Geologic and Geohydrologic Reconnaissance of Staten Island, New York

Soren, Julian

Staten Island (Richmond County) is a mainly suburban borough of the City of New York in which considerable interest in ground water has grown as a result of protracted droughts that seriously reduced the City’s water supply from its upstate surface-reservoir system in the 1960’s and 1980’s. Hundreds of residents and business installed wells, mainly for lawn and plant-nursery irrigation, filling swimming pools, and vehicle washing, because the City prohibited use of the public-water supply for such purposes during the droughts. Fresh ground water is available from Upper Proterozoic to Lower Jurassic bedrock and from overlying unconsolidated sandy Upper Cretaceous and upper Pleistocene deposits. The principal source of fresh ground-water recharge is precipitation that infiltrates the land surface and percolates to the water table. Fresh ground water moves downward and laterally through the unconsolidated deposits and bedrock toward discharge points--streams and tidewater that surround the island and saline ground-water that underlies it at depth. Four maps of Staten Island’s geology and water-table levels provide information on ground-water availability and serve as a basis for future ground-water investigations. Streamflow on Staten Island has not been noticeably reduced by current ground-water development, which indicates that the ground-water reservoir has not been significantly depleted and that considerably more ground water is available for use.