In most areas, groundwater in the sand and gravel aquifers is shallow and susceptible to contamination from anthropogenic sources and saltwater intrusion.
Of the approximately 450 million gallons per day of water that enters these lenses as recharge from precipitation, about 69 percent discharges directly to the coast, about 24 percent discharges to streams, and almost 7 percent is withdrawn by public-supply wells. Six hydraulically distinct groundwater-flow systems (lenses) have been delineated on Cape Cod. Groundwater discharged from aquifers also supports freshwater pond and stream ecosystems and coastal wetlands. Groundwater is the sole source of drinking water and a major source of freshwater for domestic, industrial, and agricultural uses on Cape Cod, Massachusetts.
