Lake Oroville on January 19, 2018 with lake levels at 707 feet
Today, the Independent Forensic Team (IFT) released additional findings from its review of the February 2017 Lake Oroville Spillways incident. The report builds on the IFT’s interim memo from September 2017 that identified physical causes of the incident. While DWR is in the process of fully reviewing this lengthy report, the Department intends to incorporate the latest findings into its ongoing efforts.
“We strongly supported having an independent assessment of the spillway failure and take the findings very seriously,” said DWR Director Grant Davis. “This report is consistent with the independent team’s initial technical findings from last May which were fully incorporated in the design of the reconstructed spillways. As we have done in the past, we will carefully assess this report, share it with the entire dam safety community and incorporate the lessons learned going forward to ensure California continues to lead the nation on dam safety.”
The Department has already made significant progress to bolster the dam safety program to include comprehensive re-evaluations of every spillway with attributes similar to Lake Oroville’s. These re-evaluations go far beyond the standard inspections to include extensive hydrologic, structural and geotechnical work and a thorough investigation of records.
In May, DWR began planning for a comprehensive needs assessment of the entire Oroville complex to understand what changes, if any, need to be made long term to bolster dam safety of the Oroville complex.
An evaluation of DWR’s dam safety program is already underway, and as a result of the IFT’s findings, DWR will also assess its existing organizational structures. DWR will continue to invest in resources to learn from other dam safety programs and plans to convene experts over the coming months to digest the findings and recommendations from this report to identify tangible actions in response.
In addition to identifying the combined causes that led to the incident, the latest IFT report also comments on decisions made as the spillway incident unfolded in February 2017.
“During the incident, our sole focus was protecting public safety,” said Joel Ledesma, Deputy Director of the State Water Project. “DWR supported this independent assessment – so we can learn from the past and continue to improve now and into the future.”
DWR agrees with the IFT’s conclusion that all dam owners need to reassess current procedures. As the report notes, “the fact that this incident happened to the owner of the tallest dam in the United States, under regulation of a federal agency, with repeated evaluation by reputable outside consultants, in a state with the leading dam safety regulatory program, is a wake-up call for everyone involved in dam safety. Challenging current assumptions on what constitutes ‘best practice’ in our industry is overdue.”
Background
Following the February incident, the Federal Energy Regulatory Commission directed DWR to establish an Independent Forensic Team to determine the root cause of the spillway incident, as well as other contributing causes including operations, structural, geologic, and management. To provide an independent review, DWR contacted the Association of State Dam Safety Officials and the United States Society of Dams, two nationally recognized dam safety organizations, to propose a team of experts capable of conducting a forensic evaluation of the Lake Oroville spillways incident. The six members of the IFT were identified on March 15.
Preliminary findings were released on May 5, 2017, listing 24 physical factors that potentially contributed to the main spillway damage and four physical factors that may have contributed to the emergency spillway damage.
On September 5, 2017, the IFT published an interim memorandum summarizing its findings of the Lake Oroville spillways failure and DWR released a statement regarding the memo. The latest report from the IFT incorporates these previous findings in addition to the contributing human factors.
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