The Grand River Conservation Authority says a small suspected blue-green algae bloom has been observed near the dam and islands at Shade’s Mills Conservation Area in Cambridge. An earlier notice for a small bloom at the boat launch at Belwood Lake Conservation Area remains in place.
Visitors are told to keep children and pets away from visible algae, avoid all contact with it, not eat fish from affected waters, avoid using the water, and not swim where scum has gathered. Boating and paddling are still permitted where they are normally allowed, but the authority asks paddlers not to touch the algae.
The GRCA has notified the Ministry of the Environment, Conservation and Parks and Region of Waterloo Public Health. Health questions go to the health unit, and anyone with symptoms is told to contact their physician.
Blue-green algae feeds on nutrients washed off fields and lawns into waterways and reservoirs during heavy rain and spring melt. A bloom can look like green or brown scum resembling pea soup or spilled paint, and can smell of anything from fresh-cut grass to rotting garbage. Some varieties produce toxins harmful to people and pets.
Conestogo Lake, Guelph Lake, the Woolwich reservoir and Snyder’s Flats have all carried blooms in past years.
Source: https://www.grandriver.ca/news/posts/update-blue-green-algae-and-grca-reservoirs-5/, 4 September 2026.
