. South Fork The South Fork Feather River originates in southern Plumas County near the Plumas-Sierra county line, at . It heads on the southwest slope of Pilot Peak, just north of Gibsonville Ridge and Bunker Hill Ridge. It flows west and southwest to Little Grass Valley Reservoir, an impoundment created by Little Grass Valley Dam. Below the dam the South Fork flows southwest between Mooreville Ridge and Lumpkin Ridge and enters Butte County. Just before entering Lake Oroville the Ponderosa Diversion Dam impounds the South Fork in the Ponderosa Reservoir. Below the dam the river becomes the south arm of Lake Oroville. The mouth of the South Fork is considered to be where the river empties into Ponderosa Reservoir, . The mouth was formerly located farther west at , until it was inundated by Lake Oroville. The total stream distance from the head of the South Fork to the juncture with the Middle Fork in Lake Oroville is . West Branch The West Branch Feather River, sometimes called the West Fork Feather River, has a drainage area that is small but slightly larger than that of the South Fork. It originates in Butte County at , in Lassen National Forest. It flows southwest through Snag Lake and by Coon Hollow, after which it is joined by Philbrook Creek, which drains Philbook Reservoir to the east. From there the West Branch flows more directly south and leaves Lassen National Forest. It is joined by Fish Creek and Last Chance Creek (there are several streams named Last Chance Creek in the Feather River watershed). Downstream from Last Chance Creek a diversion dam draws off some of the West Branch's water. The diverted water flows into Hendricks Canal, a long conduit composed of ditch, flume, and tunnel sections, with a capacity of . Along with other facilities, such as Philbrook Reservoir, Hendricks Canal is part of the Toadtown development, which conveys water through the several canals and powerhouses. The water ultimately empties into Butte Creek, a tributary of the Sacramento River. Another diversion dam on the West Branch Feather River near Magalia, called the Magalia 73 Dam, conveys water into the Upper Miocene Canal, which runs to Kunkle Reservoir and the Lime Saddle Powerhouse on Lake Oroville. From the powerhouse water is carried by the Middle Miocene Canal to the Coal Canyon Powerhouse and on into the Oroville-Thermalito Complex. The Miocene Canal