Water & Drought

5 things to know about the Oroville Dam

Oroville Dam progress: Watch crews pour concrete into spillway section

Oroville Dam’s main flood control spillway cracked in two Feb. 7, leaving an enormous chasm that hindered water releases and eventually triggered the evacuation of 188,000 downstream residents. On Wednesday, July 7, 2017, state officials said they
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Oroville Dam’s main flood control spillway cracked in two Feb. 7, leaving an enormous chasm that hindered water releases and eventually triggered the evacuation of 188,000 downstream residents. On Wednesday, July 7, 2017, state officials said they

The Oroville Dam has been making headlines for decades, but especially since a damaged spillway in February forced the evacuation of nearly 200,000 people. Here are some things you may not know about the dam:

1. It’s the tallest dam in the U.S. At 770 feet high, the Oroville Dam tops Hoover Dam and downtown Sacramento office towers. It fares less well against the world’s tallest dams – the Jinping-I Dam in China towers over it at 1,001 feet.

The dam boasts some other big numbers. The earthfill dam, completed in 1967, spans 6,920 feet in length and 50 feet in width at the crest. It contains 80 million cubic yards of dirt and rock. Behind the dam, Lake Oroville has a maximum operating storage capacity of 3.5 million acre-feet of water. (Each acre-foot covers an acre of land one foot deep, about as much water as a typical suburban family uses in one year.) At its fullest, the lake covers 15,810 acres and has a 167-mile shoreline – the driving distance from Sacramento to Yosemite National Park.

2. It was completed in 1968. Construction began in 1961. Former governor Pat Brown, father of current Gov. Jerry Brown, pushed hard for the Oroville Dam as part of the State Water Project.

Determined to leave a personal legacy, Brown misled voters about the State Water Project’s costs, ignored recommendations to delay Oroville’s construction and brushed aside allegations that substandard building materials were being used at the dam, archives, oral histories and other documents show. His administration steamrolled past a land-speculation scandal, relentless labor strife and the deaths of 34 workers to get Oroville built on time.

3. Spillway repairs will cost $275 million. The dam’s main flood control spillway ruptured Feb. 7, leaving an enormous chasm that hindered water releases and eventually triggered the evacuation of 188,000 downstream residents. Reconstruction of the spillway will last through 2018.

Kiewit Corp. of Omaha, Neb., which was awarded a $275.4 million contract to fix the dam’s two spillways, says it will have up to 500 workers on-site by August and plans to work 20 hours a day, six days a week, to get as much work as possible done this summer.

4. The dam produces 2.2 billion kilowatt hours of energy per year. The Edward Hyatt Powerplant, located underground on the Feather River downstream from the Oroville Dam, takes its name from Edward Hyatt, state engineer of the former division of water resources, now the Department of Water Resources. When it was constructed, it was the largest underground power station in the United States. The 2.2 billion kilowatts of energy produced per year by the Hyatt Powerplant in conjunction with the nearby Thermalito Powerplant provides about half the total power produced by the State Water Project’s eight hydroelectric facilities.

5. It’s one of California’s seven wonders of engineering. The California Society of Professional Engineers bestowed the honor on the dam in 1967.

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