Winter Chloride Watch

In the winter months, salt is commonly spread on roads to prevent the build-up of snow and ice. Across the United States, more than 20 million tons of salt is spread on roads, and while salt helps keep driving conditions safe, it is extremely corrosive to infrastructure and negatively impacts wildlife. In the State of Illinois, 475 stream miles were listed as “impaired” in 2018 due to elevated levels of chloride from road salt.

It is obviously important to keep our roadways safe, but when the snow and ice melts the salt dissolves and then travels into our freshwater resources. Chloride levels can be particularly elevated in urban and suburban areas leading to concentrations that are toxic to many fish and invertebrate species. Research conducted by scientists at National Great Rivers with the help of our Winter Chloride Watchers showed that chloride concentrations in the St. Louis region were unsafe for aquatic animals in watersheds where roads covered at least 5% of the land surface.

Monitoring chloride levels in your local area is easy to do and takes very little time to test the water and send your information to our scientists. If you are interested in becoming a Winter Chloride Watcher, please contact the National Great Rivers RiverWatch staff at riverwatch@lc.edu