Back to Search

SIMCOE MUSKOKA – A blue-green algae bloom has been confirmed on the southeast shoreline of Kempenfelt Bay (Bear Point area) and the southwest shoreline of Lake Simcoe (Innisfil Beach Park area), Town of Innisfil. The Simcoe Muskoka District Health Unit is encouraging residents and visitors to exercise caution.

Blue-green algae, or cyanobacteria, occur naturally in freshwater. Blue-green algae can grow rapidly to form dense blooms when the weather is warm, and the water is shallow, nutrient-rich, slow moving, and warm. Blooms are usually smelly and can make the water appear green, blue, turquoise, or olive green. They often form scum, foam, or mats on the surface of the water and may appear as though turquoise paint was spilled in the water.

Many species of blue-green algae have the potential to produce toxins that are harmful to the health of humans and animals. If you suspect a blue-green algae bloom, be cautious and assume that toxins are present to avoid exposure. If you spot a bloom, you can report it to the Ministry of the Environment, Conservation and Parks online or by phone at 1-866-MOE-TIPS (663-8477).

The Simcoe Muskoka District Health Unit recommends taking the following precautions when you spot blue-green algae:

  • If you see a bloom, stay out of the water, and keep your pets out of the water. You cannot tell if a bloom is harmful by looking at it, so it's best to use caution and stay away.
  • Do not drink the lake water or use it for cooking, including preparing infant formula and ice making, unless it has been treated by a municipal drinking water system. Municipal systems are tested regularly for safety.
  • Do not boil and drink water that may contain blue-green algae because toxins are not destroyed by boiling and boiling may increase toxins.
  • Do not use herbicides, copper sulphate or other algaecides that may break open algae cells and release toxins into the water.
  • Do not fill pools or spas with water directly from the lake.

Symptoms following contact or consuming toxins from a blue-green algae bloom can include irritation of the skin, eyes, nose, throat, or lungs, stomach pain, headaches, diarrhea, vomiting and in severe cases, liver damage. Symptoms can be more serious if water is swallowed in large quantities.

For a list of affected waterways and to learn more about blue-green algae, and the precautions to take before swimming or consuming water where there has been an algae bloom, visit smdhu.org/algae.

This notice was first issued by the Simcoe Muskoka District Health Unit on July 11, 2024.