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Tidal Stream Restoration at the Lookout Slough Project

Chuck Davis, PE, CFM
Project Manager
Beaver Creek Hydrology, LLC
Lexington, KY

David Urban, PE
Managing Director
Ecosystem Investment Partners
Baltimore, MD

Ecosystem Investment Partners (EIP) and the California Department of Water Resources (DWR) worked together to develop a multi-benefit project in the Lower Yolo Bypass known as the Lookout Slough Restoration Project. Upon completion, the project will create more than 3,000 acres of habitat for listed and vulnerable native species in Solano County and will reduce flood risks consistent with the 2017 Central Valley Flood Protection Plan Update. The project entails breaching and degrading an existing levee along the west bank of the Yolo Bypass to provide tidal access to the 3,000-acre site, creating channel habitat for aquatic wildlife species and upland habitat for terrestrial wildlife species, and constructing new setback levees and strengthening existing levees on site to protect properties further inland that had previously been protected by the Yolo Bypass west levee. When completed, the Project will provide upland, tidal, subtidal, and floodplain habitat for Delta Smelt, Longfin Smelt, Steelhead Salmon, Splittail, Giant Garter Snake and other species. The Project will constitute the largest habitat creation project in California.

Over twenty miles of tidal channels were designed to create tidal, subtidal, and floodplain habitat features and to facilitate tidal access throughout the 3,000-acre project site.  Beaver Creek Hydrology assisted in channel design and layout for the project.  While many tidal restoration projects use a tidal prism analysis or watershed area to determine channel geomorphology and size, the design team determined that channel sizing for this project was more adequately related to levee breach size.  Detailed hydrodynamic modeling was used to confirm channel sizing for various combinations of tidal and riverine flooding conditions.  Further, results of hydrodynamic modeling were used to analyze the transport of planktonic food within the site for the Delta Smelt, a critical species for the design and permitting of the project.  Volumetric flow rate and channel dimension were thus related to the breach size, and a proprietary mathematical model was used to generate three-dimensional channel bathymetry surfaces for final design and construction.  This paper will provide an overview of the design approach for tidal channel restoration at the Lookout Slough Restoration Project.