About the Basin

Environment | Storing and distributing water | Changes in the Basin | Managing the Basin

The Murray-Darling Basin is the catchment for the Murray and Darling Rivers and their many tributaries. Extending from north of Roma in Queensland to Goolwa in South Australia and including three quarters of New South Wales and half of Victoria it is the heartland and the economic powerhouse of rural Australia. It extends across one-seventh of the continent and has a population of nearly two million people. Another million people outside the region depend heavily upon its resources.

River Murray

The Murray-Darling Basin generates about 40 percent of the national income derived from agriculture and grazing. It supports one quarter of the nation's cattle herd, half of the sheep flock, half of the cropland and almost three-quarters of its irrigated land. The Basin contains more than twenty major rivers as well as important groundwater systems. It is also an important source of fresh water for domestic consumption, agricultural production and industry.

The Environment

Many of the Basin's natural resources are of high environmental value. Its wetlands are extensive and perform essential hydrological, biological and chemical functions, which support and maintain the productivity and health of the river systems. A number of these wetlands are recognised under the Convention on Wetlands of International Importance (otherwise known as the Ramsar Convention). These include Chowilla, Barmah-Millewa Forests, the Coorong, Gunbower Forest, Hattah-Kulkyne Lakes, the Kerang Wetlands, Lake Albacutya and the Macquarie Marshes.

Wetland Habitat

As a large, very shallow drainage basin covering more than one million square kilometres with only one exit flowing out of Lake Alexandrina in South Australia, the Murray-Darling Basin is an unusually complex biophysical system. Changing patterns of land use have groundwater impacts which are felt hundreds and even thousands of kilometres downstream.

For fish and other riverine life forms, the Murray-Darling Basin is a vast interconnected network, stretching from the saline lakes of the Coorong estuary, east to the alpine streams of the Snowy Mountains and north to the inland semi-arid and table land streams of southern Queensland. The network is now partly constricted by structures such as dams and locks which store water and regulate the rivers.

Storing and distributing water

Hume Weir

In the last 100 years life in the Murray-Darling Basin has been transformed by the construction of major water storages on the rivers. The total volume of water storage capacity in the Basin is just under 35,000 gigalitres. Of that, the Murray-Darling Basin Commission - with its major storages the Dartmouth, Hume, Lake Victoria and the Menindee Lakes and other river regulatory structures - is responsible for about a third. These storages have made it possible to store water during wet periods and release it as needed during summer or in droughts. The water is shared between Victoria, New South Wales and South Australia using principles agreed under the Murray-Darling Basin Agreement (see Whose water is it?). Security of water supply through entitlements under the Agreement has facilitated substantial agricultural development along the River Murray system.

Changes in the Basin

The development that made the economic productivity of the Basin possible has also caused many biophysical changes. Some of these changes have reduced biodiversity and threaten the potential of economic production in the future. In the south many rivers now have low flows in winter and spring when rain in their catchments is being captured in the storages. In the summer and autumn when flows were traditionally low, they run full to supply the irrigation regions.

Degraded Land

The operation of the storages and the extraction of large volumes of water for consumption off-stream have also reduced the annual and seasonal variability which shaped the ecology of the region.

Beyond the riverine corridors extensive clearing of native vegetation has dramatically increased the volumes of rainwater leaking through the soil profile to groundwater systems. Groundwater levels are now rising in many parts of the Basin causing widespread and serious salinity problems. Broad-scale clearing has also reduced the habitat for many native plant and animal species.

Managing the Basin

Rice Irrigation

Management of the Murray-Darling Basin requires the balancing of many values and assets that are potentially in competition. Tensions exist between some production-orientated activities and environmental needs. There is also competition between different economic interests. To help resolve these issues a framework for political and administrative cooperation has been created, initially with a focus just on the water resources of the River Murray and lower Darling.

In 1917 the River Murray Commission was set up to manage water distribution between the three southern Basin States, New South Wales, Victoria and South Australia, according to an agreement that they had approved in 1914. Later, growing awareness of increasing salinity problems focussed attention on the need to take account of processes occurring in the water catchment and so the Murray-Darling Basin Ministerial Council and the Murray-Darling Basin Commission were established in 1986 and 1988 respectively. These organisations are advised by the Ministerial Council's Community Advisory Committee. Their primary task is to ensure the Murray-Darling Basin is managed for the benefit of current and future generations. Since their inception, the Ministerial Council and Commission have developed and will continue to implement and refine policies, strategies and programs to address key natural resource management issues affecting the health of the Basin.