Putah Creek, a waterway in California that was once severely degraded by human intervention, is now experiencing a remarkable resurgence of its iconic salmon population. For many years, the creek’s natural flows were disrupted and its ecosystem harmed by extensive damming and water diversions. However, a concerted effort to restore the creek to a semblance of its natural state has yielded unexpected and abundant returns of chinook salmon, far exceeding initial expectations and serving as a powerful indicator of aquatic health. While the recent, large-scale removal of four dams on the Klamath River has garnered significant attention, the success story unfolding on Putah Creek, though less celebrated, is equally compelling.

The 85-mile-long Putah Creek, originating in the Mayacamas Mountains, transforms from a narrow, boulder-strewn stream into a broader channel as it approaches the Sacramento River floodplain. Throughout its course, it has been historically confined by dams, channeled through irrigation ditches, and constrained by artificially straightened and hardened banks. These modifications effectively imprisoned the creek, leading to the disappearance of its native salmon population for decades. Yet, in 2025, a startling event occurred: over 2,000 chinook salmon returned to spawn in Putah Creek, a triumph attributed to both dedicated human-led restoration initiatives and the inherent resilience of the fish themselves.

"It’s the ‘Field of Dreams’ thing: ‘If you build it, they will come’," remarked Andrew Rypel, a fish ecologist who formerly held a position at the University of California, Davis, and is now with Auburn University. "With science, with community, you can do some really special things." This sentiment underscores the collaborative and scientifically informed approach that has driven the creek’s recovery.

The history of Putah Creek tragically mirrors the broader narrative of how rivers in California’s Central Valley, a region renowned for its agricultural productivity, have been subjected to extensive and often detrimental water infrastructure projects. This area has been described by author Joan Didion as "plumbing on the grand scale." In 1957, the Bureau of Reclamation constructed the Monticello Dam and the Putah Diversion Dam, creating Lake Berryessa to impound water for agricultural and urban needs. Consequently, the creek’s diminished flows became too warm to sustain salmon and other native fish species, which were subsequently displaced by invasive, heat-tolerant species like bass. The situation reached a crisis point in 1989 and 1990 when the lower reaches of Putah Creek completely dried up, leaving behind countless dead fish. The then-city manager of Davis, through which the creek flows, lamented that "the wildlife’s severely stressed, dying, or dead."

However, this period of ecological devastation sowed the seeds for Putah Creek’s eventual revitalization. In 1990, the Putah Creek Council, an environmental advocacy group, initiated legal action against the Solano County agencies responsible for managing the dams. Joined later by the city of Davis and U.C. Davis, their argument centered on the principle that California law mandates dam managers to maintain fish populations in good condition. This legal battle culminated in a landmark settlement in 2000 known as the Putah Creek Accord. This agreement compelled water managers to release flows that more closely mimicked natural patterns, ensuring the creek would no longer dry up during summer months and incorporating spring pulses to stimulate fish breeding. A crucial element of the accord was the introduction of a fall surge of water, termed an "attraction flow," designed to entice salmon to return.

"It was a speculative, ‘Well, maybe this is going to work’ kind of thing," explained Phil Stevens, executive director of the Putah Creek Council. "Nobody knew whether the salmon would come or not." This uncertainty highlights the pioneering nature of the restoration efforts.

Despite the accord, the volume of water released remained modest, with approximately 95% of Putah Creek’s water still allocated for human consumption. Nevertheless, even this limited return of natural flow, supplemented by other restoration activities such as riparian plantings and community clean-up events, proved remarkably effective. By 2012, scientific assessments confirmed that native fish, including Sacramento suckers and tule perch, had already "regained dominance." The following year, eight chinook salmon, drawn by the attraction flows, navigated into Putah Creek—the first recorded instance of this occurring in decades. The subsequent year saw several hundred salmon arrive, and by 2016, the number had climbed to around 1,500. This improbable recovery prompted conservation groups to establish a Salmon Fest in the town of Winters, an event that would have been unimaginable just years prior. Christine Parisek, a postdoctoral scholar at U.C. Davis’s Center for Watershed Sciences, noted that this astonishing comeback demonstrates "it’s possible to recover the ecology of a system" by reinstating natural flows, even if it requires patience and a long-term commitment. The simple, yet profound, realization was that fish, in essence, just needed water.

As the salmon began to return to Putah Creek, a critical question emerged: from where were these fish originating? Salmon are famously known for their instinctual journey back to their natal streams to spawn. However, given Putah Creek’s extended absence of chinook, the initial returning fish were clearly "strays" from other locations. This mystery was unraveled in 2020 when Rypel and his colleagues discovered that the vast majority of the newly arriving salmon were actually products of Central Valley fish hatcheries. During dry years, these fish were transported by truck to the San Francisco Estuary. This artificial early life in a non-natal environment resulted in a poorly developed imprinting on their true home waters. Consequently, as adults, they entered the Sacramento River and inadvertently navigated into the Toe Drain, a warm, channelized ditch that ultimately led them to Putah Creek. While the tendency of hatchery-raised salmon to deviate from their birth rivers is generally viewed as undesirable, as it can dilute the gene pools of wild populations, in the case of Putah Creek, there were no wild fish to be compromised. "If you do the hard habitat work, the hatchery fish can help you," Rypel stated, highlighting how these displaced hatchery fish, under improved conditions, played a crucial role in re-establishing a population.

Further scientific investigation yielded even more remarkable findings. In a 2025 study, Rypel and his team analyzed otoliths—small, calcium carbonate structures found in the inner ear of fish that record growth and elemental signatures of their environment. By examining these otoliths from Putah Creek chinook, researchers could determine the specific waters where individual salmon spent their lives. The analysis revealed that a portion of the returning fish had not originated from hatcheries at all. Instead, they had been born in Putah Creek itself, migrated to the ocean, and subsequently returned as adults, completing the entire natural life cycle. This indicated that the accidental chinook population in Putah Creek was beginning to shed its domestic origins and truly rewild.

The broader context of salmon populations in the Central Valley is one of severe decline. Dams, water diversions, prolonged drought, and numerous other stressors have placed immense pressure on these species, with projections suggesting they may face extirpation or minimal abundance by the end of the century. Putah Creek stands out as one of the few streams where salmon runs are currently experiencing growth rather than shrinkage. "You can go ahead and pooh-pooh the hatchery fish, but it’s all hands on deck," emphasized Max Stevenson, Putah Creek’s streamkeeper, a position established by the accord and funded by the Solano County Water Agency, underscoring the inclusive approach to recovery.

Despite these significant advancements, Putah Creek continues to face substantial challenges. In many sections, the creek bed is compacted or covered by silt, hindering the formation of ideal spawning grounds. While Stevenson has undertaken efforts to improve this by breaking up existing gravel with heavy machinery and importing additional gravel, the task remains incomplete. A more pressing obstacle is a 10-foot-high check dam that impedes salmon migration until late fall, coinciding with the end of the irrigation season. Only when water managers remove wooden boards do chinook gain passage upstream—an archaic method of fish passage. In 2021, torrential rains led to a massive influx of organic matter into the creek, causing low-oxygen conditions that killed incoming salmon before the check dam was opened, effectively wiping out nearly an entire year’s spawning effort. Stevenson is actively pursuing solutions, including the construction of a bypass channel or an underwater fish ladder to facilitate salmon passage over the dam, or even upgrading irrigation infrastructure to allow for the dam’s complete removal.

The successful restoration of salmon in such a fundamentally altered environment, according to Rypel, represents a form of "reconciliation ecology"—the practice of creating space for nature within landscapes profoundly reshaped by human activity. The chinook salmon of the Central Valley are often raised in flooded rice fields, navigate irrigation ditches, and spawn in artificially supplied gravel. These modified conditions may well represent the future of salmon in an Anthropocene California, a region extensively re-engineered by human endeavors, yet still capable of supporting aquatic life if given the opportunity. As Stevenson aptly put it, "We can build cities, we can make factories, we can go to the moon. We can make a salmon run here if we want one." This sentiment encapsulates the power of human intention and action in fostering ecological recovery.