An increase in the use of salt for road deicing over the past two decades may be contributing to increased levels of chloride — a component of salt — in streams and groundwater, where it can have an adverse effect on drinking water and wildlife, according to a new study from the U.S. Geological Survey (USGS). The USGS study, released in September, found chloride levels above the recommended federal criteria established to protect aquatic life in more than 40 percent of the urban streams tested in the study.

However, few of the tested areas had chronically high chloride levels, and most of the high chloride levels discovered by USGS were related to major storm events requiring exceptionally high road salt use in urban areas, not the result of routine discharges from deicing programs, according to the Alexandria, Va.-based Salt Institute.

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