David Schmetterling, research biologist with Montana Fish, Wildlife & Parks, told the Milltown Confluence audience that the dam's century-long presence severely disrupted historical fish migrations and degraded habitat for native trout, particularly bull trout.

The nut graph: Schmetterling said dam operations impeded both upstream and downstream fish movements, concentrated predators such as northern pike in reservoir habitat and trapped sediment that periodically released metals and caused fish kills. He described monitoring work showing large numbers of fish attempting upstream passage and documented improvements in spawning counts in some tributaries following dam removal.

Schmetterling summarized monitoring and management findings: early sampling captured tens of thousands of individual migrating fish in the late 1990s; trap-efficiency estimates suggested researchers were seeing about 25% of passage attempts, implying a total annual impediment on the order of hundreds of thousands of fish. He said targeted northern pike control measures (spring trap-netting and summer drawdowns) reduced pike density in the reservoir by roughly 88% during an intensive management period. After reservoir removal, pike recruitment to the downstream river sections "dropped to very low densities," Schmetterling said, and some upstream spawning streams (the North Fork and Montour Creek) showed increasing redd counts when compared with prior trends.

He described bull trout life history as especially vulnerable to barriers: migratory bull trout imprint on natal tributaries, rear there for multiple years, then migrate to richer downstream waters to grow before returning to spawn. Schmetterling reported that some monitored populations in the North Fork and Montour have shifted to increasing spawning trends since connectivity was restored, and juvenile bull trout were again being detected in river sections where they were effectively absent while the reservoir persisted.

Schmetterling framed monitoring and interim management (fish translocation, pike removal) as important stopgaps that informed long-term decisions but not as substitutes for the watershed-scale benefit of restoring connectivity through dam removal. He stressed that projects at this scale affect hundreds of miles of watershed and are important tools for species conservation, particularly under climate pressure.

Ending: Schmetterling urged continued monitoring and adaptive management while noting that recovery is a long-term process: "This is the place of big bull trout," he said of the confluence, and added that only sustained habitat connectivity and watershed-scale management will keep migratory trout populations viable.