Careful Use of Road Salt Could Help Lakes, Save Money

MINNEAPOLIS - Road salt used during the winter is making lakes and rivers in Minnesota saltier, which could affect drinking water, fish and aquatic plants, according to new research at the University of Minnesota.

Researchers looked at 39 lakes, three major rivers, 10 tributaries and several observation wells, and found roughly 70 percent of the road salt used in the Twin Cities metro is retained in the state's watershed.

"Nobody has asked the question of where the salt ultimately goes after the winter season is over," lead researcher Heinz Stefan said. "Our study has been concerned with that question in particular."

Nearly 350,000 tons of sodium chloride, or road salt, are used in deicing in Twin Cities metro roads every year, according to the study.

Researchers found salt concentrations in 39 metro lakes have increased over the past 22 years, following a similar trend in road salt purchases by the state of Minnesota. Both show a marked increase from 1984 to 2005, which if continued would double salinity in these lakes in about 50 years.

The study compare those concentrations with a near zero level in the 1950s, when road salt application began.

The study suggests better training of snow plow drivers and more judicious use of road salt could help lessen the impact on water resources and save the state money.

Applying road salt to pavement when temperatures are below 15 degrees is generally not effective, the study said. At higher temperatures, researchers suggest using only one to three cups of salt per 1,000 square feet.

These recommendations have been applied at the University of Minnesota, where two years ago, the university has reduced use of road salt by 41 percent and saved more than $50,000 in the first year.

More info: www.safl.umn.edu
MPCA: www.pca.state.mn.us/programs/roadsalt.html