Snapshot
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Catchment area
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9% of the Murray–Darling Basin
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Contribution to Basin water
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–
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Annual stream flow
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–
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River length
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2,500 km total, approx. 1,000 km Wentworth to Southern Ocean
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Major tributaries
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Darling River, Great Darling Anabranch, Rufus River, Chowilla Creek, Pike River, Katarapko Creek, Marne River, Saunders Creek, Bremer River, Finnis River
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Major distributaries
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Frenchmans Creek, Pukah Creek, Lindsay River, Salt Creek, Mundic Creek, Katarapko Creek
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Major towns/cities
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Renmark, Waikerie, Murray Bridge
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Major water storages
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Lake Victoria (677 GL)
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Key water users
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Irrigated agriculture, urban centres (including Adelaide), stock and domestic supply
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Summary
The River Murray is Australia's longest river, running a course of 2,500 km from near Mount Kosciuszko in the Australian Alps to the Southern Ocean at Goolwa, in South Australia. The catchment description of the River Murray is split into 3 sections – upper, central and lower.
The lower River Murray catchment takes in the country from the confluence of the River Murray and the Darling River at Wentworth, New South Wales, to the Murray Mouth at Goolwa, in South Australia. The river flows through a large semi-arid region that makes up about 9% of the area of the Basin.
In its lower catchment, the River Murray flows through semi-arid mallee country, where the only substantial water source is the river itself. The region contains many significant wetlands including the Riverland wetland (and the Chowilla Floodplain), and lakes Alexandrina and Albert and the Coorong at the Murray Mouth.
Much of the lower Murray catchment is sparsely populated, with pastoral grazing holdings to the north and large dryland cropping enterprises to the south. The Riverland, from Renmark to Morgan, is highly developed with several medium-sized towns established on the banks of the River Murray. These centres support a diverse horticultural industry, as well as dryland agriculture within the region. Tourism based around the river environment and water activities is also important to the regional economy.
The landscape and its water
The lower Murray catchment begins in the mallee country of north-west Victoria and western New South Wales, and extends into the South Australian mallee. The landscape of gently rolling sand hills is named after the small, multi-stemmed eucalypt – the mallee – which is the main type of tree throughout the region. The River Murray cuts a winding westerly course through the mallee until Morgan in South Australia. Large floodplains have developed along the river's path.
At Morgan, the river turns south and flows for about 200 km through a limestone gorge, to Mannum. Beyond the limestone gorge, the Murray commences the last leg of its journey towards the ocean, flowing winding past Murray Bridge and Tailem Bend. In this reach, several creeks and rivers flow in from the eastern Mount Lofty Ranges. The Murray flows into Lake Alexandrina, which supplies Lake Albert to its east, and out to the Southern Ocean, through the Murray Mouth estuary.
An important part of the Murray Mouth region, although not connected to the Murray, is the Coorong, which is a long, shallow, brackish to hypersaline lagoon, more than 100 km in length. The Coorong is separated from the Southern Ocean by a narrow sand dune peninsula. The saline waters of the Coorong and the Murray Mouth Estuary are prevented from entering the lakes and the River Murray by a series of barrages built in the 1930s along the seaward margins of Lake Alexandrina.
Groundwater is found in extensive alluvial groundwater systems throughout the lower Murray catchment. Surface water and groundwater systems in the catchment are highly connected, and the River Murray tends to gain water from the groundwater system in this part the catchment. Water quality varies between aquifers, and many aquifers, particularly near the River Murray, are highly saline. Salt interception schemes along the River Murray, particularly in the Sunraysia area and between Waikerie and Renmark in the Riverland, pump saline groundwater away from the river to disposal basins.
People, industry and water use
The River Murray flows through the traditional land of many First Nations, and the river and its floodplains have long been important for sustenance and spirituality. The First Nations people associated with land around the confluence of the Darling and Murray rivers include the Barkindji, Maraura, Muthi Muthi and Nyeri Nyeri. Along the River Murray, from about Mildura and into South Australia is also the traditional land of the Ngintait Nation. The land of the lower reaches of the Murray, the Lakes and the Coorong is the traditional land of the Ngarrindjeri nation. The land west of the river and including the Mount Lofty Ranges, includes the country of the Kaurna and Peramanok Nations.
The lower River Murray takes a course through semi-arid country that is sparsely populated. There are small remote communities in the vicinity of the Murray's junction with the Darling in western New South Wales. Wentworth is the largest town in the east of the lower Murray catchment, with 2,500 people (ABS 2011). The development of irrigation in the Riverland led to the establishment of a number of small but vibrant centres including, Renmark, Berri, Loxton, Waikerie and Barmera. The population of the region is about 40,000 people. Murray Bridge, with a population of about 14,000, is a large agricultural and regional service centre, which was established on the lower reaches of the river.
Land use varies across the lower catchment, ranging from grazing of extensive semi-arid plains and cereal cropping in the mallee country of Victoria and South Australia; to irrigated horticulture in the Riverland, where a wide range of horticultural crops is grown, including citrus, wine grapes, olives, almonds, walnuts, pistachios, stone fruit, avocado and vegetables. On the floodplains before the river enters Lake Alexandrina, the river flats are irrigated for dairying.
Less than 20% of the land in the lower catchment is native vegetation, comprising public land, such as national parks and state reserves, and private conservation land.
Recreation and tourism activity provide substantial income for the region. The lower Murray catchment attracts visitors to the region based on water sports, fishing, camping, bushwalking, house boating, historic paddle-steamers, and enjoyment of locally-produced wine and food. Wetlands and national parks in the region are also an attraction.
The 2008 water availability in the Murray report by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) was based on the whole Murray catchment, from the mountain headwaters to the Murray Mouth, as well as the lower Darling River catchment, below Menindee. Average annual water use in the region was reported as high, with 36% of available water in the Basin. Water use includes diversion for the major irrigation areas of the Murray valley, northern Victoria, Sunraysia and the Riverland, as well diversion for large urban centres such as Albury–Wodonga, Yarrawonga, Mildura, Murray Bridge, Adelaide and regional centres in South Australia. The Murray region accounts for 11% of total groundwater use in the Basin, with most use occurring in the central and lower River Murray catchment. Groundwater use represented 5–8% of total water use in the reporting region.
Regulation of water in the catchment
The water resources of the River Murray are regulated from the mountains to the sea, to provide water for hydro-electric power generation, urban centres, irrigated agriculture and the environment, throughout the entire river valley (and beyond).
Irrigation development along the Murray commenced in the 1890s. The River Murray Waters Agreement in 1914, which took 13 years to negotiate, was the first of successive water sharing arrangements between the Basin states – South Australian, Victoria, New South Wales, Queensland and the Australian Capital Territory – and the Commonwealth. The Murray–Darling Basin Authority (MDBA) is the agency responsible for administering current intergovernmental agreements and legislation relating to the River Murray.
Weirs and dams were constructed along the River Murray throughout the 1900s to regulate water flow and service irrigation areas. Torrumbarry Weir (37 gigalitres (GL)) downstream of Echuca was constructed in 1924, Hume Dam near Albury was constructed in 1928 and then expanded in 1961 (3,038 GL), and Yarrawonga Weir (118 GL) was constructed in 1939.
Lake Victoria (677 GL), located 60 km downstream of the confluence of the Murray and Darling rivers, in far-west New South Wales, was constructed in 1925 around natural wetlands. River flows from the central catchment are captured in Lake Victoria to facilitate and regulate flows to South Australia.
The Menindee Lakes storage was constructed on the Darling River in 1968, around ephemeral lakes and associated wetlands, with a capacity of 2,050 GL. Water from Menindee Lakes is used to manage and augment supplies to the lower Murray system.
Dartmouth Dam (3,096 GL) on the Mitta Mitta River was constructed in 1979 to augment water supplies to the Hume Dam and the Murray catchment, and enable further irrigation development.
The Snowy Mountains Hydro-electric Scheme impounded water from several rivers (Snowy, Eucumbene, upper Murrumbidgee and Tooma), which is redirected through tunnels to power generation plants. Water that passes through the Murray power stations via the Geehi Reservoir and Swampy Plain River adds an additional 900 GL of flow to the Murray system. Khancoban Pondage (21 GL), at the end of the Swampy Plain River, stores water from the hydro-electric scheme and subsequently releases it in response to demand for water for irrigation and urban use. Water from the Tooma Reservoir is transferred out of the Murray catchment to the Tumut River, in the Murrumbidgee catchment.
Along the length of the River Murray, water is also pumped directly from the river or diverted through small weirs to secure water for individual properties.
Water management in the Murray catchment is complex and managed by the MDBA. Water is released from Hume Dam, the Menindee Lakes and Lake Victoria to meet daily demand of urban centres (including Adelaide) and irrigators. Water for the lower Murray is preferentially released from the Menindee Lakes and Lake Victoria rather than upstream storages, to minimise river conveyance losses and minimise evaporation losses. Water is preferentially stored in Dartmouth Dam due to its low evaporation losses compared with other storages. Water is transferred from Dartmouth Dam to Hume Dam, as required, to meet forecast demand.
End-of-river flows are captured in Lake Alexandrina and Lake Albert and releases are made to the Southern Ocean via the operation of a series of barrages.
Water delivery for consumptive or environmental use has to take into account a number of constraints in the system. Daily transfer of water from Dartmouth Dam to Hume Dam is limited to around 10 GL per day, flows between Hume Dam and Lake Mulwala is limited to 25 GL per day, and flows downstream of Yarrawonga Weir through the Barmah Choke are limited to 10 GL per day, even with regulators in place, to prevent unseasonal flooding of the Barmah–Millewa Forest. The channel system of Murray Irrigation Limited, in the New South Wales Riverina, may be used to bypass this section of river and augment river flows to meet downstream water demand.
Travel time of water is another important water management consideration. It can take 4 weeks for water to travel between upper catchment storages and the lower Murray. This has a significant influence on system operations, especially when management decisions need to be made well in advance of the range of meteorological forecasts.
Environmental importance
It is important that water quality in the lower River Murray is maintained for the environment and for populations living in the lower Murray catchment, by adequate volumes of flow according to a planned regime. This means that water released from Hume Dam is triggered by dam inflows, so that the river flows reflect natural seasonal conditions. Adequate flows are essential to export salt from the river system.
The lower River Murray hosts many wetlands and riverine ecosystems, several of which are nationally and internationally significant. The Riverland Ramsar site follows the river and its floodplain for an 80 km stretch east of Renmark. The site includes creeks, channels, lagoons, billabongs, swamps and lakes, which become flooded when river levels are high. Two important features of the area are the Chowilla Floodplain and Lindsay–Wallpolla Islands, which contain plants and animals of state and national significance, and waterbirds protected under international migratory bird agreements.
The Coorong, and Lakes Alexandrina and Albert Wetland at the end of the river system are also Ramsar listed. There are 23 wetland types at the site, including estuarine waters, coastal brackish/saline lagoons, permanent freshwater lakes, permanent freshwater marshes, and seasonally flooded agricultural land. The area supports a diverse range of plant, waterbird and fish species and communities. The Ngarrindjeri people, local to the area, have a strong spiritual and cultural connection to the land, and there are many traditional and archaeological sites.
The Sustainable Rivers Audit 2 (released in 2012) reported the overall ecosystem health of the lower River Murray valley was poor. In this report, the lower Murray region extends from the junction of the Murray and Darling rivers at Wentworth, to where the river enters Lake Alexandrina, Lake Albert and the Coorong, near the Murray Mouth.
Flow regulation had severely affected species abundance and diversity of fish, with the health of the fish community being rated poor. The macroinvertebrate community was rated in moderate condition. Riverine vegetation was rated poor condition overall, however vegetation in the upper and middle zones of the lower Murray valley was rated good in riparian and floodplain environments, but in the Mount Lofty and lower zones of the valley, vegetation was rated extremely poor. The physical form of the river was rated moderate condition but elevated sediment loads since European settlement has resulted in sedimentation within the river channel and there was evidence of channel simplification. Flow seasonality and variability was rated very poor in the valley, overall, especially in the upper, middle and lower zones of the valley, where river flows are impacted by seasonality of supply for urban centres and irrigation. The hydrology of the Mount Lofty zone was rated good.
Water recovery
The Basin Plan specifies how much water is required to satisfactorily manage environmental sites and functions in the Murray–Darling Basin. 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.
In South Australia, there are 4 surface water SDL units and only 1 requires a reduction in diversions to achieve its SDL. For the South Australia Murray surface water unit, the baseline diversion level of surface water determined by the Basin Plan is 665 GL per year. The required local reduction in take, to achieve an environmentally sustainable level of diversion is 101 GL per year.
In addition to the 'local reduction' for each surface water unit, a further 971 GL per year is to be recovered from all southern Basin catchments (the southern zone 'shared reduction') to meet the needs of the whole Murray system.
Groundwater extractions and/or entitlements determined by the Basin Plan matched or were considerably less than the sustainable diversion limits set for the groundwater units in the lower Murray catchment in South Australia. For locally-specific detail, water users should consult regional water sharing plans developed by state government water departments.
Further information on water recovery in the Murray–Darling Basin, which includes an interactive map with catchment-specific information, is available at water recovery progress.
The Basin Plan allows for adjustments to SDLs if new works or changes in river operation and management rules increase the quantity of water available to be extracted, or efficiency measures through infrastructure works and upgrades reduce the quantity of water required in a delivery system.
The use of environmental water in a specific catchment or region will vary from year-to-year. The MDBA has produced 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 Office or the state government environmental water manager (see table below).
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 or regional water authorities.
State government departments for water ensures the network of authorities manages water responsibly and fairly, that 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 4 states and 1 territory, are managed cohesively and in the best interests of all water users of the Basin. Such programs include:
Useful links
