Coho Salmon Show Signs of Recovery in San Geronimo Valley Tributaries — But the Fight Isn’t Over

For a species teetering on the edge of extinction, every fish counts. That’s the takeaway from this year’s spawning survey in San Geronimo Valley, where SPAWN documented a modest but meaningful uptick in returning coho salmon in San Geronimo tributaries — a sign of hope for a population that has spent decades fighting for survival.

What the Survey Found

The Salmon Protection And Watershed Network (SPAWN) has released its 2026 spawning survey report, covering six tributaries of San Geronimo Creek. Over roughly 3.4 miles of stream, surveyors counted:

• 28 coho redds (nests) and 4 steelhead redds, found in five of the six creeks surveyed
• 30 live coho salmon and 4 live steelhead trout observed directly

Redd counts by creek:

• Arroyo Creek: 12 coho redds, 2 steelhead redds — the most of any tributary
• Woodacre Creek: strong coho numbers, but no steelhead redds this year
• Montezuma Creek: 7 coho redds
• North Fork San Geronimo: 2 coho redds
• Larsen Creek: 1 coho redd
• Willis Evans Creek: no salmonids observed

It’s a small area doing outsized work. San Geronimo Creek’s sub-watershed makes up only about 9 percent of the 103-square-mile Lagunitas Creek Watershed, and the tributaries only a fraction of that– yet in strong years its tributaries have supported as much as half the spawning population within the San Geronimo sub-watershed — and up to 30 percent of all coho redds across the entire Lagunitas Creek Watershed.

A Reason for Hope, Not Complacency

“This year’s survey provides a reason for hope, but not complacency,” said Todd Steiner, founder of SPAWN. “Every returning coho is a remarkable achievement given how perilous their survival remains. The San Geronimo tributaries are small streams, but they can support a remarkably large share of the salmon returning to the Lagunitas Creek watershed. Protecting and restoring these streams is essential to giving coho salmon a future.”

Because coho salmon live for three years and die after spawning, each run represents a distinct “year class.” According to SPAWN, all three year classes have trended upward since the region pulled out of a two-year drought spanning 2018–19 and 2019–20 — a hopeful signal, even if the numbers remain far from historic norms. This year’s spawning run is still well below the strongest showing for this year class, recorded in 2004–05 at 110 fish, and almost certainly a fraction of population levels before coho were listed as an endangered species.

SPAWN is thankful for the majority of Creekside landowners who allow SPAWN onto their property to do the spawning counts.

The Culvert Problem

Much of the story here comes down to infrastructure. Rainfall timing and volume heavily influence spawning success in the tributaries because of undersized road culverts that act as barriers to fish passage. These culverts are often impassable except during brief windows right after significant storms, when water levels happen to be just right for coho to squeeze through. Miss that window, and the fish simply can’t reach the upstream habitat they need to spawn.

That dynamic helps explain this year’s pattern. “It’s not surprising that the highest spawning numbers are in Arroyo and Woodacre Creek, as old culverts have either been replaced or modified into more fish-friendly designs that do not restrict access,” Steiner said. “What is surprising is the tenacity and athletic ability of coho to jump through and swim through the culverts on Montezuma and Larsen Creeks, despite culvert obstacles.”

Habitat loss compounds the problem. Steiner noted that roughly 50 percent of historic spawning habitat has already been eliminated by Marin Municipal Water District dams, making it even more critical to open up and restore what remains in San Geronimo Valley. Without that, coho remain far from the population levels needed to be considered recovered and removed from the state and federal endangered species lists.

A Call to Action

SPAWN’s leadership is now pressing Marin County to reinvest in fixing the remaining barriers. “We urge Marin County to revitalize the San Geronimo culvert replacement program, which started strong with a few good years and appears to have gone dormant about a decade ago, and ensure the Stream Conservation Ordinance is enforced,” said Ken Bouley, executive director of Turtle Island Restoration Network.

Bouley also noted the Stream Conservation Ordinance, passed four years, ago needs to be strictly enforced by the County.

Unfortunately, the overall coho spawning numbers for the Lagunitas Watershed as a whole did not show an increase from three years ago low, diminishing the good news SPAWN found this year in San Geronimo tributaries.

The message from this year’s survey is a familiar one for endangered species recovery: progress is possible, but it’s fragile, and it depends on sustained investment — in this case, in fixing the culverts that stand between coho salmon and the streams they need to survive.

By Sierra LeTourneau, SPAWN Salmonid Monitoring Intern

Header photo of a happy SPAWN Nursery-grown lupine at Chicken Ranch Beach in Tomales Bay, California.

In honor of Endangered Species day, which was this month on May 17th, we wanted to highlight the work SPAWN has done to improve populations for some of California’s listed Endangered Species.

SPAWN as a program seeks to support the endangered Central California Coho populations. Through almost 30 years of monitoring, habitat restoration, and litigation. SPAWN has sought to improve the Coho population in the Lagunitas Creek Watershed.

Recently, SPAWN has been contributing to the restoration of Chicken Ranch Beach as part of the Tomales Bay Foundation’s initiative to improve the water quality and habitat at CRB. This project seeks to provide habitat for a few more of California’s listed endangered species. This includes the tidewater goby, California red-legged frog and the western pond turtle. 

The tidewater goby (Eucyclogobius newberryi), is a small fish that lives in brackish waters, areas that are a confluence of freshwater and saltwater. Tidewater gobies rarely exceed 2 inches in size. Historically they were found in over 150 lagoons and estuaries in California, in 1994 due to massive habitat loss and disruption the tidewater goby was listed as an endangered species. Tidewater gobies prefer submerged and emergent aquatic vegetation, for foraging and juvenile rearing, which is included as part of the CRB restoration efforts. 

The California red-legged frog (Rana draytonii) , another well-known endangered species, was also in mind during the planning for the restoration at CRB. Since 1996, The California red-legged frog (CRLF) has been listed as an endangered species. Much like the Tidewater goby, their status is a reflection of depleted habitat and resources as a result of anthropogenic development. CRLF needs habitat for aquatic breeding, aquatic non-breeding habitat for juvenile and adult dispersal and predator avoidance, and upland riparian habitat adjacent to the aforementioned aquatic habitat. CRLF are more sensitive to changes in salinity than tidewater gobies, planning for both of their needs overlaps significantly in the CRB restoration plan.

Lastly, the western pond turtle (Actinemys marmorata) is not currently listed as an endangered species in the state of California but rather a species of special concern. They were also included in the CRB planning efforts. Their populations have dwindled as a result of disease and habitat destruction, and predator introduction. Elements in the CRB planning for the western pond turtle habitat include submerged longs, large rocks, and muddy banks. 

As of May 2026, we have been working on weeding at the site and implementing irrigation to keep the plants watered as we get closer to the start of summer. Volunteer days at Chicken Ranch Beach remain on alternating Wednesdays and Saturdays, please check the schedule and stop on by to help out!

Nicasio Reservoir Expansion: Will the Town of Nicasio and Coho Salmon Be Shafted by MMWD Again?

By Todd Steiner, Founder and Special Projects Director and Ken Bouley, Executive Director

Get more info on this topic at: https://www.nicasio.net/flood

On June 26^th, Marin Water attended a public hearing at Nicasio School to discuss the Nicasio Reservoir Expansion, a plan to increase the capacity by 3,700 acre feet by installing a 280-foot-long, 4.4-foot-high inflatable rubber gate spanning the spillway crest.

Board members Khush and Samson were confronted by an alarmed community, worried that the proposal would exacerbate flooding in their town, including the school, where the meeting was held, and require the taking of property by eminent domain.

We found the mistrust well-founded, a feeling reinforced by inadequate responses on whether the project would inundate the school’s septic system, playground, and the building itself, while impacting private lands and other community infrastructure.

Nor was there an explanation of why the water district, decades ago, discontinued maintenance of Nicasio and Halleck Creeks, which feed the reservoir and once supported large runs of endangered coho. These creeks are now choked with sediment caused by the dam.

When SPAWN staff asked Marin Water to agree to restore these creeks, as a demonstration of community good will, Director Khush failed to do so, excusing MMWDs malfeasance by blaming the need for yet more studies and regulatory red tape for his inability to take responsibility. While it is true permits are required, permitting for restoration activities (as opposed to permits to destroy habitat) is not a real hurdle. His response was met by community derision.

In addition to harvesting local water by raising the dam height, Marin Water failed to address the issue that it plans to use Sonoma County water from the Russian River to fill the Nicasio Reservoir during drought years, through a separate proposed pumping plant and a 36-inch-wide pipeline running 13.2 miles from the North Marin Aqueduct.

MMWD describes this $1.25 million funded plan as “the District’s largest water supply resiliency project in 40 years,” including more than doubling its current proposed size, stating, “Potential future phases of this project could increase replenishment of stored water to up to 8,100 acre-feet.” Is the future plan to completely inundate Nicasio with this more than doubling water storage?

The nearby Lagunitas watershed is critical to restoration of the coho salmon throughout Central California, providing more than 20% of the current population, and providing a source of restoration broodstock. That is why tens of millions of tax-payer dollars have already been invested in Lagunitas coho recovery, and even larger expenditures in the Russian River watershed. Further damage to the population caused by Nicasio reservoir expansion and taking more water from coho salmon in the Russian River watershed will certainly thwart coho recovery.

What was not stressed at the meeting was conservation. According to the New York Times, Los Angeles’ population has increased 15% from 3.4 million to 3.9 million people since 1990, yet its total water use has decreased by 33%.

Marin Water should follow suit by spending out tax-payer dollars studying what LA has accomplished and invest heavily on conservation efforts. It should also commit to creating a fish bypass around Nicasio Reservoir to restore endangered coho salmon in Nicasio and Halleck Creek habitat. The federal Coho Recovery plan calls for them to “evaluate alternatives/feasibility to provide passage over Seeger Dam (Nicasio Reservoir)”. As far as we know, this has never happened.

The demise of Lagunitas run of coho salmon is a direct result of Marin Water’s prior actions. Seeger Dam, which created Nicasio Reservoir, eliminated nearly 16 miles of coho habitat, and a similar impact was brought by the construction of Peters Dam to create Kent Lake. We are in an extinction crisis. Marin Water has a moral and legal obligation to restore this habitat.

We call on MMWD to:

• Commit to nixing the Nicasio Reservoir expansion and causing distress and harm to Nicasio residents.
• Secure water resiliency for Marin while making conservation the priority.
• Commit to creating a fish bypass around Nicasio Reservoir to restore endangered coho salmon and Nicaiso and Halleck Creek habitat.

To take action and get more info: https://www.nicasio.net/flood

For Immediate Release, May 19, 2025

Contact: Ayano Hayes, Watershed Conservation Manager, ahayes@tirn.net

Habitat Restoration Field Showcase (New Date!): Sediment Load Reduction Project in the Lagunitas Creek Watershed

MARIN COUNTY, CA — On Wednesday, May 28 from 9:00am-1:00pm, join SPAWN and Pacific Watershed Associates (PWA) for an exclusive Field Showcase following the first winter of the Sediment Load Reduction Project in the Lagunitas Creek Watershed. This is your chance to see environmental restoration up close and learn directly from the experts behind it.

We’ll kick things off with a brief presentation introducing the project’s goals, strategies, and results so far. Then, embark on a guided field tour of key restoration sites, including:

• Floodplain restoration at the former Redi-Mix Concrete Plant on Black Mountain Ranch
• Sediment control and road improvements on Zanardi and McIsaac Ranches (GGNRA land)

Explore how impaired dirt roads were decommissioned or upgraded and how stream crossings were redesigned to improve water quality and habitat. This innovative project targets priority areas where sediment threatens the survival of juvenile salmon—a critical concern for the Lagunitas Creek Watershed.

Watershed Conservation Manger, Ayano Hayes explains, “this project highlights how addressing erosion from upland roads can have a profound impact downstream. By reducing sediment delivery into Lagunitas Creek, we’re directly improving habitat conditions and water quality for endangered salmonids during their most sensitive life stages. This tour offers a unique opportunity to visit project sites on protected lands – and see the tangible results of this restoration work up close.”

See the transformation for yourself with dramatic before-and-after views, and gain insight into the design, implementation, and lessons learned from this impactful watershed restoration effort. This project was funded by the United States Environmental Protection Agency under the Federal Nonpoint Source Pollution Control Program (Clean Water Act Section 319) through an agreement with the State Water Resources Control Board.

Don’t miss this opportunity to witness real-world restoration work and connect with others working to protect California’s precious salmon habitat. 20 person attendance cap for the Field Showcase. Inquire and RSVP to Ayano Hayes, ahayes@tirn.net.

For more details on SPAWN’s habitat restoration work, the native plant nursery and how to get involved, please visit https://seaturtles.org/spawn/.

Turtle Island Restoration Network is a global ocean conservation nonprofit with offices in California and Texas, whose mission is to inspire and mobilize people around the world to protect marine biodiversity, the oceans and watersheds that sustain all life on Earth.

In a tentative ruling on September 16, 2022, CA Superior Court Judge Sweet ruled that the group that sued SPAWN and Marin County to prevent the restoration of San Geronimo Creek that runs through the former golf course owes SPAWN’s attorney $129,500 in attorney’s fees. 

This comes after the Judge ruled earlier this year against the San Geronimo Heritage Alliance (SGHA), “a group of 10 local residents who were unhappy about the sale of the former San Geronimo Golf Course, a private property sold by its previous owner in 2017,” after they sued to stop the restoration.

The ruling states,

“SPAWN’s Defense of the Case Vindicated an Import Public Interest

Working closely with local, state and federal agencies, SPAWN spent nearly a decade designing and permitting the restoration project…

SPAWN’s Litigation in this Case Was Necessary

SPAWN put forward evidence showing that the County expected it to defend and indemnify it against any challenges to the permits.  The defense was necessary to achieve the public benefit”

To read the tentative ruling, click here.

A final ruling is expected in the next few weeks. Stay tuned.

Meanwhile, SPAWN completed the final project while the lawsuit winded its way through Court.  To learn more about the restoration, click here.

Some of the recent work SPAWN has been involved with was highlighted in the American Society of Civil Engineers’ News and Information Hub. The work done at the former San Geronimo course was mentioned, where SPAWN helped create water-receiving floodplains and side channels benefitting wildlife.

The work was performed on land owned by the Trust for Public Land. It created five acres of floodplain habitat, restored riparian habitat, and installed a new 100-foot pedestrian bridge, allowing visitors to enjoy views of San Geronimo Creek and connect to trails around the 157-acre property.

The article discusses efforts to remove a failed sheet-pile-and-boulder structure and concrete fish ladder that had been installed decades earlier on a portion of the creek on the property. Now, a lot of work has been completed to help protect our beloved coho salmon.

There is still work to be done, and to stay up-to-date, be sure to regularly visit our website.

SPAWN is pursuing a sediment reduction project on GGNRA ranch lands to upgrade roads and improve road drainage networks. This will result in better watershed hydrology, reduction in sediment, removal of road stream crossings, and improved riparian habitat across one mile of existing road networks in lower Lagunitas Creek. The project will also restore one acre of floodplain habitat in the lower reach where a concrete and gravel lot will be restored to riparian floodplain habitat. The project is funded by the California State Water Resources Control Board through the Clean Water Act 319(h) grant program.  This project is in partnership with the National Park Service and the Marin Resource Conservation District.

SPAWN holds volunteer events throughout the year, and here are images from a recent outing!

Take a look at a quick gallery from our volunteer days! Thank you to all who have and continue to support our work; in the images, you can catch a glimpse of the great work our volunteers have done planting and more.

If you would like to participate and volunteer, find our available opportunities here.

Volunteers plant trees, shrubs, perennials, and grasses in downstream end of site.

Volunteers load mulch from pile to disperse around the site.

Volunteer Ken Wu removes invasive thistles from pathway.

Preston Brown, Director of Watershed Conservation, describes the restoration project.

Ayano Hayes, Watershed Biologist, gives planting demonstration.

Contacts: Preston Brown, Director of Watershed Conservation, 303-877-0880
Todd Steiner, Executive Director, 415-488-7652

SPAWN has completed removing Roy’s Dam and Roy’s Pools that were obstacles to salmon migration and replaced them with Roy’s Riffles! We completed this year’s work safely and on schedule.

The newly created creek-bed is functioning just as designed, with waters moving through at the very low “drought” condition flows (0.2 cubic-feet-per-second) we experienced just a couple of weeks ago. It has also been engineered to withstand flows up to 2,000 cubic-feet-per-second, anticipated during the largest 100-year storm event.

The contractors have now removed the screen on the fence and everyone can see what has been accomplished. The screen was placed on the fence because the heavy equipment operators were working right below the creek crossing at San Geronimo Valley Drive and were concerned for the safety of the folks who gathered there to watch. As boulders were being placed there was potential for stone chips to fly off and injure spectators. In addition the operators found the viewers a distraction to their work and personal safety. The curtain also was a partial barrier to dust created during demolition.

For now, all the heavy equipment work is complete. In early December, the new bridge will arrive and will be lowered on the new bridge footings by crane. This operation should take about a week.

We have begun re-planting the site with native species from our nursery and we are excited to see the willow cuttings already sprouting! Planting operations by hand will continue all winter.

If you are interested in helping, please join our mailing list to learn of upcoming dates. Unfortunately, the opportunity for volunteers to participate and public tours will continue to be limited by coronavirus and will be dictated by Marin County rules on gatherings, but we will do our best to accommodate everyone interested in being part of this historic restoration.