Geographic information system data sets of hydrogeologic conditions in Pequea and Mill Creek watersheds, Pennsylvania: Part I — Basic data

This report describes basic data used to develop Geographic Information System data sets of bedrock geology, sinkholes and closed depressions, and spring and well locations attributed with hydro- geologic and water-quality data in the Pequea and Mill Creek watersheds, a 210-square-mile area in Lancaster and Chester Counties, Pa. The data sets, which do not contain hydrogeologic interpretations, were developed by the use of ARC/INFO software during 1990-93 by the U.S. Geological Survey, in cooperation with the Pennsylvania Department of Environmental Resources. The U.S. Environmental Protection Agency proposes to use these noninter- pretive and interpretive data sets, and those from other sources, to aid in the assessment of ground- water vulnerability to pesticides in the Pequea and Mill Creek watersheds.