Milltown Dam
Encyclopedia
The Milltown Reservoir Sediments Superfund Site is part of the largest Superfund
complex in the western United States. Situated in the Clark Fork River Basin, the complex stretches from the Warm Spring Ponds area near Butte, MT to the Milltown Dam site east of Missoula, MT. It was added to the National Priorities List
in 1983 when arsenic groundwater contamination was found in the Milltown area. The contamination resulted from a massive flood in 1908 which washed millions of tons of mine waste into the Clark Fork River, ultimately ending up behind the Milltown Dam. The additional designation of the Clark Fork River between Milltown and Warm Springs Ponds in the Deerlodge Valley came in 1992.
dam
on the Clark Fork
river in Missoula County
, in the western part of the U.S. state
of Montana
. The dam was located about seven miles east of Missoula, Montana
, at the confluence of the Blackfoot River
with the Clark Fork. Built in 1908 by copper mining tycoon William A. Clark, it was meant to supply hydroelectricity to his sawmills in nearby Bonner, Montana. Clark's sawmills supplied the giant timbers used to shore up the walls of the mine shafts in Butte. Since the 1870s, the Anaconda
and Butte
areas had been mined as one of the richest deposits of copper sulfate ever found in North America. With the dam just months old, however, a record flood on the Clark Fork washed tons of toxic mining sediment downstream, where it settled at the base of the dam to remain until remediation began, with a cumulative total of around 6.6 million cubic yards of sediment contaminated with arsenic, lead, zinc, copper, and other metals in the former reservoir bed.
. Review began immediately by the EPA to determine the Potentially Responsible Party (PRP) and to develop a plan to fix the groundwater contamination problem. In 1977 Anaconda Copper was purchased by the Atlantic Richfield Corporation (ARCO
), which assumed liability for the damages. In 2000, ARCO was purchased by British Petroleum.
In 1992, through the action of committed citizens in the Deer Lodge Valley, the EPA designated the Clark Fork River upstream from the Milltown Dam to the Warm Springs Ponds part of the Superfund Site.
In 1995, the study of the extent of site contamination was completed by the EPA and ARCO. A subsequent a feasibility study to determine how to restore the Milltown groundwater. That study was halted, however, as the unusually wet winter of 1996 sent a large ice jam down the Blackfoot River
and into the Milltown Reservoir, causing a severe scouring of the contaminated sediment in the reservoir bed and caused a fish kill downstream. Fearful of a major uncontrolled release of water (and sediment), officials quickly drew down the level of the reservoir, stranding the ice pack before it could cause any more damage. The EPA immediately began to examine the extent of the damage, and after a contentious public discussion, it became clear that the threats of continued releases of contaminated sediments into the downstream fishery must be addressed in the final remediation plan.
In 2003 the State of Montana, through its Natural Resource Damage Program, drafted a conceptual plan for the restoration of the Milltown Dam site. In December 2004, the final remediation plan was released by the EPA, calling for the removal of more than two million cubic yards of contaminated sediment and the removal of the Milltown Dam. In August 2005, a consent decree was signed by the parties, allowing the project to move out of the planning phase and onto the ground. After over 20 years of study and litigation, work finally began on the Milltown Site on June 1, 2006 with a drawdown of the Milltown Reservoir. Contaminated reservoir sediments were hauled to an upstream repository near the town of Opportunity, a move opposed by some local residents.
Remediation is defined as the cleanup of hazardous substances to protect human heath and the environment. The remediation on the Milltown/Clark Fork River Site is being led by the EPA and it's chief contractor Envirocon. The remediation phase includes the removal of three million tons of contaminated sediment and the Milltown Dam itself. Remediation goals include the restoration of the Milltown Aquifer and the downriver water quality as well as the trout fishery through the confluence area. Work on the ground began in the summer of 2006 and the remediation phase should come to a close by December 2009, with the project leadership shifting over to the State of Montana for the restoration of the area.
Restoration
Restoration in the context of Milltown is the creation of a natural river and floodplain following dam and sediment removal. With funds gained through a Natural Resource Damage Program lawsuit against ARCO
, the State of Montana is leading the restoration of the confluence area to a natural state. Restoration work began in the summer of 2008 and ramped up as the sediment removal drew to a close. The restoration work includes the sculpting of a new river channel, the creation of fluvial wetlands, bank reinforcement, and reestablishment of natural vegetation cover. Restoration work is scheduled to be finished by 2012.
Redevelopment
Redevelopment is the effort to return former hazardous waste sites to productive use. The plan for the redevelopment of the Milltown area includes the creation of a state park with a trail system connecting the surrounding communities. In 2007 a conceptual design for the park was created in cooperation by the Milltown Superfund Redevelopment Working Group and the Montana Department of Fish, Wildlife, and Parks, the National Park Service Rivers and Trails Program, the Idaho-Montana Chapter of the American Society of Landscape Architects. In 2009 a grant proposal for the initial park development was submitted to the Natural Resource Damage Program.
Superfund
Superfund is the common name for the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 , a United States federal law designed to clean up sites contaminated with hazardous substances...
complex in the western United States. Situated in the Clark Fork River Basin, the complex stretches from the Warm Spring Ponds area near Butte, MT to the Milltown Dam site east of Missoula, MT. It was added to the National Priorities List
National Priorities List
The National Priorities List is the list of hazardous waste sites in the United States eligible for long-term remedial action financed under the federal Superfund program. Environmental Protection Agency regulations outline a formal process for assessing hazardous waste sites and placing them on...
in 1983 when arsenic groundwater contamination was found in the Milltown area. The contamination resulted from a massive flood in 1908 which washed millions of tons of mine waste into the Clark Fork River, ultimately ending up behind the Milltown Dam. The additional designation of the Clark Fork River between Milltown and Warm Springs Ponds in the Deerlodge Valley came in 1992.
About the Dam
The Milltown Dam 46°52′18"N 113°53′33"W was an earth-fill gravity-type hydroelectricHydroelectricity
Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy...
dam
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
on the Clark Fork
Clark Fork (river)
The Clark Fork is a river in the U.S. states of Montana and Idaho, approximately long. The largest river by volume in Montana, it drains an extensive region of the Rocky Mountains in western Montana and northern Idaho in the watershed of the Columbia River, flowing northwest through a long...
river in Missoula County
Missoula County, Montana
-National protected areas:*Bitterroot National Forest *Flathead National Forest *Lolo National Forest *Rattlesnake National Recreation Area-Demographics:...
, in the western part of the U.S. state
U.S. state
A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...
of Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
. The dam was located about seven miles east of Missoula, Montana
Missoula, Montana
Missoula is a city located in western Montana and is the county seat of Missoula County. The 2010 Census put the population of Missoula at 66,788 and the population of Missoula County at 109,299. Missoula is the principal city of the Missoula Metropolitan Area...
, at the confluence of the Blackfoot River
Blackfoot River (Montana)
The Blackfoot River, sometimes called the Big Blackfoot River to distinguish it from the Little Blackfoot River, is a snow-fed and spring-fed river in western Montana. The Blackfoot River begins in Lewis and Clark County at the Continental Divide, 10 miles northeast of the town of Lincoln...
with the Clark Fork. Built in 1908 by copper mining tycoon William A. Clark, it was meant to supply hydroelectricity to his sawmills in nearby Bonner, Montana. Clark's sawmills supplied the giant timbers used to shore up the walls of the mine shafts in Butte. Since the 1870s, the Anaconda
Anaconda, Montana
Anaconda, county seat of Anaconda City/Deer Lodge County, is located in mountainous southwestern Montana. The Continental Divide passes within 8 miles of the community with the local Pintler Mountain range reaching 10,379 feet...
and Butte
Butte, Montana
Butte is a city in Montana and the county seat of Silver Bow County, United States. In 1977, the city and county governments consolidated to form the sole entity of Butte-Silver Bow. As of the 2010 census, Butte's population was 34,200...
areas had been mined as one of the richest deposits of copper sulfate ever found in North America. With the dam just months old, however, a record flood on the Clark Fork washed tons of toxic mining sediment downstream, where it settled at the base of the dam to remain until remediation began, with a cumulative total of around 6.6 million cubic yards of sediment contaminated with arsenic, lead, zinc, copper, and other metals in the former reservoir bed.
Superfund Designation and Study
In 1981, through a routine Missoula County water quality study, four wells in Bonner that served 35 households, were found to be contaminated with heavy metals. The Environmental Protection Agency and the Montana Department of Environmental Quality closed the wells and began to look into the cause of the contamination of Milltown area groundwater. Two years later, in September 1983, it was determined that the contamination was the result of a buildup of heavy metal laden sediment from years of intensive mining upstream by the Anaconda Copper Mining Company. That finding resulted in the addition of the Milltown Dam Site to the initial National Priorities ListNational Priorities List
The National Priorities List is the list of hazardous waste sites in the United States eligible for long-term remedial action financed under the federal Superfund program. Environmental Protection Agency regulations outline a formal process for assessing hazardous waste sites and placing them on...
. Review began immediately by the EPA to determine the Potentially Responsible Party (PRP) and to develop a plan to fix the groundwater contamination problem. In 1977 Anaconda Copper was purchased by the Atlantic Richfield Corporation (ARCO
ARCO
Atlantic Richfield Company is an oil company with operations in the United States as well as in Indonesia, the North Sea, and the South China Sea. It has more than 1,300 gas stations in the western part of the United States. ARCO was originally formed by the merger of East Coast-based Atlantic...
), which assumed liability for the damages. In 2000, ARCO was purchased by British Petroleum.
In 1992, through the action of committed citizens in the Deer Lodge Valley, the EPA designated the Clark Fork River upstream from the Milltown Dam to the Warm Springs Ponds part of the Superfund Site.
In 1995, the study of the extent of site contamination was completed by the EPA and ARCO. A subsequent a feasibility study to determine how to restore the Milltown groundwater. That study was halted, however, as the unusually wet winter of 1996 sent a large ice jam down the Blackfoot River
Blackfoot River (Montana)
The Blackfoot River, sometimes called the Big Blackfoot River to distinguish it from the Little Blackfoot River, is a snow-fed and spring-fed river in western Montana. The Blackfoot River begins in Lewis and Clark County at the Continental Divide, 10 miles northeast of the town of Lincoln...
and into the Milltown Reservoir, causing a severe scouring of the contaminated sediment in the reservoir bed and caused a fish kill downstream. Fearful of a major uncontrolled release of water (and sediment), officials quickly drew down the level of the reservoir, stranding the ice pack before it could cause any more damage. The EPA immediately began to examine the extent of the damage, and after a contentious public discussion, it became clear that the threats of continued releases of contaminated sediments into the downstream fishery must be addressed in the final remediation plan.
In 2003 the State of Montana, through its Natural Resource Damage Program, drafted a conceptual plan for the restoration of the Milltown Dam site. In December 2004, the final remediation plan was released by the EPA, calling for the removal of more than two million cubic yards of contaminated sediment and the removal of the Milltown Dam. In August 2005, a consent decree was signed by the parties, allowing the project to move out of the planning phase and onto the ground. After over 20 years of study and litigation, work finally began on the Milltown Site on June 1, 2006 with a drawdown of the Milltown Reservoir. Contaminated reservoir sediments were hauled to an upstream repository near the town of Opportunity, a move opposed by some local residents.
The Three Rs of the Superfund Project
RemediationRemediation is defined as the cleanup of hazardous substances to protect human heath and the environment. The remediation on the Milltown/Clark Fork River Site is being led by the EPA and it's chief contractor Envirocon. The remediation phase includes the removal of three million tons of contaminated sediment and the Milltown Dam itself. Remediation goals include the restoration of the Milltown Aquifer and the downriver water quality as well as the trout fishery through the confluence area. Work on the ground began in the summer of 2006 and the remediation phase should come to a close by December 2009, with the project leadership shifting over to the State of Montana for the restoration of the area.
Restoration
Restoration in the context of Milltown is the creation of a natural river and floodplain following dam and sediment removal. With funds gained through a Natural Resource Damage Program lawsuit against ARCO
ARCO
Atlantic Richfield Company is an oil company with operations in the United States as well as in Indonesia, the North Sea, and the South China Sea. It has more than 1,300 gas stations in the western part of the United States. ARCO was originally formed by the merger of East Coast-based Atlantic...
, the State of Montana is leading the restoration of the confluence area to a natural state. Restoration work began in the summer of 2008 and ramped up as the sediment removal drew to a close. The restoration work includes the sculpting of a new river channel, the creation of fluvial wetlands, bank reinforcement, and reestablishment of natural vegetation cover. Restoration work is scheduled to be finished by 2012.
Redevelopment
Redevelopment is the effort to return former hazardous waste sites to productive use. The plan for the redevelopment of the Milltown area includes the creation of a state park with a trail system connecting the surrounding communities. In 2007 a conceptual design for the park was created in cooperation by the Milltown Superfund Redevelopment Working Group and the Montana Department of Fish, Wildlife, and Parks, the National Park Service Rivers and Trails Program, the Idaho-Montana Chapter of the American Society of Landscape Architects. In 2009 a grant proposal for the initial park development was submitted to the Natural Resource Damage Program.
See also
- Clark Fork River
- Anaconda CopperAnaconda CopperAnaconda Copper Mining Company was one of the largest trusts of the early 20th century. The Anaconda was purchased by Atlantic Richfield Company on January 12, 1977...
- ARCOARCOAtlantic Richfield Company is an oil company with operations in the United States as well as in Indonesia, the North Sea, and the South China Sea. It has more than 1,300 gas stations in the western part of the United States. ARCO was originally formed by the merger of East Coast-based Atlantic...
- British Petroleum
- Butte, MT
- List of Superfund sites in Montana