Residents urged to stay away from Lake Gwelup and Jackadder Lake in Woodlands amid algal bloom

Residents and pet owners around Lake Gwelup and Jackadder Lake in Woodlands are being urged to stay away from the water at the popular parks, after potentially toxic algal blooms were confirmed at both locations.

Water sampling by the City of Stirling has confirmed the presence of blue-green algae species capable of producing toxins that can cause illness in people and animals.

Signs have now been erected around both lakes, warning visitors the water may harm humans and animals.

Mayor Mark Irwin said the blooms were first reported in late December, and last week laboratory tests identified the presence of microcystis aeruginosa, dolichospermum species and raphidiopsis raciborskii — all blue‑green algae known as cyanobacteria.

He encouraged locals to keep clear of the water, given the algae could cause skin irritation, nausea, vomiting and other health problems in humans and animals if they came into contact with the skin or were ingested.

“We’re urging the community to avoid all contact with the affected water and to keep their dogs on a leash to prevent accidental exposure,” Mr Irwin said.

“We will be undertaking follow‑up water sampling and ongoing monitoring at the lakes as advised by the WA Department of Health until the water quality is consistent with national guidelines.”

Algal blooms generally occur when temperatures are warm, the water is stagnant and nutrient levels are high, creating ideal conditions for rapid algae growth.

The city expects the blooms to clear up when the weather conditions shift.

“The duration of blue‑green algal blooms is influenced by environmental factors, such as temperature, nutrient levels, rainfall and water movement. As such, we are unable to provide a clear timeframe,” Mr Irwin said.

“Blooms often dissipate naturally as weather conditions change.”

Members of the public who notice signs of an algal bloom in local waterways are encouraged to report it to the Department of Water and Environment Regulation’s Algal Watch team.