Montana Dam Will Be Removed to Clear Arsenic Sediment

HELENA, Montana, December 21, 2004 (ENS) - Federal and state officials have decided to remove a hydroelectric dam that has trapped nearly a century's worth of sediments from mining, milling and smelting operations in Montana's Upper Clark Fork Valley. Those sediments, contaminated with arsenic, have polluted the drinking water supply for the community of Milltown and threaten the local fishery. The reservoir area behind the dam has been a Superfund site since 1983.

On Monday, after years of negotiating and public comment, the U.S. Environmental Protection Agency (EPA) and the Montana Department of Environmental Quality (DEQ) issued the final Record of Decision for the Milltown Reservoir Sediments Operable Unit of the Milltown Reservoir/Clark Fork River Superfund Site.

As outlined in the Record of Decision, the cleanup will remove the Milltown Dam, excavate 2.6 million cubic yards of the most highly contaminated sediments in the Milltown Reservoir, restore the Milltown drinking water supply within a decade, allow unrestricted fish passage, and return the Clark Fork and Blackfoot Rivers to their natural, free flowing state.

The decision is the culmination of years of negotiation between the EPA, the state of Montana, the Atlantic Richfield Company, and NorthWestern Energy.

Milltown Dam is a deteriorating 98 year old structure. (Photo courtesy USFWS)

"The decision we are announcing today is the clear result of strong leadership from EPA, the Governor and her cabinet, the Trustees, local officials, ARCO/BP, NorthWestern Energy, and many other organizations, as well as the hard work of the project staff," Roberts said. "We also recognize the incredible support of the Montana citizenry who continue to show us the vision for a very productive, safe and viable Clark Fork River."

The excavated sediments will be hauled by rail to the Anaconda Smelter Superfund Site for disposal. The remedy will be coordinated with natural resource damage restoration activities in the reservoir area, which will provide for a more natural channel and floodplain.

A second dam will also be removed to enhance fish survival. The Stimson Dam, located one mile upstream on the Blackfoot River, will be removed prior to removal of the Milltown Dam through a cooperative effort under the U.S. Fish and Wildlife Service National Fish Passage Program.

Consent Decree negotiations to determine who pays for and performs the work are ongoing and confidential, the EPA said.

This part of the Superfund Site covers 820 acres around Milltown. Ninety-one people live within one half mile of the site. The nearest house is about the length of a football field away.

Missoula, a major population center, is directly downstream of the dam and reservoir. The site is adjacent to the Milltown Dam, where the Big Blackfoot River joins the Clark Fork River. The rivers are used for recreational activities, such as fishing and boating, and the dam blocks the spawning runs of native bull and cutthroat trout.

In the stretch between Butte and Missoula lie four federal Superfund sites, the result of over a century of mining and smelting in Butte and Anaconda.

Human health is at risk when people drink that hazardous substances in the groundwater underlying the Milltown/Bonner area. In addition, aquatic life in the Clark Fork River is exposed to hazardous substances during ice-induced scouring events, high flows, and the potential contaminated sediment release that would accompany a catastrophic dam failure, the Record of Decision states.

Montana Governor Judy Martz, a Republican, supports the dam removal. She expressed confidence in the cleanup decision. “This cooperative cleanup action will not only benefit people today," she said Monday, "but more importantly, serve as a lasting legacy that will benefit future generations of Montanans, who will be able to enjoy the restored environment and recreational opportunities offered by the Clark Fork and Blackfoot rivers."

Montana Governor Judy Martz calls the Milltown Dam cleanup one of the major environmental issues of her administration. (Photo courtesy Office of the Governor)

On November 1, NorthWestern emerged from bankruptcy protection with a smaller debt load and a firm determination to clean up the Milltown mess.

Just three days before it emerged from bankruptcy, NorthWestern announced that the company would move ahead on the dam removal and sediment cleanup by amending its Federal Energy Regulatory Commission (FERC) license "as a good faith gesture to the parties and to the entire Missoula County community."

"We are committed to facilitating the favored EPA remedy, restoring the Clark Fork River, and addressing the concerns with endangered bull trout,” said Mike Hanson, NorthWestern’s chief operating officer. “We hope all interested parties will join in and support the efforts of NorthWestern and Atlantic Richfield in this regard.”

NorthWestern’s Chief Operating Officer Mike Hanson (Photo courtesy NorthWestern Corporation)

In May, Martz announced that NorthWestern Corporation would pay $11.4 million and transfer property rights for remediation and restoration at the Milltown Dam and Reservoir, according to an agreement filed with a Delaware bankruptcy court.

As part of the same bankruptcy agreement NorthWestern will reserve $3.9 million for payment to Montana for restoration work at the Milltown site.

In addition, NorthWestern will reserve $7.5 million to pay ARCO for remediation costs that the EPA and the state are requiring at the site for dam and sediment removal.

The Record of Decision is the culmination of many years of study, analysis, proposals and public involvement. In April 2003, the EPA issued an initial Proposed Plan and received over 4,000 public comments. After reviewing these comments, EPA made a number of changes and issued a Revised Proposed Plan in May 2004. EPA received nearly 800 comments on the Revised Proposed Plan, 98 percent of which favored EPA’s cleanup proposal.

Now that the Record of Decision is final, the planning, design, and site preparation will begin immediately, the EPA said. Infrastructure construction would occur in 2005 with dam removal planned for 2006.

Removal of up to 2.6 million cubic yards of contaminated sediment in the Reservoir would occur in 2006 and 2007. Channel stabilization, revegetation, and other restoration activities would occur 2007-2008.

A community group, the Milltown Redevelopment Working Group, is currently looking at options for future land use, building on the remediation and restoration efforts and will host an open house in January 2005 to present initial ideas to the public.

The Milltown Reservoir Record of Decision is available on EPA’s web page: http://www.epa.gov/region8/superfund/sites/mt/milltowncfr/reservoirou.html