ASSESSING THE IMPACTS OF URBAN ROAD SALTING ON TRIBUTARIES OF THE CHIPPEWA RIVER NEAR EAU CLAIRE, WISCONSIN

Road salting is a necessary means of improving road conditions in cold weather regions with frequent winter precipitation. In Wisconsin, over 1 billion pounds of salt are applied to roadways during each winter season. This salt can enter local streams during periods of increased runoff and can negatively impact aquatic ecosystems. To assess how road salting is impacting waterways near Eau Claire, Wisconsin, electrical conductivity measurements and water samples were collected from five streams during the 2012 winter season. The streams were chosen due to their proximity to urban areas; three of the stream sites are located near bridges along Eau Claire urban roadways. During the 2013 winter season, four new monitoring stations were added. Two of the new locations are upstream from previously established sites, in areas with less urban development. The other sites are on the two rivers, the Chippewa and the Eau Claire, that flow through the city of Eau Claire.

Data from the 2012 monitoring season showed that there is an excellent correlation between electrical conductivity measurements and chloride concentrations. Therefore conductivity measurements can be used as a reliable proxy for determining actual chloride levels in local streams. Conductivity measurements increased during snowfall events and decreased during warmer periods, showing that road salt is affecting chloride concentrations in these streams. The 2012 monitoring period was unusually warm and had little snowfall, and the conductivity values were generally less than the EPA established value for surface water degradation due to road salting. The 2013 season has had more typical precipitation, and higher conductivity values were observed. The sampling sites added in 2013 have shown that chloride concentration is influenced by adjacent development, as more rural upstream sites show lower concentrations than downstream urban sites.