One of the largest Superfund sites in the country, Silver Bow Creek/Butte area encompasses more than 500 underground mines and four open pit mines, including the Berkeley Pit with its ancillary tailings ponds, waste dumps and acid leach pads. The Berkeley Pit — which has since been flooded with acidic, metal-contaminated water — might just be the pit from hell. The water contains so much dissolved metal that materials can be mined directly from the water. In 1995, a flock of migrating snow geese died in the Berkeley Pit. Necropsies found that the acid water had eaten away at esophageal tissue and damaged internal organs.
In fact, the area, designated as a Superfund site in 1983, has become such a symbol for toxicity that it has been transformed into a tourist attraction.
A water treatment plant has been built along the pit, capable of treating 5,000 gallons of water a minute. Even so, it is a race against time, as the water level is expected to reach the natural water table by 2020, which means the mine water will spill into the local groundwater.