Below Keswick Dam on California's Sacramento River, salmon face a problem the dam itself created. Winter run Chinook salmon, now listed as endangered, once spawned across hundreds of miles of cold mountain streams before Shasta and Keswick Dams cut off access to that historic habitat entirely. Confined now to a much shorter stretch of river just below the dams, the fish depend on gravel beds to lay their eggs, yet the dam also blocks the natural flow of gravel that would normally replenish those beds over time. Since 2022 alone, state and federal agencies have responded by trucking in and placing more than 50,000 tons of gravel into the river near Keswick Dam, an ongoing effort aimed at rebuilding the spawning habitat the dam had quietly stripped away. This effort illustrates a broader reality of managing rivers reshaped by dams, that undoing decades of blocked natural processes often requires sustained, ongoing human intervention rather than a single restorative fix, especially for species with nowhere else left to spawn.
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