The hydrogeology of the 75-square mile Clifton Park suburban area near Albany, N.Y., is presented in six maps at 1:24,000 scale. The maps show: (1) location of wells and test holes; (2) bedrock topography; (3) surficial geology and geologic sections; (4) saturated thickness of the confined aquifer; (5) generalized soil permeability; and (6) land use. The aquifers in the Clifton Park area serve approximately 22,000 people through 32 public distribution systems. Average daily pumpage from these systems is approximately 1.85 million gallons per day. The most productive aquifer is the Colonie Channel aquifer, a confined, buried bedrock channel aquifer of glacial material from which wells may yield more than 500 gallons per minute. A water-table aquifer of fine sand is present over most of the area and is separated from the confined aquifer by a thick sequence of lacustrine silt and clay. Recharge to the confined aquifer occurs primarily where kame-delta deposits that are exposed at land surface are hydraulically connected to the buried aquifer. Saturated thickness of the confined aquifer varies from less than 5 feet to approximately 70 feet. In recharge areas, where the aquifer is locally under water-table conditions, saturated thickness may exceed 100 feet. Pumping interference between wells tapping the confined aquifer has been observed over distances of 3/4 mile. (USGS)