Page - 48 - in Book of Full Papers - Symposium Hydro Engineering

Major reservoirs were operating based on regulatory flood control curves and were releasing flood flows by design. Prior to February 7, 2017, DWR had already activated the Joint State-Federal Flood Operations Center (FOC) in Sacramento. This was due to heavy precipitation causing high water conditions in many California streams and rivers, resulting in elevated flood threats throughout California. By February 7, over 145% of normal precipitation had occurred over the Feather River Basin. A purpose of the Oroville Dam facility is to manage flood flows by routing inflows through the reservoir and the FCO Spillway according to the prescribed operations plan and regulatory requirements. The FCO Spillway began releasing 850 m3/s (30000 ft3/s) on February 3 and then the release was increased to 1416 m3/s (50000 ft3/s) on February 6, 2017. On February 7, and within standard operating criteria, FCO Spillway release was increased to 1530 m3/s (54000 ft3/s) due to forecasts predicting additional heavy precipitation. After the FCO Spillway flow was increased on February 7, unusual flow patterns and brown water were observed approximately half way down the chute. The FCO Spillway was immediately shut down to observe the chute condition (Fig. 3). Initial assessments of the FCO Spillway chute damage were made and additional technical resources were brought in to evaluate potential mitigation and protective measures that might be implemented. Forecasts were predicting significant reservoir inflows in the coming days. The emergency warranted that DWR activate the Oroville Dam Emergency Action Plan (EAP) to ensure that local, State, and Federal agencies were notified of the current incident. Fig. 3 – Damage to FCO Spillway chute on February 7, 2017 Over the next hours and days, critical technical and regulatory teams arrived at the facility to assist with the assessment and development of mitigation measures, analyze risks, implement contingency plans, and update local agencies and the media. State and Federal regulatory agencies along with other specialized consultants were some of the first to arrive at the site to engage in these activities. 48