WATERNSW has reduced the amount of water released from the Menindee Lakes, PICTURED, from 1000 megalitres per day (ML/day) at weir 32, to 700ML/day.
The flow rate is expected to remain at 700ML/day until the total volume held in the lakes reaches 480 gigalitres.
Changing the flow rate in this way is expected to provide conditions favourable to Murray cod breeding during the coming weeks, according to Murray Darling Basin Authority (MDBA) head of river operations, Andrew Reynolds.
He said that lowering the rate at which water was released had been agreed by the MDBA, the Victorian, South Australian and NSW governments, and the Commonwealth Environmental Water Holder (CEWH).
“In accordance with the longstanding Murray-Darling Basin Agreement, the MDBA accesses water from Menindee Lakes for use in the River Murray system until the volume of water in the lakes falls below 480 gigalitres,” Mr Reynolds said.
“The slower rate of release will result in less water overall being available from Menindee Lakes to meet demands in the River Murray system.
“That’s because the longer water remains in the lakes, the longer it will be exposed to high rates of evaporation.
“The difference, however, will be made up by the Commonwealth Environmental Water Holder’s entitlements held in the Murray Valley.”
Mr Reynolds said that a key aspect of coming to this kind of arrangement was understanding and calculating how the flow change could be done without adversely impacting on the water resource as a whole.
“The agreed method means CEWH entitlements can influence a flow regime in the Lower Darling without affecting overall water security,” Mr Reynolds said.
WaterNSW executive manager System Operations, Adrian Langdon, said the agreed arrangement will mean that Menindee Lakes releases of around 700ML/day are likely to extend into early December.
“This is a one-off arrangement put in place by water managers to secure an environmental benefit without cost to other water uses,” he said. “Once below 480 gigalitres, water in the Menindee Lakes can no longer be called on by the MDBA, and will continue to be managed by WaterNSW to protect supplies for the future needs of Lower Darling and Broken Hill communities.
“WaterNSW’s recent operations have ensured that when the 480 gigalitre trigger is reached the majority of the water is in the upper two lakes which will be used as storage to meet future needs.”
WaterNSW and the MDBA will provide further details on flow rates in coming weeks.
Current dam storage information is available on the WaterNSW website.