Upper Murrumbidgee River high-flow environmental release

Property owners on the upper Murrumbidgee River and other stakeholders are being advised of a large water release being made from Tantangara Dam on 25 September this year, as part of ongoing efforts to maintain the river’s ecological health.

The single environmental high flow for the 2025/26 water year has been organised by the NSW Department of Climate Change, Energy, the Environment and Water (DCCEEW) in close consultation with the Snowy Advisory Committee and Snowy Hydro.

The release of 1,700ML/day will be made from Tantangara Dam into the upper Murrumbidgee River on 25 September 2025, starting at midday for 24 hours. The plan also includes smaller, frequent releases throughout the water year.

High-flow environmental water releases improve the health of the river by flushing fine sediment and improving connectivity, providing opportunities for fish and other native animals to move and wetting and filling riverside wetland areas.

There will be elevated flows on the days leading up to and following the release to create a more natural flow release pattern (hydrograph) that maximises ecological benefits.

The NSW Government is committed to keeping the public informed and will issue a reminder closer to the event. It is also important to note that the plan is subject to change, depending on weather, operational and environmental conditions.

As an outcome of the Snowy Water Licence Review, flexible delivery of smaller flows will also continue, enabling the volume and timing of releases under 1,400 ML per day to quickly change to respond to natural cues such as rainfall events.

Please check the DCCEEW website for any changes closer to each of the planned events at: Snowy Montane.

NSW Department of Climate Change, Energy, the Environment and Water Director Asset Management and Performance, Aurelio Lindaya:

“Up until now, environmental releases here have been capped at 1,500 ML/d due to infrastructure and operating constraints but this year we’re trialling a larger flow of 1,700 ML/d to move more sediment off cobbles which improves fish passage and habitat for the Macquarie perch spawning.

“Snowy Hydro is currently working to address these operating constraints to deliver this flow, and the NSW Government is undertaking a risk assessment to ensure we get the balance right.

“The results from previous studies show that Snowy montane rivers respond well to these seasonal high-flow events and this continuing approach has received input and support this year from the Snowy Advisory Committee and ecological experts.

“Downstream landholders and visitors to the area are encouraged to make appropriate plans ahead of the water releases, including securing watercraft and moving stock, pumps and infrastructure to higher ground and being aware of flows.”