DIFFERENTIATING BASIN BRINE AND ROAD SALT FINGERPRINTS IN HEADWATER STREAMS ON THE NY/PA BORDER

Four adjacent headwater watersheds, the Wappasening, Apalachin, Choconut and Snake Creek watersheds, located along the NY/PA border, were selected from the Susquehanna River Basin Commission’s (SRBC) Remote Water Quality Monitoring Network for a geochemical assessment of stream water sources. The SRBC operates a real-time network of sondes that measure stage, temperature, specific conductivity, pH, turbidity and D.O. Upstream from the SRBC sondes, six additional sondes that measure stage, temperature and conductivity, were used to differentiate upstream (watershed area of 20-60km²) and downstream (watershed area of 100-140km²) relationships. In conjunction with other sonde parameters, conductivity is commonly used as a proxy to assess changes in water sources, however such an approach can not be used to differentiate basin brine and road salt source impacts.

To better assess water sources from a geochemical perspective, grab samples were collected from the ten sonde locations in 2012 during the Spring (every 2 weeks), and Summer and Fall (every 7-10 days), accompanied by discharge and rainfall measurements. The grab samples were analyzed for major and minor cation (ICP-OES) and anion (IC) concentrations. Sonde measured stream conductivity trends were coupled with cation and anion fingerprints to differentiate road salt from basin brine sources. Groundwater collected from individual homeowners in rural communities located in the watersheds of interest was compared to the stream water geochemical fingerprint to aid in identification of the road salt and basin brine impacts. In addition, sample collection from Salt Springs State Park, PA was used as means to demonstrate how a basin brine source discharging at the surface, that mixes with other stream water sources, can be identified from sonde measurements under changing hydrological conditions.