The changing climate is making Maine’s winter roads more treacherous, but the rock salt used to clear them is polluting rivers and streams throughout the state. That’s the tension at the heart of a new report on winter road maintenance.

The report, from University of Maine researchers in collaboration with the Maine Department of Transportation, builds on a similar study from a decade ago, and shows that the amount of salt in both freshwater and groundwater is increasing, putting life in those waterbodies at risk.

But rising as well is the amount of ice, sleet and freezing rain we get every winter. It will take coordination between local and state officials to make sure that keeping roads safe doesn’t imperil important waterways across Maine – and even then, in some areas, people may have to change their expectations for traveling during a winter storm.

As the report notes, rock salt, affordable and easy to handle, is the most commonly used winter road treatment in Maine, where about 493,000 tons of the stuff was used in the winter of 2019-20 – 787 pounds for every Maine resident, or 11 tons per lane mile of road.

There has been a steady rise in salt use over the last 15 years, as climate change has brought more-messy storms – instead of the dry snow that is so easily plowed away – and people have become accustomed to getting around regardless of the weather.

The salt keeps the road surface from freezing, but a lot of it is washed into the water. In Minnesota, a study found that 70 percent of the salt used every year in and around Minneapolis and St. Paul stayed in the watershed.

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So it’s no surprise that, according the Maine Department of Environmental Protection, 20 streams in Maine are chloride impaired, including the Bond Brook and Kennedy Brook watersheds around Western Avenue in Augusta, and the Long Creek area around the Maine Mall.

Once a stream is impaired, it takes a lot of effort to fix. If Maine is going to allow these areas to heal, and keep others from getting worse, it’ll have to better manage winter road maintenance.

That’s going to take a high degree of coordination. The DOT takes care of only about 20 percent of Maine roads, with the rest under the care of local governments. They’ll need resources, information and guidance to change the way they do things now.

The report suggests stronger links between university research, environmental monitoring and road-maintenance workers. That would help the people on the ground locally better understand how each individual storm and adjust the amount and timing of salt as needed.

Also, the DOT should make sure local operations are aware on the latest research and training for how to apply road salt. States across the country, including New Hampshire and Minnesota, are confronting the issue the same as we are, and we can learn a lot from their trials.

On roads near vulnerable streams, however, there may be no choice but to cut back salt use to the point where it affects road safety, at least to some degree, making it difficult to drive during or immediately after a storm.

It’s a tough trade-off, and one that a lot of communities are not used to making. Residents need to understand the damage that road salt is doing to their environment, and what that means for the health and well-being of their community.

Otherwise, people will continue to demand that their road be clear, even in a storm, and Maine streams will continue to fill up with salt.


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