Page - 33 - in Book of Full Papers - Symposium Hydro Engineering

Oroville and areas downstream is ordered. This is NOT A Drill. This is NOT A Drill. This is NOT A Drill. This message was disseminated using social media, local radio and television, and the Blackboard notification system (described further in Section 4.2.1). The Sheriff also ordered the deputies in Butte County to go to the neighborhoods at risk and announce the evacuation order over the public address system in their police vehicles. 3.5.2. 4:35 pm: All Three Counties at Risk. The National Weather Service in Sacramento released the following statement at 4:35 pm on February 12, 2017 via Wireless Emergency Alerts (WEA) to everyone in the entire three-county area at risk. “The National Weather Service in Sacramento has issued a Flash Flood Warning for a dam failure in south central Butte County in Northern California. Until 4:15pm PST Monday. At 4:19pm PST, dam operators reported a hazardous situation is developing with the Oroville Dam auxiliary spillway. Operation of the auxiliary spillway has led to severe erosion that could lead to a failure of the structure. Failure of the auxiliary spillway structure will result in an uncontrolled release of floodwaters from Lake Oroville. In response to this developing situation, DWR is increasing water releases to 100,000 cubic feet per second. Immediate evacuation from the low levels of Oroville areas downstream is ordered. From Oroville to Gridley...low level areas around the Feather River will experience rapid river rises. This is not a Drill. This is not a Drill. Repeat this is not a drill. Locations impacted include Oroville, Palermo, Gridley, Thermalito, South Oroville, Oroville Dam, Oroville East and Wyandotte. Turn around, don't drown when encountering flooded roads. Most flood deaths occur in vehicles. Move to higher ground now. Act quickly to protect your life.” 3.5.3. 5:33 pm: Yuba County. The Yuba County Office of Emergency Services issued the following warning message to people in Yuba County at 5:33 pm on February 12, 2017. “ALERT- ALERT-ALERT –- Yes, an evacuation has been ordered. All of Yuba County on the valley floor. The auxiliary spillway is close to failing. Please travel safely. Contact family and friends. Help the elderly. Take only routes to the east, south, or west. DO NOT TRAVEL NORTH TOWARD OROVILLE!!!!!” At 5:48 pm, the Marysville Police Department confirmed that a mandatory evacuation for the City of Marysville and Yuba County was in effect. Then at 6:08 pm it was stated that: “Evacuation for Yuba includes Hallwood, Marysville, Olivehurst/Linda and Plumas Lake due to potential failure of Oroville Dam spillway.” 33