Visitors to Prior Lake are advised to avoid the water due to a blue-green algae bloom.
The lake is located in Thetis Lake Regional Park and is managed by the Capital Regional District.
Blue-green algae can produce cyanotoxins. Ingesting water may cause a range of symptoms in humans, including headaches and abdominal pain. The toxin can lead to lethal liver damage in dogs.
The CRD says people should avoid swimming in the lake and should discourage pets from drinking or swimming in the lake.
The algae usually produce a visible blue-green sheen, hence its common name. But not all blooms are easy to see. The toxins can still be present even if you cannot see a bloom, which typically appears as surface scum on the water.
At this time, blue-green algae have not been detected at Upper or Lower Thetis Lake.
For updates on the status of the bloom, go to crd.bc.ca/alerts or Twitter @crd_bc.