U.S. Addiction To Road Salt Endangering Water Quality

It's useful during the icy days of winter, but road salt may have long-term effects on the water supply.

The U.S. Geological Survey (USGS), a federal agency, published a report in December on the rising use of road salt in the journal Science of the Total Environment.

The upshot? "Average chloride concentrations often exceed toxic levels in many northern United States streams due to the use of salt to deice winter pavement, and the frequency of these occurrences nearly doubled in two decades," the USGS said in a summary of the study.

Scientists studied water quality from 19 streams and 30 monitoring sites.

"Twenty-nine percent of the sites exceeded the [EPA's] chronic water-quality criteria (230 milligrams per liter) by an average of more than 100 days per year from 2006 through 2011, which was almost double the amount of days from 1990 through 1994," USGS reported.

"In 16 of the streams, winter chloride concentrations increased over the study period. In 13 of the streams, chloride concentrations increased over the study period during non-deicing periods such as summer. This finding suggests that chloride infiltrates the groundwater system during the winter and is slowly released to the streams throughout the year," the summary continued.

Vox described potential concerns surrounding this trend: "When all that salt dissolves and washes away, it steadily accumulates in rivers and streams. In some areas, that makes drinking water saltier (bad news for people on low-sodium diets). All that salt also kills off fish, plants, and amphibians. Other times, moose and elk get attracted to the salt and wander onto roads, raising the risk of crashes."

Steve Corsi, USGS scientist and lead author of the study, spelled out the danger of the nation's increasing reliance on road salt.

"Some freshwater organisms are sensitive to chloride, and the high concentrations that we found could negatively affect a significant number of species," he said. “If urban development and road salt use continue to increase, chloride concentrations and associated toxicity are also likely to increase.”

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