Title
Issues Contributing to the Decision to Remove the Milltown Dam
Abstract
The Milltown Dam and reservoir are located about 2.5 miles upstream of Missoula, Montana at the confluence of the Blackfoot and Clark Fork Rivers. A 1908 flood filled the reservoir with sediments contaminated with metals from upstream mining and smelting operations. Arsenic contamination in area drinking water was discovered in 1981 by the Missoula City-County Health Department. The United States Environmental Protection Agency (EPA) listed the area on the federal Superfund site list in 1983. In 2003 Montana Governor Judy Martz, the United States Environmental Protection Agency (EPA) and the Montana Department of Environmental Quality (DEQ) called for the removal of contaminated sediments in the Milltown Reservoir and the removal of the Milltown Dam.
Factors leading to the decision to remove the dam included:
- A 1996 ice event scoured contaminated sediments and killed fish. Similar events occurred in the 1980's and 1970's.
- The bull trout was listed under the federal Endangered Species Act.
- The reservoir became populated with an invasive, predatory fish species.
- Electric energy deregulation led to the sale of the dam to a new owner.
- The dam became an unprofitable liability.
- Missoula County proposed ambitious cleanup and restoration goals known as the Two Rivers Restoration Project.
- Strong public support developed for cleanup and dam removal Dam safety evaluations caused concerns about leaving the dam and contaminated sediments in place.
- EPA and DEQ determined that cleanup and dam removal would restore the polluted aquifer, and prevent surface water and fisheries impacts from ice-scouring, floods or dam failure.
Start Date
1-4-2005 1:00 PM
End Date
1-4-2005 3:00 PM
Document Type
Poster
Issues Contributing to the Decision to Remove the Milltown Dam
The Milltown Dam and reservoir are located about 2.5 miles upstream of Missoula, Montana at the confluence of the Blackfoot and Clark Fork Rivers. A 1908 flood filled the reservoir with sediments contaminated with metals from upstream mining and smelting operations. Arsenic contamination in area drinking water was discovered in 1981 by the Missoula City-County Health Department. The United States Environmental Protection Agency (EPA) listed the area on the federal Superfund site list in 1983. In 2003 Montana Governor Judy Martz, the United States Environmental Protection Agency (EPA) and the Montana Department of Environmental Quality (DEQ) called for the removal of contaminated sediments in the Milltown Reservoir and the removal of the Milltown Dam.
Factors leading to the decision to remove the dam included:
- A 1996 ice event scoured contaminated sediments and killed fish. Similar events occurred in the 1980's and 1970's.
- The bull trout was listed under the federal Endangered Species Act.
- The reservoir became populated with an invasive, predatory fish species.
- Electric energy deregulation led to the sale of the dam to a new owner.
- The dam became an unprofitable liability.
- Missoula County proposed ambitious cleanup and restoration goals known as the Two Rivers Restoration Project.
- Strong public support developed for cleanup and dam removal Dam safety evaluations caused concerns about leaving the dam and contaminated sediments in place.
- EPA and DEQ determined that cleanup and dam removal would restore the polluted aquifer, and prevent surface water and fisheries impacts from ice-scouring, floods or dam failure.