OLEM/OSRTI

Washington, DC 20460

 NATIONAL PRIORITIES LIST (NPL) ***NPL Site*** September 2016 

ANACONDAALUMINUMCO COLUMBIA Columbia Falls, Montana

FALLSREDUCTIONPLANT Flathead County

 Site Location:

The Anaconda Aluminum Co Columbia Falls Reduction Plant (also called Columbia Falls Aluminum) is a primary

aluminum smelting facility located in northwest Montana approximatelytwo miles northeast of Columbia Falls, in Flathead

County.

 Site History:

The Anaconda Copper Mining Company built the aluminum reduction facility and began aluminum production in 1955.

The Atlantic Richfield Company (ARCO) purchased the plant in 1978 and operated it until 1985 when it was sold to the

Montana Aluminum Investor’s Corporation. In 1999, Glencore acquired the company and operated until 2009 when

production stopped due to poor economic conditionsfor aluminum production. The property boundary currently includes

approximately 3,200 acres with an operational area of approximately 950 acres. The plant is currently not in use. 

 Site Contamination/Contaminants:

A byproduct of the aluminum reduction process is spent potliner which is known to contain cyanide and flouride. 

These compounds can leach into ground water. Spent potliner material was landfilled on site from approximately 1955 

to approximately 1985. Other landfills located at the site received various wastes throughout the lifespan of the 

plant, including air scrubber sludge, likely containing fluoride compounds. The ground water and percolation ponds at 

the site are contaminated with cyanide and fluoride, as well as other metals. 

 Potential Impacts on Surrounding Community/Environment:

Contaminants have been released into ground water beneath the site, as well as the Flathead River and Cedar Creek (both

located directly adjacent to the site). Cyanide has been detected in two nearby residential wells. Other homes within the

same neighborhood use domestic wells for their water source which may be at risk. Cyanide and metals, including 

fluoride and manganese, have migrated from the site and have been detected in the Flathead River. The Flathead

River is a fishery that supports a variety of fish, including the federally-designated threatened bull trout, the

federally-designated sensitive westslope cutthroat trout and other species that are harvested for human consumption. 

 Response Activities (to date):

Since proposal, the site owner, Columbia Falls Aluminum Company, has begun a Remedial Investigation at the site, 

pursuant to an Administrative Order on Consent with EPA. Ongoing site characterization includes soil, surface water 

and sediment sampling and installation of 44 ground water monitoring wells for future sampling. 

 Need for NPL Listing:

Previously collected data indicates the site warrants additional investigation and possible remediation of source areas, 

surface water, sediment and ground water. Other federal and state cleanup programs were evaluated but are not viable at

thistime. While the site owner has agreed to complete a Remedial Investigation and Feasibility Study, at this time, no party has committed 

in a legally binding agreementto implement a remedy at this site. Additionally, no party has provided financial assurance to ensure a remedy 

can be implemented. The site needs to be placed on the NPL to ensure a remedy is implemented. The EPA received a letter of support 

for placing this site on the NPL from Montana’s Governor. 

[The description of the site (release) is based on information available at the time the site was evaluated with the HRS. The description may 

change as additional information is gathered on the sources and extent of contamination. See 56 FR 5600, February 11, 1991, or subsequent 

FR notices.]

For more information about the hazardous substances identified in this narrative summary, including general information regarding the effects of exposure to 

these substances on human health, please see the Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs. ATSDR ToxFAQs can be found on 

the Internet at http://www.atsdr.cdc.gov/toxfaqs/index.asp or by telephone at 1-800-CDC-INFO or 1-800-232-4636.