"Mountaintop removal mining involves removing the top of a mountain in order to recover the coal seams contained there. This practice occurs in six Appalachian states (Kentucky, West Virginia, Virginia, Tennessee, Pennsylvania, and Ohio). It creates an immense quantity of excess spoil (dirt and rock that previously composed the mountaintop), which is typically placed in valley fills on the sides of the former mountains, burying streams that flow through the valleys. Mountaintop mining is regulated under several laws, including the Clean Water Act (CWA) and the Surface Mining Control and Reclamation Act (SMCRA). Critics say that, as a result of valley fills from mountaintop mining, stream water quality and the aquatic and wildlife habitat that streams support are destroyed by tons of rocks and dirt. The mining industry argues that mountaintop mining is essential to conducting surface coal mining in the Appalachian region and that it would not be economically feasible there if operators were barred from using valleys for the disposal of mining overburden. Critics have used litigation to challenge the practice. In a number of cases, environmental groups have been successful at the federal district court level in challenging permits for mountaintop mining projects, only to be later overturned on appeal. Nonetheless, the criticisms also have prompted some regulatory changes."
CRS Report for Congress, RS21421
National Agricultural Law Center: http://nationalaglawcenter.org/