All you need to know about the famous Menindee Lakes
- By: "Farm Tender" News
- Dairy News
- May 23, 2018
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Menindee Lakes is a chain of seven natural shallow lakes (four of them large) connected to the Darling River. They are near the town of Menindee and 110 km south-east of Broken Hill, New South Wales (NSW).
Historically, due to the flat terrain and hot, dry climate, the lakes would often naturally dry up. The NSW Government modified the lakes (completed 1968) to improve their storage capacity for farming, recreation, mining and urban water supply and to help manage floods in the Darling River.
About the lakes
Water from the lakes is used by Broken Hill, Lower Darling entitlement holders and, depending on the volume in the lakes, by the Murray–Darling Basin Authority (MDBA) to support demands on the River Murray.
The lakes are expansive but relatively shallow and located in a semi-arid climate. This means there can be large evaporative losses.
Operating the lakes efficiently is important. If the lakes were operated inefficiently, there would be less water for everyone.
How does the MDBA manage the River Murray System when water is available from Menindee lakes?
One of the core objectives of river operations is to operate the River Murray system efficiently and maximise water available to the Southern Basin states (Victoria, NSW and South Australia).
Minimising undesirable losses, such as evaporation, assists in maximising the water to the Southern Basin states and therefore all entitlement holders along the Murray.
The Menindee Lakes are relatively shallow storages, possess large surface areas and are located in a semi-arid climate, resulting in large evaporative losses. Water lost through evaporation is water that could have been allocated to the states and their entitlement holders. The MDBA actively operates the River Murray system to minimise evaporation. That is why water stored in Menindee Lakes is generally used in preference to the more efficient upstream storages of Hume and Dartmouth, with Lake Victoria used to re-regulate flows and supply South Australia.
Water is stored preferentially in Hume and Dartmouth Dams, where evaporation rates are much lower. Storing water in the storages furthest upstream also provides the greatest flexibility in meeting downstream orders — Menindee Lakes cannot meet orders upstream of Wentworth.
While water conservation and operational efficiency are the main objectives the MDBA also gives consideration to:
• NSW supply obligations (Broken Hill and Lower Darling entitlements
• structural integrity of the lakes
• water quality issues and
• environmental and cultural heritage features of the lakes.
When can the MDBA access water from Menindee Lakes?
Operation of the lakes is subject to the longstanding Murray–Darling Basin Agreement between NSW, Victoria, South Australia and the Australian Government. The agreement allows the MDBA to access water in the lakes to support downstream demand in the River Murray but only when the lakes’ volume rises above 640 gigalitres (GL) and until it drops below 480 GL.
Under the agreement, Menindee Lakes continues to be available to supply water for local requirements along the Lower Darling, including the Great Darling Anabranch.
Can changes be made to how the lakes are operated?
The NSW Government can change the way Menindee Lakes are used to meet Broken Hill and Lower Darling water needs. However, any changes to the 640/480 GL ‘triggers’ would need to be agreed between NSW and the other three governments that are party to the Murray–Darling Basin Agreement.
Do Menindee releases affect water allocations on the Murray?
While releases from Menindee Lakes do not directly meet demands upstream of Wentworth, they can reduce the amount of water released from the Upper Murray Storages. If Menindee Lakes were operated inefficiently, there would be less water available to the states and less water available for entitlement holders along the River Murray.
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