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Oroville Dam

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The Oroville Dam is a massive earthfill embankment dam located on the Feather River in California.

Oroville
Oroville

Situated in the Sierra Nevada foothills, it stands 770 feet tall. This height makes it the tallest dam in the United States. The dam serves three primary functions: water supply, hydroelectricity generation, and flood control. It creates Lake Oroville, which is the second-largest reservoir in California. The dam is a central part of the California State Water Project (SWP). This project helps manage water across the entire state.

To manage water, the dam controls the flow of the Feather River. Water is stored in Lake Oroville and then sent through the California Aqueduct. This system provides water for irrigation in the San Joaquin Valley. It also supplies municipal and industrial water to coastal Southern California. To generate power, the dam uses the Edward Hyatt Power Plant. This facility was once the largest underground power station in the country.

Edward Hyatt Powerplant during its shutdown in August 2021-5993
Edward Hyatt Powerplant during its shutdown in August 2021-5993

The dam also uses spillways to release extra water during heavy rains.

Construction of the dam began in 1961 under engineer Donald Thayer.

Oroville dam
Oroville dam

Workers used two large concrete-lined diversion tunnels to move the river around the site. One tunnel handled normal flows, while the second was for floods. To build the embankment, a specialized rail line moved earth and rock. About 120 train cars ran on this line every hour. Much of the material came from old hydraulic mining debris from the Gold Rush. The dam was topped out in 1967 and officially dedicated in May 1968.

Building the dam was a dangerous and difficult process. In 1964, a massive Christmas flood nearly overtopped the incomplete structure. However, the dam reduced the peak water flow by nearly 40 percent. This helped prevent massive damage to the surrounding area. Construction also saw tragic accidents, including a head-on train collision in 1965. In total, 34 men died during the construction period. The dam was designed to withstand strong earthquakes. It contains hundreds of instruments to measure water pressure and earth movement. Because it sends data back to engineers, it is nicknamed "the dam that talks back."

The dam has also had significant environmental and safety challenges. It blocks fish migration up the Feather River, which affects the local habitat. To help, a salmon and steelhead fish hatchery was built nearby. In 2009, a dangerous accident occurred in a river valve chamber. Suction from a flowing valve created a vacuum that injured a worker. More recently, the dam faced a major crisis in 2017.

Oroville Dam spillway damage 27 Feb 2017
Oroville Dam spillway damage 27 Feb 2017

During the wettest winter in over 100 years, the main spillway began to fail. Erosion damaged the concrete and the foundation under the spillway.

This 2017 spillway failure was a serious event for the region. The damage was so large that engineers had to use the emergency spillway.

Oroville dam
Oroville dam

This caused the evacuation of 188,000 people living near the dam. High water levels and debris also affected the Feather River Fish Hatchery. Engineers worked to stabilize the site and lower the reservoir levels. The main spillway was eventually reconstructed by November 1, 2018. In April 2019, officials successfully tested the repairs with large water releases.

Oroville Dam main spillway rebuild phase 2
Oroville Dam main spillway rebuild phase 2

The history of the Oroville Dam shows how California's needs changed over time. In 1935, the federal government focused on the Central Valley Project for agriculture. After World War II, California experienced an economic boom. The state needed water for growing cities and industries, not just farms. This led to the proposal of the Feather River Project by A. D. Edmonston in 1951. Although there was political opposition, major flooding in the 1950s helped secure funding. Today, the dam remains a vital part of the state's massive water infrastructure.

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File:Oroville Dam spillway damage 27 Feb 2017.jpg
Oroville Dam spillway damage 27 Feb 2017.jpg
File:Oroville Dam main spillway rebuild phase 2.jpg
Oroville Dam main spillway rebuild phase 2.jpg
File:Edward Hyatt Powerplant during its shutdown in August 2021-5993.jpg
Edward Hyatt Powerplant during its...
File:Oroville.jpg
Oroville.jpg
File:Oroville_dam.jpg
Oroville_dam.jpg
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