The upper Gila River watershed is located in southwestern New Mexico and in southeastern Arizona above Coolidge Dam at San Carlos Reservoir. The watershed drains a total of 12,890 square miles which represents only one-fifth of the entire Gila watershed. The river originates in the Mogollon Mountains in western New Mexico and flows easterly through Arizona before flowing into the San Carlos Reservoir. In Arizona, the upper watershed drains 7,430 square miles and is within the Morenci, Duncan Valley, Bonita Creek, and Safford groundwater basin boundaries. Major tributaries of the Gila River within the area are the San Francisco River, Eagle Creek, Bonita Creek, San Simon Creek, and the San Carlos River.
Agriculture is the major use of surface water in the watershed.
Irrigation water is obtained from the Gila River at several diversion points and from wells pumping groundwater. Diversions from the river above Coolidge Dam have been regulated by the Gila Decree since 1936. The Gila River is intermittent as it enters Arizona from New Mexico through the Duncan-Virden Valley. The river does maintain a 35-mile perennial stretch beginning approximately 20 miles downstream from where it enters Arizona. Table 26 lists all perennial streams reaches in the upper Gila watershed.