Altitude and configuration of the potentiometric surface in the crystalline and metasedimentary rocks in Valley and West Brandywine townships, Chester County, Pennsylvania, May 1992 through August 1993

A map showing ground-water levels in crystalline and metasedimentary rocks in Valley and West Brandywine Townships, Chester County, Pennsylvania, was constructed from water levels measured in wells from May 1992 through August 1993. Pre-1992 measurements were incorporated on the map to provide control in areas where more recent data were not available. Because little ground-water development has occurred in the areas where pre-1992 water levels were used, levels are assumed to be the same in 1992 and 1993 as they were when the measurement was made.