Photo courtesy of Leo Dale

This week in December marks the end of a multi-week Chinook salmon run throughout the Sonoma Creek Watershed which captivated the local community. Since late November, hundreds of Chinook have made their way up our watershed and have been spotted across the valley, including right in the heart of Sonoma. The last time the Sonoma Creek Watershed experienced a significant Chinook run was in 2021, which garnered similar excitement from community members and our team.

Multiple Chinook fighting upstream towards the base of Sugarloaf Ridge State Park’s waterfall. Here, they are nearing the end of their journey.

Chinook are one of three critical species that Sonoma Ecology Center focuses our watershed research and restoration on. As part of our mission at SEC, we aim to protect and restore local habitat for these threatened species, which also include the Central California Coast steelhead trout and California freshwater shrimp. Unlike steelhead trout and California freshwater shrimp which we see in our watershed every year, Chinook salmon require very specific conditions for their run—conditions which occur infrequently and years apart. Chinook are a fall-run species, meaning that in order to successfully migrate up Sonoma Creek, there must be adequate streamflow and water availability in the creek early enough in the rainy season. Because of the atmospheric river that hit the North Bay in late November and brought our waterways roaring to life, the right conditions were met for a Chinook run in Sonoma Creek this year.

Supporting salmonid populations and habitat is a larger part of our Upper Sonoma Creek Restoration Vision. Salmonid refers to the family of fish which includes the Chinook salmon and the Central California Coast steelhead trout. A goal of the Restoration Vision is to improve spawning conditions for adult salmonids, as well as winter and summer rearing habitat for juveniles. 

Chinook are the largest of the Pacific salmon, typically reaching around three feet in length and 30 pounds in weight. This Chinook was found off Warm Springs Road.

Historically, Sonoma Creek supported significant runs of steelhead trout, Chinook salmon, and Coho salmon. Today, we see smaller runs of steelhead and more infrequent runs of Chinook. Over the years, salmonid populations have declined significantly in our watershed. One reason for this is how extreme precipitation events in our region have impacted local salmonid habitat.

Over time, occurrences of extreme weather events like atmospheric rivers have increased in regions like Sonoma County. This causes “storm peaks” in our creeks. Rather than streamflow increasing slowly from a precipitation event and then tapering off afterward, storm peaks are strong torrential flows that immediately follow a big storm, and then drop back off quickly, leaving the creekbeds with diminished flow again just days after. When streamflow occurs in a concentrated fashion, it erodes the stream’s banks into steep channels and causes the bottom of the streambed to physically drop in place—a phenomenon known as downcutting or degradation. As climate warming continues, climate models project that the atmospheric rivers which drive these problems will only increase in frequency on the West Coast.

Streambank erosion resulting from storm peaks reduces floodplain habitat and streamflow in warmer, drier months, one factor which minimizes the success of rearing salmonid spawn. The Upper Sonoma Creek Restoration Vision is our plan to improve this degraded habitat and impacted streamflow in order to protect and restore spawning and rearing salmonids. 

This summer, SEC broke ground on the first major restoration project described in our Restoration Vision at Morton’s Warm Springs near Glen Ellen. Here, our planning team has been working to lower and widen the inset floodplain of the river corridor. Floodplain restoration allows the flood waters to both spread out and slow down, reducing erosion from the streambank.

A pool in the channel at Morton’s Warm Springs leading to floodplain habitat. Floodplains support a diversity of wildlife, from gravel-dwelling invertebrates on which salmonids and other aquatic animals feed, to the trees that shade them. 

The Restoration team has also planted over five hundred different native plants along the streambank at Morton’s, including integrated wildlife pathways down to the creek to ensure a healthy and vibrant ecosystem. Listen to Restoration Project Manager Lauren Claussen explain part of the habitat-building process at Morton’s in a video here.

Our work at Morton’s is funded by the Environmental Protection Agency’s San Francisco Bay Area Water Quality Improvement Fund, as well as California Fish & Wildlife’s Watershed Restoration Grant Program (which is funded by the Water Quality, Supply, and Infrastructure Improvement Act of 2014). 

Sonoma Ecology Center’s Restoration team planting natives along the streambank at Morton’s. The project included over forty different native species.

This year, Chinook salmon have been spotted everywhere our Restoration team has current, ongoing habitat restoration projects—including areas like Nathanson Creek, Rodgers Creek, and soon in Calabazas Creek. These restoration projects are funded by Sonoma Water Agency as part of their Watershed Partnership Program.

We suspect that many of the Chinook that returned to our watershed this year may be the very same that hatched in Sonoma Creek during the last Chinook run three years ago. Chinook salmon are typically 3-4 years old when they attempt to return to their original spawning grounds. Others may be from hatcheries, as indicated from their missing adipose fins. Depending on their starting point from the Pacific Ocean through San Pablo Bay, some of these fish may have traveled over 100 miles. 

These videos are just a couple of the many shared by community and staff members during the Chinook run this year. On the left, Chinook are spotted near Temelec. On the right, multiple Chinook swim upstream in Fryer Creek.

Chinook in Calabazas Creek along Nuns Canyon Road, captured by Research Project Manager Steven Lee.

If we continue to see these occasional returns of Chinook salmon to Sonoma Creek, “eventually they’ll be able to start calling our watershed home,” says Research Program Manager Steven Lee. 

At Sonoma Ecology Center, we are grateful to be a part of protecting, building, and preserving salmonid habitat throughout the Sonoma Creek Watershed. And when we’re lucky enough to watch our creeks come alive with Chinook runs like this year, our work becomes all the more rewarding. In the future, with more resources, we hope to be able to conduct further population surveying and monitoring so that we can track the success of these incredible fish. 

While we are thankful to take part in stewarding the Sonoma Creek Watershed, we would like to acknowledge that the land we know as the Sonoma Creek Watershed is the ancestral territory of the Pomo, Coast Miwok, and Wappo peoples, who have occupied and stewarded this land for the last 12,000 years.