Page - 147 - in Book of Full Papers - Symposium Hydro Engineering

a report of findings. At the request of DWR, the United States Society on Dams (USSD) and the Association of State Dam Safety Officials (ASDSO) coordinated the assembly of a six-person team, which was approved by FERC. The IFT, composed of the authors of this paper, issued its forensic investigation report on January 5, 2018 [1]. The IFT’s work included the review of hundreds of documents covering investigations, design, construction, operations and project reviews, as well as notes taken during the incident. IFT members visited the site, including during forensic investigations made before chute sections were demolished for repairs. The IFT also interviewed more than 75 individuals, conducted two surveys of DWR personnel, and solicited input from the public and DWR employees. Through an iterative process, the IFT applied a mix of fundamental inductive and deductive logic to the assembled information, and provided the resultant evidence, arguments, and findings in its detailed forensic report [1]. The report addressed both the physical factors and the human, organizational, and industry factors that contributed to the Oroville Dam spillway incident. This paper briefly summarizes the IFT’s findings and lessons to be learned from this very serious incident. The reader is referred to the full forensic investigation report [1] for more detailed information. 2. PROJECT BACKGROUND 2.1. OROVILLE DAM PROJECT Oroville Dam is a component of the California State Water Project (SWP), which is the largest state-owned water storage and delivery system in the United States. The Oroville Dam and associated structures were built in the 1960s, with the construction completed in 1968. The SWP is owned and operated by DWR, which is part of the California Natural Resources Agency and was created in 1956. Oroville Dam is regulated by a separate division within DWR, the Division of Safety of Dams (DSOD), as well as by FERC. The Oroville Dam facility (see Fig. 1) consists of an embankment dam, a service spillway (also known as the Flood Control Outlet or FCO Spillway), an emergency spillway, the Hyatt Powerplant, and several other appurtenant structures. Oroville Dam is the tallest dam in the United States, at 235 m (770 ft). The design embankment crest is at Elevation 281.0 m (922 ft), and the maximum normal operating pool level is Elevation 274.3 m (900 ft). For reference, the service 147