Lake Oroville Spillway Incident: Timeline of Major Events February 4-25 Oroville Spillway Public Info Line: (530) 538-7826 ➊ February 7: As water releases from the flood February ➊ control spillway ramp up to 54,500 cubic feet per 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 second (cfs), in anticipation of inflows expected from rainfall, DWR employees notice an unusual Cubic feet per second (cfs) Inflows to Lake Oroville reach flow pattern. Spillway flows stop for investigation. 180,000 190,435 cfs, significantly Engineers find large area of concrete erosion. Between higher than forecasted ➋ February 8: DWR begins ongoing consultation with February 6-10, FERC and other dam safety agencies. DWR runs test 12.8 inches of rain Mandatory Flood Control flows down the damaged spillway, monitoring further 160,000 fall in the Feather Spillway erosion, and prepares for possible use of emergency River Basin evacuation outflows raised spillway. 24/7 emergency interagency operations order is to 100,000 cfs to centers activate to study and implement response issued ease pressure to flood control spillway and related structures, with 140,000 ➍ on Emergency ➋ ➌ careful study of weather forecasts. Spillway ➌ February 11: Inflow to Lake Oroville brings lake ➍ level above 901 feet. This engages the emergency 120,000 spillway for the first time in the history of the facility. ➍ February 12: Anticipated erosion begins to progress faster than expected at the base of the emergency ➐ spillway. The Butte County Sheriff’s Office issues 100,000 mandatory evacuation orders for the Oroville area. To Flood Control ➍ ➎ ease pressure on the emergency spillway, the flood Spillway control spillway outflow is increased to 100,000 cfs. inspection After several hours, inflows decrease and overflow 80,000 stops at the emergency spillway. Erosion to the ➊ ➑ emergency spillway hillside is assessed. INFLOWS OUTFLOWS ➎ February 13: DWR crews begin working around the 60,000 clock to repair the emergency spillway. Evacuation orders remain in effect. ➏ February 14: As the lake level continues to drop, the mandatory evacuation order is modified to an 40,000 evacuation warning. Crews continue working around the clock to repair the emergency spillway. An elevation of 850’ is targeted for lake level. 20,000 ➐ February 16: Flood control spillway flows are ➋ reduced below 100,000 cfs to facilitate the clearing of debris from below the spillway. Lake levels continue ➏ to drop. Construction to armor the emergency 0 spillway continues. ➐ ➑ ➑ February 18: Lake level down to 854 feet. Flood Lake level, in feet ➌ 02/12/2017: 03:00 am 902.59’ control spillway flows are reduced to 55,000 cfs. Barge construction begins in order to remove debris 900 from the diversion pool beneath the spillway. ➏ ➒ February 20: Lake Oroville elevation reaches 848.95 feet at 11 a.m. Repairs and preparations 880 continue around the clock. ➐ Cooperating Agencies: California Department of LAKE LEVEL ➒ Water Resources, Butte County Sheriff, CAL FIRE, 860 ➑ Oroville Police Department, Butte County OES, ➒ Oroville Fire Department, Butte County Public Works, 850’ elevation Oroville Hospital, Caltrans, California Highway Patrol, California State Parks, California Conservation Corps, 840 California National Guard, California Department of Fish and Wildlife, PG&E, Red Cross, Bureau of Indian water.ca.gov Affairs, CAL OES, USACE, FERC, FEMA 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 cdec.water.ca.gov/ For more imagery, see DWR Pixel Library February Source: CDEC reservoir.html.