Formed by faulting, the basin trends north- south and is drained by Tonto Creek and its tributaries. The basin is bounded on the north by the Mogollon Rim, on the east by the Sierra Ancha Mountains, and on the west by the Mazatzal Mountains. Elevations range from 7,800 feet above mean sea level in the Mazatzal Mountains to 2,200 feet above mean sea level at Roosevelt Lake where Tonto Creek terminates. All four general rock units in the Tonto Creek basin contain some groundwater reserves. The amount of groundwater available varies widely, and generally depends on the unit's composition and structure.
Most wells are low-yield domestic and stock wells.
Precipitation falling in the higher elevations of the Tonto Creek basin sustains the base flow of Tonto Creek. The two major aquifers, the alluvium and the basin-fill sediments, receive most of their recharge by infiltration from Tonto Creek.