Salting a snowy and icy road is standard procedure for most cities and towns. Where that salt ends up is rarely a concern, but according to new research it is concerning because the salt washes into rivers and streams and remains highly toxic through the rest of the year. Scientific American reports that in states like Wisconsin, where salt is used liberally to clear icy roads, the levels of sodium chloride in rivers, streams, and lakes is as much as 15 times higher than the federal level suggests to protect fish, amphibians, and small crustaceans.

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In the study, seven of 20 U.S. rivers approach or exceed the EPA’s guidelines for protecting aquatic life. Four of the rivers are in Wisconsin, one is in Ohio and two are in Illinois. Road salt remains in rivers for years, according to Sujay Kaushal, an associate professor at the University of Maryland, and can leach into groundwater affecting the drinking water for those nearby. “Even if they quit applying salt now, it would take decades for it to be removed from the system,” Kaushal said.

RELATED: Wisconsin uses cheesy water to de-ice wintry roads

The federal government, however, does not regulate road salt or track its usage, according to an article in Seven Days Vermont. Why? Road salt is cheap, to the tune of about $65 a ton in Michigan, according to the Detroit Free Press, and that’s up from $44 in 2013. Salt is also effective at keeping roads safer during the winter months, as it lowers the freezing point of water and keeps ice and snow from sticking to the road. To make matters worse, cyanide compounds are also added to salt on occasion to keep it from caking.

Cities like Madison and Milwaukee, Wisconsin, have explored greener alternatives to salting with varying levels of success, including sand and beet juice. Invariably, some amount of salt was still required to clear a road. It’s also worth noting that in places like Vermont and Alaska, studded tires are permitted, which reduce the amount of road clearing required for general travel. But in some states like Wisconsin where winters are long and road salt use is heavy, studded tires are banned due to the damage they can do to road surfaces.

Via NPR

Images via hrobertsson, Jeroen Kranssen and Carol Munro, Flickr Creative Commons