MWMO Environmental Specialist John Mueller demonstrates how to use a multiparameter sonde to test for conductivity and salinity — two indicators of chloride — in a sample collected from a stormwater outfall.

In the spring, melting snow and ice carries chloride from road salt and deicing chemicals through the stormsewer system into local waterbodies. Chloride is toxic to freshwater fish and other aquatic life, and there is no practical way to remove it. Nearly 365,000 tons of road salt is used in the Twin Cities metro area every year.