Torrens Lake’s annual blue-green algae management program is now underway, in a bid to prevent algal blooms – and subsequent closures of this prominent Adelaide feature – over summer.

As part of the program, excavation of a channel at the Torrens Outlet at Henley Beach South will begin tomorrow to allow flows from upstream storages to reach the sea if required.

Green Adelaide Urban Water Team Leader Tammy Partridge said the program involves regularly monitoring algae levels at a series of locations throughout the lake.

“This year’s forecast drier, El Niño conditions make the lake more prone to an algal bloom, which is why management is beginning earlier than in previous years,” she said.

“During summer, water stops flowing into the lake and what’s in there starts heating up, making it susceptible to blue-green algae blooms – hotter weather and less water makes this more of a risk.

“This year we’re getting in early with proactive management in response to predicted weather conditions, to prevent the lake being closed.

“At high concentrations, toxins from some blue-green algae species can be harmful to people and wildlife, so without any management the lake would undoubtedly have to be closed to recreational use.”

Torrens Lake has suffered from blue-green algae blooms since the late 1990s. Since 2013, proactive management in the form of monitoring and freshwater flows has successfully prevented the closure of the lake.

Mrs Partridge said the amount of water released into Torrens Lake depends on summer weather conditions and the frequency and volume of rainfall.

“Monitoring takes place twice a week at 7 locations and freshwater is released if that reveals the threshold of blue-green algae has been reached,” she said.

“If required, further channel excavation at the Torrens Outlet at Henley Beach will also be undertaken and any sand removed during excavation will remain on the beach in the area.”

“If there are hooded plovers nesting on the beach at the time of excavation, BirdLife Australia volunteers will be onsite to make sure the birds are kept safe.

“Managing blue-green algae in the lake over summer is particularly important as this time coincides with Adelaide’s festival and events season, with many centred around the riverbank precinct, so it’s important that the lake is healthy and looks great too.”

This project is a collaboration between Green Adelaide, Department for Environment and Water, SA Water, Environment Protection Authority, City of Adelaide and the City of Charles Sturt.