Cyanobacterial cell count prompts St. Mary Lake notice


A cyanobacterial bloom in St. Mary Lake has prompted a notice from the Capital Regional District Water Quality Division to the Salt Spring Island Watershed Protection Alliance. 

According to a May 19 SSIWPA news release, “The lake water showed 5,935 cyanobacterial cells per millilitre, which is above the trigger point for potential cyanotoxin production. However, the indicator for cyanotoxicity was not detected at this time (microcystin).”

There is currently no risk for people drinking treated water from the Fernwood, Highland or North Salt Spring Waterworks District systems. However, people should not consume raw or private-licensed home-treated water from St. Mary Lake at this time. 

The cyanobacterial cell level is well below the limits for recreational use, but “precaution is suggested with swimming,” states SSIWPA. 

“A toxin test on this water source will be performed weekly during the bloom. If microcystin is detected in the raw water, a toxin test will be performed on the treated water.”

Additional samples will be submitted weekly until two consecutive samples have a cell count below 2,000 cells/mL and no microcystin is detected. 

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