Managing the system
The Murray–Darling Basin Authority (MDBA) manages the Murray River system in close cooperation with state authorities to ensure reliable water supplies for all users.
MDBA and the state authorities provide crucial services, such as:
- storing, managing and delivering water
- operating salinity mitigation schemes
- enabling navigation
- supporting recreation and tourism.
Ensuring reliable supply
To ensure reliable supply, the river’s flow has been regulated for many years. Since the Hume Dam was completed in 1936, a continuous flow has been maintained throughout the length of the Murray.
Without regulation, the Murray would probably have stopped running during the current drought, and those of 1938–39, 1944–45, 1967–68, 1982–83 and 1997–98.
Operating structures
To regulate the river system, MDBA operates a number of structures, including:
- five major storages (Dartmouth and Hume reservoirs, Lake Victoria, Lake Mulwala, and Menindee Lakes (the Menindee Lakes are not an authority asset, but are leased from New South Wales))
- 13 weirs and locks
- five barrages (barriers constructed near the river mouth to stop the entry of sea water).
'Operating' the river
Each day, MDBA staff 'operate' the river system by directing releases from storages and controlling diversions of water from the river for irrigation and agricultural use, and for consumer in urban areas. They then advise staff of the state authorities working at the various structures of the rates of release for that day. During floods, flows may be adjusted every few hours.
Operational decisions take in a range of technical considerations such as flow requirements, salt and water level changes, estimated evaporation, forecast rainfall and the water-carrying capacity of the river at various locations.
Managing assets
To keep the dams, weirs and other structures in top operating condition, MDBA funds and supervises an investigation and construction program, with the work being carried out by state authorities.
Priorities for investigation and construction are based on risk assessments which include dam safety, occupational health and safety, public risk, and environmental risks, and security risks.
Intercepting salt
MDBA also manages a series of salt interception schemes to keep salt out of the river. The schemes typically involve large-scale groundwater pumping and drainage projects that intercept saline water flows and dispose of them by evaporation.
