Mining activities have long been known to cause significant
water quality impacts. Mining and drilling for fossil fuels
bring to the surface materials long buried in the earth,
including water. They also tend to generate large quantities
of waste materials or byproducts relative to the target
resource, creating large-scale waste disposal challenges.
Additionally, surface water may drain into mine openings, and
groundwater frequently accumulates in mines. Mine drainage
waters can be extremely polluted by salts in the groundwater
itself; metals such as lead, copper, arsenic, and zinc present
in the source rock; sulfur compounds leached from rock; and
mercury or other materials used in extraction and processing.
The pH of these drainage waters can be dramatically altered.
Some mine drainage is extremely acidic, with a pH of 2-3;
other source materials can lead to very alkaline discharges.
These contaminated drainage waters can devastate local
waterways, eliminating fish and rendering streams unfit
for human use. In the U.S. state of Colorado alone, some
23,000 abandoned mines have polluted 2,300 kilometers of