Tuesday April 23, 2024

Cascade PBS

Every year, hundreds of muscular, sea-bright fish — chum salmon, chinook, coho, steelhead — push into the Columbia River from the Pacific Ocean, swim over 120 miles (200 kilometers) upstream, and turn left into Hardy Creek. They wend through rocky shallows shaded by alder and willow, cold water passing over flared gills. Plump with milt and eggs, they pump their tails furiously, striving for the graveled spawning grounds in southern Washington where they’ll complete their life’s final, fatal mission.

And then they hit the railroad.

In the early 1900s, Hardy Creek was throttled by BNSF Railway, the United States’ largest freight railroad network. When the company built its Columbia River line, engineers routed Hardy Creek under the tracks via a culvert — a 2.5-meter-wide arch atop a concrete pad. The culvert, far narrower than Hardy Creek’s natural channel, concentrated the stream like a fire hose and blasted away approaching salmon. Over time, the rushing flow scoured out a deep pool, and the culvert became an impassable cascade disconnected from the stream below — a “perched” culvert, in the jargon of engineers.

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