Oroville Spillway Repairs: General Overviews. Select the image to view it as a high-resolution PDF.
On February 7, erosion was noticed on the flood control spillway located adjacent to the Lake Oroville Dam. DWR temporarily stopped outflow from the spillway to investigate the erosion. After testing and evaluation DWR resumed outflow from the flood control spillway to account for rising reservoir levels. Crews also began preparing for use of the emergency spillway by clearing trees, rocks, and other debris from the hillside where that water would flow. On the morning of Saturday, February 11, reservoir levels exceeded 901 feet and flowed over the emergency spillway for the first time in the reservoir’s history. This caused erosion to the hillside below the emergency spillway. On Sunday afternoon, the Unified Command – consisting of DWR, CalFIRE, and the Butte County Sheriff – determined that erosions caused a threat to public safety and the Sheriff issued mandatory evacuation orders for the area. To reduce lake levels, DWR increased flows down the flood control spillway to 100,000 cfs. Water stopped flowing over the emergency spillway early Monday morning. Mandatory evacuation orders were reduced to a warning on Tuesday, February 14. Reservoir levels continue to drop and crews work 24 hours a day to make repairs on the area below the spillway, access roads, and various eroded areas created by emergency spillway runoff. Due to ongoing work, a Temporary Flight Restriction for aircraft, including drones, was enacted for the area. DWR is aggressively monitoring the status of the dam, spillways, Hyatt Power Plant, related structures, and progress of repair activities.