Lower Yuba River Hallwood Channel and Floodplain Restoration Project

The Project (also referred to previously as “Daguerre Alley”) is designed to restore and enhance ecosystem processes within an important reach of the Yuba River.

The primary project focus is on enhancing productive juvenile salmonid rearing habitat to increase the natural production of fall‐run and spring-run Chinook salmon (Oncorhynchus tshawytscha) and Central Valley steelhead (O. mykiss). cbec leads the project team that is working to directly address the U.S. Fish & Wildlife Service’s Anadromous Fish Restoration Program’s doubling goal for anadromous salmonids.

The Project will enhance and create up to 157 acres of seasonally inundated riparian floodplain habitats, more than 1.7 miles of perennial side channels and alcoves, and more than 6.1 miles of seasonal side channels, alcoves, and swales. The design approach focuses on removing unnatural constraints (such as a mid-river training wall and coarse surface materials) in order to allow natural river and floodplain processes to function. cbec leads the consultant team with primary support from Cramer Fish Sciences, and the South Yuba River Citizens League (i.e. Rachel Hutchinson and others). Phase 1A construction began in summer 2019, and was completed in summer 2020. Phase 1B, construction of habitat channels, graded floodplains, and riparian planting began in July 2020 and will extend through November 2020. This is a large multi-year project and implementation is forecast to take between 4 and 6 years to complete.

As part of this project, cbec has performed a number of topographic and bathymetric surveying efforts in support of the hydrodynamic modeling and design process. Survey work has included foot-based RTK GPS surveys of the floodplain areas, drone-based structure-from-motion topographic surveys, and bathymetric surveys with both a remote-controlled boat and a jon boat outfitted with a single-beam echosounder. In addition to characterizing rived bed and floodplain topography, surveys have determined crest elevations of the middle and northern training walls along this corridor of the lower Yuba River. Survey data have been incorporated into a surface that has allowed differencing analysis with prior LiDAR data to determine geomorphic change of the site. Field campaigns also verified extents of vegetative cover to inform roughness values used in the hydrodynamic model.

Throughout the life of this project, cbec has prepared multiple grant applications to pursue funding. Furthermore, cbec developed initial project concepts in 2012, and has led project design to 100% level, implementation planning, and led Central Valley Flood Protection Board (CVFPB) Encroachment, Corps Section 408, and State Mining and Geology Board permitting efforts. As part of leading the design development, cbec developed and calibrated two-dimensional (2D) hydraulic models (SRH-2D by USBR) for both high flows and low ecologically functional flows. The high flow models were used to support the CVFPB Encroachment Permit process. Low flow models were used to inform design and to quantify project benefits as suitable habitat areas using habitat suitability indices for target species. Geographic information systems (GIS) were utilized to map and analyze project data as needed. Cramer Fish Sciences led pre-project biological monitoring, environmental permitting (NEPA/CEQA, CDFW, Section 401 and 404, cultural resources, State Lands Commission), provided biological rationale for the project design, and perform pre- and during-construction biological monitoring. Vegetation Ecologist Rachel Hutchinson led vegetation impact analysis, planting plan design and vegetation monitoring efforts.

Learn more about this project at hallwoodproject.org.

Typical cross sections for existing and proposed conditions showing created habitats such as seasonal side channels and vegetated floodplain areas.

 


This video provides a bit of history of the project. Watch and learn how the hydraulic mining during the California Gold Rush played a part in the need for this project, and how the project team is turning that environmental legacy into a multi-benefit collaboration.