GeographyThe Gila River has its source in western New Mexico, in Sierra County on the western slopes of the in the . It flows southwest through the and the , then westward into Arizona, past the town of . After flowing along the southern slope of the Gila Mountains in Graham County through a series of canyons, the Gila is impounded by in south of . It emerges from the mountains into the valley southeast of Phoenix, Arizona, where it crosses the Gila River Indian Reservation as an intermittent stream due to large irrigation diversions, primarily at the Hayden Ashurst Diversion Dam. Well west of Phoenix, the river bends sharply southward along the Gila Bend Mountains, then it swings westward again near the town of Gila Bend, Arizona, Gila Bend. It flows southwestward between the Gila Mountains (Yuma County), Gila Mountains to the south and the Laguna Mountains (Arizona), Languna and Muggins Mountains, Muggins ranges to the north in Yuma County, Arizona, Yuma County, and finally it empties into the Colorado at Yuma, Arizona. The Gila is joined by many tributaries, beginning with the East and West Forks of the river, which combine to form the main stem near Gila Hot Springs, New Mexico, Gila Hot Springs in New Mexico. Above Safford, it is joined by the San Francisco River (central Arizona), San Francisco River and the intermittent San Simon River. Further downstream, it is joined by the San Carlos River from the north in San Carlos Lake. At Winkelman, Arizona, it picks up the San Pedro River (Arizona), San Pedro River and then is joined by the Santa Cruz River (Arizona), Santa Cruz River south of Casa Grande, Arizona, Casa Grande. The Salt River (Arizona), Salt River, its main tributary, joins in the Phoenix metropolitan area, and further west the Gila receives its last two major tributaries, the Agua Fria River, Agua Fria and Hassayampa River, Hassayampa Rivers, from the north. Although the Gila River flows entirely within the United States, the headwaters of two tributaries – the San Pedro and Santa Cruz River (Arizona), Santa Cruz Rivers – extend into Mexico. About , or 2.8% of the Gila's watershed, is in Mexico. A further or 5.7% lies within New Mexico, while the remaining majority, or 91.5%, is in Arizona.
HistoryA band of Pima people, Pima (autonym "Akimel O'odham", river people), the Keli Akimel O'odham (Gila River People), have lived on the banks of the Gila River since before the arrival of Spanish explorers. Popular theory says that the word "Gila" was derived from a Spanish contraction of Hah-quah-sa-eel, a Yuma language, Yuma word meaning "running water which is salty". Their traditional way of life (''himdagĭ'', sometimes rendered in English as Him-dak) was and is centered at the river, which is considered holy. Traditionally, sand from the banks of the river is used as an exfoliant when bathing (often in rainstorms, especially during the monsoon). Indigenous peoples such as the Hohokam were responsible for creating large, complex civilizations along the Middle Gila River and Salt River between 600 and 1450 AD. These native civilizations depended largely on irrigated agriculture, for which they constructed over of canals. The upper Gila was inhabited by the Mogollon culture over most of the same time period, in settlements like those at in the later period. The first European to see the Gila River was possibly Spain, Spanish explorer and missionary Juan de la Asunción. Asunción reached the Gila in 1538 after traveling northwards along one of its tributaries, either the San Pedro or Santa Cruz. In 1540, Hernando de Alarcón sailed up the Colorado and Gila Rivers; maps drawn by his expedition show the river as the ''Miraflores'' or ''Brazos de la Miraflores''. During the Mexican–American War, General Stephen Watts Kearny marched 100 cavalrymen from the 1st U.S. Dragoons along the Gila River in November 1846. This detachment was guided by Kit Carson. The Mormon Battalion followed Kearny's troops, building a wagon trail roughly following the river from December 1846 to January 1847. After the Treaty of Guadalupe-Hidalgo in 1848, the Gila River served as a part of the border between the United States and Mexico until the 1853 Gadsden Purchase extended American territory well south of the Gila. The confluence of the Gila with the Colorado River was also used as a reference point for the southern border of California. Beginning in 1871, mainly Mormon settlers populated the Gila River valley around present-day Phoenix, using the Gila, Salt, and San Pedro Rivers for irrigation and establishing at least six major settlements. In 1944, 25 German prisoner of war, prisoners of war pulled off the Great Papago Escape, largest and most spectacular escape from an American compound during the war, digging a tunnel out of the Navy’s Papago Park Prisoner of War Camp in Arizona. All of the men were eventually captured, though some remained at large for more than a month. Among the last to be captured were three German soldiers who had based their audacious but ill-fated escape plans on a stolen highway map of Arizona, which showed the Gila River leading to the Colorado River, which in turn led to Mexico. Devising a scheme to flee by water, the Germans constructed a collapsible kayak under the noses of their American captors, tested it in a makeshift pool within the prison compound, then sneaked it out through the tunnel. Their plan was perfect – except for the map. The Gila, shown as a healthy blue waterway, turned out to be little more than a dry rut.
Dams and diversionsThe only major dam on the Gila River is Coolidge Dam, southeast of Globe, Arizona, which forms San Carlos Lake. The Painted Rock Dam crosses the Gila near Gila Bend, although the river is a transient one at that point. The majority of the water is diverted at the Ashurst-Hayden Diversion Dam near Florence, Arizona. A number of minor diversion dams have been built on the river between the Painted Rock Dam and the Coolidge Dam, including the Gillespie Dam, which was breached during a flood in 1993. Many dams have been built on tributaries to the Gila River, including Theodore Roosevelt Dam, Horse Mesa Dam, and Mormon Flat Dam on the Salt River (Arizona), Salt River, New Waddell Dam on the Agua Fria River, and Bartlett Dam on the Verde River. Many major dams in the Gila River system were built and operated by the U.S. Bureau of Reclamation, which also constructed most of the large dams throughout the Colorado River basin. Others, such as Coolidge Dam, are owned by local water supply agencies, irrigation districts, or Native American tribes. The Gila River and its main tributary, the Salt River, were both perennial streams carrying large volumes of water – the Gila was once navigable by large riverboats from its mouth to near Phoenix, and by smaller craft from Phoenix nearly to the Arizona-New Mexico border – until irrigation and municipal water diversions turned both into usually dry rivers which carry water only after local downpours create flooding. Below Phoenix to the Colorado River, the Gila is usually either a trickle or completely dry, as is also the lower Salt from Granite Reef Diversion Dam downstream to the Gila, but both rivers can carry large volumes of water following rainfall. The historic width of the Gila River varied from with a depth of . Its natural discharge was roughly per year, with a mean flow of about at the mouth. The river's present discharge near the mouth is less than per year, with an average flow of just . Overdraft from the Gila River system prompted the construction of the Central Arizona Project, which delivers some annually from the Colorado River to supplement water supplies in the basin. The upper Gila River, including its entire length within New Mexico, is a free-flowing one. Recent efforts to allow for damming or otherwise diverting this stretch have met with stiff political resistance, having been named as one of the nation's most endangered rivers due to proposed dam projects such as Hooker Dam. During his time in office, former New Mexico Governor Bill Richardson had promised to block any such attempt during his term, and he had even considered pushing for a statutory prohibition against any such projects on the state's portion of the river.
RecreationThe Gila River between Virden, New Mexico, and Solomon, Arizona, is navigable during spring snowmelt and after summer and autumn storms. The river passes through many scenic canyons and stretches of Class I to III whitewater. Due to its desert surroundings, the river is characterized by erratic flows and flash floods that reach high peaks and drop off just as quickly. The Gila's Salt River tributary has even more difficult whitewater, ranging up to Class IV in places, and often has higher and more dependable flows than the Gila. Boating and fishing are popular on San Carlos Lake and other basin reservoirs, including Lake Pleasant Regional Park, Lake Pleasant and Theodore Roosevelt Lake. The river system has 36 fish species,Benke and Cushing, p. 531 including largemouth bass, Centrarchidae, sunfish, channel catfish, flathead catfish, and Gila trout ''(Oncorhynchus gilae gilae)''.
Variant namesThe Gila River has also been known as: * Akee-mull * Apache de Gila * Brazo de Miraflores * Cina`ahuwipi (Chemehuevi language) * Hah-quah-sa eel (Yuma language) * Hela River * Jila River * Rio Azul * Rio Gila * Rio de las Balsas * Rio del Nombre Jesus * Rio del los Apostoles * Zila River * Xila River * Keli Akimel
See also*Gila and Salt River Meridian *Gila River War Relocation Center *List of Arizona rivers *List of New Mexico rivers *List of longest rivers of the United States (by main stem) *List of tributaries of the Gila River *Needle's Eye Wilderness *San Francisco River (central Arizona), San Francisco River *San Pedro River (Arizona), San Pedro River *Santa Cruz River (Arizona), Santa Cruz River