Salt for Snow and Ice: Effects on Waterways Not Very Nice

I recently came back from a trip to Pittsburgh. My car and windshield were caked in dried road salt.

While this year has been relatively snow-free for much of the Keystone State, state and local road crews have been actively adding salt when the threat of wintry weather hits.

When I was a kid growing up in the Back Mountain area of Luzerne County, I remember snow covering the ground most of the winter.   

Pennsylvania is part of what’s called the Salt Belt, states that use a lot of salt on roadways to control snow and ice.

This winter, the state Department of Transportation (PennDOT) has budgeted over $212 million for clearing roads of snow and ice. Last winter, they applied over 801,000 tons of salt and over 525,000 tons of anti-skid materials to state roads. Thousands more tons were likely added by local municipal road crews.

For storm events last winter, PennDOT also pretreated roads with more than 10.3 million gallons of salt brine. The water in the brine evaporates and the remaining salt helps prevent ice from forming a strong bond with the road surface. 

Road salt is an unpurified version of good old table salt, sodium chloride. It helps melt snow and ice by lowering the freezing point below 32 degrees. 

Although the road salt seemingly disappears after doing its job, we often see it again caked onto our cars when the snowmelt dries. But it also accumulates in roadside soils and eventually can flow into the nearest river or stream.     

A study published in the Proceedings of the National Academy of Sciences suggests that salt ions are changing the chemistry of freshwater streams across the nation, including in Pennsylvania. Researchers analyzed five decades of data from 232 U.S. Geological Survey river and stream monitoring sites. They found that salt ions increased in rivers and streams that make up 37 percent of the contiguous United States. 

For our creek critters, salty streams are a toxic brew. But road salts also pollute nearby soils, kill trees and plants important for wildlife, corrode bridges, and pollute drinking water supplies. 

Studies by the Susquehanna River Basin Commission and others are gathering scientific data on the extent of the problem in Pennsylvania’s rivers and streams.   

My grandmother would often say “Moderation is key.” It applies to using road salt too. The right amount helps keep our roads safe, but too much pollutes our water, kills plants, and degrades our infrastructure.    

Around the home we can do our part by not using, or using far less, salt on driveways, sidewalks, and walkways. 

Safer alternatives, like calcium magnesium acetate (CMA) exist, but no perfect replacement has yet to emerge.  

If you use a deicer, be aware that some store-bought salt products may have toxic impurities or additives, like forms of cyanide. So read the label. 

Sand or even kitty litter are popular go-to alternatives to salt for improving traction on slick surfaces. But they too can find their way into streams where they can smother habitat important to fish and other aquatic life.

Regardless of which type of snow or ice melt you choose, proper application is key to preventing negative impacts. 

Frankly, snow is a good thing. Snowmelt is a big source of  cold groundwater feeding into our streams during the dry summer months  The cleaner it is, the happier and healthier iconic critters like our native brook trout and the Eastern hellbender will be.

So, as we await the next big one, remember that snow is also a good thing and obliterating it with salts can come at a big cost.  

Harry Campbell 90x110

Harry Campbell

Director of Science Policy and Advocacy, CBF

[email protected]

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