Menindee lakes releases continue to manage storage

Menindee lakes releases continue to manage storage

28 October 2021

WaterNSW will continue releases from Menindee lakes in coming months, an operational requirement that will also sustain the downstream environment and restore the lakes’ flood mitigation capacity if needed.

The lakes’ total storage level remains in flood surcharge, at approximately 1940 gigalitres (GL) – or 112% of capacity – and inflows are expected to persist into mid-December even without additional rain in the northern basin.

The releases are consistent with the rules under which WaterNSW must operate the lakes and will maintain flows in both the Lower Darling River and the Great Darling Anabranch, with the latter receiving its first significant flow since 2017.

Under the operating rules Menindee lakes’ storage must be reduced back to full supply level by 31 December 2021, which on present forecasts will require continuous releases throughout November and December of more than 200GL in total.

The flows into the lakes this year are the largest in a decade and have filled the lakes network for the first time since 2011-12. Even without further rain the estimated additional volume expected over the next nine weeks is 100-160GL.

The Bureau of Meteorology has announced an increased likelihood of a La Nina weather phenomenon for Spring and Summer, raising the prospect of rainfall across the northern basin generating further inflows in the months ahead.

Daily releases from the lakes are currently occurring at a rate of ~3.5GL/day, comprising 2.5GL/day from weir 32 into the Lower Darling and 1GL/day into the Anabranch.

Executive manager, Adrian Langdon, said WaterNSW is working with the respective NSW Government authorities and the Murray-Darling Basin Authority to maximise the benefit of the water.

“At present the lakes are above full supply level and into the flood surcharge zone. By reducing the current storage level we will meet our obligations under the operating rules, and also create capacity to capture the next inflows,” he said.

“In doing so we will extend the environmental benefit to the downstream river ecosystems, including the Anabranch, a move strongly supported by feedback from the local community when it was announced in September.”

More information

WaterNSW - storages

WaterInsights - river heights and flow data.

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