Yolo Bypass Comprehensive Study

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Yolo Bypass Comprehensive Study

The Sacramento River Basin is California’s largest, key watershed that is integral to a water system that serves the most populous state in the Nation and the fifth-largest economy in the world. Within its footprint sits the state’s capital, Sacramento, a metropolitan area with one of the highest residual flood risks in the Nation.

Background: Federal, state, and local governments and stakeholders have worked ceaselessly for more than a century to develop water resource management solutions, particularly with regard to flooding in order to protect life and property in the region. These efforts have enabled residential, industrial, commercial, and agricultural communities and businesses to safely develop, grow, and thrive, but these positive changes also call for action to further reduce flood and life safety risk, restore wildlife habitat and natural ecosystems, improve passage for fish, and improve water supply reliability.

Complexities: The complexities of the challenges facing the Sacramento River Basin are only increasing as the state experiences more dramatic swings between flooding and drought. Debates about comprehensive management solutions are also occurring within a context where escalating needs for the same land, water, and environmental resources are manifesting themselves within the same geographic region.

Authority: Through the Water Resources Development Act of 2020 (WRDA), Congress directed the United States Army Corps of Engineers (USACE) to conduct a Comprehensive Study of the Yolo Bypass system to evaluate flood risk management, ecosystem restoration, water supply, and recreation. The authorization also directed USACE to consult with the State of California, applicable Federal, State, and local agencies, Tribal nations, non-Federal interests, the Yolo Bypass Cache Slough Partnership, and other stakeholders in conducting the Study.

Recommendations: The study will develop recommendations which may include:

Additional monitoring and adaptive management of the existing Yolo Bypass System;

Potential follow-on activities to design and construct flood risk management and/or aquatic ecosystem restoration features (including potential modifications to the existing system); and/or

Potential recommendations for future feasibility studies that could lead to the construction of new water resources development projects that complement the existing Yolo Bypass System authorized purposes.

Sponsors: The Study’s non-federal sponsors are the Central Valley Flood Protection Board (CVFPB) and the Sacramento Area Flood Control Agency (SAFCA). A Memorandum of Understanding between the CVFPB and the California Department of Water Resources (DWR) identifies that DWR’s Division of Flood Management is performing project management on behalf of the CVFPB, including managing the State’s financial contribution to the Study.

Importance of the Yolo Bypass Study Area

Situated between the Fremont Weir in the north and the Sacramento-San Joaquin Delta (Delta) in the south, the Yolo Bypass is a 40-mile-long federal flood management facility that plays a crucial role in protecting the region from flooding. It is also central to a significant agricultural economy, a critical water supply delivery system, and an ecosystem of national significance.
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Flood Risk Management

The Yolo Bypass is the heart of the Sacramento River Flood Control Project and conveys 80% of Sacramento River watershed flows during floods, reducing risk to 950,000 people, 284,000 structures, and $150 billion in critical infrastructure.

Ecosystem of National Significance

The bypass supports 22 Threatened and Endangered species and is a key stopover on the Pacific Flyway supporting millions of waterfowl annually. The entire bypass, and particularly the 16,800-acre Yolo Bypass Wildlife Area, provides habitat for over 200 bird species., The Fremont Weir Wildlife Area provides grassland and riparian habitat. In addition, the bypass is uniquely situated along the migration corridor for federally protected salmon, steelhead, and sturgeon.

Agricultural Economy

The Yolo Bypass contains approximately 47,000 acres of agricultural land, making it an important contributor to the nation’s food supply and economy. The surrounding counties of Yolo, Solano, and Sacramento have more than 900,000 acres of farmland in production within the area served by the Sacramento River Flood Control System.

Water Supply Delivery System

Portions of the Yolo Bypass serve as mitigation areas for the State Water Project and Central Valley Project, which provide drinking water to 27 million Californians and irrigation to 2.5 million acres of agricultural land.

History and Cultural Significance

Congress designated the Sacramento-San Joaquin Delta as a National Heritage Area (NHA) in 2019. The Delta Protection Commission is the local coordinating entity for the NHA.

Recreation

The Yolo Bypass provides local and regional recreation, tourism, and environmental education opportunities including hiking, fishing, hunting, wildlife viewing, and boating. There are three wildlife areas managed by the California Department of Fish and Wildlife: Yolo Bypass Wildlife Area, Fremont Weir Wildlife Area, and Sacramento Bypass Wildlife Area.

Study Schedule

Feasibility Cost Share Agreement - Sept. 25, 2023
Alternatives Milestone Meeting - May 10, 2024
Tentatively Selected Plan Milestone - Dec. 11, 2026
Draft Report Released for Review - Feb. 23, 2027
Command Validation Milestone - June 22, 2027
Final NEPA Review - Summer 2028
Transmittal of Final Report Package - Oct. 20, 2028
Chief of Engineers Report - March 20, 2029

History

Prior to the federal investment in flood control, and before extensive settlement in the area (pre- 1849), the Yolo Basin was one of many naturally occurring flood basins in the Lower Sacramento River system. The Yolo Basin was primarily natural land, with limited development and high habitat value. It also has a deep history of cultural significance to 13 Native American Tribes.

As part of the Sacramento River Flood Control Project, the Yolo Basin was reclaimed and developed primarily as farmland. Over the last 100 years, it has functioned primarily as a single-purpose flood-control facility, with other uses largely restricted.

Next Public Engagement

Public Outreach Virtual Meetings
Monday, July 7, 2025
10:30 a.m. and 6:30 p.m.

Meeting Invite/How to Join Virtual Meeting
Presentation Slides
Fact Sheet
Narrated Presentation:

Latest News

PHOTOS: Federal, state, local leaders sign Feasibility Cost Share Agreement to initiate Yolo Bypass Comprehensive Study (Sept. 25, 2023)

Documents

Study Fact Sheet (July 2025)

2023 Interim Status Report (December 2023)

Review Plan Documents
Approval Memo (October 2024)
Review Plan (September 2024)
Endorsement (June 2024)

Contact Information

For more information on the
Yolo Bypass Comprehensive Study,
please contact us at the following

Phone:
916-557-5100

E-mail:
CESPK-YOLOBypass@usace.army.mil

Mailing Address:
U.S. Army Corps of Engineers
1325 J Street, Room 1640
Sacramento, CA 95814