The Mid-Atlantic Region covers a total area of about 108,000 square miles. It includes parts of Vermont, Massachusetts, New York, Pennsylvania, Maryland, West Virginia, and Virginia, the entire States of New Jersey and Delaware, and the District of Columbia. It encompasses the entire drainage basins (within the United States) of the Hudson, Delaware, Susquehanna, Potomac, and the James River and includes Long Island and the coastal drainage of New Jersey, Delaware, Maryland, and Virginia.
Ground water in the region occurs in three broad types of geologic terrane: (1) unconsolidated deposits in the Coastal Plain seaward of the Fall Line; (2) hard, consolidated sedimentary rocks and crystalline igneous and metamorphic rocks in the remainder of the region; and (3) unconsolidated sand, gravel, and other deposits of glacial origin that overlie the older rocks extensively in the glaciated northern part of the region.
Ground water is derived primarily from precipitation; it can be intercepted for use by pumping from wells before it reaches the streams or before it drains into coastal wetlands or the ocean.
The natural discharge from the aquifers in the region is estimated to be at about 38.6 billion gallons per day; in addition, at least 140-350 trillion gallons is stored in the rocks.
About 949 billion gallons of fresh ground water was withdrawn in 1970. This quantity represents about 9 percent of the total freshwater use of 10,220 billion gallons. Available ground-water reserves indicate that a considerable part of the additional supplies needed for the anticipated increase in economic activity in the region could be developed from ground water.
