The difference between the potentiometric surfaces of the upper Patapsco aquifer, September 1990 and September 1997 in southern Maryland

This report presents a map that shows the change in the potentiometric surface of the Upper Patapsco aquifer in the Upper Patapsco Formation of Cretaceous age in Southern Maryland for September 1990 and September 1997. The map, based on water-level measurements in 38 wells, shows that the change of the potentiometric surface during the 7-year period ranged from zero in the most northern part of the study area, which is near the outcrop of the aquifer, to a decline of 19 feet at LaPlata, which is near the most southwestern part of the study area.