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Clark Fork River Lawsuit History and Settlements

Preliminary Conceptual Restoration Plan – Butte Area One (2-2-2015)Montana v. ARCO 1999 | Milltown Dam 2005 | Montana v. ARCO 2008 | Mike Horse Dam 2008 | East Helena 2009

In 1983, the State of Montana filed a lawsuit against the Atlantic Richfield Co. (ARCO) for injuries to the natural resources in the Upper Clark Fork River Basin. The lawsuit, brought under federal and state Superfund laws, sought damages from ARCO, contending that decades of mining and smelting in the Butte and Anaconda areas had greatly harmed natural resources in the basin and deprived Montanans of their use.

In 1989, the Environmental Protection Agency (EPA) filed another lawsuit to establish ARCO’s liability for remedial clean up of the basin. The state has settled its lawsuit through a series of settlement agreements completed in 1999, 2005 and 2008.

1999 Settlement – Montana v. ARCO

The first phase of the lawsuit went to trial in March 1997. The state and ARCO reached a settlement agreement on a large portion of the lawsuit in June 1998. In November 1998, the state, ARCO, federal government and Confederated Salish and Kootenai Tribes reached a second agreement that incorporated the NRD settlement and also a settlement of ARCO’s remedial liability to EPA and the state for cleanup of Silver Bow Creek. The Court approved both settlement agreements in April 1999.

The 1999 settlement called for ARCO to pay the state $230 million ($215 plus $15 million in interest). The payment included:

  • $129 million (including $9 million in interest) for the restoration of natural resources in the Clark Fork Basin. This money was deposited in a special revenue fund known as the Upper Clark Fork River Basin Restoration Fund.
  • $86 million (including $6 million in interest) for the state’s cleanup of the Silver Bow Creek area west and north of Butte in accordance with EPA’s Record of Decision.
  • $15 million to reimburse the state for all of its costs in bringing the lawsuit through December 31, 1997.

As of December 2010, the Governor has approved 121 grants totaling $112million of the 1999 settlement funds.   In May 2012, the Governor approved a Final UCFRB Process Plan , that describes the new process the State will use to develop restoration plans and fund restoration projects in the UCFRB with the estimated $110 million remaining from the 1999 settlement.

2005 Settlement – Milltown Dam

A consent decree involving the state, EPA, ARCO and NorthWestern Corporation was filed in August 2005. The decree addressed the terms and costs of cleaning up the Milltown Dam Reservoir area east of Missoula and restoring the Clark Fork and Blackfoot Rivers at the site.

Under this Consent Decree, the State received approximately $13 million in total value for its natural resource damage claims, including the following:

  • $3.9 million for natural resource restoration from NorthWestern Corporation.
  • NorthWestern’s land (415 acres) and water rights at the site (2,000 cfs), which have an estimated value of about $2.5 million
  • a covenant from the U.S. Department of Interior (DOI) that the State’s restoration of this site will meet Montana’s bull trout obligations to DOI under the Streamside Tailings Consent Decree (value about $1.4 million)
  • implementation by ARCO’s contractor, Envirocon, of the State restoration plan at the site in the remediation project area (value about $5 million)

In addition, under the provisions of this Consent Decree, Montana is adding $7.6 million from the 1999 ARCO settlement for restoration at the Milltown site. For further information on the progress of the cleanup, go to the Milltown Dam page.

2008 Settlement – Montana v. ARCO

In February 2008, the state, EPA and ARCO reached a final settlement totaling $169 million. Of that, $96.5 million goes to DEQ for remediation of the Upper Clark Fork River site and $72.5 million goes to the state to restore the three remaining sites:

  • Butte Area One – $28.1 million
  • Smelter Hill Uplands – $13.2 million
  • Upper Clark Fork River – $26.7 million

Butte Area One Claim and Restoration Plan

Now Available:
Preliminary Conceptual Restoration Plan Butte Area One (2-2-2015)

Butte Area One extends from the upper end of the Metro Storm Drain downstream to the former location of the Colorado Tailings along Silver Bow Creek in Butte. The wastes in this area from mining-related operations have injured the area’s surface and groundwater resources.

Butte Area One is a portion of the larger Butte Priority Soils Operable Unit (BPSOU), an area of approximately 3,200 acres designated as a Superfund site by the EPA.

The extent of alluvial groundwater injury in Butte Area One is about 560 acres. The EPA Record of Decision, issued in 2006, is being implemented. Without effective remediation or removal of the sources of contamination, this area will continue to be contaminated for thousands of years. In addition:

  • contaminated groundwater enters Silver Bow Creek from the alluvial aquifer and
  • contaminated surface water enters Silver Bow Creek from storm water runoff flowing across mine dumps and soils within the BPSOU.

This contaminated water adversely affects water quality and aquatic life in Silver Bow Creek. The $28 million allocated to this site under the 2008 settlement is expected, along with the EPA remedy, to address this contamination.

In March 2012, the Governor approved the Butte Area One Final Restoration Process Planning Document . This document specifies the procedures, criteria, and schedule for the development of a restoration plan for Butte Area One injured, scheduled to be completed by the end of 2012.  In January 2013, the Governor approved the Final Butte Area One Restoration Plan following public input on a draft restoration plan.  The Butte Natural Resource Damage Restoration Council (BNRC) developed the process plan and the draft and final restoration plans, with the assistance from the Natural Resource Damage Program.

Smelter Hill Uplands Claim and Restoration Plan

From the 1880s to 1980, large volumes of hazardous substances were released into the air by the Anaconda Smelter. These emissions were deposited onto the land, resulting in severe loss of vegetation and injuring nearly 17.8 square miles of land in the mountains surrounding the city of Anaconda. The loss of vegetation resulted in widespread erosion, topsoil loss, degraded wildlife habitat and significantly reduced wildlife in the area. This claim area includes portions of:
  • Smelter Hill (4,653 acres)
  • Stucky Ridge (2,409 acres)
  • Mount Haggin Wildlife Management Area  (WMA) (4,304 acres)

The $13.2 million designated for this site under the 2008 settlement will address the most severely injured portions of these areas, including areas subject to the Anaconda Record of Decision.  The integrated remedy and restoration will be completed in 2013 at Stucky Ridge and parts of Mount Haggin, followed with subsequent monitoring.   Additional cleanup will be implemented over the next four years.

Upper Clark Fork River Claim and Restoration Plan

The aquatic and riparian resources of the Upper Clark Fork River from Warm Springs Ponds to the Milltown Reservoir have been degraded by a variety of hazardous substances that were released over the last 125 years from mining-related operations in the Butte and Anaconda areas.

The state determined that this contamination has caused drastically reduced trout populations in the Upper Clark Fork River as well as the loss of plants, wildlife and wildlife habitat along the river’s floodplain. The principal sources of contamination are:

  • tailings and contaminated soils in the Upper Clark Fork River floodplain, which affect thousands of acres, and
  • contaminated sediments in the river’s bed and banks.

The Natural Resource Damage Program will use the $96.5 million allocated to this site for restoration, which will be integrated into the remedial cleanup of the Clark Fork River.

Upper Clark Fork River Remediation Claim

In 2004, the EPA, with the state’s agreement, selected a final remedy for the environmental cleanup of the Upper Clark Fork River site. This cleanup plan calls for careful removal of contaminated tailings from areas devoid of vegetation because of contaminants, treatment of other affected soils and stream bank reconstruction.

The Montana Department of Environmental Quality, with EPA oversight and input, will use the $96.5 million for remediation of this site.

Grant-Kohrs Ranch and Remediation Claims

Grant-Kohrs Ranch, an historic unit of the National Parks System, lies along the Clark Fork River in Deer Lodge. As a result of contamination on the ranch, the National Parks Service asserted claims against ARCO for natural resource damage and remediation. The 2008 settlement provides funding from ARCO for cleanup of the contamination and restoration at the ranch. The Montana Department of Environmental Quality (DEQ), with National Park Service oversight, is responsible for the cleanup and restoration.

2008 Settlement – Mike Horse Dam

In April 2008, state and federal officials announced a $37 million settlement of litigation with Atlantic Richfield Co. and ASARCO LLC to remove the aging Mike Horse Dam and the contaminated tailings behind it, and to clean up and restore the Upper Blackfoot River and Mining Complex.  This MT Department of Environmental Quality website provides an overview of the project and status updates.

Under the terms of the settlement (PDF), ASARCO and Arco paid the state $8 million. The state also received a $19.77 million allowed claim in the ASARCO bankruptcy, and the U.S. Forest Service will receive $1 million to oversee the state’s implementation of the project and a $230,000 allowed claim for past costs.

The dam sits in a floodplain at the headwaters of the Blackfoot River, and the tailings behind it will be moved to a repository on higher ground on ASARCO property. The project will also include cleanup of tailings along the Upper Blackfoot River, Beartrap Creek and Mike Horse Creek and the state will restore those streams to eventually bring back westslope cutthroat and bull trout.

Under terms of a second settlement, ASARCO paid an additional $10 million into a custodial trust for perpetual water treatment of contaminated adit discharges from the abandoned mines located at the site. Use of this $10 million will be directed by the State in consultation with the U.S. Forest Service.

Mike Horse Background

Mining of the Mike Horse Mine began in 1898 and was expanded into a larger operation in 1919. In 1938, the Mike Horse Mining and Milling Company leased the mine and built a 150 tons-per-day flotation mill. In 1941, the Mike Horse Dam was built across Beartrap Creek to contain the tailings generated from the flotation mill.  In 1975, heavy rains caused a partial failure of the dam and high creek waters eroded contaminated tailings into Beartrap Creek and the Upper Blackfoot.

In 2005, a U.S. Forest Service Dam Safety Report determined that the dam was unsafe, and recommended that it be removed from service. In July 2007, USFS released an action memorandum (PDF) calling for the remMoval and disposal of the dam, mine tailings and wastes.

In 2008 the State of Montana and the U. S. Forest Service successfully reached a settlement with Asarco and Arco for environmental damages at the Mike Horse site. An agreement with the Montana Department of Environmental Quality (MDEQ), the Natural Resource Damage Program and the USFS, was reached soon after the settlement to coordinate cleanup activities at the site. MDEQ is the lead agency coordinating the cleanup.   In 2013 a repository was constructed to hold approximately 1 million cubic yards of mine wastes that will be hauled to the repository location over the next four years.  Information about the UBMC, including maps and fact sheets, can be found at DEQ’s website at

Draft Conceptual Restoration Plan

The State of Montana, Department of Justice, Natural Resource Damage Program (NRDP) completed a Draft Conceptual Restoration Plan for the Upper Blackfoot Mining Complex; Restoration of the Stream and Floodplain Ecosystem, a draft conceptual restoration plan for the Upper Blackfoot River and Mining Complex (UBMC) project area located in headwaters of the Blackfoot River about 15 miles east of Lincoln. The Montana Department of Environmental Quality (DEQ) is the lead agency in addressing the contamination at the UBMC site and is coordinating these remedial activities with the NRDP and the United States Forest Service. Currently, remedial actions related to removal of the Mike Horse Dam and impoundments, and removal of mining tailings associated with the UBMC, are in the planning stages. The Draft Conceptual Restoration Plan proposes general approaches to integrating restoration and remediation activities in an efficient and compatible manner in order to maximize benefits to the ecosystem and native fish habitat given the available funding resources. Through a 2008 settlement with ASARCO and Arco, the state obtained about $40 million for remediation and restoration of the UBMC site.

The timeframe for remediation and restoration actions at the UBMC is slated to occur over the next decade. As summarized in the Conceptual Restoration Plan, specific elements of the restoration vision include restoring stream channel and floodplain function, creating riparian conditions that exchange nutrients and other materials with the aquatic environment, and providing high quality habitat for westslope cutthroat trout and other aquatic and terrestrial organisms. Throughout the life of this project, continued coordination among the various state and federal agencies involved with remediation and restoration activities at the UBMC will be critical to achieving restoration goals at the site. This draft plan serves as a working document, and the first of several documents, that will culminate in a final restoration plan for the UBMC project area.

The State of Montana’s Natural Resource Damage Program is currently seeking comments on the Upper Blackfoot Mining Complex 50% Preliminary Restoration Design. This document outlines proposed restoration activities to be coordinated with Montana Department of Environmental Quality (DEQ) remedial actions related to removal of Mike Horse Dam and mine tailings at the Upper Blackfoot Mining Complex (UBMC) located in Lewis and Clark County, Montana, approximately 15 miles east of Lincoln, Montana.  This action is funded by a settlement that the State of Montana and the United States Forest Service (USFS) successfully reached with Asarco and Arco in 2008 for environmental damages at the UBMC.

DEQ is leading the cleanup efforts in coordination with the Natural Resource Damage Program and the USFS.  Cleanup actions at the site are expected to occur mainly over the next four years with removal of about one million cubic yards of mine waste materials that are present throughout the floodplain of the upper Blackfoot River.  The purpose of preparing this preliminary restoration design is to define the restoration vision for the site, which will be closely coordinated with DEQ cleanup activities.

Information about the UBMC can be found at DEQ’s website at .  The Preliminary Restoration Design is available on the NRDP website at -public-comment/  or by contacting NRDP at 444-0228.

Written comments on the Preliminary Restoration Design must be received by 5:00 p.m. on Thursday, April 10, 2014 and sent to NRDP via:

Email or

  • Fax (406) 444-0236 or
  • Mail at PO Box 201425, Helena, MT 59620

2009 Settlement – East Helena

Under the terms of the settlement (involving among others,  EPA and the State of Montana) was approved in December 2009 by the Court in the ASARCO bankruptcy case, as part of the plan of reorganization,   ASARCO paid the following amounts:

  • $100 million into a custodial trust to clean up and restore the smelter site and other lands in the East Helena area that had been owned by ASARCO.  The majority of this money was intended for use to clean-up and restore the groundwater under the smelter site and the city of East Helena.  In the event that there is money left in this trust after the East Helena cleanup is completed, that money may be used at the East Helena and other former ASARCO-owned sites in Montana for natural resource restoration.
  •  $15.2 million to EPA for the cleanup of yards and other lands in East Helena that are not owned by ASARCO.
  •  $5.9 million to the State to settle its compensatory NRD claims,  plus the conveyance to the State of 232 acres of ASARCO-owned land in the East Helena area to be used for wildlife habitat restoration, recreation and open space.  This money is to be used for restoration or replacement of injured or lost natural resources associated with the East Helena smelter site.

For additional information see

The Natural Resource Damage Program is presently seeking public comment on its proposed process for funding, out of the $5.9 million settlement, Early Restoration Projects.  All Early Restoration Projects must be time critical, of great importance, and no individual proposal will be funded for more than $100,000.  This process document is available for public comment through May 31, 2013.  Copies of this document are available  here (East Helena Proposed Process for Early Restoration ) or by contacting NRDP at 444-0205.    Written comments on the document must be received by 5:00 p.m. on May 31, 2013 and sent to NRDP via:

  •  Email or
  • Fax (406) 444-0236 or
  • Mail at PO Box 201425, Helena, MT  59620