SPRING CHLORIDE BEHAVIOR IN BUCK CREEK AND THE GREAT MIAMI RIVER, OH

Anthropogenic additions of chloride into rivers are delivered from road salt, sewage treatment, and agricultural runoff. This study focuses on exploring the hydrogeochemical controls of chloride loading during March and April 2013 from a small watershed, Buck Creek (363 km²), and comparing with lon term (1997-2012) trends observed from the larger watershed, the Great Miami River at Miamisburg (6954 km²). Great Miami data were collected, analyzed, and provided by the Heidelberg University National Center for Water Quality Research (NCWQR). The small watershed, Buck Creek, is dominantly agricultural (79%) with little urban area (4%). Similarly, the Great Miami River above Miamisburg is 80% agricultural and 5% urban landuse. Chloride additions were elevated in Buck Creek during March2013 storm events, with high flow concentrations (up to 96 mg/L), almost three times the average (33 mg/L) of all Buck Creek samples at low flow. While the Great Miami River at Miamisburg is more than 10 times the size of Buck Creek, historical average March and April chloride loading was only seven times higher. Interestingly, chloride loading in the Great Miami has significantly increased throughout the 15-year record, and this correlates with increasing March discharge. Here we explore chloride behavior at distinct watershed scales and discuss how climate forecasts for greater spring storms in the Midwest might continue to impact chloride fluxes through time.