The endangered coho salmon have been on a steady decline as urbanization wreaks havoc on their remaining natural habitat. But the recent demolition of an old dam and fish ladder on the former San Geronimo Valley golf course has freed up one of their important breeding passages.

One of the more unspoken side effects of unbridled construction is not only how it can level once towering tree groves, but how laying concrete and making of man-made lakes can derail spawning routes for migratory fish. In fact, 27 regional salmon runs are now either endangered or threatened by encroaching human activity. (Salmon, specifically, are one of the most relied-upon food sources for large predators like brown and black bears, wolves, and birds of prey.) These fish key players in safeguarding the biodiversity in the areas they spawn at and migrate to – which is why Friday's clearing of a 100-year-old dam along Marin County's San Geronimo creek is so necessary.

"There is so much impressive work that goes into creating a whole new environment designed to benefit both the environment and the community,” said Director of Watershed Conservation Preston Brown in a news release, citing that there's "more work ahead" as the Salmon Protection and Watershed Network (SPAWN) continues restoring some five-acres of previously destroyed floodplain habitat. “Knowing there is no fish barrier after so many years is exciting, and we are grateful to all of the organizations and individuals who are working on and supporting this long-awaited project.”

The 20-year-old Roy's Pools, a former fish ladder, before it was removed. (Courtesy of SPAWN)

By removing the dam and fish ladder, a free-flowing 250-feet long creek channel was created to create critical habitat for young salmon; SPAWN's still-continuing project, Roy’s Pools Fish Passage and Floodplain Restoration Project, will also create valuable habitat for terrestrial wildlife and increase the number of trees for nesting birds. A new 100-foot pedestrian bridge was also fitted this past Friday that links to different trailheads and provides safe fish viewing over a wider, more complex (and now stable) creek channel.

“Everything looks amazing, from water flowing through the site to willow stakes sprouting,” said biologist Ayano Hayes, who continues to help overlook the project, in the release. “The next part of the project will be completed next summer and involves creating a side channel, inset floodplains, and an enlarged riparian forest that will provide winter refuge and additional feeding habitat for juvenile salmon.”

SPAWN is currently planting "trees, grasses, shrubs, and other native plants" found in the area that will help create a more systemic environment for the area's wildlife.

The coho salmon (Oncorhynchus kisutch) remains one of the rarest salmon species anywhere in the world after being deemed an endangered species in 1996, with the population in Marin among the strongest remaining in California — and critical to the recovery of the species.

You can read more about the restoration project here.

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Image: Coho salmon, courtesy of Getty Images via mlharing