The Fremont Weir Adult Fish Passage Modification Project

Allen Young, DWR – At 59,000 acres, the Yolo Bypass can hold four times the capacity of water as the Sacramento River. The primary trigger for river releases into the bypass is the Fremont Weir, a 1.8-mile concrete wall that automatically overtops when the Sacramento River reaches a designated high-water mark. Water flows over the weir every two out of three years on average. Built in 1924 by the U.S. Army Corps of Engineers, the Fremont Weir has been hailed as a simple yet impressive feat in sustainable flood protection and engineering. The Fremont Weir Adult Fish Passage Modification Project is one of many restoration and infrastructure improvements within the Yolo Bypass aimed at boosting salmon survival rates. Other projects include the Wallace Weir Adult Fish Rescue Facility, the Yolo Bypass Salmonid Habitat Restoration and Fish Passage Project, and the Lower Putah Creek Restoration Project. (more)