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Elk Grove Citizen

Ready for Fall Run

Sep 29, 2021 12:00AM ● By Story and photos by Susan Maxwell Skinner

Fish and Wildlife Department staffer Stephanie Ambrosia surveys fish ladder extensions built to conduct spawning salmon to hatchery processing beneath Nimbus Dam. Recently completed, the $9.7 million flume begins operation in November.

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SACRAMENTO REGION, CA (MPG) - A $9.7 million project extending Nimbus Hatchery’s famous fish ladder into Nimbus Basin is complete. The hatchery’s outdated weir and ladder system last year served a final season. When the new passage is activated this November, salmon will take an elongated route to fishery processing. Their 1,900 ft climb will offer visitor viewing windows and a “Sam-Cam” to observe heroic Chinooks ending their lifecycles hundreds of miles from the Pacific Ocean.

Three years in construction, the ladder and its water-level flume are designed to lead those fish that have not spawned naturally to hatchery fertilization. Egg and milt harvesting began here in the 1950s, after dam construction blocked migratory paths for American River salmon and steelhead. To divert returning fish, a picket weir previously spanned the American River below Hazel Bridge. The device was laboriously dismantled every January and though the weir operated adequately for 65 seasons, a better system has long been on Fish and Wildlife Department wish lists. “The new construction,” predicts Bureau of Reclamation project engineer Mark Curney, “will increase the hatchery’s operational flexibility and improve public and employee safety.”

Many migrating fish breed and die before reaching the facility.  Currently under construction, a gravel bed restoration project near Ancil Hoffman Park will increase mating chances by adding 16,000 yards of gravel to existing beds. The altered American River nevertheless still offers insufficient nesting locations and to mitigate, the Nimbus facility must hatch and dispatch thousands of fry every spring.  These reach maturity after several years in the ocean then instinctively head upstream to spawn new generations.

Though recent heatwaves have warmed the American River, it is hoped that water temperatures cool to preferred breeding frigidity by November. Fish that reach Nimbus unfulfilled will be lured by churning water. Piped from Lake Natoma, this torrent will fill a 150-yard flume that precedes the final climb. The channel is entirely caged to protect salmonids from poaching and debris; nearby riverbanks are permanently closed to anglers. The new ladder parallels a realigned bike trail that runs between Nimbus and Lake Natoma.

Hell-bent on reproduction, fish will encounter submerged barriers, a 10-foot deep pond and concrete steps. Visitor lookouts are positioned to enhance viewing. “We’ve wanted submerged windows for ages,” says Nimbus interpretive specialist Stephanie Ambrosia. “It’s a great way to show how fish group; how they rest between steps and the physiological changes that occur during their long journey from the ocean. Some have bones exposed and fins hanging off. These changes are more visible from underwater.”

Some nature lovers might miss the autumn spectacle of massive Chinooks challenging the old hatchery weir. The barrier will nevertheless not be scrapped; its metal sections will remain in storage for emergency service. Heralding a new age of California State Hatchery efficiency, a 60-foot mural was last week completed on the facility grounds. San Francisco-based artist Max Erhman’s canvas spans the walls of silos that store fish food near the visitor center. The work was funded by Wide Open Walls, a  street art nonprofit supported Sacramento Metropolitan Arts Commission. Central to Erhman’s design, a steelhead bursts from the river to symbolize nature’s leap of faith to the future.

Nimbus Hatchery is located at 2001 Nimbus Rd, Gold River. Facility parking is open and the completed fish ladder may be viewed from walking trails. The Salmon and steelhead spawning season runs from November to March. For more information, visit: