Some animals win, some lose when the Potter Valley Project dams come down • The Mendocino Voice | Mendocino County, CA

MENDOCINO CO., 5/27/26 — For 104 years, the rainbow trout in the cold tributaries above Scott Dam have carried a secret they could not use. Pearse and Kannry’s genetic work, summarized in Friends of the Eel River’s 2025 comments to the state water board, shows the resident fish still hold much of the code for a sea-run life: the chemistry to slip downstream as smolts, turn silver, run to sea and come back heavier as summer steelhead, the southernmost ghost of Northern California’s runs. Two concrete plugs have kept that code from being tested. Once those plugs are removed, the trout can live out their code to run to the sea.

That is the smallest, strangest fact in the Potter Valley Project’s dismantling. Two rivers will live different lives once the dams come down. The Eel, bled for more than a century through a 9,257-foot tunnel under the divide, starts to regain itself; the Russian, drinking imported Eel water since 1908, learns to live thinner. The critters on both rivers are about to get the news.

This tour runs from the bare bottom of what used to be Lake Pillsbury down to the harbor seal haul-outs at Jenner: eight stations across two watersheds. Some critters win, some lose, and most will have to learn a different river.

Scott Dam holds back the upper Eel into Lake Pillsbury, a 2,300-acre reservoir completed in 1922. Under PG&E’s surrender and decommissioning plan, removal could begin as early as 2028. The lake bottom will be exposed, and what lived in the lake mostly does not live in the river.

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