Doug Martin, who is coordinating the project for the state Natural Resource Damage Program, said the restoration objectives "cannot be met if the powerhouse is left in place."
Martin conceded, however, that there are a number of Milltown and Bonner residents who have asked that the powerhouse be preserved as a historic artifact, even after the dam is disassembled as part of the Superfund cleanup at Milltown Reservoir.
"To be blunt," Martin said, the powerhouse has to go because it sits in the five-year floodplain.
Every time the river overflowed its banks, water would pool behind the powerhouse, depositing sediments contaminated with heavy metals and mine tailings produced upstream in Butte and Anaconda, he said.
And that's exactly the problem state and federal agencies are trying to alleviate by excavating sediments from behind the dam and powerhouse and then removing the structures.
In fact, photographs from June 1908, when a 100-year flood nearly filled Milltown Reservoir with sediment, show a large pool of still water behind the powerhouse.
That area now holds the deepest and most contaminated sediments, and is the source of the arsenic that pollutes groundwater beneath Milltown.
As an alternative, Martin and consultant Gary Decker of West Water Consulting suggested that the historic features of the powerhouse, including its original generators, could be moved to higher ground and incorporated into a museum.
Restoration funds might even be available for construction of a museum, Martin said.
"Because it is so crucial to the restoration, we might be able to use restoration funds to re-establish the powerhouse somewhere else," he said. "That's my personal opinion, though, and I don't make those decisions."
Generally speaking, the public has responded favorably to the river restoration plan proposed last summer by the state, U.S. Fish and Wildlife Service and Confederated Salish and Kootenai Tribes, Martin said.
Most of the commenters have said they like the draft plan's emphasis on restoring a naturally functioning, self-maintaining river system and the use of native materials to stabilize channels, banks and floodplains.
The several dozen people at Thursday night's presentation and question-and-answer session also seemed to favor the draft plan.
Decker said engineers looked at other, similar rivers around the region as they designed a restored Clark Fork-Blackfoot confluence.
The proposal would put each river in a single channel, the Clark Fork meandering moreso than the Blackfoot, both free of dams restricting their flow.
Even before Milltown Dam was built to provide electricity for the Bonner sawmill and downtown Missoula, the railroad had already changed the rivers' historic look, Decker said.
The construction of Interstate 90 further limited the streams, forcing them into straightened, engineered channels.
Now comes the U.S. Environmental Protection Agency's cleanup plan for Milltown Reservoir.
The EPA has proposed excavating 2.6 million cubic yards of polluted sediments, then removing the dam so sediments do not collect once more.
That's the remediation work, Martin said.
The state's proposal is the next piece - the actual restoration of the rivers.
And while the EPA has proposed reconstructing the rivers in highly engineered, riprapped channels, the state is taking a more natural approach.
The rivers would meander a bit more, and their channels would be held in place with aggressive plantings of native vegetation and in-river structures made of rocks.
But they also would provide more fish habitat and recreational opportunities, said Pat Saffel, regional fisheries manager for Montana Fish, Wildlife and Parks.
The confluence, he said, would go from a still water, pikeminnow fishery to a moving water, native trout fishery.
"This is not going to be Rock Creek," Saffel said. "It's not as cold of water. But it will provide habitat for fish."
And without the dam, he added, fish will be able to move freely for the first time in nearly a century.
"And that will be a very good thing."
Reporter Sherry Devlin can be reached at 523-5268 or at sdevlin@missoulian.com
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