Effects of coal mining on the water quality and sedimentation of Lake Tuscaloosa and selected tributaries, North River basin, Alabama

Lake Tuscaloosa, a reservoir on North River, is the primary source of water supply for the city of Tuscaloosa, Alabama, and surrounding areas. Between October 1982 and September 1983, 14 sites in the North River basin were sampled to determine if surface coal mining has impacted the quality of water in the lake and selected tributaries. Water draining mined basins showed increases in specific conductance, sulfate concentrations , and dissolved and total recoverable iron and manganese concentrations after mining started in 1975. Although water in the reservoir has become more mineralized with only an estimated 5 percent of the basin mined, total dissolved solids concentrations are still very low, ranging from 28 to 35 milligrams per liter at the dam. The quality of water at most sites was, except for pH, iron, and manganese, within secondary drinking water standards. The pH of water from streams draining either mined or unmined basins was generally less than 6.5. Sedimentation has occurred at most measured lake cross sections since impoundment. However, natural factors such as steep overland and channel slopes, may cause more sedimentation in the lake from unmined basins than from coal mining in a different basin. (USGS)