Provisions of the Surface Mining Control and Reclamation Act of 1977 recognized a nationwide need for hydrologic information in mined and potentially mined areas. This report is designed to be useful to mine owners, operators, regulatory authorities, citizens groups, and others by presenting information on existing hydrologic conditions and by identifying additional sources of hydrologic information. General hydrologic information is presented in a brief text accompanied by a map, chart, graph, or other illustration for each of a series of water-resourcesrelated topics. The summation of the topical discussions provides a description of the hydrology of the area. The Eastern Coal Province has been divided into 24 hydrologic study areas which are shown on the cover of this report. The divisions are based on hydrologic factors, location, and size. Hydrologic units (surface drainage basins) or parts of units are combined to form each study area. Study Area 2 covers northwestern Pennsylvania and a small part of southwestern New York. Most exposed bedrock is of Pennsylvanian, Mi;;sissippian, or Devonian ages. Glacial drift covers most of the bedrock in the northwestern part of the area. During 1979, more than 7 million tons of bituminous coal was produced from about 230 mines in Area 2 counties. Over 99 percent of the area's coal production is from surface mining. Streamflow data are available for 18 continuousrecord stations; 1 crest-stage, partial-record station; 1 low-flow, partial-record station; and 65 miscellaneous sites. Water-quality data are available for 78 locations. Streams having the highest median specific conductance, highest median dissolved-solids concentrations, lowest median pH, highest median total-iron concentration, highest median total-manganese concentration, and highest dissolved-sulfate concentrations were found in Clarion County, the leading coal-producing county in the area. Statistics on low flow, mean flow, peak flow, and flow duration for gaging stations can be computed from recorded mean daily flows. Similar statistics can be estimated for ungaged streams by regression and graphical techniques. Five ground-water observation wells are being operated in Area 2. Ground-water levels fluctuate seasonally. Depth to water increases with well depth in upland areas and decreases with well depth in valleys. Well yields in the area range from less than 1 to more than 2,000 gallons per minute. Wells in unconsolidated materials usually have higher yields. Ground-water quality is adequate for most domestic purposes, except locally. Additional water-data information are available through: (1) The National Water Data Exchange, (2) The National Water Data Storage and Retrieva