Lake Oroville is a reservoir formed by the Oroville Dam impounding the Feather River, located in Butte County, northern California. The lake is situated northeast of the city of Oroville, within the Lake Oroville State Recreation Area, in the western foothills of the Sierra Nevada. Known as the second-largest reservoir in California, Lake Oroville is treated as a keystone facility within the California State Water Project by storing water, providing flood control, recreation, freshwater releases to assist in controlling the salinity intrusion into the Sacramento-San Joaquin Delta and protecting fish and wildlife.
The lake is a popular nationally renowned bass fishing location, while coho salmon are stocked from the Feather River Fish Hatchery. This hatchery is a main component of Lake Oroville.
History
The local indigenous tribe were the Konkow Maidu (translation is 'man') who originally settled the lake region and Feather River for many years. Today many of the small towns including Oroville were originally occupied by the Maidu people. In 2002, a Sonoma State study took archaeological inventory of the of Lake Oroville to learn 250 sites are from the prehistoric era relating to the Native American life along the Feather River and an additional 478 sites dating to the Gold Rush. These sites included open-air residential sites, caves and rockshelters, limited lithic scatters, rock art, quarries and workshops, bedrock milling sites and cemetery areas. Natives' lives were disrupted by gold discovery in 1848 and the miners infiltrated their lands. In April 1848, only three months after gold was discovered at Sutter's Mill, John Bidwell found gold on the Feather River at a spot known today as the town of Bidwell Bar. Bidwell began to work the claim using local Konkow Maidu workers. Due to the rapidly spreading news of the California strikes, in under a year California's non-native population climbed from 20,000 to 100,000. By 1850, Butte County alone supported 3,052 miners.
Construction on the dam began in 1957 to relocate what is now Highway 70 and the then Western Pacific (now Union Pacific) Railroad. A few years later the partially completed dam checked flooding on the Feather River in December 1964. This saved the Sacramento Valley from flooding.
Prior to impoundment by the Oroville Dam, the current main basin of Lake Oroville was the location of the confluence of the North Fork Feather River with the Feather River () and the now-inundated towns of Bidwell () and Land (). Completed in 1968, Oroville Dam is an earthen dam and is the tallest dam located in the United States, measuring over high and across. The dam was the largest earth-fill dam in the world until succeeded by Aswan High Dam in Egypt. It was built by the California Department of Water Resources as part of the California State Water Project. The dam houses the Edward Hyatt Powerplant, an underground hydro-electric plant that was completed in 1967. Six generators are used to provide a maximum generating capacity of 819 MW.
Hydrology
Lake Oroville and Oroville Dam are part of the Oroville–Thermalito Complex, a water infrastructure complex including the Hyatt Powerplant, Thermalito Diversion Dam and Powerplant, the Feather River Fish Hatchery, Thermalito Power Canal, Thermalito Forebay, Thermalito Pumping-Generating Plant, Thermalito Afterbay, and the Lake Oroville Visitors Center.
The lake is fed by the North Fork, Middle Fork, West Branch and South Fork of the Feather River watershed. This watershed drains an area of . The North Fork and Middle Fork Feather Rivers comprise of this area which includes portions of the foothill and mountain regions of the northern Sierra Nevada and southern Cascade Range. Storing over , it is the second-largest reservoir in California, after Shasta Lake. About one-third of the water released from the reservoir goes to uses between the Oroville and Sacramento–San Joaquin Delta.
Lake Oroville plays an important role in flood management, water quality, and the health of fisheries affecting areas downstream like the Sacramento-San Joaquin River Delta. During the warm season, the primary source of streamflow is melting snow, occurring April 1 – July 31, and Lake Oroville receives about 40 percent of the annual total inflow. The lake's storage and releases are a key part of the hydropower and water-supply facilities of the Oroville Complex, the reason it's a pillar and major source of flexibility of the SWP. The downstream flow limits set by the USACE for Lake Oroville are north of Honcut Creek, above the mouth of the Yuba River, and south of the Bear River.