For seventy years, a concrete barrier blocked Alameda Creek in California, and the water behind it was widely considered lifeless. In the fall of 2025, work crews finally removed that wall. Within days, two Chinook salmon were swimming upstream through water that had been inaccessible since before the first moon landing.
The fish were not placed there by humans, and no one guided them to the creek. How they found it so quickly remains the most puzzling part of the story.
To understand why two salmon drew the attention of a crowd of biologists, it helps to look at what the creek was before the concrete was poured. For generations, most people in the South Bay area viewed Alameda Creek as a flood control channel, a concrete ditch running behind the back fences of Fremont. Few knew what lay buried beneath the concrete.
Before the channel was built, the creek was reportedly the largest producer of salmon and steelhead trout 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, the river carried large runs of Chinook salmon, steelhead trout, and other fish to the bay and back season after season.
In the 1840s, the area around the creek held so many beavers that explorer Kit Carson was granted the right to trap them. The creek was once a vital, living waterway flowing through what is now one of California’s most developed regions.
Between 1965 and the mid-1970s, work crews converted the lower 12 miles of Alameda Creek into a concrete channel. The goal was straightforward: move water quickly and protect growing suburbs from flooding. In that narrow sense, the project worked. But the concrete walls and flat floor left fish with no places to rest or hide, and nothing grew along the edges. As a living river, the creek became practically dead.
For migrating fish, the channel was a dead end. Salmon and steelhead are born in fresh water, spend years growing in the open ocean, then return to the exact stream where they hatched to spawn. Scientists still do not fully understand how they navigate back, though magnetic fields and a highly sensitive sense of smell are believed to play roles.
Along Alameda Creek, the migratory route was broken at 18 separate points. A single barrier is enough to collapse the cycle, and this creek had many. In California, more than 95 percent of historically used steelhead spawning habitat is either closed off or too degraded. Over the past century, scientists believe more than 20 native steelhead strains in the state have gone extinct.
In the 1970s, the local water agency built a series of rubber dams in a park in central Fremont, about 12 meters upstream. Some men who had grown up fishing for steelhead in that stretch were angry, and a few reportedly threatened violence in protest. The dams were built anyway. The last steelhead seen in the upper creek was in 1967. The creek that once produced more salmon than any place in the South Bay fell silent for a generation.
That silence is what Jeff Miller encountered in the summer of 1997. Miller went for a walk along the creek, starting where it meets the bay and heading inland. For the first 12 miles, he walked beside a narrow waterway inside a concrete channel. Then the creek changed entirely, passing through old quarry lakes, quiet neighborhood parks, and finally into the hills where the water ran freely as it had for thousands of years.
By the time he reached the upper river, Miller had become attached to it. He thought he would bring steelhead back to the creek, and that it would take a few years. It took 28 years. Miller was not new to this kind of struggle. He had spent years in environmental activism, and when steelhead were officially listed as endangered in 1997, he founded a small nonprofit called the Alameda Creek Alliance.
When Miller first attended water agency meetings and asked for the creek to be made suitable for fish, he was reportedly told to leave. He changed his approach. He organized local fishermen and residents to rescue fish trapped in shrinking pools below barriers, making sure it happened in front of television news crews. He also asked the public to send bright postcards to the agencies with a simple message: “I want steelhead back in my creek.”
The pressure was slow and unglamorous, but it gradually changed the culture of the agencies. The creek’s restoration moved from being a nuisance raised at public meetings to a line item in budgets. A multi-agency task force formed, bringing together the San Francisco Public Utilities Commission, the Alameda County Water District, state and federal wildlife agencies, and a growing list of nonprofits.
In 2006, two old dams in Niles Canyon were removed. In 2009, the first of the rubber dams in Fremont came down. In the spring of 2022, crews built a large fish ladder at one of the biggest flood control structures on the creek. One by one, the 18 barriers that closed the creek for decades were removed.
The work was expensive. More than $100 million was spent to reopen this single waterway, with the Alameda County Water District contributing about $80 million of its own funds. Notably, none of the agencies that wrote those large checks had originally prioritized fish rescue. Their mission was water and flood control. The salmon restoration had been gradually integrated into their work.
For years, biologists conducted catch-and-release surveys in the creek to keep an accurate count. Between 2015 and 2023, they caught and released a total of 295 juvenile steelhead, roughly 37 fish per year. Then, in a single year, 2024, they caught and released more than 2,500 juvenile steelhead. It was more than the previous nine years combined. Fifty of the fish tagged that year were later spotted swimming toward the open Pacific, the first such departure in living memory.
One barrier remained. Near Sunol, a natural gas pipeline owned by PG&E ran beneath the creek, and a thick layer of concrete had been placed over it to control erosion. Over time, that layer formed a wall across the channel with an eight-foot drop. For a fish trying to swim upstream, eight feet of vertical concrete was an impassable cliff.
By the summer of 2022, PG&E approached the nonprofit California Trout with an unusual proposal. The pipeline needed long-term protection anyway, so the two organizations decided to solve both problems with one project: move the pipeline and reopen the creek at the same time. Federal funding through NOAA Fisheries brought the budget for this final section to about $15 million. It was PG&E’s first collaboration with conservation groups on such a project.
In the summer of 2025, heavy equipment moved into the creek. Crews relocated the gas pipeline about 30 meters downstream and buried it roughly 6 meters deep. Then they removed the concrete layer that formed the wall. The barrier disappeared within days. Crews then re-graded about 1,800 feet of the creek, shaping a gentle natural slope in place of the sudden drop.
By the fall of 2025, the last barrier on the main stem of Alameda Creek was gone. The response was faster than anyone expected. On November 19, 2025, biological consultants doing routine monitoring spotted two Chinook salmon, between 12 and 24 inches long, holding in the current just upstream of the former wall. They had made their way more than 20 meters upstream from the mouth of the creek within the same week the work was completed.
Claire Buchanan, who led the California Trout project, described the arrival of the two fish as one of the most wonderful feelings, noting that proof of success rarely comes so quickly. Neither fish had ever seen this part of the creek. The last salmon to swim there was lost generations ago, before anyone alive today was born. Yet within days of the concrete being removed, they were entering water their species had been blocked from since before the Apollo missions.
Scientists are quick to add an important caveat. These Chinook salmon likely came from hatcheries elsewhere, wandering into the newly opened creek rather than representing a hidden wild population. But even as strays, they serve a real ecological role. When salmon spawn and die, they carry ocean nutrients into the creek, feeding everything from insects to trees.
The endangered steelhead trout, the fish the entire campaign focused on, are harder to spot. They often travel at night and avoid humans. An electronic antenna installed above the old barrier site had not recorded any tagged adult steelhead as of spring 2026, but the antenna only detects fish that already carry tags. In February 2026, a water agency employee filmed a male and female steelhead using a fish ladder in the lower creek, the first adult steelhead recorded crossing the lower barriers in decades.
The story is not over. Calaveras Dam, a major water supply facility, remains in place, meaning these fish will never reach the last mile of their historical range. Full restoration was never the goal. The goal was to give the fish a chance to survive, and for the first time in 70 years, they have that chance.
The obvious irony is that the concrete poured to control Alameda Creek and make it useful to surrounding residents is the same concrete that choked the creek’s oldest inhabitants. The restoration did not require stocking the creek with fish or transporting salmon from elsewhere. It only required getting out of the way.
Jeff Miller, who started this work in 1997 expecting it to take a few years, is still at it. He and his partners are now working to improve fish survival in the lower flood control channel, restore tidal marsh at the creek’s mouth, and even launch a pilot program to reintroduce beavers to the creek, closing a loop that has been open since Kit Carson’s trappers removed them in the 1840s.
The San Francisco Public Utilities Commission is also preparing to open a watershed center near the creek where visitors can learn about its history. Miller has said that the first time he finds a wild steelhead spawning in the upper creek, he expects to fall to the ground and cry. After 28 years, few who know the story would fault him.
Similar quiet transformations are happening elsewhere. On the Klamath River along the California-Oregon border, four hydroelectric dams were recently removed, the largest dam removal project in American history. Within one year, salmon returned to nearly all of their habitat that had been blocked for over a century. Biologists there described the speed of the return as remarkable.
The lesson from these rivers is that the fish never disappeared. They kept trying, generation after generation, to find a way back. When the barriers finally came down, many returned almost immediately, as if they had been waiting the whole time.
