Iriri River Iriri River The Iriri River () is a large tributary of the Xingu River in Brazil, in the state of Pará. It is long making it the 116th longest river in the world (with Krishna River, India) and the 15th longest in the Amazon basin. The headwaters are the traditional home of the Panará people. The river rises in the Nascentes da Serra do Cachimbo Biological Reserve, a strictly protected conservation unit established in 2005 in the Serra do Cachimbo. It is one of the headwaters of the Xingu River. It flows for before joining the Xingu, running through the
American River habitat. Nimbus Dam is downstream from Folsom Dam and helps to stabilize peaking power releases from Folsom Dam, and divert water into the Folsom South Canal for irrigation. 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