Corps pilot project seeks to learn from nature, building fish “clubhouses” on lower Yuba River
Credit: US Corps of Engineers
CRAMENTO, Calif. – Creating an underwater environment that protects young salmon along the lower Yuba River in northern California – that’s the goal of a pilot study by the U.S. Army Corps of Engineers Sacramento District.
Juvenile salmon, like teenagers, enjoy finding a place to hang out and eat with friends, so Corps biologists have placed experimental fish hideouts along the lower Yuba, imitating natural drift wood deposits. The Large Woody Material Management Program is designed to enhance rearing conditions in the lower Yuba River for spring-run Chinook salmon and Central Valley steelhead and includes placing collections of specifically-sized logs and tree roots at varying locations along the lower Yuba.
The wood used in the study was collected from New Bullards Dam and placed at Lost Island Bar on the lower Yuba. Key large wood pieces, either root wads or branches longer than 24 feet, were used to anchor each fish hideout complex. Placement of wood for the pilot study was completed Dec. 11. “There are two primary objectives for the pilot study – to evaluate the stability of the manmade complexes during flood flows and to document how varying flows in the river transport pieces of the structures downstream,” said Brian Mulvey, a Sacramento District fisheries biologist. Specific pieces of the wood have been tagged for later identification, which will be used to assess the effectiveness of wood placement in the lower Yuba River and help develop a long-term program.
“We are working to replenish the supply of large woody material back in the lower Yuba, providing in-stream cover for juvenile fish, while still respecting the safety needs for boating and rafting,” said Mulvey.
This pilot study, along with previous work to add suitably-sized gravel to enhance salmonid spawning along the lower Yuba, are part of the Corps’ voluntary conservation measures associated with Daguerre Point Dam, which was constructed to prevent hydraulic mining debris from washing downstream and blocking the navigation channel of the Sacramento River.