Geohydrology of the Lloyd aquifer, Long Island, New York

Abstract

The Lloyd aquifer contains only about 9 percent of the water stored in Long Island's groundwater system but is the only source of potable water for several communities near the north and south shores. The Lloyd aquifer is virtually untapped throughout most of central Long Island because current legal restrictions permit its use only in coastal areas. The upper surface of the Lloyd aquifer ranges in depth from 100 feet below land surface on the north shore to more than 1,500 feet on the south shore. Aquifer thickness increases southward from 50 feet to about 500 feet. Transmissivity ranges from 1,500 to 19,000 feet squared per day. All recharge (35 to 40 million gallons per day) and nearly all discharge is through the overlying confining unit. Nearly all of the pumpage (approximately 20 million gallons per day) is in Queens and along the north and south shores of Nassau County.