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Steelhead Get Boost in Alameda Creek Thanks to Restoration Efforts

Steelhead fish passage overhead Alameda Creek

April 24, 2023

Steelhead Get Boost in Alameda Creek Thanks to Restoration Efforts

FREMONT – In a milestone for the re-establishment of a viable steelhead run in the Alameda Creek watershed, high-tech fish monitoring by two local water agencies tagged, detected and documented a juvenile trout this past week, migrating downstream from the upper watershed through lower Alameda Creek toward San Francisco Bay.

For the first time in over 50 years, steelhead, salmon and other anadromous fishes can migrate from the Bay upstream to reach spawning and rearing habitat in the upper Alameda Creek watershed, thanks to the Alameda County Water District and San Francisco Public Utilities Commission’s new fish passage facilities in both the lower creek in Fremont and upper creek in Sunol Regional Wilderness. Within the first two months of the lower ladder’s operation, upstream migrating adult Chinook Salmon and Pacific Lamprey were observed using the new structure to bypass a former barrier known as the BART Weir, with adult steelhead expected to use these ladders as well.

For over 20 years, ACWD, SFPUC, and the Alameda Creek Alliance have been working collaboratively with other stakeholders to address migration barriers and enhance stream flows to allow steelhead to access inland spawning habitat, spawn, and rear in the upper watershed. In October, SFPUC biologists tagged juvenile trout in the upper watershed using Passive Integrated Transponder (PIT) technology. This week, one of those tagged fish was detected 15 miles downstream by specialized antennae located in ACWD’s fish ladder in lower Alameda Creek.

“This epic event of fish passage demonstrates how communities and stakeholders can come together with a united goal of improving such an important resource. It is wonderful to see this positive first sign, and it shows that even in an urban environment we can have natural beauty and functioning ecosystems - right here in our own backyard,” said ACWD Board President Paul Sethy.

“Restoration efforts in complex stream systems like Alameda Creek involve long, painstaking processes,” admitted SFPUC biologist Brian Sak, who added that his agencies’ monitoring program began back in 1998. “We’ve always expected that some of the resident Rainbow Trout in the upper watershed, that have been shown to be directly related to the system’s historic steelhead, make it out to the Bay and ocean when the conditions are just right.  But we have been hoping that reservoir water releases designed to improve spawning and rearing, along with passage improvements, would make things easier for fish. Having confirmation for the first time that trout from upstream are making it downstream to at least Fremont is wonderful news for the countless people that have worked so hard for the shared goal of bringing steelhead back to Alameda Creek.”

“We’ve made incredible progress building fish migration infrastructure in the lower urban portion of our watershed, allowing spawning adult salmon and steelhead to swim upstream to reach good habitat in Niles Canyon and the upper watershed toward Sunol Regional Wilderness,” said Jeff Miller, director of the Alameda Creek Alliance. “But the successful downstream migration of juvenile fish is just as critical; it’s gratifying to be able to document some of our trout moving toward the Bay to complete their dramatic life cycle.”

ACWD’s second fish ladder, completed in December of 2022, was built in cooperation with the Alameda County Flood Control and Water Conservation District. The first fish ladder just upstream was completed in 2019; both ladders were built to provide passage around water supply and flood control infrastructure for steelhead, federally designated as a threatened species, and other migratory fish species of concern, to reach freshwater spawning and rearing habitat in upper Alameda Creek and facilitate the return of juvenile fish downstream to the Bay and ocean. The Lower Alameda Creek Fish Passage Improvements Program is an $80 million investment, with $33 million in grant funding, to address environmental and water supply needs. All told, ACWD has constructed seven fish passage and water supply projects over the past two decades, in cooperation with 24 agencies and stakeholders.

The SFPUC removed Sunol and Niles dams, which were identified as fish passage barriers in Niles Canyon, in 2006. The agency also incorporated Calaveras Reservoir environmental water releases in 2019 and reduced water diversions in 2021 into the Calaveras Dam Replacement and the Alameda Creek Diversion Dam (ACDD) projects. Both are focused on maximizing steelhead spawning and rearing habitat downstream of each facility.  The ACDD project included the construction of a complex fish ladder that incorporates PIT tag technology capable of detecting tagged adult and juvenile fish moving upstream and/or downstream through the ladder.  The SFPUC conducts a variety of annual monitoring projects designed to document Rainbow Trout and steelhead spawning, rearing and downstream movements, fish population and community characteristics, and water quality conditions in portions of the upper watershed above and below its facilities.


Since steelhead in the Bay Area were listed as a threatened species under the Endangered Species Act in 1997, a consortium of organizations and agencies has cooperated on restoration projects to allow migratory fish to reach spawning and rearing habitat in upper Alameda Creek. Partners in the Alameda Creek Fisheries Restoration Workgroup have completed nearly two dozen fish passage projects in the watershed since 2001, including removing small dams and other fish passage barriers, construction of fish ladders, replacement of road culverts, and installation of fish screens at water diversions. Water agencies are also working on projects to improve stream flows and restore stream and riparian habitats along Alameda Creek and its tributaries. These restoration projects now make up to 20 miles of potential spawning and rearing habitat in Alameda Creek and its tributaries accessible to ocean-run salmonids.

Steelhead, salmon and some lamprey are anadromous fishes, living out their adult lives in the ocean and migrating up freshwater streams and rivers to spawn, with their young rearing in suitable habitat when available. Resident Rainbow Trout and steelhead are different life forms of the same species, Oncorhynchus mykiss - rainbows remain in a stream environment throughout their lives, while steelhead migrate to the ocean and return to their natal stream to spawn.