The U.S. Geological Survey in cooperation with the New York State Department of Environmental Conservation, the Tug Hill Commission, the Jefferson County Soil and Water Conservation District, the Oswego County Soil and Water Conservation District, and the Tug Hill Land Trust studied the northern and central parts of the Tug Hill glacial aquifer to better understand and explain the dynamics of the aquifer to help communities make sound policy decisions about groundwater use. This dataset includes aquifer boundaries, discharge and water quality sites, geologic sections, records of selected wells, surface water temperature sites, generalized surficial geology, and water level contours for the northern and central parts of the Tug Hill aquifer. The southern part of the aquifer was beyond the scope of the study.