Blue-green algae and GRCA reservoirs

Hot summer days are great for spending time outdoors, but also create the perfect conditions for algae to grow and bloom in large bodies of water.

The presence of a suspected small blue-green algae bloom has been observed near the west side of Shand Dam at Belwood Lake reservoir. Historically, blue-green algae blooms have occurred at the Grand River Conservation Authority’s (GRCA) Belwood Lake, Conestogo Lake, Guelph Lake and Woolwich reservoirs, as well as at Snyder’s Flats. There is permanent signage at these locations advising visitors of the potential for blue-green algae blooms and precautions that should be taken.

Belwood Lake Conservation Area visitors, recreational users and cottagers should implement the following safety measures when blue-green algae is visible:

• Keep children and pets away from the algae.
• Avoid contact with the algae.
• Don’t eat fish from the lake.
• Don’t use the water for drinking or any other purpose.
• Boating is allowed, where permitted, but boaters and recreational users should avoid touching the algae.
• Don’t swim in areas where you see scum, or it is accumulating along the shoreline.

The Ministry of the Environment, Conservation and Parks and the Wellington-Dufferin-Guelph Public Health Unit have been notified. Anyone with health-related questions may contact the Wellington-Dufferin-Guelph Health Unit.

Blue-green algae thrive on nutrients from fields and lawns that find their way into local waterways and reservoirs during heavy rainfall and spring melts and cause their populations to grow rapidly, forming blooms or scum on the surface of the water. Some varieties of blue-green algae can produce toxins that are harmful to both people and pets.

When an algal bloom starts to grow, a noticeable green or brown scum will form on the surface of water bodies and the water look like green or bluish-green pea soup. Once blue-green algae are in full bloom, it may look like spilled ‘paint’ along the shoreline. A new blue-green algal bloom often smells like fresh cut grass, while an older bloom can smell like rotting garbage.

More information about blue-green algae

• Visit the GRCA website at https://www.grandriver.ca/en/our-watershed/Algae.aspx to learn more about blue-green algae on GRCA reservoirs.
• Visit the Ministry of the Environment, Conservation and Parks website to learn more about blue-green algae.

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Media Contacts:

Lisa Stocco, GRCA Director of Strategic Communications and Environmental Education
Phone 519-621-2763 x2316  |  Email lstocco@grandriver.ca

Serena Catania, GRCA Supervisor of Communications and Marketing
Phone (519) 621-2763 x2240  |  Email scatania@grandriver.ca