American River

The American River (Río de los Americanos in the Mexican period) located in the US state of California, has a prominent place in United States history for being the site of Sutter's Mill, where gold was found in 1848, leading to the California Gold Rush. It runs from the Sierra Nevada mountains through Sacramento and flows into the Sacramento River on its way to San Francisco Bay. It is known for its whitewater rapids.

The American River is divided into the North, Middle, and South Forks. The North fork flows under the Foresthill Bridge just prior to the confluence with the Middle Fork about 3 miles (5 km) from Auburn, California. From there, the combined river meanders down past the proposed site of the controversial Auburn Dam, and onward to Folsom Lake. These rivers are popular for their verdant canyons, fishing and white water rafting. Below Folsom Lake, the river passes through an urbanized area but is buffered by a riparian park, the American River Parkway, that runs 23 miles (37 km) from Folsom Lake to the river's confluence with the Sacramento River. The American River Parkway incorporates the Jedediah Smith Memorial Trail, a meandering, uninterrupted 32-mile cycle path which hugs the river bank from Old Sacramento to Folsom Lake.

The American River and its tributaries (like most of California's rivers) are extensively dammed and diverted for hydroelectricity production. Bunch Creek is one of the tributaries of the North Fork of the American River. Since the California Gold Rush was centered along the American river, it was one of the earlier California rivers to be populated and used for milling. By the end of the nineteenth century some of these former mill sites were converted to some of the earliest hydroelectric plants, with Folsom State Prison using the river to generate electricity in 1893. The Natoma Company completed its Folsom Powerhouse and began delivering power 22 miles (35 km) away to the city of Sacramento by 1895. Today, the five power plants on the Middle Fork are owned by the Placer County Water Agency (PCWA) and the Sacramento Municipal Utility District (SMUD) owns eight plants on the South Fork. The SMUD plants are run on a peaking basis, although reservoir flood control capacity and minimum flow requirements impose some constraints on their operation. The Pacific Gas and Electric Company (PG&E) owns the Chili Bar power plant on the South Fork downstream from SMUD's plants. The U.S. Bureau of Reclamation (USBR) has two hydroelectric plants downstream at Folsom Dam and Nimbus Dam. The Bureau of Reclamation operates Nimbus as a base load plant and Folsom as an intermediate plant.