About Acid Mine Drainage
Acid mine drainage occurs after coal mining exposes metal sulfides to oxidizing conditions. It can occur in both surface and underground mining. Leaching of reaction products into surface waters pollutes over 20,000 kilometers (approximately 12,400 miles) of streams in the United States alone. Some of the most severe and widespread acid mine drainage is found in Pennsylvania and northern West Virginia. This section provides a description of how acid mine drainage is formed and what visual clues are used to identify it.