Among members of the salmon family, the Southern California Steelhead (Oncorhynchus mykiss), or simply steelhead, is the only species for which a thriving population was commonly found in coastal waters and within watersheds of Southern California, from Point Sal south to the U.S./Mexico border. Throughout this coastal region, large numbers of adult steelhead historically swam from the ocean into rivers and streams between winter and spring to migrate further upstream through coastal watersheds, including the Los Angeles River Watershed (LARW), and spawn in upper reaches of mountainous tributaries. After rearing in freshwater systems, juvenile steelhead reached maturity and many of them were able to migrate back to the ocean to complete the life cycle.

But in the early 20th century, the Southern California Steelhead population started to decrease abruptly due to the negative impacts of overfishing and urbanization, including constructions of dams, flood control structures, and other man-made barriers that precluded the natural passage of fish and their upstream (adults) and downstream (juveniles) migrations throughout urban coastal watersheds. The population abundance plummeted to such low numbers that the Southern California Steelhead Distinct Population Segment (DPS) has been listed in the federal Endangered Species Act (ESA) since 1997.

Similarly, steelhead was a common species in the LARW until the 1940s, before the population drastically decreased due to the impact of excessive recreational fishing pressure and the presence of man-made physical structures and barriers, in both the Los Angeles River mainstem and some of the upper tributaries. However, some of these upper tributaries are still home to isolated populations of rainbow trout, which is the non-anadromous life history form of O. mykiss. These populations can interbreed with steelhead, and either of these two life history forms can produce offspring that exhibit the alternate form (i.e., resident rainbow trout can produce anadromous progeny and vice-versa). Some of these rainbow trout populations are considered relicts of native coastal steelhead lineage that have adopted a resident life history in freshwater systems, with juveniles that cannot migrate back to the ocean and adults that complete their life cycle in freshwater.

The LARW is considered an important region to support the viability of the remaining populations of Southern California Steelhead due to its key role in potentially maintaining resident rainbow trout populations of coastal steelhead lineage in its upper tributaries. In fact, recommended recovery actions for the LARW listed in the NMFS Southern California Steelhead Recovery Plan, issued in 2012, include habitat restoration, remediation of passage barriers, and other actions that address major stressors and limiting factors for the Southern California Steelhead DPS.

The main objective of the LAR FPHS and the LAR FPR Projects, combined, is to conduct science-based research and design (Basis of Design Report to 60% design drawings, CEQA, and initial permitting) of fish passage and habitat structures that address limiting factors for steelhead and other native fish within a 4.8-mile section of the concrete-lined Los Angeles River through Downtown Los Angeles. This pilot effort provides opportunities to address watershed-wide data gaps. In turn, this information can be used to fill these gaps and to support future projects aimed to enhance steelhead recovery throughout the LARW, and to identify other potential suitable sites for fish passage projects across the Los Angeles River and its upper tributaries.

The LAR FPHS Project started in January 2020, while the associated LAR FPR Project started in June 2021 to supplement the design phase of the LAR FPHS Project. Both of these Projects are planned for completion in December 2021.

Why are we doing this project?

The Council for Watershed Health (CWH) and Stillwater Sciences are leading the LAR FPHS and LAR FPR Projects in partnership with the City of Los Angeles, who is the lead agency, as well as Reclamation, SCCWRP, NMFS, USACE, the County of Los Angeles, CDFW, USFWS, RWQCB, ASF, and FoLAR. The city has adopted sustainability and biodiversity plans to bring back native species, including steelhead and other native fish among many other species, with an ultimate goal of improving connections between people and nature. These two projects, in combination, are intended to create steelhead fish passage in the Los Angeles River as a migration corridor to the upper tributaries of the LARW spawning grounds. This pilot effort can be replicated in other concrete-lined channels to provide fish passage and habitat structures for migrating fish. Watershed scientists are working to address study questions focused on watershed-wide limiting factors to steelhead recovery. These two Projects provide an opportunity to align with related USACE, City and County restoration projects, scientific studies, and ongoing watershed and Los Angeles River monitoring plans and efforts. These include, but are not limited to, the following project objectives:

1. To implement key features of the Congressionally Authorized L.A. River Ecosystem Restoration Project, Alternative 20 Integrated Feasibility Report, also known as the Area with Restoration Benefits and Opportunities for Revitalization (ARBOR) reach.

2. To implement conceptual USACE Arroyo Seco Ecosystem Restoration Watershed Study recommendations of fish passage, barrier removal, stream naturalization, and fish habitat improvements to support multiple life stages of rainbow and steelhead trout and re-establishment of resident trout populations.

3. To improve conditions for other native fish in the LARW and upper tributaries, including Santa Ana sucker, arroyo chub, unarmored three-spine stickleback, speckled dace, Pacific lamprey, and other aquatic species and wildlife.

4. To implement adopted plans, policies, and recommendations of federal, state, regional, and local agencies, including NMFS’s Southern Steelhead Recovery Plan, City of L.A.’s L.A. River Revitalization Master Plan, Greater L.A. River Integrated Regional Water Management Plan, County L.A. River Master Plan, L.A. Mayor’s Sustainability Plan, L.A. Biodiversity Plan, and others.

5. To enhance ecological connectivity between in- and off-channel areas to maximize the urban biodiversity and ecosystem benefits (environmental and socio-economic) of the project.

Will we really see steelhead in the LA River again?

Yes. If effective fish passage design and conditions are implemented, steelhead will be able to migrate to upper tributaries of the LARW and ultimately complete their life cycle. Steelhead thrive in cool, clean, well-oxygenated water. The LARW’s water quality, temperature, vegetation (providing shade and natural cleansing of flows), and stream conditions (e.g., dissolved oxygen levels, velocity, sediment load, etc.) will need to improve to support total maximum daily loads (TMDLs), water quality thresholds set by the RWQCB under the Clean Water Act, as well as steelhead suitability requirements. A healthy riverine and aquatic ecosystem in the Los Angeles River will address the needs of both fish populations and local communities. Many Angelenos have expressed interest in a clean LA River, with prospects of recreation and enjoyment. By meeting the needs of native fish species in the LA River, this pilot effort promotes species recovery as a top priority, with numerous multiple benefits for Angelenos in perpetuity.

Cost

How is the “project design” being funded?

The Wildlife Conservation Board has funded the LAR FPHS Project under a State of California Prop. 68 Fish Passage grant in the amount of $1.356M. In June 2021, the Santa Monica Mountains Conservancy funded the LAR FPR Project under the State of California Prop. 1 for a total amount of $300,000. The City and other partners, including Stillwater Sciences, SCCWRP, ASF, and FoLAR, are providing in-kind services as matching funds for the two Projects. Future phases of these two Projects will include 100% design, permitting, and construction.

How will “implementation” of the project be funded?

The full cost to implement these two Projects has not yet been determined. The Projects' proponents will work with the associated agencies and additional partners to identify funding to fully implement the effort.

Who is responsible for operations and maintenance?

This pilot effort is being designed to be self-cleaning by mimicking natural stream morphology, with natural flushing of sediment by hydraulic processes. Habitat structures would be anchored in place to maintain channel stability and protection of existing infrastructure. Flood-related requirements must be met in order for the project to be constructed. The City, County, and USACE are discussing operations and maintenance roles and responsibilities for this effort. Maintenance responsibilities would be similar to what they are now, which is minimal in this concrete-lined reach of the channel. However, future project maintenance costs, if any, would be funded through a cooperative agreement with the Projects' partners.

Monitoring

What type of monitoring is required?

Monitoring includes assessment of structural stability of the structures, biological surveys (specific to steelhead and other native fish as well as invasive species), and physical habitat conditions.

Water Supply Priorities

Do the Projects impact water supplies?

No. The LAR FPHS Project and the LAR FPR Project are consistent with the California State Water Resources Control Board (SWRCB)’s LA River Environmental Flows Study (EFS) that is currently underway. As the Projects' partner, SCCWRP is working on the modeling and steelhead/rainbow trout species criteria for the Los Angeles River in collaboration with Stillwater Sciences. Steelhead are one of many target species considered in SCCWRP’s hydrologic and hydraulic modeling for the Los Angeles River. Since the LAR FPHS and the LAR FPR Projects are focused on migratory periods, meaning when adult steelhead move at the tail-end of a winter storm, no additional water is needed to support migration. The LA Department of Water and Power, among other water utilities, is involved in the study to address integrated water management objectives (water quality, water reuse, recycling, and other water supply/management objectives). The design does consider low-flow conditions for fish to move upstream and downstream. These flows are also consistent with the SWRCB LA River EFS.

How fast do steelhead swim?

Migration rates reported for adult steelhead in rivers are highly variable, ranging from less than 0.6 miles per day (mi/d) to more than 25 mi/d (Keefer et al. 2004, Salinger and Anderson 2006, English et al. 2006, Jepsen et al. 2012). In the absence of data on Southern California Steelhead behavior, migration rates for steelhead in the Los Angeles River are assumed to be similar to those of steelhead migrating in naturally flowing rivers, like those measured in British Columbia, Canada (English et al. 2006). For such rivers, steelhead migration rate averaged 7.3 mi/d. Based on this average migration rate, when applied to adult steelhead in the Los Angeles River, it is expected that adult steelhead would take 2.7 days on average to reach the Projects' reach 20 miles (mi) upstream from the ocean and four days to reach perennial habitat in the central Arroyo Seco 30.5 mi upstream from the ocean. It remains uncertain whether the duration of a typical storm flow event is long enough for steelhead to reach these locations in a single event, or if multiple storm events are needed.

• Recovering Steelhead Trout Populations in the L.A. River Watershed [ArcGIS StoryMap]

• Project Profile [PDF]

• Q&A Fact Sheet [PDF]

• Final Techical Memorandum: Conceptual Ecological Model and Limiting Factors Analysis for Steelhead in the Los Angeles River Watershed, September 2020

• LAR FPHS - Basis Of Design Report (30% Design) [PDF]

• LAR FPHS - Appendices to 30% Basis Of Design Report [PDF]

• LAR FPHS - Basis of Design Report (60% Design) [PDF]

For more information please reach out to the Los Angeles River Fish Passage Project Manager, Andrea Dell’Apa adellapa@watersheadhealth.org or 213-229-9945 - ext.5.