Potentiometric surface of the Aquia Aquifer in southern Maryland, September 1991

A map showing the potentiometric surface of the Aquia aquifer in the Aquia Formation of Paleocene age in southern Maryland during September 1991 was prepared from water levels measured in 82 wells. The potentiometric surface was above sea level near the northwestern boundary and outcrop area of the aquifer in topographically high areas of Anne Arundel and Prince Georges Counties, and was below sea level in the remainder of the study area. The hydraulic gradient was directed southeastward toward an extensive cone of depression around well fields at Lexington Park and Solomons Island. Groundwater levels were more than 60 feet below sea level in a 60-sq-mi area surrounding the deepest part of the cone of depression and 117 feet below sea level in one well near the center of the cone.