Geohydrology of the Bethpage-Hicksville-Levittown area, Long Island, New York

A study of ground-water levels and flow in east-central Nassau County, N.Y. , began in October 1985. The 11.4 sqare-mile area encompasses parts of Bethpage, Hicksville, Levittown, Plainview, Plainedge, and Farmingdale.

Approximately 1,200 ft of unconsolidated Cretaceous deposits and 50 to 100 ft of Pleistocene deposits overlie bedrock throughout the area. The unconsolidated deposits consist mostly of sand, gravel, silt, and clay and have good water-transmitting properties except where clay forms continuous layers that can impede groundwater flow.

The area is mostly residential and industrial. Pumpage for public supply exceeds 10 million gallons per day, most of which eventually discharges from the ground-water system to tidewater as sewage outflow. Industrial pumpage during summer exceeds 10 million gallons per day, but most of the water is returned to the system through recharge basins. Ground-water levels in this area fluctuate seasonally in response to natural recharge, pumping, and use of recharge basins.