1. Potentiometric surface of the Magothy Aquifer in southern Maryland, September 1991 [microform] Yale Public content 1993. 2002-06-01T04:00:00Z. 2002-06-01T04:00:00Z. Geological Survey (U.S.). U.S. Geological Survey ; Books and Open-file Reports Section. English. Public. Maryland, Southern and Magothy Aquifer.