The Beaver River Basin is studied as part of the Ohio River pollution survey. The streams and reservoirs of the basin are intensively used as sources of municipal and industrial water supplies and for recreation. Except for the Beaver and sections of the Mahoning and Shenengo Rivers, the streams of the basin are relatively clean. Reservoir sites have been investigated with a view toward providing needed additional flow for both pollution abatement and industrial water supply. Eighteen of the 50 public water supplies in the basin are from surface sources. Primary treatment is indicated at four other communities where stream flows are adequate. Improvements are needed at eight facilities. Industrial treatment is needed primarily to reduce phenol discharges and the acid load on the stream.