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Water management facts

Drought and water allocations

  • Water allocations and entitlements vary from state to state and these differences mean that some entitlement holders have an allocation, while others have little to none.
  • In times of drought, allocations are reduced the same way for all water users—including the environmental water holders.
  • Through the Basin Plan, water is prioritised for critical human needs—for drinking and household water before being allocated for any other use.  In severe drought when rivers cease to flow, it’s not physically possible to supply water, and this has now occurred in some towns in the northern Basin.
  • The year 2018 was the hottest year on record for the Murray-Darling Basin. Extremely low rainfall such as during the past two years has only occurred on two other occasions since 1900.

Read the latest MDBA drought update

Unused water allocations

  • Sometimes water users don’t use the full amount of water allocated to them in a given year.  

  • The percentage of water that is allocated and not used varies year-to-year, and depends on climate conditions, rainfall, trade, infrastructure development and individual business decisions 

  • Sometimes allocations aren’t used because people choose to carry their water over to the following year, or the year after that, as a strategy to get through dry times

  • Irrigators can also opt to sell the allocated water that they do not use.  

  • If irrigators do not use, sell or carryover their allocation within three years, that volume of water is returned to the overall pool of water.  

  • Only a very small amount of water allocated is not used or sold.   

More about water allocations

River Operations: The Barmah Choke and water delivery

  • The Barmah Choke is a narrow section of the River Murray that runs through the Barmah–Millewa Forest.
  • The Choke restricts the flow of the River Murray to around 7,000 megalitres per day.
  • River managers consider the limitations of using the Choke when delivering water downstream.
  • The Choke has a trade restriction to protect delivery to existing entitlement holders and to maintain the river environment in the Choke.
  • When water goes through the forest most of it makes its way back into the river again downstream of the Choke.

More about the Barmah Choke

Water losses in the River Murray

  • Losses occur when water evaporates, is used by plants, or seeps into the ground. The Basin has an extremely high evaporation rate.
  • These losses are factored into water orders through ‘conveyance’—which is the water needed to deliver a water order.
  • Conveyance losses vary from year to year, depending on demand for water and conditions including rainfall, soil condition, heat, wind and inflows from tributaries.
  • Low inflows and hot conditions will lead to higher than average losses.

More about losses in the River Murray

Menindee Lakes

  • Menindee Lakes water storage is owned and operated by New South Wales

  • The Murray–Darling Basin Agreement sets out the rules for the shared resources of the River Murray system, including Menindee Lakes.

  • The MDBA can only use the water in the Menindee lakes when volumes are high (above 640 GL) until they fall below 480 GL.

  • The MDBA cannot drain Menindee Lakes. Once the water level is low (below the 480 GL trigger point), New South Wales manages the water to best meet local demands.

  • The lakes are in a semi-arid area and are shallow with a large surface area. In most years they lose the equivalent of one Sydney Harbour of water to evaporation.

  • When there is more water in the Menindee Lakes (total storage volume is 1,731 GL), they may lose up to up to 700 GL a year in evaporation.

More about managing Menindee Lakes

Flows to South Australia

  • New South Wales and Victoria need to share water with South Australia each year under the Murray─Darling Basin Agreement.
  • The most South Australia can receive as an entitlement is 1850 gigalitres each year, but flows to South Australia can be much higher during flood.
  • The South Australian government has to use some of its entitlement to run the river in the same way other states do.
  • On its way to South Australia, water provides important recreational and environmental benefits to communities along the river.

Why the river needs to connect to the sea

  • It is important that the river reaches the sea to flush sediments and salt out of the system.
  • There is currently not enough water flowing to the end of the river system to maintain the health of the Lower Lakes and Coorong.
  • By reducing seawater inflows, barrages near the Murray Mouth protect the Lower Lakes from becoming too saline.
  • High salinity reduces water quality and would permanently damage the lakes, the Coorong and the upstream river environment.

More about flows to the lower Murray–Darling Basin

Sharing River Murray Water

  • New South Wales, Victoria and South Australia have a long-standing agreement to share the water of the River Murray and the rivers that flow into it.  
  • The Murray–Darling Basin Agreement specifies how the water is shared. States decide how to allocate their share of water to entitlement or license holders such as farmers.  
  • The MDBA delivers water in the River Murray System on behalf of the states and has no involvement in setting entitlements or allocations.  
  • States own the water in the system and provide entitlements, or licences to water users. 
  • All water entitlements have the same conditions of use – the rules are the same for individuals, businesses and environmental water holders. 
  • The amount of water allocated by states depends on how much water is available and the type of entitlement held. 
  • Entitlements are permanent rights to water and allocations are the amount of water you get against that entitlement from year to year. 
  • Entitlements and allocations can be bought and sold on the water market. Entitlements to reliable water cost more to buy, entitlements or licenses with less reliable water are cheaper. 

More about sharing the water

Limits on water use

  • There’s a limit to the amount of water that can be taken from the rivers for towns, industries and farmers in the Murray–Darling Basin.  Each of the 29 river catchments and 80 groundwater areas has their own limit. 

  • For many years, state governments managed water use through their own cap on water diversions. A new system, known as the sustainable diversion limit, has replaced the cap system. It came into effect in 2019 and is binding on all states in the Basin

  • Water users are legally entitled to use all the water allocated to them by their state government. 

  • The amount of water available to allocate changes from year to year and depends on storage levels and weather conditions.

More about sustainable diversion limits

Water for the environment

  • Everyone benefits from a healthy river, farmers and communities also need a healthy and sustainable river. 
  • Environmental water holders are working together to help critical habitats and species survival during drought.   
  • They have some high-reliability water allocations in the southern Basin along with water carried over from last year.   
  • The value of water for the environment builds as it moves downstream and is reused through wetlands, floodplains and in the river.  
  • Without dedicated water, the natural environment would be severely stressed. In Spring 2019, the environmental water holders targeted:  
    • Flows in the Murray to support river red gum forests at Barmah-Millewa and Koondrook-Perriicoota  
    • Flows in the Goulburn River, which also boosted outcomes in the River Murray  
    • Gunbower Creek to help fish populations  
    • Hattah Lakes to help black box trees and local fish   
    • The Riverland wetlands and floodplains and the ecology of the Lower Lakes 

More about the outcomes of water delivered for the environment

Updated: 09 Dec 2019