Upper Blackfoot Mining Complex (UBMC) / Mike Horse Site
Under the oversight of the Montana Department of Environmental Quality (MDEQ), the Montana Environmental Trust Group, Trustee of the Montana Environmental Custodial Trust (the Custodial Trust) is operating the water treatment plant (WTP) at the Upper Blackfoot Mining Complex (UBMC)/Mike Horse Site, which is situated at the headwaters of the Blackfoot River, in Lincoln, Montana. The WTP was designed and built by ASARCO to treat acid mine drainage from the UBMC that is contaminating the Blackfoot River. MDEQ, in consultation with the U.S. Forest Service (USFS), is the Lead Agency for the UBMC/Mike Horse Site under the 2009 Settlement Agreement for the Montana Sites under which the Custodial Trust assumed responsibility for site cleanup from ASARCO.
After the Custodial Trust assumed responsibility for operating and maintaining the facility, the Trust brought the UBMC WTP’s discharge water into compliance—for the first time in plant history—with Montana water quality laws designed to protect human health and aquatic life in the Blackfoot River. Approximately 26 million gallons of water of historic acid mining drainage is collected and treated at the WTP each year.
The Custodial Trust supports the MDEQ’s Superfund cleanup activities at the complex, including removal of approximately 800,000 tons of mine tailings and wastes.