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  • Writer's pictureFriends of Deer Lake

Harmful Algae Bloom in Deer Lake

Updated: Nov 25, 2018

Reprinted from North Bay Parry Sound District Health

Location of Algae Bloom

The Health Unit would like to advise the public that a harmful algae bloom (cyanobacteria), also known as blue-green algae or pond scum, has been found in the western part of Deer Lake. To view the sample location of the harmful algae bloom, visit the Health Unit website. Species of the algae capable of producing toxins were confirmed by the laboratory of the Ministry of Environment, Conservation and Parks.  The toxins in harmful algae can irritate the skin and, if swallowed, cause diarrhea and vomiting.

Residents of Deer Lake may be affected depending on their closeness to the site of the algae, the size of the lake, wind directions, water flow, and other environmental conditions that cannot be predicted or controlled. Due to the many factors involved, government authorities are unable to determine where and when there are no toxins. Users are recommended to use their judgment. For further details on the location of the algae bloom and sampling process, contact the Ministry of the Environment, Conservation and Parks at 705-497-6865 or 1-800-268-6060.

You can find out more about harmful algae at or by calling the Health Unit at 705-474-1400, ext. 5400 or 1-800-563-2808.

If you live near where the bloom was detected or where a bloom is visible, follow these safety measures:

  • Do not use the water. This includes: drinking, cooking, bathing, and brushing teeth. Note: Using a private water system or boiling the water will not destroy the toxins.

  • Do not swim and avoid water sports where there is harmful algae.Limit the amount of fish flesh you eat. Some toxins can build up in fish and shellfish.

  • Do not eat the liver, kidneys and other organs. Be careful not to cut the organs when filleting.

  • If skin contact does occur, wash with soap and water or rinse thoroughly with clean water to remove algae.

Quick Facts

  • Cyanobacteria – also called harmful algae, blue-green algae or ‘pond scum’ – are not really algae, but tiny bacteria.

  • Although usually hard to see, during hot weather they can grow rapidly to form a mass, called a bloom. Blooms continually change and are difficult to predict. Wind, temperature or sunlight could change where the bloom is located in the water.

  • Dense harmful algae blooms may make the water look bluish-green, or like green pea soup or turquoise paint. Very dense blooms may form solid-looking clumps.

  • Fresh blooms often smell like newly mown grass, while older blooms may smell like rotting garbage.

  • Even when a bloom has disappeared, toxins can persist in water bodies for a long time.

  • At high enough levels, the toxins may cause liver and nervous system damage.


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