Geohydrology of the valley-fill aquifer in the Sprout and Fishkill creeks area, Dutchess County, New York

This report is the fifth in a series of 11 map sets depicting geohydrologic conditions in selected aquifers in upstate New York. Geohydrologic data are compiled on six maps at 1:24,000 scale. Together the maps provide a comprehensive overview of a major valley-fill aquifer in southwestern Dutchess County and a small part of Putnan County. The maps include surficial geology, geologic sections, water-infiltration potential of soil zone, aquifer thickness, water-table elevations and land use. The valley-fill deposits consist of alluvial silt and sand, glacial-outwash (sand and gravel), ice-contact sand and gravel, till, and lacustrine silt and clay. The sand and gravel have relatively high permeabilities whereas the till, silt and clay deposits have relatively low permeabilities. Saturated layers of sand and gravel underlie confining layers of silt and clay, and also underlie confining till. The water-infiltration potential of the soil zone of the valley-fill varies widely. Aquifer thickness data is sparse, especially data on the lower confined aquifer layers. Water-table elevations within the surface aquifer are gently sloping, directing ground-water flow towards streams into which discharge occurs. The use of land overlying the aquifer is predominantly agricultural and residential, with lesser amounts of commercial and industrial uses. (USGS)