© Anthony Merante Great Lake with Toronto skyline


The rivers and creeks of the Great Lakes are under threat from increasing levels of chloride. WWF-Canada is working to make the Great Lakes #LessSalty.

A Watershed Under Threat

The Great Lakes Basin is a big deal in the freshwater world. Lakes Superior, Huron, Michigan, Ontario and Erie and the thousands of tributaries that feed them make up one of the world’s largest connected freshwater ecosystems, holding about one-fifth of the world’s fresh surface water. At the heart of Canada’s economy and teeming with life, Canada’s Great Lakes support a diverse ecosystem including turtles, moose, wolves, bald eagles, salmon, walleye, trout and more than 200 species at risk. For everything that the Great Lakes watershed provides us, it is also one of the most threatened water systems in Canada.

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What is the Issue?

In southern Ontario, rapidly increasing levels of chloride (Clˉ), caused by the excessive use of road salt (sodium chloride, magnesium chloride, calcium chloride) in the winter, is having an impact on the lakes and rivers that flow into Lake Ontario. The salt seeps into soil or flows from surfaces into sewers, making its way into creeks, rivers, wetlands and lakes. Road salt’s chloride component is toxic to freshwater ecosystem and life. All this over-salting has led to rapidly increasing levels of chloride in southern Ontario waters, where it’s having a devastating impact on the Great Lakes ecosystem.

Some urban creeks are even becoming as salty as the ocean during spring and winter. Freshwater species such as salamanders, frogs and fish can’t survive in water that’s too salty and are disappearing. In groundwater-dependent communities, salt also ends up in the drinking water, extending the threat from wildlife to people.

Great Lakes Chloride Summer Hot Spot Map

The map shows chloride levels in Southern Ontario. Data was collected during summer months (May-October) from 2007-2011 and 2012-2016. As the colour gets darker, the area is more likely to have unhealthy levels of chloride. High chloride levels pose a threat to freshwater wildlife and ecosystems.

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We Want the Great Lakes to Be #Lesssalty

What WWF-Canada is Doing

The Great Lakes Basin faces very high threats from pollution, habitat fragmentation, overuse of water and invasive species that are jeopardizing the health of wildlife and people. WWF-Canada is working with conservation authorities, environmental non-governmental organizations, legal bodies, private contractors, academics, the City of Toronto and other governments to pilot new techniques and technologies for road salt reduction use that focus on public safety and environmental health. As part of this work, WWF-Canada has asked the Ontario government to take action to reduce the amount of salt entering our freshwater ecosystems.

See our request for Provincial Water Quality Objective on Chloride.

See our comments on the Ontario Government’s “Preserving and Protecting our Environment for Future Generations: A Made-in-Ontario Environment Plan.”

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What You Can Do

North American beaver

Adopt a Beaver


Testing Freshwater

Generation Water Tech Challenge

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Shoreline Cleanup Participants


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© Terry Kelly / WWF-Canada landscape of freshwater

Learn More about our Freshwater Work

WWF-Canada is working towards a future where all Canadian waters are in good condition, by building water-resilient communities, bringing big-water data to decision-making tables and creating a culture of water stewardship across the country.

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