How water is allocated
The Water Allocation Plan for the River Murray Prescribed Watercourse includes principles to guide the process for making water available for allocation to entitlement holders. Water available for allocation comes from South Australia’s River Murray Entitlement of up to 1,850 gigalitres (GL) per annum under the Murray-Darling Basin Agreement (the Agreement).
The River Murray Water Allocation Plan sets out a transparent approach to making water available for allocation and the hierarchy applied when allocations are made. This takes into account economic, social and environmental considerations.
How is the volume of water available to South Australia from the River Murray determined?
In most years, South Australia receives its full Entitlement of 1,850 GL, which is made up of:
- Dilution and Loss Entitlement – 696 GL
- Consumptive Entitlement – 1,154 GL
The actual volume of Entitlement that South Australia receives each year is determined by the Murray-Darling Basin Authority (MDBA) in accordance with the water sharing rules of the Murray-Darling Basin Agreement. These rules set out how water must be shared between South Australia, New South Wales and Victoria.
Once advised by the MDBA on Entitlement availability, the principles in the Water Allocation Plan for the River Murray Prescribed Watercourse guide the process for determining how much water can be made available for allocation.
What happens in dry years?
During dry periods, South Australia’s Entitlement may be less than 1,850 GL. In these years, there may not be enough water available to meet the needs of all water users, including the environment. A transparent process for allocation decision making assists all water users in planning and preparing for dry conditions. This process is explained in the water allocation fact sheet.
When South Australia does not receive its full Entitlement of 1,850GL, the opening allocation for any water access entitlement on 1 July may be less than 1 kL per share. When this happens, allocations are reviewed at least monthly until South Australia is advised by the MDBA that it will receive its full Entitlement. If water conditions and storage volumes improve, allocations to water access entitlement holders can be increased.
The Adelaide Desalination Plant
The plant was built on the back of the Millennium Drought to provide a climate-independent source of water, in addition to the state’s reservoirs and the River Murray. The combination of these sources provides the necessary water security to underpin the state’s economic and population growth to 2050.
The Adelaide Desalination Plant (ADP) was constructed as an insurance policy for urban water supplies to ensure that sufficient water is available to meet Adelaide’s needs in extremely dry years. The Adelaide Desalination Plant (ADP) also affects how River Murray water allocations are made.
The ADP makes a major difference to how SA Water's water is shared between all users of the SA River Murray in dry years – with 50 GL of available River Murray water released to holders of irrigation licenses in these years. This would not be possible without the insurance provided by the ADP. The additional 50GL for River Murray irrigators may be reduced by the Minister in the future to reflect growth in Adelaide’s demand.
The ADP is currently operating at minimum production, contributing on average 30 ML per day for nine months of the year, producing approximately 8 GL per year.
For more information on how the Adelaide Desalination Plant works, visit the SA Water website.
River Murray water allocation frameworks