A subsurface clay dike and mine-entrance hydraulic seals were constructed from July 1979 through May 1980 by the Ohio Department if Natural Resources, Division of Reclamation to reduce acidic mine drainage from abandoned drift-mine complex 88 into Big Four Hollow Creek. Big Four Hollow Creek flows into Sandy Run--the major tributary to Lake Hope. A data-collection program was established in 1979 by the U.S. Geological Survey to evaluate effects of drift-mine sealing on surface-water systems of the Big Four Hollow Creek and Sandy Run area just below the mine. Data collected by private consultants from 1970 through 1971 near the mouth of Big Four Hollow Creek (U.S. Geological Survey station 03201700) show that pH ranged from 2.7 to 4.8, with a median of 3.1. The calculated iron load was 50 pounds per day. Data collecetd near the mouth of Big Four Hollow Creek (station 03201700) from 1971 through 1979 (before dike construction) show the daily pH ranged from 2.1 to 6.7; the median was 3.6. The daily specific conduction ranged from 72 to 3,500 microsiements per centimeter at 25? Celsius and averaged 770. The estimated loads of chemical constituents were: Sulfate, 1,100 pounds per day: iron, 54 pounds per day: and manganese, 12 pounds per day. All postconstruction data collected at station 03201700 through the end of the project, May 1980 through June 30, 1983, show that the daily pH ranged from 2.4 to 7.7, with a median of 3.7. Daily specific conductance ranged from 87 to 3,200 microsiemens per centimeter and averaged 1,200. The estimated loads of chemical constituents for this period were: Sulfate, 1,000 pounds per day: iron, 44 pounds per day: and manganese, 16 pounds per day. Standard nonparametric statistical tests were performed on the data collected before and after reclamation. Differences at the 95-percent confidence level were found in the before- and after-reclamation data sets for specific conductance, aluminum, and manganese at station 03201700. Data collected during the first 6 months after reclamation indicated moderate improvement in water quality only because no highly mineralized water was leaking from the closed mine. Later, perhaps in Sepember 1980 increased hydraulic head behind the clay dike caused the mine water to seep out and degrade the stream-water quality. In order to investigate leakages, dye was injected into two wells that penetrated the closed mine complex 88. One injection revealed that the dye moved to a discharge point at a nearby mine entrance known to be connected to complex 88. No discharge of dye was detected as a result of dye injection into the other well during the project. Acidic mine water continues to seep from the closed mine complex 88. A definitive evaluation of the effects of reclamation on the area's water quality cannot be made until the hydrologic system stabilizes.