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Lower Darling

The lower Darling River flows from the Menindee Lakes to its junction with the River Murray at Wentworth. The catchment is located on the semi-arid plains of south-western New South Wales, where most of the landscape has an elevation of less than 100 m and rainfall of less than 300 mm.

There is a very small amount of run-off within this catchment and nearly all the water flowing through the lower Darling comes from the rivers of southern Queensland and northern New South Wales through the Barwon–Darling river system.

The Menindee Lakes at the head of the lower Darling catchment is a natural system of 7 large lakes that were modified for water storage in the 1960s. The water is used to supply urban water to Broken Hill; supplement urban and irrigation water supplies to New South Wales, Victoria and South Australia; and provide irrigation water to landholders near the lakes.

The Menindee Lakes provide important habitat for waterbirds and aquatic life, as do the lakes associated with the ancestral branch of the river, the Great Darling Anabranch. 

The region is sparsely populated with a few small towns, such as Menindee, Pooncarie and Wentworth, which provide a basic level of services to the community and the surrounding rural population. Most of the catchment is used for grazing, mainly sheep, or is native vegetation. There are pockets of cropping and horticulture, especially grapes, where irrigation water is available. Tourism is important to the region, especially fishing.

Snapshot

Catchment area

3% of the Murray–Darling Basin

River length

530 km

Tributaries

(lower) Darling River

Distributaries

Great Darling Anabranch

Towns include

Menindee,  Wentworth

Water storages

Lakes Menindee, Cawndilla, Pamamaroo and Wetherell (1,730 GL)

Water users

Urban water supply, stock, domestic and irrigation

The landscape and its water

The Darling River travels as a deep channel in the flat, dry floodplains of western New South Wales. Below the Menindee Lakes, the river has 2 large and distinct channels — its main channel, the lower Darling River, and its ancestral channel, the Great Darling Anabranch. The Great Darling Anabranch has a number of overflow lakes that can hold water for prolonged periods following a flood. It branches from the main channel of the river about 55 km south of Menindee and joins the River Murray downstream of Wentworth. Flows can also reach the Great Darling Anabranch from the lakes system through Tandou Creek and several other minor creeks.

The general topography of the catchment is flat, with elevation less than 100 m across most of the floodplain area. The low gradient of the land to the north of Menindee means that flood peaks may take a long time to reach the lower Darling. At its confluence with the River Murray, the elevation of the Darling is less than 50 m.

The climate of the lower Darling catchment is semi-arid and with one of the lowest rainfall regions of New South Wales. Average annual rainfall ranges between 220 and 280 mm across the catchment. The low rainfall and high summer temperatures result in very high evaporation rates across the catchment – the wide and shallow Menindee Lakes are particularly affected.

River flows in the lower Darling result from seasonal rainfall and storms in the catchment and upper catchments. Floods generally occur as a result of high rainfall in the northern and eastern catchments of the northern Basin.

Groundwater in the catchment is contained in the Darling Alluvium (associated with the Darling River) and fractured rock aquifers beneath the Murray and Darling geological basins.

People, industry and water use

The lower Darling River and the River Murray flow through the traditional land of many Aboriginal nations, and the rivers and their floodplains have long been important for sustenance and spirituality. The land around the confluence of the Darling and Murray rivers includes the land of the Barkindji, Maraura, Muthi Muthi and Nyeri Nyeri Aboriginal nations. Along the Murray River and into the lower lands of the Darling catchment (from about Mildura to South Australia) is the traditional land of the Ngintait nation. Upstream of the confluence of the Darling and Murray includes the land of the Barkindji and Maraura nations. The catchment contains many significant spiritual and cultural sites, including Lake Mungo in the Willandra Lakes Region.

European explorers first visited the lower Darling region in the 1820s and 1830s, searching for the ‘inland sea’. Their interactions with local Aboriginal groups were hostile and on occasions violent, leading to poor relations in years to come. Settlers followed the explorers and established large sheep grazing properties in the region. Many Aboriginal people were displaced or forcibly removed from their homeland as a result of European settlement. Wool production in the region thrived [AB1] in part due to river transport and trade system along the Darling River, peaking in the late 1800s when more than 40,000 bales of wool were shipped down the Darling each year.

The lower Darling region is sparsely populated and there are a few small towns in the catchment, including Menindee in the north of the catchment and Pooncarie in the south. The largest centre in the catchment, Wentworth, with a population of 2,500 (ABS 2011), is at the junction of the lower Darling and the River Murray. Larger regional centres outside the catchment, such as Broken Hill and Mildura, provide a greater range of services for residents of the lower Darling.

Land use in the catchment is largely based on pastoral industries, which comprise mainly sheep grazing for wool production but include beef cattle and goat farming as well. There are some small areas of lakebed cropping, and irrigated cropping, horticulture and viticulture. Tourism is also important to the local economy, with inland waterways providing good locations for fishing. National parks based on arid and wetland environments also attract tourists.

Regulation of water

In 1968, the naturally occurring chain of lakes near Menindee on the Darling River were modified by the NSW Government to improve its storage capacity for farming, recreation, mining, urban water supply and to manage Darling River floods. Consequently, the flows through the lower Darling River and the Great Darling Anabranch are highly regulated.

Overall, the average annual flow in the Darling River has been reduced by more than 40% as a result of water taken from the upper catchments of the Barwon–Darling river system. The timing of flows in the lower Darling has been changed, with the largest volume of water now flowing in summer to meet consumptive demand, rather than in autumn or spring when water flows from the north.

Environmental importance

The Menindee Lakes provide important waterbird habitat with more than 30 species of waterbirds recorded on the main lakes, including threatened species such as freckled duck and migratory waders. The lakes are listed in the Directory of Important Wetlands in Australia.

The Great Darling Anabranch and its associated lakes are an important ecological asset in the Basin. The lakes along the anabranch that are sometimes dry are the largest and most numerous ephemeral lakes in the Basin, and are highly significant in terms of their contribution to terrestrial and biodiversity value, because of their natural wetting and drying cycles, and diverse habitats. The lakes, also listed in the Directory of Important Wetlands in Australia, can provide refuge for wildlife during drought.

Kinchega National Park near Menindee includes 62 km of Darling River frontage and is one of only two large conservation areas along the river. It protects substantial areas of river red gums, and rare acacia and bluebush communities. Vegetation in the lower Darling consists largely of river red gum woodland in the riparian zone and immediate floodplain, and extensive areas of black box woodland with lignum and nitre goosefoot in the greater floodplain. Chenopod shrublands, which include saltbush and bluebush, dominate the lakebeds and alluvial floodplains of the Great Darling Anabranch.

Aquatic species in the lower Darling and the Great Darling Anabranch and associated tributaries and wetlands are part of an endangered ecological community and include 21 native fish species and hundreds of native invertebrate species within the Darling River. The lower Darling provides habitat for fish species such as the Murray cod and species under threat such as trout cod, Murray hardyhead, river snail, southern pygmy perch, silver perch and purple-spotted gudgeon.

In the Sustainable Rivers Audit (2012) the study area of Darling River Valley included the narrow upper valley of the Barwon–Darling river system, through to the wide floodplain regions of the mid and lower Darling River. The audit reported that the overall ecosystem health of the Darling Valley was poor. The fish community had lost half of its native species richness, and was rated poor in the lower and middle zones and moderate in the upper zone; while the macroinvertebrates were rated poor overall. Riverine vegetation was rated in good condition. There was little evidence of the main vegetation groups being cleared or damaged, however there were some modifications noted near the main river channels. The physical form of the river system was rated in moderate condition, but there was accelerated floodplain sedimentation in the upper zone and channel enlargements in the lower zone, since European settlement. The overall rating of hydrology of the Darling was moderate, as flow volumes, seasonality and variability has changed markedly in the main stem of the river system. However, there was little change from the reference condition for high over-bank floods and low or zero flows.

Water recovery

The Basin Plan sets Sustainable Diversion Limits, which is how much water can be used in the Murray–Darling Basin, while leaving enough water for the environment. A Sustainable Diversion Limit (SDL) was established for each catchment (or group of catchments) and the reduction in diversions required to achieve the SDL was identified.

The use of environmental water in a specific catchment or region will vary from year-to-year. The MDBA has a Basin-wide environmental watering strategy to guide the use of environmental water across the Murray–Darling Basin to help achieve the best possible results over the long term. Environmental water managers make the day-to-day decisions on what to water and when, in line with the strategy and taking into account seasonal conditions, priorities and the availability of environmental water. Watering decisions are made in consultation with various waterway managers and local landholders.

Catchment or regionally-specific details about environmental water use in the catchment including watering actions, portfolio details and planning, and monitoring of environmental watering, can be found through the Commonwealth Environmental Water Holder or the state government environmental water manager. 

More information

Water management

The management of the water resources is the responsibility of local, regional, state and Australian governments.

Delivery to households, industry and farms is managed by local councils, regional water authorities or state government.

State government departments for water also ensures that: the network of authorities manage water responsibly and fairly; catchment and waterway health is maintained or improved through catchment management authorities; and that water saving, re-use and flood management projects are implemented. State governments must manage their state’s water resources according to state and commonwealth water legislation.

In addition to directing operations of the regulated River Murray system, the MDBA implements a number of plans and programs to ensure the waters of the Basin, which flow through four states and one territory, are managed cohesively and in the best interests of all water users of the Basin. 

Rural water authority

Urban water authority

Catchment management authority

State government water manager

Use of environmental water

Irrigation water allocation

Maps

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