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After dam removal, Klamath restoration shows rapid habitat and fish recovery, researchers say
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Summary
Restoration contractors and partners reported rapid ecological responses in the Klamath River following removal of four dams, including expanded temperature variability, extensive revegetation and early Chinook returns documented by eDNA and multiple monitoring methods.
Caitlin Boise, aquatic ecologist with Resource Environmental Solutions, told attendees that the Klamath River Renewal Project removed four dams and began large-scale restoration of more than 2,000 acres of former reservoir bed. Boise said restoration work — from revegetation to large‑wood placement and tributary earthwork — began before full drawdown and continued through 2024–25.
Boise described a comprehensive monitoring network established for the project: USGS telemetered stations and project-installed gauges providing near‑real‑time continuous data across more than 230 river miles, paired grab‑sample locations for suspended sediment and water‑chemistry sampling, and a large eDNA program designed as a “molecular time capsule.” She said the team collected over 1,000 water samples at 45 locations across more than 70 river miles in a before‑after reference‑impact design.
The presentation highlighted water‑temperature changes immediately after reservoir drawdown. Boise said daily temperature ranges downstream of Iron Gate rose from differences of roughly 0.5–2°C before removal to 3–5°C after drawdown, restoring daily and seasonal variability that reservoirs had smoothed. She described this returned thermal regime as an important cue for salmon spawning and migration, and useful habitat improvements.
Boise showed photos of major tributary restoration: the Camp Scotch Creek Complex (≈8,000 linear feet, ~190,000 cubic yards of earthwork), Jenny Creek (≈3,000 linear feet; ~52,000 cubic yards) and Beaver Creek (≈6,000 linear feet; ~55,000 cubic yards with 28 beaver‑dam analogs). Much of the work aimed to reconnect tributaries with floodplains and create off‑channel refuge habitat.
On fish recolonization, Boise said project partners documented fish traversing the Iron Gate footprint days after in‑water deconstruction finished, and that Chinook presence has been detected upstream into Spencer Creek, Oregon, within weeks. She noted that Chinook were observed returning earlier in the 2025 season at sites including Jenny Creek and Spencer Creek — “about three weeks earlier than they did last year.”
Boise emphasized that multiple groups are conducting population monitoring (CDFW, USFWS and others) using telemetry, sonar, carcass and spawning surveys as well as eDNA and that the restoration contractor (RES) is responsible for restoring volitional passage across the 21 miles formerly under reservoirs. She closed by pointing attendees to a project story map and published analyses for more technical detail.
The presentation drew audience questions on sediment mobilization, invasive species management in revegetation, and open data dashboards. Boise said most water‑quality station data are available online via USGS stations, vegetation data may be published later, and that project teams are monitoring sediment transport and invasive species as part of mitigation and adaptive management.
Next steps for the project are continued monitoring, adaptive management of revegetation and sediment, and making datasets available to researchers and managers.
