King salmon are continuing their return to the Klamath River, after the largest dam removal project in history. While some kings were spotted last year, the salmon have officially been observed in two Klamath tributaries—the Williamson and Sprague Rivers—above Upper Klamath Lake, the first time those fish have been there in over a century, according to Oregon Public Broadcasting (OPB).
The removal of three dams and reservoirs on the Klamath River has allowed fish to access historical spawning grounds they’ve been locked out of for more than 100 years. Key to the success of these returning fish has been the lower water temperatures throughout the river, thanks to dam removal.
“Perhaps the most immediate and vital sign of the river’s healing is the dramatic improvement in water temperature—a crucial factor for the Klamath’s ecosystem,” writes Cal Trout, a leading conservation organization in California. “The dams and their reservoirs created artificially warm water temperatures in late summer and fall, when fish were returning to the system to spawn, and excessively cold water in the spring, when juvenile salmon out-migrate to the ocean. Ongoing monitoring of water temperatures both pre- and post-dam removal shows that temperatures have returned to a more natural regime that provides improved conditions for salmon during adult spawning migration and juvenile outmigration.”
The Klamath is following a similar path to the Elwha River, in Washington State, which saw its dams removed and a quick repopulation of its steelhead and salmon.
While the spawning salmon are a welcome sight, conservationists and researchers urge caution in too much early celebrating. The king salmon that have spawned in the Klamath so far are on a three-year return cycle, according to OPB. That means the fish hatching in 2024 and 2025 won’t return until 2027 and 2028, which will give researchers a clearer picture of salmon survival and the overall health of the watershed.