Photo by Ken Davis

New Insights into Putah Creek Salmon

Oct 18, 2020 at 8:00am

Malte Willmes, Anna Steel, Levi Lewis, Peter Moyle, and Andrew Rypel

It’s November 2016, and we’re out in canoes on Putah Creek as part of the annual salmon survey. Just as we navigate our watercraft through a narrow river section using push poles, thorny blackberry bushes and trees begin to close in from both sides of the channel. Finally, we reach a series of shallow riffles and spot our first salmon of the day. As we look it over, it’s easy to consider this fish, the ordeal it went through to get here, and how its journey symbolizes in some way the restoration of Putah Creek.

Putah Creek is a small stream originating on the East side of the Vaca Mountains. Flowing down-slope, water enters Lake Berryessa, a large impoundment created by Monticello dam. Below the dam, the creek flows to Putah Creek Diversion Dam, past the town of Winters, UC Davis, and dozens of farms and into the Yolo Bypass. From here it eventually flows into the San Francisco Estuary and the Pacific Ocean.

Chinook Salmon (Oncorhynchus tshawytscha) have become a welcome and familiar sight in recent years in Putah Creek. Considered a keystone species across the Pacific Northwest, Chinook Salmon hold a special place in our past and present as a cultural and food resource. This includes for indigenous peoples of California, such as the Patwin people, on whose land UC Davis is located. In California at the southern end of Chinook distribution, populations are in decline, due to combined effects of habitat degradation, water diversions, and climate change (Moyle et al. 2017). Putah Creek historically supported a population of fall-run Chinook Salmon (Yoshiyama et al. 1998). And while the creek had long been known to possess an intermittent hydrologic dynamic (Shapovalov 1940), reduced downstream flows after Monticello Dam was installed proved problematic. For example, areas of the creek dried more frequently during summer months, resulting in declines and extirpation of many anadromous and native fishes, including Chinook Salmon (Oncorhynchus tshawytscha). Their reappearance now is a direct result of ongoing restoration and water management efforts, particularly since ~2000.

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