Road Salt Contamination in Urban and Rural Streams of the Mohawk Valley, NY

Rock salt (sodium chloride) is the main de-icing agent used on roads throughout the northern United States. Road salt usage has increased over time since the 1940\u27s and currently amounts to about 25 million tons being released in the environment annually in the US alone. Much of this salt enters streams directly through runoff, but some also enters through groundwater leading to elevated concentrations year-round. This has caused an observable increase in salt concentration in streams, with higher concentrations observed in areas with higher proportions of impervious surfaces. The major concerns of the increased sodium chloride concentrations are the effect on freshwater ecosystems and roadside vegetation as well as the salinization of groundwater. In this study, the concentrations of sodium and chloride ions in rural and urban streams in and around Schenectady were investigated. The goals of the study were 1) to determine whether Cl- concentrations exceed the recommended USEPA level of 230 mg/L determined to be the threshold level for chronic effects on aquatic life, 2) to determine the effect of urbanization on Na+ and Cl- concentrations in streams, and 3) to monitor seasonal changes of the ions in a single stream (Hans Groot\u27s Kill). Water samples from a total of 50 streams were collected during the summer of 2019. In addition, we also obtained weekly water samples from the Hans Groot\u27s Kill during the summer and throughout the Fall and Winter. Several streams were found to have Cl- concentrations exceeding the USEPA criterion for chronic effects on aquatic life, with one stream showing Cl- concentrations as high as 572 mg/L. Urban streams exhibited higher concentrations of both ions compared to rural streams, confirming the effect of impervious surfaces on salt concentration in streams. Considerable variation in ion concentrations were observed in the Hans Groot\u27s Kill over time. These variations will be discussed in relation to weather conditions and discharge