Repopulation of anadromous fishes in the Upper Klamath Basin following dam removal

Year: 2022
Presenter/s: Mark Hereford
Symposium Session: 2022 - 06 Klamath River Dam Removal is the Largest and Most Complex Fish Restoration Project Ever Attempted
Topics covered: fish passage, fish-salmon, fish-steelhead, instream structure (culvert/bridge/dam), and monitoring


Anadromous fishes have been eliminated from over 400 miles of stream habitat in the Upper Klamath Basin since the construction of hydroelectric dams began on the Klamath River in 1912. Prior to construction of dams on the Klamath River, spring-run and fall-run Chinook Salmon, Coho Salmon, Steelhead Trout, and Pacific Lamprey occupied habitat in the upper basin. The four Klamath River hydroelectric dams that block anadromous fish are scheduled to be removed in 2023. It is anticipated with a high degree of certainty that fall-run Chinook Salmon, Coho Salmon, Steelhead Trout and Pacific Lamprey, which occur immediately below the lower-most hydroelectric dam, will repopulate habitat above the removed dams on their own. On the other hand, restoring spring-run Chinook Salmon to the upper basin will require a more active approach due to the lack of a source population immediately below the dams. In preparation for this large-scale restoration project, agencies, tribes, and other organizations are working together to formulate a strategy to monitor the natural repopulation of anadromous fishes into upper basin habitat as well as an active approach for restoring spring-run Chinook. The Upper Klamath Basin contains some of the most diverse and climate change resilient habitat in the Klamath River Basin due to the many groundwater-sourced streams. While a good portion of available habitat remains intact and currently supports resident salmonid populations, much of the available habitat has been altered since salmon last occupied it over 100 years ago. An adaptive approach to monitoring repopulation will be necessary to inform where habitat restoration is needed. This presentation will focus on a brief summary of the historical fisheries of the upper basin, describe the current habitat above the dams, describe species-specific approaches to repopulation, and summarize recent and on-going pre-dam removal studies that will help guide those approaches.