The 2026 water year, which began on October 1, started off great for Marin County. In fact, rain started falling in September, and by mid-November, over nine inches had fallen. Stream flows in Lagunitas Creek rose above 100 cubic feet per second on three occasions, which provided unusually early and favorable conditions for salmon to migrate upstream and spawn. Chinook (aka “king”) salmon are typically the first species to arrive in Lagunitas Creek, and this year, many of them took advantage of those early flows.

Marin Water surveyors counted 149 Chinook salmon on November 12, shattering a single-day record for this species. The following week, an astonishing 70 Chinook were observed in the short section of creek between the Leo T. Cronin Fish Viewing Area and Peters Dam. Over 50 Chinook were also observed in San Geronimo Creek all the way to Woodacre. By early December, our team documented 119 Chinook salmon redds (nests), which is just shy of last year’s record. We will almost certainly establish a new record by the time Chinook salmon spawning wraps up in early January.

Over 100 coho salmon have also been observed taking advantage of the early rains to migrate upstream but unlike Chinook, very few of them have spawned. Most of the coho in Lagunitas and San Geronimo Creeks are holding in deep pools, apparently waiting for more rain before choosing good places to lay their eggs.

Will December bring more coho spawning?

Salmon need fast-flowing water to help them dig a pit and bury their eggs. Some coho in Lagunitas Creek may use the water being released from Kent Lake to move all that gravel, but most will wait for rain and higher stream flows. Rain is currently forecast to return next week, which could set off the busiest spawning period of the 2025-26 season. Hopefully the rain will be followed by a few days of clear weather so we can all see the spawning activity unfold.

Dive into the Data

Keep up to date with the latest salmon data on Marin Water’s Lagunitas Creek Spawner Dashboard.