The National Water-Quality Assessment Program assesses ground water and streams in the Hudson River Basin in eastern New York, in the headwaters of the Delaware River Basin and on Long Island in the southeast, and in a small part of the Lake Erie-Saint Clair Drainage in the southwest. Among the issues addressed by the Program are the release of PCBs to river water and its accumulation in bottom sediments and fish tissue; degradation of stream and ground-water quality by urban and agricultural sources of fertilizers and pesticides; condition of biological communities as a result of habitat disturbance and water-quality degradation; and transport of pollutants entering sensitive estuaries in the New York Harbor.