Salting highways contaminates water.

• Position: Ecology

Staggering hurricane-related problems have commanded a bulk of the news coverage in recent months, but the northeastern U.S. faces a major--although far more subtle--ecological threat of its own, concludes a study by the University of North Carolina at Chapel Hill. Spreading salt on roadways to speed up melting of snow and ice has contaminated freshwater rivers, streams, lakes, and wells to an alarming degree. Moreover, detrimental effects of the practice are growing worse.

"Chloride concentrations are increasing at a rate that threatens the availability of freshwater in the Northeast," warns Lawrence E. Band, chair and Voit Gilmore distinguished professor of geography. "We found chloride concentrations were frequently up to 25% of the concentration of seawater in streams in Mary land, New York, and New Hampshire during winter. During summers, chloride concentrations remained up to 100 times greater than unaffected forest streams we used as controls."

The amount of salt in streams and other waterways increased as a function of impervious surfaces such as roads and paved driveways and often well exceeded tolerances for freshwater...