Map showing how the potentiometric surface of the Magothy Aquifer of September 1979 differed from the potentiometric surface of September 1977 in southern Maryland

This map is based on the differences between two sets of water-level measurements made in 63 observation wells. One set was made in 1977, a relatively dry year, and the other set was made in 1979, a relatively wet year. The map shows that the potentiometric surface in 1979, in northern Prince Georges County and southern Anne Arundel County, was higher than it was in 1977, with a maximum measured rise of 9 feet. In southern parts of the mapped area, the 1979 potentiometric surface was lower than the 1977 surface, with a maximum measured decline of 11 feet. The network of observation wells was developed and is operated and maintained as part of the cooperative program between the U.S. Geological Survey and agencies of the Maryland Department of Natural Resources. (USGS)