Oroville Spillways Incident Background

A steady barrage of storms in early 2017 resulted in serious damage to the Lake Oroville spillways. This included concrete on the lower chute of the main flood control spillway and erosion in the areas on the hillside beneath the emergency spillway.

Over the next several months of winter storms, DWR successfully managed outflow and Lake Oroville levels while crews worked 24 hours a day to repair erosion areas, remove debris from the diversion pool, and construct and improve access roads. DWR actively monitored the status of the Oroville Dam, the gated flood control and emergency spillways, Hyatt Powerplant, related structures, geologic conditions, while making plans for the reconstruction of the main and emergency spillways. 

Record Rainfall

January and February were the wettest in 110 years of Feather River hydrologic record. Lake Oroville received an entire year's average runoff of 4.4 million acre-feet in about 50 days during those two months. More than 3.6 million acre-feet volume of reservoir inflow (equivalent to the entire storage capacity of Lake Oroville) was safely released from Lake Oroville through the significantly damaged gated flood control spillway.

Collaborative Operations

Full state, federal, and local resources were marshaled to help manage Lake Oroville operations, assess the problems, and rapidly fix them. Dam experts with the U.S. Army Corps of Engineers, Federal Energy Regulatory Commission Dam Safety, the California Division of Safety of Dams, and independent dam safety engineers remain actively engaged in managing the situation. Public safety is DWR's top priority.

Timeline of Events February 7-March 17, 2017

View day-by-day accounts of the Lake Oroville spillway incident below. You can also refer to our news releases for more detailed information.

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For press inquiries,
Email: OrovillePIO@water.ca.gov
Call: (916) 651-2440