The Menindee Lakes were modified during the 1950s and 1960s to provide Broken Hill with a reliable water supply and to supply water for irrigation to NSW, Victoria and South Australia. On average 426 gigalitres of water is lost in evaporation from the lakes system each year. A series of investigations has been undertaken by the NSW Government since 1995 to identify potential structural works and management changes to improve the efficiency of the Menindee Lakes and to reduce evaporation losses.
The Menindee Lakes system is located on the Darling River, about 200 kilometres upstream of the junction of the Darling and Murray Rivers. The lakes represent a significant natural, cultural and economic resource for Australia.
The large wetland ecosystem within the Menindee Lakes supports a diverse range of native flora and fauna - when full, there is more bird species found here than at Kakadu.
Prior to the construction of the Menindee Lakes Storage Scheme, the lakes naturally filled during high river flows and subsequently receded to form a series of pools. High evaporation rates at times dried the lakes out. Structures were built to enhance the ability of the Lakes to store and release water and include a number of weirs, regulators, levees and channels.
Menindee Lakes is made up of nine lakes, but generally water is stored in the four larger lakes - Lake Pamamaroo, Lake Wetherell, Lake Menindee, and Lake Cawndilla.
The lakes have a nominal full supply volume of 1,730 gigalitres and can be surcharged to hold up to 2,050 gigalitres during floods.
Water Savings measures
The competing demands of cultural heritage, environmental values and efficient water storage make the management of the Menindee lakes one of the most complex systems to manage in Australia.
The past 20 years has seen constant work involving negotiations and studies including the Darling River Water Savings project and agreements to progress options that will both save water, protect the environmental and cultural heritage values while ensuring supply for communities in both NSW Victoria and South Australia.
The Part A Report (PDF 2.5 MB) provides the outcomes of the preliminary phase of this project. The report outlines potential water saving schemes aimed at reducing the losses from the Menindee Lakes, securing water supply for Broken Hill and high security users, increasing water use efficiency, and delivering water for the environment. The water saving schemes include possible changes to the operation of the Menindee Lakes.
The Part B Final Report (PDF 5.3 MB) provides an overview of six options for operational and infrastructure changes to the Menindee Lakes storage and five options for Broken Hill's water supply.
In July 2010, NSW and the Commonwealth Government signed a Memorandum of Understanding (PDF 264 KB) agreeing to investigate the Commonwealth's preferred option for infrastructure and operational changes at the Menindee Lakes which could deliver water savings of up to 200 gigalitres per year.
However in June 2011, the NSW Government terminated the agreement because the Commonwealth proposal did not meet the conditions listed in the MoU. NSW Government found that:
- the Broken Hill community opposed the groundwater supply due to cost and water quality issues
- the reliability of supply to users downstream of Menindee Lakes would have been affected in dry years
- two of the Menindee Lakes would have had to be shut down resulting in significant environmental and social impacts.
For more information, read An overview of water saving investigations at the Menindee Lakes – the proposed changes under the Memorandum of Understanding between the Commonwealth and NSW to the lakes and water supply to Broken Hill (PDF 864 KB).
An independent review of the MoU was also undertaken. The Review of Hydrological Investigations Carried Out Under the Menindee Lakes Memorandum of Understanding (PDF 5 MB).
The way forward - water savings opportunities
There has been significant public debate about the need for achieving water savings to reduce the impacts of the on-going purchase of water licences to implement the Murray-Darling Basin Plan. NSW remains committed to investigating options for the improved management of the Menindee Lakes, but the final option chosen needs to recognise the enormous water supply benefits to NSW, Victoria and South Australia, and the natural environmental values of the Menindee Lakes. For more information read Menindee Lakes water savings opportunities - information paper (PDF 369 KB).
Releases to the Lower Lakes
In January 2010 the Premiers of NSW and South Australia agreed that water would be provided from Menindee Lakes to ensure flows would reach the Lower Lakes in South Australia.