The Alameda Creek watershed in California is showing signs of recovery, with improved water quality linked to the return of trout and salmon. A concrete barrier that had blocked the creek for seventy years was removed in the fall of 2025, and within days, two chinook salmon were observed swimming upstream through waters that had been inaccessible since before the first moon landing.

To understand the significance of that event, it helps to know the creek’s history. Before it was lined with concrete, Alameda Creek was the most productive salmon and steelhead trout stream in the entire San Francisco estuary. Its watershed covers roughly 700 square miles, making it the largest tributary feeding the bay. For thousands of years, it carried large runs of chinook salmon, steelhead, and other fish between the ocean and their spawning grounds.

Between 1965 and the mid-1970s, crews converted the lower 12 miles of the creek into a concrete flood-control channel. The project succeeded at moving water quickly and protecting growing suburbs from flooding, but it made the creek nearly uninhabitable for fish. A series of additional barriers, including rubber dams built in the 1970s and a concrete apron installed to protect a natural gas pipeline, further blocked migration routes. At one point, fish passage was interrupted at 18 separate locations along the creek.

The last steelhead trout seen in the upper creek was recorded in 1967. For decades, the channel remained largely empty of returning fish.

In the summer of 1997, Jeff Miller, a longtime environmental activist, walked the creek from the bay to its headwaters and became committed to restoring it. He founded a small nonprofit called the Alameda Creek Alliance that same year, when steelhead trout were listed under the Endangered Species Act. Miller expected the effort to take a few years. It took 28.

His campaign relied on steady public pressure. He organized local anglers and residents to rescue fish trapped in shrinking pools below barriers, often in front of television news cameras. He also asked residents to send bright postcards to water agencies carrying a simple message: they wanted steelhead trout back in the creek.

That pressure gradually changed the culture of the agencies involved. Over time, a multi-agency working group formed, including the San Francisco Public Utilities Commission, the Alameda County Water District, state and federal wildlife agencies, and several nonprofits. Together, they coordinated the removal of barriers one by one. The first two old dams were removed in Niles Canyon in 2006. A rubber dam in Fremont followed in 2009. A large fish ladder was completed in 2022. More than $100 million was spent reopening the creek, including roughly $80 million from the Alameda County Water District alone.

For years, biologists conducted catch-and-release surveys to track juvenile steelhead in the creek. Between 2015 and 2023, they caught and released an average of 37 fish per year. In 2024 alone, they caught more than 2,500 juvenile steelhead. Fifty fish tagged that year were later observed heading toward the bay, the first such migration in living memory.

One major obstacle remained. Near Sunol, a PG&E natural gas pipeline crossed beneath the creek. A thick concrete erosion-control layer had been placed over the pipeline years earlier, hardening into a vertical wall with an eight-foot drop that fish could not climb. In 2022, PG&E approached the nonprofit California Trout with an unusual proposal. The pipeline needed long-term protection anyway, so the two organizations agreed to solve both problems in a single project. The pipeline was relocated roughly 30 meters downstream and buried about 6 meters deep, and the concrete barrier was removed. Crews then reshaped about 1,800 feet of the creek into a natural, gradual slope.

The work was completed in the fall of 2025, funded in part by several million dollars in federal money through NOAA Fisheries. The final phase cost about $15 million.

On November 19, 2025, two chinook salmon, roughly 12 to 24 inches long, were observed holding in the current just upstream of the former barrier site. They had traveled more than 20 miles from the bay. Claire Buchanan, who led the California Trout project, described the timing as remarkable, noting that proof of success that quickly is rare in restoration work.

Biologists noted that the two fish were likely hatchery-raised rather than a hidden wild population. Even so, their arrival demonstrated the central premise of the restoration effort: once barriers are removed, salmon can find their way back. They also bring marine nutrients into the creek when they spawn and die, feeding the broader ecosystem.

Steelhead trout, the species the campaign was built around, are harder to track. They often migrate at night and avoid people. An electronic antenna installed above the old barrier site had not detected tagged adult steelhead as of spring 2026, but it only detects fish already carrying tags. In February 2026, a water district employee filmed a male and female steelhead using a fish ladder in the lower creek, the first documented adult steelhead passing the lower barriers in decades.

Full restoration was never the goal. Calaveras Dam, a major water-supply facility, remains in place, meaning fish will never reach the last mile of their historical range. The objective was to give the fish a chance to survive, and for the first time in seventy years, that chance exists.

Miller continues to work on related projects, including improving survival in the lower flood-control channel, restoring tidal marsh at the creek’s mouth, and exploring a pilot program to reintroduce beavers to Alameda Creek. Those animals had been heavily trapped in the area since the 1840s.

Similar restoration work is happening elsewhere. On the Klamath River along the California-Oregon border, four hydropower dams were removed in the largest dam-removal project in American history. Within a year, salmon returned to nearly all of their historical habitat there.

The experience at Alameda Creek and other rivers suggests that fish populations did not disappear when their habitats were blocked. They waited, generation after generation, until the path was reopened. When it was, they began to return almost immediately.