The Seven Lakes region near Stony Point, NY. Rob Gross/Flickr
The quest for ice-free roads in winter is having a major impact on North American lakes: Some 44 percent of freshwater lakes in the U.S. Midwest and Northeast are becoming saltier, threatening drinking water, fisheries, recreation, irrigation, and critical aquatic habitats, scientists reported this week.
The new study, published Monday in the Proceedings of the National Academy of Sciences, attributed the “long-term salinization” of these lakes to the increasing use of road salt after snow and ice storms. Each year, transportation departments spread 23 million metric tons of sodium chloride-based de-icer on U.S. and Canadian highways and streets. The scientists found that if just 1 percent of the area around a lake was comprised of roadways or other impervious surfaces where salt might be applied, the water was extremely likely to have high levels of salt.
The scientists studied 371 freshwater lakes across the U.S. and Canada, all at least 10 acres large and with 10 years of recorded chloride data. By extrapolating their findings, they concluded that some 7,770 lakes in the North American Lakes Region — which stretches from Maine to Minnesota — could be at risk of rising salinity levels. They also said that many northern U.S. lakes could surpass Environmental Protection Agency-recommended levels of chloride in just 50 years.
“In the North American Lakes Region — where road salt is a reality — roads and other impervious surfaces within 500 meters of a lake’s shoreline are a recipe for salinization,” co-author of the study Kathleen Weathers, an ecosystem scientist at the Cary Institute of Ecosystem Studies, said in a statement. “We need to manage and monitor lakes to ensure they are kept ‘fresh’ and protect the myriad of services they provide.”
