A Bridge Runs Through It

An ambitious cooperative barrier removal project will allow southern California steelhead access to core spawning and rearing habitat

By Sandra Jacobson

Southern California is the prism through which endangered species, water supply, transportation, public safety, flood control, residential development, and tribal influence and cultural history converge on the central challenge of maintaining healthy waterways for people and wildlife in urbanized coastal California. The Interstate-5/Metrolink fish passage project on Trabuco Creek in Orange County has all of these wrapped up into a final design package to protect endangered Southern steelhead from extinction. The project embodies the complexities of restoring steelhead migration, but also the progress that is being made to enable these native fish to coexist with people in this highly altered landscape.

Steelhead, the anadromous form of rainbow trout, are particularly sensitive to in-stream barriers like dams, diversions and bridges that block their migration between the ocean and headwaters where they reproduce. Steelhead move during high flows in the winter when streams open during sandberm breaching to restore connectivity with the ocean. Steelhead then enter the river system and migrate upstream typically 30 miles to freshwater headwaters in the mountains where they persist. The fish passage project at the Interstate 5 Bridge Array and Metrolink Railroad Bridge crossing Trabuco Creek addresses one of the most significant fish passage barriers in Southern California. Trabuco Creek is the major tributary to San Juan Creek, designated a high priority Core 1 population in the National Marine Fisheries Services (2012) Southern California Steelhead Recovery Plan.

This fish passage project is regionally unique in that it combines the latest in hydraulic engineering and infrastructure stabilization, with restoration of sensitive riverine ecosystems and recreational access. Implementation will restore steelhead access to their historic habitats 15 miles inland to headwaters. At the project sites, reme- diation of these barriers prevents further incision of the stream which threatens infrastructure, degrades aquatic and riparian habitat, and increases fine sediment loads downstream.

Over the past six years, this project has progressed through conceptual design, alternatives analysis, 65% development of the preferred alternative, physical model testing, and now into final design phase. The project team comprised of Northwest Hydraulic Consultants, Mike Love and Associates, Gannett Fleming, Stillwater Sciences timate and a multi-year agency comment log. Funding has been provided by California Department of Fish and Wildlife, National Fish and Wildlife Foundation, and Wildlife Conservation Board; and their support has been essential for success. and CalTrout, has extensive experience in solving challenging fish passage issues. Getting to final design is difficult both technically and operationally given the number of stakeholders with different viewpoints. The urban location adds complexity to address each party’s concerns for avoiding impairment of their mission or structures. The 90% design packages include a basis of design report, plans, technical specs, operation and maintenance manual (O&M), structural calculations, cost es-

The I-5 barrier is a leap and flow velocity barrier to aquatic species migration. The barrier extends 1,254 feet from the downstream drop within a natural channel, through a concrete double-barrel flood channel beneath an array of five bridges crossing Trabuco Creek, including the major artery, Interstate 5. As such, stakeholders are Orange County Flood Control District (OCFCD), California Department of Transportation (Caltrans), California Department of Fish and Wildlife (CDFW), National Marine Fisheries Service (NMFS), and local landowners. OCFCD and Caltrans priorities relate to public safety and property protection. Accordingly, their review focuses on maintaining flood conveyance and structural integrity of the concrete channel structure and the bridge piers. CDFW and NMFS priorities are wildlife protection, ecosystem integrity and regulatory compliance to achieve these goals. Their review focuses on design that maximizes passage and ecosystem integrity, and minimizes down-time for O&M.

The I-5 fish passage solution is a 650foot-long bypass chute and pool roughened channel fishway, connected to a 675-foot fish transport channel in the left bay of the existing concrete channel that runs under the bridge array. The key to the hydraulic solution is the flow split at the top which diverts increasing flow into the fish transport channel, while pushing higher flows, ing the limited time period of migration which can be as short as 72 hours over less than 10 days per year. likewise utilizes state of the art hydraulic design. It features a 420-footlong pool and chute roughened channel fishway, 130-foot-long rock ramp and turning pool, replacement of the undermined grouted rock drop structure and spillway beneath the railroad bridge, while stabilizing the eroded west bank, and creating a new equestrian trail crossing. It also includes restoration of the one-half mile natural channel between the current barriers to stabilize the channel, removal invasive species and integrate into the recreational trail system. sediment and urban debris into the main concrete channel. The lower fishway runs along the river left side of the channel, and features selectively placed rocks of various sizes which create pools and chutes for fish to rest during swim-through. It is important to avoid sediment accumulation in the structure which impairs passage dur-

The Metrolink barrier is a total leap barrier due to the 30 ft drop created through years of high flow that deepened the scour hole downstream of the bridge. Stakeholders include Orange County Transportation Authority (OCTA), the fee owner for the Metrolink railroad bridge. OCTA is a member of Southern California Regional Railroad Authority (SCRRA), who reviews the fish passage design to ensure that the design or construction does not impact its structure, or create maintenance issues. This is the main railroad artery for coastal California, known as the Metrolink which is the entity that operates the line and maintains the right-ofway. The city of San Juan Capistrano owns parcels of land surrounding Trabuco Creek channel at this location, and has jurisdiction on the soft bottom and riparian area, including the trail system.

There is also a residential development transaction in the mix in the vicinity of the Metrolink bridge. This transaction can help the City meet its affordable housing goals, and may contribute needed funds for long-term O&M for the fish passage project. Private landowners would provide construction access, and benefit from the stabilized channel that reduces channel erosion and loss of valuable property.

Moulton Niguel Water District has jurisdiction of its two greywater lines that run beneath the grouted riprap apron below the railroad bridge. Private landowners play a key role in providing construction access and legal documentation of deeds and easements. CDFW and NMFS review the Metrolink design package to ensure fish passage efficiency and regulatory compliance.

The Metrolink fish passage solution

It is an art to thread the needle on different missions held by parties directly invested in the outcome through the project. A Cooperative Agreement process is underway, led by CalTrout, involving up to 16 Parties and primarily involving Orange County. This Agreement lays out Roles and Responsibilities for each Responsible Party to provide passage through both I-5 and Metrolink barriers as they are jointly resolved. There are several new permitting pathways that offer expedited permitting for larger more complex restoration projects. One permitting pathway being pursued by our team is the State Water Board General Order, which is now being applied to several restoration projects statewide. This Order allows the lead agency to use their Programmatic Environmental impact Report (which discusses the impacts of a project in more general terms as opposed to a Project EIR), determine whether the project fits the Restoration Project definition, and determine avoidance and minimization measures compatible with the California Environmental Quality Act (CEQA). For California Endangered Species Act (CESA) Take coverage, an RMP (Restoration Management Permit) would be a good approach that CDFW can issue. It consolidates Take authorizations into a single permit, minimizing permit applications and fees, and authorizes Take during construction, implementation, O&M and ongoing

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The Osprey monitoring. The CalTrout-led petition for state listing Southern steelhead as an endangered species, currently under a one-year status review at CDFW, is further impetus to resolve these barriers now.

The fish passage project leverages concurrent removal of over 81 check dams in upper Trabuco Creek and San Juan Creek watershed. (See “Big Benefits from Small Dam Removal on the Cleveland National Forest” by Kirsten Winter, The Osprey, January 2022, https://www.ospreysteelhead.org/archiv es) Check dams are earthen and rock in-stream structures about 15 feet high, built in the mid-1900s for recreation. They are barriers to localized movement for aquatic species in response to threats of climate change such as fire and drought, and upon removal also improve access of steelhead to historic spawning and rearing area. This coast to crest ecosystem restoration is reminiscent of others underway in Southern California to benefit Southern steelhead (see www.caltrout.org).

The project is a prime candidate for funding the construction phase through federal Infrastructure Investment and Jobs Act (2022) and the Inflation Reduction Act (2022), which contain large carve-outs for climate change solutions. Awards from these sources can be used as cost share for funding from state fisheries and coastal resiliency grants programs. CalTrout is positioned to lead the funding campaign and construction, in a similar approach to the CalTrout-led $21 million Santa Margarita River bridge replacement and fish passage that began construction in 2023. The I-5 Metrolink construction would be phased, starting in

2024-2025 on Metrolink and middle reach, followed in 2025/2026 on the I-5 site for a three-year construction period.

The Trabuco Fish Passage Project occurs on the traditional lands of the Acjachemen Nation, the Indigenous People who historically inhabited lands that became Orange County, and whose descendants currently reside in Orange County and environs. We seek to partner with the Acjachemen in all aspects to implement this fundamentally important fish passage project to benefit an endangered species.

The Putuiden Village, adjacent to the I-5 barrier, is a silent and powerful reminder of wildlife and people that inhabited these coastal watersheds for thousands of years — and that breaking down barriers on all levels is needed not only to restore access and understanding of those that went before us, but to restore our watersheds for those that come after us. We’ve seen salmon and steelhead rebound in other parts of the country where barriers are removed and habitat is restored. There’s every reason to believe it will also work here.

Sandra Jacobson, Ph.D. is Director for the South Coast and Sierra Headwaters Region for California Trout. She also manages the South Coast Steelhead Coalition and works with regional partners for Southern California steelhead conservation and recovery. For more information about California Trout visit: https://caltrout.org