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Severe erosion of the Lake Oroville flood control spillway was observed on February 7, amid a series of atmospheric river storms that rapidly filled the reservoir. On February 11, the emergency spillway at Lake Oroville was used for the first time in its 49-year history. Erosion at the base of the spillway triggered the evacuation of nearly 200,000 people downstream on February 12.

Since then, crews have been working 24 hours a day to repair erosion areas, anchor the flood control spillway, and excavate more than one million cubic feet of debris that piled up at the base of the spillway. Hyatt Powerplant, which was temporarily shut down due to high water levels in the diversion channel, was restarted on March 3, with five units operating on March 10.

Full state, federal, and local resources have been 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, 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.

On April 17, 2017 DWR awarded a contract to Kiewit Infrastructure for repair work on Lake Oroville's spillways. Below are the three bidders, their bid amounts and a link to their bid documents.

Kiewit Infrastructure West Co. $275,443,850
Barnard Ames JV: $276,965,690
Oroville Dam Constructors: $344,129,100

Plans Under Design

DWR is implementing a recovery plan to ensure that by November 1, 2017, a system is in place that can safely accommodate heavy inflows at the Feather River watershed and Lake Oroville next winter. DWR, partner agencies, and contractors will be working around the clock to meet that objective.

The complete recovery or replacement of both damaged spillway structures will be done in multiple phases. The plan is to restore the gated flood control spillway to a capacity almost twice it highest historical outflow, up to approximately 270,000 cubic feet per second (cfs).

Read more about the Oroville Spillway Recovery Plan.


Governor’s April 6 Executive Order and Environmental Considerations

The primary intent of the April 6 Governor’s Executive Order is to protect public safety while permitting a swift recovery of the spillways before the upcoming wet season. Although the Order suspends specified state requirements, including compliance with the California Environmental Quality Act (CEQA), the spillway recovery team at the Department of Water Resources (DWR) has worked closely with state and federal regulatory agencies, including the Department of Fish and Wildlife (DFW) and the federal National Marine Fisheries Service. DWR will, as reasonably as possible given the urgent situation, continue to comply with existing requirements to protect the environment and implicated natural and cultural resources.

These environmental regulatory requirements have not slowed down or otherwise interfered with the emergency response or spillway recovery effort. At no time during this period did the DFW or other regulatory agencies impair any public health or safety decisions made by DWR or local law enforcement. Decisions about how much water to release from the damaged spillway were based on several factors, none of them related to fish. Instead, the factors at play included forecasting of storm conditions and resulting inflows, uncertainty about how the damaged spillway would perform, and the need to preserve the spillway for the remainder of the rainy season.

Environmentally Protective Actions Taken to Date:

Feather River Fish Hatchery – DFW relocated approximately two million spring-run Chinook salmon (listed as threatened under the federal and state Endangered Species Acts) from the hatchery downstream of Oroville Dam. DFW was able to move 100 percent of the hatchery spring-run fish out of harm’s way. They were also able to move approximately four million fall-run Chinook salmon, about 75 percent of the hatchery fish. In addition, approximately one million steelhead eggs and yolk sac fry that were unable to be relocated, and an estimated 1.7 to three million fall-run Chinook salmon, remained at the Feather River Hatchery. The steelhead eggs and fry were put on a mixture of river water and dechlorinated municipal water. The fall-run Chinook that remained at the Feather River Hatchery were kept in raceways, using an ad hoc engineering and water movement system CDFW created.

Fish Rescue Actions – DWR, DFW, and federal fish agencies completed several days of fish rescue actions on the Feather River to recover fish stranded as a result of rapidly changing flow conditions. Between February 27 and March 2, this coordinated, multi-agency effort deployed as many as 12 boats and 20-50 staff on the river. These staff rescued and relocated approximately 3,857 fish, including steelhead, fall-run Chinook salmon, spring-run Chinook, winter-run Chinook, sculpin, sucker, and lamprey. Observed mortality on the river was approximately 102 dead fish.

Ongoing Coordination – State and federal agencies have been and will continue to coordinate to manage and protect tribal, wildlife, and environmental concerns. This effort includes a tribal monitor and project-specific cultural site assessments, as well implementation of stormwater management and dust mitigation plans.

For the most up to date information on the Oroville spillway incident:

Most of our press briefings were broadcast live and can be found on Facebook. They'll be available on YouTube by the end of April 2017. You can also view other Oroville spillway incident videos and photos.

The press briefing on April 13, 2017, addressed reoperation of flood control spillway and recovery projects.

The press briefing on April 6, 2017, addressed recovery projects and emergency response.