Environmental Impacts at Fort Belknap from Gold Mining

This page was written by Erin Klauk as part of the DLESE Community Services Project: Integrating Research in Education.

Ruby Gulch flowing through Zortman, MT. Details

The Zortman-Landusky gold mine is a case study of the environmental risks of cyanide heap-leach gold mining and the impacts that these operations can have on communities, water and cultural resources. The Zortman-Landusky mine illustrates how modern mine operations continue to impact landscapes and leave behind massive environmental problems and liabilities. The mine experienced many problems, such as cyanide spills, and surface and groundwater contamination from acid mine drainage. This was one of the first massive cyanide heap-leach operations to open, as well as one of the first to close, leaving behind significant pollution and cleanup problems (Case Studies - The Effects of Mining ( This site may be offline. ) ).

In 1982, 2,953 liters of cyanide-tainted solution leaked from a containment pond and a section of piping used in the mine's cyanide sprinkling system ruptured and released 196, 841 liters of cyanide solution onto lands and creeks. The tap water revealed cyanide concentration levels above drinking water standards and the community's local water system was shutdown. Over the next two years, eight separate cyanide spills occurred. Without a permit, in September 1986, 75 million liters of treated cyanide solution was released onto 7 hectares of land when a solution pond was at risk of overflowing after a heavy rainstorm. Following one of the major spills, cyanide appeared in tap water in a mineworker's housing unit, just south of the mine, animals were found dead, and acid mine drainage contaminates nearly every stream drainage that emanates from the mine (Case Studies - The Effects of Mining ( This site may be offline. ) ).

Even though there were major environmental problems from the mining, the mining company, Pegasus, received only one fine for $15,000 in its first 16 years of operation. After years of unsuccessfully trying to address the environmental problems at Zortman-Landusky, local citizens and environmental groups sued Pegasus under the Clean Water Act, resulting in a 36 million settlement in 1996. Even with this settlement, cleanup funds for the mine were inadequate and citizens in the state were left with cleanup liability of tens of millions of dollars. In 1998, Pegasus went bankrupt (Case Studies - The Effects of Mining ( This site may be offline. ) ).

Although the mines are no longer in operation, tribal water resources continue to be threatened by acid mine drainage that occurs when sulfide rocks uncovered by the mining process produce sulfuric acid after exposure to rain and snow, and the mine sites contain vast quantities of sulfide rock (Final Report of the State - Tribal Relations Committee). The severe acidity of the water will require water treatment, but there is currently only enough funding for treatment until the year 2028 (Final Report of the State - Tribal Relations Committee).

Landusky Mine as viewed from the south. Details

To further investigate environmental impacts from gold mining on the Fort Belknap Indian Reservation, follow the links below.

Investigate the Environmental Impacts on the Fort Belknap Indian Reservation

Resources containing information about the environmental impacts of the Fort Belknap Indian Reservation.

For ideas on how to use these webpages in a classroom, a Study Guide is provided.