Problem - Several supply wells in Oswego County were evaluated by the USGS in 1999 by using stable oxygen and hydrogen isotopes and chlorofluorocarbon (CFC) age dating techniques. For two municipal well sites (the Villages of Sandy Creek and Lacona, and the Village of Pulaski) that tap a shallow, unconfined aquifer (typically 20-50 ft thick) there were significant discrepancies between ground-water recharge ages determined by chemical data and those determined by ground-water-flow models developed by independent studies.
The significant discrepancies between the times of travel of ground water as determined by numerical ground-water-flow modeling and geochemical dating techniques in Oswego County need to be understood and a coherent conceptual model of the ground-water flow system developed before water managers and government agencies can implement effective ground-water protection strategies.
Objectives - Refine the understanding of the ground-water flow system in a shallow, sand-and-gravel aquifer in Oswego County. Reconcile differences in recharge ages and ground-water-flow rates estimated by numerical ground-water-flow modeling and geochemical techniques for one of the sites (Sandy Creek-Lacona municipal well) that taps the Tug Hill aquifer. Determine whether there are significant vertical flow components within the sand and gravel aquifer and (or) whether there are sources of older water, such as bedrock, that discharge into the sand-and-gravel aquifer. The new data collected in this study will be used to revise the ground-water-flow model of the area previously built by the USGS.
Approach - The study is divided into two phases. Phase I included test drilling and water sampling for age determination. Phase II, entailed the revision of the USGS ground-water-flow model of the sand-and gravel-aquifer, which is tapped by the Sandy Creek/Lacona municipal wells. The revision included converting the existing two-dimensional model to a three-dimensional model.
Benefits - The understanding of the ground-water flow system and travel times gained from this study may be applied to other supply wells in Oswego County where hydraulic and geochemical approaches have yielded disparate results. This study will provide valuable data to local, state, and federal agencies that are responsible for developing source water delineations and protection strategies for public water supplies.
Related Publications - Miller, T.S., Bugliosi, E.F., Hetcher-Aguila, K.K., Eckhardt, D.A., 2007, Hydrogeology of two areas of the Tug Hill glacial-drift aquifer, Oswego County, New York: U.S. Geological Survey Scientific Investigations Report 2007–5169, 42 p, online only.