Janet Hren 1986 Two samples were collected from each of six wells in a small watershed in Jefferson County, Ohio, in 1984. The watershed was mined and reclamation begun in 1980. Data collected from 1976 through 1982 indicate that ground-water quality was still changing at that time. The purpose of this study was to determine to what extent ground-water quality continued to change 4 years after mining. The upper saturated zone was destroyed by mining and replaced by spoiled material during reclamation. A new saturated zone then formed in the spoils material. The premining median concentrations of sulfate, manganese, and dissolved solids in the upper saturated zone were 84 milligrams per liter (mg/L). 30 micrograms per liter (?g/L), and 335 mg/L, respectively. The postmining median concentrations of these constituents in the upper-zone wells disturbed by mining were 360 mg/L, 595 ?g/L, and 814 mg/L, respectively. Concentrations of these constituents were still increasing in 1984 in the upper saturated zone. In the area not disturbed by mining, concentrations have remained nearly at premining levels. The premining median concentrations of sulfate, manganese, and dissolved solids in the middle saturated zone were 47 mg/L, 10 ?g/L and 405 mg/L, respectively. The postmining median concentrations were 390 mg/L, 490 ?g/L, and 959 mg/L, respectively. In the middle saturated zone, concentrations of these constituents also were still increasing in 1984, probably due to mixing with water if the upper saturated zone. application/pdf 10.3133/wri864108 en U.S. Geological Survey Changes in ground-water quality resulting from surface coal mining of a small watershed in Jefferson County, Ohio reports