GEOCHEMICAL AND SEDIMENT ANALYSIS OF UPPER HEMLOCK CREEK, COLUMBIA COUNTY, PA

Hemlock Creek lies in central Columbia County, PA, and has been previously affected by erosion problems and agricultural runoff. The purpose of this research is to quantify the amount of sediment present in the Hemlock Creek, and to determine the contribution of metals from natural or anthropogenic sources. Water samples were analyzed for pH, conductivity, and dissolved oxygen in-situ and for total alkalinity and acidity in the lab. Water quality analysis performed includes using a Leeman Profile ICP-OES to analyze metal concentrations, as well as a Dionex ICS-2000 Ion Chromatograph to measure cations and anions in each sample. Since sediment was the primary focus, a HACH Turbidimeter was used to quantify sediment. Samples were preserved at 4°C until analyzed. Water samples were analyzed for Al, As, Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn by ICP OES. Of these metals, only Al, Ba, Fe, Mn, Ni, and Cu were detected, and none at levels of concern. Of the major anions analyzed using ion chromatography, only nitrate was detected. The pH of the stream ranged from 7.2 to 7.8, well within the PA chapter 93 criteria of pH 6 to 9 for cold water fishes, and the dissolved oxygen in the stream averaged around 10 mg/L. Water quality criteria state that a minimum DO of 5 mg/L is required for fish. Our analysis indicates overall water quality in Hemlock Creek remains suitable for aquatic life, although turbidity was above the TMDL of 1 NTU in all samples. Elevated turbidity may be due to the predominantly agricultural land use in the upper half of the watershed. This research is important to maintaining stream health and establishing baseline levels for future studies.