RESOLVED: Blue-Green Algae Bloom at Prior Lake

Aug 03, 2021 (updated Oct 08, 2021, 10:11am)

As of Oct. 8, the advisory has been lifted at Prior Lake. However, blue-green algae blooms are unpredictable and may occur at any time.

The blue-green algae advisory is now lifted for Prior Lake, located in Thetis Lake Regional Park.

Water samples collected indicated a “below detection limit” result for cyanotoxins. The extended absence of blue-green scum combined with test results are good indicators that the bloom is over. 

Park users are reminded to watch for the distinctive blue-green sheen that can appear on the lake surface at any time. These blue-green algae are known toxin producers. Ingesting water containing the blue-green algae may cause a range of symptoms, including headaches and abdominal pain in humans, and can lead to lethal liver damage in dogs. 

Please visit  and Twitter @crd_bc for updates on active alerts. To learn more about blue-green algae visit our website

Thetis Lake Regional Park map (PDF)