Reports
Geology and water resources of Prince George's County
1952, Cooke, C.W., Martin, R.O.R., and Meyer, G.
Bulletin 10
Abstract
Prince Georges County is in the south-central part of Maryland near the western shore of Chesapeake Bay. The county is almost entirely within the Coastal Plain province; pre-Cambrian crystalline rocks which characterize the Piedmont Plateau are exposed only in some stream valleys near the northwestern edge of the county. The geologic formations of the Coastal Plain in Prince Georges County are of Early and Late Cretaceous, Paleocene, Eocene, Miocene, Pliocene (?), and Pleistocene age and consist chiefly of unconsolidated sand, gravel, and clay. Excepting the Pliocene (?) and Pleistocene deposits, which form a thin cover over the older formations, the Coastal Plain formations strike northeast and dip gently to the southeast. Ground water occurs under water-table conditions in and near the outcrops of the formations and under artesian conditions down dip from the outcrops.
During 1949 and 1950 approximately 4,000,000 to 5,000,000 gallons of ground water a day was pumped from wells in Prince Georges County; about 65 percent of this pumpage was used for domestic, agricultural, and public supplies and about 35 percent of this pumpage was used for domestic, agricultural, and public supplies and about 35 percent for industrial and other commercial purposes. The important water-bearing formations are the Patuxent, Patapsco, and Magothy formations, the Aquia greensand, and the Pliocene (?) and Pleistocene deposits.
The Patuxent formation generally yields about 10 gallons a minute to domestic wells, but a few public-supply and industrial wells yield as much as 250 to 540 gallons a minute. The total pumpage from this formation is approximately 1,000,000 gallons a day. Most wells ending in the Patapsco formation yield between 10 and 60 gallons a minute, but one well at Fort Washington is reported to yield 137 gallons a minute. The total pumpage from this formation is approximately 1,000,000 gallons a day. Wells ending in the Magothy formation generally yield 20 to 50 gallons a minute, but a well near Cheltenham is reported to yield 239 gallons a minute and a public-supply well at Upper Marlboro, 180 gallons a minute. Approximately 700,000 gallons of water a day is pumped from the Magothy formation. Yields of wells ending in the Aquia greensand range from 6 to 65 gallons a minute. The total pumpage from this formation is approximately 100,000 gallons a day. The Pliocene (?) and Pleistocene deposits are the chief source of water for domestic and farm use. Although the largest yield reported from wells ending in these deposits is only 12 gallons a minute, the total pumpage is approximately 1,300,000 gallons a day.
Old records of water-level measurements compared to recent measurements indicate that pumping has caused the piezometric surfaces to decline locally since the early part of the twentieth century, but in general periodic measurements made in observation wells show little net change in water levels during 1948-50.
The chemical character of the ground water is satisfactory for most uses, but in some places the water is acidic or contains a large amount of iron.
