Oroville Dam is on the Feather River above the city of Oroville in Butte County, California. It creates Lake Oroville, generates electricity, and provides drinking and irrigation water for Central and Southern California. The dam, lake and other facilities are owned & operated by the State of California Department of Water Resources and are part of the California State Water Project.
Oroville Dam is the tallest dam in the United States and is in the top twenty in the world for dam height and volume of dam materials. It is an earth-fill dam, stands 770 feet tall, is 6,920 feet (2,317 m) long, and holds 3,537,577 acre-feet (4.364 km³) of water. Construction started in 1961 and was completed in 1968, at a cost of $187.8 million; however, as a result of the multi-purpose nature of the dam (designed to provide water supply, flood control, power generation, and fish and wildlife enhancement), the total costs were $563.8 million.
Over the past 12 years the dam has saved an estimated $1.2 billion in flood damage to the surrounding area. During a particularly devastating flood in 1997 Oroville managed to reduce the total peak flow from the storm from 300,000 to 150,000 cfs (on the dam) and flooding on the land below the dam was reduced from 530,000 to 315,000 cfs. This resulted in an estimated total savings from that one storm of $1 billion.
The Oroville Projects powerplant (Edward Hyatt Powerplant) works in tandem with another nearby power facility, Thermalito Pumping-Generating Plant; together they have a licensed hydro-power capacity of 760 MW and actually produce around 2.2 billion KWH of energy annually.
It was not known until 1975, when a magnitude 6.1 earthquake occurred near Oroville, that the dam sits on top of an active faultline. This caused serious questions to be asked regarding the Auburn Dam which was just beginning construction at the time and was never built as a result of the possible geologic risk.