Cape Cod Aquifer, Cape Cod, Massachusetts

Abstract

Ground water was the major source of drinking water on Cape Cod, Massachusetts in 1978. Withdrawals from over 100 municipal wells averaged 17.5 million gallons per day in 1978. Private wells on Cape Cod are estimated to number 15,000. Ground water occurs primarily under unconfined or water-table conditions. Artesian conditions exist where fine silt and clay beds have been deposited along Cape Cod's north shore from Bourne to Brewster, locally along the south shore, and in parts of Chatham and Orleans. Natural recharge to the aquifer is entirely from precipitation. Discharge is by pumping; evapotranspiration; direct evaporation from the water table; and seepage to rivers, marshes, and the ocean. Ground-water quality is generally suitable for domestic uses, although some public and private water wells have been contaminated. Contaminants can enter the ground water by infiltration from land surface, ponds, streams, and swamps. Infiltration from sewage lagoons, sand filter beds, septic tanks, cesspools, recharge pits, wells, or intrusion of saline water may also contaminate the aquifer. Alternative sources of drinking water, including desalination, transport from the mainland, and rainwater cisterns, are many times more expensive.