The Yolo Bypass is one of two flood bypasses in the Sacramento Valley located in Yolo and Solano Counties. It protects Sacramento and other riverside communities from flooding through a system of weirs. These weirs connect the bypass to the Sacramento River as well as to various local creeks where the water is eventually drained into the Sacramento-San Joaquin River Delta.
Sacramento experienced several severe floods prior to construction of the bypass. During wet years, the bypass can be full of water. The main input to the bypass is through the passive Fremont Weir, where water spills over into the bypass if it reaches the 33.5-foot crest. Downstream, the Sacramento Weir, just north of the city of West Sacramento, can also be opened to divert additional waters to protect Sacramento and West Sacramento if needed. The bypass ends a few miles north of Rio Vista in the Liberty Farms area, where the bypass joins first Prospect Slough and then Cache Slough adjacent to the connection of the Sacramento Deep Water Ship Channel. Cache Slough then reconnects with the Sacramento River just North of Rio Vista.
The Yolo Bypass contains the Vic Fazio Yolo Wildlife Area and was the largest public/private restoration project west of the Florida Everglades. It forms a valuable wetland during many months. In the summer, the bypass is used for agriculture.
The bypass separates the city of West Sacramento from Davis, California. It is crossed by the Yolo Causeway, a long highway bridge on Interstate 80. To the north, Interstate 5 also crosses the bypass on the Elkhorn Causeway.