Clark Fork River Operable Unit
National Priorities List (NPL) History
Site Type: Final NPL
City: Deer Lodge
ZIP Code: 59722
EPA ID: MTD980717565
The Milltown Reservoir/Clark Fork River Superfund Site is divided into three Operable Units: Milltown Reservoir Sediments, Milltown Water Supply and Clark Fork River. The focus of this page is the Clark Fork River Operable Unit.
In 1992, EPA designated the Clark Fork River, from the outlet of Warm Springs Ponds (see detailed map – opens in pop-up) to upstream of the Milltown Reservoir, as a distinct operable unit of the Milltown Reservoir Superfund Site. An investigation into the nature and extent of contamination of the Clark Fork River began in 1995. EPA notified Atlantic Richfield Company of its liability and entered into a Consent Order with ARCO to conduct a Remedial Investigation and Feasibility Study. In 2000, EPA ordered ARCO to conduct a time-critical removal action to address immediate human health risks for residents of Eastside Road in Deer Lodge.
EPA released a proposed plan for cleanup in August 2002. The cleanup proposal included a combination of removal and in-place treatment of tailings and contaminated soil, followed by revegetation. Stabilization of eroding streambanks is an important part of the remedy, because they contribute approximately 60 percent of the pollutants to the river. Remedial actions are proposed primarily for Reach A (Warm Springs Ponds to Garrison), and parts of Reach B (Garrison to Drummond). EPA invited public comment on the proposed plan for 120 days and received nearly 2,000 comments. A Record of Decision or ROD was signed in April of 2004.
EPA concluded settlement discussions with ARCO and the State of Montana in an effort to settle cleanup responsibilities and costs associated with the remedy proposed in the ROD. The settlement also involves the state's natural resource damage plan, which will be implemented along with EPA's selected remedy. The Department of Interior's federal restoration plan, which addresses the Grant-Kohrs Ranch National Historic Site and BLM land, will also be implemented.
Consent Decree for the Clark Fork River Operable Unit Site
On February 7, 2008, a Consent Decree for the Clark Fork River Operable Unit Site was lodged with the Federal District Court in Montana. Public comments were received on the Consent Decree during a 60-day public comment period. The Consent Decree provides the structure for how Atlantic Richfield "cashed out" its cleanup responsibilities by providing over $168 million to the State of Montana, which will perform the remedy and restoration activities with EPA and NPS oversight. The Consent Decree and Montana/EPA Memorandum of Agreement provide the details of how the project will be performed.
The site risks for the Clark Fork River OU are described for both human health and environmental receptors. Contaminants present in the Clark Fork OU are from historic mining and smelting processes upstream of the Clark Fork River. Contaminants of concern include arsenic, cadmium, copper, lead, and zinc. Copper is the primary contaminant associated with environmental risk, and arsenic is the primary contaminant associated with human risks. Concentrations of metals and arsenic are quite variable within the floodplain of the Clark Fork River. In general, studies have concluded that the human health risks are low enough to be considered "acceptable," but the ecological risks are high enough to be considered "not acceptable."
|Media Affected||Contaminants||Source of Contamination|
|groundwater||arsenic, cadmium, copper, lead, and zinc||historic mining and smelting processes upstream of the Clark Fork River|
Recognizing the importance of moving forward with cleanup on the Clark Fork River while the settlement negotiations continued, EPA initiated pre-remedial design level evaluation of the Clark Fork River OU using the Riparian Evaluation System (RipES) tool. This tool was developed as part of the ROD. The RipES work began with aerial photography of the river in May of 2006. Slickens and other impacted areas, and cultural features like roads and fences, were drawn onto the aerial photographs, and a base map was generated. In the years 2006, 2007 and 2008, EPA and its contractors verified this information on the ground, using more precise survey techniques. Some limited soil sampling was also performed to establish the depth and magnitude of contamination. The results of this effort provides EPA with an oversight tool that can be used to evaluate future Remedial Design and Remedial Action. Furthermore, application of RipES has generated information needed to develop both preliminary and final site-specific designs for individual properties.
Landowner input will be solicited so that issues such as fencing, livestock watering, and agricultural practices can be identified for consideration in developing site specific design plans. Data tables and maps will be developed in an electronic format that will eventually be available through the internet.
Now that enforcement proceedings are completed and some RipES information is available, Remedial Design will begin, and then Remedial Action construction will implement the selected remedy. The Montana Department of Environmental Quality (DEQ) will implement the remedial design and remedial action, with EPA and National Park Service help and oversight.
Community involvement plays an important role in the Superfund process. EPA uses a number of different tools and resources to promote effective, on-going, meaningful community involvement. The goals of the Superfund community involvement program are to:
- Keep communities affected by sites informed throughout the cleanup process
- Provide opportunities for communities to comment and offer their input about site cleanup plans
- Facilitate the resolution of community issues tied to a site
EPA recognizes that community involvement is key to achieving a successful cleanup of the Clark Fork River. In the past, EPA has conducted community interviews and issued several fact sheets. EPA has also funded a technical assistance work group called the Clark Fork Technical Assistance Committee to provide the public with independent technical reviews of EPA and DEQ Clark Fork River activities, reports, and meetings.
Public meetings have been held, and will continue to be held to provide the public with an opportunity for exchanging information with the agencies involved as the site progresses towards Remedial Action. These meetings will also provide EPA and opportunity to hear landowners' concerns and learn about current land management practices, and discuss how future cleanup activities may impact those operations.
EPA places a high priority on land reuse as part of its Superfund response program mission. The agency tries to select cleanup options that encourage and support future use of a site. EPA uses two fundamental methods to facilitate reuse of Superfund sites:
- Exploring future uses before the cleanup remedy is implemented, an approach that gives the Agency the best chance of designing cleanup remedies to support the likely future use of a site.
- Working with landowners and communities to remove barriers not considered necessary for the protection of human health or the environment at those sites where remedies are already in place.
One option for reuse is the siting of clean and renewable energy projects on contaminated (or formerly contaminated) lands. As part of this effort, EPA is evaluating the potential for energy projects on these properties and working with landowners and communities to identify ways to remove barriers to such projects.
Land Use Controls and Other Institutional Controls
Land use controls are the most common type of institutional control (IC). ICs are administrative or legal controls that help reduce the likelihood for human exposure to contamination. ICs can also help protect the integrity of the remedy. Examples of ICs are:
- Zoning ordinances
- Environmental covenants
- Deed notices
- Well-drilling restrictions
- Building permits
- Informational advisories
EPA or the lead agency conducts five-year reviews following the start of a Superfund cleanup when contamination is left on the site. These reviews are repeated every five years. We use these reviews to determine:
- How the remedy is working
- If the remedy remains protective of human health and the environment
You will need Adobe Reader to view some of the files on this page. See EPA's PDF page to learn more.
Consent Decree, February 7, 2008 (PDF, 167 pp, 313K)
ARCO Settlement Fact Sheet, January 2008 (PDF, 8 pp, 551K)
Site Specific Memorandum of Agreement, December 21, 2007 (PDF, 29 pp, 126K)
Clark Fork River Riparian Evaluation System (RipES): A Remedial Design Tool, April 2004 (PDF, 60 pp, 2.2MB)
RipES data and additional RipES documents are available at our contractor's website via the Links section below.
Record of Decision, April 2004
– Part 1: Declaration (PDF, 12 pp, 473K)
– Part 2: Decision Summary (PDF, 168 pp, 3.9MB)
– ROD Summary Fact Sheet (PDF, 4 pp, 119K)
– Responsiveness Summary (PDF, 142 pp, 1MB)
– Acronyms and Abbreviations, and References (PDF, 15 pp, 206K)
– A: Identification and Description of Applicable or Relevant and Appropriate Requirements (ARARs) (PDF, 41 pp, 308K)
– B: Clark Fork River OU Streambank Stabilization Design Consideration and Examples (PDF, 18 pp, 1.2MB)
– C: Clark Fork River OU BMPs and Riparian Management Plan Considerations (PDF, 10 pp, 220K)
– D: Clark Fork River OU Weed Prevention and Management Planning Information and Weed Species Fact Sheets (PDF, 47 pp, 877K)
– E: Grant-Kohrs Ranch National Historic Site (PDF, 43 pp, 664K)
– F: Concurrence Letter from State of Montana (PDF, 5 pp, 5MB)
Remedial Project Manager
U.S. EPA, Region 8, Montana Office
10 West 15th Street, Suite 3200
Helena, MT 59626
Montana Department of Environmental Quality
Lee Metcalf Building, Main Office
1520 East Sixth Avenue
PO Box 200901
Helena, MT 59620
Clark Fork River Riparian Evaluation System (CFR RipES) Website
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