Date: June 25, 2019

A few showers ending after midnight then mainly cloudy. Risk of a thunderstorm late this evening and after midnight. Wind becoming southwest 20 km/h after midnight. Low 17.


Environment Canada
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Safe Water

Drinking Water

Recreational Water



This page was reviewed or revised on Wednesday, May 24, 2017 9:39 AM

Blue-Green Algae

Blue-green algae, more commonly known as pond scum, are bacteria that live in fresh water. Blue-green algae are usually found in shallow, warm, slow moving water, but may also live below the surface in deeper, cooler water.

During warm weather, blue-green algae can grow quickly to form a large mass called a bloom. In Ontario, blooms occur often during the late summer and early fall.

Blue-green algae grow best when there are high levels of nutrients in the water, such as phosphorus and nitrogen.

Many types of blue-green algae do not cause harm. However, when some types of blue-green algae form blooms, they can produce toxins that can be harmful to your health and the health of your pets. People can become ill from contact with blue-green algae toxins.


For more information on Blue Green Algae, visit the link below:
Ministry of the Environment and Climate Change

Nuisance Algae

Photo of nuisance algae washing up on the beach

Cladophera or "green algae" is a naturally occurring algae that grows on lake bottoms and happens when sunlight penetrates to the lake floor. This is caused by zebra mussels cleaning up the water and making it clear for sunlight to penetrate. As with most plants, the addition of nutrients such as phosphorous and nitrogen can accelerate the growth rate of algae.

As heavy algae growth dies off, the gases produced push the algae to the water surface. Heavy rainfall and wave activity cause it to wash onto the lake shorelines and settle on the beaches. When this happens, it appears like a "black muck" substance and can harbour bacterial growth.

Bathers, especially children, should not play in this area. If the water appears clear, then it is safe to swim.


For more information on this type of algae, visit one of the links below:
Healthy Lake Huron
The Lake Huron Centre for Coastal Conservation