Arroyo Hondo Fish Passage

The project was a steelhead fish passage project consisting of installing cast in place concrete baffles in the large 16’ wide box culvert/tunnel under the state Highway 101 and Southern Pacific Railroad trestle. At the head of the tunnel a resting pool was created. Once finished, the velocity of the water flowing through the culvert was slowed enough at 16’ intervals to allow the fish to move through the tunnel to the spawning grounds under a much broader range of water flows than previously allowed by the pre-existing site conditions.

The project required careful planning and coordination with numerous agencies and monitors due to the presence of endangered steelhead trout, red legged frogs, tidewater gobies and various other species of concern.