The process of mining the earth for coal and metal ores has a long history of rich economic rewards—and a high level of environmental impact to the surrounding aquatic and terrestrial ecosystems. Acid mine drainage is the highly acidic, sediment-laden discharge from exposed mines that is released into the ambient aquatic environment. In large areas of Pennsylvania, West Virginia, and Kentucky, the bright orange seeps of acid mine drainage have almost completely eliminated aquatic life in streams and ponds that receive the discharge. In the Appalachian coal mining region, almost 7,500 mi (12,000 km) of streams and almost 30,000 acres (12,000 ha) of land are estimated to be seriously affected by the discharge of uncontrolled acid mine drainage.

In the United States, coal-bearing geological strata occur near the surface in large portions of the Appalachian mountain region. The relative ease with which coal could be extracted from...