Gila

Gila (hē`lə), river, 630 mi (1,014 km) long, rising in the mountains of W N.Mex. and flowing W across Ariz. to the Colorado River at Yuma, Ariz.; the San Francisco River is its main tributary. The Gila valley was occupied by the ancestors of the Pima and Papago ethnic groups, who farmed the region by irrigation. The ruins of their dwellings are preserved in Casa Grande Ruins and Gila Cliff Dwellings national monuments (see National Parks and Monuments, table). In the river's headwater region are Gila National Forest and the government-preserved "unimproved" Gila Wilderness Area. The Gila and its tributaries have many dams to provide flood control, hydroelectricity, and water for irrigation in the arid Southwest (see Salt River valley). Coolidge and Painted Rock dams are the largest dams on the Gila River. Gila monsters (poisonous reptiles) are numerous in the Gila valley.

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Gila 

a river in the southwestern USA, a left tributary of the Colorado River. The Gila is 1,040 km long and drains an area of 150,000 sq km. It rises in the mountains at the southern margin of the Colorado Plateau and flows through a canyon-like valley in its upper and middle courses. The river is fed by rain. In its lower course, in the Gila Desert, it is usually dry. The Gila has a mean flow rate of 0.6 cu m per sec. The Coolidge and Gillespie dams have been built on the river’s middle course.