Department of Water Resources Home

Yolo Bypass


sutter bypass

Environmental Services

Dean Messer, Chief

3500 Industrial Blvd.
West Sacramento, CA 95691
(916) 376-9699

Mailing Address:
P.O. Box 942836
Sacramento, CA 94236-0001



Yolo Bypass Links

What is the Yolo Bypass?

photo of Bypass Scour Pond. Photo Credit: Francesca Nurmi

The approximately 69,000-acre Yolo Bypass is the largest floodplain of the Sacramento-San Joaquin Delta. The Yolo Bypass serves as the key flood conveyance facility to protect adjacent cities and land areas in Sacramento, Sutter, and Yolo counties from flooding. The Bypass also serves as an important area for wildlife-compatible farming, waterbird habitat, wildlife-based recreation, and education. It provides habitat for hundreds of native plants, fish, birds, and other wildlife species, including migratory birds along the Pacific Flyway and fish that migrate from the ocean to spawn and rear in areas throughout the Sacramento River watershed.

Migrating salmon, steelhead, and sturgeon rely on a series of environmental cues, such as water flows, to guide them from the ocean to their spawning grounds. However, the levees and other water control structures in the Yolo Bypass alter these flows considerably. The altered flows often lead migrating fish astray, which may result in them never reaching their spawning grounds. In addition, land uses have resulted in physical barriers to fish migration.

Studies of the Yolo Bypass and Cosumnes River floodplains have shown that seasonal floodplain habitats are an important factor in juvenile Chinook Salmon growth. The Bypass is only accessible to young salmon when the Sacramento River stage rises above the height of the Fremont Weir, typically during high flows in winter and early spring.