Update: Blue-green algae and GRCA reservoirs

The presence of a suspected blue-green algae bloom has been observed at the beach at Belwood Lake Conservation Area. The Ministry of the Environment, Conservation and Parks (MECP) and the Wellington-Dufferin-Guelph (WDG) Public Health Unit have been notified.

The GRCA consulted with WDG Public Health who has recommended a beach closure due to the observation of suspected blue-green algae impacting the swimming area. The beach, part of a one-acre spring-fed quarry within the conservation area, is now closed. The closure is expected to be in effect until after the algae bloom has dispersed. Belwood Lake Conservation Area visitors and recreational users are reminded to obey posted signage, and should implement the following additional safety measures:

• Keep children and pets away from the algae.
• Avoid contact with the algae.
• Don’t eat fish from the water body.
• Don’t use the water for drinking or any other purpose.

Anyone with health-related questions may contact the Wellington-Dufferin-Guelph Health Unit.

More information

The previous notice of a small blue-green algae bloom observed in the Belwood Lake reservoir remains in effect. Belwood Lake Conservation Area visitors, recreational users and cottagers should continue to be aware of conditions and refer to the safety measures described in the July 24, 2025, communication.

The beach at Conestogo Lake Conservation Area remains closed. For more information on the Conestogo Lake beach closure, please refer to the August 22, 2025 news release.

Historically, blue-green algae blooms have occurred at the Grand River Conservation Authority’s 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.

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.

Visit the GRCA website to learn more about blue-green algae on GRCA reservoirs. The MECP website provides additional information about blue-green algae.

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