Chinook salmon reclaim most of former Klamath range after largest US dam removal
Built WorldFour dams down, 640 km of habitat reopened; 21,052 salmon returned in two seasons
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Overview
Updated 1 hour agoFour dams on the Klamath River came down in 2024. Within two salmon runs, more than 21,000 Chinook salmon swam upstream past the former dam sites into 345 km of habitat that had been blocked for over a century.
Peer-reviewed research published August 27 in Scientific Reports confirms the fish reclaimed 88% of their historical range. Two remaining dams upstream, drought, and a fish parasite leave the recovery's long-term trajectory uncertain.
Why it matters
Salmon reclaimed 88% of their historic Klamath range within two years of the largest US dam removal, proving river reconnection works at the scale skeptics doubted.
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People Involved
Organizations Involved
The Oregon-based utility built the four Klamath dams between 1918 and 1962 and agreed in 2016 to surrender them for removal.
The nonprofit established to plan and execute removal of the PacifiCorp dams and restore the former dam sites.
The largest federally recognized tribe in California, which led the two-decade campaign to remove the dams.
Federal agency within the Interior Department that manages the Klamath Project's water infrastructure.
California's trout and salmon conservation organization, whose researchers documented the Chinook recolonization.
Timeline
January 1918 September 2026
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Human Progress highlights Klamath recovery
Today MediaThe study's findings reach a wider audience, framing the return as a rare environmental success story.
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Salmon recolonization study published
ResearchScientific Reports publishes peer-reviewed research documenting 88% range recolonization.
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Second Chinook run nearly doubles
Species Recovery13,310 Chinook pass upstream, bringing the two-season total past 21,000.
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First spring-run salmon detected above former dams
Species RecoveryA tagged spring-run Chinook is detected moving back up the river toward Upper Klamath Lake.
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First Chinook run passes former dam sites
Species Recovery7,742 Chinook salmon migrate upstream through the removal sites in the first fall season.
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Last Klamath dam breached
InfrastructureCrews breach the final dam, Iron Gate, freeing the river for the first time since 1918.
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Klamath dam removal begins
InfrastructureCrews start dismantling the four PacifiCorp dams, beginning with reservoir drawdowns.
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PacifiCorp builds four Klamath dams
InfrastructureHydroelectric dams block salmon from over 640 km of upstream habitat for more than a century.
Historical Context
3 moments from history that rhyme with this story — and how they unfolded.
Edwards Dam removal (1999)
The Federal Energy Regulatory Commission ordered removal of the Edwards Dam on Maine's Kennebec River after determining its power output was worth less than the fish passage costs it imposed. It was the first FERC-ordered removal for environmental reasons.
Striped bass, alewives, and Atlantic salmon returned upstream within months. The river's ecosystem shifted visibly within a year.
The ruling established that FERC can weigh ecological costs against power benefits, creating a legal path used later for the Klamath.
Edwards set the regulatory precedent that led to the Klamath agreement. The Klamath shows what that precedent can do at industrial scale.
Elwha River dam removal (2011-2014)
Two dams on the Elwha River in Olympic National Park, Washington, were dismantled at a cost of $325 million. The Elwha and Glines Canyon dams had blocked salmon from over 112 km of habitat for a century.
Salmon returned within months of the first breach. By 2016, over 4,000 Chinook were counted in the river, far exceeding pre-removal numbers.
The Elwha became the proof point that large dam removal leads to rapid ecological recovery, influencing the Klamath decision.
The Elwha showed salmon recolonize quickly when dams fall. The Klamath tests whether that holds at four times the scale.
Condit Dam removal (2011)
A 38-meter dam on Washington's White Salmon River was breached in a single demolition blast. It was the tallest dam ever removed in the US at the time.
Chinook and steelhead returned within weeks. The river re-established its natural channel within months.
Condit demonstrated that natural recolonization can be immediate when a barrier is fully removed, without fish passage structures.
Condit showed the speed of natural recovery. The Klamath's 640 km of reconnected habitat is 20 times larger, making the speed of this recovery more striking.
