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Lake Glenmaggie releases for flood mitigation

29 March 2022 | News
29 March 2022

Controlled release from Lake Glenmaggie will take place from March through to May, with unseasonably high storage levels sitting above 90%. 

The reduction in water to the spillway sill, will enable maintenance to Lake Glenmaggie’s gates, while providing environmental benefits and flood mitigation. 

Southern Rural Water, Water Supply Manager, Simon Wilkinson said this was a great outcome for communities and the environment. 

“Without intervention, the storage level at Lake Glenmaggie will be unprecedently high, limiting the ability to mitigate floods downstream during the winter period,” Simon said. 

“This is still well above the average storage level for this time of year and with the predicted weather forecast, there is a high degree of confidence that the reservoir will fill in time for the new irrigation season. 

 “Our current storage level is approximately twice the average end of season volume and provides a high degree of confidence that the reservoir will fill in spring. 

The goal is to ensure the storage is full when customers need it, while protecting the integrity of the dam and minimising the risk to communities downstream, from flooding. 

The controlled releases from the reservoir during the coming weeks will ensure we can still meet the irrigation demands for the rest of the season. 

SRW will gradually lower the storage to just below the spillway sill (119,000 ML). This storage level is still approximately twice the average end of season volume and provides a very high degree of confidence that the reservoir will fill in spring. 

Southern Rural Water will work closely with the West Gippsland Catchment Management Authority to ensure that the rivers and waterways downstream from Lake Glenmaggie will receive maximum benefit from the water release to enhance the river health. 

“Whilst the catchment has received good recent rainfall and flows the release of water from Glenmaggie will support water-dependent vegetation, habitat for frogs, waterbugs and native fish,” Simon said. 

“The rivers and waterways downstream from Lake Glenmaggie will also receive required and timed freshers to stimulate fish movement.” 

Lake Glenmaggie is a highly reliable storage with a catchment four times the size of the Thomson Dam, despite being only one-fifth its size. Irrigation demand had been slower this season, largely due to consistent rainfall throughout the season and a wet catchment.