GEOCHEMICAL STUDY OF OULEOUT CREEK, NY
Water samples were collected in triplicates at six sites during fall and spring in the Ouleout Creek watershed. At each site, field parameters such as dissolved oxygen, electrical conductivity, total dissolved solids, pH, temperature, and turbidity were recorded. Dissolved silica content was determined using a colorimetric method and a spectrophotometer. The water samples were filtered and preserved using concentrated nitric acid to lower the pH below 2 or by freezing. The samples were analyzed for cation and anion compositions with atomic absorption spectroscopy and ion chromatography, respectively.
The chemical composition of the water reflects the geology of the watershed with calcium and sodium as the dominate cations, and chloride and sulfate as the dominate anions. No significant inorganic contaminations are found. Higher chloride and sodium concentrations in the spring samples indicate road salt input by snowmelt runoff. Total dissolved solids values do not vary among sites and are only slightly elevated in the spring samples. The dam does not seem to affect the chemical composition of the water. Turbidity is higher below the dam, which is consistent with the operation of a bottom release dam. Overall, the stream is clean and only the suspended sediment load downstream is affected by the dam. Future investigations of storm events on nutrient and sediment loads are needed to better understand the effect of the dam on water quality downstream.