Road Salt in Winter: Are We Rubbing Salt Into a Wildlife Wound?

As the snow starts to fly, the familiar crunch of road salt underfoot returns. In Canada, about 7 million tons of road salt are applied to our walkways and roadways every year. But few of us recognize salt’s toxic effects on wildlife.

Road Salt

Every year, excess salt is washed into nearby stormwater collection and urban watersheds, a problem exacerbated by the city’s many impervious surfaces. As a result, our surface waters and groundwaters have accumulated chloride, posing serious risk for sensitive aquatic species. The Toronto Regional Conservation Authority (TRCA) has documented a threefold increase in mean chloride concentrations in our waterways since the 1970s.

Water sampled by the TRCA along trails familiar to many of TFN’s members exceed long-term safety thresholds for aquatic species (e.g., Etobicoke and Mimico Creeks, and Humber, Don and Rouge Rivers), affecting growth and fertility. Some areas even exceed short-term safety thresholds with potentially lethal results (e.g., Etobicoke, Mimico and Black Creeks, and Humber River). Insects with sensitivity to chloride have experienced substantial die offs in Toronto’s waterways with unknown effects for species dependent on them for food, including salmon species that run on the Humber. Seasonal spikes in chloride concentrations linked to excessive use of road salt have even supported the emergence of species normally found in salt water, such as the saltwater blue crab recently spotted in Mimico Creek.

How You Can Help

Wondering what you can do to support wildlife? While the City of Toronto has a salt management plan to limit the amount of salt it uses, you can help by observing some guidelines in your own use of salt:

  • Shovel early – you may not need to use salt at all
  • For remaining icy patches – use a traction aid such as sand or kitty litter, sprinkle salt ONLY where needed at 20 grams per square metre
  • Sweep up salt for later reuse after hazard has passed
  • Prevent icy buildup – redirect downspouts away from walkways/roadways, shovel snow from paved areas where runoff is likely

By making small changes in how we manage winter conditions, we can significantly reduce the harmful effects of road salt on our waterways and wildlife. Together, our efforts can help protect Toronto’s vibrant ecosystems for future generations.

Toronto Field Naturalists wishes to acknowledge this Land through which we walk. For thousands of years, the Land has been shared by the Wendat, the Haudenosaunee, and the Anishinaabe. Toronto is situated on the Land within the Toronto Purchase, Treaty 13, the traditional and treaty Lands of the Mississaugas of the Credit First Nation. This territory is also part of the Dish with One Spoon Wampum, a covenant agreement between Anishinaabeg, Haudenosaunee, Wendat peoples and allied nations to peaceably share the land and all its resources. Today, the Land is home to peoples of numerous nations. We are all grateful to have the opportunity to continue to care for and share the beauty of this Land.