This winter's heavy snowfall has required record amounts of salt to be scattered over Wisconsin roads. Water quality experts are now raising concerns regarding the potential environmental effects of these higher-than-usual salt levels.
A U.S. Geological Survey scientist discovered in 2008 that seven of 12 streams in metropolitan Milwaukee exhibited acute toxicity on fathead minnows and a type of water flea following two significant rain events. Chloride concentrations exceeded the U.S. Environmental Protection Agency's toxic standard of 850 parts per million (ppm) on the Kinnickinnic, Menomonee and Root rivers and Honey, Underwood, Lincoln and Little Menomonee creeks, according to scientist Steve Corsi.
Corsi measured chloride levels in Honey Creek at 6,470 ppm in February 2007; the creek water was essentially saline for a few hours. The Parnell Creek in Kettle Moraine State Forest, however, registered 20.4 ppm; this control stream was not affected by road salt.
"A significant number of streams are highly impacted by road salt," Corsi said, noting the first melt after a storm brings the most significant damage.
According to state Department of Transportation estimates, 700,000 tons of salt will be used on Wisconsin highways this year; the state used 405,000 tons last winter.
"This is really a dilemma because we want to keep our roads safe," said Roger Bannerman, a water resources management specialist with the Wisconsin Department of Natural Resources. "But the problem is real, and it's going to be growing worse over time."
Source: Milwaukee Journal Sentinel
