Pull to refresh
Logo
Chinook salmon reclaim most of former Klamath range after largest US dam removal

Chinook salmon reclaim most of former Klamath range after largest US dam removal

Built World

Four dams down, 640 km of habitat reopened; 21,052 salmon returned in two seasons

Today: Human Progress highlights Klamath recovery

Overview

Updated 1 hour ago

Four 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.

Questions about this story

Free account needed to ask — your question is kept and asked for you right after sign-up. Answers are public.

No questions yet — be the first to ask.

Key Indicators

21,052
Chinook salmon passing upstream, 2024-2025
7,742 in the first run, 13,310 in the second.
88%
Historic Klamath range recolonized
Salmon reached 345 km of reconnected habitat at up to 1,250 m elevation.
345 km
Reconnected habitat used by salmon
Fish traversed dam removal sites, hydraulic corridors, and engineered fishways.
640 km
Total habitat reconnected by dam removal
The largest dam removal project completed to date.
4
Dams removed
JC Boyle, Copco 1, Copco 2, and Iron Gate, built 1918-1962.

Voices

Curated perspectives — historical figures and your fellow readers.

Ever wondered what historical figures would say about today's headlines?

Sign up to generate historical perspectives on this story.

Play

Exploring all sides of a story is often best achieved with Play.

Most of these play right now — no account needed. Sign up to save scores, keep a streak, and unlock Debate and Predict. Log in Sign Up
Predict 3 ways this could play out. Back the one you believe — contrarian picks score more when a scenario has a resolution date. Log in to play

People Involved

Organizations Involved

Timeline

January 1918 September 2026

8 events Latest: Today
Tap a bar to jump to that date
  1. Human Progress highlights Klamath recovery

    Today Media

    The study's findings reach a wider audience, framing the return as a rare environmental success story.

  2. Salmon recolonization study published

    Research

    Scientific Reports publishes peer-reviewed research documenting 88% range recolonization.

  3. Second Chinook run nearly doubles

    Species Recovery

    13,310 Chinook pass upstream, bringing the two-season total past 21,000.

  4. First spring-run salmon detected above former dams

    Species Recovery

    A tagged spring-run Chinook is detected moving back up the river toward Upper Klamath Lake.

  5. First Chinook run passes former dam sites

    Species Recovery

    7,742 Chinook salmon migrate upstream through the removal sites in the first fall season.

  6. Last Klamath dam breached

    Infrastructure

    Crews breach the final dam, Iron Gate, freeing the river for the first time since 1918.

  7. Klamath dam removal begins

    Infrastructure

    Crews start dismantling the four PacifiCorp dams, beginning with reservoir drawdowns.

  8. PacifiCorp builds four Klamath dams

    Infrastructure

    Hydroelectric 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.

July 1999

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.

Then

Striped bass, alewives, and Atlantic salmon returned upstream within months. The river's ecosystem shifted visibly within a year.

Now

The ruling established that FERC can weigh ecological costs against power benefits, creating a legal path used later for the Klamath.

Why this matters now

Edwards set the regulatory precedent that led to the Klamath agreement. The Klamath shows what that precedent can do at industrial scale.

September 2011 - August 2014

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.

Then

Salmon returned within months of the first breach. By 2016, over 4,000 Chinook were counted in the river, far exceeding pre-removal numbers.

Now

The Elwha became the proof point that large dam removal leads to rapid ecological recovery, influencing the Klamath decision.

Why this matters now

The Elwha showed salmon recolonize quickly when dams fall. The Klamath tests whether that holds at four times the scale.

October 2011

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.

Then

Chinook and steelhead returned within weeks. The river re-established its natural channel within months.

Now

Condit demonstrated that natural recolonization can be immediate when a barrier is fully removed, without fish passage structures.

Why this matters now

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.

Sources

(8)