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 Menindee lakes one of the most complex systems to manage in Australia.
Ongoing work has been undertaken since the end of the 20th century involving multiple negotiations and studies. This includes the Darling River Water Savings project and agreements to progress options that will save water and protect environmental and cultural heritage values while ensuring supply for communities in NSW, Victoria and South Australia.
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 has remained 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.
In December 2013, the Australian and NSW Governments announced funding for project planning and detailed design work.
The investigations announced in December 2013, aim to implement a suite of measures designed to improve the management of Menindee Lakes. The package includes infrastructure works, operating rule changes and drought security water supply infrastructure for Broken Hill, which, if agreed, would realise annual water savings of up to 80 gigalitres and improve the storage efficiency of the lakes. The operation rules for the Menindee Lakes will require agreement of New South Wales, Victoria and South Australia and the project will be subject to consultation with the local conmmunities.