The Fish Passage Facility at the Robles water diversion facility is a state-of-the-art fish ladder constructed by the Casitas Municipal Water District in 2005. 

It allows the endangered southern California steelhead to travel upstream of the Robles facility to prime spawning areas, which was not possible prior to 2005. It also lets fish swim downstream to the ocean. This federally mandated project is a collaborative effort by multiple agencies and community organizations. Agencies and organizations that supported the fish ladder project included the Association of California Water Agencies, Coastal Conservancy, Friends of the River, Matilija Coalition, Ventura County Watershed Protection Area, City of Ojai, Bureau of Reclamation, NOAA Fisheries, Association of California Water Agencies, and the California Department of Fish and Game.

The Federal agency, National Oceanic and Atmospheric Administration's National Marine Fisheries Service has identified in their Biological Opinion (BO) that less than 200 endangered steelhead trout remain in the Ventura Basin. Steelhead trout are dependent upon quality spawning sites that are no longer accessible in many streams and rivers throughout the California coastline. Upstream of the Robles Water Diversion Dam on the Ventura River are historic steelhead spawning areas. The fish ladder at the Robles Diversion Dam now provides access to spawning areas that were not accessible for over fifty years. 

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