Accessibility and Access Keys 
Skip to Content 
Nearly 50 Quebec lakes are infested with blue-green algae, spawning an unprecedented number of drinking-water bans across the province, environment ministry officials say.
The record contamination rate — a fivefold increase for this time of year over 2006 — has renewed calls for the government to bring in tougher legislation to contain the infestation.
Blue-green algae, known to scientists as cyanobacteria, normally grows during Quebec’s hot season in July and August. This year, dozens of lakes reported infestations early in the summer in the province’s most popular cottage regions, where hundreds of thousands of people spend their holidays.
The scourge has forced municipal officials to impose various restrictions on water drawn from affected lakes, ranging from drinking water bans to no-swimming orders.
Nursing homes, daycare centres and regional hospitals have had to take extra precautions to protect their water sources from toxins produced by certain species of blue-green algae that can irritate the skin, attack the liver or nervous system and be deadly for dogs.
The Eastern Townships are worst hit, with eight lakes reporting blue-green algae overgrowth, including the region’s jewel, lake Memphremagog.
Popular Brome Lake is also affected, as is Lac St. Louis off the West Island, a suburban area of Montreal.
And for the first time, Lake Edja in the Upper Gatineau is contaminated with cyanobacteria, which can also cause nausea, rashes and headaches in humans.
Officials with the province’s Environment Department say blue-green algae’s spread has taken on crisis proportions.
There’s growing pressure within the ministry to enact strict rules that would limit the algae’s main triggers, including phosphates found in detergents and fertilizers, officials told CBC’s French-language news service.
Hot temperatures, shoreline deforestation and leaky septic tanks are also considered aggravating factors and help cyanobacteria grow quickly.
The Outaouais Health Agency has instructed residents and cottagers to avoid using water from Gatineau’s Lake Edja for drinking, cooking, bathing or washing clothes, said spokesman Martin Saint-Louis.
“The people can swim in the lake, there is no problem,” he said.
However, he said anyone who sees an accumulation of algae, which appears as a scum on the surface of the water, should avoid swimming in that part of the lake.
Cowansville scrambles under water ban
In Quebec’s Montéregie region, about 12,000 people are under water bans because of the blue-green algae growth.
In Cowansville, authorities told people this week that tap water drawn from Davignon Lake is no longer potable because the municipality’s filtration plant can’t handle cyanobacteria.
The ban on drinking the water has left people and restaurants scrambling to find clean water.
Cowansville resident George Courville said he couldn’t even buy a cup of coffee on Thursday at his local McDonald’s.
“Then I came to work. One of my coworkers came in, and said last night, when she heard about it, she went down to Loblaws, and they were out, and everybody was running around,” he told CBC News.
“It was something like the ice storm,” he said, referring to the storm in 1998 that left millions without electricity. “People were just grabbing water bottles, throwing them in the car, and it was a mad rush.”
Municipal authorities said they’ll start distributing bulk water to residents on Friday.
Grand lac Saint-François
Petit lac Saint-François
Magog river and lake
Petit lac Lambton
Lac aux Cygnes
Lac des Iles
Lac Petit Lac Noir
St. Amour Lake
St. François Xavier Lake