1. Potentiometric surface of the upper Patapsco Aquifer in southern Maryland, September 1994 [microform] Yale Public content 1995. 2002-06-01T04:00:00Z. 2002-06-01T04:00:00Z. Geological Survey (U.S.). U.S. Geological Survey ; Books and Open-file Reports Section, [distributor. English. Public. Maryland, Southern and Patapsco Aquifer.