An annual program - which successfully controls blue-green algae in Adelaide’s Torrens Lake during summer - is now underway.

Torrens Lake near Adelaide Festival Centre

Dr Nadine Kelly from Green Adelaide said 2021-22 would be the eleventh year of the River Torrens Water Quality Improvement Project, which has been successful in preventing Torrens Lake algae outbreaks and lake closures for the past eight years.

“During summer the Torrens Lake generally stops flowing and the lake slowly heats up. This creates the ideal conditions for blue-green algae to grow,” Dr Kelly said.

“At high concentrations, toxins from some blue-green algae species can be harmful to people and wildlife. When that happens, the lake has to be closed for recreational use.

“Since 2013, we have been monitoring algal levels and using flows of fresh water to successfully control blue-green algae in the lake.”

Dr Kelly said that the need for fresh water to control algae in the lake will depend on rainfall and the persistence of high temperatures over summer.

“If our continued summer monitoring reveals that the threshold levels of blue-green algae are being reached, flows of fresh water from upstream storage will be used to freshen lake water quality and maintain algae at an acceptable level.”

As part of the annual program, a small channel will be excavated across the narrow stretch of beach from the Torrens outlet to the sea at Henley Beach South, ensuring an easy passage for any water coming down the river. Channel excavation will take place this month. The channelled sand will remain on the beach in the area.

The project is a collaboration between Green Adelaide, Department for Environment and Water, SA Water, Environment Protection Authority and City of Adelaide.

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