Road salt runoff threatens water quality, study finds

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Capital News Service

LANSING — Winter road safety is adding salt pollution to Great Lakes streams, according to a recent federal study.
The U.S. Geological Survey examined approximately 100 streams in Michigan and 18 other northern states for road salt and other sources of chloride.
A quarter of the 52 streams tested in Great Lakes states had chloride levels that exceeded federal standards designed to protect drinking water supplies.
The Clinton River at Sterling Heights had a reading of about 300 milligrams per liter, which is higher than federal drinking water regulations for chloride. Levels higher than 250 milligrams per liter give water a salty taste, the study said.
The other three Michigan streams tested were within federal limits. They are River Raisin near Manchester in Washtenaw County, the Black River near Jeddo in St. Clair County and the Peschekee River near Martins Landing in Marquette County.
Excessive chloride can also be harmful to fish, plants, insects, worms and macro-invertebrates, said Kevin Cronk, a monitoring and research coordinator for the Tip of the Mitt Watershed Council, a Petoskey-based northern Michigan group that advocates for water quality.
The organization works in parts or all of Emmet, Cheboygan, Kalkaska, Grand Traverse, Antrim, Otsego, Presque Isle, Charlevoix and Montmorency counties.
Chloride has increased in all lakes and streams in northern Michigan, Cronk said, and high readings usually occur in highly urbanized areas.
Winter road safety accounts for 40 percent of the use of salt in the United States, the study said, and most streams that tested high are near where salt and other chemicals are used to deice roads.
Highway officials reported using from as little as 10 tons to as much as 30 tons of salt per one mile of road lane in all of the states surveyed.
Michigan road and highway agencies used within the average range.
In other Great Lakes states, the study found New York used 70 tons of salt to deice the Croton Watershed, an area north of New York City. Harrison, Ohio used the least amount — only six tons per lane mile.
The Geological Survey said other sources of chloride in streams and groundwater include landfills, drinking and wastewater treatment, fertilizers, septic systems, animal wastes and natural sources in geologic deposits.
Cronk said chloride is a good indicator of human activity and population increases. High levels may also signal that harmful chemicals leaking from cars are ending up in streams.
“The reason we monitor chloride is to gauge the increasing development in north Michigan,” he said. “If you have a lot of road salt coming into the lakes and streams, that shows us what else is coming into the lakes and streams.”
Rachael Gleason writes for Great Lakes Echo.

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