A shot of the ACT's iconic lake, captured by Canberra photographer Vishal Pandey, shows the blue-green algae with hot air balloons flying over during the Canberra Day long weekend.

The National Capital Authority last issued an update to blue-green algae levels on March 4. Several areas including Black Mountain Beach, Yarralumla Beach, Acton Beach and Acton West Jetty were closed to swimming but "secondary contact recreation" such as sailing and rowing was allowed.

"Persons engaged in secondary contact recreation should be careful to limit any water exposure and should shower after contact with the water," the update via the swim guide website read.

"There is an increased risk of adverse health events from water exposure. Symptoms of exposure may include skin/mucosa irritation, flu-like symptoms, and gastrointestinal illness."

"Water users should look for algae warnings signs indicating the current alert level at major water entry points."

Swimming is currently allowed at Molonglo Reach.

The lake is regularly plagued with the algae, with an extreme alert issued in January which had the lake closed to swimmers and the Captain Cook Jet temporarily turned off.

Swimming in Lake Tuggeranong was banned in December due to blue-green algae levels.

Ngadyung beach at Lake Tuggeranong failed the water quality test on March 4. Advice is that swimming should be avoided for several days after heavy rainfall as bacterial levels are strongly affected by such events.

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