WINTER CHLORIDE BEHAVIOR IN OHIO RIVERS AND THE INFLUENCE OF LAND USE AND CLIMATE

Studies suggest that an increase in salinity of a waterway can harm the habitat and the organisms living in that habitat. Chloride concentrations at or above 250 mg/L are toxic to organisms. Sources of chloride to watersheds include fertilizer, sewage, and road salt. Chloride levels in urban areas are increasing, especially during the winter months. This study compares the average chloride concentration over a week in February of 2016 of the Mad River, in Springfield, Ohio, to the average chloride concentration for the winter of 2015 of the Scioto River, Muskingum River, Honey Creek, and the Great Miami River using 8 hour sampling data from the National Center for Water Quality Research at Heidelberg University, in Tiffin, Ohio. Mad River samples were collected from February 23, 2016 to March 2, 2016. The February 2016 samples from the Mad River contained less average chloride (25.3 mg/L) than all other samples in spite of having the most urban land use (9.0%). The Scioto, which has a 4.6% urban land use, had the highest average winter chloride concentration of 111.1 mg/L. There was no general relation between watershed specific discharge and chloride yield. The study was further expanded to include the analysis of chloride concentration and flow over a longer period (1996-2015). Flow generally increases through time for all sites. Honey Creek and the Great Miami River exhibit a larger increase in specific discharge over time. There is a general increase in chloride concentration over time for the Scioto River, but no trend for other sites. Chloride yields exhibited a slight decrease through time. Fewer snow events may have led to a decrease in road salt applications and associated runoff. This work suggests that while land use largely explains differences between comparisons made over the same time period, variation between years may reflect changing deliveries associated with climate conditions. Excess chloride can harm habitats and contaminate the ground water supply that humans depend on, and therefore more work should evaluate the interplay between land use, climate, and chloride response.