Monitoring of Yolo and Sutter Bypasses for Fish Stranding and Rescue Operations
During high outflow events, the Sacramento River’s floodwaters overtop Fremont and Tisdale weirs, resulting in inundation of the Sutter and Yolo Bypasses. These flows attract upstream migrating fish from the Sacramento River into the Yolo Bypass at the mouth of the Cache Slough complex near Liberty Island. However, when floodwaters recede, numerous fish can be trapped in the downstream of the Fremont Weir splash basin and in downstream scour ponds, pools, and swales and are unable to return to the Sacramento River. CDFW staff has conducted numerous fish rescues at the Fremont Weir, Yolo Bypass and Tisdale Weir, and other flood control structures, saving tens of thousands of fish including numerous individuals of the aforementioned listed species.