The Great Lakes | WWF-Canada
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The Great Lakes Basin—composed of Lakes Superior, Huron, Michigan, Ontario and Erie, together with the thousands of tributaries that feed it—is the one of the world’s largest connected freshwater ecosystems, containing about 20 per cent or one fifth of the world’s fresh surface water.

Not only is this globally significant ecosystem at the heart of Canada’s economy, it is teeming with life. Within its diverse ecosystem we find turtles, moose, wolves, bald eagles, waterfowl and more than 200 species at risk.

A watershed under threat

For everything that the Great Lakes watershed provides, it is unfortunately one of the most threatened watersheds in Canada.

WWF’s Watershed Reports found that is faces very high threats from pollution, habitat fragmentation, overuse of water and invasive species, jeopardizing the health of wildlife – and people too. But perhaps even more alarming is the fact that we don’t collect enough data to know just how much damage all this stress is causing.   

Where the water flows, the salt goes

In southern Ontario, rapidly increasing levels of chloride (Clˉ), caused by the excessive use of road salt in the winter, is having a devastating impact on the freshwater ecosystems of the Great Lakes.

In the winter we use too much salt, often 30 times more than what is needed for safe roads and walkways. The salt spread on our pavement doesn’t disappear with the snow and ice, and instead it seeps into soil or flows from roads and parking lots into sewers and then into makes its way into our creeks, rivers, wetlands and lakes. In the winter, some urban creeks are becoming as salty as oceans (19 000 mg/L Clˉ) and may maintain levels that are dangerous for wildlife (>120 mg/L Clˉ) year-long. Chloride levels spike during snow ice and rain events, even in the fall.

The Great Lakes Basin is not a coastal ecosystem adapted to fluctuating salt levels. 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 species to people.

We want the Great Lakes to be Less Salty

WWF-Canada is working with conservation authorities, ENGOs, legal bodies, private contractors, academia, the City of Toronto and government to pilot new techniques and technologies for road salt application that ensure public safety and environmental health. Through training, certification, education and reduction we can protect freshwater ecosystems and wildlife as communities grow.

As part of this work, WWF-Canada has asked the Ontario government to take action to reduce the amount of salt entering our freshwater.
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Common loon with pumpkinseed fish lepomis gibbosus
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Water health in Canada

WWF-Canada’s Watershed Report captures for the first time the state of all 25 of Canada’s watersheds through assessments of both health and the stresses we place on freshwater ecosystems.


	© World Wildlife Fund Canada
Anthony Merante
Freshwater specialist
	© WWF

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. 


Studies in the Great Lakes have found higher levels of microplastics than in ocean samples. Help stop the flow of plastics.