Oroville Spillway Incident site banner

Frequently Asked Questions

Response & recovery

  • The purpose of the response effort was to ensure the safety of residents downstream and facilities related to the dam.
  • The objective of the recovery effort is to ensure that by November 1, 2017, the system can safely accommodate potentially heavy inflows from the Feather River watershed to Lake Oroville and subsequent releases from the Lake. Construction on the main and emergency spillway will continue into 2018
  • By November 1, DWR will remove and reconstruct 1,400 feet of the lower chute of the main spillway below where the erosion began and 600 feet of the upper chute above where the erosion first began. DWR will patch and add additional anchoring to the uppermost portion of the main spillway – 1,000 feet from where the gates are – this year and remove and reconstruct it during the 2018 construction season.
  • Also by November 1, we will construct an underground cut-off wall downstream of the emergency spillway which will provide additional assurance that if we ever need to use the emergency spillway again, its use will not jeopardize the integrity of the dam.
  • Construction will continue in 2018 to make final updates to both spillways.
  • The plans for upgrading the flood control spillway and the emergency spillway will use modern design and construction standards, while providing increased capacity to manage flows starting this winter.
  • Although final plans, project designs and cost estimates are still being developed, it is anticipated that the recovery costs will be more than $500 million, which includes the $275 million construction contract with Kiewit.
  • The $275 million awarded to Kiewit was based on a 60-percent design. It is normal for additional change orders (additional budget) to be added as the design becomes 100-percent final.
  • As a State Water Project (SWP) facility, repairs to the Lake Oroville spillways will be paid for by SWP contractors per the long-term water supply contracts for any costs not recoverable from federal grants or other sources.
  • DWR is working with CalOES to secure the maximum reimbursement allowable under FEMA's disaster assistance program for all eligible disaster related costs.
  • FEMA may cover 75 percent of the eligible emergency response and Oroville Dam complex repair costs. To date, it is estimated that over $500 million is identified for response activities and project repair costs.
  • Through consultation with DWR, partnering agencies and the Butte County Sheriff deemed it necessary for the safety of residents downstream.
  • Emergency response resources were not diverted to the fish recovery. The primary focus of any emergency response is always first and foremost to ensure the safety of residents.
  • The fish relocation was managed by California Fish and Wildlife Employees, not by DWR. The efforts to relocate fish were related to water quality issues and happened days before DWR resorted to using the emergency spillway.
  • The main spillway has been used 26 times since the dam was built in 1969 to safely release water from Lake Oroville. The number of times the spillway is used in a given year is dependent on precipitation and lake levels.
  • DWR is working to compile this number, which will include total jobs created for the emergency response and emergency recovery phases of the project.
  • Kiewit expects to employ 500 people by August. Most of these people are residents of Butte County and nearby counties, including Sacramento.
  • The Oroville Emergency Recovery Spillways project is a state project not subject to the NEPA statute that federal agencies must follow. NEPA does not apply to DWR but our federal partners will comply with NEPA.
  • $22.8 million as of the end of July 2017.
  • $8,641,755 million to the Department of Water Resources to reinforce the emergency spillway.
  • $14,166,303 million in federal funds for the clearing of 2.2 million cubic yards of debris and the removal of debris and sediment from the Feather River.
  • The funds are allocated through FEMA’s Public Assistance (PA) program for help clearing debris and emergency protective measures taken.
  • DWR will continue to submit requests for reimbursements from FEMA regarding the Lake Oroville spillways incident. This first payment is encouraging as we expect to receive additional reimbursements. We value our partnership with FEMA and Cal OES and look forward to working together on this important process of recovery at Lake Oroville.
  • The disaster declaration signed by President Trump on April 1, 2017 made FEMA’s PA program available to public entities and certain nonprofits in 42 designated counties. Since then, the state and FEMA have worked with local officials to identify damage, determine eligibility, develop project costs and deliver funding to assist in the recovery from the February storms.

Phone: 1-800-248-7026
Email: Oroville@water.ca.gov
Twitter: twitter.com/@CA_DWR
Facebook: facebook.com/CADWR
YouTube Channel: www.youtube.com/user/calwater
Lake Oroville Spillways Webpage: water.ca.gov/oroville-spillway

Safety & security

  • The Oroville Dam was never at risk and remains sound.
  • Seepage is normal for any earthen dam.
  • The green spot is a seasonal wet band of vegetation on the face of Oroville Dam. It is not a threat to Oroville dam.
  • It was noted during construction in 1966-67 before the reservoir was filled, and understood to be a result of rainfall percolating into the fill and perched on dirtier layers created during construction on the outside of the dam.
  • This is an assessment that was developed over 50 years ago, supported by decades of performance monitoring instrumentation, and concurred with by engineers observing the dam over time.
  • Lake levels are being managed by adjusting river releases on a day-to-day basis. DWR will manage observed and forecasted reservoir inflow with necessary releases to achieve a safe and reasonable lake level into the fall that takes into account the needs for public safety first and foremost. As for secondary purposes, consideration will be made for other important uses such as environmental flows and local and statewide water deliveries and recreation when possible. DWR cannot make a commitment to a specific lake level beyond ensuring it will be safe.
  • DWR must continue to meet regulatory environmental needs and contractual requirements for local and statewide water supply. In addition, DWR plans to target a lake level of around 700 feet by November 1 as a public safely safeguard going into next winter. So far this summer, inflow from snow melt is far less than forecasts anticipated. As such, DWR plans to begin slowly decreasing releases to keep the lake at safe operating levels throughout the summer that may also support recreational uses.
  • Public safety is the number one priority while construction is underway to rebuild the gated flood control spillway, also known as the main spillway, and the emergency spillway. To meet this public safety priority, DWR committed to lowering lake levels so the emergency spillway or main flood control spillway would not have to be used after May. At the request of the Federal Energy Regulatory Commission, DWR lowered lake levels between March and May to ensure water would not go over the emergency spillway. Additionally, FERC requested lake levels to be as low as possible by November 1, 2017.
  • Because of this, lake levels were lowered at a faster pace than in previous wet years, to ensure that construction could get underway in a timely manner while still safely managing inflows from the year's record precipitation and large snowpack.
  • Following rules and guidelines set by the Federal Energy Regulatory Commission (FERC), DWR evaluates all public documents related to the Oroville Emergency Recovery project to identify information regarding specific engineering, vulnerability, or detailed design that could be useful to a person in planning an attack on critical infrastructure. This information is deemed Critical Energy Infrastructure Information (CEII), and that information is redacted before the document is released publicly.
  • According to Federal Energy Regulatory Commission (FERC), CEII is specific engineering, vulnerability, or detailed design information about proposed or existing critical infrastructure that: (1) relates details about the production, generation, transportation, transmission, or distribution of energy; (2) could be useful to a person in planning an attack on critical infrastructure; (3) is exempt from mandatory disclosure under the Freedom of Information Act, 5 U.S.C. 552 (2000) and the California Public Records Act, per 16 USC 824o-1(d); and (4) does not simply give the general location of the critical infrastructure.
  • FERC’s regulations require the dam owner to designate its CEII documents submitted to FERC as CEII. In carrying out its responsibilities as the owner of Oroville dam, DWR acts in a manner to protect public interest and public safety.
  • DWR reviews the documents to identify if there is any sensitive information that could be used to put the public at risk. DWR makes the final decision on what needs to be labeled as CEII in documents that are sent to FERC.
  • Because dams such as Oroville Dam are critical infrastructure, DWR reviews all documents related to the dam to identify if they contain any sensitive information that must be kept confidential.
  • Information pertaining to proposed or existing engineering, vulnerability, and design may be considered CEII. DWR makes the final decision on what needs to be labeled as CEII in documents that are sent to the Federal Energy Regulatory Commission. It is FERC's policy for individual states to keep documents "confidential" if they are designated CEII by dam owners, in this case DWR.
  • FERC Part 12D reports are a long-standing part of the overall monitoring and inspection process of hydroelectric facilities and dams under the jurisdiction of FERC.
  • “A comprehensive assessment of the current health and long-term safety of the dam, much like a detailed physical examination by your physician.”
  • Part 12D is a section of the report the requires an Independent Consult to conduct a detailed review of the design, construction, performance, and current condition assessment of an entire dam facility.
  • Independent Consultants rely on a Potential Failure Mode Analysis (PFMA) and a Supporting Technical Information Document (STID) as well as visual inspections.
  • Independent Consultants also review previous FERC Part 12D reports and then make recommendations for action by the dam owner based on their observations and analysis. These actions can include everything from maintenance to increased monitoring.
  • DWR released FERC Part 12D reports to ensure all available information is available relating to maintenance and inspections.
  • During construction of Oroville Dam in the 1960s, DWR installed 56 twin-tube hydraulic piezometers upstream, downstream, within the dam’s core, and in the dam’s foundation. The piezometers as well as a seepage collection and monitoring system were installed to monitor and verify the expected water levels in the dam during construction, during the lake’s first filling, and those first few years thereafter.
  • Engineers installed the piezometers with the understanding that the monitoring devices had a limited lifespan and would no longer function after several years. Two piezometers within the dam’s core remain today that are currently monitored. However, these two piezometers will eventually become non-functional and no longer monitored.
  • The dam’s seepage collection and monitoring system remains fully functional and provides valuable information on seepage through the dam. The seepage collection system is designed to remain serviceable for the life of the dam.
  • In the fall of 2016, prior to the spillway incident, DWR initiated a study to analyze seepage and stability of the dam, which includes a thorough and thoughtful evaluation of all instrument data to date and future data needs.
  • The completed study will help DWR determine whether or not new piezometers or other instrumentation are appropriate. This includes assessing dam safety risk versus benefit, as installation of any instrumentation (e.g. piezometers) into the dam’s embankment could potentially create more risk to dam safety.
  • Any decision about piezometers would be reviewed and approved by the California Division of Safety of Dams and the Federal Energy Regulatory Commission as well as Independent Board of experts.
  • California’s inundation map program for dam failure is a responsibility of the Governor’s Office of Emergency Services (CalOES) and is handled specifically by the Hazard Mitigation Program.
  • The Cal OES Dam Inundation Mapping & Emergency Procedure (DIMEP) Program was established by Government Code §8589.5 in 1972 following a near failure of the Lower San Fernando Dam during the Sylmar Earthquake.
  • The inundation map for an Oroville Dam failure can be found at: http://www.caloes.ca.gov/HazardMitigationSite/Documents/Inundation%20Map%20for%20Oroville%20Dam%202016.pdf
  • Please note that this map does NOT represent a spillway failure, only a total Oroville dam failure.
  • The Forensic Team, a collection of internationally-respected scientists with dam safety and engineering expertise, continues its comprehensive assessment of the cause of the failure and we expect their report to be completed this fall.
  • We welcome additional analyses and studies and will ensure this report is shared with the Forensic Team.
  • Memos from the Board of Consultants and the Forensic Team are posted on our website: http://www.water.ca.gov/oroville-spillway/bocreports.cfm
  • Consistent with DWR policy and FERC guidelines, some of the memos were redacted to remove confidential information, called Critical Energy Infrastructure Information (CEII).
  • DWR will follow this same protocol for each subsequent report from the Board of Consultants, and for the Forensic Team’s report, which is expected this fall.
    • The Forensic Team is an independent group of experts charged with determining the actual causes of the spillway incident.
    • The Board of Consultants is an independent group of experts charged with advising on the design of the reconstructed spillways.

Infrastructure

  • DWR’s Division of Safety of Dams maintains an alphabetical list of all California dams and reservoirs. The list includes information including dam name, owner, county of location, year built, capacity, area, height, etc.
  • California has the “leading dam safety program in the nation” according to a peer review conducted by the Association of State Dam Safety Officials.
  • The first indication of erosion in the main spillway appeared on February 7, 2017. No significant concerns had been raised previously by the state, federal government, or any independent consultant regarding the adequacy, stability or structural integrity of the main or emergency spillway. All inspections of Oroville Dam and its spillways have concluded they are safe to operate. It is crucial that we bolster dam safety inspections in California and beyond. It is important that we identify and prevent future emergencies.
  • The cause of the main spillway failure is being investigated by the Forensics team, an independent team of internationally respected scientists and engineers. Their findings will be made public in a final report in the fall.
  • DWR is continually assessing Oroville Dam. Oroville Dam is formally inspected multiple times a year.
  • Twice a year, it’s inspected by DSOD. The last inspection by DSOD was conducted in August 2016. Oroville Dam is also inspected annually by the FERC Dam Safety Program. The most recent inspection by FERC was conducted in May 2016.
  • Oroville Dam is also inspected by an independent board of expert consultants every five years.
  • The most recent independent safety inspection was conducted in August 2014. All of these inspections of Oroville Dam and its spillways have concluded they are safe to operate.
  • Impacts are inevitable, we are doing our best to anticipate, plan, and communicate with residents of Oroville and surrounding communities about specific impacts and possible solutions and we will continue to do so.
  • DWR is also making every effort to collaborate with local agencies, businesses, and organizations to minimize – as much as is possible – construction impacts on the local economy and way of life.
  • Lake Oroville is open for business. DWR will provide regular updates on its ongoing work and on all activities over the coming months as construction ramps up through the summer.
  • DWR has updated its notification procedures and when possible, will be giving 24-hour notice to local maintaining agencies.
  • DWR is making this change based on feedback received at the Gridley public meeting held on April 27.
  • A Board of Consultants (BOC) is required by California Water Code (Division 3, Part 1, Chapter 3, Section 6056) for modifications to any dam owned by DWR. In addition, FERC requires a Board of Consultants to review and comment on repairs to dams. Therefore, the recovery of the Oroville spillways is being reviewed by the BOC. As is typical for all repairs and new construction for dams regulated by FERC, a BOC is required and has been engaged for the emergency response and recovery of the Oroville Dam spillways. DWR has engaged a five-member BOC for the emergency response and repairs of the Oroville Dam spillways.
  • The process for the Oroville BOC is the same as for any other dam project – except this BOC must work at an accelerated pace, in real time with repairs. DWR engineers have and will continue to present information to the BOC, then members of the BOC will comment on DWR preliminary considerations and offer direction prior to DWR making final decisions and furthering design details.
  • Read the BOC memos
  • The forensic team has been engaged to determine the cause of the Oroville spillway incident. To provide for an independent review, DWR contacted the Association of State Dams Safety Officials and the United States Society of Dams to propose a team that can conduct a forensic evaluation. The six members of the forensic team were identified in early March.
  • The forensic team is charged with determining the root cause of the spillway incident, as well as any other contributing causes. These factors may include operational, structural, geologic, and/or management causes, also known as human causes.
  • The team’s preliminary findings were released on May 5 listing 24 physical factors that potentially may have contributed to the main spillway damage and 4 physical factors that may have contributed to the emergency spillway damage. These preliminary findings and forthcoming findings are shared with the BOC as it advises DWR on work to recover spillway function.
  • Read the forensic team’s bios here
  • January and February 2017 were the wettest in 110 years of Feather River hydrologic records.
  • Lake Oroville received an entire year’s average runoff of 4.4 million acre feet of water in about 50 days.
  • More than 5 million acre feet of water was released from Lake Oroville from February through May.
  • 2016-17 is already the wettest year on record for the Northern 8-station index, which includes the Feather River Basin.
  • Snow water content in the Northern Sierra was near 200 percent of normal on April 30, 2017.
  • The Forensics Team is also looking at the role weather may have had on the initial erosion in February.
  • DWR’s construction design will be approved by FERC. The BOC also sent a letter approving DWR’s construction design.
  • DWR continues to work with city and county officials on developing a construction viewing area for the public.
  • DWR is working with the City and County on other ways that the public can view construction. A live feed camera has been installed at the base of the spillway on Oro Dam Road.
  • A viewing room is in process of being completed at the Lake Oroville Visitors Center with additional camera views for the public to see.
  • In February, shortly after the incident, Governor Brown directed the California Natural Resources Agency to conduct more detailed evaluations of dam appurtenant structures, such as spillways, to include geologic assessment and hydrological modeling. The Governor ordered this new review to be expedited for dams that have spillways and structures similar to the Oroville Dam before the next flood season.
  • DSOD identified an estimated 100 dams that have spillways similar to Oroville (size, age, type). Owners of these dams are being asked by DSOD to conduct a site-specific investigation on the integrity of the dam’s spillways. DSOD will review and approve the dam owner’s investigation plan, and once they received the owner’s detailed evaluation, DSOD will conduct an independent review of the dam's appurtenances.
  • Residents who have been economically impacted as a result of the Lake Oroville spillways incident can file an eligible claim with the California Department of General Services.
  • DWR is conducting an aggressive dust management program. Dust management includes regular watering of areas near controlled blasts, as well as wetting the blast areas prior to blasting for additional dust management, and real-time dust monitors surrounding the work site perimeter to verify dust is not migrating beyond the construction site.
  • DWR is working with the Butte County Air Quality Management District to ensure that monitoring of dust plumes caused by heavy equipment and controlled blasting in the construction zone is compliant with local and State air quality regulations.
  • The construction blasting, known as controlled light charge blasting, is safe and a common practice at dam construction sites throughout the country.
  • Controlled light charge blasting methods are used to break up intact rock on the slopes so that it can be safely excavated. Seismographs are located throughout the project area to monitor movements and to make sure recorded vibrations are within safe levels.
  • DWR obtained required permits for the controlled light charge blasting from its state and federal regulatory partners, as well as the Butte County Sheriff’s Department.
  • A settlement agreement between over 50 stakeholders was filed with the Federal Energy Regulatory Commission in 2006. The National Marine Fisheries Service filed its required Biological Opinion with FERC in December of 2016. The new license documents are now awaiting FERC approval. However, there are only 2 Commissioners currently on the 5-member FERC board. To approve the new license there must be a quorum, or 3 Commissioners on the board.
  • It is unclear when the Trump Administration will appoint another commissioner to the FERC board. Until that time the new license is still pending.
  • Significant repairs to the gated (main) spillway were done in 1997 and 2009. In 1997 contract amounts were for $340,000. In 2009, contract amounts were for $776,000.
  • Average annual expenses for maintenance and operation of Oroville has been $20M per year over the last 5 years. An estimated $30 million has been spent over the last 5 years on capital improvements to Oroville Dam.

Community

  • DWR wants to provide regular updates to the community about the progress of the Lake Oroville Spillways Emergency Recovery Project and answer questions and concerns from the community.
  • DWR has recently begun $2.8 million in construction on the Bidwell Saddle Dam Trailhead ($1.2 million) and the Lime Saddle Boat Launch Area in Paradise ($1.6 million). Improvements include widening the gravel parking lots and updating site amenities. Construction will be completed in Spring 2018 and is the first in a serious of projects to help offset the closure of the Spillway Boat Ramp and Diversion Pool Day Use Areas.
  • Funding comes from a DWR-run fund dedicated to recreation at State Water Project facilities. DWR also secured approval for early release for Supplemental Benefit Funds totaling $3 million.
  • DWR implementing additional recreation projects; expediting at same level of priority as Spillway work:
    • Bidwell, Lime Saddle and Loafer Creek Shuttle Service (with DPR).
    • Bidwell Canyon Boat Ramp (Stage 1) Parking Lot Expansion.
    • Bidwell Canyon Marina Parking Lot Expansion.
    • Bidwell and Lake Oroville Marina Access Gangway Walk-In Regrade.
    • Loafer Creek Parking Lot Extension.
    • Lime Saddle Boat Ramp Parking Lot Expansion. (in progress)
    • Bidwell Canyon (Stage 1) Boat Ramp Expansion.
    • Enterprise Boat Ramp Expansion.
    • Saddle Dam Trailhead Parking Improvements.
  • DWR seek approval of additional recreation enhancements:
    • Bidwell Canyon Boat Ramp (Stage 2) Parking Lot Expansion and Ramp Addition.
    • Loafer Creek Boat Ramp Stage 2 Ramp Expansion (DWR is determining if this needs FERC approval or can proceed).
  • The DWR Department of Flood Management is completing the Feather River Conveyance Re-Evaluation on the Feather River south of Marysville to the Sutter Bypass and in some parts of Feather River north to the Thermalito Afterbay.
  • DWR, USACE and the Sutter Butte Flood Control Agency are beginning a $28.5 million repair to three miles of levees in Yuba City.
  • The Department of California Fish and Wildlife and DWR have installing 5,000 cubic yards of spawning gravel near the Feather River Fish Hatchery.
  • CDFW established production goals of 450,000 steelhead, 2 million spring run salmon, 6 million fall run salmon for mitigation, and 1-2 million fall run salmon for enhancement.
  • DWR modified ramping rates where feasible in response to input.
  • DWR began providing advance notification of gated flood control spillway operations and significant flow changes, in coordination with LMAs and County OES
  • DWR has worked with individual growers to identify potential federal and state assistance for crop losses.
  • Since 2007-2008 DWR has invested approximately $366 million for repairs and improvements in the Feather River basin to reduce flood risk and conduct system repairs.
  • During the February-March high water events, DWR provided over $4 million for direct assistance at six Feather River sites.
  • DWR is committed to regular public meetings and briefings.
  • DWR attends Board of Supervisors and Oroville City Council meetings.
  • DWR meets with federal, state, local officials to respond to their questions & concerns and provide information.
  • DWR and local, state, federal partner agencies meet in weekly Cooperators Meeting.
  • DWR participates regularly in Oroville Recreation Advisory Committee (ORAC).
  • DWR made rapid, minute-by-minute decisions to assure public safety and to restore the spillways, and consulted with all appropriate state and local emergency services and law enforcement officials throughout the process.
  • We plan to sustain regular communications going forward, as we transition to recovery, with the public meetings as a start, and with more collaboration opportunities going forward.
  • Department of Parks & Recreation
  • Department of Fish & Wildlife
  • CAL FIRE
  • California Conservation Corps
  • California Highway Patrol
  • California National Guard
  • Office of Emergency Services
  • CalTrans
  • Butte County Sheriff, OES, Public Works
  • City of Oroville, Police Dept., Fire Dept.
  • Gridley-Biggs Police Department
  • Oroville Hospital
  • Bureau of Indian Affairs
  • PG&E
  • Red Cross
  • Association of Dam Safety Officials
  • U.S. Society on Dams