SMDHU Public Notice: Blue-Green Algae Bloom in Mary Lake (Port Sydney beach area)

Posted On Monday October 25, 2021

The Simcoe Muskoka District Health Unit would like to inform residents and visitors to the Town of Huntsville that laboratory analysis has confirmed the presence of a blue-green algae bloom impacting the Port Sydney beach area on Mary Lake, Town of Huntsville.

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 when exposed in large amounts. Due to the confirmed presence of the bloom, we are asking resident and visitors to exercise caution that toxins may also be present. As a precautionary measure, the health unit urges residents and businesses to avoid drinking water from this lake 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 water sport activities where an algae bloom is visible.

The health unit strongly recommend seeking medical attention if symptoms such as skin, eye or throat irritation, allergic reactions or breathing difficulties occur while in contact with the bloom. Anyone who comes into contact with blue-green algae should wash with soap and water or rinse thoroughly with clean water. Swimming, bathing or showering with water not visibly affected by a blue-green algae bloom is not expected to cause health effects.

The health unit and the Ministry of Environment, Conservation and Parks will continue to work together to monitor the algal bloom and updates will be provided on our website

For further information, call Your Health Connection Monday to Friday 8:30 a.m. to 4:30 p.m. at 705-721-7520 or 1-877-721-7520. Links to general information and updates about blue-green algae are available on the health unit website at

This Public Notice was issued on October 22, 2021 by
Charles Gardner, MD, CCFP, MHSc, FRCPC
Medical Officer of Health