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EPA formalizes decision to remove Milltown Dam
Larry Morton of Missoula casts his line into the murky waters of the Clark Fork River below Milltown Dam on Tuesday afternoon. Almost a century after the dam was built, the U.S. Environmental Protection Agency called for its removal Tuesday.
Photo by MICHAEL GALLACHER/Missoulian

Milltown Dam is coming down.

Ninety-seven years after copper king William Clark blocked the confluence of the Blackfoot and Clark Fork rivers with a timber-crib dam, the U.S. Environmental Protection Agency on Tuesday called for the removal of Milltown Dam and with it, millions of cubic yards of polluted reservoir sediments.

The $95 million Superfund cleanup would rid Milltown's drinking-water aquifer of arsenic, eliminate the periodic release of fish-killing pulses of copper from the reservoir, remove the threat of dam failure, and restore a native trout migration route and free-flowing river confluence.

"This remedy is permanent," said John Wardell, chief of the EPA's Montana office. "Once it's implemented, you don't have to go back or worry about whether it continues to work."

As proposed by EPA and endorsed by the Montana Department of Environmental Quality, the cleanup would remove the most heavily contaminated sediments from Milltown Reservoir - about 2.6 million cubic yards of mine and smelter wastes carried down the Clark Fork River over the past century.

Arsenic in the sediments is a risk to humans and has, in fact, washed out of the reservoir and into the groundwater beneath Milltown. Copper in the sediments is a risk to trout in the river downstream, and has drastically reduced populations of more than a dozen native fish species.

Under the EPA's cleanup plan, hydraulic dredges would remove the toxic sediments and send them via slurry pipeline to a disposal site less than a mile downstream, on dry ground out of the 500-year floodplain. Another 4 million cubic yards of less contaminated sediments would remain in place, albeit out of the water and anchored with vegetation.

The Clark Fork River's channel would be re-contoured and moved slightly to the north, and the aging dam would be removed.

With the sediments and dam removed, natural processes would rid Milltown's aquifer of arsenic within four to 10 years. Residents there have not been able to drink from the groundwater directly beneath their homes for 22 years - since a county sanitarian discovered potentially deadly concentrations of arsenic in their tap water.

Use of a replacement water supply and a ban on well drilling in Milltown would continue until the aquifer was again pure, Wardell said. But eventually, residents would be able to drink freely - and safely - from their own wells.

The proposal released Tuesday suggested that sediment cleanup and subsequent dam removal might not be completed until 2010, then would be followed by restoration and redevelopment of the reservoir and two rivers' confluence.

A separate restoration plan is expected to be released by the state of Montana within the next month, and could include new riverfront parks and trails, a whitewater kayaking park, and extensive wetlands and wildlife habitat.

"It's a great day for the river and for communities alongside the river," said Tracy Stone-Manning, executive director of the Clark Fork Coalition, the river watchdog group that launched a "Remove Milltown Dam" campaign three years ago.

"We get to put a river back together," she said. "That's just stunning. There aren't many places in the West that have this kind of opportunity."

So, too, came the endorsements from Missoula city and county health officers and governing boards - all of which had lobbied for removal of the dam and reservoir sediments in recent years.

"The cleanup and removal of the Milltown Dam will be, in my opinion, a dramatic and very visible event in our state's history," said Peter Nielsen, environmental health supervisor at the City-County Health Department and a former director of the Clark Fork Coalition. "It will signify the end of a century of abuse and neglect, and the beginning of a new future based on clean water, restored fish and wildlife habitat, and remarkable environmental and economic assets that will be enjoyed by many generations to come."

NorthWestern Corp., the dam's owner since February 2002, also endorsed the cleanup plan, and will soon submit an application to the Federal Energy Regulatory Commission to surrender the dam's operating license.

Spokeswoman Claudia Rapkoch said NorthWestern is not in the electric generation business and was never interested in owning Milltown Dam, but was forced to take the dam when it purchased Montana Power Co.'s electric transmission network.

And while the company previously sided with Atlantic Richfield Co. in asking that the dam and reservoir sediments be left in place, NorthWestern now agrees with the EPA's dam-removal plan, Rapkoch said.

"The important thing to remember is that NorthWestern is not Montana Power," she said. "NorthWestern has been working cooperatively with all parties to reach a solution that is best for all Montanans and for the environment. NorthWestern did not necessarily share the views of Montana Power."

However, NorthWestern was bound by an agreement between Arco and Montana Power, which bought the dam's owner limited liability for the Superfund cleanup in return for its endorsement of Arco's dam-in-place, sediments-in-place cleanup plan.

The agreement governed NorthWestern's public pronouncements only until the EPA released its proposed cleanup plan.

Thus Rapkoch's announcement Tuesday morning: "NorthWestern supports the EPA's plan for the Milltown Reservoir and Dam. We recognize that this is the preferred alternative, and we've been working with EPA and others to go down this path."

The utility has set aside $10 million in a limited liability company to pay for removal of the dam, Rapkoch said. And it will continue to negotiate a final, binding agreement with EPA, Arco, the state of Montana and the Confederated Salish and Kootenai Tribes.

So, too, will Arco continue "working through to a settlement," Vice President Sandy Stash promised Tuesday. But the company - which is responsible for Milltown Reservoir's cleanup because of its 1977 merger with Anaconda Copper Co. - is opposed to the dam-removal, sediment-removal option.

"We continue to be concerned that the proposed remedy has the potential to cause more harm than good," Stash said. "An excavation or dredging operation of this scale in the middle of a river worries us a lot. That may be our unique perspective as a large company, but it does provide us with quite a bit of consternation."

The EPA's plan calls for hydraulic dredges to pull the most contaminated sediments from an 86-acre wedge immediately upstream from the dam. Those sediments are 25-feet thick in places, and are highly contaminated with arsenic and copper.

Eighty-five percent of the sediments would be pulled off the reservoir bottom by hydraulic dredges, then transported by slurry pipeline to a lined repository about 4,000 feet downstream - on 80 acres of land bounded by Deer Creek Road, Interstate 90 and the railroad tracks.

The remaining sediments would be excavated on dry ground, then mulched and hauled to the repository either by rail or truck.

All of the work, Stash said, would pose a risk to fish in the river downstream. "We view this as a high-risk operation in the middle of an active river," she said. "I wonder if we aren't permitting a mine here - taking all that sediment and gravel out of the river. We have a lot of concerns about an operation of that size in the middle of a river."

During the EPA's 90-day public comment period on the cleanup plan, Arco will continue to advocate leaving the dam and sediments in place, Stash said. "We continue to think that the risks of leaving the sediments in place have been over-estimated and the risks of removal have been under-estimated."

Still, the company is optimistic "given our track record in Montana" that an agreement will be reached outside of court, she said. "We are continuing the dialogue. We are looking at a lot of creative options, and feel like we'll be able to work through to a settlement that works for everybody."

Missoula County commissioners provided the counter-punch. "Arco-British Petroleum needs to step up to the plate and realize that this work needs to happen," said Commissioner Bill Carey. "We are very pleased with the EPA's proposed plan."

The cleanup will almost certainly create some short-term increases in sediment and heavy metals in the Clark Fork River, said Commissioner Jean Curtiss. "But it's not like we'll be the first community that ever removed a dam. There's a lot of experience out there we can draw on; there are people who know how to do this work without creating a lot of disturbance."

The construction impacts will be temporary and manageable, said Keith Large, the state of Montana's Superfund site manager for Milltown. "You can't make a cake without getting the kitchen a little bit dirty," he said. "But you mostly want to keep it in the bowl. The Milltown cleanup will be like any other construction project. Sometimes you have problems, and sometimes things go real smooth."

At the EPA, Milltown project manager Russ Forba said the amount of sediment released during construction would not permanently impact aquatic life downstream. Sheet pilings would be driven into the reservoir to seal off the most contaminated sediments from the river during construction, greatly limiting the impact.

"But I'm not going to sugar-coat it," Forba said. "During construction, a lot of things will occur. But we will monitor any impacts closely, and will react to anything that comes along."

"The long-term benefits are obvious," he said, "and that's our focus. The aquifer will recover. We'll have a free-flowing river and fish passage. There'll be no more ice scouring metals off the bottom of the reservoir. All of those things are pretty extensive long-term benefits."

Not until recent years did the EPA begin leaning toward removal of the sediments and dam. No one event or revelation convinced agency officials to advocate dam removal, Forba said, but rather a combination of events and revelations: the addition of bull trout to the endangered species list, the February 1996 ice event that scoured huge concentrations of copper off the reservoir bottom and killed an entire age class of fish downstream, increasing questions about the stability of Milltown Dam, the support of Missoula city and county officials and Gov. Judy Martz for dam removal, and the 10,000 comments sent to the EPA by Missoula residents, mostly advocating dam removal.

"It all added up," Forba said, "and we realized that we could truly clean up the river and the aquifer."

The decisionmaking process took 20 years, said Wardell, chief of the EPA's Montana office. "It's taken longer than I think any of us would have wanted it to, but we're where we need to be at this point and it's time to press forward."

"I am extremely pleased that the state and EPA are where they are today," Wardell said. "In a lot of ways, it's been a quick 20 years."

Reporter Sherry Devlin can be reached at 523-5254 or at

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