The Salt River is a tributary of the Gila River, it is formed at the confluence of the Black and White Rivers.  The Salt River flows 200 miles (or 320 kilometers) west and empties into the Gila River just southwest of Phoenix, Arizona.  The Salt River is part of the Colorado River drainage basin.  A system of dams forms a chain of lakes which provides hydroelectric power.  In the pre-Columbian times the river was used by the Hohokam Indians who constructed systems or irrigation canals for crops and to move water more inland from the river.