MUSKOKA LAKES The health unit is urging caution to residents and visitors on the north side of Bass Lake, in Township of Muskoka Lakes, after a confirmed blue-green algae bloom was discovered.

The Simcoe Muskoka District Health Unit said today, Nov. 19, people should exercise caution where blue-green algae is visible and to take the following precautions:

  • Do not use the lake water for the preparation of infant formula
  • Do not allow pets or livestock to drink or swim in the water where an algae bloom is visible
  • Be cautious about eating fish caught in water where blue-green algae blooms occur
  • Do not use herbicides, copper sulphate or other algaecides that may break open algae cells and release toxins into the water
  • Avoid swimming and other water sport activities where an algae bloom is visible

They say blooms may make the water look bluish-green, or like green pea soup or turquoise paint.

Many species of blue-green algae (also called cyanobacteria) have the potential to produce toxins that are harmful to the health of humans and animals. The Ministry of Environment, Conservation and Parks will be further analyzing samples to determine the presence of any toxins.

Symptoms from consuming toxins from a blue-green algae bloom can include headaches, fever, diarrhea, abdominal pain, nausea and vomiting, and can be more serious if water is swallowed in large quantities.

The health unit says it working with the Ministry of Environment, Conservation and Parks to monitor the algal bloom.

Updates are available on their website

And to learn more about blue-green algae visit the health unit website at, or call Health Connection weekdays from 8:30 a.m. to 4:30 p.m. at 705-721-7520 or 1-877-721-7520.

The north side of Bass Lake in Muskoka Lakes Township is seeing signs of an algae bloom and the health unit urges residents and visitors and pets not to drink from it. (File photo)