Instruct: Given a question, retrieve relevant documents that answer the question.
Query: Where does the American River originate?
The American River is fed by its North, Middle, and South forks, which are located in El Dorado County, Placer County, and Sacramento County. The river's three forks originate in the Tahoe and Eldorado National Forests. The North and Middle Forks join near Auburn, and continue downstream as the North Fork, although the Middle Fork carries a higher volume of water. The North and South Forks join in Folsom Lake. All three forks are known for their verdant canyons, forested ridges, massive rock formations, trails, backcountry winter adventuring among snowy peaks, fishing and white water rafting. There are various fish species that live within the American River such as Chinook Salmon and Steelhead Trout.
Historically, the American River, like many other rivers in California, were modified by the dams of beavers, until European trappers removed many of the beavers from their native habitat for their fur. Since the California Gold Rush was centered in an area that included the American River basin, it was one of the earlier California rivers to be populated, beginning at Leidesdorff Ranch, owned by William Leidesdorff. Water was used to drive grist mills. Gold miners dredged the riverbed and constructed diversion dams for hydraulic mining. Mining activity caused sediment and mercury waste to accumulate in the rivers. The Natoma Company completed its Folsom Powerhouse in 1895 and began delivering power 22 miles (35 km) away to the city of Sacramento to power a streetcar system.
The Stones River is composed of three major forks: the West, Middle, and East forks. The West Fork, long, rises in southernmost Rutherford County near the Bedford County line. The upstream portion of its course runs roughly parallel to U.S. Highway 231. The Middle Fork, long, rises in an area of low hills, or knobs, also near the line with Bedford County, near Hoovers Gap, an important troop movement route during the American Civil War. It flows roughly parallel to, but west of, Interstate 24 and U.S. Highway 41, and is met by the West Fork near State Route 99. The East Fork is the longest, at ; it rises in Cannon County on Short Mountain, an outlier of the Cumberland Plateau, and flows through Woodbury, the county seat. This stream is roughly paralleled by U.S. Route 70S.
The All-American Canal is an 80-mile (130 km) long aqueduct, located in southeastern California. It conveys water from the Colorado River into the Imperial Valley and to nine cities. It is the Imperial Valley's only water source, and replaced the Alamo Canal, which was located mostly in Mexico. The Imperial Dam, about 30 miles (48 km) northeast of Yuma, Arizona on the Colorado River, diverts water into the All-American Canal, which runs to just west of Calexico, California before its last branch heads mostly north into the Imperial Valley. Five smaller canals branching off the All American Canal move water into the Imperial Valley. These canal systems irrigate up to 630,000 acres (250,000 ha) of crop land and have made possible a greatly increased crop yield in this area, originally one of the driest on earth. It is the largest irrigation canal in the world, carrying a maximum of 26,155 cubic feet per second (740.6 m/s). Agricultural runoff from the All American Canal drains into the Salton Sea.
Nine rivers in this list cross international boundaries or form them. Four—the Yukon, Columbia, Porcupine, and Kootenay—begin in Canada and flow into the United States. Five—the Milk, Pend d'Oreille, Saint Lawrence, Red, and Saint John—begin in the United States and flow into Canada. Of these, the Milk and the Kootenay cross the international border twice, the Milk leaving and then re-entering the United States, the Kootenay leaving and then re-entering Canada. The drainage basins of these nine rivers extend into both countries; in addition, the drainage basins of six others—the Fraser, Assiniboine, South Saskatchewan, Saskatchewan, Nelson, and Winnipeg—extend into the United States even though their main stems flow entirely within Canada.
The Sacramento River is the principal river of Northern California in the United States, and is the largest river in California. Rising in the Klamath Mountains, the river flows south for before reaching the Sacramento–San Joaquin River Delta and San Francisco Bay. The river drains about in 19 California counties, mostly within the fertile agricultural region bounded by the Coast Ranges and Sierra Nevada known as the Sacramento Valley, but also extending as far as the volcanic plateaus of Northeastern California. Historically, its watershed has reached as far north as south-central Oregon where the now, primarily, endorheic (closed) Goose Lake rarely experiences southerly outflow into the Pit River, the most northerly tributary of the Sacramento.
Below Rio Vista, the lower Sacramento River is rejoined by the Deep Water Ship Channel and the Yolo Bypass and curves southwest along the base of the Montezuma Hills, forming the border of Solano and Sacramento Counties. This part of the river is dredged for navigation by large oceangoing vessels and averages three-quarters of a mile (1.2 km) across. North of Antioch and Pittsburg, the Sacramento and San Joaquin Rivers join at the head of Suisun Bay, marking the official end of both rivers. The combined waters flow west through Suisun Bay and the Carquinez Strait into San Pablo Bay and San Francisco Bay, joining the Pacific at the Golden Gate.
The main source rivers include the Sacramento River from the north, the San Joaquin from the southeast, and the Calaveras and Mokelumne Rivers from the east. The Calaveras and Mokelumne are both tributaries of the San Joaquin River. The Sacramento and San Joaquin Rivers join at the western end of the Delta near Pittsburg, at the head of Suisun Bay, although they are linked upstream by the Georgiana Slough, which was first used by steamboats in the 19th century as a shortcut between Sacramento and Stockton. The southwestern part of the Delta is also transected by the Middle River and Old River, former channels of the San Joaquin. These rivers transport more than of water through the Delta each year – about 50 percent of all California's runoff.
The Zuni (Zuñi) River is a tributary of the Little Colorado River in the southwestern United States. It has its origin in Cibola County, New Mexico, in the Zuñi Mountains at the Continental Divide. The river flows off the western slopes of the Zuñi Mountains in a generally southwesterly direction through the Zuni Indian Reservation to join the Little Colorado River in eastern Arizona. The Zuni River is approximately long, and has a drainage basin in New Mexico of approximately .
North of Salmon, the river is joined by the North Fork, before turning west into over of continuous canyons through the Salmon River and Clearwater Mountains – some of the most rugged and isolated terrain in the contiguous United States. Exhibiting upwards of of vertical relief, the Salmon River canyons are some of the deepest in the U.S., surpassing the Grand Canyon and second only to the Snake River's Hells Canyon on the Idaho–Oregon border. Here, the river is joined by its two largest tributaries, the Middle Fork and South Fork. Ten miles (16 km) downstream (west) of its confluence with the Middle Fork, the Salmon River becomes the dividing line for the two time zones in Idaho: Mountain time to the south, Pacific time to the north, bisecting the state at approximately 45½ degrees north latitude.
Union Falls ht. is a waterfall on Mountain Ash Creek, a tributary of the Fall River in the "Cascade Corner" (southwest) of Yellowstone National Park. It is the second highest waterfall in Yellowstone exceeded in height only by the lower Yellowstone Falls. The falls got its name from members of the Arnold Hague Geological Surveys sometime between 1884-86. Geologist J.P. Iddings claims the name derives from the fact that a tributary of Mountain Ash Creek joins at the very brink of the falls, thus "Union Falls". Access to the falls is via the Mountain Ash Creek trail and the Grassy Lake Road.
Second only to the Columbia River on the west coast of the United States in Chinook salmon runs, the Sacramento and its tributaries once supported a huge population of this fish. Millions of salmon once swam upstream to spawn in the Sacramento; as recently as 2002 eight hundred thousand fish were observed to return to the river. The Sacramento and San Joaquin River systems are home to the southernmost existing run of chinook salmon in North America.
In 1818, the Quapaw tribe ceded all its land north of the Canadian to the United States, thus making this river the effective southern boundary of the new nation. In 1825, the Osage ceded their claims to land along the river. The Canadian was designated as the boundary between the Creek-Seminole lands on the north side and the Choctaw (and later the Chickasaw) on the south side. Major Stephen H. Long led an expedition up the Canadian River in 1821. He proclaimed the land along the river as the "Great American Desert." Despite this assessment, trading posts were established along the river, starting with Edwards' Post at the mouth of Little River. Camp Holmes was established by Colonel Henry Dodge's Dragoons in 1834. Captain Nathan Boone led a dragoon troop up the river to the 100th Meridian, which was then the western border of the United States.
The Columbia drains an area of about . Its drainage basin covers nearly all of Idaho, large portions of British Columbia, Oregon, and Washington, ultimately all of Montana west of the Continental Divide, and small portions of Wyoming, Utah, and Nevada; the total area is similar to the size of France. Roughly of the river's length and 85 percent of its drainage basin are in the US. The Columbia is the twelfth-longest river and has the sixth-largest drainage basin in the United States. In Canada, where the Columbia flows for and drains , the river ranks 23rd in length, and the Canadian part of its basin ranks 13th in size among Canadian basins. 
The Columbia shares its name with nearby places, such as British Columbia, as well as with landforms and bodies of water.
The Concho River has three primary feeds: the North, Middle, and South Concho Rivers. The North Concho River is the longest fork, starting in Howard County and traveling southeast for until merging with the South and Middle forks near Goodfellow Air Force Base in San Angelo, Texas. The combined branches of the river flow east about until it eventually empties into the Colorado River within the waters of the O.H. Ivie Lake about east of Paint Rock, Texas.
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases a river flows into the ground and becomes dry at the end of its course without reaching another body of water. Small rivers can be referred to using names such as stream, creek, brook, rivulet, and rill. There are no official definitions for the generic term river as applied to geographic features, although in some countries or communities a stream is defined by its size. Many names for small rivers are specific to geographic location; examples are "run" in some parts of the United States, "burn" in Scotland and northeast England, and "beck" in northern England. Sometimes a river is defined as being larger than a creek, but not always: the language is vague.
Cow Creek is a tributary of the Sacramento River in Shasta County, California. About long measured to its longest source, it drains a hilly, rural region at the northern end of the Sacramento Valley east of Redding. The creek begins at Millville at the confluence of Old Cow and South Cow Creek and flows west to Junction, where it turns south, joining the Sacramento near Anderson. Despite its name, Cow Creek is closer in size to a river, especially in winter when it is prone to large flash floods, accounting for up to 21 percent of the Sacramento's peak flows at Red Bluff.
From Keswick Dam south to Red Bluff, California, the Sacramento River is relatively narrow and deep with some areas of broader alluvial floodplain. Most of the Chinook-salmon-spawning habitat in the river is located in this reach. The variability and magnitude of natural seasonal flows of the Sacramento River have been significantly altered for the purposes of irrigation and flood control. The dams and diversions operated by the Central Valley Project and local irrigation districts control much of the flow in the Sacramento River. Since 1993, to protect the holding and spawning of winter-run Chinook salmon, Reclamation has been required to manage cold-water reservoir storage and releases to maintain daily average water temperatures at or below between Keswick Dam and compliance locations between Balls Ferry and Bend Bridge, from May 15 to September 30.
As the river continues south it approaches the Sacramento metro area, the largest population center in the watershed. Sacramento International Airport is located on the east bank of the river near Fremont. Near downtown Sacramento it receives the American River from the east, then passes under the historic Tower Bridge and Interstate 80. The California State Capitol sits less than half a mile (0.8 km) east of the river where the Tower Bridge crosses it. Shortly downstream, the Port of Sacramento is located on the west side of the Sacramento, connected to the river by a lock. The Sacramento River Deep Water Ship Channel provides access to the port from the Pacific, bypassing about of the winding lower Sacramento. The channel runs parallel to the Sacramento several miles to the west, and also forms the eastern boundary of the Yolo Bypass. The manually operated Sacramento Weir, located across from downtown Sacramento on the west side of the river, serves to relieve floodwater pressure from the American River by allowing it to drain west into the Yolo Bypass instead of continuing down the Sacramento River.
Downstream of Sacramento, the river enters the Sacramento–San Joaquin River Delta, a vast tidal estuary and inverted river delta of over which receives the entire run-off of the Central Valley, a region covering a third of California. The Sacramento is by far the largest contributor of fresh water to the Delta; in an average year, it accounts for more than 80 percent of the fresh water inflow. At Walnut Grove, the manmade Delta Cross Channel connects the Sacramento to the Mokelumne River channel, allowing a portion of the water to be pumped south toward Clifton Court Forebay, the receiving reservoir for the main CVP and State Water Project aqueducts which irrigate millions of acres and supply water to over 23 million people in the San Joaquin Valley, the San Francisco Bay Area and Greater Los Angeles. Although river levels are tidally influenced here and occasionally as far north as Verona, the water stays fresh in all but the driest years. Saltwater intrusion from the Pacific Ocean was one of the main reasons for the construction of the federal Central Valley Project (CVP), whose dams maintain a minimum flow in the Sacramento to keep seawater at bay.
The Four Corners is a region of the United States consisting of the southwestern corner of Colorado, southeastern corner of Utah, northeastern corner of Arizona, and northwestern corner of New Mexico. The Four Corners area is named after the quadripoint at the intersection of approximately 37° north latitude with 109° 03' west longitude, where the boundaries of the four states meet, and are marked by the Four Corners Monument. It is the only location in the United States where four states meet. Most of the Four Corners region belongs to semi-autonomous Native American nations, the largest of which is the Navajo Nation, followed by Hopi, Ute, and Zuni tribal reserves and nations. The Four Corners region is part of a larger region known as the Colorado Plateau and is mostly rural, rugged, and arid. In addition to the monument, commonly visited areas within Four Corners include Monument Valley, Mesa Verde National Park, Chaco Canyon, Canyons of the Ancients National Monument and Canyon de Chelly National Monument. The most populous city in the Four Corners region is Farmington, New Mexico, followed by Durango, Colorado.
The Castlereagh rises 20 km west of Coonabarabran in the heart of the Warrumbungle mountains at an elevation of about 850 metres. From its commencement upstream in the mountains the river initially flows east through the town of Coonabarabran. It then arcs round south and southwesterly to the village of Ulamambri, then south to Binnaway, and SSW to the small town of Mendooran which lies at the eastern side of the river's hook-shape. From here the Castlereagh flows in a westerly direction at the flattened bottom of the hook and then turns north-westerly towards the town of Gilgandra. From Gilgandra it continues to run northwesterly across the plains through Gulargambone and Coonamble, then continuing across expansive plains, with no urban centres, where elevations are less than 200m, until it joins the Macquarie River at its uppermost reaches beyond the Macquarie Marshes. Its confluence with the Macquarie is about 65 km SW of Walgett. Not far from the Castlereagh/Macquarie confluence the Macquarie itself joins the Barwon River at a place about halfway between Walgett and Brewarrina.
The South Fork is long. It originates at Echo Summit near Echo Lake south of Lake Tahoe in El Dorado County, just south of where U.S. Route 50 makes a sharp curve northward to descend into Tahoe Valley. The South Fork has multi-use recreational areas, including the Rubicon Trail for motorized adventuring and whitewater rafting venues. The South Fork also features the historic town of Coloma, where the California Gold Rush began in 1848. Trout fishing and recreational gold panning are popular activities on the South Fork.
The American River Parkway is a 23-mile stretch along the American River and includes about 5,000 acres of embankment between the Nimbus Fish Hatchery and where the American River and the Sacramento River converge. The Sacramento City Regional Parks owns most of the land that is operated by the American River Parkway. This area serves the citizens of Sacramento and visitors from away with access to the river and parks, picnic areas, biking and jogging paths, trails for hiking, and habitat for fish and wildlife.
The South Fork of the Rubicon River originates about a mile southeast of Loon Lake. It flows southwest for several miles until it is joined by Gerle Creek, and then travels west to its confluence with the Rubicon River. The river slowly changes course and eventually heads northwest again, finally, joining the Middle Fork of the American River about northeast of Auburn. The Middle Fork meets the North Fork of the American River in the Auburn State Recreation Area below the Foresthill Bridge, and flows into Folsom Lake.
The river is formed by the confluence of the American River and Red River in the Nez Perce National Forest at an elevation of . The roughly American River rises at and flows generally south to the confluence, while the northwest flowing Red River, rising at , is about long. The American River is sometimes considered part of the main stem. From the confluence the South Fork flows west through a canyon followed by Idaho State Highway 14, receiving the Crooked River from the left and Newsome Creek from the right before reaching Golden, where it receives Tenmile Creek from the left. Further west the river receives Johns Creek from the left, Meadow Creek from the right and Mill Creek from the left, and the gorge deepens to a maximum of some as the river swings north near Grangeville. From there the river flows generally north, past Harpster and Stites, before reaching its mouth on the Clearwater at Kooskia, at an elevation of .