Mining can have devastating consequences for water supplies, typically resulting in rivers, lakes, and aquifers being contaminated with pollutants such as heavy metals and acidic water. This is commonly known as acid mine drainage, which occurs when exposure to air and water oxidizes certain substances (usually iron sulfide or fool’s gold). If left unchecked, the runoff from these mines can lower the pH of nearby streams to an unacceptable level.
Mountain top removal is another form of coal mining that is conducted mostly in Central Appalachia. This highly destructive process involves flattening entire mountains to uncover thin coal seams that are not accessible by traditional underground methods. After clear-cutting forests and removing vegetation, explosives are used to blast away the tops of mountains, sometimes destroying as much as 600 feet or more of elevation. The resulting debris is typically dumped into the valleys below. The practice has buried over 2,000 miles of headwater streams and polluted countless water sources, making them unusable.