Toxic Blue-Green Algae Has Been Found Across Ontario This Summer & Whatever You Do, Don’t Touch It

It's toxic to humans and dogs!

Creator

Blooms of toxic blue-green algae have been spotted all over Ontario this summer, and they can have negative effects on humans and pets.

Contact with blue-green algae from swimming, drinking or eating fish from water where blue-green algae blooms can be found can cause itchy, irritated eyes and skin, headaches, fever, diarrhea, vomiting and even liver damage in serious cases, according to Niagara Region Public Health.

Blue-green algae are microscopic bacteria that can be found in late summer and into fall in freshwater lakes, rivers, bays, streams, and ponds.

You can recognize blue-green algae blooms by their distinctive colour, which can resemble "turquoise paint." Heavy blooms often look clumpy and fresh blooms can smell like "newly mown grass," whereas older blooms can smell like "rotting garbage," according to the Ontario government.

Recent blue-green algae sightings

One of the most recent spottings of the algae was in Black Bay on Lake Superior. The water sample was collected on July 9, according to Thunder Bay Health Unit, and even though no toxin analysis was conducted, "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."

Two Island Lake and Hazelwood Lake Conservation Area both reported blue-green algae in June 2021, with toxin levels below the Ontario drinking water standard.

Niagara Region Public Health closed down the beach at Charles Daley Park in Lincoln on June 29 due to blue-green algae at the beach and in an outflow connected to it. It has since reopened.

In late May 2021, a dog reportedly died from contact with blue-green algae in Renfrew, Ontario, after swimming in a creek about 10 kilometres west of the town, off Highway 60.

If you spot a bloom of algae and suspect it is blue-green algae, your best bet is to steer clear of it and contact the ministry's Spills Action Centre at 1-800-268-6060.

This article's cover image was used for illustrative purposes only.

  • Brooke Houghton (she/her) was a Toronto-based writer for Narcity Media. Brooke has written for publications such as blogTO, Post City, Vitalize Magazine and more.

Gas exposure at pool linked with mixing chemicals

City spokesperson says Crystal Pool is safe again, but remains closed until Tuesday

Gunman at Mexico pyramids kills Canadian tourist

Canadian tourist killed, another injured after gunman opens fire at Mexico pyramids

Alberta to do away with twice-a-year time change

Alberta's government says it will do away with twice-a-year time change

Poll suggests more Tory voters now want new leader

Poll suggests more Conservative voters now want to replace Poilievre as leader

Ontario to sell $29-million jet bought for Ford

Ontario to sell $29-million jet bought for Premier Doug Ford after backlash

Canada, Mercosur look to sign trade deal in 2026

Canada, Mercosur aiming to sign free trade deal this year: Brazilian official