Nimbus Fish Hatchery to Increase Chinook Salmon Production by 500,000 Fish on the American River

The California Department of Fish and Wildlife (CDFW) and the U.S. Bureau of Reclamation have announced a joint effort at the Nimbus Fish Hatchery in Sacramento County to increase production of fall-run Chinook salmon by 500,000 smolts to help combat effects of the drought.

Spawning of returning fall-run Chinook salmon begins this week at the Nimbus Fish Hatchery on the American River. The hatchery typically produces 4 million Chinook salmon smolts for release into the American River and locations in San Francisco and San Pablo bays. This year, production goals have been increased to 4.5 million salmon smolts.

“Chinook salmon returns to the American River declined significantly during California’s last drought,” said Jason Julienne, supervisor for CDFW’s North Central Region fish hatcheries. “We’re using those observations and that experience to get ahead of any population declines this time around by increasing production to help sustain this important salmon run.”

The lower American River supports both wild and hatchery produced fall-run Chinook salmon and has undergone several habitat restoration projects in recent years to improve natural production.

The American River once provided approximately 100 miles of spawning habitat for native Chinook salmon and steelhead trout. With the construction of the Nimbus Dam and the creation of Folsom Lake, these fish lost access to most of their historical spawning and rearing habitat. The U.S. Bureau of Reclamation designed and built the Nimbus Fish Hatchery in 1958 to mitigate for lost habitat and currently pays CDFW to operate and maintain the hatchery.

Most, if not all, of the additional salmon smolts produced at the Nimbus Fish Hatchery will be trucked and released at sites in the San Pablo and San Francisco bays to improve survival and further evaluate several new release points used last spring when American River conditions were too poor to release the juvenile fish. Consistent with current strategies, 25 percent of the additional fish will have their adipose fins clipped and coded-wire tags installed to identify them as being of hatchery origin and provide scientists with data about their ultimate fate and life journey.

“This project exemplifies our ongoing partnership with the California Department of Fish and Wildlife on the American River and our common goal to safely collect Chinook salmon and steelhead for spawning to meet Reclamation’s mitigation requirements for the construction of Nimbus Dam,” said Drew Lessard, Reclamation’s Central California Area office manager.

Similar proactive measures are being taken at CDFW’s Feather River Hatchery in Butte County where fall-run Chinook salmon production will be increased by 1,750,000 smolts this fall.

Ocean commercially and recreationally caught salmon generate more than $900 million annually for California. Economic benefits from ocean caught salmon sold in markets to the purchase of fishing boats, fishing equipment, related travel and transportation by recreational anglers in pursuit of these salmon make a significant contribution to California’s economy.

CDFW and the Bureau of Reclamation today also announced the completion and opening of a new fish ladder(opens in new tab) into the Nimbus Fish Hatchery. The new fish ladder has been designed to improve hatchery operations and the entrance relocated upstream to open up additional in-river spawning and rearing habitat for salmon and steelhead. The new fish ladder also improves the visitor experience with underwater viewing windows and outdoor gathering space.

The Nimbus Fish Hatchery remains closed to the public due to COVID-19 precautions but the lower portion of the fish ladder and related outdoor viewing areas are open to public access.