Tech Digest

Researchers find road salt affects Minnesota lakes and rivers

UNIVERSITY RESEARCHERS studied 39 lakes, three major rivers and their tributaries, and numerous wells around the Twin Cities and found about 70 percent of the road salt being applied in the metro area during the winter is retained in the watershed.

Civil engineering professor Heinz Stefan is leading a research team to study the effects of road salt on local water quality. Research showed 70 percent of the salt applied to de-ice roads during the winter in the metro area stays in the area.

Heinz Stefan, a civil engineering professor at the University’s St. Anthony Falls Laboratory who led the study for the Local Road Research Board, found salt concentrations in the water has increased over the last 24 years. While current salt levels aren’t harmful, the research team says increases in sodium and chloride have been shown to decrease biodiversity in wetlands and reduce fish populations.

More efficient use of road salt could help lessen the impact on the environment and save money. The Minnesota Pollution Control Agency has mounted a training program to get road crews to apply salt more judiciously. Highway crews are using various techniques to cut down on the salt. They often lay down a thin layer of salt before a storm, so ice doesn’t get a chance to form in the first place. They also mix salt and sand with water so it will stick better. The program is working at the University of Minnesota. Since training began Civil engineering professor Heinz Stefan is leading a research team to study the effects of road salt on local water quality. Research showed 70 percent of the salt applied to de-ice roads during the winter in the metro area stays in the area. two years ago, workers have reduced the amount of salt they use by 41 percent, saving more than $50,000 in one year.

“This is a wake-up call. If we keep on doing this for another 50 years, we may have a significant problem,” Stefan said. “Certainly if groundwater becomes saline, when we use that water, we may have to treat it at significant cost.