Road Salt Loading in the Fall Creek Watershed

Abstract

This project models the rising chloride concentrations in the Fall Creek watershed located near Ithaca, New York. Base-line salinization levels for freshwater in the northeastern United States have been increasing over the past several year and road salt has been identified as a possible primary source (Kaushal et al., 2005). Investigation is required to determine what detriment this may be causing to freshwater sources and environments. Data shows current concentrations in Fall Creek watershed to be 18.8 ppm as of 2003 (Bouldin, unpublished). By modeling Fall Creek watershed as a continuously stirred tank reactor (CSTR), it is possible to predict the increasing trends in salt concentrations in the watershed matching the data that was previously collected beginning in the 1970s. Based on data collected regarding quantities of salt purchased by local municipalities surrounding the watershed and inputs from wet atmospheric deposition, the model shows that the watershed system will reach steady state in approximately the year 2550 at a concentration of 35.4 ppm. Based on current conditions the salt concentration in the watershed could reach 30 ppm over the next hundred years. Harmful salt concentrations can range anywhere from 30 to 250 ppm as a conservative estimate, although accurate information in this area seems difficult to obtain. Though current concentrations in the watershed are below this range, continued monitoring of the area is important in order to supply data that could be used to make informed decisions regarding local salt spreading policies and management techniques.