Gila River 3.99

The Gila River is a 649mi tributary of the Colorado River flowing through New Mexico and Arizona in the United States. The river drains an arid watershed of nearly 60000mi2 that lies mainly within the U.S. but also extends into northern Sonora, Mexico. Indigenous peoples have lived along the river for at least 2,000 years, establishing complex agricultural societies before European exploration of the region began in the 16th century. However, Euro-Americans did not permanently settle the Gila River watershed until the mid-19th century.During the 20th century, human development of the Gila River watershed necessitated the construction of large diversion and flood control structures on the river and its tributaries, and consequently the Gila now contributes only a small fraction of its historic flow to the Colorado. The historic natural discharge of the river is around 1900 cfs, and is now only 247 cfs. These engineering projects have transformed much of the river valley and its surrounds from arid desert to irrigated land, and supply water to over five million people that live in the watershed.GeographyThe Gila River has its source in western New Mexico, in Sierra County on the western slopes of Continental Divide in the Black Range. It flows southwest through the Gila National Forest and the Gila Cliff Dwellings National Monument, then westward into Arizona, past the town of Safford. After flowing along the southern slope of the Gila Mountains in Graham County through a series of canyons, the Gila is impounded by Coolidge Dam in San Carlos Lake south of Peridot.