DWR Now Using 2018/2019 Flood Operations Plan at Oroville


Lake Oroville

A drone provides an overview of the recently completed Lake Oroville main spillway during Phase 2 of the recovery effort at the Butte County, California site.

As construction ramps down at Oroville’s main and emergency spillways in 2019, the California Department of Water Resources (DWR) is operating the reservoir under the new 2018-2019 Flood Operations Plan to safely manage operations during the winter months. The Plan ensures flood protection for downstream communities while meeting downstream water deliveries and environmental requirements.

The 2018-2019 plan builds off the prior flood operations plan that was put in place for the 2017-2018 winter, when DWR had completed the first phase of reconstruction on the main spillway. During that phase, the main spillway chute was temporarily reconstructed to a design of capacity of 100,000 cubic feet per second (cfs). DWR successfully completed the second phase of reconstruction on Nov. 1, 2018, and the main spillway is now fully restored to handle flows of up to 270,000 cfs.  

DWR’s preferred maximum flow down the main spillway is 150,000 cfs – the operational capacity of downstream levees. The ability to release 150,000 cfs allowed DWR to include adjustable flood management storage targets, which have been updated in this new Flood Operations Plan to take into account both dry and wet ground conditions. Last year’s plan used a fixed reservoir level restriction due to the interim construction of the Oroville main spillway. Other key elements of the plan include enhancements to the flood pool to avoid use of the emergency spillway and accounting for scheduled maintenance at Hyatt Powerplant throughout the winter of 2019.

The 2018-2019 Plan accounts for minor ongoing construction work on Oroville’s main and emergency spillway and accounted for the completion of the Nov. 1 public safety construction milestone for the main spillway. DWR and its construction contractors met the milestone early by completing all concrete placements in late October of 2018.

Like the Flood Operations Plan developed for 2017-2018 winter, DWR provided this year’s plan for review to the United States Army Corps of Engineers, the California Division of Safety of Dams and the Federal Energy Regulatory Commission before it was finalized.

The 2018-2019 plan continues to meet the United States Army Corps of Engineers’ 1970 Lake Oroville Flood Water Control Manual requirements.

Liza Whitmore, Information Officer, Public Affairs, Department of Water Resources
530-534-2317 | Elizabeth.Whitmore@water.ca.gov