A third release of fresh water into the River Torrens started this afternoon (Friday 9 February) as part of an annual program to control algal levels in the river and Torrens Lake during summer.
Katharine Ward from Natural Resources Adelaide and Mt Lofty Ranges said flows of water in mid-December and early January, boosted by natural inflow from rain, had successfully helped control blue-green algal levels in Torrens Lake.
She said the project team undertakes regular water quality monitoring in the Torrens and the latest results indicated a flow of fresh water would be advantageous at this time.
Hydrogen peroxide has been trialled as a control agent for algae on a small scale in the river since 2016 however, a further trial has had to be postponed.
“While our monitoring indicates today’s release is ideally timed to lower the concentration of blue-green algae in both Torrens Lake and the river, conditions are not quite right for us to get valid results from another test of hydrogen peroxide,” Ms Ward said.
“We’re hoping that conditions might be more favourable for another trial of hydrogen peroxide sometime in the next four to six weeks.”
The River Torrens Water Quality Improvement program began in 2011 to trial different strategies to control blue-green algal growth in Torrens Lake during summer and early autumn.
Since 2013, the project has been successful in preventing lake closures through the use of high intensity flows of fresh water along the river.
Following the release of the water, local residents and visitors to the River Torrens Linear Park may notice higher than usual flows in the river for up to four days as water makes its way from the hills, through the city to the Torrens outlet at Henley Beach South.
Water resulting from the flows will be of a better quality than stormwater. However, as with all flows into the sea from urban areas, beach goers are encouraged to avoid swimming in turbid or discoloured water.
The River Torrens Water Quality Improvement program was developed with the support of the Adelaide and Mount Lofty Ranges Natural Resources Management Board, the Department of Environment, Water and Natural Resources, SA Water, Environment Protection Authority, and City of Adelaide.