Two years after the Klamath dams came out, more than 20,000 Chinook have gone home

The Klamath did not wait a generation. Active NorCal’s Sept. 15, 2026 recap of the first peer-reviewed recovery paper says that two years after the last of four dams was breached in August 2024, more than 20,000 Chinook have pushed upriver past the old dam sites onto spawning gravel their ancestors last used more than a century ago.

CalTrout’s Damon Goodman led the Scientific Reports study. Chinook reoccupied close to 90 percent of historic range in two migratory seasons. Coho, steelhead, and Pacific lamprey showed up above the former barriers in the first year. The reservoirs behind J.C. Boyle, Copco 1, Copco 2, and Iron Gate had run warm and grown toxic algae; with the river free, water cooled. This is the same basin that lost more than 33,000 adult Chinook in the 2002 die-off.

Fish also found routes nobody designed for them. No fall-run salmon were confirmed past Oregon’s Keno Dam in 2024. In 2025 a camera counted 2,497 through Keno, and 210 more past Link River Dam into Upper Klamath Lake. The Bureau of Reclamation is working with Oregon and NOAA on passage at those remaining dams. The paper also opens a door CalTrout has watched for years: a possible spring-run Chinook return, unseen near Iron Gate since the 1970s.

The sonar paper itself — Rewilding the upper Klamath River Basin: rapid recolonization of Chinook salmon following the world’s largest dam removal — is Scientific Reports 16:25322 (2026).

This is a The Gillnet news desk summary, not a reprint.

Source: Active NorCal — Two Years After the Klamath Dams Came Down, More Than 20,000 Salmon Have Gone Home (Sept. 15, 2026). Also: Goodman et al., Scientific Reports — Rewilding the upper Klamath River Basin.