Just like too much salt in our diet can be bad for our health, too much salt on roads and sidewalks is bad for plant and animal life in and along waterways.
Wintry weather means the Pennsylvania Department of Transportation (PennDOT) and local municipalities are out in force clearing roadways of snow and ice.
Traditional road deicers are usually a form of salt. When applied in wintry conditions they can eventually be swept away by rain or thaw from warmer temperatures, forming a bad brew.
Pennsylvania is among northern states in what is referred to as the Salt Belt, named for its frequent use of salt on roadways to control snow and ice.
The University of Toledo found the use of deicing salt in the United States has tripled in the last 50 years.
Since 2020, PennDOT reports applying nearly 600,000 tons of salt to state roads. Many more tons were likely added by local municipal road crews.
Add to that the millions of gallons of liquid salt, called brine, applied to prevent ice formation, and it becomes clear that the risks of contaminating freshwater streams and habitats from treated snowmelt can be high.
In many parts of the country, salting roads is a tradition as old as the automobile.
The salt helps melt snow and ice by lowering their freezing point to below 32 degrees Fahrenheit.
The salt dissolves in the melted snow and ice, where it either accumulates in nearby soils or with rain or thaw finds its way to the nearest waterbody.
Scientists call this “freshwater salinization syndrome.” It’s a fancy term for what happens when salt concentrations become so high they can be toxic to fish and other important aquatic life.
Salt in rivers and streams can also cause big problems for important infrastructure by corroding bridges and pipes, polluting drinking water supplies, and leaching heavy metals and nutrients.
Recently, a study found rivers and streams across the nation are getting saltier, including in Pennsylvania.
Researchers analyzed five decades of data from 232 U.S. Geological Survey river and stream monitoring sites. They found that salt concentrations had increased by 37 percent.
A study of six urban and suburban streams in southeastern Pennsylvania spanning 20 years concluded that all the streams showed signs of increasing salt pollution, largely from road runoff and snowmelt.
In a separate study, a section of Haines Run in suburban Montgomery County reported a spike in chloride levels from less than 31 parts per million to 290 parts per million just a couple of days after snowmelt.
That’s about a 1,700 percent increase.
Chloride concentrations above 230 parts per million are generally considered toxic for aquatic life.
Less toxic alternatives to salt have been formulated, but none to date are as cost-effective as traditional salts.
While researchers continue to search, the best way to reduce the threat of excessive salt is to better manage application.
It is important to use only what is needed and at the times it will work best and with high quality equipment that reduces waste.
Around the home we can do our part by not overusing salt on driveways, walkways, and other slick surfaces.
Products containing calcium or magnesium chloride are common alternatives. Both are considered generally less toxic than rock salt (sodium chloride) which can have impurities or added cyanide as an anticaking agent.
Of the current chemicals in use, the least toxic alternative are products with calcium magnesium acetate. Be sure to use caution when selecting an alternative.
Sand is a popular go-to alternative to chemicals for improving traction on slick surfaces. But it too can find its way into streams where it can smother habitat important to fish and other aquatic life.
This time of year, let’s remember that snow is not our enemy.
Historically, parts of Pennsylvania get a lot of snow. Each spring, the melting snow seeps deep into the ground.
There it becomes a primary source of clean, cold water feeding our streams during dry summer months.
It helps keep iconic critters like the Eastern hellbender and our native brook trout stay happy and healthy throughout the year.
Winter Salt Awareness Week Webinars
Later this month we’ll mark Winter Salt Awareness Week 2025, Jan. 27-31. The national effort aims to raise awareness around salt pollution and reduction solutions.
The Stroud Water Research Center in Chester County is Pennsylvania’s Regional Partner.
Click Here to learn more about salt pollution and to register for livestreams highlighting problems and solutions.
For more on Chesapeake Bay-related issues in Pennsylvania, visit the Chesapeake Bay Foundation-PA webpage. Click Here to sign up for Pennsylvania updates (bottom of left column). Click Here to support their work.
Also visit the Keystone 10 Million Trees Partnership to learn how you can help clean water grow on trees.
CBF has over 275,000 members in Bay Watershed.
Harry Campbell is Pennsylvania Science Policy and Advocacy Director, Chesapeake Bay Foundation
Upcoming Salt Events:
-- Penn State Extension Hosts Jan. 29 Webinar On Ice Melter Impacts And Reduction Strategy [PaEN]
Resource Links:
[Posted: January 9, 2025] PA Environment Digest
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