HOW MUCH MORE CAN WE TAKE? - ROAD SALT AS AN EMERGING CONTAMINANT IN STREAMS

Increasing chloride concentrations in surface waters has become a new and widespread threat to drinking water supplies and ecosystem functions in recent years. Many studies have reported chloride concentrations approaching or exceeding drinking water standards and impacted aquatic stream habitats such as freshwater mussel species in northeastern United States and Ontario, Canada due to road salt application. A simple integrated catchment model for chloride has been developed to assess the transport of road salt from upland areas in watersheds to streams using readily accessible landscape, hydrologic, and meteorological data together with reported salt applications. Fishkill Creek, located in Southern New York, is a suburbanizing watershed with main land uses of urban and forest. It typifies many watersheds in the northern snowbelt region with intensive road salt application in the winter. We applied the model to Fishkill Creek as a representative watershed to test the model. Specific conductivity measured in the field using a water quality probe proved to be useful in predicting chloride concentrations in streams. Modeling results showed good agreement between modeled and measured flow and stream water chloride concentrations. Scenario analysis of increase and decrease in salt applications suggests the retention of road salt in soils and groundwater as well as the importance of long term management of salt application to reduce contamination in streams.