Spillway work on the way for Warren Reservoir’s dam

SA Water will commence work this month to reduce the height of Warren Dam’s spillway, as part of proactive measures to ensure the dam continues to operate safely during major rainfall events.

Located near Williamstown, Warren is a 110-year-old dam primarily used to supply water to support viticulture irrigation across the Barossa Valley.

While the dam remains safe, geotechnical and structural investigations by SA Water have identified recent changes in its condition, which require action.

Under expert engineering advice, SA Water will implement two interim measures to improve the stability of the dam during major rainfall events – defined as events higher than a ‘one in one hundred year’ event – by reducing the spillway’s height and lowering the water level.

SA Water’s Senior Manager of Infrastructure Planning and Strategy Dr Daniel Hoefel said these changes are an interim step to ensure the dam continues to operate safely, while the utility explores long-term solutions.

“I want to assure neighbouring communities that Warren Dam continues to remain safe, and these interim measures demonstrate our proactive and robust approach to responsible dam management,” Daniel said.

“We’ve been undertaking a detailed engineering review of Warren Dam during the past six months as part of our long-term upgrade program, which found changes in the condition of the dam causing a reduction in stability at full capacity.

“Importantly, these changes are not unexpected given the dam’s more than a century old and was built to engineering standards from that time.

“While it doesn’t impact the dam under normal operating conditions, this change in stability could increase the risk of the dam being unable to safely manage major rainfall events if it was at full capacity.

“We’re taking action now through these two interim measures to ensure it continues operating safely during a major rainfall event while we explore long-term options to strengthen the dam.

“We’ve already implemented one of these interim measures by reducing and holding the water level at around 65 per cent to create space in the reservoir for water captured from rainfall.

“In addition, we’re also reducing the height of the dam’s concrete spillway to further improve its stability and capacity to manage major rainfall events.

“This will be achieved by lowering the concrete spillway crest by around 1.9 metres to enable the reservoir to continue to safely release water to South Para Reservoir once it reaches this lower operating level.

“Until the height of the spillway is reduced, we’ve set up a temporary pumping system on the reservoir to maintain the desired water level and enable work to be undertaken safely by diverting water downstream.

“While the work is being undertaken, we’ll continue to inspect Warren Dam every day as part of our regular operations. The safety of the community and our people is our priority.”

Warren Reservoir Reserve remains open for visitors to access for recreational activities such as kayaking and walking, with the reserve’s western section remaining temporarily closed during work on the spillway – which is expected to be completed in early September.

Mr Hoefel said the utility has been reviewing the 110-year-old Warren Dam since 2023 as part of a long-term initiative to upgrade the structure.

“These changes we’ve recently observed are entirely consistent with its age and the engineering standards at the time it was constructed,” Daniel said.

“With the focus of our long-term upgrade program already on Warren, we’ll use our recent learnings on the dam’s condition to inform our ongoing work which is exploring potential design and upgrade options.

“At this stage, we expect to share the outcomes of this project with the community later this year.”

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