Roadside snowmelt: a management target to reduce lake and river contamination

Abstract

ABSTRACT Major ion concentrations have greatly increased in many north temperate lakes and rivers over the last 3 decades as the result of deicing materials applied to their surrounding roads in winter. Salt-based deicing will likely continue or increase in the future, and preventative management strategies require an improved understanding of the flow pathways and timing of road salt and associated contaminant fluxes to downstream receiving waters. In the present study, we focused on the catchment of Saint-Charles River and its reservoir that provides drinking water for Quebec City, Canada. Major ion concentrations were measured in river waters and snowbanks along roads in subcatchments that differed in degree of urbanization, and during the same winter–spring period a mooring system was installed in the reservoir to continuously record conductivity. Large significant differences were found in the concentration and temporal behavior of ions between urbanized and forested watersheds. Snow sampled at 1 m from the roads had elevated concentrations of salts and other contaminants, and the highest solute concentrations in the reservoir and river waters occurred during snowmelt events. The results indicate that management of roadside snowmelt runoff during thawing events may largely prevent salt-associated contamination, and that winter snowmelt will require increasing attention as the climate continues to warm.