Salmon Return to the Klamath After Historic Dam Removal

The Klamath River dam removal, completed in late 2024, reopened approximately 420 miles of historic salmon spawning habitat in northern California and southern Oregon — the largest river restoration project in United States history. Four hydroelectric dams that had blocked the river since 1964 are gone.

The Klamath enters the Pacific at the Humboldt–Del Norte county line, roughly 40 miles north of Trinidad. Its watershed covers 15,700 square miles, extending east into the Cascade and Siskiyou ranges and north into southern Oregon, and it is the second-largest river system in California by drainage area. For 60 years, Iron Gate Dam — the southernmost and most recently constructed of the four dams — held the river's downstream fish at approximately 190 river miles from the coast, while an additional 230 miles of historical spawning and rearing habitat sat above it, inaccessible to salmon that had no way in.

Lady Humboldt notes that the Klamath's return to a free-flowing state represents something more than a regulatory outcome: it is a reversal of a century of upstream obstruction that coincided with the steepest documented decline in the river's salmon populations. The fish did not go where they could not go. Now, in the second year after the dams' removal, they are beginning to find out what was there.

A broader seasonal overview of Humboldt County salmon windows — including the Klamath–Trinity run timing table and shore viewing context — appears in the seasonal wildlife field guide. What follows concerns the restoration specifically: which dams came down, what they blocked, and what the river corridor looks like now.

The Klamath's four hydroelectric dams were built between 1918 and 1964 by PacifiCorp for electricity generation. None was constructed with fish passage facilities that functioned adequately for the river's anadromous species.

• Copco 1 (built 1918, 130 feet high, Siskiyou County) — the oldest and most substantial California structure; its reservoir submerged a significant stretch of the upper Klamath canyon for more than a century
• Copco 2 (built 1925, 24 feet high, Siskiyou County) — a smaller diversion dam immediately downstream; removed first, in early 2024
• Iron Gate Dam (built 1964, 173 feet high, Siskiyou County) — the downstream anchor of the complex; its reservoir warmed to temperatures lethal to juvenile salmon and created the conditions enabling repeated ichthyophthirius multifiliis outbreaks in the river below
• JC Boyle Dam (built 1958, Klamath County, Oregon) — the northernmost structure, removed as part of the same coordinated effort

Fish ladders were installed at Iron Gate Dam after its construction, but the ladders proved inadequate for maintaining salmon access to the river above, and the reservoir temperatures — sustained by shallow, south-facing water exposed to summer solar heating — created persistent disease conditions for juvenile fish rearing in the lower reaches. The most acute expression of this came in September 2002, when low river flows combined with warm temperatures produced a die-off of approximately 34,000 adult Chinook salmon — the largest documented adult salmon kill in United States history at that time (Pacific Coast Federation of Fishermen's Associations, 2002).

Coordinated dam removal advocacy following the 2002 fish kill led, two decades later, to the Klamath Hydroelectric Settlement Agreement, the transfer of operating licenses to the Klamath River Renewal Corporation (KRRC), and the systematic drawdown and physical removal of all four structures between 2023 and late 2024.

The Klamath supports five native anadromous species — spring Chinook, fall Chinook, coho salmon, steelhead, and Pacific lamprey — each with distinct run timing, life history requirements, and habitat preferences in the upper river corridor now accessible to them.

Species	Run Timing (Klamath mouth)	Conservation Status	Post-Removal Habitat Gain
Spring Chinook (O. tshawytscha)	March – June	Species of concern (CDFW)	Upper Klamath mainstem + Sprague, Williamson tributaries (Oregon)
Fall Chinook (O. tshawytscha)	August – November	CDFW monitored; fluctuates with ocean conditions	First adults documented above former Iron Gate site, November 2024
Coho salmon (O. kisutch)	October – January	ESA Threatened (Southern OR / N. CA DPS)	Access to upper Klamath tributaries blocked since Copco 1, 1918
Steelhead (O. mykiss)	November – March	ESA Threatened (Northern California DPS)	Restored access to high-gradient upper river rearing habitat
Pacific lamprey (Entosphenus tridentatus)	Year-round (adult)	CDFW species of concern; culturally protected	Access to upper river; historically significant to Yurok and Karuk

Spring Chinook are, in Lady Humboldt's estimation, of particular consequence here. The spring-run ecotype — entering rivers months before spawning, holding in cold deep pools through summer before spawning in fall — was historically present in the upper Klamath and Sprague River systems in Oregon. It is the most cold-sensitive Chinook form and the most dependent on the undisturbed deep-pool habitat that formed at the former reservoir sites. Whether spring Chinook return to the upper basin on a timeline of decades or generations will depend on factors — ocean survival, sediment stabilization, water temperature in the newly free channel — that are, as of mid-2026, still being assessed by Yurok and CDFW monitoring crews.

Historical estimates place pre-dam Klamath Chinook runs at 500,000 to 1,000,000 adult fish annually, drawing on fish wheel records near the river's mouth from the late nineteenth century and reports from Yurok, Karuk, and Shasta tribal fisheries. By the mid-twentieth century, commercial harvest, dams, and habitat loss had reduced those runs to a fraction of their historical volume. The 2002 fish kill was the most acute event in a long trajectory; the 2006–2008 drought years brought additional run failures and coast-wide fishing closures.

The Klamath River Renewal Corporation's environmental review concluded that dam removal would, over a 30-year period, increase the abundance of Chinook salmon in the Klamath basin by 81.5 percent and coho by 53 percent compared to scenarios in which the dams remained in place (KRRC Environmental Impact Report, 2020). These projections rest on the river corridor above the former dam sites proving capable of supporting the species' full life-cycle requirements — an assumption for which 2024 and 2025 have begun providing evidence, and for which the full accounting will take considerably longer.

The Klamath River is accessible from several road corridors within and adjacent to Humboldt County. Each offers distinct views of the river and different seasonal windows for salmon observation.

Klamath River Overlook (Del Norte County / Redwood NP). A paved overlook road off U.S. 101, approximately three miles north of the Klamath River bridge, provides an elevated view of the lower estuary and the point where returning salmon enter fresh water from the ocean. Fall Chinook are visible at the river mouth from August through October from this vantage. The overlook is the same used for gray whale viewing — a productive early-morning stop on any northern Humboldt coast itinerary — and requires no hiking.

Requa Overlook (Del Norte County). At the north end of the Klamath River bridge on U.S. 101, a short trail leads to an overlook directly above the river mouth. Late-summer Chinook holding in tidal water before their upstream migration are visible in calm, clear conditions from shore.

Weitchpec (Humboldt County). The confluence of the Trinity and Klamath rivers at Weitchpec, reached via Highway 96 east from U.S. 101 at Arcata, is the most road-accessible mid-river observation point within Humboldt County. Fall Chinook at the confluence arrive from both rivers simultaneously in September and October; the combined run creates the highest fish concentration accessible from the county road system. The Highway 96 corridor passes through Yurok Reservation lands, and tribal fishing activity at the confluence during run season is part of the observable context. The hike directory includes several Trinity River access points along this corridor with river-level approaches.

Ishi Pishi Falls (Siskiyou County, near the Humboldt border). A natural cascade on the Klamath above Orleans, this historically significant Karuk fishing site is the most accessible observation point for salmon navigating the middle river reach. Fish are visible mid-water during the fall run from a short walk from the road. Cultural protocols at active tribal fishing sites warrant awareness; the Karuk Tribe's fisheries department posts guidance on access and observational context.

The Yurok Tribe — the largest federally recognized tribe in California, with a reservation extending along 44 miles of the lower Klamath River — advocated for dam removal for more than three decades before the removal licenses were secured. The Karuk Tribe, whose ancestral territory centers on the middle Klamath from the Trinity confluence to the Salmon River, filed legal interventions, participated in environmental review, and maintained independent salmon population monitoring throughout the process. Both tribes are now the primary biological monitoring bodies for the post-removal recovery: the Yurok Fisheries Department deployed monitoring stations in the newly accessible upper river, and Karuk tribal biologists documented the first confirmed fall Chinook spawning above the former Iron Gate Dam site in December 2024 — a development that, in the estimation of anyone who had followed the preceding three decades of advocacy, did not arrive by surprise.

Lady Humboldt notes that the Klamath salmon is not, for the Yurok people, a wildlife phenomenon to be observed from an overlook. The first salmon ceremony — a ritual of renewal and gratitude conducted at the beginning of each fishing season — has been central to Yurok cultural practice for centuries. When the spring Chinook run faltered across the decades of diminished returns, the ceremony did not. Its persistence represents a form of institutional memory that the dams could not obstruct, and of considerable consequence to those for whom that history is not merely recorded but lived.

The term for Chinook salmon in the Yurok language is kuehl. Its return to the upper river above what was Iron Gate Dam is something the Yurok have been waiting for since 1964.

The former reservoir sites — Copco Reservoir, Iron Gate Reservoir, JC Boyle Reservoir — are now sediment bars, gravel flats, and early successional vegetation. The drawdown of reservoir water in 2023 exposed lakebed sediments that had accumulated across decades of impoundment; these sediments are colonizing rapidly with willow, cottonwood, and native riparian plants. The Klamath River Renewal Corporation's vegetation monitoring, in partnership with Yurok and Karuk revegetation crews, tracked colonization across approximately 2,200 acres of former reservoir bed; willow establishment at the Iron Gate Reservoir site proceeded ahead of early projections (KRRC Restoration Progress Report, 2025).

Water temperature in the mainstem Klamath immediately downstream of the former dam sites has declined measurably since removal. Iron Gate Reservoir — shallow, south-facing, and exposed to summer sun — warmed the river to temperatures at which juvenile salmon mortality increased substantially. Summer 2025 temperature monitoring from the former reservoir reach showed average July readings 3°C to 5°C lower than pre-removal baselines at the same locations (CDFW Klamath Monitoring Program, 2025).

For observers approaching the river from Humboldt County via Highway 96, the most visible changes in 2025 and 2026 are in the riparian corridor itself: where the impoundments previously held still water, the river now runs. Sediment bars remain in the process of stabilization and plant colonization. Native grasses, willow thickets, and emergent aquatic vegetation represent the first stage of a recovery arc that biologists project will take several decades to approach a historical baseline.

The river is, in Lady Humboldt's estimation, operating on its own schedule and showing no particular concern about whether outside observers find that schedule sufficiently dramatic. The seafood guide covers the downstream consequences of healthy salmon returns — Dungeness crab, local fishing economy, and the Bay's harvest cycle — for those tracking the full food-web picture. The events calendar notes ranger-led programs timed to the fall salmon run, which carry current-season information not available from a reference guide.

How many dams were removed from the Klamath River, and when?

Four hydroelectric dams were removed: Copco 2 (early 2024), Copco 1 (September 2024), Iron Gate Dam (September 2024), and JC Boyle Dam in Oregon (2024). All were owned by PacifiCorp. The coordinated removal, completed by late 2024, is the largest dam removal project in United States history. The Klamath River Renewal Corporation managed the process under a settlement agreement negotiated among PacifiCorp, federal and state agencies, and tribal nations.

Which salmon species benefit most from the Klamath dam removal?

All five native anadromous species — spring Chinook, fall Chinook, coho, steelhead, and Pacific lamprey — regain access to approximately 420 miles of upstream habitat. Spring Chinook and coho salmon (ESA-threatened) are considered the ecotypes most likely to show significant population response, given their dependence on upper river cold-water habitat inaccessible since the dams' construction between 1918 and 1964. The Klamath River Renewal Corporation projected an 81.5 percent increase in Chinook abundance and a 53 percent increase in coho over 30 years following removal.

Where can observers watch salmon on the Klamath River from Humboldt County?

The Klamath River Overlook and Requa Overlook, both off U.S. 101 near the river mouth in Del Norte County, provide shore-based views of returning adult Chinook in August through October. The Weitchpec confluence of the Trinity and Klamath rivers (Highway 96, Humboldt County) holds the highest fall Chinook concentrations accessible by county road. Ishi Pishi Falls, near the Humboldt–Siskiyou line, is a historically significant site for the fall Karuk ceremonial fishing season.

When will salmon populations fully recover in the upper Klamath?

Projections from the KRRC environmental review indicate measurable increases in Chinook abundance within 10 to 20 years of dam removal, with longer timelines for spring Chinook and coho, which have lower population densities and longer ocean residence cycles. The first confirmed fall Chinook spawning above the former Iron Gate site occurred in December 2024. Full recovery toward historical run sizes would require sustained favorable ocean conditions and habitat quality across multiple salmon generations — a process measured in decades.

Lady Humboldt's weekly field guide covers the Klamath's salmon windows, Humboldt Bay tides, and the county's natural history calendar each Tuesday morning. A subscription is here, and it costs nothing.