American River
The North Fork is the longest tributary of the American River, at . It begins at an elevation of about near Lake Tahoe in Placer County at Mountain Meadow Lake, just northeast of Granite Chief and immediately due west of Squaw Valley Ski Resort. It flows westward through remote wilderness areas.
American River
Eight hydroelectric plants on the South Fork are operated by Sacramento Municipal Utility District (SMUD) as the Upper American River Project. These plants are fed by a series of reservoirs including Loon Lake, Ice House Reservoir and Union Valley Reservoir. With the exception of Folsom Lake, Union Valley is the largest in the American River watershed, storing of water. The Upper American River Project produces 1.8 billion kilowatt hours in an average year, enough for about 20 percent of Sacramento's electricity needs. The SMUD plants are run on a peaking basis, although recreational boating and environmental flow requirements constrain their operation slightly.