Streams Are Getting Saltier

Person sprinkling salt on sidewalk steps

Whether you love it or could leave it, winter is coming. And with changing weather comes icy roads, sidewalks, parking lots and driveways.

To keep pedestrians and drivers safe, municipalities, businesses and homeowners apply salt or sodium chloride, to these icy surfaces. Salt works well to melt snow and ice, but did you know it’s toxic to fish and other aquatic life?

Brook trout fish swimming
Salt is toxic to fish like the watershed’s native brook trout. Photo credit: Jon Clayton

Once it washes off roads and other surfaces, salt eventually ends up in nearby streams or in groundwater. We measure the amount of salt in the environment by tracking levels of chloride. In recent decades we’ve seen chloride levels increasing in streams across the Credit River Watershed.

Stream chloride levels peak in the winter, sometimes reaching as high as 25 times the amount that is safe for aquatic life. Some of our groundwater monitoring wells also have high levels of chloride.

Besides being toxic to fish, aquatic insects and frogs, chloride is also harmful to wetland plants. Sensitive plants may get replaced by salt-tolerant ones, reducing wetland biodiversity.

A graph showing choloride concentrations increasing over time
The blue dots show chloride levels over time in the Credit River. In the 1990s, chloride levels rose above safe levels for aquatic life.

While road salt is the biggest source of chloride in the watershed, there are other ways chloride gets into the environment. Dust suppressants on gravel roads and some fertilizers also contain chloride.  Water softeners release salt that eventually ends up passing through a wastewater treatment plant or septic system. But unfortunately, salt doesn’t get removed in the process.

We can all play a role in reducing the amount of chloride that goes into the environment. Learn more about chloride levels in the watershed and how you can help protect our streams and groundwater – check out our Integrated Watershed Monitoring Program StoryMap Collection.

You can also view chloride levels across the watershed in real-time. Share your thoughts with us on LinkedIn.

By: Adrienne Ockenden, Specialist, Watershed Monitoring

Comments (8)

  1. Salt is ABSOLUTELY a problem. But what’s the better answer?

    -Homeowners should shovel sidewalks more diligently, rather than just dumping salt everywhere. This wouldn’t *eliminate* the need for salt, but would reduce it.
    -Municipalities could use sand for improved traction, rather than salt for melting. But sand can clog storm sewers, and is also not great for our lakes and rivers

    You are highlighting a very real problem, but offering no ideas as to a solution. “We can all play a role in reducing the amount of chloride that goes into the environment.”… ummm… okay…?

    1. Hi Kevin, thanks for your interest. Check out some suggested actions on our IWMP StoryMap Collection – click on the Stream Chlorides story to learn more.

  2. Thank you Adrienne for your article regarding rock salt. We walk along Mineola Rd East in Port Credit each winter day this year and have seen absolutely no change (from previous years)in the amount of salt out on the sidewalks . One day our dog writhed in pain as we had forgotten her boots. What can we do to educate the folks laying too much salt!!!!!!! I call 311 each year.
    Thanks
    Laurel

    1. Hi Laurel, tanks for your comment. We have several suggestions for how reduce chlorides, including advocating and educating. Check out some suggested actions on our IWMP StoryMap Collection – click on the Stream Chlorides story to learn more

    1. Hi Jessi, thanks for your interest. Check out some suggested actions on our IWMP StoryMap Collection – click on the Stream Chlorides story to learn more.

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