From purpose and scope: This report provides basic information on the ground-water resources of Chester County, Pennsylvania, which is an area of about 760 square miles (1970 meters) in southeastern Pennsylvania. It discusses the availability and quality of the water in the water-bearing units in the county and the relation of the ground water to surface water.

The model discussed in this report simulates recharge to, flow through, and discharge from the water-table aquifer representative of most of Chester County, Pennsylvania. It includes maps and graphs.

Abstract: Eighty-five stream sites in and near the six-county Greater Pittsburgh Region were sampled in mid-June 1971 and again in mid-October 1972. Concentrations of inorganic nitrogen, organic carbon, or phosphorus were high enough to indicate potential problems at about a quarter of the sampling sites. Temperature, dissolved oxygen, and pH values indicated a generally favorable capacity for recovery from degradation, although a number of streams east of the Allegheny and Monongahela Rivers are marginal or lacking. Regionally, sulfate is the dominant ion and was observed in concentrations of 40 milligrams per liter or more at 90 percent of the sites. Bicarbonate exceeded 100 milligrams per liter at 22 sites. A moderate to high degree of mineralization is indicated by conductance readings of more than 500 micromhos per centimeter at half of the sampling sites.

Purpose: This investigation by the U.S. Geological Survey, in cooperation with the Warminster Municipal Authority, has three purposes: (1) to determine how urbanization has affected ground water and low streamflow in Warminster Township and parts of the surrounding municipalities; (2) to describe the hydrologic system; and (3) to assess the availability of ground water.