Blue-Green Algae

Blue-green algae (BGA) are microscopic organisms found naturally in lakes and streams. They are usually found in low numbers but can rapidly increase in warm, shallow, surface water that receives a lot of sun. When this happens, they can form blooms that make the water look like green pea soup or turquoise paint. Some blue-green algae produce toxins that pose a health risk to people and animals.

When BGA 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 there have been incidents in other jurisdictions where pets have died after drinking water containing blue-green algae.

If contact with a bloom does happen, wash with soap and water and rinse with clean water to remove the algae.

Testing for toxins can identify if the bloom is producing toxins at the time the sample was taken. However, a negative result does not mean that the bloom is not harmful. Blue-green algae can turn toxin production on and off in response to a complex suite of environmental factors. This means that toxins may be produced at different times during a bloom event.

BGA bloom in lakes in our region are rare BUT water temperatures are rising.


If You Suspect a BGA Bloom

If you spot a suspected blue-green algae bloom, report it to the Ministry of Environment's TIPS line: 1-866-MOE-TIPS (663-8477).


Current Blue-Green Algae Notifications

Location Water Sample Date Date BGA Bloom Identified
Kenogamisis Lake September 18, 2023 September 21, 2023
Hazelwood Lake - Public Beach Area August 24, 2023 August 30, 2023
West Loon Lake August 24, 2023 August 28, 2023
Surprise Lake August 13, 2023 August 16, 2023
Lake Superior near Scott Dr. (Shuniah) July 25, 2023 July 28, 2023
Surprise Lake June 19, 2023 June 21, 2023
Trout Lake June 30, 2023 July 6, 2023
Icarus Lake July 2, 2023 July 6, 2023

Note: For previous year blue-green algae notifications, visit Blue-Green Algae Historical Results



If you have questions, please contact the Thunder Bay District Health Unit at 807-625-5900 or toll-free at 1-888-294-6630 to speak with a public health inspector. The following links provide additional information.

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