rivers like the Gregory and O’Shannassy rivers and Lawn Hill Creek, 
along with other water sources such as creeks, permanent lakes and inchannel waterholes. These 
water sources provide essential refuge habitats for a diverse array of aquatic species, particularly 
in this semi-arid environment (McJannet et al., 2023; Waltham et al., 2013). 

A significant landscape within the Southern Gulf catchments is the low-gradient, tidally influenced 
coastline characterised by some of the most extensive supratidal salt flats and chenier plain 
formations of the Australian coastline (Short, 2020). The salt flats are fronted by a beach-barrier 
shoreline (west of Mornington Island, 87% of the coastline is sand beach) and mangrove-fringed 
mudflats (east of Mornington Island, 13.5% of the coastline is sand beach). The salt flat complex is 
most extensive east of Mornington Island and can extend 30 to 50 km inland. It is dissected by 


several major rivers and multiple mangrove-lined creeks, creating a distinctive supra-littoral and 
littoral estuarine and marine environment that provides critical habitat to many species. The 
coastal ecosystem is characterised by an extremely low gradient, both in terrestrial habitats 
landward of the salt flat complex and in intertidal and subtidal habitats to seaward, contributing to 
the southern gulf of Carpentaria coastline being the most low-energy region of the open 
Australian coastline (Short, 2020). 

Within the multiple estuaries, mangrove forests, intertidal and supratidal sea-flats of the coastal 
zone of the Southern Gulf catchments, primary production from microalgae within the estuarine 
water column and subtidal, intertidal and supratidal sediments rivals productivity from other 
sources, such as the macrophytes (Burford et al., 2016; Burford et al., 2012). Annual flood flows 
deposit thousands of tonnes of nitrogen and phosphorus within flood plumes into the Gulf of 
Carpentaria, particularly in years of high floods (Burford et al., 2012; Burford and Faggotter, 2021). 
In addition, annual wetting of the salt flats due to rainfall and overbank flows invigorate extensive 
senescent algal crusts that cover the hundreds of square kilometres of salt flats, contributing an 
additional 13% to the primary productivity of estuarine/salt flat complex of the southern Gulf of 
Carpentaria (Burford et al., 2016). Primary productivity contributes to populations of mollusc, 
crustacean and annelid meiofauna and macrobenthos within estuarine and coastal sediments of 
the Southern Gulf (Lowe et al., 2022; Venarsky et al., 2022), forming the basis of the coastal food 
web. The volume and persistence of wet- and dry-season river flows have strong influences on the 
abundance and species diversity of infauna within estuarine and shallow coastal sandflats (Duggan 
et al., 2014; Lowe et al., 2022). 

This coastal matrix ecosystem is critical habitat for many bird, reptile, fish and crustacean species. 
Wader birds that migrate between the northern and southern hemispheres use the littoral 
habitats of Southern Gulf catchments as a crucial stopover on their biannual flyway (Garnett, 
1987; Tait, 2005). Many of the bird species are threatened, endangered or critically endangered. 
Key fish species such as barramundi, threadfin, barred-grunter, sawfish, mullet and catfish, as well 
as crustaceans such as cherubin (in the brackish ecotone), mud crabs and multiple species of 
penaeid prawns, are abundant within estuarine and coastal habitats (Leahy and Robins, 2021; 
Robins et al., 2020; Staples and Vance, 1986). Freshwater and saltwater crocodiles are common 
within the catchments (Read et al., 2004). 

During the wet season, significant flooding occurs in the Southern Gulf catchments, inundating 
floodplains and connecting wetlands to the river channels, which enhances primary and secondary 
productivity. This process is particularly notable in the lower parts of the catchment, including the 
floodplain wetlands and the extensive intertidal salt flats along the mainland coastline, particularly 
south of Bentinck and Sweers islands. These nutrient-laden flood discharges into the marine 
waters of the south-western Gulf of Carpentaria support high levels of marine productivity, which 
in turn sustains important fisheries and ecological processes. 

The Southern Gulf catchments have high biodiversity. They support at least 170 species of fish, 
150 species of waterbirds, 30 species of aquatic and semi-aquatic reptiles, 60 species of 
amphibians and 100 macroinvertebrate families (van Dam et al., 2008b). Notable species include 
the freshwater or largetooth sawfish (Pristis pristis; listed as Vulnerable under the Commonwealth 
Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)) and the Gulf snapping 
turtle (Elseya lavarackorum; Endangered). The catchments also serve as crucial stopover habitats 


















for migratory shorebird species listed under the EPBC Act, including the eastern curlew (Numenius 
madagascariensis; Critically Endangered) and the Australian painted snipe (Rostratula australis; 
Endangered). 
The ecology of the Southern Gulf catchments is further detailed in the companion report on 
ecological assets (Merrin et al., 2024). 
7.3.3 Scenarios of hypothetical water resource development and future climate 
The ecology analysis used modelled hydrology from a river model for the Gregory– Nicholson and 
Leichhardt catchments (see companion technical reports on river model calibration and simulation 
(Gibbs et al., 2024a,b)) to explore the possible impacts of water resource development in the 
Southern Gulf catchments using a range of hypothetical scenarios. The scenarios were configured 
to explore how different types and scales of water resource development, such as instream 
infrastructure (i.e. large dams) and water harvesting (i.e. pumping river water into offstream farm-
scale storages) affect water-dependent ecosystems. The impact of a hypothetical development on 
water-dependent ecological assets is inferred and reported here in terms of a catchment-
weighted, percentage change in key ‘flow dependencies’ (at key stages of the life cycle) relative to 
a baseline, averaged over the Assessment time period (i.e. 1 September 1890 to 31 August 2022). 
The catchment-weighted value is calculated by spatially weighting percentage change in key flow 
dependency calculations using the modelled likely habitat of each asset across the study area. This 
is referred to as the spatially weighted mean impact on key flow dependencies. The ecological 
analysis used Scenario AE as a reference (Section 1.4.3), recognising that current conditions likely 
reflect a stabilised state following past development in the catchments (Gibbs et al., 2024b). 
Changes in flow dependencies do not necessarily correlate with changes in asset condition, as this 
depends on the relative importance of river flow compared to other factors such as rainfall, soil 
water, groundwater and local runoff. 
Section 1.2.2 discusses the plausibility of development pathways and should be consulted when 
evaluating the likelihood of a hypothetical development scenario occurring. Broad scenario 
definitions used in the Assessment are described in Section 1.4.3 and summarised in Table 7-1. 
The scenarios were chosen to cover a range of potential ecological outcomes for the selected 
assets. The location of the river modelling nodes referred to in this section are shown in Figure 
7-2. Further details of the river system model simulations are provided in the companion technical 
report on river model simulation (Gibbs et al., 2024b).
Key terms used in Section 7.3 
Water harvesting – an operation where water is pumped or diverted from a river into an 
offstream storage. 
Offstream storages – usually fully enclosed, circular or rectangular earthfill embankment 
structures situated close to major watercourses or rivers to minimise the cost of pumping. 
Large engineered instream dams – usually constructed from earth, rock or concrete materials as a 
barrier across a river to store water in the reservoir created and intercept a drainage line (Yang et 
al., 2024). 


Annual diversion commencement flow requirement (DCFR) – the cumulative volume passing the 
most downstream node in catchments with water harvest (on the Leichhardt River node 9130071, 
Albert River node 9129040 and Nicholson River node 9121090) from the start of the water year 
that is required before water harvest pumping can commence. 

Pump-start threshold – a daily flow threshold above which pumping or diversion of water can 
commence. This is usually implemented as a strategy to minimise the ecological impact of water 
harvesting. 

Pump capacity – the capacity of the pumps expressed as the number of days it would take to 
pump the entire node irrigation target. 

Reach irrigation volumetric target – the maximum volume of water extracted in a river reach over 
a water year. Note that the end use need not be irrigation; users could also be involved in 
aquaculture, mining, urban or industrial activities. 

System irrigation volumetric target – the maximum volume of water extracted across the entire 
study area over a water year. Note that the end use need not be irrigation; users could also be 
involved in aquaculture, mining, urban or industrial activities. 

Transparent flow – a strategy to mitigate the ecological impacts of large instream dams by 
allowing all reservoir inflows below a flow threshold to pass ‘through’ the dam. 

Note that each potential water resource development pathway results in different changes to flow 
regimes. This is due to differences in rainfall and upstream catchment sizes, inflows, the 
attenuation of flow through the river system (including accumulating inflows with river 
confluences), and also the many ways each water resource development could unfold and be 
implemented and managed. These scenarios were not analysed because they were considered 
likely or recommended by CSIRO; rather, they were selected to explore some of the interactions 
between location and the types and scale of development, to provide insights into how different 
types and scales of water resource development and mitigation measures may influence ecology 
outcomes across the catchment. 

Some of the hypothetical scenarios listed in Table 7-1 provide the minimum level of dedicated 
environmental provisions and have been optimised for water yield reliability, without considering 
policy settings or additional restrictions that may help mitigate the impacts on water-dependent 
ecosystems. These scenarios are useful for considering impacts across various development 
strategies in the absence of mitigation strategies or policy settings (or could be representative of 
regulatory non-compliance). Furthermore, management and regulatory requirements in a real-
world setting would likely provide a range of safeguards for environmental outcomes, possibly 
establishing a combination of transparent flows (river flows that are managed to pass a regulating 
structure to support ecology), end-of-system requirements, extraction limits and/or minimum 
flow thresholds. Each of these safeguards, if implemented, would likely improve the 
environmental outcomes. Furthermore, many of the scenarios explored, while technically feasible, 
exceed the level of development that would reasonably occur (see Section 1.2.2). These scenarios 
were included as a stress test of the system and can be useful for benchmarking or contrasting 
various levels of change. 

The development scenarios are hypothetical and are for the purpose of exploring a range of 
options and issues in the Southern Gulf catchments. In the event of any future development 


occurring, further work would need to be undertaken to assess environmental impacts associated 
with the specific development across a broad range of environmental considerations. 



River system model nodes, flow-ecology dependencies, map
\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\7_Ecology\4_S_Gulf\1_GIS\1_Map_docs\Ec-S-535_Potential dams and Nodes_v9.mxd
For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 7-2 Locations of the river system modelling nodes at which flow–ecology dependencies were assessed 
(numbered) and the locations of hypothetical water resource developments in the Southern Gulf catchments 

The flow ecology of the environmental assets was assessed in subcatchments downstream of the river system nodes. 
The locations of assets across the catchment are documented in Merrin et al. (2024). Marine assets used a combined 
end-of-system node (9100000), which combined flows from the Nicholson (9121090 and 9129040) and Leichhardt 
(9130071) rivers. 


Table 7-1 Water resource development and climate scenarios explored in this ecology analysis 

Gibbs et al. (2024a) and Gibbs et al. (2024b) describe the river system modelling and additional scenario details. 

SCENARIO 

DESCRIPTION 

ASSUMES 
FULL USE 
OF 
EXISTING 
LICENCES 

TRANSPARENT FLOW 
THRESHOLD 
(% OF MEAN 
INFLOW) 

TARGET 
EXTRACTION 
VOLUME (GL) 

ANNUAL 
DIVERSION 
COMMENCEMENT FLOW 
REQUIREMENT (GL) 

PUMP-START 
THRESHOLD 
(ML/d) 

PUMP 
CAPACITY 
(d) 

Scenario A 

Historical climate and 
no hypothetical 
development 













AN 

No development – 
natural conditions 

No (no 
use) 

na 

0 

na 

na 

na 

AE 

Current (2023) levels of 
development 

No 
(current) 
(29.9 GL) 

No 

0 

0 

variable 

variable 

A 

Full use of existing 
entitlements 

Yes 
(113.5 GL) 

No 

0 

0 

variable 

variable 

Scenario B 

Historical climate and 
hypothetical future 
development 













B-DGPC

B-DGR

Single hypothetical 
dams‡ 

Yes 
(113.5 GL) 

No 

na‡ 

na 

na 

na 

B-D2

Two hypothetical dams 
together (B-DGPC and B-
DGR)

 

Yes 
(113.5 GL) 

No 

na‡ 

na 

na 

na 

B-DGPCT

B-DGRT

Single hypothetical 
dams with transparent 
flows 

Yes 
(113.5 GL) 

Q = 20 

na‡ 

na 

na 

na 

B-D2T

Two hypothetical dams 
together with 
transparent flows (B-
DGPCT and B-DGRT) 

Yes 
(113.5 GL) 

Q = 20 

na‡ 

na 

na 

na 

B-WT150P600R30E0

Water harvesting 
varying target 
extraction volume (T), 
annual diversion 
commencement flow 
requirement (E), pump-
start threshold (P), 
and/or pump capacities 
(R) 

Yes 
(113.5 GL) 

na 

T = 50, 150, 
300 

E = 0, 150… 

P = 200, 
600… 

R = 10, 
20… 

Scenario C 

Future climate and 
current level of 
development 













CEdry 

Dry GCM†† projection 
(see Section 2.4.5) 

No 
(current) 
(29.9 GL) 

No 

0 

0 

variable 

variable 

Scenario D 

Future climate and 
hypothetical future 
development 













D-DGPC 

Single hypothetical 
dams‡ with Scenario 
Cdry 

Yes 
(113.5 GL) 

No 

na‡ 

na 

na 

na 




DESCRIPTION 

SCENARIO 

ASSUMES 
FULL USE 
OF 
EXISTING 
LICENCES 

TRANSPARENT FLOW 
THRESHOLD 
(% OF MEAN 
INFLOW) 

TARGET 
EXTRACTION 
VOLUME (GL) 

ANNUAL 
DIVERSION 
COMMENCEMENT FLOW 
REQUIREMENT (GL) 

PUMP-START 
THRESHOLD 
(ML/d) 

PUMP 
CAPACITY 
(d) 

D-D2

Two hypothetical dams 
(same as B-D2) with 
Scenario Cdry 

Yes 
(113.5 GL) 

No 

na‡ 

na 

na 

na 

D-D2T

Two hypothetical dams 
(same as B-D2) with 
Scenario Cdry with 
transparent flows 

Yes 
(113.5 GL) 

Q = 20 

na‡ 

na 

na 

na 

D-
WT150P600R30E0 

Water harvesting with 
Scenario Cdry 

Yes 
(113.5 GL) 

na 

T = 50, 150, 
300 

E = 0, 150, 
250… 

P = 200, 
600… 

R = 30… 



‡No target volume for hypothetical dam scenarios; instead a target extraction volume that could be met with 85% reliability was identified. 
††GCM = general circulation model. 
na = not applicable. 

7.3.4 Ecology outcomes and implications 

The ecology activity used an asset-based approach to analysis, building on the work of Pollino et 
al. (2018) and Stratford et al. (2024). For the Southern Gulf catchments, 21 ecological assets (Table 
7-2) were selected for analysis across 79 nodes, including the end-of-system node for near-shoremarine assets (Figure 7-2). Both the ecology asset descriptions technical report (Merrin et al.,
2024) and the ecology asset analysis technical report (Ponce Reyes et al., 2024) should beconsulted in conjunction with the material provided here.

The selected ecological assets encompass freshwater, marine and terrestrial habitats that depend 
on river flows to varying extents, and they were modelled with regards to changes to surface 
water. Assets were included if they were distinctive, representative, describable and significant 
within the catchment. The assets’ flow ecologies and locations were described in Merrin et al. 
(2024), which also provides species and habitat distribution maps, including species distribution 
models developed for many of the species. Each asset had different needs and linkages to the flow 
regime, and these assets occurred across different parts of the catchment or the near-shore 
marine zone. Understanding the flow ecology of assets and their locations across the catchment 
was important for identifying the potential risks of changes in catchment hydrology, as not all 
types of changes will affect assets equally. 


Table 7-2 Ecological assets used in the Southern Gulf catchments Water Resource Assessment and the different 
ecology groups used in this analysis 

Twenty-one assets are modelled in the ecology analysis; assets may be assigned to more than one group. Description 
of the ecological assets and their distribution is provided in Merrin et al. (2024). Assets marked with an asterisk are 
presented in this report. Analysis and interpretation for all assets is provided in Ponce Reyes et al. (2024). 

ASSET GROUP 

ASSET 

SYSTEMS 

Fish, sharks and rays 

Barramundi (Lates calcarifer) 

Freshwater and marine 



Bullshark 

Freshwater and marine 



Catfish (order Siluriformes) 

Freshwater 



Grunters (family Terapontidae) 

Freshwater 



Mullet (family Mugilidae) 

Freshwater and marine 



Sawfishes (Pristis and Anoxypristis spp.)* 

Freshwater and marine 



Threadfin (Polydactylus macrochir) 

Marine 

Waterbirds 

Colonial and semi-colonial nesting wading 
waterbirds 

Freshwater 



Cryptic wading waterbirds 

Freshwater 



Shorebirds 

Freshwater and marine 



Swimming, grazing and diving waterbirds* 

Freshwater 

Prawns, turtles and other 
species 

Banana prawns (Penaeus merguiensis) 

Marine 



Endeavour prawns (Metapenaeus endeavouri 
and M. ensis) 

Marine 



Tiger prawns (Penaeus semisulcatus and 
P.esculentus) 





Freshwater turtles (family Chelidae) 

Freshwater 



Mud crabs (Scylla serrata) 

Marine 

Flow-dependent habitats 

Floodplain wetlands* 

Freshwater 



Inchannel waterholes 

Freshwater 



Mangroves 

Marine 



Saltpans and salt flats 

Marine 



Seagrass 

Marine 



Surface-water-dependent vegetation 

Freshwater and terrestrial 



The flow dependencies (hydrometrics) modelling calculated for each asset an index of flow regime 
change resulting from the different scenarios using asset-specific hydrometrics using metrics 
based upon Kennard et al. (2010). Hydrometrics are statistical measures of the long-term flow 
regime and can include aspects of flow magnitude, duration, timing, frequency and rate of change 
(Kennard et al., 2010). Merrin et al. (2024) details each asset’s ecology and relationship to flow, 
including: 


• habitat dependencies (e.g. floodplain inundation, refuge, recharging of groundwater) 
• life cycle processes (e.g. flow to trigger spawning) 
• migration and movement pathways (e.g. high flows to enable migration into floodplain wetlands 
and along the river) 
• flow to support productivity and food resources (e.g. nutrient plumes into coastal areas). 


Hydrometrics were calculated for each scenario and used to quantify relative change in important 
parts of the flow regime as percentile change relative to the distribution of annual values of 
Scenario AE, calculated over the Assessment period (i.e. 1 September 1890 to 31 August 2022). 
The index of change is calculated as: 

Percentile change=x − scenario medianscenario median × 100 (1) 

Where x is the median of metric i, for the hypothetical scenario, and all values are for individual 
nodes. 

The assets’ important metrics are combined by averaging, with each metric being weighted, 
considering the knowledge base to support it and its significance to the asset’s ecology. The 
percentile change is weighted downstream of nodes by the habitat value of each reach in which 
the asset occurs based upon results of species distribution models, and the change in flow 
dependency is calculated for each node. The species distribution models were developed using a 
combination of Random Forests, Generalised Linear Models (GLMs), and Maxent algorithms (see 
Stratford et al., 2024a). These models were applied to a 2.5 km buffer surrounding the rivers 
within the Southern Gulf catchments to quantify habitat suitability. The change in the flow 
dependencies was weighted by habitat suitability for each asset between the river system model 
nodes of each river reach. As such, river reaches with important asset habitat quality or values are 
weighted higher than marginal habitat. Aggregation of these weighted flow dependency values is 
undertaken to calculate the catchment means of asset–flow dependencies from the individual 
node values (see Ponce Reyes et al., 2024 for more details). 

Hydrometrics have been broadly used in ecohydrology assessments in national and international 
contexts for a range of purposes, including water allocation planning, and in ecohydrology 
research and literature (Leigh and Sheldon, 2008; Marsh et al., 2012; Olden and Poff, 2003). For 
this analysis, the flow dependencies modelling considered reach and catchment-wide changes in 
each asset’s important flow dependencies across the subcatchments in which the assets occur, 
including the near-shore marine zone. The impact of a hypothetical development on water-
dependent ecological assets is inferred and reported here in terms of a habitat-weighted 
percentile change in asset-specific important flow dependencies. 

For interpretation of results, larger values represent greater change in the parts of the flow regime 
that are important for the asset, and qualitative descriptors are provided in Table 7-3. As the 
values are percentile change from the distribution in Scenario AE, the asset’s flow dependency 
values can be referenced against the historical variability. For example, a value of 25 for a metric 
represents a change from the median (50th percentile of the historical distribution) to the 25th 
percentile. Using mean annual flow as an example metric, the value of 25 would represent the 
scenario median now being similar to the driest 25% of years for this metric. 


Table 7-3 Reporting qualitative values for the flow dependencies modelling as rank percentile change of the 
hydrometrics 

Values consider the change in mean hydrometric value against the natural distribution observed in the modelled 
baseline series of 132 years. For more information including metric and habitat weighting see Ponce Reyes et al. 
(2024). For more information see Ponce Reyes et al. (2024). 

PERCENTILE VALUE 

RATING 

IMPLICATION 

>0-2 

Negligible 

The mean for the asset’s metrics under the scenario has negligible change as 
considered against the modelled historical conditions and lies well within the 
normal conditions experienced at the model node. The asset’s hydrometrics 
are within two percentile of the historical Scenario AE mean 

2-5 

Minor 

The change is minor with the mean for the asset’s metrics for the scenario 
between two and five percentile of Scenario AE and the historical distribution 
of the hydrometrics 

5-15 

Moderate 

The change is moderate with the mean for the asset’s metrics under the 
scenario between five and 15 percentile of Scenario AE and the historical 
distribution of the hydrometrics 

15-30 

Major 

The change is major with the mean for the asset’s metrics for the scenario 
between 15 and 30 percentile of Scenario AE and the historical distribution of 
the hydrometrics 

>30 

Extreme 

The change is extreme with the mean for the asset’s metrics under the 
scenario being very different from the modelled historical conditions, with 
and metrics occurring well outside typical conditions at the modelled node. 
The scenario mean is more than 30 percentile from the historical Scenario AE 
mean 



 
In addition to comparing against the historical variability of Scenario AE, benchmarking the level of 
change in asset flow dependencies is achieved by comparing to asset results modelled at the end-
of-system of the Ord River, taking into account the modelled changes in flow associated with the 
development of the Ord River Irrigation Scheme (with and without Top Dam) near the end-of-
system. In addition, three natural periods of low-flow conditions are assessed and plotted 
alongside the hypothetical development and projected climate scenario values. For the Southern 
Gulf catchments, these were the periods with the lowest 30-year flow, lowest 50-year flow and 
lowest 70-year flow across the historical climate (Scenario AE). Additional context is provided by 
calculating the change in asset flow dependency that has been modelled to occur in the Gregory 
and Leichhardt catchments since European settlement (i.e. by comparing key flow dependency 
metrics under Scenario AN and Scenario AE). These are benchmarks, so flow conditions and 
outcomes of change would not necessarily be equivalent to these if development were to occur, 
but they provide a useful comparison of the potential level of change under the scenarios. 

Note that this ecology analysis is broad in scale, and the results include significant uncertainty. 
This uncertainty is due to a range of factors, including, but not limited to, incomplete knowledge, 
variability within and between catchments, and limitations associated with modelling processes 
and data. Furthermore, thresholds, temporal processes, interactions, synergistic effects and 
feedback responses in the ecology of the system may not be adequately captured in the modelling 
process. There is also uncertainty associated with the projected future climates, such as rainfall 
patterns and any additional synergistic and cumulative threatening processes that may emerge 
and interact across scales of space and time, including producing potentially novel outcomes. The 
region that the Southern Gulf catchments occur within is vast and diverse, and the knowledge 


base of species occurrences is limited. More broadly, the understanding of freshwater ecology in 
northern Australia is still developing. 

Provided below is a sample of outcomes for three representative assets for the Southern Gulf 
catchments: sawfishes; swimming, diving and grazing waterbirds; and floodplain wetlands. For 
more details and for results on other assets see Ponce Reyes et al. (2024). 

Sawfishes 

Four species of sawfish inhabit the Gulf of Carpentaria, primarily in inshore marine habitats and 
estuaries. Tropical Australian waters are one of the last strongholds for sawfishes (Phillips et al., 
2011). The two largest species, largetooth or freshwater sawfish (Pristis pristis) and green sawfish 
(P. zijsron) are listed as Critically Endangered on the IUCN Red List of Threatened Species and 
Vulnerable under the Commonwealth EPBC Act. The dwarf sawfish (P. clavata) is listed as Critically 
Endangered (IUCN) and Vulnerable (EPBC Act), while the narrow sawfish (Anoxypristis cuspidata) is 
listed as Critically Endangered (IUCN) and not listed under the EPBC Act. 

Freshwater sawfish juveniles inhabit riverine reaches before moving to coastal and marine 
environments as adults. Juvenile dwarf sawfish have been recorded in upper estuaries and lower 
rivers, while adults are found offshore. Green sawfish are common in estuaries and occasionally in 
riverine habitats. In the Southern Gulf catchments, sawfishes occupy estuarine, freshwater and 
offshore habitats. Estuarine and riverine connectivity is critical for the survival of freshwater 
sawfish, which pup in estuarine and inshore waters (Dulvy et al., 2016; Morgan et al., 2017). 
Sawfishes are vulnerable to human activities and also used as a food source (Naughton et al., 
1986). In Australia, only Indigenous Australians are allowed to capture sawfishes. 

Freshwater sawfish, in particular, are affected by variability in the flow regime despite sustained 
riverine and estuarine connectivity during the wet season. Strong upstream recruitment of 
juveniles to riverine habitats only occurs during the highest flood flows (Lear et al., 2019). The 
higher the volume of flood flows, the greater the sustained body condition of sawfish during the 
subsequent dry season (Lear et al., 2021). 

The key threats to sawfishes are associated with the loss of high-level flood flows to support 
upstream recruitment and with any reduction in low-level dry-season flows that would reduce 
instream connectivity or create barriers among deep-water pools and reduce their persistence or 
water quality during the dry season. The analysis considers change in flow regime and related 
habitat changes but does not consider the loss of potential habitat associated with the creation of 
a dam impoundment or instream structures (see also Yang et al. (2024) for dam impoundments). 

Flow dependencies analysis 

Sawfishes were assessed across a total of 3948 km of river reaches in the Southern Gulf 
catchments and the marine region, with flows from 63 model nodes (Ponce Reyes et al., 2024). 
The locations for modelling sawfishes were selected based on the species distribution models of 
freshwater or largetooth sawfish (Pristis pristis) (see Merrin et al. (2024)). 

Hypothetical water resource development in the Southern Gulf catchments led to varying changes 
in key flow metrics important for sawfish (see details and results for all the scenarios in Ponce 
Reyes et al. (2024)). Hypothetical dam scenarios showed a range of change in key flow metrics 
from negligible (0.6 under Scenario B-DGPCT) to moderate (5.2; Scenario B-D2). Change in key flow 






metrics under water harvesting scenarios was negligible, with values ranging from 0.5 
(Scenario B-WT50P600R30E250) to 1.4 (Scenario B-WT150P200R30E0). Under Scenario Cdry, there was a 
moderate change (6.5) in flow metrics. The variation in flow regime changes across dam, water 
harvesting, and climate scenarios is due to differences in spatial patterns of flow and the 
distribution of important habitat for sawfish (Figure 7-4). 
Water harvesting and changes in important flows for sawfish 
The change in important flows for sawfish under water harvesting varied depending on extraction 
targets, pump-start thresholds, pump rates and annual diversion commencement flow 
requirements (Ponce Reyes et al., 2024). Under a low extraction target of 50 GL 
(Scenario B-WT50P600R30E0), the change in flow was negligible (0.5), and it increased to 0.9 with an 
extraction target of 300 GL (Scenario B-WT300P600R30E0) (Figure 7-5). Raising the pump-start 
threshold from 200 ML/day (Scenario B-WT150P200R30E0) to 600 ML/day (Scenario B-WT150P600R30E0) 
reduced asset dependent flow changes, with values ranging from 1.4 to 0.7. Protecting key parts 
of the flow regime, such as maintaining low flows and limiting extraction volumes, is crucial for 
sawfish ecology. Flow modifications, particularly reduced high flows and shorter peak durations, 
can disrupt species reliant on floodplain inundation and wetland connectivity. Additionally, 
water impoundment or upstream extraction may reduce the depth and persistence of critical 
riverine pools during the dry season. 




Figure 7-3 Riparian vegetation along the Leichhardt River – riparian zones are often more fertile and productive 
than surrounding terrestrial vegetation 

Photo: CSIRO – Nathan Dyer 




For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 7-4 Spatial heatmap of habitat-weighted changes in flow for sawfish, considering the assets important 
locations across the catchment 

Scenarios are: (a) B-WT150P600R30E0, (b) B-WT150P600R30E150, (c) B-WT300P600R30E0, (d) B-D2, (e) CEdry and (f) D-WT150P600R30E0. 
River shading indicates the level of flow change of sawfish important metrics weighted by the habitat value of each 
reach. 




\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\7_Ecology\0_Working\Lynn_ecology\3_Plots\3_SG\Plot1\Plot1C\v6\Sawfish_noBoxPlot_by_MeanChange_orderByLocation_v6b.png
Figure 7-5 Habitat-weighted change in sawfish flow dependencies by scenario across model nodes 

Colour intensity represents the level of change occurring in important flow metrics as percentile change from the 
historical conditions weighted by the importance of each reach for sawfishes. Equivalent colour intensity (i.e. 
corresponding to the asset flow dependency change value) for the Ord River below Lake Kununurra shown bottom 
right. Scenarios are ordered on the left axis by the magnitude of change with the mean across nodes shown on the 
right axis. Horizontal grey bars and number correspond to the mean change across all model node locations. Only the 
30 highest impact nodes are shown (x-axis). Results under Scenario A corresponding to changes in asset flow 
dependency for the lowest 30-year (A lowest 30), 50-year (A lowest 50) and 70-year (A lowest 70) time periods 
provide a reference for the modelled changes under different hypothetical development and projected future climate 
scenarios. AN-AE corresponds to the change in asset flow dependency in the Nicholson and Leichhardt catchments 
that has already occurred since European settlement. 












Dams and changes in important flows for sawfish 
Under the hypothetical dam scenarios, Scenario B-DGPC (without transparent flows) resulted in a 
negligible change in important flow metrics (0.7) when averaged across the 63 sawfish assessment 
nodes. Implementing transparent flows (Scenario B-DGPCT) reduced this to 0.6. Scenario B-DGR 
resulted in a minor flow change (4.9), which was reduced to negligible (1.6) with transparent flows 
(Scenario B-DGRT). Scenario B-D2, involving two dams, showed a moderate change (5.2), which was 
reduced to 3.1 with transparent flows (Scenario B-D2T). As expected, Scenario B-D2 resulted in a 
larger mean change in flow dependency than either of the individual dam scenarios due to the 
combined effects of two dams and the larger portion of the catchment affected. Transparent flows 
consistently mitigated impacts, improving environmental outcomes for sawfish. 
The greatest habitat-weighted changes occurred at node 9121012, with an extreme change (48.2). 
Nodes directly downstream of the dams saw major (16.3) and extreme (45.4) changes, which were 
reduced to moderate levels (11.7 and 12.9) with transparent flows. Dams placed higher in the 
catchment reduced potential impacts, but sawfish remain vulnerable to a combination of factors, 
including changes in flow and connectivity loss (see Ponce Reyes et al. (2024)). 
Climate change and water resource development for important flows for sawfish 
Scenario Cdry resulted in a moderate change (6.5) in important flow metrics for sawfish across the 
63 sawfish assessment nodes, which is higher than the changes seen in scenarios B-DGPC and 
B- WT150P600R30E0 (both negligible; 0.7). However, note that local changes in flows under some 
water resource development scenarios can be considerably higher than the catchment means. 
Combined impacts of climate change and water resource development resulted in moderate 
changes of 7.1 (Scenario D-DGPC) and 7 (Scenario D-WT150P600R30E0), indicating a significant impact 
on sawfish flow dependencies via flow reduction. These changes, especially reductions in wet-
season flood flows and late-dry-season low flows, could reduce neonate recruitment upstream 
and disrupt connectivity to wetlands. Dams further impede access to juvenile habitats (see Yang 
et al. (2024)), while large flood flows are critical for the recruitment, growth and survival of 
largetooth sawfish within riverine freshwater habitats (Lear et al., 2019; Lear et al., 2021). Flow 
modifications, particularly reductions in high flows and shortened peak water levels, can 
negatively affect species relying on floodplain inundation and wetland connectivity (Close et al., 
2014; Hunt et al., 2012; Jellyman et al., 2016; Morgan et al., 2016; Novak et al., 2017). Among 
Australian tropical rivers at similar latitudes, water resource development and a drying climate 
have been modelled to have significant negative impacts on sawfish populations (Plagányi et al., 
2024). Measures to protect important parts of the flow regime can support ecology; for example, 
reducing the extraction target puts limits on the volume of water extracted in any water year, and 
increasing the pump-start threshold protects the low flows that are important for sawfish 
ecology. Flow modifications, particularly the reduction of high flows and shortened duration of 
the peak water levels (upper 25% of flows), can affect species such as the sawfish that rely on 
floodplain inundation and wetland connectivity. Furthermore, the maintenance of depth and 
persistence of important riverine pools during the dry season may be reduced by water 
impoundment or upstream extraction. 














Swimming, diving and grazing waterbirds 
The swimming, diving and grazing waterbirds group comprises species with a relatively high level 
of dependence on semi-open, open and deeper water environments, who commonly swim when 
foraging (including diving, filtering, dabbling, grazing) or when taking refuge. In northern Australia, 
this group comprises 49 species from 11 families, including ducks, geese, swans, grebes, pelicans, 
darters, cormorants, shags, swamphens, gulls, terns, noddies and jacanas (see species list in 
Merrin et al. (2024)). Reduced extent, depth and duration of inundation of waterhole and other 
deep-water environments are likely to reduce habitat availability and food availability for 
swimming, diving and grazing waterbirds. Reduced high-level flows increases competition, and 
predation also increases the risk of disease and parasite spread. Conversely, species in this group 
that nest at water level or just above, such as magpie geese (Anseranas semipalmata), are 
particularly at risk of nests drowning when water depths increase unexpectedly. The analysis 
focuses on flow regime changes and excludes habitat changes associated with a dam creation (see 
also Yang et al. (2024)). 
Flow dependencies analysis 
Swimming, diving and grazing waterbirds were assessed across a total of 3948 km of river reaches 
in the Southern Gulf catchments using flows from 62 model nodes The locations for modelling 
these birds were selected based on species distribution models of the magpie goose (Anseranas 
semipalmata) (see Merrin et al. (2024)). 
Hypothetical water resource development in the Southern Gulf catchments led to varying levels of 
change in key flow metrics important for these waterbirds. Across all 62 analysis nodes, dam 
scenarios showed changes ranging from negligible (0.5; Scenario B-DGPCT) to minor (3.5; Scenario 
B-D2). In contrast, water harvesting scenarios resulted in negligible changes 0.4 to 1.1 for scenarios 
B-WT50P600R30E150 and B-WT150P200R30E0, respectively. Scenario Cdry resulted in a moderate change(5.1) in important flow metrics. The impact associated with these scenarios varied due to spatial 
differences in flow regime changes and the distribution of important habitat for swimming, diving 
and grazing waterbirds (Figure 7-6).
Water harvesting and changes in important flows for swimming, diving and grazing waterbirds 
The hypothetical water harvesting scenarios for swimming, diving and grazing waterbirds resulted 
in a negligible mean change ranging from 0.4 to 1.1 for scenarios B-WT50P600R30E150 and B-
WT150P200R30E0, respectively. Changes in important flows under water harvesting scenarios varied 
depending on extraction targets, pump-start thresholds, pump rates and annual diversion 
commencement flow requirements (Figure 7-6). With a low extraction target of 50 GL (Scenario 
B-WT50P600R30E0), the mean weighted change in flows remained negligible at 0.4. This increased 
slightly to 0.7 with a higher extraction target of 300 GL (Scenario B-WT300P600R30E0). The pump-start 
threshold is important for protecting low flows by preventing pumping when the river is below this 
threshold. With a 150 GL extraction target, increasing the pump-start threshold from 200 ML/day 
(Scenario B-WT150P200R30E0) to 600 ML/day (Scenario B-WT150P600R30E0) reduced the mean change 
from 1.1 to 0.6 (negligible) (Figure 7-6). Measures such as limiting extraction targets and 
increasing the pump-start threshold can help protect the low flows that are important for 
swimming, diving and grazing waterbirds ecology. 
440 | Water resource assessment for the Southern Gulf catchments 


 

\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\7_Ecology\0_Working\Lynn_ecology\3_Plots\3_SG\Plot1\Plot1C\v6\Swimmers..divers..and.grazers_noBoxPlot_by_MeanChange_orderByLocation_v6b.png
Figure 7-6 Habitat-weighted change in swimming, diving and grazing waterbirds flow dependencies by scenario 
across model nodes 

Colour intensity represents the level of change occurring in important flow metrics as percentile change from the 
historical conditions weighted by the importance of each reach for swimming, diving and grazing waterbirds. 
Equivalent colour intensity (i.e. corresponding to the asset flow dependency change value) for the Ord River below 
Lake Kununurra shown bottom right. Scenarios are ordered on the left axis by the magnitude of change with the mean 
across nodes shown on the right axis. Horizontal grey bars and number correspond to the mean change across all 
model node locations. Only the 30 highest impact nodes are shown (x-axis). Results under Scenario A corresponding to 
changes in asset flow dependency for the lowest 30-year (A lowest 30), 50-year (A lowest 50) and 70-year (A lowest 
70) time periods provide a reference for the modelled changes under different hypothetical development and 
projected future climate scenarios. AN-AE corresponds to the change in asset flow dependency in the Nicholson and 
Leichhardt catchments that has already occurred since European settlement. 

 












Dams and changes in important flows for swimming, diving and grazing waterbirds 
Under the dam scenarios, Scenario B-DGPC resulted in a negligible change (0.6) in important flow 
metrics when averaged across the 62 swimming, diving and grazing waterbirds assessment nodes. 
With the implementation of transparent flows in Scenario B-DGPCT, the change was further reduced 
to 0.5 (negligible). Scenario B-DGR, in contrast, resulted in a minor change (3.2), which was reduced 
to negligible (0.8) with the transparent flows under Scenario B-DGRT. Scenario B-D2, which includes 
both the B-DGPC and B-DGR dams, resulted in a larger mean flow change across the catchment 
compared to either single dam scenario. The mean change across the catchment without 
transparent flows was minor (3.5) and this was reduced to negligible (1.7; Scenario B-D2T) with 
transparent flows. The greater change under Scenario B-D2 compared to the single dam scenarios 
is due to the combined effects of the two dams and their larger impact on the catchment. Scenario 
B-D2T (with transparent flow) resulted in a smaller change than scenarios without transparent 
flows, demonstrating the importance of providing flows to support environmental outcomes for 
swimming, diving and grazing waterbirds (Figure 7-6).
Under dam scenarios, node 9121015 showed the greatest habitat-weighted changes in important 
flows for swimming, diving and grazing waterbirds (Figure 7-6) with the change recorded as 
extreme (51.5). Nodes directly downstream of the dams under scenarios B-DGPC and B-DGR resulted 
in moderate (8.7) and major (19.5) changes in important flows, respectively. These changes were 
reduced to moderate (5.1) and minor (3.7), respectively, when modelled with transparent flows. 
This pattern reflects the combined effect of flow changes directly downstream of the dams and 
the benefits of providing flows to support environmental outcomes. 
Climate change and water resource development for important flows for swimming, diving and 
grazing waterbirds 
Scenario Cdry resulted in a moderate change (5.1) in important flow metrics based on the mean 
across the 62 swimming, diving and grazing waterbirds assessment nodes (Figure 7-6). This 
indicates that the dry climate scenario led to a larger mean change than did Scenario B-DGPC and 
B-WT150P600R30E0, both of which showed negligible changes (0.6). However, note that local changes 
in flows can be considerably higher than the catchment means under some water resource 
development scenarios. When considering the impacts of climate change combined with water 
resource development, scenarios D-DGPC and D-WT150P600R30E0 both resulted in moderate changes 
(5.4), which is higher than the impacts of Scenario Cdry or either of scenarios B-D2 and 
B-WT160P200R30 alone. 
Species in the swimming, grazing and diving waterbirds group are sensitive to changes in the 
depth, extent and duration of perennial semi-open and open deeper water environments such as 
wetlands and waterholes (Marchant and Higgins, 1990; McGinness, 2016). They can also be 
sensitive to changes in the type, density or extent of the fringing aquatic or semi-aquatic 
vegetation in and around these habitats. These changes can occur when water is extracted directly 
from these habitats or when the time between connecting flows or rainfall events that fill these 
habitats is extended (Kingsford and Norman, 2002). Climate change as explored through the 
Scenario Cdry and extremes are likely to interact with changes induced by water resource 
development, including inundation of freshwater habitats by seawater, and inundation of nests by 
extreme flood events or seawater intrusion (Nye et al., 2007; Poiani, 2006; Traill et al., 2009a; 
Traill et al., 2009b). The reduced extent, depth and duration of inundation of waterholes and other 
442 | Water resource assessment for the Southern Gulf catchments 
















deep-water environments is likely to reduce their habitat and food availability, increasing 
competition and predation and also increasing risk of disease and parasite spread. Conversely, 
species in this group that nest at water level or just above, such as magpie geese, are particularly 
at risk of nests drowning when water depths increase unexpectedly (Douglas et al., 2005; Poiani, 
2006; Traill et al., 2010; Traill et al., 2009a; Traill et al., 2009b). 
Floodplain wetlands 
For this analysis, floodplain wetlands are defined as freshwater lakes, ponds, swamps and 
floodplains with water that can be permanent, seasonal or intermittent, and can be natural or 
artificial. The Southern Gulf catchments contain 13 nationally significant wetlands listed in the 
Directory of Important Wetlands in Australia, although none are listed under the Ramsar 
Convention (see Merrin et al. (2024)). Wetlands provide permanent, temporary or refugia habitat 
for a range of species, are important for driving both primary and secondary productivity, and 
provide a range of additional ecosystem services (Junk et al., 1989; Mitsch et al., 2015; Nielsen et 
al., 2015; van Dam et al., 2008a; Ward and Stanford, 1995). 
Floodplain wetlands are influenced by the timing, duration, extent and magnitude of floodplain 
inundation, which significantly affect their ecological values, including species diversity, 
productivity and habitat structure (Close et al., 2015; Tockner et al., 2010). In the southern Gulf of 
Carpentaria, during high-level flood flows, floodplain wetlands connect with coastal salt flats as a 
‘shallow lake’ continuum. Freshwater fauna move downstream and brackish-water-tolerant 
estuarine species move from the river channels onto the inundated, productive salt flats to forage 
and reproduce, taking advantage of the food web that depends on the floodwater-stimulated algal 
crusts that invigorate from their dry-season senescence (Burford et al., 2016; Burford et al., 2010). 
The key threats to floodplain wetlands are changes in flood regimes, specifically the timing, 
duration, extent and magnitude of floodplain inundation and the ensuing effect on the habitat 
structure, size and permanence of the wetlands and thus on species diversity and community 
productivity. 
Flow dependencies analysis 
Floodplain wetlands were assessed across a total of 2027 km of river reaches in the Southern Gulf 
catchments with contributing flows from 34 model nodes (see Ponce Reyes et al. (2024)). Key river 
reaches for floodplain wetlands in the Assessment catchments were modelled downstream of 
nodes 9139000, 9130140 and 9130050, which were selected based upon wetland and floodplain 
mapping (see Merrin et al. (2024)). 
Hypothetical water resource development in the Southern Gulf catchments resulted in varying 
changes to key flow metrics affecting floodplain wetlands. The mean weighted change in flow of 
the hypothetical dam scenarios across all 34 floodplain wetlands analysis nodes ranged from 
negligible (0.3; Scenario B-DGPCT) to minor (3.6; Scenario B-D2T). In contrast, water harvesting 
scenarios ranged from negligible (0.6; Scenario B-WT50P600R30E0) to minor (2.3; Scenario 
B-WT300P600R30E0). Scenario Cdry resulted in a moderate change in important flow metrics (12.9) for 
floodplain wetlands. The level of flow regime change associated with dam construction, water 
harvesting and climate scenarios varied due to the differing spatial patterns of flow regime change 
and the distribution of important habitat for floodplain wetlands (Figure 7-7). 




\\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\7_Ecology\0_Working\Lynn_ecology\3_Plots\3_SG\Plot1\Plot1C\v6\Floodplain.wetlands_noBoxPlot_by_MeanChange_orderByLocation_v6b.png
Figure 7-7 Habitat-weighted change in floodplain wetlands flow dependencies by scenario across model nodes 

Colour intensity represents the level of change occurring in important flow metrics as percentile change from the 
historical conditions weighted by the importance of each reach for floodplain wetlands. Equivalent colour intensity 
(i.e. corresponding to the asset flow dependency change value) for the Ord River below Lake Kununurra shown 
bottom right. Scenarios are ordered on the left axis by the magnitude of change with the mean across nodes shown 
on the right axis. Horizontal grey bars and number correspond to the mean change across all model node locations. 
Only the 30 highest impact nodes are shown (x-axis). Results under Scenario A corresponding to changes in asset flow 
dependency for the lowest 30-year, 50-year and 70-year time periods provide a reference for the modelled changes 
under different hypothetical development and projected future climate scenarios. AN-AE corresponds to the change 
in asset flow dependency in the Nicholson and Leichhardt catchments that has already occurred since European 
settlement. 
















Water harvesting and changes in important flows for floodplain wetlands 
The hypothetical water harvesting scenarios resulted in a mean change across floodplain wetland 
assessment nodes from negligible (0.6; Scenario B-WT50P600R30E0) to minor (2.3; Scenario 
B-WT300P600R30E0). The changes varied depending on extraction targets, pump-start thresholds,
pump rates, and annual diversion commencement flow requirements (Figure 7-7). For a lowextraction target of 50 GL (Scenario B-WT50P600R30E0), the flow change was negligible (0.6), and thisincreased to minor (2.3) with a higher extraction target of 300 GL (Scenario B-WT300P600R30E0). Thepump-start threshold is important for protecting low flows by preventing pumping when the riveris below this threshold. With a 150 GL extraction target, raising the pump-start threshold from200 ML/day (Scenario B-WT150P200R30E0) to 600 ML/day for (Scenario B-WT150P600R30E0) slightlyreduced the flow change from 1.6 to 1.5 (Figure 7-7). Measures to protect important parts of theflow regime can support ecology; for example, reducing the extraction target puts limits on thevolume of water extracted in any water year, and increasing the pump-start threshold protectsthe low flows.
Dams and changes in important flows for floodplain wetlands 
Under the dam scenarios, when averaged across the 34 floodplain wetlands assessment nodes, 
Scenario B-DGPC (without transparent flows) resulted in a negligible change (0.3) in flow metrics for 
floodplain wetlands. This change remained the same with transparent flows (Scenario B-DGPCT). 
Scenario B-DGR resulted in a minor change (3.2), which slightly increased to 3.3 with transparent 
flows under Scenario B-DGRT. In Scenario B-D2, which includes both dams, a minor (3.4) mean 
change occurred, and this increased to 3.6 with transparent flows. Scenario B-D2 resulted in a 
larger mean flow change across the catchment than either of the single dam scenarios. This 
increase was due to the combined effects on flows downstream and the larger portion of the 
catchment affected. 
Habitat-weighted flow changes were most significant at node 9121050 and directly downstream 
(Figure 7-7), with a major change (26.5; Scenario B-DGR). This was reduced to 22.5 (major) with 
transparent flows (Scenario B-DGRT). This pattern reflects the combined effect of flow changes 
directly downstream of the dams and the benefits of providing flows to support environmental 
outcomes. Dams can have a significant impact on floodplain wetlands, as they capture runoff 
from rainfall events that would otherwise spill onto floodplains during larger events and facilitate 
the connection of the wetlands to the main river channel. The reduction in flood magnitude due 
to dams can change the connectivity between the river channel and the floodplain wetlands, 
significantly affecting the size of the inundated area. A loss of connectivity between the river 
channel and the floodplain wetland may also occur. This disconnection can alter the frequency 
and duration of wetland inundation, potentially leading to changes in the structure, function and 
biodiversity of these wetland habitats (Poff and Zimmerman, 2010; Richter et al., 1996). 
Climate change and water resource development for important flows for floodplain wetlands 
Scenario Cdry resulted in a moderate change (12.9) in important flow metrics for floodplain 
wetlands based on the mean across the 34 floodplain wetland assessment nodes (Figure 7-7). This 
indicates that the dry climate scenario led to a larger mean change across all catchment nodes 
than scenarios B-DGPC (negligible; 0.3) and B-WT150P600R30E0 (negligible; 1.5). However, it is 
important to note that local changes in flows under some water resource development scenarios 
can be considerably higher than the catchment means. Considering the combined impacts on 
flow associated with climate change and water resource development, scenarios D-DGPC and 












D-WT150P600R30E0 resulted in moderate (13.2 and 13.9, respectively) changes when weighted across 
all floodplain wetland assessment nodes. This shows that the changes of scenarios D-DGPC or 
DdryWT150P600R30E0 were higher than those of Scenario Cdry or either of scenarios B-D2 and 
B-WT160P200R30 alone.
7.3.5 Management of impacts on ecology 
The magnitude and spatial extent of ecological impacts arising from water resource development 
are highly dependent on the type and location of development, the extraction volume and how 
the type of changes in the flow regime affect different aspects of flow ecology. Mitigation 
measures seek to protect key parts of the flow regime and can be important for sustaining ecology 
under water resource development. This section explores the effectiveness of different mitigation 
measures, including providing transparent flows for dams, different rules for water harvesting and 
different overall targets for water extraction. 
Instream dam development 
Two potential locations for instream dams (Gregory River and Gunpowder Creek) were selected 
for modelling and analysis (Yang et al., 2024) and simulated following the hydrology modelling 
approach outlined in Gibbs et al. (2024b). Their locations are shown in Figure 7-2. The objective of 
this analysis is to test the effect of different dam locations and configurations on changes to 
streamflow to understand the effect on downstream ecology. Dams are modelled individually (i.e. 
scenarios B-DGR and B-DGPC), as well as both together (Scenario B-D2) to better understand 
cumulative impacts and to have variants with and without the mitigation measure of providing 
transparent flows (see Ponce Reyes et al. (2024) for definitions). Instream dams create a range of 
impacts on streamflow associated with the capture and extraction of water, affecting the timing 
and magnitude of downstream flows. The change of downstream flow associated with instream 
dams is explored here across broad asset groups, and results are shown as the mean of asset 
values. Impacts associated with loss of connectivity due to the dam wall and loss of habitat 
associated with the dam inundation extent are discussed in Yang et al. (2024). The dam scenarios 
and the resulting ecology flow dependencies are discussed in more detail for each asset in Ponce 
Reyes et al. (2024). 
Assessment of the individual dams found varying levels of effect on ecology flow dependencies 
(Table 7-4). Scenario B-DGPC resulted in no asset group having changes in important flow 
dependencies greater than negligible averaged across their assessment nodes, although local 
impacts on flows were often higher. However, Scenario B-DGR resulted in major change for the 
‘other species’ group including the turtles and prawn species. The dams vary in size, inflows and 
capture volumes, and the location of the dam in the catchment also influences outcomes, 
particularly in the freshwater reaches. Impacts on flow directly downstream of modelled dams can 
often be high and may cause extreme changes in ecological flow dependencies. Areas further 
downstream have contributions from unimpacted tributaries, and for the marine region, from 
flows from other catchments that help support ecological outcomes of flow regimes. Dams further 
up the catchment may, however, affect a larger proportion of streams and river reaches in terms 
of flow regime change but may have lower impacts in terms of connectivity. The Southern Gulf 
catchments, in particular, are complex and braided, and they have many tributaries that may be 
unimpacted within the freshwater sections of the catchment. Effects on important flows are not 
446 | Water resource assessment for the Southern Gulf catchments 


equivalent across assets, and large local impacts may lead to changes in ecology across other parts 
of the catchment due to the connected nature of ecological systems. 

The cumulative change in flow dependencies associated with two dams (Scenario B-D2) are greater 
than those of individual dams (Table 7-4). However, the largest contribution of change to Scenario 
B-D2 originates from B-DGR. Cumulative change in flows on ecology may be associated with acombination of a larger portion of the catchments being affected by changes in flows and residualflows being lower due to the overall greater level of water use and losses from dams (Table 7-4).

Table 7-4 Scenarios of different hypothetical instream dam locations showing mean changes of ecology flows for 
groups of assets across each asset’s respective catchment assessment nodes 

Higher values represent greater change in flows important to the assets of each group. Values are asset means across 
their respective catchment assessment nodes (see Appendix A in Ponce Reyes et al. (2024)). Some assets are 
considered in multiple groups, where the mean across the nodes is used. Asset means include values from all nodes 
that the asset is assessed in, including in reaches that may not be affected by flow regime change. 

SCENARIO 

DESCRIPTION 

ALL ASSET 
MEAN 

FISH 

WATERBIRDS 

OTHER 
SPECIES 

HABITATS 

FRESHWATER 
ASSETS 

MARINE 

ASSETS 

B-DGPC 

Gunpowder Creek 
dam 

0.8 

0.4 

0.8 

0.1 

0.5 

0.8 

0.2 

B-DGPCT 

Gunpowder Creek 
dam with 
transparent flows 

0.7 

0.3 

0.7 

0.1 

0.5 

0.7 

0.2 

B-DGR

Gregory River dam 

4.1 

8.9 

4.0 

18.2 

6.4 

4.4 

12.7 

B-DGRT

Gregory River dam 
with transparent 
flows 

1.5 

1.8 

1.7 

3.8 

2.8 

1.7 

3 

B-D2

Both B-DGPC and B-
DGR

4.5 

9.1 

4.4 

18.3 

6.7 

4.7 

12.8 

B-D2T

Both B-DGPC and B-
DGR with 
transparent flows 

2.7 

5.5 

2.7 

12.7 

4.1 

2.9 

8.4 



Measures to mitigate the flow-related impacts of large instream dams, such as transparent flows 
(inflows let to pass the dam wall for environmental purposes), resulted in lower change to 
ecological flow dependencies broadly across all assets compared to instream dams without these 
measures (Table 7-4). Particularly strong benefits are shown in the reduced change to important 
flow dependencies resulting from transparent flows for members of the fish and waterbird groups 
(see Ponce Reyes et al. (2024) for groupings and more detail). Instream dams capture inflows and 
change downstream flow regimes. Transparent flows are a type of environmental flow provided as 
releases from dams that mimic or maintain some aspects of natural flows. Staged offtakes to 
maintain natural water temperatures are required. However, providing transparent flows from a 
dam it lowers the volume of water in storage and thereby increases the capture of early flood 
events in the following year. This might also result in the lowering of flood peaks, resulting in 
smaller inundation events during periods of floods affecting assets such as surface-water-
dependent vegetation (see Ponce Reyes et al. (2024)). Modelling transparent flows uses inflow 
thresholds on dams and was designed primarily to preserve lower flows during periods of natural 


inflow. Inflow thresholds used in the transparent flows analysis were similar to the commence-to-
pump thresholds used in water harvest scenarios, facilitating comparison. Transparent flow 
scenarios are provided across both individual dams and under Scenario B-D2 (Gibbs et al., 2024b). 

Water harvesting 

For water harvesting scenarios, several measures can mitigate the impacts of flow-related changes 
from extraction. These include limiting system targets to reduce extraction across the catchment, 
implementing a pump-start threshold to restrict pumping during low river flows, setting an annual 
diversion commencement flow requirement to allow a volume of water to pass through the 
system before pumping, and limiting the pump rate for extraction (see Ponce Reyes et al. (2024) 
and Gibbs et al. (2024b) for more details). These measures improve environmental outcomes 
compared to scenarios without them. 

Reducing system targets decreases the changes in flows across asset groups, while larger 
extraction volumes lead to moderate increases in flow dependencies across the catchment’s 
ecological assets. Groups like turtles, prawns and other species and the marine assets (Table 7-2), 
experience greater changes at higher system targets of 400 to 500 GL/year (Figure 7-9) (see Ponce 
Reyes et al. (2024) for details on individual assets). Providing minimum flow thresholds or annual 
diversion commencement requirements can help mitigate these changes. An annual diversion 
commencement flow requirement of 250 GL improves ecological flows across asset groups with 
smaller requirements proportionally reducing flow changes (see Ponce Reyes et al. (2024)). The 
largest benefits for smaller irrigation targets are often seen with an initial 100 GL requirement, as 
this delays the start of pumping, retaining early wet-season flows and shortening the water 
harvest period (Gibbs et al., 2024b). 

Increasing the pump-start threshold to 1000 ML/day significantly reduces changes in flow 
dependencies across several asset groups, particularly for fish, sharks, rays and freshwater-
dependent habitats (Table 7-2) (see Ponce Reyes et al. (2024) for details on individual assets). 
Compared to lower thresholds of 200 or 400 ML/day, the improvements are particularly notable 
beyond 600 ML/day, where the impacts on freshwater-dependent habitats and marine 
environments are reduced (Figure 7-9) (see Ponce Reyes et al. (2024) for more details). Higher 
pump-start thresholds appear most effective when system targets are limited to about 
200 GL/year and when annual diversion commencement requirements are low or absent, as 
substantial flows may have already passed through the system before the pump threshold is 
activated (see Ponce Reyes et al. (2024) for more details). This indicates that optimising the pump-
start threshold is crucial for reducing the strain on ecosystems, particularly during periods of low 
flow. 

Varying levels of end-of-system (EOS) flow requirements also affect different ecological assets in 
relation to system targets. For fish, sharks and rays, increasing the EOS requirement from zero to 
250 GL/day results in minimal changes in flow dependencies, particularly at lower system targets 
(~100 GL/year). However, other groups, such as turtles, prawns and other species, experience 
significant impacts at lower EOS requirements (below 50 GL/day). As the EOS requirement 
increases, these impacts are mitigated, especially at higher system targets. Flow-dependent 
habitats and marine environments are also sensitive to lower EOS requirements, with notable 
reductions in ecological change when the EOS requirement reaches 150 to 250 GL/day. Overall, 
impacts are more evenly distributed across EOS requirements with the least change occurring 


when EOS requirements are higher and system targets are kept below 200 GL/year. This suggests 
that increasing EOS flow requirements provides substantial ecological benefits, particularly for 
groups sensitive to flow changes, such as turtles, prawns and flow-dependent habitats (see Ponce 
Reyes et al. (2024) for more details). 

Finally, limiting pump capacity helps reduce changes in flow dependencies during water 
harvesting. Slower pump rates and minimum thresholds restrict water extraction during the wet 
season. Additionally, limiting pump capacity at higher extraction volumes further reduces the total 
volume extracted and lessens ecological impacts (Gibbs et al., 2024b). 

 


Figure 7-8 Lake Moondarra near Mount Isa is used for urban water supply and is a popular water and recreational 
reserve 

Photo: CSIRO – Nathan Dyer 




For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 7-9 Mean change associated with each asset’s important metrics across water harvesting increments of 
system target and pump-start threshold with no annual diversion commencement flow requirement and pump rate 
of 30 days 

Colour intensity represents the mean level of change in important flow dependencies with the scenario given the 
habitat importance of each node for each asset. 




7.4 Biosecurity considerations 

7.4.1 Introduction 

Biosecurity is the prevention and management of pests, weeds and diseases, both terrestrial and 
aquatic, to limit the risk of detrimental economic, environmental, social and/or cultural impacts. 
‘Pests’ is a broad term encompassing pest insects, other invertebrates (e.g. nematodes, mites, 
molluscs) and vertebrates (e.g. mammals, birds, fish). Weeds broadly include invasive plants and 
algae. Diseases are caused by pathogens or parasites such as bacteria, fungi and viruses. 

Any development of the water resources within the catchments of the Southern Gulf for plant 
industries or aquaculture must take account of biosecurity risks that may threaten production or 
markets. Development in the study area may also pose broader biosecurity risks to other 
industries, the environment or communities and these risks must be prevented and/or managed. 
The catchments of the Southern Gulf extend across Queensland and the NT, so the following 
sections consider biosecurity policies and regulations for both jurisdictions. 

Biosecurity practices to protect the Southern Gulf catchments occur at a range of scales. At the 
national level, the Australian Government imposes quarantine measures to regulate the 
biosecurity risks associated with entry of goods, materials, plants, animals and people into 
Australia. The Queensland and NT governments also have biosecurity legislation to limit the entry 
of new pests, weeds and diseases into their jurisdictions, and to require the control of certain 
species that are already established. There can also be requirements at the regional level, such as 
participating in weed management programs (NT Government, 2021; SGNRM and NWQROC, 
2022). At the local scale, individual properties ideally follow routine biosecurity protocols, and 
work with other similar enterprises in implementing industry-wide biosecurity measures. 

While the Southern Gulf catchments are relatively isolated compared with other regions of 
Australia, they still have physical connections to the neighbouring regions in Queensland and the 
NT, across northern Australia more broadly, with the rest of the country and with neighbouring 
countries such as Indonesia. Examples of such connections are the sharing of specialist cropping 
machinery between agricultural regions, transport of crop products, tourist visits into remote 
areas, international trade and tourism, mining exploration, shifting cattle between pastoral 
properties, army training exercises and movements between Indigenous communities. These 
connections can be pathways for entry of new pests, weeds or diseases. 

This section introduces the impacts, spread and management of pests, weeds and diseases of 
irrigated cropping and aquaculture, as well as invasive species that pose a risk to the Southern Gulf 
catchments. Given the focus on water-intensive primary industries, biosecurity for terrestrial 
livestock industries is not included. 

Impacts of pests, weeds and diseases 

In primary industries, pests, weeds and diseases can cause economic losses by reducing crop yield 
and product quality, interfering with farm operations and, loss of market access plus the costs of 
control measures. The national economic impact of established weeds and vertebrate pests on 
Australian agriculture has been estimated at over $5.3 billion/year (Hafi et al., 2023). Insect pests 
are also a substantial economic burden nationally (Bradshaw et al., 2021). 


The environmental impacts of pests, weeds and diseases, collectively termed ‘invasive species’, 
include loss of native plants and animals (from competition, predation and infection), degradation 
of habitats and disruption of ecosystem processes (e.g. changed fire or moisture regimes). Invasive 
species are the greatest threat to Australia’s threatened flora and fauna (Ward et al., 2021). For 
example, myrtle rust (Austropuccinia psidii) has potential to cause the extinction of some rare, 
native myrtaceous shrubs and trees (Makinson et al., 2020). 

Social impacts of pests, weeds and diseases include loss of public amenity and access to outdoor 
areas, damage to infrastructure and public safety risks. Cultural impacts include a loss of 
traditional foods, impaired access for hunting and damage to cultural sites. For example, Gamba 
grass (Andropogon gayanus) is an African grass originally introduced for pasture in the NT and is 
now a Weed of National Significance (WoNS). WoNS are nationally agreed weed priorities that 
have been a focus for prevention and improved management (Hennecke, 2012; CISS, 2021). 
Gamba grass forms tall, dense stands that burn intensely, posing significant risks to public safety, 
community and primary industries infrastructure, Indigenous heritage sites, native ecosystems and 
grazing lands (Setterfield et al., 2013). 

Pathways of movement 

Pests, weeds and diseases spread via movement of adults and juveniles (e.g. vertebrate pests), 
with movement of their hosts (e.g. infected aquaculture broodstock or nursery stock for planting, 
harvested produce infested with insect larvae) and by movement of propagules (e.g. fungal 
spores, insect eggs, weed seeds, viral particles). Such movements provide many pathways by 
which pests, weeds and diseases could be introduced to the Southern Gulf catchments, potentially 
causing new outbreaks. Just as importantly, there is also the potential for pests, weeds and 
diseases from the Southern Gulf catchments to spread to other areas in Queensland and the NT, 
and elsewhere in Australia. 

Human-mediated spread 

Human activities are the key means of long-distance and local movement. Pests and propagules, 
including those within transported soil, can ‘hitchhike’ on or in vehicles, construction and farm 
machinery, shipping containers and other equipment brought into a region. The ease of 
movement on vehicles and machinery means that the road network (including access roads to 
camping areas, railways, pipelines and powerlines) can be a frequent source of new infestations. 

Propagules may contaminate livestock, seed or nursery stock for establishing crops, hay, road base 
and landscaping supplies (including turf and ornamental plants). Weed infestations can also arise 
from invasive garden, crop and pasture plants. Aquatic pests and diseases may become 
established due to deliberate species release into the environment for fishing, inadvertent 
transport on fishing equipment or vessels, or dumping of aquarium contents. 

Incursions of new pests, weeds and diseases from overseas are most likely to occur through 
contamination of imported goods or containers, or be carried by people (e.g. propagules on shoes 
or clothing, smuggling of seed or fruit). 


Natural spread 

Natural dispersal via wind, water and wild animals usually occurs over short distances. Extreme 
weather events such as floods and cyclones can disperse pests, weeds and diseases over long 
distances in addition to causing major environmental disturbances that increase the likelihood of 
invasive species becoming established. Ebner et al. (2020) flagged the floodplain lowlands of the 
Gulf of Carpentaria as a high risk for pest fish movement due to a natural and relatively regular 
connectivity of adjacent catchments during periods of torrential rain. Furthermore, irrigation 
infrastructure such as dams, pipelines and channels may facilitate distant spread via water 
movements of some aquatic pests, weeds and diseases, within and across catchments. Some 
animal pests, such as locusts and fall armyworm (Spodoptera frugiperda), naturally migrate long 
distances. 

Northern Australia is close to the southern coasts of Indonesia, Timor-Leste and Papua New 
Guinea (PNG). These neighbouring countries have a range of serious plant pests and diseases that 
are not present in Australia, including exotic fruit flies and citrus canker (Xanthomonas citri subsp. 
citri). The likelihood of their arrival by long-distance wind dispersal is uncertain, particularly with 
regards to novel atmospheric conditions and extreme weather events occurring under climate 
change. However, their economic consequences in Australia would be severe were they to 
establish in Australia. Thus, ongoing biosecurity vigilance in northern Australia through 
government, industry and community surveillance is vital (DAFF, 2024a; PHA, 2021). 

7.4.2 Pest, weed and disease threats to the Southern Gulf catchments 

The Southern Gulf catchments principally face biosecurity risks from pests, weeds and diseases 
already present in the catchment and those that occur in neighbouring regions of northern 
Australia. However, pests, weeds and diseases could also come from other parts of Australia with 
similar climates and/or production systems, or from overseas. 

Examples of pests, weeds and diseases that pose a risk to the Southern Gulf catchments are 
highlighted in the following sections. Whether any one of these would have a significant impact at 
the property level depends on the local environment, land use and agricultural or aquatic 
enterprise. However, there is a legal requirement to prevent and manage any pest, weed or 
disease that is formally ‘declared’ under jurisdictional biosecurity legislation, regardless of its local 
impact. Furthermore, in Queensland there is a general biosecurity obligation (GBO) under the 
Biosecurity Act 2014 (Qld) that all persons must take all reasonable and practical steps under their 
control to not pose a biosecurity risk to others, in all locations (e.g. workplace, home, visiting). This 
applies regardless of whether a particular pest, weed or disease has been declared as prohibited 
or restricted matter in Queensland. 

Plant industries 

The priority pests and diseases for cropping in the Southern Gulf catchments depend on what is 
grown. Table 7-5 gives examples of high-impact pest and disease threats to particular crops, and 
their current distribution and legal status under the Queensland Biosecurity Act and the NT Plant 
Health Act 2008 (DITT, 2023; Queensland Government, 2022). Information on pests and diseases 
of plant industries is given on the Queensland and NT governments’ websites (Queensland 
Government, 2022; NT Government, 2024a). Plant Health Australia is a centralised resource on 


exotic (i.e. overseas) biosecurity risks to Australia’s plant industries. Research and development 
corporations, including the Grains Research and Development Corporation, the Cotton Research 
and Development Corporation, AgriFutures Australia and Hort Innovation also provide extension 
publications on identifying and managing biosecurity threats. 

Many pests and diseases have a high host specificity to a particular crop, but there are also 
generalists that can use many crops as hosts. Local native species can also pose risks of impacts. 
For example, naturally occurring pathogens of various native wild rices may infect cultivated rice 
(Chapman et al., 2020) or native animals may graze on crops. 

Irrigation brings the potential for year-round cropping, which can provide a ‘green bridge’ in the 
dry season to enable pests or diseases, including native insects and diseases, to persist and 
increase locally, and to potentially spread to other areas. 

A significant new generalist pest of cropping is fall armyworm, which has become widely 
established across northern Australia since a national incursion was detected in 2020. It is likely to 
be present year round in the Southern Gulf catchments, with a lower incidence in the dry season 
(PHA, 2020). Fall armyworm caterpillars favour C4 grass crops (e.g. maize, sorghum, rice) and 
pastures but may also feed on broadleaved crops such as soybean, melon, green bean and cotton. 
Young crops are most at risk of severe damage and can require immediate insecticide treatment if 
invaded at levels above the damage threshold. 

Cucumber green mottle mosaic virus (CGMMV) infects a wide range of cucurbit crops, including 
various melons, cucumber, pumpkin and squash, and can also be hosted by a range of 
broadleaved crop weeds. It causes plant stunting and fruit discolouration, malformation and 
rotting. CGMMV is present on a few farms in Queensland but is more widespread in the NT. It has 
also been found interstate. Its presence on-farm can make access to interstate markets more 
difficult as many jurisdictions have imposed quarantine requirements. Infected plants cannot be 
treated, so preventive farm biosecurity measures are vital (NT Government, 2024a; Queensland 
Government, 2019). 

Types of weed threats differ between plant industries according to production methods. For 
example, annual grain and cotton crops tend to have annual weeds (grasses and herbs) and 
herbaceous perennials which persist and spread vegetatively via underground rhizomes. Perennial 
horticulture disturbs the soil less, so typically has more perennial grasses and perennial 
broadleaved weeds. The highest priority weeds in cropping tend to be those that are most difficult 
to control, such as herbicide-resistant biotypes or species that are otherwise tolerant to routinely 
used herbicides. For example, some annual grasses that invade cotton crops have developed 
resistance to certain herbicides, including barnyard grass (Echinochloa spp.) and feathertop 
Rhodes grass (Chloris virgata) (CRDC, 2023). 

Various native vertebrates may consume grain and horticultural crops that are becoming 
established and damage tree crops. These vertebrate pests include birds (waterfowl, cockatoos), 
macropods (kangaroos, wallabies) and rodents. Large flocks of magpie geese (Anseranas 
semipalmata) can be particularly destructive, trampling, grazing and uprooting plants and 
consuming fruit (Clancy, 2020). 


Table 7-5 Examples of significant pest and disease threats to plant industries in the Southern Gulf catchments 

Links to further information are current as of March 2024 

BIOSECURITY THREAT AND LEGAL STATUS (NT/QLD) 

For NT: Plant Health Act 2008 – D = declared; nd = not 
declared 

For Queensland: Biosecurity Act 2014 – 

P = prohibited matter; R = restricted matter; FNP = far 
northern pest; GBO = general biosecurity obligation 

CURRENT STATUS 

CROPS AT RISK 

INVERTEBRATE PESTS 

Asian citrus psyllid Diaphorina citri nd/P, GBO 

Incursion risk from overseas (including Indonesia 
and PNG) 

Citrus 

Cluster caterpillar Spodoptera litura nd/GBO 

Widespread in northern Australia 

Cotton, pulses, brassicas 

Fall armyworm Spodoptera frugiperda nd/GBO 

Widely established across northern Australia 
following first detection in 2020 

Grasses (cereal and 
fodder), cotton, soybean, 
melon, green beans 

Fruit flies, various species including: 

Mediterranean fruit fly Ceratitis capitata D/P, GBO 

Melon fruit fly Bactrocera cucurbitae D/P, GBO 

Oriental fruit fly Bactrocera dorsalis D/P, GBO 

New Guinea fruit fly Bactrocera trivialis D/P, GBO 

Queensland fruit fly Bactrocera tryoni D/GBO 

Mediterranean fruit fly established in WA. 
Queensland fruit fly endemic in the NT and 
Queensland. Melon, oriental, New Guinea and 
other exotic fruit fly incursion risks from overseas 
(incl. Indonesia, PNG) and the Torres Strait 

Fruit and fruiting 
vegetable crops 

Bollworms Helicoverpa spp., Pectinophora spp. nd/GBO 

Widespread in northern Australia 

Cotton, pulses, brassica, 
sunflower, forage 
sorghum, grain sorghum, 
maize 

Guava root-knot nematode Meloidogyne enterolobii D/GBO 

Recent detections in the NT (Darwin region) and 
Queensland 

Cucurbits, solanaceous 
crops, sweet potato, 
cotton, guava, ginger 

Leaf miners: 

American serpentine leaf miner Liriomyza trifolii nd/GBO 

Serpentine leaf miner Liriomyza huidobrensis nd/GBO 

Vegetable leaf miner Liriomyza sativae D/FNP, GBO 

Serpentine and American serpentine leaf miners 
are recent incursions now present in various 
locations across Australia. Vegetable leaf miner is 
present and under control in the far northern 
biosecurity zone, Queensland 

Vegetables, cotton 

Mango pulp weevil Sternochetus frigidus D/GBO 

Incursion risk from overseas (including Indonesia) 

Mango 

Mango shoot looper Perixera illepidaria nd/GBO 

Recent incursion in Queensland and the NT 

Mango, lychee 

Melon thrips Thrips palmi D/GBO 

Limited presence in the NT north of Alligator River 
township and in Queensland 

Vegetables 

Spur throated locust Austracris guttulosa nd/GBO 

Native to northern Australia 

Grasses (cereal and 
fodder), sunflowers, 
soybeans, cotton 

DISEASES 

Alternaria leaf blight Alternaria alternata nd/GBO 

Present in northern Australia 

Cotton 

Banana freckle Phyllosticta cavendishii D/P, GBO 

Under eradication in the NT 

Banana 

Brown spot Cochliobolus miyabeanus nd/GBO 

Endemic on wild rices in northern Australia 

Rice 

Citrus canker Xanthomonas citri subsp. citri D/P, GBO 

Eradicated from the NT and Queensland. Incursion 
risk from overseas (incl. Indonesia, Timor-Leste 
and PNG) 

Citrus 

Cucumber green mottle mosaic virus (CGMMV) nd/R, GBO 

Present in certain areas in the NT, Queensland and 
other states 

Cucurbits 

Fusarium wilt Fusarium oxysporum f. sp. vasinfectum 
D/GBO 

Not present in the NT 

Cotton 

Huanglongbing Candidatus Liberibacter asiaticus D/GBO 

Incursion risk from overseas (including Indonesia, 
Timor-Leste and PNG) 

Citrus 

Panama disease tropical race 4 (Panama TR4) 

Fusarium oxysporum f. sp. cubense D/GBO 

Established throughout the NT. Limited 
distribution in Queensland and mandatory code of 
practice for its management and control 

Banana 

Rice blast Pyricularia oryzae nd/GBO 

Endemic on wild rices in northern Australia 

Rice 




Aquaculture 

A wide range of diseases and parasites are of concern to Australian aquaculture (DAWE, 2020a), 
including those not known to be in Australia, those now established (i.e. endemic) in Australia and 
those native to Australian ecosystems. 

Barramundi farmers need to consider preventing and managing the biosecurity risks of a range of 
endemic parasites and viral, bacterial and fungal pathogens that naturally occur in northern 
Australia (Irvin et al., 2018). In addition, national quarantine measures are vital to prevent exotic 
disease risks for barramundi from entering Australia (Landos et al., 2019). 

Prawn aquaculture in northern Australia is most at risk from white spot syndrome virus (WSSV), 
for which there have been national incursion responses at prawn farms and hatcheries in south-
east Queensland and northern NSW. However, there are also many other exotic crustacean 
diseases (DAWE, 2020a). Endemic viruses (and endemic genotypes of viruses also found overseas) 
that occur naturally in Australian waters can also trigger mortalities or reduce productivity (Irvin et 
al., 2018). 

Invasive species 

Invasive species, whether pest, weed or disease, are commonly characterised as occurring across 
multiple land uses in a landscape. Their impacts will vary between land uses, but their coordinated 
control requires action across all tenures. 

Weeds 

Table 7-6 lists regional weed priorities in the Southern Gulf catchments and their legal status 
under the NT Weed Management Act 2001 and the Queensland Biosecurity Act 2014 (NT 
Government, 2021; SGNRM and NWQROC, 2022). Of those listed, parthenium weed (Parthenium 
hysterophorus), Bathurst burr (Xanthium spinosum) and Noogoora burr (X. occidentale) are direct 
competitors and potential contaminants in dryland and irrigated crops. Parthenium weed also 
poses a health risk to animals and people as a severe allergen. Many species in Table 7-6 are 
WoNS. 

Aquatic weeds can hamper the efficient function of irrigation infrastructure and also cause severe 
ecological impacts through dense infestations in waterways and wetlands. More-constant water 
flows from within-stream reservoirs can also change riparian conditions from seasonally 
ephemeral to perennial, predisposing native vegetation to invasion by weeds that thrive in moist 
environments. 

Terrestrial vertebrate pests 

Various large feral herbivores are present in the Southern Gulf catchments, including buffalo 
(Bubalus bubalis), horses (Equus caballus), donkeys (E. asinus) and pigs (Sus scrofa). They can 
directly affect agricultural production through grazing impacts, severe soil erosion and damaged 
infrastructure such as fencing and irrigation channels. Feral animal damage to habitats is a key 
disturbance mechanism that facilitates weed invasion, particularly in riparian and wetland areas. 
Feral pigs in particular are a major threat to irrigated cropping. Their daily water requirement 
means that they concentrate during the dry season around watercourses and man-made water 
supplies (Bengsen et al., 2014). 


Cane toads (Rhinella marina) are already established in the Southern Gulf catchments (Kearney et 
al., 2008), but would likely become more abundant around irrigation developments where they 
could access year-round moisture (Bengsen et al., 2014). 

Aquatic pests 

Freshwater aquatic pests such as non-native fish, molluscs and crustaceans can affect biodiversity 
and ecosystem functioning. While these pests may not directly affect irrigated cropping, the 
associated infrastructure required (e.g. dams, channels, drains) brings increased risk of deliberate 
release by people for recreational fishing or the disposal of aquarium contents. This infrastructure 
can also provide enhanced habitat and pathways for the persistence and dispersal of aquatic pests 
and weeds in the catchment (Ebner et al., 2020). 

Table 7-6 Regional weed priorities and their management actions in Southern Gulf catchments 

WEED AND LEGAL STATUS 

WoNS = Weed of National Significance 

For NT: Weed Management Act 2001 – 

D = declared; † = has a statutory management plan under the 
Act 

For Queensland: Biosecurity Act 2014 – 

P = prohibited matter; R = restricted matter; GBO = only the 
general biosecurity obligation applies 

REGIONAL ACTION 

HABITATS AT RISK 

NT 

QLD 

AQUATIC 

(e.g. river, 
wetland, dam) 

WETTER AREAS 

(e.g. riparian, 
floodplain, drain) 

DRIER AREAS 

(e.g. grassland, 
woodland) 

AQUATIC/SEMI-AQUATIC HERB 

Cabomba Cabomba caroliniana WoNS D/R 

P 

P 

✓ 

✓ 



Limnocharis Limnocharis flava D/R 

P 

P 

✓ 

✓ 



Sagittaria Sagittaria platyphylla WoNS D/R 

P 

P 

✓ 

✓ 



Salvinia Salvinia molesta WoNS D/R 

P 

C ‡ 

✓ 

✓ 



Water mimosa Neptunia plena D/R 

P 

P 

✓ 

✓ 



Water hyacinth Pontederia crassipes WoNS D/R 

P 

P 

✓ 

✓ 



GRASS 

Aleman grass Echinochloa polystachya -/GBO 

P 

P 

✓ 

✓ 



Gamba grass Andropogon gayanus WoNS D†/R 

E 

P 



✓ 

✓ 

Giant rat’s tail grass Sporobolus spp. -/R 

P 

P 



✓ 

✓ 

Grader grass Themeda quadrivalvis D†/GBO 

C 

C ‡ 



✓ 

✓ 

Hymenachne Hymenachne amplexicaulis WoNS D/R 

P 

P 

✓ 

✓ 



Thatch grass Hyparrhenia rufa D/GBO 

P 

n 



✓ 

✓ 

BROADLEAVED HERB 

Bathurst burr Xanthium spinosum D/GBO 

n 

C ‡ 



✓ 

✓ 

Devils claw Martynia annua D/GBO 

P 

n 





✓ 

Noogoora burr Xanthium occidentale D/GBO 

n 

M 



✓ 

✓ 

Parthenium weed Parthenium hysterophorus WoNS D/R 

P 

C ‡ 



✓ 

✓ 

CLIMBER/VINE 

Rubber vine Cryptostegia grandiflora WoNS D/R 

P 

C 



✓ 

✓ 

Ornamental rubber vine Cryptostegia madagascariensis D/R 

P 

P 



✓ 

✓ 

TREE/SHRUB 




WEED AND LEGAL STATUS 

WoNS = Weed of National Significance 

For NT: Weed Management Act 2001 – 

D = declared; † = has a statutory management plan under the 
Act 

For Queensland: Biosecurity Act 2014 – 

P = prohibited matter; R = restricted matter; GBO = only the 
general biosecurity obligation applies 

REGIONAL ACTION 

HABITATS AT RISK 

NT 

QLD 

AQUATIC 

(e.g. river, 
wetland, dam) 

WETTER AREAS 

(e.g. riparian, 
floodplain, drain) 

DRIER AREAS 

(e.g. grassland, 
woodland) 

Athel pine Tamarix aphylla WoNS D†/R 

E 

C ‡ 



✓ 



Barleria Barleria prionitis D/GBO 

n 

C ‡ 



✓ 

✓ 

Bellyache bush Jatropha gossypiifolia WoNS D†/R 

C 

C 



✓ 

✓ 

Calotrope Calotropis procera, C. gigantea D/GBO 

M 

M 





✓ 

Chinee apple Ziziphus mauritiana D†/R 

C 

C ‡ 



✓ 

✓ 

Coffee bush Leucaena leucocephala -/GBO 

M 

P 



✓ 



Lantana Lantana camara WoNS D/R 

P 

P 







Madras thorn Pithecellobium dulce -/R 

n 

E 







Mesquite Prosopis spp. WoNS D†/PR 

E 

C ‡ 



✓ 

✓ 

Mimosa Mimosa pigra WoNS D†/R 

E 

P 

✓ 





Neem Azadirachta indica D†/GBO 

C 

C 



✓ 

✓ 

Parkinsonia Parkinsonia aculeata WoNS D/R 

M 

M 



✓ 

✓ 

Pond apple Annona glabra WoNS D/R 

P 

P 

✓ 

✓ 



Prickly acacia Vachellia nilotica WoNS D/R 

E 

C ‡ 



✓ 

✓ 

Siam weed Chromolaena odorata D/R 

P 

P 



✓ 

✓ 

Sicklepod Senna obtusifolia, S. hirsuta, S. tora D/R 

n 

P 



✓ 

✓ 

Yellow bells Tecoma stans -/R 

n 

C ‡ 



✓ 

✓ 

Yellow oleander Cascabela thevetia -/R 

M 

C ‡ 



✓ 

✓ 

CACTI/SUCCULENTS 

Bunny ears Opuntia microdasys WoNS D/R 

P 

E 





✓ 

Coral cactus Cylindropuntia fulgida WoNS D/R 

P 

C 







Engelmann’s prickly pear Opuntia engelmannii WoNS D/P 

P 

E 







Harrisia cactus Harrisia martinii, H. tortuosa, H. pomanensis 
D/R 

P 

C ‡ 







Mother of millions Bryophyllum delagoense -/R 

P 

C‡ 







Other opuntioid cacti Opuntia spp., Cylindropuntia spp., 
Austrocylindropuntia spp. WoNS D/PR 

P 

P 









For regional actions: 

P = alert weed for prevention and early intervention 

E = eradication target (few infestations known) 

C = strategic control target (control and containment of core infestations, eradication of outlier populations, prevention elsewhere) 

M = widely established; regional management focused on protecting assets at risk 

n = not a regional priority in that jurisdiction 

‡ Restricted to part of catchment only (SGNRM and NWQROC, 2022); otherwise a P 

Sources: NT Government (2021); SGNRM and NWQROC (2022); pers. comm. NT and Queensland government officers 




Table 7-7 lists examples of high-risk pest fish for the Southern Gulf catchments. Certain species are 
formally declared as ‘noxious’ under the NT Fisheries Regulations 1992, or as prohibited or 
restricted matter in Queensland under the Biosecurity Act. Those not declared noxious in the NT 
are still covered by a general precautionary provision that excludes import into the NT and 
possession of non-native fish that are not on the Australian Government’s list of permitted live 
freshwater ornamental fish (DAFF, 2023), or otherwise not listed as a permitted import in 
Schedule 7 of the Regulations. Those not categorised as prohibited or restricted matter in 
Queensland are still subject to the general biosecurity obligation. 

Table 7-7 High-risk freshwater pest fish threats to the Southern Gulf catchments 

PEST FISH AND LEGAL STATUS (NT/QLD) 



LEGAL STATUS 
IF ANY 
(NT/QLD) 

CURRENT DISTRIBUTION 

Alligator gar Atractosteus spatula 

N/R 

Not known to be in the wild in Australia 

Black pacu Piaractus brachypomus 

E/R 

Not known to be in the wild in Australia. Risk of incursion from PNG 

Carp Cyprinus carpio N/R 

N/R 

Not known to be in the wild in the NT 

Cichlids, including tilapia: 

Giant cichlid Boulengerochromis microlepis 

Jaguar cichlid Parachromis managuensis 

Pearl cichlid Geophagus brasiliensis 

Mozambique tilapia Oreochromis mossambicus 

Nile tilapia Oreochromis niloticus 

Spotted tilapia Pelmatolapia mariae 

Texas cichlid Herichthys cyanoguttatus 

N/R 
E/GBO 
E/GBO 
N/R 
N/P 
N/R 
E/GBO 

Jaguar, pearl and Texas cichlid and Mozambique and spotted tilapia 
present in the wild in Queensland 

Mozambique tilapia and pearl cichlid also present in the wild in WA. 

Giant cichlid not known to be in the wild in Australia 

Nile tilapia an incursion risk from northern Torres Strait 

Climbing perch Anabas testudineus 

N/R 

Risk of incursion from northern Torres Strait 

Gambusia (mosquito fish) Gambusia holbrooki 

N/R 

Not known to be established in the NT (eradicated in Darwin and Alice 
Springs). Recorded in the wild across Queensland and parts of WA 

Guppy Poecilia reticulata 

GBO 

Recorded in Darwin and Nhulunbuy in the NT. Likely to be present 
elsewhere 

Marbled lungfish Protopterus aethiopicus 

N/R 

Not known to be in the wild in Australia 

Oriental weatherloach Misgurnus anguillicaudatus 

N/R 

Not known to be in the wild in the NT 

Oscar Astronotus ocellatus 

GBO 

Not known to be in the wild in the NT. Present in the wild in Queensland 

Platy Xiphophorus maculatus 

GBO 

Present in the wild in Darwin and Nhulunbuy in the NT, and in eastern 
Queensland 

Siamese fighting fish Betta splendens 

GBO 

Established in the Adelaide River catchment in the NT. Not known to be 
in the wild elsewhere in Australia 

Spotted gar Lepisosteus oculatus 

N/R 

Not known to be in the wild in Australia 

Swordtail Xiphophorus hellerii 

GBO 

Present in the wild in Darwin and Nhulunbuy in the NT, and in eastern 
Queensland 



For NT: Fisheries Regulations 1992 – N = noxious, E = excluded for import and possession 

For Queensland: Biosecurity Act 2014 – P = prohibited matter, R = restricted matter, GBO = only the general biosecurity obligation applies 

Source: NT Government, 2024a.; Queensland Government, 2023b 




Terrestrial invertebrates 

Terrestrial invertebrates can also be high-impact invasive species. For example, certain exotic ants 
can form ‘super colonies’ from which they outcompete native ants, consume native invertebrates, 
small invertebrates and seeds, and affect people through stinging and infesting buildings. Some 
ant species ‘farm’ sap-sucking scale insects that are pests of horticultural crops and native plants. 
Non-native ants can be introduced in pot plants, soil or among other materials. 

Yellow crazy ant (Anoplolepis gracilipes) is established in parts of eastern Queensland and has also 
been detected in Darwin and Arnhem Land. Browsing ant (Lepisiota frauenfeldi) has been the 
subject of a national eradication program, including in Darwin and Kakadu in the NT and at the 
Port of Brisbane. Other national eradication programs continue for red imported fire ant (RIFA; 
Solenopsis invicta) in south-east Queensland and electric ant (Wasmannia auropunctata) in far 
north Queensland (Outbreak, 2024; Environment and Invasives Committee, 2019). The national 
eradication program for RIFA has cost $596 million (Outbreak, 2023b). 

Diseases 

Examples of diseases that affect multiple species of native, ornamental and crop plants are myrtle 
rust and phytophthora (Phytophthora spp.). They can cause the death of plants, including 
established shrubs and trees. 

7.4.3 Preventing, responding to and managing biosecurity threats 

Biosecurity can be categorised into three broad approaches: 

•Prevention - taking measures to stop movement along pathways of spread, whether thatbe at the international or state border, to and within a catchment, or between and withinproperties
•Incursion response - undertaking surveillance to detect new pests, weeds or diseases andattempting eradication upon detection, where feasible and cost-beneficial to do so
•Ongoing management – managing a pest, weed or disease that is firmly established in anarea (i.e. is not feasible to eradicate), with control measures regularly applied to containfurther spread and/or mitigate impacts.


The invasion curve (Figure 7-10) is commonly used as a visual representation of biosecurity actions 
taken at various stages of pest invasion. It applies at any scale from national down to an individual 
property. Prevention and eradication generally cost far less than the ongoing management which 
is needed for widely established species (i.e. containment and impact mitigation), although 
improved management tools may substantially reduce long-term costs. 


 

For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 7-10 The invasion curve with biosecurity actions taken at various stages 

Source: J. Virtue 

Shared responsibility at all levels 

Effective biosecurity requires a collaborative approach between government, industry and 
community, from the organisational to the individual level. Such ‘shared responsibility’ includes 
taking action to limit the risk of entry and spread of new pests, weeds and diseases, routinely 
looking for biosecurity threats and reporting if and when detected, and collaborating in 
coordinated control programs across land tenures. Everyone has a duty of care (whether legal or 
moral) to not pose a biosecurity risk to others, including to not harbour invasive species that may 
threaten economic, environmental, social or cultural impacts on neighbouring land uses. 

The biosecurity systems of Queensland and the NT (NT Government, 2016; Queensland Gov, 
2024a) are nested in the national biosecurity system of Australia’s border quarantine and states’ 
domestic quarantine and control program arrangements (DAFF, 2022a). Broadly defined, the 
national biosecurity system consists of the combined Australian, state and territory governments’ 
biosecurity legislative frameworks that seek to prevent pests, weeds and diseases entering, 
establishing, spreading and having an impact in Australia. It involves cooperation and collaboration 
between jurisdictions, and working with and supporting industry and community to involve 
multiple organisations across Australia as biosecurity partners. Various national agreements, plans 
and governance arrangements drive this shared responsibility ethos. 

The following sections describe prevention, incursion response and ongoing management 
activities for plant industries, aquaculture and invasive species in the Southern Gulf catchments, 
within local, state and national contexts. 


Biosecurity in plant industries 

Farm biosecurity planning 

In practice, most plant industry biosecurity activities – whether prevention, preparedness, 
surveillance, elimination, containment or ongoing management – occur at the property level. This 
level is where the relationship between expenditure on crop protection and maintaining profit-
driven productivity and market access is most direct. 

Developing and implementing a farm biosecurity plan is an effective means to prevent the 
introduction and establishment of new pests, weeds and diseases, and to limit the spread and 
impacts of those which are already established. Standard guidance is available on developing such 
plans (AHA and PHA, n.d.), which cover hygiene practices for pathways of introduction (e.g. 
certified seed, machinery and vehicle washdowns, restricted movement of visitors), routine 
surveillance and quick responses to any on-farm identified biosecurity risks. Associated with 
implementing these are signage (e.g. Figure 7-11), staff training, mapping, visitor management, 
record keeping, reporting and annual activity planning. 

A farm biosecurity plan is informed by the key biosecurity threats to the crops being grown and 
broader invasive species risks. A plan should cover both incursion risks and those pests, weeds and 
diseases already present. It also needs to align with government regulatory requirements and 
industry standards. 

 

For more information on this figure please contact CSIRO on enquiries@csiro.au
Figure 7-11 Farm biosecurity signage available through www.farmbiosecurity.com.au 

Regulatory prevention 

Government regulation and policy for plant biosecurity in the Southern Gulf catchments is 
primarily governed by the Queensland Biosecurity Act or the NT Plant Health Act, depending on 
where a property is located. It is important to be aware of any differences in legal requirements 
between the jurisdictions in moving equipment and plant materials across the borders. 

In Queensland, plant pests, weeds and diseases may be listed in the Biosecurity Act as ‘prohibited’ 
(not established in the state) or ‘restricted’ (established in parts of the state and subject to strict 
controls). There are also declared ‘far northern pests’ that pose a risk of entry into Queensland 
from PNG, via the Torres Strait and Cape York Peninsula. Both declared and non-declared pests, 
weeds and diseases are also subject to the Act’s general biosecurity obligation. In Queensland, 
everyone has a general biosecurity obligation and must take all reasonable and practical steps to 
prevent or minimise biosecurity risk and to minimise the likelihood of causing an adverse 
biosecurity event and any harmful effects that risk could have, including not doing anything that 
could make matters worse. 


The Northern Territory plant health manual provides a consolidated list of all declared plant pests 
and diseases in that jurisdiction (DITT, 2023), specifying those which must be reported if detected 
in the NT. 

Each jurisdiction has entry conditions for all commercial and non-commercial movement of plants 
and plant products and other potential vectors of plant pests and diseases (DITT, 2023; 
Queensland Government, 2023c). 

For example, the NT restricts the entry of maize and soybean seed due to disease risks and the 
entry of nursery stock due to risk of introducing scale insects and sucking insects. Soil attached to 
used farm machinery, containers and earth-moving machinery may carry pests or diseases such as 
nematodes, snails, Phytophthora or Fusarium. Hence these items are legally required to be clean 
of soil, and a permit may be required for their entry into NT. In relation to used machinery for 
cotton production, the NT seeks to retain its ‘area freedom’ status for cotton fusarium wilt 
(Fusarium oxysporum f. sp. vasinfectum), which is established in cotton-growing areas in 
Queensland and NSW (Le et al., 2020). 

Examples of Queensland movement restrictions include a hygiene requirement for equipment 
from interstate that has been used for planting, producing or harvesting a cucurbit crop, to 
minimise the transmission of CGMMV. There are also restrictions on moving soil or other carriers 
of RIFA or electric ant (e.g. mulch, compost) out of their respective biosecurity zones within 
Queensland (Queensland Government, 2023d). 

To access interstate markets, produce must meet the respective quarantine specifications and 
protocols, so as not to inadvertently introduce pests or diseases declared in those jurisdictions. 
This typically requires an inspection and the issue of a certificate verifying that conditions have 
been met or that the property is in an area known to be free of a specific pest of concern (DITT, 
2023). For example, SA has movement restrictions (as of February 2024) on the entry of melons 
and other hosts of melon thrips (Thrips palmi) from jurisdictions where it is known to occur, 
including the NT and Queensland (PIRSA, 2024). Current information on moving plant goods 
interstate is compiled on the Australian Interstate Quarantine website (Subcommittee on 
Domestic Quarantine and Market Access, 2024). 

Exports to overseas markets similarly must meet Australian standards and any additional entry 
requirements from the importing countries for the product (DAFF, 2024b). This includes 
certification and supporting documentation relating to area freedom and/or treatments applied 
for specific pests, weeds and/or diseases. Depending on the country, there also may be maximum 
residue limits, or even nil tolerances, for specific pesticides. Exports are regulated by the 
Australian Government through the Commonwealth Export Control Act 2020 and associated rules 
for particular produce and products. 

Incursion response 

Most plant industries have national biosecurity, surveillance and/or preparedness plans for high-
risk exotic pests and diseases that pose national incursion risks (PHA, 2024a). Their entry into 
Australia is prevented by the Australian Government’s pre-border and border quarantine 
requirements under the Commonwealth Biosecurity Act 2015. The Australian Government’s 
Northern Australia Quarantine Strategy is an ongoing surveillance program that seeks to detect 
incursions from countries to Australia’s north (DAFF, 2024a). 


Plant Health Australia (PHA) is the custodian of the Emergency Plant Pest Response Deed (EPPRD; 
Anon., 2024), which specifies how governments and affected industries undertake collaborative 
national eradication responses, including cost sharing and decision making. PLANTPLAN provides 
accompanying national guidelines for managing responses to emergency plant pest incidents at 
national, state or territory, and local levels (PHA, 2022). For example, banana freckle (Phyllosticta 
cavendishii) is currently the subject of an EPPRD national eradication program in the NT (Outbreak, 
2023a). 

Ongoing management 

Best management practice guides for control of established pests, weeds and diseases are 
available through the research and development corporations, other industry organisations and 
state primary industries departments, with some specific to cropping in northern Australia (e.g. 
DPIF, 2014; NT Farmers, 2022). These extension materials focus on integrated management 
approaches that combine a range of control practices (e.g. chemical, physical and biological 
control methods). The cotton industry has a broader online best management practice assurance 
system (myBMP, 2024), which includes modules on integrated pest management and pesticide 
management. Additionally, the Grains Farm Biosecurity Program is an initiative to improve the 
management of, and preparedness for, biosecurity risks in the grains industry at the farm and 
industry levels (PHA, 2024b). 

Pesticides must be approved for use by the Australian Pesticides and Veterinary Medicines 
Authority (APVMA) and applied in a manner that aligns with state or territory requirements on the 
use of such chemicals. This includes minimising spray drift, following label requirements for work 
health and safety, and ensuring appropriate applicator skills and licences. There are maximum 
permissible levels for certain pesticides in specified agricultural produce, achieved by following 
pesticide label (or APVMA permit) requirements regarding approved crops, rates and frequency of 
application, and withholding periods (NT Government, 2024c; Queensland Government, 2023e). 

A key consideration for ongoing management on-farm is ensuring chemical control tools are used 
tactically to limit the risk of developing insecticide, herbicide and fungicide resistance (Grains 
Research and Development Corporation, 2024; CropLife Australia, 2021). For example, growers 
cultivating Bollgard® 3 and Roundup Ready Flex® cotton must follow on-farm stewardship 
packages (Bayer, 2023). 

Growers whose crop production is affected by native animals may require NT Government permits 
before taking any lethal control measures. On-property storage of harvested grain needs 
consideration of physical and chemical means to prevent beetle and weevil pests (Grain Storage 
Extension Project, 2024). 

Biosecurity in aquaculture 

Plan for prevention 

Prevention in aquaculture starts with enterprise-level biosecurity planning. This is vital in 
protecting aquaculture facilities from disease and parasite risks, which can be difficult to 
eliminate, let alone manage, once established. Planning guides have been developed for various 
industries, including barramundi (Landos et al., 2019) and oyster hatcheries. Preventing entry of 
pathogens into facilities is vital. Growers need to understand the various disease risks and where 
they could come from. Wild-captured broodstock poses a very high risk of introducing endemic 


diseases; stock known to be free from specific diseases should be sourced (Cobcroft et al., 2020). 
Diseases may enter a facility via contaminated equipment, workers handling diseased fish, water 
harbouring pathogens, or wild animals such as birds entering ponds (Irvin et al., 2018). Untreated 
source water is a key pathway for disease entry, with pathogen risks coming from wild stocks or, 
potentially, from a nearby, upstream aquaculture facility (Irvin et al., 2018). Pathogen monitoring 
should be ongoing, and emergency response plans should be developed to isolate any detected 
disease occurrence and implement thorough disinfestation procedures. 

Commercial aquaculture in the NT is regulated through the NT Fisheries Act 1998 and the Fisheries 
Regulations 1992. The Regulations prohibit movement or sale of diseased fish and require 
reporting of any legally notifiable diseases detected in aquaculture facilities. Movement of all 
stock is under a permit system, and health assessments are conducted to manage the risk of 
disease movement through movement of aquaculture stock. 

Similar legal provisions apply in Queensland under the Biosecurity Act and Fisheries Act 1994. 
Under the Queensland Biosecurity Act’s general biosecurity obligation, aquaculture enterprises 
are legally obligated to take reasonable and practical measures to minimise the risk and spread of 
disease. Aquaculture farms are required to have a disease management plan as a standard 
condition of development approval under the state’s Planning Act 2016. Approval from Fisheries 
Queensland is required to move live aquatic animals within the state or interstate, and such 
movements must comply with a specified health protocol (Queensland Government, 2024b). 
Actual or suspected disease incidents must be reported. 

Incursion response 

AQUAPLAN is the national aquatic animal health strategic plan; it aims to improve border, 
enterprise and regional biosecurity measures, and build surveillance, diagnostic capacity and 
emergency preparedness (DAFF, 2022b). There is also national policy guidance on minimising the 
movement of disease when translocating live aquatic animals for aquaculture and other purposes 
(DAWE, 2020b). 

The NT Government can declare a control area in the event of an actual or likely notifiable disease 
outbreak in an aquaculture facility, providing for limits on further fish movement, halting the 
release of aquaculture water, and/or requiring mandatory treatment or destruction measures for 
fish and contaminated equipment. Similar biosecurity emergency restrictions and prohibitions can 
be applied under the Queensland Biosecurity Act. 

Having aquaculture biosecurity plans is not just about protecting the enterprise. There is also a 
duty of care to protect nearby wild fisheries which may be exposed to disease from discharge 
waters, escapee infected animals or fish movement via predatory birds. Prompt isolation of 
affected ponds and preventing water flow from these to the surrounding environment are vital in 
the event of a disease outbreak. The escape of white spot syndrome virus from prawn farms in 
south-east Queensland and northern NSW led to restrictions on commercial and recreational 
fishing of crustaceans in adjacent catchments, with substantial local economic impacts. 

Ongoing management 

Treatment options are limited for aquatic diseases, particularly viral pathogens. Veterinary 
medicines, such as antibiotics for bacterial disease in barramundi, are available. However, their 
use can require veterinary permission in order to manage risks of antimicrobial resistance, both in 


the aquaculture facility itself and the broader food chain. Fungal and external protozoan 
pathogens may be able to be suppressed using altered salinity bathing. Most fundamental is the 
need for a high-quality rearing environment, with optimal water conditions and feed supply, to 
reduce the risk of stress-induced disease outbreaks (Irvin et al., 2018). 

Biosecurity for invasive species 

Irrigation development planning 

Regional and local irrigation and industry infrastructure development, including road networks, 
should include prevention and management of invasive species in their environmental planning 
processes. This includes meeting legal obligations under the various Acts mentioned above, a 
stocktake of present distribution of declared species, and risk mitigation to limit pathways of 
introduction of new invasive species during construction and ongoing maintenance. Ongoing 
monitoring should be implemented for both terrestrial and aquatic pests (vertebrate and 
invertebrate) and weeds. 

Weeds 

The Southern Gulf catchments fall within scope of the Katherine regional weeds strategy 2021–
2026 (NT Government, 2021) and the North West Queensland regional biosecurity plan 2022–2027 
(SGNRM and NWQROC, 2022). These define priority declared weed control programs within the 
study area as coordinated by the NT Government or by local governments in Queensland. 

Under the Queensland Biosecurity Act, all landholders are responsible for taking all reasonable 
and practical steps to minimise the risks associated with invasive plants under their control, as per 
the general biosecurity obligation. Prohibited plants are not known to be established in 
Queensland and must be reported. Restricted plants are high-risk weeds that are established in 
parts of Queensland, and legal requirements are in place to prevent their further spread, including 
reporting their presence and/or prohibiting their sale, movement and/or cultivation. 

Under the NT Weed Management Act, every landholder is legally obliged to take all reasonable 
measures to prevent land from being infested with a declared weed and to prevent a declared 
weed from spreading. There are also prohibitions on buying, selling, cultivating, moving or 
propagating any declared weed, and a legal requirement to notify a declared weed’s presence if it 
is new to a property. Certain declared plants, such as Gamba grass, neem (Azadirachta indica) and 
bellyache bush (Jatropha gossypiifolia), also have statutory management plans (Table 7-6), which 
require specific management actions to be implemented by all landholders. 

The NT Government website and other Australian websites (e.g. www.weeds.org.au) provide best 
management practice information on how to control declared weeds and other invasive plants, 
including registered herbicides and biological control agents. In particular, much information is 
available on management on WoNS (CISS, 2021). 

In selecting new crops and pastures for planting in the Southern Gulf catchments, landholders 
should consider the crops’ weed risks to the surrounding environment. Many northern Australia 
pasture grasses can be invasive and cause significant biodiversity and cultural impacts in the 
landscape (DSEWPC, 2012). An example method for considering weed risks is the WA 
Government’s environmental weed risk assessment process for plant introductions to pastoral 
lease land (Moore et al., 2022). 


Cotton is not considered to pose a significant environmental weed threat in northern Australia 
(Office of the Gene Technology Regulator, 2024). It has been sporadically recorded across 
northern Australia on roadsides, near cropping fields, in irrigation drains and adjacent to natural 
watercourses (Atlas of Living Australia, 2024). However, modern varieties’ ability to establish and 
reproduce is constrained by dense lint around seeds impeding germination, seed predation, 
seasonal drought, competition from established plants, herbivory and fire (Eastick and Hearnden, 
2006; Rogers et al., 2007). Nonetheless, it is recommended that transport of harvested cotton is 
covered to reduce the likelihood of spread outside cultivation (Addison et al., 2007). 

Terrestrial vertebrate pests 

Large feral herbivores are controlled through mustering, trapping, baiting and/or aerial or ground 
shooting programs, depending on the approved humane control methods for particular species 
(CISS, 2024; NT Government, 2024d; Queensland Government, 2018). For long-term suppression, 
programs need to be conducted over multiple years at a subregional scale across all infested 
properties, taking account of animal movements and sub-populations. Ongoing control is then 
needed to maintain low densities. 

7.5 Off-site and downstream impacts 

7.5.1 Introduction 

Northern Australian river systems are distinctive as they have highly variable flow regimes, unique 
species composition, low human population densities and, in some cases, naturally high turbidity 
(Brodie and Mitchell, 2005). Primary influences on groundwater and surface water quality include 
increased sediment loads associated with land clearing, grazing, agriculture and late dry-season 
fires, and nutrient pollution from agricultural and pastoral land use (Dixon et al., 2011). These can 
affect the water quality of not just groundwater and rivers, lakes and wetlands but also estuarine 
and marine ecosystems. 

The principal pollutants from agriculture are nitrogen, phosphorus, total suspended solids, 
herbicides and pesticides (Lewis et al., 2009; Kroon et al., 2016; Davis et al., 2017). Water losses 
via runoff or deep drainage are the main pathways by which agricultural pollutants enter water 
bodies. The type and quantity of pollutants lost from an agricultural system and ultimately the 
quality of the receiving surface water and groundwater is significantly influenced by a wide range 
of factors, including environment factors such as climate, hydrology, soils, hydro geochemistry and 
topography as well as land use and management factors such as crops, cropping system, method 
of application of irrigation water, tailwater management, quality of source water, location and 
proximity to drainage lines and conservation and irrigation practices. Due to the high dependency 
of the location, design, implementation and operation of an irrigation development on water 
quality predicting water quality impacts associated with irrigated agriculture is very difficult. 
Rather the influence of these environment and management factors on water quality are 
discussed in more detail in the companion technical report on water quality (Motson et al., 2024). 

Most of the science in northern Australia concerned with the downstream impacts of agricultural 
development has been undertaken in the eastern-flowing rivers that flow into the Great Barrier 
Reef lagoon. Comparatively little research on the topic has been done in the rest of northern 


Australia and there is need for caution in transposing findings from north-eastern Australia, which 
is different in terms of climate, geomorphology and patterns of settlement to those parts of 
northern Australia west of the Great Dividing Range. Nonetheless experience from north-eastern 
Australia has been that the development of agriculture has been associated with declining water 
quality (Lewis et al., 2009; Mitchell et al., 2009; De’ath et al., 2012; Waterhouse et al., 2012; 
Thorburn et al., 2013; Kroon et al., 2016). Pollutant loads in north-eastern Australian rivers 
(typically those in which agriculture dominates as a land use) are estimated to have increased 
considerably since European settlement in the 1850s for nitrogen (2 to 9 times baseline levels), 
phosphorus (3 to 9 times), suspended sediment (3 to 6 times) and pesticides (~17,000 kg) (Kroon 
et al., 2016). 

7.5.2 Managing irrigation drainage 

Degraded water quality can cause a loss of aquatic habitat, biodiversity, and ecosystem services. 
Increased nitrogen and phosphorus can cause plankton blooms and weed infestation, increase 
hypoxia (low oxygen levels) and result in fish deaths. Pesticides, used to increase agricultural 
productivity, can harm downstream aquatic ecosystems, flora and fauna. As with fertiliser 
nutrients, pesticides can enter surface water bodies and groundwater via infiltration, leaching, and 
runoff from rainfall events and irrigation. These chemicals can be toxic to non-target species, such 
as aquatic life and humans, affecting nervous systems, immune systems, photosynthesis and 
growth (Cantin et al., 2007; Kaur et al., 2019; Naccarato et al., 2023). They can be carcinogenic 
(Mohanty and Jena, 2019) and cause multiple sub-lethal effects that can disrupt the ecological 
balance of aquatic systems and degrade aquatic communities (Giglio and Vommaro, 2022; Miller 
et al., 2020; Wang et al., 2022). 

Other water quality variables that can have a significant effect on the health of aquatic species, 
communities and ecosystems include salinity, pH, and suspended sediments. Increased salinity, 
indicated by increased EC and TDS, can interfere with osmoregulatory processes, harming those 
species not adapted to saline conditions (Hart et al., 2003). Variations in the pH of a water body 
can negatively affect an organism’s biochemical processes, leading to altered behaviour, 
functioning, growth, and even survival (US EPA, 2024). In aquatic ecosystems, elevated loads of 
suspended sediment can smother habitats and benthic invertebrates, affect the feeding and 
respiratory systems of aquatic species, and reduce light penetration, affecting photosynthetic 
activity (Chapman et al., 2017). Table 7-8 provides a summary of how changes in key water quality 
variables affect aquatic ecology and human health. 

Table 7-8 Water quality variables reviewed – their impacts on the environment, aquatic ecology and human health 

WATER 
QUALITY 
VARIABLE 

 

THREATS TO AQUATIC ECOLOGY AND HUMAN HEALTH 

REFERENCE 

Nutrients 

Nitrogen 

Forms of nitrogen in freshwater systems include: nitrate (NO3), nitrite 
(NO2), ammonia (NH3) and ammonium (NH4). 

In excessive quantities, contributes to eutrophication and algal 
blooms, which can deplete oxygen and create hypoxic/anoxic 
conditions harmful to aquatic life. 

Health threat to humans, particularly infants, and mammals 

Carpenter et al. 
(1998) 

Phosphorus 

High concentrations may lead to eutrophication and algal blooms, 
which can deplete oxygen and create hypoxic/anoxic conditions 

Mainstone and 
Parr (2002) 






WATER 
QUALITY 
VARIABLE

THREATS TO AQUATIC ECOLOGY AND HUMAN HEALTH

REFERENCE 

Salinity 



Can affect osmoregulatory processes of aquatic species, harming 
aquatic life not adapted to saline water. Significant increases in 
salinity may compromise the integrity of freshwater ecosystems 

Hart et al. (2003) 

Other 

Total Suspended 
Solids 

Can smother habitats, reduce light penetration (through increasing 
turbidity), and affect the feeding and respiratory systems of aquatic 
organisms 

Chapman et al. 
(2017) 

pH 

Variations can negatively affect aquatic life stages, affecting their 
biochemical processes. Preferred pH range of 6.4–8.4 for aquatic 
species 

US EPA(2024) 

harmful to aquatic life 

Dissolved Organic 
Carbon 

A proxy for dissolved organic matter, affecting water clarity, 
temperature, biogeochemical processes, food webs and ecosystem 
productivity. Dissolved Organic Carbon may exacerbate 
eutrophication and hypoxia in aquatic ecosystems, and cause 
problems in drinking water treatment processes 

Palviainen et al. 
(2022) 

Pesticide 
groups 

Arylurea 

Includes pesticides such as Diuron® and tebuthiuron. May inhibit 
photosynthesis in plants and aquatic species. These pesticides are less 
soluble in water and better absorbed by the soil 

Cantin et al. 
(2007), Fojut et al. 
(2012) 

Carbamates 

Broad-spectrum pesticides that affect nerve impulse transmission and 
are highly toxic to vertebrate species. Suspected carcinogens and 
mutagens. Relatively low persistence; not easily adsorbed to soil 
particles 

Kaur et al. (2019), 
Rad et al. (2022) 

Chloroacetanilides 

Affects cell division, disrupting aquatic plant growth; also toxic to 
aquatic insects. Persistent. Low binding affinity to soil particles but 
highly water soluble; therefore, it has a high capacity for leaching into 
the groundwater and ending up in surface water. Carcinogens with 
moderate to high chronic toxicity 

ANZG (2020), 
Mohanty and Jena 
(2019) 

Dinitroanilines 

Broad-spectrum herbicides with low water solubility; considered non-
mobile in soil. Affect seed germination and root growth in plants. 
Variable, species-specific toxicity ranging from slightly to highly acute. 
Hazardous to animals and humans in sub-lethal concentrations. 
Known bioaccumulation in and acute toxicity to aquatic organisms 

Giglio and 
Vommaro (2022) 

Neonicotinoids 

Highly toxic to invertebrates, particularly aquatic insects. Sub-lethal 
toxicity in fish. High solubility. High chronic risk to global freshwater 
ecosystems. Suspected to be carcinogenic 

Wang et al. (2022) 

Organochlorines 

Persistent organic pollutants that can bioaccumulate in fatty tissues. 
These pesticides are toxic to humans and other animals, and they are 
highly toxic to most aquatic life 

DCCEEW (2021) 

Organophosphates 

Broad-spectrum pesticides that control a wide range of pests via 
multiple functions. Organophosphate insecticides are toxic to both 
vertebrates and invertebrates, disrupting nerve impulse transmission 

Kaur et al. (2019) 

Phenylpyrazole 

These pesticides disrupt nerve impulse transmission. Toxic to aquatic 
organisms and birds. Phenylpyrazole pesticides, such as Fipronil, have 
been found to degrade stream communities. Moderate water 
solubility and hydrophobicity. Slightly mobile in soils. Moderate 
persistence 

Gao et al. (2020), 
Miller et al. (2020) 

Triazine 

Inhibits photosynthesis in plants, potentially leading to reduced plant 
growth and blocks food intake by insect pests. Short to moderate 
persistence depending on soil pH. Adverse and sub-lethal effects on 
terrestrial and aquatic non-target organisms, affecting growth and 
the nervous and immune systems 

Naccarato et al. 
(2023) 




7.5.3 Impacts of irrigated agriculture on water quality 

Fertiliser applications in irrigated agriculture can significantly affect nutrient levels in drainage 
waters, leading to increased concentrations of total phosphorous and total nitrogen in surface 
waters during the irrigation season (Barbieri et al., 2021; Mosley and Fleming, 2010). The type of 
cropping system employed also plays a crucial role in determining groundwater nutrient 
concentrations. For example, variations in cropping practices, such as mulch-till versus ridge-till 
systems, can result in substantial differences in nitrate levels, underscoring the importance of 
adopting best management practices for protecting groundwater quality (Albus and Knighton, 
1998). 

Surface water quality is similarly affected by nutrient inputs, with concentrations of total 
phosphorous often decreasing as streamflow increases, suggesting a dilution effect (Skhiri and 
Dechmi, 2012). However, this relationship can be inconsistent, as dilution effects may not be 
evident when only storm event streamflow is considered. Instead, total phosphorous 
concentrations are influenced by a combination of factors, including rainfall duration and 
intensity, as well as irrigation and fertiliser application practices. The interplay of these factors 
highlights the complex interactions between rainfall, irrigation, and nutrient management in 
determining both surface water and groundwater quality outcomes. 

Controlled pesticide use is crucial for managing its impact on surface water quality. When 
pesticide application rates are managed and irrigation schedules are aligned with crop growth 
stages, their concentrations are typically low. Pesticide-specific application practices also influence 
runoff concentrations: pesticides that are applied to, and therefore intercepted by, the crop 
canopy have significantly lower surface water concentrations relative to those applied to bare soil 
(Moulden et al., 2006). 

Seasonal hydrology, particularly ‘first-flush’ events following irrigation or significant rainfall, plays 
a critical role in determining water quality (Davis et al., 2013; Yeates, 2016). Studies have shown 
that pesticide concentrations in runoff are highest following initial irrigation events but decrease 
in subsequent events (Davis et al., 2013). Despite this dilution, pesticide concentrations in 
receiving waters can still exceed recommended levels. Similarly, nitrogen concentrations in runoff 
are often higher following early-season rainfall, when crops have not yet fully absorbed available 
nitrogen, leading to increased transport in runoff (Yeates, 2016). 

These findings underscore the importance of implementing sustainable irrigation management 
practices and highlight the need for continuous monitoring and adaptive management to mitigate 
the impacts of agricultural activities on water quality. Ensuring effective management is vital for 
protecting water resources and maintaining the ecological integrity of aquatic ecosystems and 
communities amid agricultural intensification. 

The potential for irrigated agriculture to cause secondary salinisation is discussed in Section 7.6. 

Managing irrigation drainage 

Surface drainage water is water that runs off irrigation developments as a result of over-irrigation 
or rainfall. This is mostly an issue where water is applied using surface irrigation methods (e.g. 
furrow, flood) rather than spray or micro-irrigation methods (e.g. drip, micro-spray). This excess 
water can potentially affect the surrounding environment by modifying flow regimes and changing 


water quality. Hence, management of irrigation or agricultural drainage waters is a key 
consideration when evaluating and developing new irrigation systems and should be given careful 
consideration during the planning and design processes. Regulatory constraints on the disposal of 
agricultural drainage water from irrigated lands are being made more stringent as this disposal can 
potentially have significant off-site environmental effects (Tanji and Kielen, 2002). Hence, 
minimising drainage water through the use of best-practice irrigation design and management 
should be a priority in any new irrigation development in northern Australia. This involves 
integrating sound irrigation systems, drainage networks and disposal options so as to minimise off-
site impacts. 

Surface drainage networks must be designed to cope with the runoff associated with irrigation, 
and also the runoff induced by rainfall events on irrigated lands. Drainage must be adequate to 
remove excess water from irrigated fields in a timely manner and hence reduce waterlogging and 
potential salinisation, which can seriously limit crop yields. In best-practice design, surface 
drainage water is generally reused through a surface drainage recycling system where runoff 
tailwater is returned to an on-farm storage or used to irrigate subsequent fields within an 
irrigation cycle. 

The quality of drainage water depends on a range of factors including water management and 
method of application, soil properties, method and timing of fertiliser and pesticide application, 
hydrogeology, climate and drainage system (Tanji and Kielen, 2002). These factors need to be 
taken into consideration when implementing drainage system water recycling and also when 
disposing of drainage water to natural environments. 

A major concern with tailwater drainage is the agricultural pollutants derived from pesticides and 
fertilisers that are generally associated with intensive cropping and are found in the tailwater from 
irrigated fields. Crop chemicals can enter surface drainage water if poor water application 
practices or significant rainfall events occur after pesticide or fertiliser application (Tanji and 
Kielen, 2002). Thus, tailwater runoff may contain phosphate, organic nitrogen and pesticides that 
have the potential to adversely affect flora and fauna and ecosystem health, on land and in 
waterways, estuaries or marine environments. Tailwater runoff may also contain elevated levels of 
salts, particularly if the runoff has been generated on saline surface soils. Training irrigators in 
responsible application of both water and agrochemicals is therefore an essential component of 
sustainable management of irrigation. 

As tailwater runoff is either discharged from the catchment or captured and recycled, it can result 
in a build-up of agricultural pollutants that may ultimately require disposal from the irrigation 
fields. In externally draining basins, the highly seasonal nature of flows in northern Australia does 
offer opportunities to dispose of poor-quality tailwater during high-flow events. However, 
downstream consequences are possible, and no scientific evidence is available to recommend 
such disposal as good practice. Hence, consideration should be given to providing an adequate 
understanding of the downstream consequences of disposing of drainage effluent, and options 
must be provided for managing disposal that minimise impacts on natural systems. 


7.5.4 Natural processing of water contaminants 

While elevated contaminants and water quality parameters can harm the environment and human 
health, there are several processes by which aquatic ecosystems can partially process 
contaminants and regulate water quality. Denitrification, for example, is the process of anaerobic 
microbial respiration which, in the presence of carbon, reduces nitrogen to nitrous oxide and 
dinitrogen gas (Martens, 2005). Therefore, denitrification is a naturally occurring process that can 
remove and reduce nitrogen concentrations within a water body. Pesticides can also be naturally 
removed from water via chemical oxidation, microbial degradation, or ultraviolet photolysis, 
although some chemically stable pesticides are highly persistent, and their microbial degradation 
is slow (Hassaan and El Nemr, 2020). Phosphorus, however, does not have a microbial reduction 
process equivalent to denitrification. Instead, if it is not temporarily taken up by plants, 
phosphorus can be adsorbed onto the surface of inorganic and organic particles and stored in the 
soil, or deposited in the sediments of water bodies, such as wetlands (Finlayson, 2006). This 
phosphorus can be remobilised into solution and re-adsorbed, resulting in ‘legacy’ phosphorus 
that can affect water quality for many years (Records et al., 2016). 

7.5.5 Water quality considerations relevant to aquaculture 

Aquaculture can be impacted by poor water quality and can also contribute to poor water quality 
unless aquaculture operations are well managed. A summary is provided below, however, for 
more information see Northern Australia Water Resource Assessment report on aquaculture 
viability (Irvin et al., 2018). 

Chemical contaminant risk to aquaculture and the environment 

Hundreds of different chemicals, including oils, metals, pharmaceuticals, fertilisers and pesticides 
(i.e. insecticides, herbicides, fungicides), are used in different agricultural, horticultural and mining 
sectors, and in industrial and domestic settings, throughout Australia. Releasing these chemical 
contaminants beyond the area of target application can contaminate soils, sediments and waters 
in nearby environments. In aquatic environments, including aquaculture environments, fertilisers 
have the potential to cause non-point source pollution. Eutrophication is caused by nutrients that 
trigger excessive growth of plant and algal species, which then form hypoxic ‘dead zones’ and 
potentially elevated levels of toxic un-ionised ammonia (Kremser and Schnug, 2002). This can have 
a significant impact on the health and growth of animals in aquaculture operations, as well as in 
the broader environment. 

Of concern to aquaculture in northern Australia are the risks posed to crustaceans (e.g. prawns 
and crabs) by some of the insecticides in current use. These are classified based on their specific 
chemical properties and modes of action. The different classes of insecticides have broad and 
overlapping applications across different settings. 

The toxicity of organophosphate insecticides is not specific to target insects, raising concerns 
about the impacts on non-target organisms such as crustaceans and fish. Despite concerns about 
human health impacts and potential carcinogenic risks, organophosphates are still one of the most 
broadly used types of insecticide globally, and they are still used in Australia for domestic pest 
control (Weston and Lydy, 2014; Zhao and Chen, 2016). Pyrethroid insecticides have low toxicity 


to birds and mammals, but higher toxicity to fish and arthropods. Phenylpyrazole insecticides also 
pose risks to non-target crustaceans (Stevens et al., 2011). Neonicotinoid insecticides are being 
used in increasing amounts because they are very effective at eliminating insect pests, yet they 
pose low risks to mammals and fish (Sánchez-Bayo and Hyne, 2014). Monitoring data from the 
Great Barrier Reef catchments indicate that the concentration of neonicotinoid insecticides in 
marine water samples is rapidly increasing with widespread use. One significant concern for 
aquaculture is the risk that different insecticides, when exposed to non-target organisms, may 
interact to cause additive or greater-than-additive toxicity. 

Aquaculture discharge water and off-site impacts 

Discharge water is effluent from land-based aquaculture production (Irvin et al., 2018). It is water 
that has been used (culture water) and is no longer required in a production system. In most 
operations (particularly marine), bioremediation is used to ensure that water discharged off-farm 
into the environment contains low amounts of nutrients and other contaminants. The aim is for 
discharge waters to have similar physiochemical parameters to the source water. 

Discharge water from freshwater aquaculture can be easily managed and provides a water 
resource suitable for general or agriculture-specific irrigation. Discharge water from marine 
aquaculture is comparatively difficult to manage and has limited reuse applications. The key 
difference in discharge management is that marine (salty) water must be discharged at the source, 
whereas the location for freshwater discharge is less restrictive and potential applications (e.g. 
irrigation) are numerous. Specific water discharge guidelines vary with aquaculture species and 
jurisdiction. For example, Queensland water discharge policy minimum standards for prawn 
farming include standards for physiochemical indicators (e.g. oxygen and pH) and nutrients (e.g. 
nitrogen, phosphorus and suspended solids) and total volume (EHP, 2013). 

The volume of water required to be discharged or possibly diverted to a secondary application 
(e.g. agriculture) is equivalent to the total pond water use for the season minus total evaporative 
losses and the volume of recycled water used during production. 

A large multidisciplinary study of intensive Australian prawn farming, which assessed the impact of 
effluent on downstream environments (CSIRO, 2013), found that Australian farms operate under 
world’s best practice for the management of discharge water. The study found that discharge 
water had no adverse ecological impact on the receiving environment and that nutrients could not 
be detected 2 km downstream from the discharge point. 

While Australian prawn farms are reported as being among the most environmentally sustainable 
in the world (CSIRO, 2013), the location of the industry adjacent to the World Heritage–listed 
Great Barrier Reef and related strict policy on discharge has been a major constraint to the 
industry’s expansion. Strict discharge regulation, which requires zero net addition of nutrients in 
waters adjacent to the Great Barrier Reef, has all but halted expansion in the last decade. An 
example of the regulatory complexity in this study area is the 14-year period taken to obtain 
approval to develop a site in the Burdekin shire in north Queensland (APFA, 2016). 

In a report to the Queensland Government (Department of Agriculture and Fisheries Queensland, 
2013), it was suggested that less-populated areas in northern Australia, which have less conflict for 
the marine resource, may have potential as areas for aquaculture development. The complex 
regulatory environment in Queensland was a factor in the decision by Project Sea Dragon to 


investigate greenfield development in WA and NT as an alternative location for what would be 
Australia’s largest prawn farm (Seafarms, 2016). 

Today, most farms (particularly marine) use bioremediation ponds to ensure that water 
discharged off-farm into the environment contains low amounts of nutrients and other 
contaminants. The prawn farming industry in Queensland has adopted a code of practice to 
ensure that discharge waters do not result in irreversible or long-term impacts on the receiving 
environment (Donovan, 2011). 

7.6 Irrigation-induced salinity 

7.6.1 Introduction 

Salts occur naturally in all soils and landscapes. The amount of salt present depends on local 
climate, salt store in the geology, landscape position, soil type, the depth to the watertable and 
the quality of the groundwater below the watertable. Naturally occurring areas of salinity, or 
‘primary salinity’, occur in the landscape, with ecosystems adapted to the saline conditions. 

Any change to landscape hydrology, including clearing and irrigation, can mobilise salts, resulting 
in environmental degradation in the form of ‘secondary salinity’. Secondary salinity manifests itself 
in two main forms: irrigation-induced salinity and land clearing induced salinity. In the case of 
irrigation-induced salinity, an increase in drainage below the root zone following applications of 
irrigation water can raise watertables and bring salts to the soil surface. Excessive drainage of 
irrigation water below the root zone tends to more likely occur in coarser-textured soils, 
(Petheram et al., 2002). In Australia, over-irrigation (or overwatering) due to poor irrigation 
practices, together with leakage of water from irrigation distribution networks and drainage 
channels, has caused the watertable level to rise in many irrigated areas. Significant parts of all 
major irrigation areas have watertables that are now close to the land surface (in the vicinity of 2 
to 3 m from the land surface) (Christen and Ayars, 2001). Salts can concentrate in the root zone 
over time as a result of evaporation, which can be a compounding factor. In addition, the process 
by which the salts accumulate in the root zone is accelerated if the groundwater has high salt 
concentrations. 

In the Assessment area, some clay soils do have high levels of salt within 1 to 2 m of the surface, 
depending on their location. Clay soils that have slowly or very slowly permeable subsoils (SGG 9) 
can accumulate salts in the subsoil over time, even in areas receiving high rainfall during the wet 
season. Caution should be applied in the irrigation of poorly drained clay soils (SGG 9). The 
cracking clay soils on the Armraynald Plain, particularly the black soils along the Gregory River 
backplain, have subsoils that are high in salt and susceptible to irrigation-induced secondary 
salinity. 

No evidence of surface salt was found by this survey or past surveys (Christian et al., 1954; Perry et 
al., 1964) of the Southern Gulf catchments, apart from on or near the marine plains (Karumba 
Plains) (see Figure 7-12). However, development of irrigation in the Assessment area is in its 
infancy. 

It should be noted that this section on irrigation-induced salinity provides general information 
regarding soils suitable for irrigation development. The risk of secondary salinisation at a specific 


location in the Southern Gulf catchments can only be properly assessed by undertaking detailed 
field investigations at a local scale. 

7.6.2 Potential sources of salt 

Salt stores in soils 

The salts in the soil and landscape in the Southern Gulf catchments are derived from rainfall, wind, 
the weathering of primary minerals, and former marine sediments in the substrate. The amount of 
salt in the landscape (‘salt store’) depends on the origins of the salts, the degree of geological 
weathering, the climate (particularly the rainfall and the prevailing wind direction), position in the 
landscape, landscape permeability (soils and rock), and watertable dynamics. 

The Southern Gulf catchments have extensive natural surface salinity, on the extratidal salt plains 
along the coast of the Gulf of Carpentaria (Karumba Plain; see Section 2.2.2 and Figure 7-12). 
These plains extend up to 35 km inland and are not considered suitable for irrigation 
development. 




For more information on this figure, please contact CSIRO on enquiries@csiro.au 
Figure 7-12 An extratidal flat on the Karumba Plain near Burketown, with white salt crystals either side of a shallow 
natural drainage line. Salt-tolerant samphire and mangrove species can be seen in the background. 

Photo: CSIRO 

The grey clay soils (SGG 9) north of the Nardoo – Burketown Road on the Armraynald Plain have a 
high risk of salinity if irrigated, due to their proximity to the salty tidal creeks of the Karumba Plain. 
Drainage from irrigation could cause the watertable to rise, intercepting some of the tidal creeks 
and causing a spread of salt beyond the creeks. The risk is much less south of the Nardoo–


Burketown Road. 




Figure 7-13 Example of salt-affected areas on the northern part of the Armraynald Plain 

Photo: Esri, Maxar, Earthstar Geographics, and the GIS User Community 

The black clay soils (SGG 9) on the backplain of the Gregory River contain salts at depths of more 
than 1.5 m. The salts are likely to be derived from the weathering of the underlying Pleistocene 
marine and terrestrial sediments and from cyclic (rain and wind-blown) sources. If these soils are 
irrigated, there is a risk that the watertable will rise and carry this salt up to within the plant root 
zone. 

The grey clay soils (SGG 9) around Gregory and the brown clay soils on the east of the Leichhardt 
River on the Armraynald Plain have much less salt in the subsoil, and thus the risk of irrigation-
induced salinity is lower. 

The clay soils (SGG 9) on the Barkly Tableland have low subsoil salt levels. Where they are 
underlain by porous limestone and dolomite, a build-up of salts due to irrigation is not expected. 

The sandy soil (SGG 6), loamy soil (SGG 4) and sand or loam over friable brown, yellow and grey 
clay soils (SGG 1.2) on the Doomadgee Plain also have negligible salts within the soil profile. 
However, due to other risk factors, care would need to be exercised when clearing the silver box, 


bloodwood and broad-leaf paperbark savanna landscapes for rainfed or irrigated cropping. 
Groundwater aquifers contained by underlying ferricrete, the likelihood of soils having variable 
depths, and the very gently undulating plain make it difficult to manage irrigation water discharge 
on lower slopes and in drainage depressions, causing salts to accumulate in these areas over time. 
In places where these soils are shallow, it would be necessary to monitor the depths of rising 
watertables and manage irrigation rates accordingly. In addition, excessive irrigation rates are 
likely to have off-site impacts in the long term, as the lateral flow of water can ‘wick’ from the 
lower slopes in these landscapes to form scalds. From these scalds, salts can potentially be 
mobilised towards nearby streams. 

Irrigation water as a potential source of salt 

In many irrigation developments around the world, poor-quality irrigation water is the source of 
the salt in secondary salinisation. In the Southern Gulf catchments, however, the river water is 
relatively fresh, and the aquifers with potential for groundwater resource development are also 
relatively fresh (see Section 2.5.2), so are unlikely to be a source of salt. However, there is a risk 
that in some cases certain levels of localised groundwater extraction from aquifers could result in 
the entrainment of poorer quality water from the surrounding aquifers or aquitards over time, 
thereby reducing the overall quality of the groundwater applied to crops. The potential for this 
occurring would require a local, site-specific investigation. 

7.6.3 Rise in watertable level and changes in groundwater discharge due to irrigation 
development 

The extent to which the watertable rises close to the surface depends on: 

•the initial depth to the watertable
•the amount of groundwater recharge (from root zone drainage)
•the size of the irrigation area (which dictates the total volume of water added to the landscape)
•the lateral distance to rivers (which act as a drainage boundary, thus reducing the height of thegroundwater mound under irrigation)
•aquifer parameters, including saturated hydraulic conductivity, aquifer thickness and specificwater yield.


Generic modelling results evaluating the risk of watertable rise are documented in the Flinders 
and Gilbert Agricultural Resource Assessment technical report on surface water – groundwater 
connectivity (Jolly et al., 2013). 

Site-specific assessments need to be undertaken to determine the extent of the secondary salinity 
risk. 


7.7 References 

Addison SJ, Farrell T, Roberts GN and Rogers DJ (2007) Roadside surveys support predictions of 
negligible naturalisation potential for cotton (Gossypium hirsutum) in north‐east Australia. 
Weed Research, 47(3), 192–201. DOI:10.1111/j.1365-3180.2007.00561.x. 

AHA (Animal Health Australia) and PHA (Plant Health Australia) (n.d.) Farm biosecurity action 
planner. AHA and PHA, Canberra. Viewed 26 February 2024, 
https://www.farmbiosecurity.com.au/toolkit/planner/. 

Albus WL and Knighton RE (1998) Water quality in a sand plain after conversion from dryland to 
irrigation: tillage and cropping systems compared. Soil and Tillage Research 48(3), 195–206. 

Anon. (2024) Government and Plant Industry Cost Sharing Deed in respect of Emergency Plant 
Pest Responses. Viewed 26 February 2024, 
https://www.planthealthaustralia.com.au/biosecurity/emergency-plant-pest-response-
deed/. 

ANZG (2020) Toxicant default guideline values for aquatic ecosystem protection: Metolachlor in 
freshwater. Australian and New Zealand Guidelines for Fresh and Marine Water Quality. 
Viewed 30 September 2024, 
https://www.waterquality.gov.au/sites/default/files/documents/metolachlor_fresh_dgv-
technical-brief_0.pdf. 

APFA (2016) Productivity Commission inquiry into the regulation of Australian marine fisheries and 
aquaculture sectors. Viewed 27 September 2024, Productivity Commission Inquiry (2016) into the Regulation of Australian Marine Fisheries and Aquaculture Sectors. Submission from Australian Prawn Farmers Association (APFA) 


Ash A, Bristow M, Laing A, MacLeod N, Niscioli A, Paini D, Palmer J, Prestwidge D, Stokes C, 
Watson I, Webster T and Yeates S (2018) Agricultural viability: Darwin catchments. A 
technical report to the Australian Government from the CSIRO Northern Australia Water 
Resource Assessment, part of the National Water Infrastructure Development Fund: Water 
Resource Assessments. CSIRO, Australia. 

Atlas of Living Australia (2024) Atlas of Living Australia: occurrence records. 
https://support.ala.org.au/support/home 

Barbieri MV, Peris A, Postigo C, Moya-Garcés A, Monllor-Alcaraz LS, Rambla-Alegre M, Eljarrat E 
and López de Alda M (2021) Evaluation of the occurrence and fate of pesticides in a typical 
Mediterranean delta ecosystem (Ebro River Delta) and risk assessment for aquatic 
organisms. Environmental Pollution 274, 115813. DOI: 10.1016/j.envpol.2020.115813. 

Bayer (2023) Growing cotton in Northern Australia: 2023/24 grower guide. Viewed 26 February 
2024, https://www.crop.bayer.com.au/products/biotechnology-traits/bollgard-3-with-
roundup-ready-flex-cotton#tab-4. 

Bengsen AJ, Gentle MN, Mitchell JL, Pearson HE and Saunders GR (2014) Impacts and 
management of wild pigs Sus scrofa in Australia. Mammal Review 44(2),135–147. 
DOI:10.1111/mam.12011. 


Bradshaw CJA, Hoskins AJ, Haubrock PJ, Cuthbert RN, Diagne C, Leroy B, Andrews L, Page B, Cassey 
P, Sheppard AW and Courchamp F (2021) Detailed assessment of the reported economic 
costs of invasive species in Australia. NeoBiota 67, 511–550. 
DOI:10.3897/neobiota.67.58834. 

Brodie JE and Mitchell AW (2005) Nutrients in Australian tropical rivers: changes with agricultural 
development and implications for receiving environments. Marine and Freshwater Research 
56(3), 279–302. 

Bunn SE and Arthington AH (2002) Basic principles and ecological consequences of altered flow 
regimes for aquatic biodiversity. Environmental Management 30(4), 492-507. 

Burdekin Project Committee (1977) Resources and potential of the Burdekin River Basin, 
Queensland. Main report and 5 volumes of appendices. Australian Government Publishing 
Service, Canberra. 

Burford M, Valdez D, Curwen G, Faggotter S, Ward D and Brien KO (2016) Inundation of saline 
supratidal mudflats provides an important source of carbon and nutrients in an aquatic 
system. Marine Ecology Progress Series 545, 21-33. 

Burford M, Webster I, Revill A, Kenyon R, Whittle M and Curwen G (2012) Controls on 
phytoplankton productivity in a wet–dry tropical estuary. Estuarine, Coastal and Shelf 
Science 113, 141-151. 

Burford MA and Faggotter SJ (2021) Comparing the importance of freshwater flows driving 
primary production in three tropical estuaries. Marine Pollution Bulletin 169, 112565. 

Burford MA, Kenyon RA, Whittle M and Curwen G (2010) Flow and fisheries: River flow impacts on 
estuarine prawns in the Gulf of Carpentaria. FRDC Project 2007/003 Final Report. Griffith 
University and CSIRO Marine and Atmospheric Research, Brisbane. 

Burford MA, Revill AT, Palmer DW, Clementson L, Robson BJ and Webster IT (2011) River 
regulation alters drivers of primary productivity along a tropical river-estuary system. Marine 
and Freshwater Research 62(2), 141-151. DOI: 10.1071/MF10224. 

Burrows DW and Butler B (2007) Determining end-point goals and effective strategies for 
rehabilitation of coastal wetlands: examples from the Burdekin River, north Queensland. In: 
Wilson AL, Dehaan RL, Watts RJ, Page KJ, Bowmer KH and Curtis A (eds) Proceedings of the 
5th Australian Stream Management Conference. Charles Sturt University, Thurgoona, New 
South Wales, 49–54. 

Cantin NE, Negri AP and Willis BL (2007) Photoinhibition from chronic herbicide exposure reduces 
reproductive output of reef-building corals. Marine Ecology Progress Series 344, 81–93. 

Carpenter SR, Caraco NF, Correll DL, Howarth RW, Sharpley AN and Smith VH (1998) Nonpoint 
pollution of surface waters with phosphorus and nitrogen. Ecological Applications 8(3), 559–
568. DOI: 10.2307/2641247. 

Chapman B, Henry R, Wurm P, Bellairs S, Crayn D, Smyth H, Furtado A, Sivapalan S, Ford R and 
Matchett T (2020) A situational analysis for developing a rice industry in Northern Australia. 
Project A.1.1718120, CRC for Developing Northern Australia (CRCNA). Viewed 14 February 


2024, https://crcna.com.au/projects/northern-australia-rice-industry-situational-analysis-
study/ 

Chapman PM, Hayward A and Faithful J (2017) Total suspended solids effects on freshwater lake 
biota other than fish. Bulletin of Environmental Contamination and Toxicology 99(4), 423–
427. DOI: 10.1007/s00128-017-2154-y. 

Christen EW and Ayars J (2001) Subsurface drainage system design and management in irrigated 
agriculture: best management practices for reducing drainage volume and salt load. 
Technical report 38/01. CSIRO Land and Water, Griffith NSW. Hyperlink to 'Subsurface drainage system design and management in irrigated agriculture: best management practices for reducing drainage volume and salt load'
. Viewed 5 August 2024. 

Christian CS, Noakes LC, Perry RA, Slatyer RO, Stewart GA and Traves DM (1954) Survey of the 
Barkly Region, Northern Territory and Queensland, 1947–48. Land Research Series No. 3. 
CSIRO, Melbourne. 

CISS (Centre for Invasive Species Solutions) (2024) Management toolkits. pestSMART website, 
CISS. Viewed 27 February 2024, https://pestsmart.org.au/pest-animals/. 

CISS (Centre for Invasive Species Solutions) (2021) Profiles for Weeds of National Significance. 
Weeds Australia website, CISS. Viewed 13 March 2024, https://weeds.org.au/weeds-
profiles/. 

Clancy TF (2020) Wildlife management program for the magpie goose (Anseranas semipalmata) in 
the Northern Territory of Australia 2020–2030. Northern Territory Department of 
Environment and Natural Resources. Viewed 20 February 2024, 
https://depws.nt.gov.au/programs-and-strategies/magpie-goose-management. 

Close P, Bartolo R, Pettit N, Ward D and Kennard M (2015) Vulnerability and risk assessment of 
northern Australian catchments and biodiversity. Climate Change Adaptation across 
Australia’s Monsoonal North–Northern Monsoon NRM Cluster, Griffith University, Nathan. 

Close P, Dobbs R, Tunbridge D, Speldewinde P, Warfe D, Toussaint S and Davies P (2014) 
Customary and recreational fishing pressure: large-bodied fish assemblages in a tropical, 
intermittent Australian river. Marine and Freshwater Research 65(4), 466-474. 

Cobcroft J, Bell R, Diedrich A, Jerry D and Fitzgerald J (2020) Northern Australia aquaculture 
industry situational analysis: project A.1. 1718119. CRC for Developing Northern Australia 
(CRCNA). Viewed 6 February 2024, https://crcna.com.au/projects/northern-australia-
aquaculture-industry-situational-analysis-study/ 

CRDC (Cotton Research and Development Corporation) (2023) 2023–24 Cotton pest management 
guide. CRDC. Viewed 19 February 2024, https://www.crdc.com.au/publications/cotton-pest-
management-guide. 

Crook DA, Lowe WH, Allendorf FW, Erős T, Finn DS, Gillanders BM, Hadweng WL, Harrod C, 
Hermoso V, Jennings S, Kilada RW, Nagelkerken I, Hansen MM, Page TJ, Riginos C, Fry B and 
Hughes JM (2015) Human effects on ecological connectivity in aquatic ecosystems: 
Integrating scientific approaches to support management and mitigation. Science in the 
Total Environment 534(2015), 52-64. 


CropLife Australia (2021) Resistance management strategies: insecticides, fungicides, herbicides 
2021–2022. CropLife Australia. Viewed 20 March 2024, 
https://www.croplife.org.au/resources/programs/resistance-management-strategies/. 

CSIRO (2013) The environmental management of prawn farming in Queensland – worlds best 
practice. Viewed 27 September 2024, 
https://era.daf.qld.gov.au/id/eprint/2064/2/1._Prawn_farming_environmental_research_1995-2002-sec.pdf 

DAFF (Department of Agriculture, Fisheries and Forestry) (2022a) National biosecurity strategy. 
DAFF, Canberra. Viewed 26 February 2024, https://www.biosecurity.gov.au/about/national-
biosecurity-committee/nbs. 

DAFF (Department of Agriculture, Fisheries and Forestry) (2022b) AQUAPLAN 2022–2027: 
Australia’s national strategic plan for aquatic animal health. DAFF, Canberra. Viewed 26 
February 2024, https://www.agriculture.gov.au/agriculture-land/animal/aquatic/aquaplan. 

DAFF (Department of Agriculture, Fisheries and Forestry) (2023) Permitted live freshwater 
ornamental fish suitable for import. DAFF, Canberra. Viewed 11 March 2024, 
https://www.agriculture.gov.au/biosecurity-trade/policy/legislation/list-of-permitted-live-
freshwater-and-marine-ornamental-fish#daff-page-main. 

DAFF (Department of Agriculture, Fisheries and Forestry) (2024a) Northern Australia quarantine 
strategy (NAQS). DAFF website. Viewed 11 March 2024, 
https://www.agriculture.gov.au/biosecurity-trade/policy/australia/naqs. 

DAFF (Department of Agriculture, Fisheries and Forestry) (2024b) Exporting from Australia. DAFF 
website. Viewed 20 March 2024, https://www.agriculture.gov.au/biosecurity-
trade/export/from-australia. 

Davis A, Thorburn P, Lewis S, Bainbridge Z, Attard S, Milla R and Brodie J (2013) Environmental 
impacts of irrigated sugarcane production: herbicide run-off dynamics from farms and 
associated drainage systems. Agriculture, Ecosystems & Environment 180, 123–135. 

Davis AM, Pearson RG, Brodie JE and Butler B (2017) Review and conceptual models of agricultural 
impacts and water quality in waterways of the Great Barrier Reef catchment area. Marine 
and Freshwater Research 68, 1–19. DOI: 10.1071/MF15301. 

DAWE (Department of Agriculture, Water and the Environment) (2020a) Aquatic animal diseases 
significant to Australia: identification field guide. 5th edn. DAWE, Canberra. Viewed 
10 March 2024, https://www.agriculture.gov.au/agriculture-land/animal/aquatic/guidelines-
and-resources/aquatic_animal_diseases_significant_to_australia_identification_field_guide. 

DAWE (Department of Agriculture, Water and the Environment) (2020b) National policy guidelines 
for the translocation of live aquatic animals. DAWE, Canberra. Viewed 26 February 2024, 
https://www.agriculture.gov.au/agriculture-land/animal/aquatic/biosecurity-plan-
guidelines#national-policy-guidelines-for-the-translocation-of-live-aquatic-animals. 

DCCEEW (2021) Organochlorine pesticides (OCPs) – trade or common use names. Australian 
Government. Viewed 30 September 2024, 
https://www.dcceew.gov.au/environment/protection/publications/ocp-trade-names. 


De’ath G, Fabricius KE, Sweatman H and Puotinen M (2012) The 27-year decline of coral cover on 
the Great Barrier Reef and its causes. Proceedings of the National Academy of Sciences of 
the United States of America 109, 17995–17999. DOI: 10.1073/pnas.1208909109. 

Department of Agriculture and Fisheries Queensland (2013) About biosecurity. Department of 
Agriculture and Fisheries. Queensland. 

Department of Agriculture‚ Water and the Environment (2021) Directory of Important Wetlands in 
Australia. Available online: <https://www.environment.gov.au/water/wetlands/australian-
wetlands-database/directory-important-wetlands>. 

DITT (Department of Industry, Tourism and Trade) (2023) Northern Territory plant health manual. 
Plant Biosecurity Branch, DITT, NT. Viewed 14 February 2024, 
https://nt.gov.au/industry/agriculture/food-crops-plants-and-quarantine/plants-and-
quarantine/introduction. 

Dixon I, Dobbs R, Townsend S, Close P, Ligtermoet E, Dostine P, Duncan R, Kennard M and 
Tunbridge D (2011) Trial of the Framework for the Assessment of River and Wetland Health 
(FARWH) in the wet–dry tropics for the Daly and Fitzroy Rivers, Tropical Rivers and Coastal 
Knowledge (TRaCK) research consortium. Charles Darwin University, Darwin. 

Donovan D (2011) Environmental code of practice for Australian prawn farmers. Viewed 2 June 
2023, Hyperlink to: Environmental Code of Practice for Australian Prawn Farmers
. 

Douglas MM, Bunn SE and Davies PM (2005) River and wetland food webs in Australia’s wet–dry 
tropics: general principles and implications for management. Marine and Freshwater 
Research 56(3), 329-342. 

DPIF (Department of Primary Industry and Fisheries) (2014) Field guide to pests, beneficials, 
diseases and disorders of vegetables in northern Australia. DPIF, Darwin. Viewed 
20 March 2024, 
https://industry.nt.gov.au/__data/assets/pdf_file/0009/227772/vegfieldguide-sml.pdf. 

DSEWPC (Department of Sustainability, Environment, Water, Population and Communities) (2012) 
Threat abatement plan to reduce the impacts on northern Australia’s biodiversity by the five 
listed grasses. DSEWPC, Canberra. Viewed 27 February 2024, 
https://www.dcceew.gov.au/environment/biodiversity/threatened/publications/threat-
abatement-plan-reduce-impacts-northern-australias-biodiversity-five-listed-grasses . 

Duggan M, Connolly R, Whittle M, Curwen G and Burford M (2014) Effects of freshwater flow 
extremes on intertidal biota of a wet-dry tropical estuary. Marine Ecology Progress Series 
502, 11-23. 

Duke NC, Field C, Mackenzie JR, Meynecke J-O and Wood AL (2019) Rainfall and its possible 
hysteresis effect on the proportional cover of tropical tidal-wetland mangroves and 
saltmarsh–saltpans. Marine and Freshwater Research 70(8), 1047-1055. DOI: 
https://doi.org/10.1071/MF18321. 

Dulvy NK, Davidson LN, Kyne PM, Simpfendorfer CA, Harrison LR, Carlson JK and Fordham SV 
(2016) Ghosts of the coast: global extinction risk and conservation of sawfishes. Aquatic 
Conservation: Marine and Freshwater Ecosystems 26(1), 134-153. 


Eastick RJ and Hearnden MN (2006) Potential for weediness of Bt cotton in northern Australia. 
Weed Science, 54(6), 1142–1151. DOI:10.1614/WS-06-077R.1. 

Ebner BC, Millington M, Holmes BJ, Wilson D, Sydes T, Bickel TO, Power T, Hammer M, Lach L, 
Schaffer J, Lymbery A and Morgan DL (2020) Scoping the biosecurity risks and appropriate 
management relating to the freshwater ornamental aquarium trade across northern 
Australia. Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER), James 
Cook University, Cairns. Viewed 20 March 2024, https://era.daf.qld.gov.au/id/eprint/8276/. 

EHP (2013) Operational policy marine prawn aquaculture. Department of Environment and 
Heritage Protection, Queensland Government. Viewed 2 June 2023, Hyperlink to: Operation policy marine prawn aquaculture 


Environment and Invasives Committee (2019) National invasive ant biosecurity plan 2018–2028. 
Australian Government, Canberra. Viewed 23 February 2024, 
https://www.dcceew.gov.au/environment/biodiversity/threatened/publications/tap/invasive-ants.

Finlayson CM, Lowry J, Bellio MG, Nou S, Pidgeon R, Walden D, Humphrey C and Fox G (2006) 
Biodiversity of the wetlands of the Kakadu Region, northern Australia. Aquatic Sciences 
68(3), 374–399. 

Fleming PM, Gunn RH, Reece AM, and McAlpine JR (eds) (1981) Burdekin project ecological study. 
CSIRO and Department of National Development and Energy, Canberra. 

Fojut TL, Palumbo AJ and Tjeerdema RS (2012) Aquatic life water quality criteria derived via the UC 
Davis method: III. Diuron. In: Tjeerdema RS (ed) Aquatic life water quality criteria for 
selected pesticides. Reviews of Environmental Contamination and Toxicology, vol. 216. 
Springer, Boston, USA, 105–141. Viewed 30 September 2024, https://doi.org/10.1007/978-
1-4614-2260-0_3.

Gao J, Wang F, Jiang W, Miao J, Wang P, Zhou Z and Liu D (2020) A full evaluation of chiral 
phenylpyrazole pesticide flufiprole and the metabolites to non-target organism in paddy 
field. Environmental Pollution, 264, 114808. DOI: 10.1016/j.envpol.2020.114808. 

Garnett S (1987) Aerial Surveys of Waders (Aves: Charadriiformes) Along the Coast of North-
eastern Australia. Aus. Wildl. Res. 14, 521-528. 

Gibbs M, Hughes J and Yang A (2024a) River model calibration for the Southern Gulf catchments. A 
technical report from the CSIRO Southern Gulf Water Resource Assessment for the National 
Water Grid. CSIRO, Australia. 

Gibbs M, Hughes J, Yang A, Wang B, Marvanek S and Petheram C (2024b) River model scenario 
analysis for the Southern Gulf catchments. A technical report from the CSIRO Southern Gulf 
Water Resource Assessment for the National Water Grid. CSIRO, Australia. 

Giglio A and Vommaro ML (2022) Dinitroaniline herbicides: a comprehensive review of toxicity and 
side effects on animal non-target organisms. Environmental Science and Pollution Research 
29(51), 76687–76711. DOI: 10.1007/s11356-022-23169-4. 


Grain Storage Extension Project (2024) Stored grain information hub. Stored Grain Project 
website. Viewed 29 February 2024, https://storedgrain.com.au/. 

Grains Research and Development Corporation (2024) WeedSmart website. Viewed 20 March 
2024, https://www.weedsmart.org.au/. 

Hafi A, Arthur T, Medina M, Warnakula C, Addai D and Stenekes N (2023) Cost of established pest 
animals and weeds to Australian agricultural producers. Australian Bureau of Agricultural 
and Resource Economics and Sciences (ABARES), Canberra. Viewed 5 February 2024, 
https://www.agriculture.gov.au/abares/research-topics/biosecurity/biosecurity-
economics/cost-of-established-pest-animals-and-weeds-to-australian-agricultural-producers 

Hart BT, Lake PS, Webb JA and Grace MR (2003) Ecological risk to aquatic systems from salinity 
increases. Australian Journal of Botany 51(6), 689–702. 

Hassaan MA and El Nemr A (2020) Pesticides pollution: classifications, human health impact, 
extraction and treatment techniques. Egyptian Journal of Aquatic Research 46(3), 207–220. 
DOI: 10.1016/j.ejar.2020.08.007. 

Hennecke BR (2012) Assessing new Weeds of National Significance candidates. Proceedings of the 
18th Australasian Weeds Conference. Weed Society of Victoria Inc., Melbourne. Viewed 20 
March 2024, https://caws.org.nz/18th-australasian-weeds-conference-2012/. 

Hunt R, Jardine T, Hamilton S and Bunn S (2012) Temporal and spatial variation in ecosystem 
metabolism and food web carbon transfer in a wet-dry tropical river. Freshwater Biology 
57(3), 435-450. DOI: 10.1111/j.1365-2427.2011.02708.x. 

Irvin S, Coman G, Musson D, Doshi A and Stokes C (2018) Aquaculture viability. A technical report 
to the Australian Government from the CSIRO Northern Australia Water Resource 
Assessment, part of the National Water Infrastructure Development Fund: Water Resource 
Assessments. CSIRO, Australia. Viewed 14 February 2024, 
https://publications.csiro.au/publications/publication/PIcsiro:EP181756. 

Irvin S, Coman G, Musson D, Doshi A, Stokes C (2018). Aquaculture viability. A technical report to 
the Australian Government from the CSIRO Northern Australia Water Resource Assessment, 
part of the National Water Infrastructure Development Fund: Water Resource Assessments. 
Australia: CSIRO; 2018. csiro:EP181756. https://doi.org/10.25919/5b86ed759d698 

Jardine TD, Bond NR, Burford MA, Kennard MJ, Ward DP, Bayliss P, Davies PM, Douglas MM, 
Hamilton SK, Melack JM, Naiman RJ, Pettit NE, Pusey BJ, Warfe DM and Bunn SE (2015) Does 
flood rhythm drive ecosystem responses in tropical riverscapes? Ecology 96(3), 684-692. 

Jellyman D, Gehrke PC and Harris JH (2016) Australasian freshwater fisheries. In: Craig JF (ed.), 
Freshwater Fisheries Ecology. John Wiley & Sons, Ltd., Oxford. 

Jolly I, Taylor A, Rassam D, Knight J, Davies P and Harrington G (2013) Surface water — 
groundwater connectivity. . A technical report to the Australian Government from the CSIRO 
Flinders and Gilbert Agricultural Resource Assessment, part of the North Queensland 
Irrigated Agriculture Strategy. CSIRO Water for a Healthy Country and Sustainable 
Agriculture flagships, Australia. 


Junk W, Bayley P and Sparks R (1989) The flood pulse concept in river-floodplain systems. In: 
Dodge D (ed.), Proceedings of the International Large River Symposium. Canadian special 
publication of Fisheries and Aquatic Sciences. 

Kaur R, Mavi GK, Raghav S and Khan I (2019) Pesticides classification and its impact on 
environment. International Journal of Current Microbiology and Applied Science 8(3), 1889–
1897. 

Kearney M, Phillips BL, Tracy CR, Christian KA, Betts G and Porter WP (2008) Modelling species 
distributions without using species distributions: the cane toad in Australia under current 
and future climates. Ecography 31(4), 423–434. DOI:10.1111/j.0906-7590.2008.05457.x. 

Kennard MJ, Mackay SJ, Pusey BJ, Olden JD and Marsh N (2010) Quantifying uncertainty in 
estimation of hydrologic metrics for ecohydrological studies. River Res. Applic. 26, 137-156. 

Kingsford R and Norman F (2002) Australian waterbirds—products of the continent’s ecology. Emu 
102(1), 47-69. 

Kremser U and Schnug E (2002) Impact of fertilizers on aquatic ecosystems and protection of 
water bodies from mineral nutrients. Landbauforsch Völkenrode 52(2), 81–90. 

Kroon FJ, Thorburn P, Schaffelke B and Whitten S (2016) Towards protecting the Great Barrier Reef 
from land-based pollution. Global Change Biology 22, 1985–2002. DOI: 10.1111/gcb.13262. 

Kutt A, Felderhof L, VanDerWal J, Stone P and Perkins G (2009) Chapter 4. Terrestrial ecosystems 
of northern Australia. Northern Australia Land and Water Science Review, October 2009. 

Landos M, Calogeras C, Ruscoe J-A, Hayward S and Ruscoe J (2019) National biosecurity plan 
guidelines for Australian barramundi Farms. Department of Agriculture, Canberra. Viewed 20 
February 2024, https://www.agriculture.gov.au/agriculture-
land/animal/aquatic/biosecurity-plan-guidelines#barramundi-farms. 

Le DP, Tran TT, Gregson A and Jackson R (2020) TEF1 sequence-based diversity of Fusarium species 
recovered from collar rot diseased cotton seedlings in New South Wales, Australia. 
Australasian Plant Pathology 49(3), 277–284. Hyperlink to: TEF1 sequence-based diversity of Fusarium species recovered from collar rot diseased cotton seedlings in New South Wales, Australia
. 

Leahy SM and Robins JB (2021) River flows affect the growth of a tropical finfish in the wet-dry 
rivers of northern Australia, with implications for water resource development. 
Hydrobiologia 848(18), 4311-4333. 

Lear KO, Gleiss AC, Whitty JM, Fazeldean T, Albert J, Green N, Ebner BC, Thorburn DC, Beatty SJ 
and Morgan DL (2019) Recruitment of a critically endangered sawfish into a riverine nursery 
depends on natural flow regimes. Scientific Reports 9(1), 17071. 

Lear KO, Morgan DL, Whitty JM, Beatty SJ and Gleiss AC (2021) Wet season flood magnitude drives 
resilience to dry season drought of a euryhaline elasmobranch in a dry-land river. Science of 
The Total Environment 750, 142234. 

Leigh C and Sheldon F (2008) Hydrological changes and ecological impacts associated with water 
resource development in large floodplain rivers in the Australian tropics. River Res. Applic. 
24(2008), 1251-1270. 


Lewis SE, Brodie JE, Bainbridge ZT, Rohde KW, Davis AM, Masters BL, Maughan M, Devlin MJ, 
Mueller JF and Schaffelke B (2009) Herbicides: a new threat to the Great Barrier Reef. 
Environmental Pollution 157, 2470–2484. DOI: 10.1016/j.envpol.2009.03.006. 

Lowe V, Frid CLJ, Venarsky M and Burford MA (2022) Responses of a macrobenthic community to 
seasonal freshwater flow in a wet-dry tropical estuary. Estuarine, Coastal and Shelf Science 
265, 107736. DOI: https://doi.org/10.1016/j.ecss.2021.107736. 

Mainstone CP and Parr W (2002) Phosphorus in rivers — ecology and management. Science of the 
Total Environment 282–283, 25–47. DOI: 10.1016/S0048-9697(01)00937-8. 

Makinson RO, Pegg GS and Carnegie AJ (2020) Myrtle rust in Australia – a national action plan. 
Australian Plant Biosecurity Science Foundation, Canberra. Viewed 11 March 2024, 
https://www.apbsf.org.au/myrtle-rust/. 

Marchant S and Higgins P (1990) Handbook of Australian, New Zealand and Antarctic Birds. 
Volume 1, Ratites to ducks. Oxford University Press, Melbourne. 

Marsh N, Sheldon F, Wettin P, Taylor C and Barma D (2012) Guidance on ecological responses and 
hydrological modelling for low-flow water planning, March 2012. The National Water 
Commission, Canberra. 

Martens DA (2005) Denitrification. In: Hillel D and Hatfield JL (eds) Encyclopedia of soils in the 
environment (Vol. 3). Elsevier, 378–382. DOI: 10.1016/B0-12-348530-4/00138-7. 

McGinness HM (2016) Waterbird responses to flooding, stressors and threats. A report prepared 
for the Murray-Darling Freshwater Research Centre as part of the Environmental Water 
Knowledge and Research Project. CSIRO, Canberra, Australia. 

McJannet D, Marvanek S, Kinsey-Henderson A, Petheram C and Wallace J (2014) Persistence of in-
stream waterholes in ephemeral rivers of tropical northern Australia and potential impacts 
of climate change. Marine and Freshwater Research 65(12), 1131-1144. DOI: 
10.1071/MF14035. 

McJannet D, Yang A and Seo L (2023) Climate data characterisation for hydrological and 
agricultural scenario modelling across the Victoria, Roper and Southern Gulf catchments. A 
technical report from the CSIRO Victoria River and Southern Gulf Water Resource 
Assessments for the National Water Grid. CSIRO, Australia. 

McMahon TA and Finlayson BL (2003) Droughts and anti-droughts: the low flow hydrology of 
Australian rivers. Freshwater Biology 48(2003), 1147–1160. 

Merrin L, Stratford D, Kenyon R, Pritchard J, Linke S, Ponce Reyes R, Buckworth R, Castellazzi P, 
Costin B, Deng R, Gannon R, Gao S, Gilbey S, Lachish S, McGinness H and Waltham N (2024) 
Ecological assets of the Southern Gulf catchments to inform water resource assessments. A 
technical report from the CSIRO Southern Gulf Water Resource Assessment for the National 
Water Grid. CSIRO, Australia. 

Miller JL, Schmidt TS, Van Metre PC, Mahler BJ, Sandstrom MW, Nowell LH, Carlisle DM and 
Moran PW (2020) Common insecticide disrupts aquatic communities: A mesocosm-to-field 
ecological risk assessment of fipronil and its degradates in U.S. streams. Science Advances 
6(43), eabc1299. DOI: 10.1126/sciadv.abc1299. 


Mitchell A, Reghenzani J, Faithful J, Furnas M and Brodie J (2009) Relationships between land use 
and nutrient concentrations in streams draining a wet-tropics catchment in northern 
Australia. Marine and Freshwater Research 60, 1097–1108. DOI: 10.1071/MF08330. 

Mitsch WJ, Bernal B and Hernandez ME (2015) Ecosystem services of wetlands. Taylor & Francis. 

Mohanty SS and Jena HM (2019) A systemic assessment of the environmental impacts and 
remediation strategies for chloroacetanilide herbicides. Journal of Water Process 
Engineering 31, 100860. DOI: 10.1016/j.jwpe.2019.100860. 

Moore GA, Munday C and Barua P (2022) Environmental weed risk assessment protocol for 
growing non-indigenous plants in the Western Australian rangelands. Department of Primary 
Industries and Regional Development, Perth. Viewed 20 March 2024, 
https://library.dpird.wa.gov.au/bulletins/279/. 

Morgan D, Whitty J, Allen M, Ebner B, Keleher J, Gleiss A and Beatty S (2016) Wheatstone 
Environmental Offsets-Barriers to sawfish migrations. A report for Chevron Australia and the 
Western Austalian Marine Science Institution. Freshwater Fish Group & Fish Health Unit, 
Centre for Fish & Fisheries Research, Murdoch University. 

Morgan DL, Somaweera R, Gleiss AC, Beatty SJ and Whitty JM (2017) An upstream migration 
fought with danger: freshwater sawfish fending off sharks and crocodiles. Ecology 98(5), 
1465-1467. 

Mosley LM and Fleming N (2010) Pollutant loads returned to the Lower Murray River from flood-
irrigated agriculture. Water, Air, and Soil Pollution 211(1–4), 475–487. DOI: 10.1007/s11270-
009-0316-1. 

Motson K, Mishra A and Waltham N (2024) A review of water quality studies relevant to northern 
Australia. A technical report from the CSIRO Victoria and Southern Gulf Water Resource 
Assessments for the National Water Grid. CSIRO, Australia. 

Moulden JH, Yeates SJ, Strickland GR and Plunkett GM (2006) Developing an environmentally 
responsible irrigation system for cotton in the Ord River Irrigation Area. Proceedings of 
ANCID 2006, 16–19 October, Darwin, NT. The Australian National Committee on Irrigation 
and Drainage, Sydney. 

myBMP (2024) myBMP website. Viewed 26 February 2024, https://www.mybmp.com.au/. 

Naccarato A, Vommaro ML, Amico D, Sprovieri F, Pirrone N, Tagarelli A and Giglio A (2023) Triazine 
herbicide and NPK fertilizer exposure: accumulation of heavy metals and rare earth 
elements, effects on cuticle melanization, and immunocompetence in the model species 
Tenebrio molitor. Toxics 11(6), 499. 

Naughton JM, O’Dea K and Sinclair AJ (1986) Animal foods in traditional Australian aboriginal diets: 
polyunsaturated and low in fat. Lipids 21(11), 684-690. 

Nielsen D, Merrin L, Pollino C, Karim F, Stratford D and O’Sullivan J (2020) Climate change and dam 
development: Effects on wetland connectivity and ecological habitat in tropical wetlands. 
Ecohydrology 2020, 13pgs. DOI: 10.1002/eco.2228. 


Nielsen DL, Cook RA, Ning N, Gawne B and Petrie R (2015) Carbon and nutrient subsidies to a 
lowland river following floodplain inundation. Marine and Freshwater Research 67(9), 1302-
1312. 

Nilsson C and Berggren K (2000) Alterations of riparian ecosystems caused by river regulation. 
BioScience 50(9), 783-792. 

Novak P, Bayliss P, Crook DA, Garcia EA, Pusey BJ and MM D (2017) Do upstream migrating, 
juvenile amphidromous shrimps, provide a marine subsidy to river ecosystems? Freshwater 
Biology 62(5), 880-893. DOI: 10.1111/fwb.12907. 

NT Farmers (2022) Northern Australia broadacre cropping manual. Northern Territory Farmers 
Association. Viewed 26 February 2024, https://ntfarmers.org.au/wp-
content/uploads/2023/01/NA-Broadacre-Cropping-Manual-Final-Digital.pdf. 

NT Government (2016) Northern Territory biosecurity strategy 2016–2026. NT Government. 
Viewed 30 January 2024, https://industry.nt.gov.au/industries/primary-
industry/agriculture/agricultural-developments/nt-biosecurity-strategy-2016-2026. 

NT Government (2021) Katherine Regional Weeds Strategy 2021–2026. NT Government 
Department of Environment, Parks and Water Security. Viewed 2 January 2024, Hyperlink to: Katherine Regional Weeds Strategy 2021-2026
. 

NT Government (2024a) Plant diseases and pests. NT.GOV.AU website. Viewed 27 February 2024, 
https://nt.gov.au/industry/agriculture/food-crops-plants-and-quarantine/plant-diseases-
and-pests/pests-and-diseases. 

NT Government (2024b) Cucumber green mottle mosaic virus (CGMMV). NT.GOV.AU website. 
Viewed 19 February 2024, https://nt.gov.au/industry/agriculture/food-crops-plants-and-
quarantine/cucumber-green-mottle-mosaic-virus/cucumber-green-mottle-mosaic-virus. 

NT Government (2024c) Using chemicals responsibly. NT.GOV.AU website. Viewed 26 February 
2024, https://nt.gov.au/industry/agriculture/farm-management/using-chemicals-
responsibly/managing-chemical-residues. 

NT Government (2024d) Feral animals. NT.GOV.AU website. Viewed 27 February 2024, 
https://nt.gov.au/environment/animals/feral-animals. 

Nye ER, Dickman CR and Kingsford RT (2007) A wild goose chase-temporal and spatial variation in 
the distribution of the Magpie Goose (Anseranas semipalmata) in Australia. Emu 107(1), 28-
37. DOI: 10.1071/MU05012. 

Office of the Gene Technology Regulator (2024) The Biology of Gossypium hirsutum L. and 
Gossypium barbadense L. (cotton). Viewed 2 September 2024, 
https://www.ogtr.gov.au/resources/collections/biology-documents 

Olden JD and Poff L (2003) Redundancy and the choice of hydrologic indices for characterizing 
streamflow regimes. River Res. Applic. 19(2003), 101-121. 

Outbreak (2023a) Banana freckle (Phyllosticta cavendishii). Outbreak Animal and Plant Pests and 
Diseases website. Viewed 20 March 2024, https://www.outbreak.gov.au/current-
outbreaks/banana-freckle. 


Outbreak (2023b) Red imported fire ant (Solenopsis invicta), Outbreak Animal and Plant Pests and 
Diseases website. Viewed 10 March 2024, https://www.outbreak.gov.au/current-
outbreaks/red-imported-fire-ant. 

Outbreak (2024) Respond to, prevent and prepare for animal and plant pest and disease 
outbreaks. Outbreak Animal and Plant Pests and Diseases website. Viewed 23 February 
2024, https://www.outbreak.gov.au/. 

Palviainen M, Peltomaa E, Laurén A, Kinnunen N, Ojala A, Berninger F, Zhu X and Pumpanen J 
(2022) Water quality and the biodegradability of dissolved organic carbon in drained boreal 
peatland under different forest harvesting intensities. Science of the Total Environment 806, 
150919. DOI: 10.1016/j.scitotenv.2021.150919. 

Pelicice FM, Pompeu PS and Agostinho AA (2015) Large reservoirs as ecological barriers to 
downstream movements of Neotropical migratory fish. Fish and Fisheries 2015(16), 697-715. 

Perna C (2003) Fish habitat assessment and rehabilitation in the Burdekin Delta distributary 
streams. Report 03/22. Australian Centre for Tropical Freshwater Research, James Cook 
University, Townsville. 

Perna C (2004) Impacts of agriculture and restoration of the habitat values, water quality and fish 
assemblages of a tropical floodplain. MSc Thesis, James Cook University, Townsville. 

Perry RA, Sleeman JR, Twidale CR, Prichard CE, Slatyer RO, Lazarides M and Collins FH (1964) 
General report on lands of the Leichhardt–Gilbert area, Queensland, 1953–54. In Land 
Research Series No. 11. CSIRO, Melbourne. 

Petheram C, McMahon TA and Peel MC (2008) Flow characteristics of rivers in northern Australia: 
Implications for development. Journal of Hydrology 357(1), 93-111. DOI: 
https://doi.org/10.1016/j.jhydrol.2008.05.008. 

Petheram C, Rustomji P, Chiew FHS and Vleeshouwer J (2012) Rainfall–runoff modelling in 
northern Australia: A guide to modelling strategies in the tropics. Journal of Hydrology 462-
463, 28-41. DOI: https://doi.org/10.1016/j.jhydrol.2011.12.046. 

Petheram C, Walker G, Grayson R, Thierfelder T and Zhang L (2002) Towards a framework for 
predicting impacts of land-use on recharge: 1. A review of recharge studies in Australia. 
Australian Journal of Soil Research 40(3), 397–417. DOI: 10.1071/SR00057. 

PHA (Plant Health Australia) (2020) Fall armyworm continuity plan for the Australian grains 
industry. Version 1, November 2020. PHA, Canberra. Viewed 2 January 2024, 
https://www.planthealthaustralia.com.au/fall-armyworm/. 

PHA (Plant Health Australia) (2021) Exotic pest identification and surveillance guide for tropical 
horticulture. Version 1.0, February 2021. PHA, Canberra. Viewed 20 March 2024, 
https://www.planthealthaustralia.com.au/biosecurity/surveillance/exotic-pest-
identification-and-surveillance-guide-for-tropical-horticulture/. 

PHA (Plant Health Australia) (2022) PLANTPLAN: Australian emergency plant pest response plan. 
PHA, Canberra. Viewed 26 February 2024, 
https://www.planthealthaustralia.com.au/biosecurity/incursion-management/plantplan/. 


PHA (Plant Health Australia) (2024a) Industries. PHA website. Viewed 26 February 2024, 
https://www.planthealthaustralia.com.au/industries/. 

PHA (Plant Health Australia) (2024b) Protecting grains from diseases, pests and weeds. Grains 
farm biosecurity program website. Viewed 28 March 2024, 
https://grainsbiosecurity.com.au/. 

Phillips NM, Chaplin JA, Morgan DL and Peverell SC (2011) Population genetic structure and 
genetic diversity of three critically endangered Pristis sawfishes in Australian waters. Marine 
Biology 158(4), 903-915. DOI: 10.1007/s00227-010-1617-z. 

PIRSA (South Australian Department of Primary Industries and Regions ) (2024) Plant quarantine 
standard South Australia. Version 17.4. PIRSA, Adelaide. Viewed 26 February 2024, 
https://pir.sa.gov.au/biosecurity/plant_health/plant_quarantine_standard_and_updated_conditions. 

Plagányi É, Kenyon R, Blamey L, Robins J, Burford M, Pillans R, Hutton T, Hughes J, Kim S and Deng 
RA (2024) Integrated assessment of river development on downstream marine fisheries and 
ecosystems. Nature Sustainability 7(1), 31-44. 

Poff NL and Zimmerman JK (2010) Ecological responses to altered flow regimes: a literature review 
to inform the science and management of environmental flows. Freshwater Biology 55(1), 
194-205. 

Poff NL, Olden JD, Merritt DM and Pepin DM (2007) Homogenization of regional river dynamics by 
dams and global biodiversity implications. PNAS 104(4), 5732-5737. 

Poiani A (2006) Effects of floods on distribution and reproduction of aquatic birds. Advances in 
Ecological Research, Vol 39 39, 63-83. DOI: 10.1016/s0065-2504(06)39004-6. 

Pollino C, Barber E, Buckworth R, Cadiegues M, Deng R, Ebner B, Kenyon R, Liedloff A, Merrin L, 
Moeseneder C, Morgan D, Nielsen D, O’Sullivan J, Ponce Reyes R, Robson B, Stratford D, 
Stewart-Koster B and Turschwell M (2018) Synthesis of knowledge to support the 
assessment of impacts of water resource development to ecological assets in northern 
Australia: asset analysis. A technical report to the Australian Government from the CSIRO 
Northern Australia Water Resource Assessment, part of the National Water Infrastructure 
Development Fund: Water Resource Assessments. CSIRO, Canberra. 

Ponce Reyes R, Stratford D, Linke S, Merrin L, Kenyon R, Buckworth R, Deng RA, Hughes J, 
McGinness H, Pritchard J, Seo L and Waltham N (2024) Assessment of the potential 
ecological outcomes of water resource development in the Southern Gulf catchments. A 
technical report from the CSIRO Southern Gulf Water Resource Assessment for the National 
Water Grid. CSIRO, Australia. 

Pyšek P, Hulme PE, Simberloff D, Bacher S, Blackburn TM, Carlton JT, Dawson W, Essl F, Foxcroft 
LC, Genovesi P, Jeschke JM, Kühn I, Liebhold AM, Mandrak NE, Meyerson LA, Pauchard A, 
Pergl J, Roy HE, Seebens H, van Kleunen M, Vilà M, Wingfield MJ and Richardson DM (2020) 
Scientists’ warning on invasive alien species. Biological Reviews 2020(95), 1511–1534. DOI: 
10.1111/brv.12627. 


Queensland Government (2018) Controlling invasive animals. Business Queensland website. 
Viewed 29 February 2024, https://www.business.qld.gov.au/industries/farms-fishing-
forestry/agriculture/biosecurity/animals/invasive/control. 

Queensland Government (2019) Cucumber green mottle mosaic virus. Business Queensland 
website. Viewed 27 February 2024, https://www.business.qld.gov.au/industries/farms-
fishing-forestry/agriculture/biosecurity/plants/priority-pest-disease/cucumber-green-
mottle-mosaic-virus. 

Queensland Government (2022) Priority plant pests and diseases. Business Queensland. Viewed 
27 February 2024, https://www.business.qld.gov.au/industries/farms-fishing-
forestry/agriculture/biosecurity/plants/priority-pest-disease. 

Queensland Government (2023a) Clearing codes. Viewed 4 July 2024, 
https://www.qld.gov.au/environment/land/management/vegetation/clearing-
approvals/codes/choose#:~:text=The%20most%20common%20example%20of,to%20clear%
20in%20these%20areas. 

Queensland Government (2023b) Your legal obligation for invasive freshwater animals. 
Queensland Department of Agriculture and Fisheries. Viewed 4 July 2024, 
https://www.daf.qld.gov.au/__data/assets/pdf_file/0008/1398842/prohibited-restricted-
invasive-fish.pdf . 

Queensland Government (2023d) Restrictions on moving plant material, soil and related 
equipment. Business Queensland website. Viewed 28 March 2024, 
https://www.business.qld.gov.au/industries/farms-fishing-
forestry/agriculture/biosecurity/plants/moving/restrictions. 

Queensland Government (2023e) Using chemicals safely and effectively. Business Queensland 
website. Viewed 29 February 2024, https://www.business.qld.gov.au/industries/farms-
fishing-forestry/agriculture/sustainable/chemical/use/safety. 

Queensland Government (2023c) Biosecurity Manual: Version 21.0. Business Queensland website. 
Viewed 26 February 2024, https://www.business.qld.gov.au/industries/farms-fishing-
forestry/agriculture/biosecurity/plants/moving/restrictions/into-qld. 

Queensland Government (2024a) Biosecurity. Business Queensland website. Viewed 29 February 
2024, https://www.business.qld.gov.au/industries/farms-fishing-
forestry/agriculture/biosecurity. 

Queensland Government (2024b) Disease in aquaculture farms. Business Queensland website. 
Viewed 28 March 2024, https://www.business.qld.gov.au/industries/farms-fishing-
forestry/fisheries/aquaculture/disease. 

Rad SM, Ray AK and Barghi S (2022) Water pollution and agriculture pesticide. Clean Technologies 
4(4), 1088–1102. 

Read M, Wright B and Enoch C (2004) Crocodiles in Queensland- An Overview. 
Crocodiles:Proceedings of the 17th Working Meeting of the Crocodile Specialist Group, 
IUCN- The World Conservation Union. Gland, Switzerland and Cambridge UK. 


Records RM, Wohl E and Arabi M (2016) Phosphorus in the river corridor. Earth-Science Reviews 
158, 65–88. DOI: 10.1016/j.earscirev.2016.04.010. 

Richter BD, Baumgartner JV, Powell J and Braun DP (1996) A method for assessing hydrologic 
alteration within ecosystems. Conservation biology 10(4), 1163-1174. 

Robins JB, Northrop AR, Grubert M and Buckworth RC (2020) Understanding environmental and 
fisheries factors causing fluctuations in mud crab and blue swimmer crab fisheries in 
northern Australia to inform harvest strategies. Department of Agriculture and Fisheries. 
Brisbane. 

Rogers DJ, Reid RE, Rogers JJ and Addison SJ (2007) Prediction of the naturalisation potential and 
weediness risk of transgenic cotton in Australia. Agriculture, Ecosystems & Environment, 
119, 177–189. DOI:10.1016/j.agee.2006.07.007. 

Sánchez-Bayo F and Hyne RV (2014) Detection and analysis of neonicotinoids in river waters – 
development of a passive sampler for three commonly used insecticides. Chemosphere 99, 
143–151. DOI: 10.1016/j.chemosphere.2013.10.051. 

Schmutz S and Sendzimir J (eds) (2018) Riverine Ecosystem Management Science for Governing 
Towards a Sustainable Future. Springer Open. 

Seafarms (2016) Seafarms group – project sea dragon. Viewed 27 September 2024, 
https://seafarms.com.au/project-sea-dragon/ 

Setterfield SA, Rossiter-Rachor NA, Douglas MM, Wainger L, Petty AM, Barrow P, Shepherd IJ and 
Ferdinands KB (2013) Adding fuel to the fire: the impacts of non-native grass invasion on fire 
management at a regional scale. PLoS ONE, 8(5), e59144. 
DOI:10.1371/journal.pone.0059144. 

SGNRM (Southern Gulf NRM) and NWQROC (North West Queensland Regional Organisation of 
Councils) (2022) North West Queensland Regional Biosecurity Plan 2022–2027. SGNRM and 
NWQROC. Viewed 2 January 2024, https://www.nwqroc.com.au/news/regional-biosecurity-
plan-a-first-for-north-west-queensland. 

Short AD (2020) Australian coastal systems: beaches, barriers and sediment compartments. 
Springer, Switzerland. 

Skhiri A and Dechmi F (2012) Impact of sprinkler irrigation management on the Del Reguero river 
(Spain) II: phosphorus mass balance. Agricultural Water Management 103, 130–139. 
DOI: 10.1016/j.agwat.2011.11.004. 

Staples D and Vance D (1986) Emigration of juvenile banana prawns Penaeus merguiensis from a 
mangrove estuary and recruitment to offshore areas in the wet-dry tropics of the Gulf of 
Carpentaria, Australia. Marine Ecology Progress Series 27(239), 52. 

Stevens MM, Burdett AS, Mudford EM, Helliwell S and Doran G (2011) The acute toxicity of fipronil 
to two non-target invertebrates associated with mosquito breeding sites in Australia. Acta 
Tropica 117(2), 125–130. DOI: 10.1016/j.actatropica.2010.11.002. 

Stratford D, Merrin L, Linke S, Kenyon R, Ponce Reyes R, Buckworth R, Deng RA, McGinness H, 
Pritchard J, Seo L and Waltham N (2024) Assessment of the potential ecological outcomes of 


water resource development in the Roper catchment. A technical report from the CSIRO 
Roper River Water Resource Assessment for the National Water Grid. CSIRO, Australia. 

Subcommittee on Domestic Quarantine and Market Access (2024) Moving plant goods interstate. 
Australian Interstate Quarantine website. Viewed 28 March 2024, 
https://interstatequarantine.org.au/producers/moving-plant-goods/ 

Tait J (2005) Identifying existing wetland management practices and needs on southern gulf 
pastoral properties. Report to WWF – Australia and Southern Gulf Catchments. 

Tait J and Perna C (2001) Fish habitat management challenges on an intensively developed tropical 
floodplain: Burdekin River North Queensland. RipRap 19, 14–21. 

Tanji KK and Kielen NC (2002) Agricultural water management in arid and semi-arid areas. 
Irrigation and drainage paper 61. Food and Agriculture Organization of the United Nations, 
Rome. 

Thorburn PJ, Wilkinson SN and Silburn DM (2013) Water quality in agricultural lands draining to 
the Great Barrier Reef: a review of causes, management and priorities. Agriculture, 
Ecosystems and Environment 180, 4–20. DOI: 10.1016/j.agee.2013.07.006. 

Tockner K, Pusch M, Borchardt D and Lorang MS (2010) Multiple stressors in coupled river–
floodplain ecosystems. Freshwater Biology 55, 135-151. 

Traill LW, Bradshaw CJA, Delean S and Brook BW (2010) Wetland conservation and sustainable use 
under global change: a tropical Australian case study using magpie geese. Ecography 33(5), 
818-825. DOI: 10.1111/j.1600-0587.2009.06205.x. 

Traill LW, Bradshaw CJA, Field HE and Brook BW (2009a) Climate Change Enhances the Potential 
Impact of Infectious Disease and Harvest on Tropical Waterfowl. Biotropica 41(4), 414-423. 
DOI: 10.1111/j.1744-7429.2009.00508.x. 

Traill LW, Whitehead PJ and Brook BW (2009b) How will climate change affect plant-herbivore 
interactions? A tropical waterbird case study. Emu 109(2), 126-134. DOI: 10.1071/MU09003. 

US EPA (2024) Causal Analysis/Diagnosis Decision Information System (CADDIS): pH. United States 
Environmental Protection Agency. Viewed 30 September 2024, 
https://www.epa.gov/caddis/ph. 

van Dam RA, Bartolo R and Bayliss P (2008a) Chapter 2: Identification of ecological assets, 
pressures and threats. In: Bartolo R, Bayliss P and Van Dam RA (eds), Ecological risk 
assessment for Australia’s northern tropical rivers. Land and Water Australia, Canberra. 

van Dam RA, Bartolo R and Bayliss P (2008a) Identification of ecological assets, pressures and 
threats. Environmental Research Institute of the Supervising Scientist: Darwin, Australia, 14-
161. 

Venarsky MP, Lowe V, Frid CLJ and Burford MA (2022) Flow regimes among rivers influences 
benthic biota biodiversity, but not abundance or biomass, in intertidal mudflats and 
sandflats in wet-dry tropical estuaries. Estuarine, Coastal and Shelf Science 271, 107858. 
DOI: https://doi.org/10.1016/j.ecss.2022.107858. 

Waltham N, Burrows D, Butler B, Wallace J, Thomas C, James C and Brodie J (2013) Waterhole 
ecology in the Flinders and Gilbert catchments. A technical report to the Australian 


Government from the CSIRO Flinders and Gilbert Agricultural Resource Assessment, part of 
the North Queensland Irrigated Agriculture Strategy. CSIRO Water for a Healthy Country and 
Sustainable Agriculture flagships, Australia. 

Wang YYL, Xiong J, Ohore OE, Cai Y-E, Fan H, Sanganyado E, Li P, You J, Liu W and Wang Z (2022) 
Deriving freshwater guideline values for neonicotinoid insecticides: Implications for water 
quality guidelines and ecological risk assessment. Science of the Total Environment 828, 
154569. DOI: 10.1016/j.scitotenv.2022.154569. 

Ward JV and Stanford J (1995) Ecological connectivity in alluvial river ecosystems and its disruption 
by flow regulation. Regulated rivers: research & management 11(1), 105-119. 

Ward M, Carwardine J, Yong CJ, Watson JEM, Silcock J, Taylor GS, Lintermans M, Gillespie GR, 
Garnett ST, Woinarski J, Tingley R, Fensham RJ, Hoskin CJ, Hines HB, Roberts JD, Kennard MJ, 
Harvey MS, Chapple DG and Reside AE (2021) A national‐scale dataset for threats impacting 
Australia’s imperilled flora and fauna. Ecology and Evolution 11(17), 11749–61. 
DOI:10.1002/ece3.7920. 

Waterhouse J, Brodie J, Lewis S and Mitchell A (2012) Quantifying the sources of pollutants in the 
Great Barrier Reef catchments and the relative risk to reef ecosystems. Marine Pollution 
Bulletin 65, 394–406. DOI: 10.1016/j.marpolbul.2011.09.031. 

Weston DP and Lydy MJ (2014) Toxicity of the insecticide fipronil and its degradates to benthic 
macroinvertebrates of urban streams. Environmental Science & Technology 48(2), 1290. 
DOI: 10.1021/es4045874. 

Yang A, Petheram C, Marvanek S, Baynes F, Rogers L, Ponce Reyes R, Zund P, Seo L, Hughes J, 
Gibbs M, Wilson PR, Philip S and Barber M (2024) Assessment of surface water storage 
options in the Victoria and Southern Gulf catchments. A technical report from the CSIRO 
Victoria River and Southern Gulf Water Resource Assessments for the National Water Grid. 
CSIRO Australia. 

Yeates S (2016) Comparison of delayed release N fertiliser options for cotton on clay soils with 
urea; yield, N fertiliser uptake and N losses in runoff – Burdekin 2013–2015. Cotton Research 
and Development Project: CSP1302. 

Zhao J and Chen B (2016) Species sensitivity distribution for chlorpyrifos to aquatic organisms: 
Model choice and sample size. Ecotoxicology and Environmental Safety 125, 161–169. DOI: 
10.1016/j.ecoenv.2015.11.039. 


Appendices 

 

 

Lawn Hill Gorge on Lawn Hill Creek 
is a popular tourist attraction 

Photo: Manfred Gottschalk – Alamy stock photo 



Assessment products 

 
More information about the Southern Gulf Water Resource Assessment can be found at 
https://www.csiro.au/southerngulf. The website provides readers with a communications suite 
including factsheets, multimedia content, FAQs, reports and links to other related sites, 
particularly about other research in northern Australia. 

In order to meet the requirements specified in the contracted ‘Timetable for the Services’, the 
Assessment provided the following key deliverables: 

• Technical reports present scientific work at a level of detail sufficient for technical and scientific 
experts to reproduce the work. Each of the activities of the Assessment has at least one 
corresponding technical report. 
• The catchment report (this report) synthesises key material from the technical reports, providing 
well-informed but non-scientific readers with the information required to make decisions about 
the opportunities, costs and benefits associated with water resource development. 
• A summary report is provided for a general public audience. 
• A factsheet provides key findings for a general public audience. 


This appendix lists all such deliverables, plus those jointly delivered for the concurrent Victoria 
River Water Resource Assessment. 

Please cite as they appear. 

Methods report 

CSIRO (2021) Proposed methods report for the Southern Gulf catchments. A report from the 
CSIRO Southern Gulf Water Resource Assessment for the National Water Grid Authority. 
CSIRO, Australia. 

Technical reports 

Devlin K (2023) Pump stations for flood harvesting or irrigation downstream of a storage dam. A 
technical report from the CSIRO Victoria and Southern Gulf Water Resource Assessments for 
the National Water Grid. CSIRO, Australia. 

Devlin K (2024) Conceptual arrangements and costings of hypothetical irrigation developments in 
the Victoria and Southern Gulf catchments. A technical report from the CSIRO Victoria and 
Southern Gulf Water Resource Assessments for the National Water Grid. CSIRO, Australia. 

Gibbs M, Hughes J and Yang A (2024) River model calibration for the Southern Gulf catchments. A 
technical report from the CSIRO Southern Gulf Water Resource Assessment for the National 
Water Grid. CSIRO, Australia. 


Gibbs M, Hughes J, Yang A, Wang B, Marvanek S and Petheram C (2024) River model scenario 
analysis for the Southern Gulf catchments. A technical report from the CSIRO Southern Gulf 
Water Resource Assessment for the National Water Grid. CSIRO, Australia. 

Hayward J (2024) Potential for farm-scale hybrid renewable energy supply options in the Victoria 
and Southern Gulf catchments. A technical report from the CSIRO Victoria and Southern Gulf 
Water Resource Assessments for the National Water Grid. CSIRO, Australia. 

Karim F, Kim S, Ticehurst C, Gibbs M, Hughes J, Marvanek S, Yang A, Wang B and Petheram C 
(2024) Floodplain inundation mapping and modelling for the Southern Gulf catchments. A 
technical report from the CSIRO Southern Gulf Water Resource Assessment for the National 
Water Grid. CSIRO, Australia. 

Lyons P, Barber M, Braedon P and Pert P (2024) Indigenous water values, rights, interests and 
development goals in the Southern Gulf Catchments: A literature review and implications for 
future research. A technical report from the CSIRO Southern Gulf Water Resource 
Assessment for the National Water Grid. CSIRO, Australia 

McJannet D, Yang A and Seo L (2023) Climate data characterisation for hydrological and 
agricultural scenario modelling across the Victoria, Roper and Southern Gulf catchments. A 
technical report from the CSIRO Victoria River and Southern Gulf Water Resource 
Assessments for the National Water Grid. CSIRO, Australia. 

Merrin L, Stratford D, Kenyon R, Pritchard J, Linke S, Ponce Reyes R, Buckworth R, Castellazzi P, 
Costin B, Deng R, Gannon R, Gao S, Gilbey S, Lachish S, McGinness H and Waltham N (2024) 
Ecological assets of the Southern Gulf catchments to inform water resource assessments. A 
technical report from the CSIRO Southern Gulf Water Resource Assessment for the National 
Water Grid. CSIRO, Australia. 

Motson K, Mishra A and Waltham N (2024) A review of water quality studies relevant to northern 
Australia. A technical report from the CSIRO Victoria and Southern Gulf Water Resource 
Assessments for the National Water Grid. CSIRO, Australia. 

Ponce Reyes R, Stratford D, Linke S, Merrin L, Kenyon R, Buckworth R, Deng RA, Hughes J, 
McGinness H, Pritchard J, Seo L and Waltham N (2024) Assessment of the potential 
ecological outcomes of water resource development in the Southern Gulf catchments. A 
technical report from the CSIRO Southern Gulf Water Resource Assessment for the National 
Water Grid. CSIRO, Australia. 

Raiber M, Taylor AR, Dupuy M, Priestley S, Barry K, Crosbie RS, Knapton A and Hodgson G (2024) 
Characterising groundwater resources of the Gilbert River Formation, Camooweal Dolostone 
and Thorntonia Limestone in the Southern Gulf catchments, Queensland and Northern 
Territory. A technical report from the CSIRO Southern Gulf Water Resource Assessment for 
the National Water Grid. CSIRO, Australia. 

Rider Levett Bucknall (2024) Water infrastructure-related costs for the Victoria and Southern Gulf 
catchments. A technical report from the CSIRO Victoria River and Southern Gulf Water 
Resource Assessments for the National Water Grid. CSIRO Australia 


Speed R and Vanderbyl T (2024) Regulatory requirements for land and water development in the 
Northern Territory and Queensland. A technical report from the CSIRO Victoria and Southern 
Gulf Water Resource Assessments for the National Water Grid. CSIRO, Australia. 

Thomas M, Philip S, Zund P, Stockmann U, Hill J, Gregory L, Watson I and Thomas E (2024) Soils 
and land suitability for the Southern Gulf catchments. A technical report from the CSIRO 
Southern Gulf Water Resource Assessment for the National Water Grid. CSIRO, Australia. 

Vanderbyl T (2021) Southern Gulf: Queensland water plans and settings. A technical report from 
the CSIRO Southern Gulf Water Resource Assessment for the National Water Grid. CSIRO, 
Australia. 

Waschka M and Macintosh A (2024) CSIRO Water Resource Assessments: Indigenous rights and 
interests in Queensland and the Northern Territory. A report from Barraband Consulting to 
CSIRO to inform the CSIRO Victoria, Roper and Southern Gulf Water Resource 
Assessments. CSIRO, Australia. 

Webster A, Jarvis D, Jalilov S, Philip S, Oliver Y, Watson I, Rhebergen T, Bruce C, Prestwidge D, 
McFallan S, Curnock M and Stokes C (2024) Financial and socio-economic viability of 
irrigated agricultural development in the Southern Gulf catchments. A technical report from 
the CSIRO Southern Gulf Water Resource Assessment for the National Water Grid. CSIRO, 
Australia. 

Yang A, Petheram C, Marvanek S, Baynes F, Rogers L, Ponce Reyes R, Zund P, Seo L, Hughes J, 
Gibbs M, Wilson PR, Philip S and Barber M (2024) Assessment of surface water storage 
options in the Victoria and Southern Gulf catchments. A technical report from the CSIRO 
Victoria River and Southern Gulf Water Resource Assessments for the National Water Grid. 
CSIRO Australia. 

Catchment report 

Watson I, Bruce C, Philip S, Petheram C and Chilcott C (eds) (2024) Water resource assessment for 
the Southern Gulf catchments. A report from the CSIRO Southern Gulf Water Resource 
Assessment for the National Water Grid. CSIRO, Australia. 

Summary report 

CSIRO (2024) The Southern Gulf Water Resource Assessment. A summary report from the CSIRO 
Southern Gulf Water Resource Assessment for the National Water Grid. CSIRO, Australia. 

Factsheet on key findings 

CSIRO (2024) The Southern Gulf Water Resource Assessment. Key messages of reports to the 
CSIRO Southern Gulf Water Resource Assessment for the National Water Grid. CSIRO, 
Australia. 

 


 

Shortened forms 

SHORT FORM 

FULL FORM 

ABS 

Australian Bureau of Statistics 

ACARA 

Australian Curriculum, Assessment and Reporting Authority 

AE 

adult equivalent 

AEP 

annual exceedance probability 

AHD 

Australian Height Datum 

ALA 

Aboriginal Land Act 1991 (Qld) 

ALRA 

Aboriginal Land Rights (Northern Territory) Act 1976 (Cth) 

AMTD 

adopted middle thread distance 

ANZECC 

Australian and New Zealand Environment and Conservation Council 

APSIM 

Agricultural Production Systems sIMulator 

ARMCANZ 

Agriculture and Resource Management Council of Australia and New Zealand 

ASC 

Australian Soil Classification 

AWC 

available water capacity 

AWRC 

Australian Water Resources Council 

BCR 

benefit-to-cost ratio 

BOM 

Bureau of Meteorology 

CBA 

cost–benefit analysis 

CBR 

cost-to-benefit ratio 

CLA 

Cambrian Limestone Aquifer 

CLCAC 

Carpentaria Land Council Aboriginal Corporation 

CMB 

chloride mass balance 

CMIP 

Coupled Model Intercomparison Project 

CV 

coefficient of variation 

DENR 

Department of Environment and Natural Resources (NT) 

DIDO 

drive-in drive-out 

DIWA 

Directory of Important Wetlands in Australia 

DN 

Nominal Diameter 

DNRME 

Department of Natural Resources, Mines and Energy (Queensland) 

DOGIT 

deeds of grant in trust 

EBITDA 

earnings before interest, taxes, depreciation and amortisation 

EGM96 

Earth Gravitational Model 1996 




SHORT FORM 

FULL FORM 

EIS 

Environmental Impact Statement 

ENSO 

El Niño–Southern Oscillation 

EOS 

end of system 

EPBC Act 

Environment Protection and Biodiversity Conservation Act 1999 (Cth) 

FIFO 

fly-in fly-out 

FSL 

full supply level 

FTE 

full-time equivalent 

GAB 

Great Artesian Basin 

GABORA 

Great Artesian Basin and Other Regional Aquifers 

GCM 

global climate model 

GCM-PS 

global climate model – pattern scaled 

GDE 

groundwater-dependent ecosystem 

GGNTAC 

Gangalidda and Garawa Native Title Aboriginal Corporation 

GM 

gross margin 

GRA 

Gilbert River Aquifer 

GRF 

Gilbert River Formation 

GVAP 

gross value of agricultural production 

GVIAP 

gross value of irrigated agricultural production 

HSD 

health service district 

IEO 

Index of Education and Occupation 

IER 

Index of Economic Resources 

ILUA 

Indigenous Land Use Agreement 

IPA 

Indigenous Protected Area 

IPCC 

Intergovernmental Panel on Climate Change 

IRR 

internal rate of return 

IRSD 

Index of Relative Socio-Economic Disadvantage 

IUCN 

International Union for Conservation of Nature 

JORC 

Joint Ore Reserves Committee 

LGA 

local government area 

MAR 

managed aquifer recharge 

MODIS 

Moderate Resolution Imaging Spectroradiometer 

NAWRA 

Northern Australia Water Resource Assessment 

n.d. 

not dated 

NEM 

National Electricity Market 

NGMA 

Nicholson Groundwater Management Area 

NPF 

Northern Prawn Fishery 

NPV 

net present value 




SHORT FORM 

FULL FORM 

NRM 

Natural Resource Management 

NT 

Northern Territory 

NWPS 

North West Power System 

O&M 

annual operation and maintenance 

PAW 

plant available water 

PAWC 

plant available water capacity 

PBC 

Prescribed Body Corporate 

PE 

potential evaporation 

PET 

potential evapotranspiration 

PHN 

primary health network 

QSNTS 

Queensland South Native Title Services 

RCC 

roller compacted concrete 

RNTBC 

Registered Native Title Body Corporate 

RoNA 

rest of northern Australia 

SA 

South Australia 

SA2 

Statistical Area Level 2 

SEIFA 

Socio-Economic Indexes for Areas 

SGG 

soil generic group 

SILO 

Scientific Information for Land Owners 

SOI 

Southern Oscillation Index 

SSP 

Shared Socio-economic Pathway 

SWAN 

Surface Water Ambient Water Quality Network 

SWL 

standing water level 

TDS 

total dissolved solids 

TraNSIT 

Transport Network Strategic Investment Tool 

UNESCO 

United Nations Educational, Scientific and Cultural Organization 

WA 

Western Australia 



 


Units 

UNIT 

DESCRIPTION 

$ 

dollars 

% 

per cent 

c 

cents 

cm 

centimetre 

d 

day 

dS 

decisiemens 

DS 

dry season 

GL 

gigalitre 

ha 

hectare 

kg 

kilogram 

km 

kilometre 

km2 

square kilometre 

kPa 

kilopascal 

kV 

kilovolt 

kW 

kilowatt 

L 

litre 

m 

metre 

m3 

cubic metre 

mASL 

metres above sea level 

mBGL 

metres below ground level 

mEGM86 

metres (Earth Gravitational Model 1986) 

mEGM96 

metres (Earth Gravitational Model 1996) 

mg 

milligram 

ML 

megalitre 

mm 

millimetre 

MWh 

megawatt hour 

s 

second 

t 

metric tonne 

y 

year 

°C 

degrees Celsius 



 


 

List of figures 

Figure 1-1 Map of Australia showing Assessment area (Southern Gulf catchments) and other 
recent or ongoing CSIRO Assessments ........................................................................................... 3 

Figure 1-2 Number of large dams constructed in Australia and northern Australia over time ..... 8 

Figure 1-3 Schematic of key components and concepts in the establishment of a greenfield 
irrigation development ................................................................................................................. 10 

Figure 1-4 The Southern Gulf catchments .................................................................................... 13 

Figure 2-1 Schematic diagram of key natural components and concepts in the establishment of 
a greenfield irrigation development ............................................................................................. 19 

Figure 2-2 Surface geology of the Southern Gulf catchments ...................................................... 23 

Figure 2-3 Physiographic units of the Southern Gulf catchments ................................................ 25 

Figure 2-4 Major geological provinces of the Southern Gulf catchments .................................... 29 

Figure 2-5 The soil generic groups (SGGs) of the Southern Gulf catchments produced by digital 
soil mapping .................................................................................................................................. 32 

Figure 2-6 Cracking clay (brown Vertosol; SGG 9) Mitchell grass (Astrebla spp.) downs with 
whitewood (Elaeocarpus sp.) and gutta percha (Palaquium spp.) on the Armraynald Plain 
physiographic unit, east of the Leichhardt River .......................................................................... 36 

Figure 2-7 Brown Dermosol (SGG 2) buffel grass (Cenchrus ciliaris) open woodland with silver 
leaf box (Eucalyptus pruinosa) on the Armraynald Plain physiographic unit in the middle reaches 
of the Leichhardt River .................................................................................................................. 36 

Figure 2-8 Red sandy soil (SGG 6.1) open woodland of Darwin box (Eucalyptus tectifica), 
bauhinia (Bauhinia spp.) and Cooktown ironwood (Erythrophleum chlorostachys) near 
Doomadgee on the Armraynald Plain physiographic unit north of the Nicholson River ............. 37 

Figure 2-9 Level to gently undulating cracking clay soils of the Armraynald Plain suitable for 
broadacre irrigation ...................................................................................................................... 38 

Figure 2-10 Soil profile of the brown Vertosol (SGG 9) sampled on the Armraynald Plain 
physiographic unit east of the Leichhardt River ........................................................................... 39 

Figure 2-11 (a) Surface soil pH (top 10 cm) of the Southern Gulf catchments as predicted by 
digital soil mapping and (b) reliability of the prediction .............................................................. 40 

Figure 2-12 (a) Soil thickness of the Southern Gulf catchments as predicted by digital soil 
mapping and (b) reliability of the prediction ................................................................................ 41 

Figure 2-13 (a) Soil surface texture of the Southern Gulf catchments as predicted by digital soil 
mapping and (b) reliability of the prediction ................................................................................ 42 


Figure 2-14 (a) Soil permeability of the Southern Gulf catchments as predicted by digital soil 
mapping and (b) reliability of the prediction ................................................................................ 43 

Figure 2-15 (a) Available water capacity in the upper 100 cm of the soil profile (AWC 100) of the 
Southern Gulf catchments as predicted by digital soil mapping and (b) reliability of the 
prediction ...................................................................................................................................... 44 

Figure 2-16 (a) Surface rockiness in soils of the Southern Gulf catchments represented by 
presence or absence as predicted by digital soil mapping and (b) reliability of the prediction .. 45 

Figure 2-17 Historical rainfall, potential evaporation and rainfall deficit .................................... 47 

Figure 2-18 Historical monthly rainfall (left) and time series of annual rainfall (right) in the 
Southern Gulf catchments at Mount Isa, Doomadgee, Gregory and Burketown ........................ 50 

Figure 2-19 Historical monthly potential evaporation (PE) (left) and time series of annual PE 
(right) in the Southern Gulf catchments at Mount Isa, Doomadgee, Gregory and Burketown ... 51 

Figure 2-20 (a) Coefficient of variation (CV) of annual rainfall and (b) the CV of annual rainfall 
plotted against mean annual rainfall for 99 rainfall stations around Australia ........................... 52 

Figure 2-21 Runs of wet and dry years at Mount Isa, Doomadgee, Gregory and Burketown ..... 54 

Figure 2-22 Percentage change in rainfall and potential evaporation per degree of global 
warming for the 32 Scenario C simulations relative to Scenario A values for the Southern Gulf 
catchments .................................................................................................................................... 56 

Figure 2-23 Spatial distribution of mean annual rainfall across the Southern Gulf catchments 
under scenarios (a) Cwet, (b) Cmid and (c) Cdry .......................................................................... 56 

Figure 2-24 (a) Monthly rainfall and (b) potential evaporation for the Southern Gulf catchments 
under scenarios A and C ................................................................................................................. 57 

Figure 2-25 Simplified schematic diagram of terrestrial water balance in the Southern Gulf 
catchments .................................................................................................................................... 60 

Figure 2-26 Simplified regional hydrogeology of the Southern Gulf catchments ........................ 62 

Figure 2-27 Two-dimensional conceptual schematic of the interconnected aquifer system and 
its variability .................................................................................................................................. 64 

Figure 2-28 Gregory River at Riversleigh Road ............................................................................. 65 

Figure 2-29 Lawn Hill Gorge .......................................................................................................... 66 

Figure 2-30 The Gregory River receives groundwater discharge from the Cambrian Limestone 
Aquifer ........................................................................................................................................... 67 

Figure 2-31 Full extent of the Georgina Basin and Carpentaria Sub-basin of the Great Artesian 
Basin. Inset map shows full extent of Great Artesian Basin ......................................................... 68 

Figure 2-32 Groundwater bore yields for major aquifers across the Southern Gulf catchments 69 

Figure 2-33 Groundwater salinity for major aquifers in the Southern Gulf catchments ............. 70 

Figure 2-34 Annual recharge estimates for the Southern Gulf catchments ................................. 72 


Figure 2-35 Summary of recharge statistics to outcropping areas of key hydrogeological units 
across the Southern Gulf catchments ........................................................................................... 73 

Figure 2-36 Spatial distribution of groundwater discharge classes including surface water – 
groundwater connectivity across the Southern Gulf catchments ................................................ 75 

Figure 2-37 Modelled streamflow under natural conditions ....................................................... 76 

Figure 2-38 Streamflow observation data availability in the Southern Gulf catchments ............ 78 

Figure 2-39 Median annual streamflow (50% exceedance) in the Southern Gulf catchments 
under Scenario A ........................................................................................................................... 79 

Figure 2-40 (a) 20% and (b) 80% exceedance of annual streamflow in the Southern Gulf 
catchments under Scenario A ....................................................................................................... 80 

Figure 2-41 Catchment area and elevation profile from the upper tributaries in each catchment 
to the mouth along the (a) Gregory–Nicholson River and (b) Leichhardt River ........................... 80 

Figure 2-42 Mean annual (a) rainfall and (b) runoff across the Southern Gulf catchments under 
Scenario A ..................................................................................................................................... 81 

Figure 2-43 Annual runoff at (a) 20%, (b) 50% and (c) 80% exceedance across the Southern Gulf 
catchments under Scenario A ....................................................................................................... 82 

Figure 2-44 Total runoff across the Southern Gulf catchments under Scenario A showing (a) 
time series of annual runoff and (b) monthly runoff averaged across the catchments .............. 82 

Figure 2-45 Flood inundation map of the Southern Gulf catchments .......................................... 84 

Figure 2-46 Flood inundation in the Southern Gulf catchments for a flood event of 1 in 38 
annual exceedance probability (AEP) in March 2023 ................................................................... 85 

Figure 2-47 Peak flood discharge and annual exceedance probability (AEP) at (a) gauge 912107A 
(Nicholson River at Connolly’s Hole), (b) gauge 912105A (Gregory River at Riversleigh) and (c) 
gauge 913007B (Leichhardt River at Floraville) ............................................................................ 86 

Figure 2-48 Minimum observed September streamflow at two stream gauge locations on the 
Gregory River ................................................................................................................................ 87 

Figure 2-49 Minimum monthly flow over 132 years of simulation for the month of October .... 88 

Figure 2-50 Instream waterhole evolution in a reach of the Flinders River ................................. 89 

Figure 2-51 The Leichhardt River near Kajabbi looking south towards the Isa highlands. In the 
highly seasonal climate of the Southern Gulf catchments, springs and persistent waterholes 
provide important ecological refugia during the dry season ....................................................... 89 

Figure 2-52 Location of river reaches containing permanent water in the Southern Gulf 
catchments .................................................................................................................................... 90 

Figure 2-53 Accelerated erosion contributes sediment to streamflow........................................ 92 

Figure 2-54 Water quality samples for selected constituents on the Gregory River at Riversleigh 
(A912005A), Gunpowder Creek at Gunpowder (913006A) and Leichhardt River at Floraville 
Homestead (913007B) .................................................................................................................. 93 


Figure 3-1 Schematic diagram of key components of the living and built environment to be 
considered in establishing a greenfield irrigation development ................................................ 101 

Figure 3-2 Conceptual diagram of selected ecological assets of the Southern Gulf catchments 
..................................................................................................................................................... 106 

Figure 3-3 Estuarine crocodiles inhabit fresh and saltwater environments ............................... 108 

Figure 3-4 Location of protected areas and important wetlands within the Southern Gulf 
catchments Assessment area...................................................................................................... 109 

Figure 3-5 Regional ecosystem biodiversity status in the Queensland part of the Southern Gulf 
catchments .................................................................................................................................. 110 

Figure 3-6 Brolgas flying into the sunset at Lake Moondarra ..................................................... 117 

Figure 3-7 Land subject to inundation (potential floodplain wetlands) and important wetlands in 
the Southern Gulf catchments .................................................................................................... 119 

Figure 3-8 This saltpan area in northern Australia is typical in being located between mangrove 
and saltmarsh areas .................................................................................................................... 122 

Figure 3-9 Australian bustards are common in grasslands and woodlands across northern 
Australia ...................................................................................................................................... 123 

Figure 3-10 Location of saltpans in the Southern Gulf catchments marine region .................... 124 

Figure 3-11 The O’Shannassy River – one of the northern Australian rivers where catfish are 
found ........................................................................................................................................... 126 

Figure 3-12 Modelled potential species distribution for fork-tailed catfish (Neoarius graeffei) in 
the Southern Gulf catchments .................................................................................................... 127 

Figure 3-13 Magpie goose perched on a fallen tree branch ....................................................... 129 

Figure 3-14 Distribution of species listed under the Environment Protection and Biodiversity 
Conservation Act 1999 and by the NT and Queensland governments in the Southern Gulf 
catchments .................................................................................................................................. 130 

Figure 3-15 Boundaries of the Australian Bureau of Statistics Statistical Area Level 2 (SA2) 
regions used for demographic data in this analysis.................................................................... 135 

Figure 3-16 Land use classification for the Southern Gulf catchments ...................................... 139 

Figure 3-17 Regions in the Northern Prawn Fishery and the North West Minerals Province ... 143 

Figure 3-18 Main commodity mineral occurrences and exploration tenements in the Southern 
Gulf catchments .......................................................................................................................... 144 

Figure 3-19 Local government areas and the Tropical North Queensland tourism region that 
statistics on tourism visitation are extracted from ..................................................................... 150 

Figure 3-20 Road rankings and conditions in the vicinity of the Southern Gulf catchments ..... 153 

Figure 3-21 Roads accessible to Type 2 vehicles in the vicinity of the Southern Gulf catchments: 
minor roads are not classified ..................................................................................................... 154 


Figure 3-22 Common configurations of heavy freight vehicles used for transporting agricultural 
goods in Australia ........................................................................................................................ 155 

Figure 3-23 Road conditions and distance to market impact the economics of development in 
the Southern Gulf catchments. ................................................................................................... 155 

Figure 3-24 Mean speed achieved for freight vehicles on roads in the vicinity of the Southern 
Gulf catchments .......................................................................................................................... 156 

Figure 3-25 Many roads are gravel in the Southern Gulf catchments, and often impassable in 
the wet season ............................................................................................................................ 158 

Figure 3-26 Annual amounts of trucking in the Southern Gulf catchments and the locations of 
pastoral properties and ports ..................................................................................................... 159 

Figure 3-27 Electricity generation and transmission network and pipelines in the Southern Gulf 
catchments .................................................................................................................................. 160 

Figure 3-28 Solar photovoltaic capacity factors in the Southern Gulf catchments .................... 162 

Figure 3-29 Wind capacity factors in the Southern Gulf catchments ......................................... 163 

Figure 3-30 Location, type and volume of annual licensed surface water and groundwater 
entitlements across the Southern Gulf catchments ................................................................... 165 

Figure 3-31 Exclusive Aboriginal lands and pastoral interests make up the majority of the 
Southern Gulf catchments .......................................................................................................... 174 

Figure 3-32 The extent of native title claims and determinations over the Southern Gulf 
catchments .................................................................................................................................. 175 

Figure 3-33 Indigenous protected areas and other protected areas in the Southern Gulf 
catchments as of April 2020........................................................................................................ 176 

Figure 3-34 Indigenous Land Use Agreements (ILUAs) ............................................................... 177 

Figure 4-1 Schematic of agriculture and aquaculture enterprises as well as crop and/or forage 
integration with existing beef enterprises to be considered in the establishment of a greenfield 
irrigation development ............................................................................................................... 206 

Figure 4-2 Area (ha) of the Southern Gulf catchments mapped in each of the land suitability 
classes for 14 selected land use combinations (crop group × season × irrigation type) ............ 214 

Figure 4-3 Agricultural versatility index map for the Southern Gulf catchments....................... 215 

Figure 4-4 Climate comparisons of Southern Gulf catchments’ sites with established irrigation 
areas at Kununurra (WA) and Mareeba (Queensland) ............................................................... 219 

Figure 4-5 Annual cropping calendar for irrigated agricultural options in the Southern Gulf 
catchments .................................................................................................................................. 221 

Figure 4-6 Soil wetness indices that indicate when seasonal trafficability constraints are likely to 
occur on sands, Kandosols (loamy sands) and Vertosols (high clay) with a Gregory climate for 
two thresholds (a) 80% and (b) 70% of the maximum plant available water capacity .............. 222 

Figure 4-7 Influence of planting date on rainfed grain sorghum yield at Gregory for a (a) 
Kandosol and (b) Vertosol ........................................................................................................... 224 


Figure 4-8 Influence of available irrigation water on grain sorghum yields for planting dates of 
(a) 1 February and (b) 1 August, for a Vertosol with a Gregory climate .................................... 225 

Figure 4-9 Fluctuations in seedless watermelon prices at Melbourne wholesale markets from 
April 2020 to February 2023 ....................................................................................................... 234 

Figure 4-10 Modelled land suitability for Crop Group 7 (e.g. sorghum (grain) or maize) using 
furrow irrigation in the (a) wet season and (b) dry season ........................................................ 246 

Figure 4-11 Sorghum (grain) ....................................................................................................... 248 

Figure 4-12 Modelled land suitability for mungbean (Crop Group 10) in the dry season using (a) 
furrow irrigation and (b) spray irrigation .................................................................................... 250 

Figure 4-13 Mungbean ................................................................................................................ 250 

Figure 4-14 Modelled land suitability for soybean (Crop Group 10) in the dry season using (a) 
furrow irrigation and (b) spray irrigation .................................................................................... 253 

Figure 4-15 Soybean.................................................................................................................... 253 

Figure 4-16 Modelled land suitability for peanut (Crop Group 6) using spray irrigation in the (a) 
wet season and (b) dry season ................................................................................................... 256 

Figure 4-17 Peanut ...................................................................................................................... 256 

Figure 4-18 Modelled land suitability for cotton (Crop Group 7) using furrow irrigation in the (a) 
wet season and (b) dry season ................................................................................................... 260 

Figure 4-19 Cotton ...................................................................................................................... 260 

Figure 4-20 Modelled land suitability for Rhodes grass (Crop Group 14) using (a) spray irrigation 
and (b) furrow irrigation ............................................................................................................. 263 

Figure 4-21 Rhodes grass ............................................................................................................ 264 

Figure 4-22 Modelled land suitability for Cavalcade (Crop Group 13) in the wet season using (a) 
spray irrigation and (b) furrow irrigation .................................................................................... 266 

Figure 4-23 Lablab ....................................................................................................................... 268 

Figure 4-24 Modelled land suitability for (a) cucurbits (e.g. rockmelon, Crop Group 3) using 
trickle irrigation in the dry season and (b) root crops such as onion (Crop Group 6) using spray 
irrigation in the wet season ........................................................................................................ 270 

Figure 4-25 Rockmelon ............................................................................................................... 270 

Figure 4-26 Modelled land suitability for (a) mango (Crop Group 1) and (b) lime (Crop Group 2), 
both grown using trickle irrigation.............................................................................................. 273 

Figure 4-27 Mango ...................................................................................................................... 273 

Figure 4-28 Modelled land suitability for Indian sandalwood (Crop Group 15) grown using (a) 
trickle or (b) furrow irrigation ..................................................................................................... 276 

Figure 4-29 Indian sandalwood and host plants ......................................................................... 276 

Figure 4-30 Black tiger prawns .................................................................................................... 280 


Figure 4-31 Barramundi .............................................................................................................. 280 

Figure 4-32 Schematic of marine aquaculture farm ................................................................... 282 

Figure 4-33 Land suitability in the Southern Gulf catchments for marine species aquaculture in 
(a) lined ponds and (b) earthen ponds ....................................................................................... 286 

Figure 4-34 Land suitability in the Southern Gulf catchments for freshwater species aquaculture 
in (a) lined ponds and (b) earthen ponds ................................................................................... 287 

Figure 5-1 Schematic of key engineering and agricultural components to be considered in the 
establishment of a water resource and greenfield irrigation development .............................. 296 

Figure 5-2 Hydrogeological units with potential for future groundwater resource development 
..................................................................................................................................................... 306 

Figure 5-3 Groundwater dependent ecosystems along Lawn Hill Creek ................................... 308 

Figure 5-4 Thickness of the Georgina Basin in the Southern Gulf catchments .......................... 309 

Figure 5-5 Hydrogeological cross-section through the Cambrian Limestone Aquifer in the 
Georgina Basin and south-west of the Southern Gulf catchments ............................................ 310 

Figure 5-6 Depth to standing water level (SWL) of the Cambrian Limestone Aquifer (CLA)...... 311 

Figure 5-7 Location of the Undilla Sub-basin groundwater flow model in relation to the 
Southern Gulf catchments and portions of the model that coincide with the Lawn Hill Creek and 
Gregory subcatchments and Nicholson Groundwater Management Area ................................ 312 

Figure 5-8 Depth to the top of the Gilbert River Aquifer (GRA) ................................................. 314 

Figure 5-9 South-west to north-east cross-section traversing the Great Artesian Basin in the 
Southern Gulf catchments. ......................................................................................................... 315 

Figure 5-10 Depth to standing water level of the Gilbert River Aquifer (GRA) .......................... 316 

Figure 5-11 Uncontrolled artesian flow from the Gilbert River Aquifer at the Burketown 
groundwater bore ....................................................................................................................... 318 

Figure 5-12 Types of managed aquifer recharge ........................................................................ 319 

Figure 5-13 Managed aquifer recharge (MAR) opportunities for the Southern Gulf catchments 
independent of distance from a water source for recharge ...................................................... 321 

Figure 5-14 (a) Managed aquifer recharge (MAR) opportunities in the Southern Gulf catchments 
within 5 km of major rivers and (b) aquifer underlying the MAR opportunity classes .............. 322 

Figure 5-15 Potential storage sites in the Southern Gulf catchments based on minimum cost per 
megalitre storage capacity .......................................................................................................... 326 

Figure 5-16 Potential storage sites in the Southern Gulf catchments based on minimum cost per 
megalitre yield at the dam wall .................................................................................................. 328 

Figure 5-17 Julius Dam on the Leichhardt River ......................................................................... 329 

Figure 5-18 Southern Gulf catchments hydro-electric power generation opportunity map ..... 330 

Figure 5-19 Cumulative yield at 85% annual time reliability versus cumulative cost of water in 
$/ML and change in the end-of-system (EOS) volume in the Southern Gulf catchments ......... 335 


Figure 5-20 Location of listed species, water-dependent assets and aggregated modelled 
habitat in the vicinity of the potential dam site on Gunpowder Creek dam AMTD 66 km and 
reservoir extent ........................................................................................................................... 337 

Figure 5-21 Potential dam site on Gunpowder Creek AMTD 66 km: cost and yield at the dam 
wall .............................................................................................................................................. 338 

Figure 5-22 Location of listed species, water-dependent assets and aggregated modelled 
habitat in the vicinity of the potential dam site on the Gregory River AMTD 174 km ............... 340 

Figure 5-23 Potential dam site on Gregory River AMTD 174 km: cost and yield at the dam wall 
..................................................................................................................................................... 341 

Figure 5-24 Schematic cross-section of sheet piling weir ........................................................... 343 

Figure 5-25 Rectangular ringtank and 500 ha of cotton in the Flinders catchment (Queensland) 
..................................................................................................................................................... 345 

Figure 5-26 Suitability of land for large farm-scale ringtanks in the Southern Gulf catchments 346 

Figure 5-27 Annual reliability of diverting annual system and reach target volumes for varying 
pump start thresholds ................................................................................................................. 348 

Figure 5-28 Annual reliability of diverting annual system and reach target volumes for varying 
pump start thresholds with annual diversion commencement flow requirement of 150 GL ... 350 

Figure 5-29 Annual reliability of diverting annual system and reach target volumes for varying 
pump start thresholds assuming pumping capacity of 10 days ................................................. 351 

Figure 5-30 Annual reliability of diverting annual system and reach target volumes for varying 
pump rates assuming a pump start threshold of 600 ML/day ................................................... 352 

Figure 5-31 50% annual exceedance (median) streamflow relative to Scenario A in the Southern 
Gulf catchments for a pump start threshold of 600 ML/day and a pump capacity of 20 days .. 353 

Figure 5-32 80% annual exceedance streamflow relative to Scenario A in the Southern Gulf 
catchments for a pump start threshold of 600 ML/day and a pump capacity of 20 days ......... 354 

Figure 5-33 Most economically suitable locations for large farm-scale gully dams in the 
Southern Gulf catchments .......................................................................................................... 360 

Figure 5-34 Suitability of soils for construction of gully dams in the Southern Gulf catchments 
..................................................................................................................................................... 361 

Figure 5-35 Reported conveyance losses from irrigation systems across Australia .................. 369 

Figure 5-36 Efficiency of different types of irrigation system .................................................... 370 

Figure 6-1 Schematic diagram of key components affecting the commercial viability of a 
potential greenfield irrigation development .............................................................................. 379 

Figure 6-2 Locations of the five dams used in this review .......................................................... 400 

Figure 6-3 Trends in gross value of agricultural production (GVAP) in (a) Australia and (b) 
Queensland over 40 years (1981–2021) ..................................................................................... 403 


Figure 6-4 National trends for increasing gross value of irrigated agricultural production (GVIAP) 
as available water supplies have increased for (a) fruits, (b) vegetables, (c) fruits and vegetables 
combined, and (d) total agriculture ............................................................................................ 404 

Figure 6-5 Queensland’s north-west region used in the input–output (I–O) analyses relative to 
the Southern Gulf catchments Assessment area ........................................................................ 410 

Figure 7-1 Schematic diagram of the components where key risks can manifest when 
considering the establishment of a greenfield irrigation or aquaculture development ............ 417 

Figure 7-2 Locations of the river system modelling nodes at which flow–ecology dependencies 
were assessed (numbered) and the locations of hypothetical water resource developments in 
the Southern Gulf catchments .................................................................................................... 429 

Figure 7-3 Riparian vegetation along the Leichhardt River – riparian zones are often more fertile 
and productive than surrounding terrestrial vegetation ............................................................ 436 

Figure 7-4 Spatial heatmap of habitat-weighted changes in flow for sawfish, considering the 
assets important locations across the catchment ...................................................................... 437 

Figure 7-5 Habitat-weighted change in sawfish flow dependencies by scenario across model 
nodes ........................................................................................................................................... 438 

Figure 7-6 Habitat-weighted change in swimming, diving and grazing waterbirds flow 
dependencies by scenario across model nodes ......................................................................... 441 

Figure 7-7 Habitat-weighted change in floodplain wetlands flow dependencies by scenario 
across model nodes .................................................................................................................... 444 

Figure 7-8 Lake Moondarra near Mount Isa is used for urban water supply and is a popular 
water and recreational reserve................................................................................................... 449 

Figure 7-9 Mean change associated with each asset’s important metrics across water harvesting 
increments of system target and pump-start threshold with no annual diversion 
commencement flow requirement and pump rate of 30 days .................................................. 450 

Figure 7-10 The invasion curve with biosecurity actions taken at various stages ..................... 461 

Figure 7-11 Farm biosecurity signage available through www.farmbiosecurity.com.au ........... 462 

Figure 7-12 An extratidal flat on the Karumba Plain near Burketown, with white salt crystals 
either side of a shallow natural drainage line. Salt-tolerant samphire and mangrove species can 
be seen in the background. ......................................................................................................... 475 

Figure 7-13 Example of salt-affected areas on the northern part of the Armraynald Plain ...... 476 

 


List of tables 

Table 2-1 Soil generic groups (SGGs), descriptions, management considerations and correlations 
to Australian Soil Classification (ASC) for the Southern Gulf catchments .................................... 33 

Table 2-2 Area and proportions covered by each soil generic group (SGG) in the Southern Gulf 
catchments .................................................................................................................................... 35 

Table 2-3 Projected sea-level rise for the coast of the Southern Gulf catchments ...................... 57 

Table 2-4 Streamflow metrics at selected gauging stations in the Southern Gulf catchments ... 77 

Table 2-5 Summary of water quality data for the open Southern Gulf catchments sites, with 
values of minimum, median and maximum for each site and each water quality parameter .... 91 

Table 3-1 Categories of biodiversity status of the Queensland regional ecosystems ................ 112 

Table 3-2 Freshwater, marine and terrestrial ecological assets with freshwater flow 
dependences in the Southern Gulf catchments ......................................................................... 116 

Table 3-3 Nationally important wetlands in the Southern Gulf catchments ............................. 118 

Table 3-4 Definition of threatened categories under the Commonwealth Environment 
Protection and Biodiversity Conservation Act 1999, the NT wildlife classification system, and the 
Queensland Nature Conservation Act 1992 ................................................................................ 131 

Table 3-5 Major demographic indicators for the Southern Gulf catchments ............................ 134 

Table 3-6 Socio-Economic Indexes for Areas (SEIFA) scores of relative socio-economic advantage 
for the Southern Gulf catchments .............................................................................................. 136 

Table 3-7 Key employment data for the Southern Gulf catchments .......................................... 137 

Table 3-8 Value of agricultural production estimated for the Southern Gulf catchments and the 
value of agricultural production for Queensland for 2020–21 ................................................... 140 

Table 3-9 Indicative numbers for employment in different types of mining operations in the 
Southern Gulf catchments .......................................................................................................... 145 

Table 3-10 Resource and reserve data for several major deposits in and on the margins of the 
Southern Gulf catchments .......................................................................................................... 146 

Table 3-11 Global water consumption in the mining and refining of selected metals .............. 148 

Table 3-12 Overview of commodities (excluding livestock) annually transported into and out of 
the Southern Gulf catchments .................................................................................................... 157 

Table 3-13 Unallocated surface water in the Queensland part of the Southern Gulf catchments 
..................................................................................................................................................... 166 

Table 3-14 Schools servicing the Southern Gulf catchments ..................................................... 168 

Table 3-15 Number and percentage of unoccupied dwellings and population for the Southern 
Gulf catchments .......................................................................................................................... 169 

Table 4-1 Land suitability classes based on FAO (1976, 1985) as used in the Assessment ........ 212 


Table 4-2 Crop groups and individual land uses evaluated for irrigation (and rainfed) potential 
..................................................................................................................................................... 213 

Table 4-3 Qualitative land evaluation observations in Southern Gulf catchments areas A to F 
shown in Figure 4-3 ..................................................................................................................... 216 

Table 4-4 Crop options for which performance was evaluated in terms of water use, yields and 
gross margins .............................................................................................................................. 218 

Table 4-5 Soil water content at sowing, and rainfall for the 90-day period following sowing for 
three sowing dates, based on a Gregory climate on a Vertosol ................................................. 223 

Table 4-6 Performance metrics for broadacre cropping options in the Southern Gulf 
catchments: applied irrigation water, crop yield and gross margin (GM) for four environments 
..................................................................................................................................................... 227 

Table 4-7 Breakdown of variable costs relative to revenue for broadacre crop options ........... 231 

Table 4-8 Sensitivity of cotton crop gross margins ($/ha) to variation in yield, lint prices and 
distance to gin ............................................................................................................................. 232 

Table 4-9 Sensitivity of forage (Rhodes grass) crop gross margins ($/ha) to variation in yield and 
hay price ...................................................................................................................................... 232 

Table 4-10 Performance metrics for horticulture options in the Southern Gulf catchments: 
annual applied irrigation water, crop yield and gross margin .................................................... 233 

Table 4-11 Sensitivity of watermelon crop gross margins ($/ha) to variation in melon prices and 
freight costs ................................................................................................................................. 235 

Table 4-12 Performance metrics for plantation tree crop options in the Southern Gulf 
catchments: annual applied irrigation water, crop yield and gross margin ............................... 236 

Table 4-13 Likely annual irrigated crop planting windows, suitability and viability in the 
Southern Gulf catchments .......................................................................................................... 239 

Table 4-14 Sequential cropping options for Kandosols .............................................................. 240 

Table 4-15 Production and financial outcomes from the different irrigated forage and beef 
production options for a representative property in the Southern Gulf catchments ................ 243 

Table 4-16 Summary information relevant to the cultivation of cereals, using sorghum (grain) as 
an example .................................................................................................................................. 247 

Table 4-17 Summary information relevant to the cultivation of pulses, using mungbean as an 
example ....................................................................................................................................... 251 

Table 4-18 Summary information relevant to the cultivation of oilseed crops, using soybean as 
an example .................................................................................................................................. 254 

Table 4-19 Summary information relevant to the cultivation of root crops, using peanut as an 
example ....................................................................................................................................... 257 

Table 4-20 Summary information relevant to the cultivation of cotton .................................... 261 

Table 4-21 Rhodes grass production for hay over 1 year of a 6-year cycle ................................ 264 


Table 4-22 Cavalcade production over a 1-year cycle ................................................................ 267 

Table 4-23 Summary information relevant to row crop horticulture production, with rockmelon 
as an example ............................................................................................................................. 271 

Table 4-24 Summary information relevant to tree crop horticulture production, with mango as 
an example .................................................................................................................................. 274 

Table 4-25 Summary information for Indian sandalwood production ....................................... 277 

Table 4-26 Indicative capital and operating costs for a range of generic aquaculture 
development options .................................................................................................................. 288 

Table 4-27 Gross revenue targets required to achieve target internal rates of return (IRR) for 
aquaculture developments with different combinations of capital costs and operating costs . 290 

Table 5-1 Summary of capital costs, yields and costs per ML supply, including operation and 
maintenance ............................................................................................................................... 300 

Table 5-2 Opportunity-level estimates of the potential scale of groundwater resource 
development opportunities in the Southern Gulf catchments .................................................. 304 

Table 5-3 Summary of estimated costs for a 250 ha irrigation development using groundwater 
..................................................................................................................................................... 307 

Table 5-4 Mean annual groundwater balance for the Cambrian Limestone Aquifer (CLA) in the 
Undilla Sub-basin of the Georgina Basin for a 109-year climate sequence (1910–2019) and areas 
of the CLA that coincide with the Lawn Hill Creek and Gregory subcatchments and Nicholson 
Groundwater Management Area (NGMA) ................................................................................. 313 

Table 5-5 Potential dam sites in the Southern Gulf catchments examined as part of the 
Assessment ................................................................................................................................. 331 

Table 5-6 Summary comments for potential dams in the Southern Gulf catchments ............... 332 

Table 5-7 Estimated construction cost of 3 m high sheet piling weir......................................... 343 

Table 5-8 Effective volume after net evaporation and seepage for ringtanks of three mean 
water depths, under three seepage rates, near Century Mine in the Southern Gulf catchments 
..................................................................................................................................................... 355 

Table 5-9 Indicative costs for a 4000 ML ringtank ...................................................................... 357 

Table 5-10 Annualised cost for the construction and operation of three ringtank configurations 
..................................................................................................................................................... 357 

Table 5-11 Equivalent annual cost per megalitre for two different capacity ringtanks under 
three seepage rates based on a climate station near the Century Zinc Mine in the Southern Gulf 
catchments .................................................................................................................................. 358 

Table 5-12 Actual costs of four gully dams in northern Queensland ......................................... 362 

Table 5-13 Cost of three hypothetical large farm-scale gully dams of capacity 4 GL ................. 363 

Table 5-14 High-level breakdown of capital costs for three hypothetical large farm-scale gully 
dams of capacity 4 GL ................................................................................................................. 363 


Table 5-15 Effective volumes and cost per megalitre for a 4 GL storage with different mean 
depths and seepage loss rates based on a climate station at the Century Zinc Mine in the 
Southern Gulf catchments .......................................................................................................... 364 

Table 5-16 Cost of construction and operation of three hypothetical 4 GL gully dams............. 364 

Table 5-17 Equivalent annualised cost and effective volume for three hypothetical 4 GL gully 
dams with various mean depths and seepage loss rates based on climate data at Victoria River 
Downs Station in the Victoria catchment ................................................................................... 365 

Table 5-18 Summary of conveyance and application efficiencies .............................................. 367 

Table 5-19 Water distribution and operational efficiency as nominated in water resource plans 
for four irrigation water supply schemes in Queensland ........................................................... 368 

Table 5-20 Application efficiencies for surface, spray and micro irrigation systems ................. 371 

Table 6-1 Types of questions that users can answer using the tools in this chapter ................. 382 

Table 6-2 Indicative capital costs for developing three irrigation schemes based on the most 
cost-effective dam sites identified in the Southern Gulf catchments ........................................ 386 

Table 6-3 Assumed indicative capital and operating costs for new off- and on-farm irrigation 
infrastructure .............................................................................................................................. 387 

Table 6-4 Price irrigators can afford to pay for water, based on the type of farm, the farm water 
use and the farm annual gross margin (GM), while meeting a target 10% internal rate of return 
(IRR) ............................................................................................................................................. 389 

Table 6-5 Farm gross margins (GMs) required in order to cover the costs of off-farm water 
infrastructure (at the supplier’s target internal rate of return (IRR)) ......................................... 391 

Table 6-6 Water pricing required in order to cover costs of off-farm irrigation scheme 
development (dam, water distribution, and supporting infrastructure) at the investors target 
internal rate of return (IRR) ........................................................................................................ 392 

Table 6-7 Farm gross margins (GMs) required in order to achieve target internal rates of return 
(IRR), given various capital costs of farm development (including an on-farm water source) .. 393 

Table 6-8 Equivalent costs of water per ML for on-farm water sources with various capital costs 
of development, at the internal rate of return (IRR) targeted by the investor .......................... 394 

Table 6-9 Risk adjustment factors for target farm gross margins (GMs), accounting for the 
effects of the reliability and severity (level of farm performance in ‘failed’ years) of the periodic 
risk of water reliability ................................................................................................................ 396 

Table 6-10 Risk adjustment factors for target farm gross margins (GMs) accounting for the 
effects of reliability and the timing of periodic risks .................................................................. 397 

Table 6-11 Risk adjustment factors for target farm gross margins (GMs), accounting for the 
effects of learning risks ............................................................................................................... 398 

Table 6-12 Summary characteristics of the five dams used in this review................................. 401 

Table 6-13 Summary of key issues and potential improvements arising from a review of recent 
dam developments ..................................................................................................................... 402 


Table 6-14 Indicative costs of agricultural processing facilities .................................................. 405 

Table 6-15 Indicative costs of road and electricity infrastructure .............................................. 406 

Table 6-16 Indicative road transport costs between the Southern Gulf catchments and key 
markets and ports ....................................................................................................................... 406 

Table 6-17 Indicative costs of community facilities .................................................................... 407 

Table 6-18 Key 2021 data comparing the Southern Gulf catchments with the related I–O 
analysis region ............................................................................................................................. 410 

Table 6-19 Regional economic impact estimated by I–O analysis for the total construction phase 
of an irrigated agricultural development based on estimated Type ll multipliers determined 
from the north-west Queensland I–O models ............................................................................ 411 

Table 6-20 Estimated regional economic impact per year in the Southern Gulf catchments 
resulting from four scales of direct increase in agricultural output (rows) for the different 
categories of agricultural activity (columns) using the I–O model for north-west Queensland 413 

Table 6-21 Estimated impact on annual household incomes and full-time equivalent (FTE) jobs 
within the Southern Gulf catchments resulting from four scales of direct increase in agricultural 
output (rows) for the various categories of agricultural activity (columns) ............................... 414 

Table 7-1 Water resource development and climate scenarios explored in this ecology analysis 
..................................................................................................................................................... 430 

Table 7-2 Ecological assets used in the Southern Gulf catchments Water Resource Assessment 
and the different ecology groups used in this analysis............................................................... 432 

Table 7-3 Reporting qualitative values for the flow dependencies modelling as rank percentile 
change of the hydrometrics ........................................................................................................ 434 

Table 7-4 Scenarios of different hypothetical instream dam locations showing mean changes of 
ecology flows for groups of assets across each asset’s respective catchment assessment nodes 
..................................................................................................................................................... 447 

Table 7-5 Examples of significant pest and disease threats to plant industries in the Southern 
Gulf catchments .......................................................................................................................... 455 

Table 7-6 Regional weed priorities and their management actions in Southern Gulf catchments 
..................................................................................................................................................... 457 

Table 7-7 High-risk freshwater pest fish threats to the Southern Gulf catchments .................. 459 

Table 7-8 Water quality variables reviewed – their impacts on the environment, aquatic ecology 
and human health ....................................................................................................................... 468