In February 2017, a series of events led to the first-ever activation of the emergency spillway at Oroville Dam. Because of unanticipated levels of erosion downstream of the emergency spillway and concerns about the stability of the control structure, the Butte County Sheriff issued an evacuation order on February 12th at 4:21 PM for the areas downstream of the dam. Shortly thereafter, Yuba County and Sutter County issued similar warnings. It is estimated that approximately 188,000 people were affected by these evacuation orders. The U.S. Army Corps of Engineers (USACE) in cooperation with Gannett Fleming, Inc. conducted research on the public warnings issued during the Oroville incident and subsequent evacuations as part of an effort to collect and analyze data on: 1. The timing of the decisions to order public evacuation warnings and the flow of information between engineers and monitoring officials, 2. The method and timing of the dissemination of public warnings including the diffusion or warning by various communication channels, and 3. The interpretation and response of the public to those warnings. Interviews were conducted with emergency managers from all three affected counties as well as officials from the California Department of Water Resources. Data were also obtained from a statistically representative sample of the affected public. This paper focuses primarily on lessons-to-be-learned from the Oroville incident related to emergency planning, management, and response efforts. The findings from these studies will be incorporated into risk assessment models used in assessing the impacts of dam and levee failures on a national basis.
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