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Monday, April 15, 2024

Chinook salmon run renewed in Putah Creek

A new bird-watching club at UC Davis organizes walks in the Putah Creek area

By RACHEL SHEY city@theaggie.org

One of the main waterways near Davis is Putah Creek, which has a history intertwined with human activity in the Central Valley and California. It is currently experiencing a wildlife revival, according to UC Davis Wildlife, Fish, and Conservation Biology faculty Andrew Rypel.  

Putah Creek proper is a natural creek,” Rypel said. “It originates in the Mayacamas Mountains, and is impounded at Lake Berryessa, and it flows down past Davis and the Yolo Bypass and then ultimately into the Sacramento River.”  

Rypel said that the portion of Putah Creek which “flows” through the Arboretum is no longer actually connected to the creek. This portion of the creek is largely stagnant, due to being a drainage water body supported largely by rainfall and runoff.

“But then there’s the Arboretum waterway, which is the duck pond and flows right through the middle of campus,” Rypel said. “That used to be part of Putah Creek, but that’s excised from the creek now.”

Arboretum Assistant Director Andrew Fulks stated that there is currently a project to reduce the stagnancy of the waterway. Observers of the creek can see that it is often full of algae in certain areas and the water moves extremely slowly, if at all.  

Given that the waterway was disconnected from the main channel of Putah Creek, it has largely been stagnant since it was disconnected,” Fulks said. “We are working on a project to recirculate flow within the creek to prevent stagnation.”  

Putah Creek used to be much drier, Rypel said, with essentially all of the water removed for various uses. A lawsuit filed by concerned UC Davis faculty and others saved the creek. Since 2000, it’s been replenished, allowing native fish populations to recover. The creek is still not at full capacity as 95% of the water in the creek is impounded for human use. 

“In Davis in the 1990s, Putah Creek was a horrible place to be a fish,” Rypel said. “The creek would dry up during the summer, there was a gravel mining operation, and what happened was that… the Putah Creek Council and the University of California sued Solano County Water Agency using a state fish and game code that stipulates that dam operators have to provide conditions below dams to keep native fish populations in healthy conditions.”  

It is unlikely that Putah Creek will ever dry up again, according to Fulks. Because Lake Berryessa is generally supplied by “atmospheric rivers,” or rainwater, it is not in danger of going dry like a reservoir that’s supplied by snowmelt.  

“Now that we have secured flows from Monticello dam, the creek isn’t in danger of drying up,” Fulks said. “You’d have to have a drought of epic proportions to get to the point where the creek dried up, and at that point, all the water behind the dam would be gone. There would be larger societal issues to be worried about if that happened.”

In a few weeks, Chinook salmon will be present in Putah Creek, Rypel said. This represents a major success in the rehabilitation of the creek. Interested observers can now see salmon eggs, salmon underwater, and dead salmon on the banks.  

“Around the year 2013, out of the blue, Chinook salmon started showing up,” Rypel said. “At first it was just a few fish, but the number of salmon coming to Putah Creek has increased every year after that. We think that now we have a self-reproducing run of Chinook salmon in Putah Creek.”  

These salmon likely originated from confused hatchery salmon. Since they never imprinted on a native stream, they can end up in streams all over California to spawn.  

“In the last route, to increase the survivorship of salmon out to the ocean, the agencies trucked the fish down to the delta, so that they could have really good survivorship out to the ocean gates, but what happens when you do that is when the fish come back as adults, they stray,” Rypel said. “They don’t imprint on their native stream, so the fish go all over the place and a lot of them ended up in Putah Creek. Those fish formed the basis of a salmon run in Putah Creek.” 

Not only is Putah Creek home to salmon, it’s also a great wildlife area to see birds, according to UC Davis Bird Watching Club President Cameron Tescher. The club took a trip to the creek recently and saw numerous species of birds, some of which were quite uncommon. 

“Near Putah Creek, we saw some really interesting birds, we saw white-throated sparrows, Lewis’s woodpeckers, black-throated grey warbler and red-breasted sapsucker,” Tescher said.  

Tescher is planning a trip to the Putah Creek Canyon area with the club. They hope to see some unusual birds and enjoy the diverse and species-rich habitat.

“In the Putah Creek Canyon area, some good birds that we could see there include Stower’s Jay, Eurasian Wigeon and Rufous-crowned Sparrow,” Tescher said. “And there’s a great diversity of oaks, riparian areas and the creek, and it will lead to a lot of birds in general, lots of waterfowl, lots of songbirds.”  

Tescher said that the club will be involved in the Christmas Bird Count, which occurs in the Putah Creek area in December.

“Oh, yes! We’re actually having a presentation in late November done by two of the people who run the Putah Creek Christmas Bird Count,” Tescher said.

Written by: Rachel Shey — city@theaggie.org

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