The world’s largest dam removal project, located on California’s Klamath River, concluded in August 2024. Four hydroelectric dams—J.C. Boyle, Copco No. 1, Copco No. 2, and Iron Gate—were demolished after over two decades of advocacy.
The $450 million project reopened 420 miles of river habitat that had been blocked since 1918, marking an unprecedented victory for river restoration.
Century-Old Barriers Finally Fall
Built between 1918 and 1962, the four dams generated 163 megawatts of electricity, but they also devastated salmon populations. Iron Gate, standing 173 feet tall, was the last to fall.
The dams blocked migratory fish from accessing critical spawning grounds for over a century, resulting in a 90 percent decline in Chinook salmon populations and a 98 percent decline in spring Chinook populations.
Tribes Lead the Fight
The Yurok, Karuk, Klamath, and other Basin tribes spearheaded the removal campaign for decades. “We were told it would never happen,” said Frankie Myers, a Yurok tribal member.
Indigenous communities, for whom salmon are sacred, persisted despite skepticism, ultimately achieving what many deemed impossible through relentless advocacy and legal action.
Disaster Sparks Movement
In September 2002, over 60,000 adult salmon perished in the Klamath River below the dams due to low water flows and poor conditions.
This catastrophic fish kill served as a national wake-up call, galvanizing public support for dam removal and uniting tribes, environmental groups, and government agencies in a restoration effort.
The $450 Million Investment
PacifiCorp contributed $200 million while California provided $250 million for the removal. The utility company determined that removal costs less than upgrading the aging dams to current environmental standards.
The project became the most expensive dam removal in U.S. history, funded through ratepayer surcharges and state bond money.
Removal Timeline and Process
Copco No. 2 was removed in fall 2023. Reservoir drawdowns began in January 2024, with breaches following quickly.
The three remaining dams were demolished by August 2024, ahead of schedule. Contractors carefully managed the release of 5 million cubic yards of sediment while creating bypass tunnels to control water flow.
Salmon Return Within Weeks
Within the first week of dam removal, fish were detected passing the former Iron Gate Dam site. Remarkably, within just two weeks, Chinook salmon had reached Oregon spawning grounds.
By year’s end 2024, approximately 7,700 fish passed through the former dam site, with Chinook salmon comprising 96 percent of returning fish.
Historic Migration Restored
In October 2024, fall Chinook salmon were spotted in tributaries above the former J.C. Boyle Dam—areas they hadn’t accessed since 1912. Salmon reached the Williamson and Sprague rivers, traveling nearly 300 miles into the Upper Klamath Basin.
Video footage captured salmon ascending Keno Dam and entering Klamath Lake for the first time in over a century.
2025 Numbers Triple Previous Year
By mid-October 2025, the Shasta River counted 5,745 adult Chinook salmon compared to just 1,871 at the same point in 2024—a threefold increase. Between October and December 2024, an average of 588 fish per day passed the former Iron Gate site.
The rapid population response exceeded scientists’ expectations.
420 Miles of Habitat Unlocked
The dam removals reconnected habitat equivalent to the distance between Portland, Maine, and Philadelphia. Salmon now access cold-water tributaries with springs crucial for spawning success and juvenile survival.
This expanded habitat helps populations distribute across the landscape, increasing resilience against climate change, droughts, and wildfires.
Water Quality Transformation
The dams created stagnant reservoirs that fostered toxic blue-green algae blooms, rendering the water unsafe for swimming or drinking. Removal allows the river to aerate naturally, increasing oxygen levels and reducing algae production. Water temperatures are dropping as the river adjusts to its natural state.
Tribal monitoring stations document steady improvements in dissolved oxygen and turbidity levels.
Cooler Waters Support Salmon
Before removal, reservoirs acted as “heat batteries,” maintaining dangerously warm temperatures that persisted through summer and fall. Now the river cools naturally, creating healthier conditions for salmon and reducing disease outbreaks.
Temperature regulation benefits all aquatic species and improves overall ecosystem function, critical for fish survival.
Sediment Release Managed
Approximately 5 million cubic yards of sediment flowed downstream between January and October 2024, temporarily muddying the water.
Scientists expected this short-term impact, which concentrates sediment movement over months rather than years. Water quality is steadily improving. Similar projects, such as Washington’s Elwha River, have shown recovery within two years of completion.
Largest Revegetation Effort
Teams are planting 17 to 19 billion native seeds across 2,200 acres of former reservoir beds. The effort includes 96 species: white oak acorns, milkweed, poppies, lupines, and grasses. Over 300,000 tree and shrub plugs complement the seeding.
Yurok crews began collecting seeds five years prior to removal, partnering with nurseries to amplify seed production.
Nature Leads the Way
Resource Environmental Solutions and tribal crews hand-sow custom seed mixes designed by Yurok ecologists. Pioneer species stabilize soil while creating conditions for diverse plant communities.
The strategy, utilizing “facilitation patches,” helps native plants outcompete invasive species. By 2025, former reservoirs will bloom with wildflowers, attracting pollinators, while young pines will grow near dam sites.
Ecosystem Rebounds Rapidly
Bald eagles, otters, beavers, and ospreys have returned in greater numbers. The ecosystem is “coming alive almost instantly,” according to researchers. Fish returned in greater numbers than expected. Bears frequent the riverbanks.
Scientists document dramatic ecological shifts, characterized by increased biodiversity, throughout the watershed, demonstrating nature’s remarkable resilience when barriers are removed.
Cultural Rebirth for Tribes
For the Yurok people, salmon are central to their identity, ceremonies, and sustenance. The tribe dreams of reviving its annual salmon festival featuring Klamath salmon instead of Alaskan imports.
“The return of salmon filled me with joy reserved for weddings and births,” said Frankie Myers. Future generations may again witness salmon so abundant you could walk across their backs.
$18 Million for Restoration
NOAA awarded $18 million to the Yurok Tribe for the Upper Klamath River Tributary Post-Dam Removal Salmonid Restoration Project. An additional $1.9 million went to Oregon to evaluate fish passage improvements at Keno Dam.
These investments, funded through the Bipartisan Infrastructure Law and Inflation Reduction Act, support long-term monitoring and habitat restoration.
Monitoring the Recovery
Scientists use sonar cameras, radio tagging, and in-river sampling to track fish populations and habitat recolonization. Monitoring efforts involve partnerships among federal, state, tribal, and nonprofit organizations.
Data collection began years before removal, enabling a comprehensive assessment of ecological changes. However, recent federal funding cuts have challenged ongoing research efforts, threatening critical data collection and analysis.
A Model for River Restoration
The Klamath project sets a precedent for the $ 800 million allocated for dam removal in the Infrastructure Investment and Jobs Act. It inspires similar efforts on rivers like the Snake River in the Pacific Northwest.
In 2024, 108 dams were removed nationwide. The Klamath demonstrates that recovery happens faster than expected, offering hope for rivers worldwide.