New reservoir spillway christened by spring rain

Kangaroo Creek’s new 50-metre-wide spillway has been called into action for the first time since the dam’s $94 million safety upgrade, with the structure now safely carrying excess water to the River Torrens below the reservoir, after it reached 100 per cent capacity.

The reservoir’s storage has more than quadrupled since the start of winter – receiving around 15 billion litres of water during that time – prompting the spillway to gradually release water to self-manage the storage level.

Completed in December 2019, a major upgrade of Kangaroo Creek’s dam included significantly widening the spillway and raising the embankment to increase the dam’s flood capacity, while strengthening the dam wall to improve its ability to withstand earthquakes.

SA Water’s Senior Manager of Wastewater Expertise and Environment James Crocker said seeing the reservoir currently full is stark contrast to when it was temporarily emptied in 2018 to enable the dam safety upgrade.

“It doesn’t feel like too long ago, that Kangaroo Creek was at basically zero per cent of capacity – exposing the usually hidden historic Batchelor’s Bridge – and now only a few years on, the dam’s new spillway is making its debut,” James said.

“The reservoir was only sitting at around 21 per cent at the start of winter and it’s experienced a remarkable uplift in its storage level following persistent rainfall during August and September. With the storage full, the spillway is now doing exactly what it was designed and built for.

“The dam’s new design for the spillway – which was widened by 33 metres – provides it with a greater ability to safely pass extreme weather events, while elevating the dam’s safety to keep it in step with our contemporary national guidelines.

“There are also two ‘portals’, that are like short tunnels, located at the top of the new spillway. Although these are large enough to drive a car through, they effectively slow down the release of water by restricting outflow and storing water temporarily to help minimise any impact on the river downstream.

“A small amount of excess water from the reservoir is currently flowing slowly down the spillway and into the River Torrens, with the flow potentially increasing subject to rainfall later in the week and subsequent inflows.

“As much as possible, we’ve been proactively diverting water from Kangaroo Creek to be treated at our nearby Hope Valley Water Treatment Plant and supplied to our customers.

“This year’s healthy rainfall has meant a number of our other reservoirs, like Mount Bold and Myponga, are also relatively full, which is benefitting the environment as water releases help support the aquatic ecosystems and native fauna which call downstream river systems home.

“More natural inflows from the Mount Lofty Ranges catchment also means we’ve reduced the amount of carbon emissions that are associated with energy-intensive pumping of water from the River Murray.”

You can see Kangaroo Creek’s dam from the nearby lookout on Gorge Road. For everyone’s safety, SA Water asks people to be mindful when driving past this area or crossing the road to the lookout, as well as making sure to remain outside the perimeter of the dam site.

SA Water’s metropolitan reservoirs are currently sitting at a total capacity of 88 per cent, storing a combined 175 billion litres of water.

Contact:

Phone:

Email: