In March of 2017, Underwater Acoustics International was called to assist with the response to the Oroville Dam primary and secondary spillway failure incident. The UAI team along with underwater contractor, DRS Marine, performed an investigation of the upstream face of the gated spillway structure and the adjoining reservoir approach to look for any damage or erosion at the concrete structure and reservoir junction and adjoining reservoir approach. Investigations of each gate bay were also performed looking for excessive debris or apparent damage. A multi-axis, articulating steered beam sonar was used to provide high resolution acoustic imaging of the structure and water bottom components. A similar investigation of the Thermalitos diversion structure, downstream of the primary spillway was also conducted in conjunction with the investigation at the primary spillway. Our team at Underwater Acoustics International gathered beneficial information as to the current conditions at the underwater components of the structures at Oroville Dam in support of the recovery effort.
On January 5, 2018, an independent team published a forensic report regarding the Oroville Dam incident. Here is a summary of their findings. “The Oroville Dam spillway incident was caused by a long-term systemic failure of the California Department of Water Resources (DWR), regulatory, and general industry practices to recognize and address inherent spillway design and construction weaknesses, poor bedrock quality, and deteriorated service spillway chute conditions. The incident cannot reasonably be “blamed” mainly on any one individual, group, or organization.”