DWR Certifies Final EIR for Delta’s Largest Tidal Habitat Restoration Project


The habitat surrounding the future location of the Lookout Slough Tidal Restoration Project, located in the Cache Slough complex within the southern part of the Yolo Bypass in Solano County on October 13, 2020.

The habitat surrounding the future location of the Lookout Slough Tidal Restoration Project, located in southern part of the Yolo Bypass in Solano County on Oct. 13, 2020. DWR/2020

The Department of Water Resources (DWR) has moved one step closer to starting construction on the Delta’s largest multi-benefit tidal restoration and flood improvement project – Lookout Slough (LOS).

The final Environmental Impact Report (EIR) has been released and certified, clearing the project to move forward with completing the California Environmental Quality Act (CEQA) process and getting approvals for final construction permits.

As part of its ongoing commitment to restore Delta ecosystems, DWR has worked through an innovative public-private partnership with Ecosystem Investment Partners (EIP), a national company specializing in quality ecological restoration and conservation, to plan and design this large-scale multibenefit project.

“Lookout Slough demonstrates that projects with a bold vision for the future of the Delta are possible” said Kris Tjernell, DWR’s Deputy Director of Integrated Watershed Management. “This effort aims to achieve both habitat restoration and flood risk reduction goals on a regional scale, while protecting local sustainability. We celebrate this milestone and look forward to continuing the creative and thoughtful planning with our partners to realize these benefits on the ground.”

Lookout Slough is located in unincorporated Solano County, near the border of Yolo County. It is adjacent to additional tidal habitat restoration efforts being implemented by DWR, including Yolo Flyway Farms and Lower Yolo Ranch, to create a contiguous tidal wetland restoration complex spanning 16,000 acres in the Cache Slough region of the Sacramento-San Joaquin Delta. Once completed, Lookout Slough will be the Delta’s largest single tidal habitat restoration project to date.

The project will restore approximately 3,000 acres of tidal wetland in the Cache Slough region, creating habitat that is beneficial to native fish and wildlife. In addition to restoring tidal wetlands, the project will also create a new setback levee to provide residents in the surrounding area greater flood protection.

The new setback levee will meet objectives of the Central Valley Flood Protection Plan and the tidal restoration will provide a healthy food web and other benefits to important listed species, including delta smelt, giant garter snake and other native salmonids.

The restoration of tidal wetlands will work by allowing breaches in the existing Yolo Bypass West Levee along Shag Slough. The new setback levee will provide 100-year flood protection with additional height for climate change and sea level rise resiliency.

The Draft EIR was released for public review and comment by DWR in December of 2019 and a public meeting was held in January 2020 in Dixon.

Under CEQA, an EIR must be prepared whenever there is evidence that a project may impact the environment - including recreation, agricultural, water quality, or air quality.

“The final EIR shows the project meets all goals and objectives, and has no significant environmental impacts,” said Bonnie Irving, DWR project manager. “We are on track to start construction in 2021 and completing the project in 2023.”

During the EIR process, DWR completed a regional salinity study to analyze potential impacts of the project on water quality. The findings from the regional modeling study, which include other planned and completed restoration efforts, showed the project will stay within compliance of current water quality standards.

DWR was also able to utilize non-traditional mitigation measures to help upgrade adjacent dry pasture to prime agricultural land by adding irrigation. 

Lookout Slough is part of the California EcoRestore initiative to advance at least 30,000 acres of critical habitat restoration in the Delta. This project will partially fulfill DWR’s 8,000-acre tidal habitat restoration obligations pursuant to the U.S. Fish and Wildlife Service (USFWS) Delta Smelt Biological Opinion (BiOp) and is consistent with the National Marine Fisheries Service (NMFS) Salmonid BiOp and California Department of Fish and Wildlife Incidental Take Permit for long-term coordinated operations of the State Water Project (SWP) under DWR’s Fish Restoration Program.

“With the creation of 3,000 acres of tidal wetlands habitat, this multi-benefit project is vital to ensure DWR meets its environmental obligations for continued operations of the SWP,” said Ted Craddock, DWR’s Deputy Director of the SWP.This project marks a significant step towards balancing the needs of delivering water to millions of Californians through the SWP and being good stewards of the environment.”

Funding for the project is provided through two separate sources based on specific benefits. The habitat restoration objectives of the project will be funded by the SWP and State Water Contractors ($97,000,000), and the flood protection objectives will be funded by Proposition 1 – for multi-benefit and systemwide flood improvements ($21,865,000).

The project is expected to be complete by the end of 2023, with long term maintenance and biological monitoring continuing post construction.

View our photo gallery for pictures of the Lookout Slough project’s location and terrain.