Blue-green algae: What to watch for this summer

Municipal drinking water systems are consistently monitored for blue-green algae and microcystin, a specific cyanotoxin known to have health implications.

Both raw and treated water undergo regular testing, alongside visual inspections of the lake and intake lines. Most municipal systems across Canada have never surpassed the maximum acceptable concentration of microcystin in treated water.

This indicates that the intricate treatment systems employed by the majority of municipal drinking water systems effectively eliminate blue-green algae and their associated toxins.

Residents will be promptly informed if microcystin levels in treated water exceed the Ontario Drinking Water Quality Standard. The likelihood of exposure to cyanotoxins from municipal drinking water is very low.

During the peak season, typically from June to October, homeowners and cottage owners should keep a close eye on lakes and rivers for signs of blue-green algae blooms.

Home treatment systems might not eliminate toxins from the water, and the water may not always have an unpleasant taste or odour.

Therefore, it is important to exercise caution and follow these guidelines:

• avoid drinking the water or using it for food preparation, including infant formula
• use an alternative source of safe drinking water, such as bottled water, throughout the duration of the bloom
• do not boil and consume water that may contain blue-green algae, as boiling does not eliminate toxins and may actually increase their concentration
• refrain from using herbicides, copper sulfate, or other algaecides that could rupture algae cells and release toxins into the water
• bathing or showering with water that does not visibly show signs of a blue-green algae bloom is generally not expected to pose health risks