Effects of surface coal mining on suspended-sediment discharge in a small mountain watershed, Fayette County, Pennsylvania

Data collected in the upper Stony Fork basin from July 1980 to November 1981 indicate that logging operations associated with block-cut surface mining temporarily increased suspended-sediment discharge of Stony Fork. However, the strip-mining operation did not increase the suspended sediment discharges of Stony Fork because of effective sediment-control measures. These controls included diversion control terraces and a large sediment-control pond. The 50-acre mine site yielded an average of 6.9 tons of sediment per acre, whereas, the sediment yield of the 2.5-square-mile study area was 0.13 tons per acre. During most storms, sharp rises in streamflow were accompanied by corresponding rises in suspended sediment concentrations. At the end of a storm, suspended sediment concentrations quickly returned to base-flow levels. Instantaneous stream discharge ranged from 0.02 to 146 cubic feet per second. Suspended sediment concentration ranged from less than 10 to 905 milligrams per liter. The highest daily mean suspended sediment concentration was 176 milligrams per liter. (USGS)