If you stood on the trail at the Leo T. Cronin Fish Viewing Area in the winter of 2024–25 and found more red-backed coho than you had ever seen there, should you expect the same this December?
Marin Water's fisheries reports suggest you shouldn't. In 2024–25, surveyors counted a record 697 coho redds and 1,702 live coho across the Lagunitas Creek watershed, for an escapement estimate of 1,394 adults. The district's 2024–25 adult monitoring report calls it the largest run in 30 years of annual spawner surveys. It also says the run reached the federal recovery plan's halfway mark at least 35 years earlier than that plan had predicted. The record run's offspring won't be back until the winter of 2027–28. This winter belongs to a different set of fish.
Coho Come Back on a Three-Year Clock
Coho salmon in Lagunitas Creek spend roughly 18 months in freshwater, counting incubation. They then spend about 18 months in the ocean and return to spawn in their home stream in their third year. Marin Water uses that cycle to sort the population into year classes three years apart. Each winter's run is its own family line, and the three lines rise and fall independently.
Here is how the last three winters line up, along with the one about to start:
| Spawning winter | What was counted | Year class it belongs to |
|---|---|---|
| 2023–24 | At least 283 coho redds watershed-wide, provisional | Parents of this winter's fish |
| 2024–25 | 697 redds, 1,702 live coho, record | Returns again in 2027–28 |
| 2025–26 | 28 redds in six San Geronimo tributaries; no watershed-wide total published | Returns again in 2028–29 |
| 2026–27 | Season begins this fall | Offspring of the 2023–24 spawners |
The 2023–24 figure comes from a March 2024 Creek Notes update by Marin Water's Eric Ettlinger. Marin Water crews counted 170 redds on the streams they survey, the National Park Service counted more than 70 on Olema Creek, and the Salmon Protection and Watershed Network, known as SPAWN, counted 43 in the San Geronimo tributaries. The total of at least 283 was more than 60% above that year class's previous generation. That season is the best guide to this one, because the fish arriving this winter are the offspring of those 283-plus nests.
What the Smolt Trap Saw When This Winter's Fish Left
Marin Water tracks every year class twice before it returns: once as juveniles in summer, and again as smolts heading to sea in spring. This winter's fish came through both counts.
According to the district's 2024–25 juvenile and smolt report, published in August 2026, juvenile coho in the watershed numbered about 47,000 in 2024. That was the second-highest juvenile count in 30 years. In spring 2025, the rotary screw trap on Lagunitas Creek caught 5,357 coho smolts, which produced an outmigration estimate of 13,086. Marin Water called that outmigration above average and similar in size to the parent generation three years earlier.
Between those two counts, many fish were lost. Of the juveniles tagged in 2024, only about 28% appear to have survived the winter and reached the smolt trap. Coho tagged in San Geronimo Creek did worse, at 21%. The report calls both figures surprising, because high flows from late November through mid-February 2025 should have protected the fish from predators. The effect of the large February 2025 flood, the seventh-largest in more than 50 years, is unknown. Smolts from the Lagunitas mainstem fell 21% compared with 2022. Higher smolt numbers from Olema Creek, which the National Park Service monitors, partly made up the difference.
The record cohort had a different start. Marin Water traces the 2024–25 run to low stream flows in the winter of 2021–22, which led to high incubation survival and record numbers of juveniles and smolts. Ocean survival for those fish was a typical 2.8%, and that was enough for a historic return. This winter's fish left the creek in good numbers. They did not leave in record numbers. How many come back depends on 18 months at sea that no one has measured yet, and no agency has published a forecast for 2026–27.
The most likely picture is a solid, above-average season, closer to the 2023–24 count than to the record.
Last Winter's Signal From the Tributaries
Last winter's returns, from the 2025–26 year class, add some context. SPAWN, a program of Turtle Island Restoration Network, surveyed about 3.4 miles across six San Geronimo Creek tributaries and counted 28 coho redds and 30 live coho. Arroyo Creek led with 12 redds, followed by Montezuma Creek with seven, the North Fork of San Geronimo with two and Larsen Creek with one. Willis Evans Creek had no salmon at all. SPAWN's September 2026 write-up also notes that watershed-wide coho numbers for that season did not rise from the low count three years earlier.
"This year's survey provides a reason for hope, but not complacency," said Todd Steiner, SPAWN's founder. He tied the strong results on Arroyo and Woodacre creeks to old culverts that have been replaced or modified so fish can pass. Ken Bouley, executive director of Turtle Island Restoration Network, is urging Marin County to restart its San Geronimo culvert replacement program, which SPAWN says went dormant about a decade ago. Each year class has a different starting size and a different set of barriers to get past. The tributary results are one more reason not to expect this winter to match two winters ago.
The Creek at Cronin Has Been Reworked
The viewing area has changed too. Marin Water's Lagunitas Creek Watershed Enhancement Project, under way since 2019, targets 13 sites along roughly 4,450 feet of channel. By fall 2025, crews had placed more than 270 logs and 11,000 tons of gravel. The district said the completed improvements appeared to be functioning as intended.
The final Phase 1 site, called Phase 1c, sits next to the Leo T. Cronin Fish Viewing Area. The Marin Independent Journal reported in May 2026 on a $1.13 million contract for that work, planned from August through fall. Jonathan Koehler, Marin Water's fisheries manager, described the reach as historically one of the highest-density coho spawning areas in the watershed. The paper also reported that Phase 2 is slated to begin construction in 2027 to finish the five remaining sites. A $1.1 million state grant secured in 2026 covers two of them, and about $4 million is still needed for the full project. Marin Water's July 2026 project update put Phase 1c in an August–October 2026 window, with about half of all sites complete.
Spawners arriving this winter will be among the first to use the new gravel and log structures in that reach. Marin Water's site describes the shallow water just upstream of the Cronin parking lot as consistently one of the busiest spawning areas on Lagunitas Creek.
The district had not posted a completion notice for Phase 1c as of early October 2026. Its visitor pages also did not mention any closure for this phase. Last year was different. Phase 1B work closed the Cronin viewing area at Shafter Bridge from August through November 2025.
Planning a Visit This Winter
- Timing. Marin Water lists the Cronin spawning window as December through January. The National Park Service's coho viewing page lists the Shafter Bridge parking as open seasonally from December through February. Marin Water names December as the most reliable month and suggests going after significant rain, once the water has cleared.
- Getting there. Take Sir Francis Drake Boulevard west through the San Geronimo Valley and cross Shafter Bridge, about half a mile west of the Lagunitas store. Turn left right away into the lot. If you reach the Samuel P. Taylor State Park sign, you have gone too far. The site is open from sunrise to sunset. The lot is small and fills quickly, especially on weekends.
- Across the road. Salmon can sometimes be seen jumping a small waterfall on the opposite side of the road from the viewing area.
- Other spots. The National Park Service also lists Camp Taylor and Devil's Gulch in Samuel P. Taylor State Park as places to watch the run.
- Guided walks. Last season, SPAWN ran guided creekwalks for $15 per nonmember, with groups capped at 15 people. As of October 8, 2026, SPAWN's events calendar had no 2026–27 dates posted.
- Updates. Marin Water's fisheries team posts survey results through its Creek Notes series, which also has an email subscription. Check it or the district's visitor page before driving out, in case the Phase 1c work runs past its October window.
If 2024–25 is your only reference point for this creek, a December visit this year will probably look different. It will be a steady run from a year class that left the creek above average, spawning in a reach that Marin Water scheduled for rebuilding this fall.
Aviva Kamler follows West Marin closely, from the creek restoration work along Sir Francis Drake to the projects scheduled for 2027. If you own a home in the San Geronimo Valley or nearby and want to know what it is worth right now, request a personalized home valuation. We'll walk you through it clearly and at your own pace.
