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

River Torrens in the Adelaide CBD

Green Adelaide’s Dr Nadine Kilsby said 2020-21 would be the tenth 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 seven 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 Kilsby 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 Kilsby said that this summers’ recent occasional, but heavy rains, have produced flows into the lake that have helped keep levels of algae relatively low.

“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 keep algae in the lake at an acceptable level.”

As part of the annual program, a small channel was 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.

The project is supported by Green Adelaide, the Department for Environment and Water, SA Water, the Environment Protection Authority and the City of Adelaide.

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