Thursday, April 25, 2024

Tasmanian lake cleared of algal bloom

Tasmania’s Lake Trevallyn has been reopened to recreational water users, following recent water quality testing by the Tamar Estuary and Esk Rivers (TEER) Program.

The detection of a blue-green algal bloom during routine testing in January prompted the West Tamar and Meander Valley Councils to close the lake to recreational users, with the TEER Program increasing testing in both the lake and the Cataract Gorge First Basin.

At current levels and based on national guidance, the bloom no longer poses a risk to recreational users and the lake has been reopened, the Councils said in a joint statement today.

NRM North Operations Manager, Andrew Baldwin said the TEER Program would continue to monitor the bloom closely and conduct weekly testing at the Trevallyn boat ramp and at the Blackstone Park beach until at least the end of April.

“It can be difficult to predict how a bloom will behave but we have seen levels of blue-green algae reducing over the last few weeks,” Mr Baldwin said.

“We’ll keep testing and sharing weekly updates with the responsible agencies and the community, so everyone can make informed choices.”

The National Health and Medical Research Council has a traffic light system to inform the response to blue-green algae blooms which are:

  • Surveillance (Green) — low-levels, no public health risks, monitor as normal;
  • Alert (Amber) — increasing levels, no health risks to recreational users, increase monitoring;
  • Action (Red) — high levels, health risks to recreational users, maintain increased monitoring;

Mr Baldwin said algal concentrations at Lake Trevallyn are now considered to be at the ‘alert’ or ‘amber’ level, while the First Basin is at the ‘surveillance’ or ‘green’ level.

“The national guidelines recommend that at least two successive results at lower counts are recorded before the advice is downgraded,” he said.

“The TEER Program samples taken over the past fortnight have shown a decrease in the concentration of blue-green algae across all testing sites.”

The TEER program continues to work closely with members of the Lake Trevallyn Working Group, which includes Hydro Tasmania, TasWater, the Department of Health, West Tamar Council, Meander Valley Council, the City of Launceston, Tasmanian Irrigation and the Institute of Marine and Antarctic Studies.

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