Transforming an Ecosystem in Orange County
Commuters via I-5 and Metrolink may not be aware that barriers below this infrastructure have been problematic for an important ecosystem. Now a construction project along Trabuco Creek, the major tributary to San Juan Creek in Orange County, aims to give steelhead trout access to diverse habitats.
In the Cleveland National Forest, a five-year project is underway to remove 81 small-sized dams across four streams. Additionally, a high priority has been placed on the I-5 Trabuco Creek Fish Passage Project where a concrete-lined channel that spans a quarter of a mile runs below an array of five highway overpasses.
The degree of drop from these barriers as well as the rapid speed of the water flow in the area inhibits fish that only swim upstream at an average speed of about 7 miles per day, from getting through and up to important spawning grounds. It is one of the reasons that the southern steelhead trout was listed as an endangered species by the National Marine Fisheries Service (NMFS) in 1997.
Specific efforts to remove these barriers and replace them with fish-passage-friendly structures helps watershed recovery and will open up steelhead access to 15 miles of upstream spawning habitat.
The fish passage design has been funded by the California Department of Fish and Wildlife, National Fish and Wildlife Foundation, and Wildlife Conservation Board and is planned for completion by 2025.
Why this matters
Southern California steelhead, a unique form of rainbow trout, is a native aquatic species. They spend most of their adult lives in the ocean, but spawn in freshwater streams and rivers. There was a time when thousands of these fish swam through the Los Angeles River, Santa Ynez River, and other waterways.
When a species faces imminent extinction, it’s critically important that people should take notice. Back in 1998, then-CalTrout Executive Director Jim Edmondson explained during an interview with the Los Angeles Times why Californians should care: because steelhead is among the “most cost-beneficial and biologically important indicator species of the health of that watershed. They are the canary in the coal mine. Anything that happens in that watershed ultimately gets in the creek. The steelhead needs to live in the creek, the lagoon, and the ocean to fulfill its life cycle. It’s hard to imagine another species that provides that kind of barometer.”
Today, Dr. Sandra Jacobson, CalTrout’s South Coast Regional Director, explains, “When they disappear, that means there are probably multiple issues within a watershed.”
The I-5 Trabuco Creek Fish Passage Project will transform an ecosystem by creating a more natural gradient and pool structure. It will allow steelhead trout to again be able to access high-quality spawning grounds upstream.
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