Blue-green algae blooms plague Canada’s lakes this summer


Public health agencies across Canada have been working overtime this summer to educate the public about the proliferation of blue-green algae, otherwise known as cyanobacteria blooms, which can be toxic and highly resistant to treatment.

Cyanobacteria, which can rapidly increase in late summer and early fall to form a large mass or scum called a bloom, can cause skin irritation, rash, sore throat, sore red eyes, swollen lips, fever, nausea, vomiting and diarrhea, and has been linked to neurological conditions, including Amyotrophic Lateral Sclerosis (ALS) and Alzheimer’s disease.

In summer 2017, cyanobacteria discovered in a popular Victoria-area lake in British Columbia was suspected in the deaths of several dogs on Vancouver Island. That same year, research by the University of Alberta indicated that the cyanobacterial toxin microcystin had been found in 246 water bodies in Canada.

Blue-green algae can sometimes be spotted for its foamy pea soup-like appearance, and its more mature blooms can smell like rotten eggs. It often forms during hot, sunny weather in calm waters, and has become more prevalent in freshwater lakes over the last decade. According to B.C. officials, the bacteria is not a true algae but rather a photosynthetic bacteria.

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The toxic algae has also been prevalent in the Prairies, where much of the soil has naturally high levels of phosphorus. This contributed to Lake Winnipeg being named the Threatened Lake of 2013 by the Global Nature Fund, largely as a result of the blue-green algae in its waters. Leaking septic tanks can also prove to be a source of phosphorus.

In November 2017, the federal government announced an investment of $1 million to monitor northern Ontario waterways for cyanobacteria. The three-year “Remote Sensing: Waterway Algae Identification” project will help test the use of custom sensors and camera technology mounted on aircraft to produce real-time results on algae contamination in water bodies through waterway flyovers.

Additionally, the ATRAPP Project – Algal Blooms, Treatment, Risk Assessment, Prediction and Prevention Through Genomics, organized through the EDDEC Institute at Université de Montréal, began a $12.3-million research project into blue-green algae in fall 2016.

“It will allow [us to define new biomarkers, to create a tool box combining chemistry and genomics to identify toxicity risks, and to facilitate prevention and treatment of bloom episodes as well as toxic sludge treatment,” project organizers describe on their website.

Alberta Health Services has issued seven cyanobacteria advisories over the last month alone, the most recent pertaining to Moose Lake in Bonnyville.

Last week, Toronto Public Health issued a warning over algae discovered along the waterfront in Etobicoke, at the mouth of Mimico Creek and Humber Bay Park East.

In early July, warnings were also coming from the Saskatchewan Water Security Agency, which states that as much as 60% of all blue-green algae blooms contain toxins. “The blooms typically last up to three weeks and can be pushed around the lake or reservoir by the wind,” the agency states in its public advisory.

The Ontario government has released a factsheet for residents who want to learn more about cyanobacteria, which occurs naturally. It notes that the blooms can be particularly difficult to treat if they end up near a water supply. “Home treatment systems may not remove toxins and can get easily overwhelmed or clogged, so they should not be relied on,” the advisory warns. “Do not boil the water, or manually treat the water with chlorine or other disinfectants, as this could increase the toxin levels.”

Irena Creed, an ecosystems scientist from the University of Saskatchewan, has written about potential connections between climate change and the rise of cyanobacteria. Additional research on the subject from the University of Bristol has found evidence that blooms of all kinds may be a kind of cooling mechanism for the planet.

Cyanobacteria has also been found to deplete oxygen from the bottom of lakes, which can result in massive fish kills.


  1. I was just walking the trails arround Round Lake , Saskatchewan and the blue green algae is every shade of green turquoise and bright blue. Most of the ponds that used to be arround have dried up but one of the bigger ones is dark green. I remember it in Alberta 30 years ago. Heartbreaking.


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