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.

Kangaroo Creek’s new 50-metre-wide spillway has been called into action since the dam’s $94 million safety upgrade. The structure now safely carries excess water to the River Torrens below the reservoir. This follows its recently reaching of 100 per cent capacity.

The reservoir’s storage has more than quadrupled since the start of winter. It received around 15 billion litres of water during that time. This inflow prompted the spillway to gradually release water to self-manage the storage level.

Completed in December 2019, a significant 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 that the full reservoir is in stark contrast to when it was temporarily emptied in 2018 to enable the dam safety upgrade.

“Not long ago, Kangaroo Creek was at zero per cent of capacity when it exposed the historic Batchelor’s Bridge. 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. It’s experienced a remarkable uplift in its storage level following persistent rainfall during August and September. With full storage, the spillway is doing precisely what it was designed and built for.

“The dam’s new design for the spillway saw it widened by 33 metres. It provides for a greater ability to pass extreme weather events safely. The dam’s safety was also elevated to keep it following our national guidelines.”

Kangaroo Creek spillway provides opportunities for safe releases of water

“There are also two ‘portals’ 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. They are also storing water temporarily to help minimise any impact on the river downstream,” said James.

“A small amount of excess water from the reservoir flows slowly down the spillway and into the River Torrens. The flow can increase due to rainfall later in the week and subsequent inflows.

“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. This benefits the environment as water releases help support the aquatic ecosystems and native fauna, which call downstream river systems home.

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.

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