Health unit warns of blue-green algae blooms in Midland

Little Lake Park in Midland, Ont. (CTV News)

The health unit is warning swimmers: if in doubt, stay out.

With the onset of the hot weather, the Simcoe Muskoka District Health Unit encourages local residents to exercise caution around slow-moving waterways.

• RELATED | Simcoe County, Muskoka brace for multi-day heat wave

The first blue-green algae bloom of 2023 was recently confirmed in Little Lake in Midland.

Blue-green algae occur naturally in freshwater and can multiply 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 water's surface 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.

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The health unit recommends taking precautions if you spot blue-green algae:

• Do not drink or use water for food preparation, including infant formula.
• Do not boil and drink water containing blue-green algae because toxins are not destroyed by boiling, which might increase toxins.
• Use an alternate source of safe drinking water, such as bottled water, for the duration of the bloom.
• If you see a bloom, stay out of the water, and keep your pets out. You cannot tell if a bloom is harmful by looking at it, so it's best to use caution and stay away.
• Do not swim, boat, or play water sports in areas with harmful algae or cyanobacteria.
• Do not use herbicides, copper sulphate or other algaecides that may break open algae cells and release toxins into the water.

Symptoms following contact or consuming toxins from a blue-green algae bloom can include skin irritation, 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, visit the health unit online.

Swimming has been cancelled at the following beaches as a routine matter and will be reopened after water tests confirm low levels of bacteria.

Gravenhurst

• Bass Lake Park Beach
• Franklin Park Beach

Innisfil

• 9th Line Park Beach
• Innisfil Beach Park North
• Leonard's Beach

Midland

• Little Lake Park Midland Beach
• Pete Pettersen Park Beach

Oro-Medonte

• Bayview Memorial Park

Ramara

• Atherley Ball Park Beach
• Brechin Beach
• Lagoon City Park Beach
• The Steps