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Lake Oroville Spillway Incident: Timeline of Major Events February 4-25. Select the image to view it as a PDF.

Oroville Spillway Incident Overview

On February 7, erosion was noticed on the flood control spillway located adjacent to the Lake Oroville Dam. Department of Water Resources temporarily stopped outflow from the spillway to investigate the erosion. After testing and evaluation, outflow resumed from the flood control spillway to account for rising reservoir levels. Crews also began preparing for use of the emergency spillway.

On February 11, reservoir levels exceeded 901 feet and flowed over the emergency spillway for the first time in the reservoir’s history. This caused erosion to the hillside below, causing a threat to public safety and the Sheriff to issue mandatory evacuation orders. Governor Brown immediately declared a state of emergency and the Governor’s Office of Emergency Services activated the State Operations Center to its highest level. To reduce lake levels, flows were increased down the flood control spillway and water stopped flowing over the emergency spillway February 13. Governor Brown met with emergency response officials and requested a Presidential Emergency Declaration – a request that was quickly approved.

Mandatory evacuation orders were reduced to a warning on February 14. Reservoir levels continue to drop and crews work 24 hours a day to make repairs on the area below the spillway, access roads, and various eroded areas created by emergency spillway runoff. The lake levels are significantly lower and the lake continues to have room for additional storm water inflows.

On February 22 – with a break in the weather and the situation in Oroville stabilizing – the Governor visited the Incident Command Post and surveyed the regional flood control system, including areas recently impacted by flooding.

Full state, federal, and local resources have been marshaled to help manage Lake Oroville operations, assess the problem and fix it rapidly. Dam experts with the U.S. Army Corps of Engineers, Federal Energy Regulatory Commission, the state Division of Safety of Dams and independent dam safety engineers remain actively engaged in managing the situation.

Public safety remains the top priority. The spillways are a separate structure from the dam itself, which is safe. Work is being done around the clock and will continue to be expedited through the summer to ensure the spillways are safe by the next flood season.

For Current Information on the Situation
Additional Resources

Overview of Repairs

Lake Oroville Spillway Repairs: General Overview February 21, 2017. Select the image to view it as a PDF.