First fish in 100 years swims past Milltown dam site

By JOHN CRAMER of the Missoulian - 04/10/2008

The first documented fish to swim upstream past the old Milltown Dam site in 100 years made the journey Tuesday, slipping through the dark waters and into the pages of history.

A rainbow trout tagged as part of a telemetry study migrated from the Clark Fork River below the dam and into the Blackfoot River less than two weeks after the defunct hydroelectric facility was breached as part of the Milltown Superfund cleanup project.

The trout is the vanguard of a mass migration coming this spring, when tens of thousands of fish reconnect with their historic spawning grounds on rivers flowing freely for the first time since 1908.

The young trout - No. 23-39, 13.4 inches long, 0.86 pounds, gender undetermined - is an otherwise unremarkable specimen that researchers had expected to stay downstream as part of a study about the impact of the dam's breaching.

David Schmetterling, a state fisheries biologist who has studied the dam's impact for a decade, said he was initially irritated about the young trout's decision to desert his downstream study.

“My first reaction was purely clinical, but on the other hand it's pretty cool,” he said. “I've handled hundreds of thousands of fish that had their migrations impeded by that dam, so it's very gratifying to be a part of this project.” Since early March, Schmetterling and his team have monitored the mortality and movement of nearly 500 caged and radio-tagged fish in the Clark Fork above and below the dam site and the Blackfoot and Bitterroot rivers.

Researchers tried to tag only sub-adult rainbow trout that were expected to stay in their current locations because they aren't ready to spawn.

None of the fish have died in the Milltown area, but two have moved large distances - the one that passed upstream of the dam and one that swam downstream to St. Regis - indicating that both were spawning.

Next week, researchers plan to capture 30 spawning-age fish upstream of the dam, implant telemetry devices, release them downstream, and monitor their passage back through the new river channel and the bypass channel during peak spring runoff.

Boulders have been placed in the channels to create resting and hiding places for fish, but the high volume and velocity of runoff could inhibit some fish from passing.

Also affecting fish will be the 300,000 yards of accumulated sediment moving downstream this spring.

That will be followed by an estimated 3 million more cubic yards of sediment, the largest load ever released by an American dam breaching, that will move downstream in coming years, killing a large number of fish in the short term but restoring the rivers' natural ecosystem in the long term.

For now, river advocates are applauding little rainbow trout No. 23-39, whose primordial urge to return to its ancestral home has put it into the spotlight.

Researchers noted nothing unusual in their data sheet about fish 23-39 when they captured it March 7 near the Sha-ron fishing access site a few miles below the dam.

They made a small slit in its belly, inserted a telemetry device, stitched up the incision and let it slip back into the cold waters, where it stayed with 15 other radio-tagged brethren in the rocky shallows until Tuesday.

When researchers went out Wednesday morning, they were surprised to find fish 23-39 had passed the dam site and found a new home near the Marco Flats fishing access, about three miles up the Blackfoot River.

“I was pretty disappointed at first because we'd lost one of our monitored population,” Schmetterling said. “We wanted them to be exposed to the (sediment) scour event downstream, but then I realized this is a pretty symbolic milestone.” Schmetterling e-mailed the news in his weekly fisheries update to Superfund project managers.

“Does this fish know how famous he (or she) is?” Russ Forba, the U.S. Environmental Protection Agency's Milltown Superfund project manager, responded jokingly.

Schmetterling responded in kind: “There is no doubt in my mind that this fish's selfish move was motivated by fame.” Schmetterling and Forba said later that while the first fish's dam-busting journey was a milestone, the true test for fish passage would come about June 1, when runoff is expected to peak.

Chris Brick, staff scientist for the nonprofit Clark Fork Coalition, said the first fish passage at Milltown was reminiscent of native trout returning to Silver Bow Creek near Butte and Anaconda, which marks the other end of the nation's largest Superfund complex.

“I'm thrilled to hear of this first fish event at Milltown, and now everyone's looking forward to the second and third and the thousands more to come,” she said.

Reporter John Cramer can be reached at 523-5259 or at johncramer@missoulian.com.