Map showing the potentiometric surface of the Magothy Aquifer in southern Maryland, September 1979

This map is based on measurements made on a network of 77 observation wells in southern Maryland. Highest levels of the potentiometric surface, 63 to 67 feet above sea level, were measured near the outcrop or subcrop of the aquifer in topographically high areas of Anne Arundel and Prince Georges Counties. The surface slopes to the southeast to about 5 feet above sea level along much of the western shore of the Chesapeake Bay. Four separate, distinct, and extensive cones of depression have developed in the surface around the well fields of the city of Annapolis, Broadneck, town of Waldorf, and Chalk Point. Several square miles of each cone are below sea level and in localized areas at Chalk Point and Waldorf, the surface is 40 to 50 feet below sea level. The network of wells was developed as part of the cooperative program between the U.S. Geological Survey, the Maryland Geological Survey, and the Maryland Energy and Coastal Zone Administration.