Regional analysis of the effect of paved roads on sodium and chloride in lakes

Water Research, 46:2749-2758

Daniel Kelting, Corey Laxson, Elizabeth Yerger

Salinization of surface water from sodium chloride (road salt) applied to paved roads isa widely recognized environmental concern in the northern hemisphere, yet practicalinformation to improve winter road management to reduce the environmental impacts ofthis deicer is lacking. The purpose of our study was to provide such information bydeveloping baseline concentrations for sodium and chloride for lakes in watershedswithout paved roads, and then determining the relationship between these ions anddensity, type, and proximity of paved roads to shoreline. We used average summer(JuneeSeptember) sodium and chloride data for 138 lakes combined in a watershed basedanalysis of paved road networks in the Adirondack Park of New York, U.S.A. The water-sheds used in our study represented a broad range in paved road density and type, 56 ofwhich had no paved roads. Median lake sodium and chloride concentrations in these 56watersheds averaged 0.55 and 0.24 mg/L, respectively. In contrast, the median sodium andchloride concentrations for the 82 lakes in watersheds with paved roads were 3.60 and7.22 mg/L, respectively. Paved road density (lane-km/km2) was positively correlated withsodium and chloride concentrations, but only state roads were significantly correlated withsodium and chloride while local roads were not. State road density alone explained 84percent of the variation in both ions. We also successfully modeled the relationshipbetween road proximity to shoreline and sodium and chloride concentrations in lakes,which allowed us to identify sections of road that contributed more to explaining thevariation in sodium and chloride in lakes. This model and our approach could be used aspart of larger efforts to identify environmentally sensitive areas where alternative winterroad management treatments should be applied.