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Appalachian USA coal mines have been implicated as major stressors to aquatic life in headwater streams via discharge of total dissolved solids (TDS). This paper summarizes column leaching studies of spoils (n [ 50) and refuse and TDS effects on local water quality and biotic response. The initial pH of most materials is near-neutral. Initial specific conductance (SC) values range from 500–1,000 to [3,000 ls/cm, but 2/3 of materials drop below 500 ls/cm after several pore volumes of leaching. Studies of mining-influenced streams have found altered aquatic life, relative to natural conditions with no mining influence, at SC ranging from*200 to*700 ls/cm with depressed aquatic life consistently associated with elevated TDS;mechanisms causing such effects are under investigation. We suggest that active mine operations should be modified to place high TDS producing materials in ways that reduce contact with percolating drainage waters.