Blue-Green Algae Identified at the northeast portion of Open Bay on Lac des Milles Lacs

Blue-Green Algae photo

October 11, 2022 - The Ministry of the Environment, Conservation and Parks has confirmed the presence of blue-green algae in a water sample collected at Open Bay on Lac des Mille Lac on October 04, 2022 (located approximately 120 kilometres west of the City of Thunder Bay). The MECP is conducting toxin analysis on the water sample. However, it is important to remember that water should be avoided whenever a blue-green algae bloom is present, and for about 2 weeks after it has dissipated, regardless of the toxin analysis results because blue-green algae can turn toxin production on and off in response to environmental conditions. Toxin analysis typically takes 4 to 5 business days and updates will be provided on the TBDHU website.

When blue-green algae is present in water, it is important to avoid drinking the water, using it for household purposes, or swimming in it. Keep pets away from the water as well, as their smaller size and propensity for drinking lake water makes them more vulnerable.

Blue-green algae are microscopic organisms that are naturally present in lakes and streams. They are usually present in low numbers but can rapidly increase in warm, shallow, surface water that gets a lot of sun. When this happens, they can form blooms that make the water look like green pea soup or turquoise paint. When the bloom is very large, the harmful algae bloom may form scum or solid-looking clumps on the water surface. Some blue-green algae blooms produce toxins than pose a health risk to people and animals when consumed, inhaled, or even from skin contact. If contact with a blue-green algae bloom does occur, wash with soap and water and rinse with clean water to remove the algae.

Blue-green algae blooms in lakes in our region have been relatively uncommon, historically. However, with rising climate and water temperatures they may become more common.

If you spot a suspected blue-green algae bloom, report it to the Spills Action Centre at 1-800-268-6060.

For more information on blue-green algae blooms, please visit the Ministry of the Environment, Conservation and Parks website at:

If you have questions, please contact the Thunder Bay District Health Unit at 807-625-5900 to speak with a public health inspector.


For more information: Health Unit Media

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