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Murray-Darling basin
Aerial view of the Darling River.jpg
An aerial view of the Darling River near Menindee in the Far West of the basin in New South Wales
Murray-catchment-map MJC02.png
Map of the Murray–Darling basin
Length 3,375 km (2,097 mi)
Area 1,061,469 km2 (409,835 sq mi)
Geography
Country Australia
States and
territories
Rivers

The Murray–Darling basin is a large geographical area in the interior of southeastern Australia, encompassing the drainage basin of the tributaries of the Murray River, Australia's longest river, and the Darling River, a right tributary of the Murray and Australia's third-longest river. The basin, which includes six of Australia's seven longest rivers and covers around one-seventh of the Australian landmass, is one of the country's most significant agricultural areas. Located west of the Great Dividing Range, it drains southwestly into the Great Australian Bight and spans most of the states of New South Wales and Victoria, the Australian Capital Territory, and parts of the states of Queensland (the lower third) and South Australia (the southeastern corner).

The basin is 3,375 kilometres (2,097 mi) in length, with the Murray River being 2,508 km (1,558 mi) long. Most of the 1,061,469 km2 (409,835 sq mi) basin is flat, low-lying and far inland, and receives little direct rainfall. The many rivers it contains tend to be long and slow-flowing, and carry a volume of water that is large only by Australian standards.

The Snowy Mountains Scheme provides some security of water flows to the Murray–Darling basin, providing approximately 2,100 gigalitres (7.4×1010 cu ft) of water a year to the basin for use in Australia's irrigated agriculture industry, which is worth about A$3 billion per annum, representing more than 40% of the gross value of the nation's agricultural production.

The original inhabitants

The basin was once home to a large number of Aboriginal people whose traditional lifestyle and cultures were gradually altered by the arrival of Europeans, while others were outright killed by the settlers. Although some tribes organised resistance, such as the Maraura, whose territory lay around the Rufus River above Renmark and the Tanganekald near The Coorong, they were eventually either killed, exiled, or succumbed to disease.

Native fauna

The Murray–Darling basin is home to many native animal species. The true numbers may not be known, but a fairly confident estimate has been made of these animals and the current status of their population. Among the aboriginal fauna in the region, the study found that there were:

  • 80 species of mammals, with 62 extinct and 10 endangered
  • 55 species of frogs, with 18 endangered
  • 46 species of snakes, with five endangered
  • five species of turtles, with none endangered
  • 34 species of fish, with up to half of them either threatened or of conservation significance

Historical records show that the previous abundances of fish provided a reliable food source. The bountiful fish became concentrated when the early stages of a flood left shallow water across the floodplain. Today, roughly 24 native freshwater fish and another 15-25 marine and estuarine species are existent in the basin, a very low biodiversity.

2018–2019 fish kill

Over Christmas 2018 and January 2019 there were two mass deaths of fish in the waters of the basin, the first numbering 10,000, the second in the 100,000s. Species affected were Murray cod, golden perch, silver perch and bony herring. Some blamed the draining of water from the Menindee Lakes by WaterNSW, with only 2.5% of the original water volume in the lakes being left; after the first fish kill, both the Department of Primary Industries (DPI) and WaterNSW blamed the ongoing drought affecting Australia, while the DPI blamed the second kill on a disruption of an algal bloom caused by falling temperature.

Introduced species

Four varieties of carp were used to stock up fish dams. Since then they have made their way into the river systems, where they spread quite quickly. Human introduction, possibly by anglers using small carp illegally as live bait, has also increased their distribution. These fish are very mobile, breed rapidly and can survive in very shallow water and through long periods of very low dissolved oxygen content.

Carp are a problem because they feed by sucking gravel from the riverbed and taking all the edible material off it, before returning the rest to the water. This stirs up all the sediment, reducing the quality of the water. A project for developing daughterless carp shows promise for eliminating carp from the river system.

Cane toads have entered the upper reaches of the Darling Basin and there are several reports of individuals being found further down the system. Cane toads compete with native amphibians and are toxic to native carnivores.

Physiography

This area is one of the physiographic provinces of the larger East Australian basins division, and encompasses the smaller Naracoorte Platform and Encounter Shelf physiographic sections.

Total water flow in the Murray–Darling basin 1885 to the present has averaged around 24,000 gigalitres (24,000 hm3; 19,000,000 acre⋅ft) per year. This is the lowest rate of the world's major river systems. About 6.0 percent of Australia's total rainwater falls into the basin. In most years only half of this quantity reaches the sea and in dry years much less. Estimated total annual flows for the basin have ranged from 5,000 gigalitres (5,000 hm3; 4,100,000 acre⋅ft) in 1902 to 57,000 gigalitres (57,000 hm3; 46,000,000 acre⋅ft) in 1956. Despite the magnitude of the basin, the hydrology of the streams within it is quite varied.

These waters are divided into four types:

  • The Darling and Lachlan basins. These have extremely variable flows from year to year, with the smallest annual flow being typically as little as 1 percent of the long-term mean and the largest often more than ten times the mean. Periods of zero flow in most rivers can extend to months and in the drier parts (Warrego, Paroo and Lower Darling basins) to years. Flows in these rivers are not strongly seasonal. In the northern regions the majority of floods occur in the summer from monsoonal penetration. For most of the Darling and Lachlan catchments it is typical to see high or low flows begin in winter and extend to the following autumn (see El Niño). High water extraction rates for irrigation and mining have heavily compromised these rivers.
  • The southwestern basins (Campaspe, Loddon, Avoca, Wimmera). These have a marked winter rainfall maximum and relatively lower precipitation variability than the Lachlan or Darling. However, the age and infertility of the soils mean that run-off ratios are exceedingly low (for comparison, around a tenth that of a European or North American catchment with a similar climate). Thus, variability of runoff is very high and most of the terminal lakes found in these basins very frequently dry up. Almost all runoff occurs in the winter and spring and, in the absence of large dams for regulation, these rivers are often seasonally dry during summer and autumn.
  • A number of small catchments in South Australia, of which the largest are the Angas River flowing through Strathalbyn and the Finniss River further west, are part of the Murray–Darling Basin. These catchments lead to Lake Alexandrina, one of the lakes at the end of the Murray system. The Angas River is often dry in summer because of high levels of water extraction. The Finniss River has permanent flow into Lake Alexandrina but was cut off by a weir for several years of drought in the early 21st century.
  • The Murray, Murrumbidgee and Goulburn (except the Broken River which resembles the southwestern basins) Basins. Because these catchments have headwaters in alpine country with relatively young peaty soils, the runoff ratios are much higher than in other parts of the basin. Consequently, although gross precipitation variability is no lower than in the Lachlan or Darling basins, runoff variability is markedly lower than in other parts of the basin. Typically these rivers never cease to flow and the smallest annual flow is around 30 percent of the long-term mean and the largest around three times the mean. In most cases the flow peaks very strongly with the spring snow melt and troughs in mid-autumn.

The two principal rivers of the basin, the Murray and Darling, bring water from the high ranges of the east and carry it west then south through long flat and dry inland areas, often resulting in alluvial channel wetlands, such as The (Great) Cumbung Swamp, at the terminus of the Lachlan and Murrumbidgee Rivers. Nevertheless, these waters are subject to major diversions for municipal drinking supplies and irrigated agriculture that began in the 1890s. Currently, 4 major reservoirs, 14 lock and weir structures, and five coastal barrages interject the water flowing down the Murray-Darling. Of the approximately 13,000 gigalitres (13,000 hm3; 10,500,000 acre⋅ft) of flow in the basin, which studies have shown to be divertible, 11,500 gigalitres (11,500 hm3; 9,320,000 acre⋅ft) are removed for irrigation, industrial use, and domestic supply. Agricultural irrigation accounts for about 95 percent of the water removed, including for the growing of rice and cotton. This extraction is highly controversial among scientists in Australia, regarding the agriculture industry's high water use in a region extremely short of water (as much due to exceptionally low run-off coefficients as to low rainfall). These extensive irrigation systems require a reliable supply of water, not the unpredictable flows that characterise the Murray-Darling. These structures and irrigation implements were ideal when there was a steady flow of water. However, during "the Big Dry", as the early 2000s drought came to be known, Australian farmers experienced a scarcity unlike ever before. The drought was so severe that numerous rivers and streams such as the Murray-Darling stopped flowing. The basin contains more than 30,000 wetlands. Eleven of these are protected under the Ramsar Convention of Wetlands of International Importance.

Rivers in the Murray–Darling basin

The rivers listed below comprise the Murray–Darling basin and its direct significant tributaries, with elevations of their confluence with the downstream river. The tributary with the highest elevation is Swampy Plain River that rises in the Snowy Mountains, below Mount Kosciuszko at an elevation of 2,120 metres (6,960 ft), and ends merging with the Murray River, descending 1,860 metres (6,100 ft).

The ordering of the basin, from downstream to upstream, is:

Rivers of the Murray–Darling basin
Catchment river Elevation at
confluence		 River mouth States River length
Tributary
Tributary
Tributary
Tributary
Tributary
Tributary m ft km mi
Murray River 0 0 Southern Ocean NSW, Vic, SA 2,375 1,476
Darling River 35 115 Murray NSW 1,472 915
Paroo River 94 308 Darling Qld, NSW 1,210 750
Warrego River 98 322 Darling Qld, NSW 1,380 860
Langlo River 280 920 Warrego Qld 440 270
Nive River 336 1,102 Warrego Qld 263 163
Culgoa River 109 358 Darling Qld, NSW 489 304
Birrie River 115 377 Culgoa Qld 197 122
Barwon River (New South Wales) 110 360 Darling NSW 700 430
Bokhara River 113 371 Barwon Qld, NSW 347 216
Namoi River 130 430 Barwon NSW 708 440
Mooki River 264 866 Namoi NSW 128 80
Peel River (New South Wales) 286 938 Namoi NSW 210 130
Cockburn River 384 1,260 Peel NSW 34 21
Manilla River 349 1,145 Namoi NSW 138 86
Macdonald River (Bendemeer) 705 2,313 Namoi NSW 169 105
Cobrabald River 990 3,250 Macdonald NSW 53 33
Gwydir River 144 472 Barwon NSW 488 303
Horton River 270 890 Gwydir NSW 128 80
Moredun Creek 645 2,116 Gwydir NSW 210 130
Rocky River (New South Wales) 760 2,490 Gwydir NSW 138 86
Mehi River 145 476 Barwon NSW 314 195
Moonie River 149 489 Barwon NSW 542 337
Boomi River 152 499 Barwon NSW, Qld 231 144
Macquarie River 154 505 Barwon NSW 960 600
Castlereagh River 121 397 Macquarie NSW 541 336
Talbragar River 258 846 Macquarie NSW 277 172
Coolaburragundy River 271 889 Talbragar NSW 156 97
Little River (Dubbo) 271 889 Macquarie NSW 122 76
Bell River (New South Wales) 285 935 Macquarie NSW 146 91
Cudgegong River 342 1,122 Macquarie NSW 250 160
Turon River 406 1,332 Macquarie NSW 117 73
Crudine River 563 1,847 Turon NSW 54 34
Fish River (New South Wales) 668 2,192 Macquarie NSW 119 74
Campbells River 706 2,316 Fish NSW 82 51
Duckmaloi River 1,010 3,310 Fish NSW 27 17
Weir River (Queensland) 166 545 Barwon Qld, NSW 197 122
Balonne River 171 561 Barwon Qld 479 298
Maranoa River 207 679 Balonne Qld 519 322
Merivale River 401 1,316 Maranoa Qld 205 127
Condamine River 256 840 Balonne Qld 657 408
Macintyre River 224 735 Barwon NSW, Qld 319 198
Dumaresq River 227 745 Macintyre NSW 214 133
Macintyre Brook 241 791 Dumaresq Qld 165 103
Beardy River 354 1,161 Dumaresq NSW 90 56
Pike Creek (Queensland) 360 1,180 Dumaresq Qld 117 73
Mole River (New South Wales) 363 1,191 Dumaresq Qld 73 45
Deepwater River 601 1,972 Mole NSW 84 52
Bluff River (New South Wales) 614 2,014 Mole NSW 13 8.1
Severn River (Queensland) 375 1,230 Dumaresq Qld, NSW 90 56
Severn River (New South Wales) 284 932 Macintyre NSW 52 32
Beardy Waters 884 2,900 Severn (NSW) NSW 70 43
Bogan River 111 364 Darling NSW 617 383
Little River (Parkes) 305 1,001 Bogan NSW 319 198
Murrumbidgee River 55 180 Murray NSW, ACT 1,488 925
Lachlan River 68 223 Murrumbidgee NSW 1,440 890
Belubula River 262 860 Lachlan NSW 165 103
Boorowa River 301 988 Lachlan NSW 134 83
Abercrombie River 375 1,230 Lachlan NSW 130 81
Isabella River (New South Wales) 479 1,572 Abercrombie NSW 51 32
Bolong River 589 1,932 Abercrombie NSW 60 37
Tumut River 220 720 Murrumbidgee NSW 182 113
Goobarragandra River 272 892 Tumut NSW 56 35
Doubtful Creek 1,290 4,230 Tumut NSW 15 9.3
Yass River 345 1,132 Murrumbidgee NSW 139 86
Goodradigbee River 345 1,132 Murrumbidgee NSW 105 65
Crookwell River 430 1,410 Murrumbidgee NSW 78 48
Molonglo River 440 1,440 Murrumbidgee NSW, ACT 115 71
Jerrabomberra Creek 554 1,818 Molonglo NSW, ACT 35 22
Sullivans Creek 556 1,824 Molonglo NSW, ACT 13 8.1
Queanbeyan River 567 1,860 Molonglo NSW, ACT 104 65
Cotter River 460 1,510 Murrumbidgee ACT 74 46
Paddys River (Australian Capital Territory) 477 1,565 Cotter ACT 28 17
Tidbinbilla River 618 2,028 Paddys ACT 13 8.1
Gibraltar Creek 647 2,123 Paddys ACT 13 8.1
Gudgenby River 573 1,880 Murrumbidgee ACT 35 22
Naas River 631 2,070 Gudgenby ACT 26 16
Orroral River 842 2,762 Gudgenby ACT 15 9.3
Bredbo River 695 2,280 Murrumbidgee NSW 52 32
Strike-a-Light River 733 2,405 Bredbo NSW 38 24
Numeralla River 706 2,316 Murrumbidgee NSW 94 58
Big Badja River 735 2,411 Numeralla NSW 32 20
Kybeyan River 745 2,444 Numeralla NSW 36 22
Wakool River 58 190 Murray NSW 363 226
Niemur River 63 207 Wakool NSW 155 96
Edward River (an anabranch) 61 200 Murray NSW 383 238
Little Murray River (Victoria) 67 220 Murray Vic 46 29
Loddon River 71 233 Murray Vic 392 244
Avoca River 74 243 Murray Vic 270 170
Little Murray River (New South Wales) 75 246 Murray NSW 22 14
Goulburn River, Victoria 100 330 Murray Vic 654 406
Broken River (Victoria) 118 387 Goulburn Vic 225 140
Yea River 162 531 Goulburn Vic 122 76
Murrindindi River 186 610 Yea Vic 26 16
Acheron River 190 620 Goulburn Vic 84 52
Little River (Cathedral Range) 207 679 Acheron Vic 22 14
Steavenson River 264 866 Acheron Vic 20 12
Taggerty River 368 1,207 Steavenson Vic 18 11
Rubicon River 200 660 Goulburn Vic 43 27
Royston River 381 1,250 Rubicon Vic 19 12
Big River (Goulburn River, Victoria) 259 850 Goulburn Vic 62 39
Delatite River 260 850 Goulburn Vic 83 52
Howqua River 265 869 Goulburn Vic 66 41
Jamieson River 294 965 Goulburn Vic 33 21
Campaspe River 123 404 Murray Vic 232 144
Coliban River 183 600 Campaspe Vic 89 55
Little Coliban River 501 1,644 Coliban Vic 12 7.5
Ovens River 125 410 Murray Vic 191 119
King River, Victoria 142 466 Ovens Vic 126 78
Buffalo River (Australia) 206 676 Ovens Vic 65 40
Dandongadale River 279 915 Buffalo Vic 41 25
Catherine River (Victoria) 392 1,286 Buffalo Vic 25 16
Buckland River (Victoria) 274 899 Ovens Vic 38 24
Kiewa River 156 512 Murray Vic, NSW 109 68
Mitta Mitta River 180 590 Murray Vic 204 127
Dart River (Victoria) 452 1,483 Mitta Mitta Vic 29 18
Big River (Mitta Mitta River, Victoria) 655 2,149 Mitta Mitta Vic 52 32
Cobungra River 656 2,152 Mitta Mitta Vic 55 34
Victoria River (Victoria) 830 2,720 Cobungra Vic 25 16
Tooma River 238 781 Murray NSW 74 46
Swampy Plain River 269 883 Murray NSW, Vic 59 37
Geehi River 439 1,440 Swampy Plain Vic 47 29

Murray-Darling Basin Initiative

Background

The basin affects five states and territory governments, which according to the Constitution, are responsible for managing water resources. The River Murray Commission was established in 1917. Under the River Murray Waters Agreement, which did not include Queensland though about a quarter of the basin lays in the state, the Commission was an advisory body with no authority for enforcement of provisions. For a long time the Commission was only concerned with water quantity until salinity became a problem. This led to minor reforms in 1982 in which water quality became part of the Commission's responsibilities.

However, it was soon recognised that a new organisational structure which considered the national perspective was needed for effective management. The Murray–Darling Basin Agreement was first adopted in 1985 but it wasn't until 1993 that its full legal status was enacted. The Agreement led to the creation of a number of new organisations under what is known as the Murray-Darling Basin Initiative. These included the Murray-Darling Basin Ministerial Council and the Murray Darling Basin Commission.

Murray–Darling Basin Plan

The Murray–Darling Basin Authority (MDBA) was formed in 2008 to manage the Murray–Darling basin in an integrated and sustainable manner, in conjunction with the Basin states. The MDBA is responsible for preparing and overseeing a legally-enforceable management plan. In October 2010, MDBA released a draft Murray-Darling Basin Plan (MDBP) for consultation. After a difficult consultation process, on 22 November 2012, Tony Burke, Minister for Sustainability, Environment, Water, Population and Communities, signed the Murray-Darling Basin Plan, which passed the Australian Parliament's disallowance period on 19 March 2013.

Community consultation

The MDBA's draft Murray-Darling Basin Plan, titled the Guide to the Proposed Murray–Darling Basin Plan, was released in October 2010 as the first part of a three-stage process to address the problems of the Murray–Darling basin. The Plan was in response to the 2000s Australian drought, and designed to secure the long-term ecological health of the Murray–Darling basin. This entailed cutting existing water allocations and tree growth environmental flows. The Basin Plan was designed to set environmentally sustainable limits on the quantities of water that may be taken from Basin water resources, to set Basin-wide environmental, water quality and salinity objectives, to develop efficient water trading regimes across the Basin, to set requirements for state water resource plans and to improve water security for all Basin users. It also intends to minimise social and economic impacts whilst achieving the plan's environmental outcomes.

With the release of the Guide to the Proposed Murray–Darling Basin Plan there have been a number of protests and voiced concerns about the plan in rural towns that the MDBA visited to present the plan to consultation meetings. More than 5,000 people attended a MDBA meeting in Griffith where Griffith Mayor, Mike Neville, said the plan would "obliterate" Murrumbidgee valley communities. Other groups also echo this feeling, such as the Victorian Farmers Federation and Wine Group Growers' Australia. Conversely, support for the Murray–Darling Basin plan has been received by various groups, including Australian Conservation Foundation, and Environment Victoria.

New legal advice from Commonwealth government lawyers is changing the plan. The Government's interpretation is that the plan must give equal weight to the environmental, social, and economic impacts of proposed cuts to irrigation.

Environmentalists and South Australian irrigators, at the end of the river in South Australia, say that the authority should stick to its original figure.

In October 2010, a parliamentary inquiry into the economic impacts of the plan was announced.

In late October 2010 the Water Minister, Tony Burke, played down the prospect of a High Court challenge to the Murray–Darling Basin plan, as confusion continued over new legal advice released by the Government. In response to community concerns that MDBA had put environmental issues first over social and economic needs, Burke released new advice on the requirements of the Water Act. Burke stated that the Act does allow for the authority to "optimise" the needs of all three areas, but constitutional lawyer, George Williams, had cast doubts over the interpretation of the laws, stating it could be subject to a legal challenge.

The MDBA announced in November 2010 that it might be forced to push back the release of its final plan for the river system until early 2012.

The then MDBA chairman, Mike Taylor, reassured the public meeting that more work is being done to look at how the proposed cuts would affect regional communities. He stated: "Importantly, we want to make sure the social and economic impacts—which under any sort of scenario is very significant—were fully teased out". Taylor resigned as he allegedly believed that the overriding principle should be the environmental outcome which was in conflict with the Gillard Government and following a period of sustained criticism of the Authority and the implementation of the proposed draft basin plan. He was replaced by former New South Wales Planning Minister, Craig Knowles.

In late May 2012, the revised plan was forwarded to state water ministers. It did not alter the recommendation to cut 2,750 gigalitres (2.75 km3; 2,230,000 acre⋅ft) of water entitlements.

Following much negotiation between the Commonwealth and State governments and numerous submissions from interested stakeholders and the community, the Basin Plan became law in November 2012 and can now be implemented.

Sustainability and risks

Although the Murray-Darling Basin Plan (MDBP) is a step towards sustainability the measures keep a significant risk of human activities exacerbating the drought risk (see River Murray which has only dried up twice since records began). The Environmental Water Requirement found that a reduction in allocations of 7,600 GL (7.60 km3; 6,160,000 acre⋅ft) (per year) is required to be certain that the river systems would maintain their health. However objectors cite socio-economic impacts of major cutbacks to the widescale farming (and in some areas wine-growing) in the basin, and conclude that within plans for population growth, particularly in times of drought, may be a need for sustainable water transportation from new extraction from rivers in the wettest part of the country, the Cape York Peninsula or more desalination.

See also

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