Road salt spreading into our water

Rain and melting snow in the Twin Cities have flushed away road salt residue from hundreds of streets and tens of thousands of cars. But that might not be a good thing.

Now a University of Minnesota study estimates that 70 percent of the deicing salt used on metro-area roadways does not travel far when it drains off the pavement. It gushes into area wetlands and lakes and seeps into groundwater, and it is making them saltier with each successive year. About 30 percent goes to the Mississippi River.

"This is a wake-up call," said Heinz Stefan, a civil engineering professor at the university's St. Anthony Falls Laboratory. "Fortunately we don't have an acute problem right now, but we may have a significant problem in 50 years with groundwater if we keep on doing this."

The use of road salt is no small matter. Snowplow drivers apply nearly 350,000 tons of it in the greater metro area each winter, said Eric Novotny, one of the researchers who tracked movement of the salt using state data.

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