A report by state Fish and Wildlife found that smelt had migrated above Bonneville Dam on the Columbia River, which hasn’t occurred since at least 1953.
The report sent by a state Fish and Wildlife biologist indicated an expansion factor that would estimate a few thousand were drifting back down through the smolt collection facility at Bonneville Dam. It’s possible the fish likely got up pass the dam through the locks.
According to one historical document, (Smith, Saalfeld. Studies on the Columbia River smelt. Washington State Department of Fisheries, Part 1:1953.) the smelt were occasionally seen as far upstream as Hood River.
After construction of Bonneville, the fish were seldom seen above the dam.
The last year of any above dam viewing was 1953, which was a large run year for the smelt. The aforementioned document speculated that the combination of run size and dam water temps of 40 degrees contribute favorably to the migration of the smelt to areas above Bonneville.
As of 2000, the 1953 date was still the last known above Bonneville passage.
The USACE website shows eight smelt were detected at the smolt collection facility in 2011 but no other observations.
The Columbia River and tributaries are now closed for all smelt fishing.