Work resumed on the lower Yuba River earlier this month on a $12 million project designed to enhance the river’s ecosystem by increasing available juvenile salmon habitat to improve the natural production of Chinook salmon and Central Valley steelhead — both of which are listed as threatened under the Endangered Species Act.
The Hallwood Side Channel and Floodplain Restoration Project is intended to give young salmon and steelhead areas to hide from predators, allowing them to eat and grow in preparation for their eventual journey out to the ocean. Enhancement work includes land surface changes, riparian planting and placement of large woody material embedded to simulate a more natural river at key locations.
Another added benefit of the project is that it will reduce flood risk through lower water surface elevations and velocities during flood events.
“(Once) the four-phase project is complete, which is expected in late 2024, the project will restore 157 acres of floodplain habitat including 7 miles of seasonal side channels, alcoves and swales,” said Jeff Mathews, senior project manager for the Yuba Water Agency. “In addition, more than 3.2 million cubic yards of material will be removed from the floodway, resulting in about a 3-foot reduction in water surface elevation during peak flows. This is a true multi-benefit project, which benefits both fish and flood risk reduction goals.”
Phase one was completed in November 2020 and saw approximately 1.5 million cubic yards of course surface material removed and restoration work to 89 acres of juvenile floodplain rearing habitat, which provides 1.7 miles of perennial side channels and 3.7 miles of seasonal side channels, alcoves and swales.
The second phase of the project began on April 1 and will see crews remove approximately 800,000 cubic yards of sediment from the river’s Middle Training Wall and surrounding floodplains, as well as enhancement work to 34 acres of floodplain and seasonally inundated side channel habitat.
The Yuba River is constrained by tall linear cobble embankments called training walls, which were constructed in the early 1900s by hydraulic dredges following the Gold Rush. The Middle Training Wall is located in the middle of the river that runs more than 2 miles along the length of the project area.
To allow crews to work along the river, the lower Yuba River is closed to all watercraft until Dec. 1, from Daguerre Point Dam to 6,000 feet downstream.
Phase three and four will remove large portions of the Middle Training Wall, yielding approximately 815,000 and 400,000 cubic yards of sediment, respectively, and enhancing an additional 13 and 21 acres of floodplain and seasonally inundated side channel habitat.
“This is really an incredible public-private partnership that shows how much more good we can do when we all work together for a common goal,” Mathews said. “This project includes the U.S. Fish and Wildlife Service, Wildlife Conservation Board, California Department of Fish and Wildlife, Teichert, Western Aggregates, cbec Eco Engineers, South Yuba River Citizens League, Cramer Fish Sciences and Yuba Water Agency.”
Funding for the $12 million project has been provided by the U.S. Fish and Wildlife Service, California Department of Fish and Wildlife’s Proposition 68 grant program, and Yuba Water. Helping to make the project feasible, Teichert is providing an in-kind contribution to remove the aggregate from the project area, which will then be processed at their Hallwood plant — mined aggregate is processed and used in numerous public works projects throughout the region.
“This project would not be possible without the cooperation of the Teichert Companies and Western Aggregates,” Mathews said. “Without their cooperation and support, the project would not likely be cost effective.”
Mathews said all four phases are expected to be completed by fall 2024.