ANALYZING SOFT SEDIMENT CORES TO DECIPHER POST-DAM ACCUMULATION HISTORY IN KELLER RESERVOIR, CLINTON COUNTY, PENNSYLVANIA

The Keller Reservoir in Clinton County, PA, serves as the source of drinking water supply for 19,500 subscribers. The reservoir is located within the McElhattan Creek Watershed and drains 18 mi² area. The dam was originally constructed in 1956 and is fed by two contributing streams, namely McElhattan Creek and East Kammerdiner Run. These creeks carry a substantial amount of sediments that eventually deposit in the reservoir. Sediment accumulation poses a problem by decreasing water storage in human-made reservoirs and by increasing cost to the water filtration plant. A ground penetrating radar (GPR) survey revealed the bathymetry and sediment-bedrock interface in the reservoir; however, determination of the thickness of sediments accumulated since the construction of the dam posed a challenge. Additionally, an ArcSWAT model for the watershed was developed to determine sediment yield and accumulation patterns within the study area. Undisturbed sediment cores were collected from different locations within Keller Reservoir to verify the results of the ArcSWAT model in the field. These cores helped reveal the thickness of sediments accumulated since the inception of the dam; while x-ray fluorescence (XRF) analysis helped determine the origin of these sediments.