Cyanobacterial bloom prompts health advisory at Lake Sundance
Posted Aug 14, 2026 11:17 am.
Last Updated Aug 14, 2026 11:18 am.
Health officials are warning residents after a cyanobacterial bloom has been detected in Lake Sundance in southeast Calgary.
Cyanobacteria, often appearing as blue‑green or brown scum or streaks on the surface, can produce toxins that cause rashes, sore eyes, nausea, vomiting and diarrhea.
Officials say people should not swim or wade where blooms are visible, avoid touching algae on the water or shore, and never drink or cook with untreated lake water. Whole fish and fish trimmings should not be eaten or fed to pets, though fillets contain fewer toxins.
Pets are especially vulnerable and exposure can be fatal.
Areas of the lake without visible blooms remain open for recreation.
The advisory will remain in place until further notice as wind and weather can shift the bloom around the lake. Anyone with health concerns or wishing to report a bloom can call Health Link at 811.
