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Frequently Asked Questions

Incident, Response and Recovery

  • The objective of the recovery effort is to ensure that by November 1, 2017, the flood control spillway, also known as the main spillway, can accommodate inflows from the Feather River watershed to Lake Oroville and subsequent releases from the Lake.
  • By November 1, DWR will remove and reconstruct 2,270 feet of the main spillway. DWR will patch and add additional anchoring to the uppermost portion of the main spillway – 730 feet from where the gates are – this year and remove and reconstruct it during the 2018 construction season.
  • By December of 2017 or January 2018, DWR will complete construction of an underground cut-off wall downstream of the emergency spillway which will prevent uphill erosion in the event the emergency spillway is ever used again.
  • The new construction design will meet and exceed today’s modern standards, which includes factors such as the type of concrete used, thickness of the concrete, new drains installed, and enhanced monitoring methodology.
  • Final plans, project designs and cost estimates are still being developed.
  • The $275 million awarded to Kiewit was based on a 30-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 The Governor’s Office of Emergency Services (Cal OES) to secure the maximum reimbursement allowable under FEMA's disaster assistance program for all eligible disaster related costs.
  • The Federal Emergency Management Agency (FEMA) can cover up to 75 percent of the eligible emergency response and Oroville Dam complex repair costs.
  • The Department of Water Resources (DWR), the Federal Energy Regulatory Commission (FERC), the Division of Safety of Dams (DSOD), the Governor’s Office of Emergency Services (Cal OES) and the Butte County Sheriff deemed it necessary for the safety of residents downstream.
  • The primary focus of any emergency response is the safety of residents.
  • 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 main spillway has only been used four times prior to January 1. The rate of release from the main spillway has only exceeded 100,000 cfs in 5 of the 49 years.
  • Since 1969, the spillway gates have only been opened four times before January 1 – 1982, 1984, 1997, and 2006.
  • DWR’s prime contractor, Kiewit Infrastructure West, expects to employ 600 people at the peak of construction. Most of the workers are local to the immediate region, as well as neighboring northern California cities.
  • The Lake Oroville Spillways Emergency Recovery 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
  • FEMA has reimbursed $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 and DWR values the partnership with FEMA and Cal OES and look forward to working together.
  • The disaster declaration signed by President Trump on April 1, 2017 made FEMA’s Public Assistance program available to public entities and certain nonprofits. 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.
  • A Board of Consultants (BOC) is required by California Water Code (Division 3, Part 1, Chapter 3, Section 6056) to evaluate and review 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 Lake Oroville Spillways Emergency Recovery Plan is being reviewed by the BOC.
  • 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 regularly 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.
  • The Independent Forensic Team (IFT) has been engaged to determine the cause of the Lake Oroville spillway incident. To ensure an independent review process, DWR contacted the Association of State Dam Safety Officials (ASDSO) and the United States Society of Dams for recommendations of team members. The six members of the IFT were identified in early March 2017.
  • The IFT will determine the 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
  • These preliminary findings and forthcoming findings are shared with the BOC as it advises DWR on work to recover spillway function.

Safety and Security

  • The Lake Oroville spillways and Oroville Dam are separate structures. The structural integrity of Oroville Dam was never at risk and remains sound.
  • The vegetation area is a seasonal wet band of vegetation on the face of Oroville Dam. It is not a threat to the integrity of Oroville dam.
  • It was observed during construction in 1966 and 1967 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
  • A DSOD inspection from February 1, 1967 on the face of Oroville Dam observed ponded and perched water and seepage bands from rain water in the fill area. The conclusion by the DSOD inspector was that this should not be a problem except for public relations and maintenance.
  • 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. Sensitive seepage monitoring equipment and a vertical drain near the core of the dam would intercept and alert DWR to any abnormal seepage. These levels have remained constant since construction of Oroville Dam in the late 1960’s.
  • Yes, the independent Board of Consultants assigned to the Lake Oroville spillways project received a briefing on the findings and conclusions in this assessment and concurred with DWR.
  • Yes, a full comprehensive evaluation of Oroville Dam is underway and will include an in-depth evaluation of the vegetation area. The evaluation is expected to be complete by 2019.
  • Dating back to the construction of Oroville this area has been called the “Green spot.” But as this assessment is technical in nature, so is the description of the area, which is a patch of overgrown vegetation that is caused by rain water on the face of the Oroville Dam.
  • Any assessment, inspections or evaluation of the appurtenant structures of the Oroville Dam are conducted through the federal and state oversight agencies assigned to provide those functions.
  • The Lake Oroville 2017/2018 Flood Control Season Operations Plan will guide DWR reservoir operations at Lake Oroville from winter to April 2018. To ensure public safety while construction continues, the plan calls for DWR to maintain lower-than-average lake levels during the winter months to provide space for inflows and manage releases from the substantially reconstructed main spillway.
  • The plan calls for DWR to lower the lake level to an elevation of 700 feet by November 1, compared to the average 780 feet elevation maintained on that date in prior years. The lower level will provide more than 2.2 million acre-feet of flood reserve storage to accommodate inflows during the rainy season. In the event the reservoir rises quickly during the winter months, the operations plan identifies certain elevations at which DWR will increase outflows through the Hyatt Powerplant, the river valve outlet or the main spillway to safely manage lake levels.
  • In addition to developing an interim operations plan with the U.S. Army Corps, DWR will initiate a public process to update Lake Oroville’s long-term operations plan.
  • Following rules and guidelines set by the Federal Energy Regulatory Commission (FERC), DWR evaluates all public documents related to the Lake Oroville Spillways 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.
  • FERC Part 12D reports are a long-standing part of the monitoring and inspection process of hydroelectric facilities and dams under the jurisdiction of FERC.
  • Part 12D is a section of the report that 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 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.
  • 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.
  • 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.
  • 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 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 (DSOD) and the Federal Energy Regulatory Commission (FERC).
  • California’s inundation map program for dam failure is a responsibility of the Governor’s Office of Emergency Services (Cal OES) and is handled specifically under the Hazard Mitigation Program.
  • The Cal OES Dam Inundation Mapping and 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 here. Please note that this map does NOT represent a spillway failure, only a total Oroville dam failure.
  • We welcome additional analyses and studies and have confirmed that this report has been shared with the Forensic Team.
  • 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.
  • Memos from the Board of Consultants and the Forensic Team are posted on our website.
  • Consistent with DWR policy and FERC guidelines, some of the memos were redacted to remove 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.

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 in 2016.
  • DSOD has released extensive information about how dams in California are classified and monitored. Fact sheet.
  • 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.
  • The cause of the main spillway failure is being investigated by the Forensic Team, an independent team of internationally respected scientists and engineers. Their findings will be made public in a final report in the fall.
  • Twice a year, Oroville Dam is inspected by DSOD. The last inspection by DSOD was conducted in August 2016. Oroville Dam is then 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. These inspections of Oroville Dam and its spillways have concluded they are safe to operate.
  • 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 assessments and hydrological modeling.
  • The Governor ordered this new review to be expedited for dams that have spillways and structures similar to Oroville Dam before the next flood season.
  • DSOD identified 93 dams that have spillways similar to Oroville Dam (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.
  • January and February 2017 were the wettest months on record in the 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 the wettest year on record for Northern California. The Feather River Basin is one of the spots measured in the Northern Sierra 8-Station Index, a collection of eight key sites across the Feather, American, and Sacramento River watersheds measured daily to determine rainfall averages.
  • Snow water content in the Northern Sierra was near 200 percent of normal on April 30, 2017.
  • The Federal Energy Regulatory Commission (FERC) and the California Division of Safety of Dams (DSOD) approved the Lake Oroville spillways construction plan for 2017. The independent Board of Consultants (BOC) also approved the construction plans for 2017 and provides continuous project oversight.
  • Since 1968, advancements in the production of concrete and spillway designs in general have come a long way. The minimum thickness of the main spillway slabs will be three and a half feet, and in many cases eight feet thick. The minimum thickness of the 1968 main spillway was 15 inches and a maximum of three feet.
  • The 1968 main spillway drains were made of clay and the 2017 design will use advanced PVC.
  • The side walls in 1968 were only one feet thick, but all side walls will be two feet thick in the 2017 design.
  • DWR and Kiewit will share as much of the construction progress as possible. Regular news releases from DWR and Kiewit about construction progress can be found here.
  • Aerial footage of the construction process can be watched at DWR’s YouTube channel.
  • Construction photographs can be found on DWR’s Facebook page.
  • A live feed of construction work on the main spillway can be viewed through the California State Parks.
  • 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.
  • The license allows DWR to operate the hydroelectric power facilities and provides funding for recreation improvements around the lake. The original license expired in 2007 and has been extended each year.
  • An alternative license agreement among more than 50 stakeholders was filed with the Federal Energy Regulatory Commission in 2006.
  • Also, the National Marine Fisheries Service filed its required Biological Opinion with FERC in December of 2016. The Opinion found no negative effects to fish populations from the re-licensing approval.
  • Approval for the license was on hold due to the FERC board not having a quorum. The board needs at least three commissioners to vote on decisions and licenses.
  • As of August 2017, three nominees were confirmed by the United States Congress and FERC now has a voting quorum.
  • Significant repairs to the 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 Dam has been $20 million per year over the last five years. An estimated $30 million has been spent over the last five years on capital improvements to Oroville Dam.
  • To meet our goal of a fully reconstructed spillway within two years, DWR planned to demolish this additional 270-foot portion of the spillway for a total of 2,270 feet removed and replaced this year.
  • The controlled blasts in this area were planned however, they occurred ahead of receiving formal approval from our oversight groups. DWR halted blasting while the Department and its contractors investigated these incidents and created an action plan to ensure this does not happen again. On July 7, the dam safety regulatory agencies approved these new protocols and demolition resumed.
  • Yes, RCC is preferred because it dries quicker and is still as strong as structural concrete, however it does not contain reinforcing steel.
  • The design criteria for the new repairs this year (2017/2018 flood season) is 270,000 cfs for the main spillway and 30,000 cfs emergency spillway. This brings the total capacity for 2017/18 season to 300,000.
  • Moving forward, per FERC and DSOD’s requirement, we will build the structures to pass approximately 700,000 CFS — a "biblical year” of weather. We currently are in the design phase of what that will look like.
  • The highest amount the main spillway has ever passed is 150,000 cfs during the 1997 winter storms. During the February 2017 spillways incident, flows only reached 100,000 CFS.
  • There is a difference between design criteria and operations. If the region were to deal with extreme flood conditions, the spillway needs to have the ability to release 270,000 CFS to ensure the Oroville Dam. DWR will not release water flows that jeopardize the integrity of downstream levees.
  • The US Army Corps of Engineers and DWR plan to update the Oroville Dam Flood Control Manual after completion of the Lake Oroville Spillways Emergency Recovery Project. The update will be a multi-year process and will include public engagement.
  • DWR developed the Lake Oroville 2017/2018 Winter Operations Plan to manage the reservoir during construction. Click here to learn more about the plan.

Community

  • DWR is committed to regular public meetings and briefings. You can find a complete list of scheduled meetings and briefings here. DWR is also starting a monthly elected call to share updates and answer questions related to the spillways.
  • DWR attends Board of Supervisors and Oroville City Council meetings, and other county and city meetings in downstream communities.
  • DWR meets with federal, state, and local officials to respond to their questions and concerns and provide information.
  • DWR and local, state, federal partner agencies meet in weekly Cooperators meetings.
  • DWR participates regularly in Oroville Recreation Advisory Committee (ORAC).
  • DWR is negotiating an agreement with Butte County and City of Oroville to pay for repairs to non-haul roads. Currently, the Traffic Control Plan limits trucks to 150 per day.
  • In consultation with the City of Oroville and Butte County, DWR will update traffic plans in response to new information. DWR has met with residents concerned about construction noise and light. Kiewit is conducting noisier activities during daylight hours.
  • DWR started a $2.8 million construction project on the Bidwell Saddle Dam Trailhead ($1.2 million) and the Lime Saddle Boat Launch Area in Paradise ($1.6 million) in the summer of 2017.
  • Improvements include widening the gravel parking lots and updating site amenities. Construction will be completed in Spring 2018. DWR is currently in the design phase of the approved expansion to the Loafer Creek Recreation Area. Construction will lower the boat ramp and add additional lanes and parking.
  • DWR’s 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 engaged in a $28.5 million repair to three miles of levees in Yuba City.
  • The Department of California Fish and Wildlife and DWR have installed 5,000 cubic yards of spawning gravel near the Feather River Fish Hatchery.
  • CDFW established production goals of 450,000 steelhead, two million spring run salmon, six million fall run salmon for mitigation, and one to two million fall run salmon for enhancement.
  • DWR modified ramping rates in April and May 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.
  • Flow changes can be found here.
  • 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
  • The deadline to file a claim was Friday, August 11, 2017, six months after an emergency was declared. For more information, click here.
  • Call (800) 955-0045 or email gcinfo@dgs.ca.gov if you have any questions.
  • The Spillway Boat Ramp and Day Use Area will remain closed throughout the duration of construction. Once the Lake Oroville Spillways Emergency Recovery Project is completed in 2018, DWR will assess all public access points at Lake Oroville, including the Spillway Boat Ramp.
  • 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