DWR Releases Initial Findings from Forensics Team Regarding Lake Oroville Spillways

SACRAMENTO May 10, 2017 – The California Department of Water Resources (DWR) today made public a memo from the independent Forensics Team, which outlines a list of potential physical factors that may have contributed to the Lake Oroville gated (main) spillway failure on Feb. 7.

“This memo outlines the potential causes of the main spillway failure, which will be thoroughly investigated by the Forensics Team over the next few months,” said DWR Acting Director Bill Croyle.  “Although this is preliminary information, we are taking it into consideration as we develop plans to reconstruct the spillway.”

In a conference call briefing on Thursday, May 4, the team presented a preliminary list of candidate physical factors that could have potentially contributed to the initial failure mechanisms at the main spillway to DWR, the independent Board of Consultants (BOC), the Federal Energy Regulatory Commission (FERC), and the California Division of Safety of Dams (DSOD).

The purpose of this list is to outline the potential causes of the spillway damages, to ensure that DWR considers these factors in the new design.

DWR has posted the Forensics Team memo online.  DWR expects to receive the Team’s final report in fall of 2017 which will outline what caused the failure.

Consistent with DWR protocol, every memo from the Forensics Team will be posted in the same format it was received, with Critical Energy Infrastructure Information (CEII) redacted as needed CEII is considered a security risk, as it contains design details about the Oroville Dam facilities.

Background on the Forensics Team

The Forensics Team is assigned to prepare an independent report on the actual contributing factors that led to the failure of the main spillway at Lake Oroville.  As outlined in the letter dated February 13, 2017, FERC requested that DWR complete a forensic analysis aimed at determining the cause of the main spillway failure and determining if the failure mode could occur again.  The Association of State Dams Safety Officials and the United States Society of Dams, assembled the independent team of experts in April that could conduct a forensic evaluation.  Furthermore, FERC requested that the BOC and the DSOD be allowed to review and comment on the ongoing investigation, including possibly requesting additional information or analysis be completed by the forensic team regarding the analysis.