EXPLORING WINTER CHLORIDE EXPORT IN WATERSHEDS WITH URBAN AND MONTANE-FORESTED TRANSPORTATION NETWORKS AND DISTINCT WINTER CLIMATES USING DISTRIBUTED CONDUCTIVITY SENSORS

Elevated chloride concentrations due to de-icing salt application is threatening regional water quality by increasing the salinity of streams and their receiving waters across the northeastern U.S. The region is also experiencing warmer winters that are more hydrologically active, increasing the frequency of runoff events that can initiate road salt transport into streams. Winter weather whiplash—a phenomenon characterized by fluctuations between cold, snow-dominated conditions where salt application would be prevalent, and warm, rain-dominated systems that promote rapid and sometimes extreme runoff response — can be particularly detrimental to water quality. However, winter water quality monitoring programs designed to observe these effects are limited to nonexistent. Therefore, we have deployed a distributed conductivity sensor monitoring program in four watersheds of the Lake Champlain Basin with varying elevations and dominant land covers. Two focal watersheds are located in the urban environment of Burlington, Vermont, with a low elevation winter climate and snowpack. The other two focal watersheds are mostly forested with a montane winter climate and snowpack but contain the dominant transportation networks that provide access to two of Vermont’s largest ski areas. High-frequency conductivity sensors along with water grab samples will be used to create chloride-conductivity regression equations for each watershed so that chloride concentration can be estimated as a function of conductivity readings. Concomitant gage infrastructure will be used to quantify chloride fluxes at the watershed scale. Results from this work will provide insight into distinct chloride concentration-discharge patterns during winter melt events and compare event and seasonal export patterns between focal watersheds where snowfall dynamics and salt application practices differ.