This Winter's Lagunitas Coho Trace Back to a Banner Run
October 22, 2026
October 22, 2026
The coho salmon expected in Lagunitas Creek this December come from a strong run, and the last two winters don't show that. Most coho return to spawn in their third year. That makes this season's adults the offspring of the 2023-24 run, when Marin Water's fisheries crew counted 343 coho redds, the gravel nests females dig, across the Lagunitas watershed. That total was 48% above average and nearly double the count from three years earlier.
Those fish will reach a stretch of creek next to the Leo T. Cronin Fish Viewing Area where Marin Water has been adding logs and gravel this fall, with the work scheduled to finish by late November. Marin Water's fisheries program manager calls that reach one of the creek's historically busiest for coho spawning.
Put those two facts together and this December is a good one to put the Shafter Bridge trip on the calendar.
Lagunitas coho run in three overlapping year-classes, and each one tends to rise or fall with its own history. Marin Water's survey crews walk the creek every week from November through March looking for new redds. The coho redd count is the district's most reliable way to estimate how many adults came back. The two seasons that matter most this winter look very different on paper:
| 2023-24 run, the parents of this winter's fish | 2025-26 run, last winter, preliminary | |
|---|---|---|
| Coho redds | 343, final | 77 through January |
| Live coho observed | 693 | More adults than three years earlier, per Marin Water |
| Chinook | 11 redds, below average | Record numbers |
| Chum and pink salmon | None observed | A few of each, both rare here |
| Redds of all species | Not the headline figure | 347 counted, 91 still unclassified as of February |
Last winter's 77 coho redds would rank among the smallest runs in 30 years if that number held. In its February 2026 update, Marin Water said not to take it at face value. Record Chinook, a few chum and pink salmon, and unusually early steelhead were all spawning in the same weeks as the coho, and many empty redds couldn't be tied to a species right away. The district expected the final coho estimate to come in higher once those unclassified redds were sorted out.
The weather added to the confusion. Rain came unusually early in fall 2025, and flows topped 100 cubic feet per second three times. Crews saw more than 100 coho in the creek early on, but few were spawning. Most were holding in pools and waiting for more rain.
The San Geronimo tributaries gave a clearer partial picture. In September 2026, SPAWN, a program of Turtle Island Restoration Network, released its final tributary survey: 28 coho redds across six San Geronimo Creek tributaries. Arroyo Creek had 12, Montezuma seven, North Fork San Geronimo two and Larsen one. Willis Evans Creek had none. SPAWN called that a modest improvement for the tributaries. It also said spawning across the whole watershed had not risen above the low point of three years earlier.
So last winter belonged to a weaker year-class that was hard to count. This winter belongs to a stronger one.
A strong parent run is a starting point, not a forecast. Neither Marin Water nor SPAWN has published a number for the 2026-27 return. The steps in between can be followed, though. Marin Water estimated about 47,000 juvenile coho in the watershed in 2024 and 28% overwinter survival. In 2025, an estimated 13,086 young coho headed out to sea as smolts. The district called that above average, though somewhat smaller than the group that left three years earlier.
Those smolts have spent about a year and a half in the ocean. Ocean conditions, early-winter rain and how long the creek stays muddy will decide how many come back and when they're visible. The family line is sound. How the numbers turn out depends on the Pacific and the weather.
The main stem got work too while these fish were at sea. Marin Water's Lagunitas Creek Watershed Enhancement project has been adding logs and gravel to selected sites between Peters Dam and Samuel P. Taylor State Park. The goal is cover for adult fish and deeper, slower pools where young coho can grow. The Marin Independent Journal reports the full project covers 13 sites along 4,450 linear feet of channel, with more than 270 logs and thousands of tons of gravel.
This fall's piece of the project is Phase 1C, a single site near the Leo T. Cronin Fish Viewing Area. In May 2026 the district hired Hanford Applied Restoration and Conservation under a $1.13 million contract, with work scheduled from August into the fall. In the same Marin IJ story, Jonathan Koehler, the district's fisheries program manager, explained why this site matters:
"This is the final site of phase one, which will bring our total number of sites to eight. This reach has historically been one of the highest spawning density reaches for coho, and so it's exciting that we've hopefully really improved conditions in that section of the creek that the fish want to use the most."
The district's board staff report lists November 20, 2026, as the estimated completion date, so crews could still be wrapping up as the first rains arrive. Last fall's construction season showed how this tends to go. Marin Water limited access at the Leo T. Cronin lot during the work, then lifted the restrictions once that season ended. Last year's work also used what the district calls a "stone slinger," a high-speed conveyor that throws gravel from the top of the bank into the creek bed with little disturbance to the banks.
If you've watched from Shafter Bridge in past Decembers, the logs and pools below may look different this year.
Marin Water says December is usually the best month to see coho. The best viewing comes a day or two after a significant rain, once the water starts to clear. The basics for this season:
Marin Water's crews will start their weekly redd surveys in November, as they do every season. The first counts from this year-class should show up in the district's updates over the winter, along with the delayed final numbers for last season. Those updates will be the first real evidence of how the 2023-24 run's offspring did at sea.
A December morning at Shafter Bridge is one of the West Marin routines that helps people get to know a place, and we love talking about the parts of the North Bay that don't show up in a listing. If you're thinking about a move nearby or just want to compare notes on this season's run, Rob Sullivan is glad to talk. Let's Connect.
If you are seeking a real estate professional whom you can trust and count on for the long haul, then look no further. Rob will earn your loyalty and turn your dreams into reality.
