Murrumbidgee dams rising, Burrinjuck releases increased

Murrumbidgee dams rising, Burrinjuck releases increased

04 November 2020

WaterNSW has increased releases from Burrinjuck Dam as the storage rises to 92% of storage capacity as a result of the weekend rain event and agricultural demand increases.

Inflows to Burrinjuck peaked at a rate of more than 35,000 megalitres per day (ML/day), while large tributary inflows downstream of the dam generated high flows in the Murrumbidgee River at Wagga and resulted in supplementary access.

Blowering Dam, on the Tumut River, which also flows into the Murrumbidgee River, is sitting at 85% of capacity, with releases only continuing at the minimum allowable rate.

With Burrinjuck expected to reach 95% of capacity in coming days, and a second rain event forecast for this week, WaterNSW has increased releases to 4,000ML/day and is working closely with the Bureau of Meteorology to monitor weather forecasts.

WaterNSW river operators are making daily assessments of the situation and are expected to decide on whether to increase releases from Burrinjuck within days.

However with the best water availability for regional producers in years and corresponding expectations of high demand, retaining storage volume for agriculture, the environment and Murrumbidgee valley communities is top priority.

The Burrinjuck catchment in particular is saturated from recent rain events, while major tributary flows downstream of dams have added to river Murrumbidgee flow rates, notably from the Jugiong Creek, and Goobarragandra River.

WaterNSW executive manager of system operations, Adrian Langdon said the wet catchments, rising storage levels and weather forecast have prompted WaterNSW river operations personnel to prepare for the possibility of a spill.

“While there is no cause for alarm, the ongoing rain events – especially over the Burrinjuck catchment – are generating large inflows and we are monitoring the situation carefully,” he said.

“We work very closely with the BoM so we have access to the nation’s best weather forecasting, and we will use that information to help us decide whether to make flood mitigation pre-releases in the event of a significant rain forecast.

“As dam managers we are mindful that we cannot make releases to create airspace capacity to absorb inflows without a high degree of certainty that the anticipated inflows will replace those releases, and therefore not impact adversely on long term water security.

“The other consideration is that we don’t want to exacerbate a flood-prone river system downstream of the dam by adding water to the existing, naturally-occurring tributary flows.

“Conventional wisdom has it that all the water in the river originates from the dam – especially during a flood event – but this overlooks the major contribution of downstream tributaries that we have witnessed this week.”

Media contact – Tony Webber 0428 613 478.

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