Granite Reef Diversion Dam



The Granite Reef Diversion Dam is a concrete diversion dam located 22 mi Northeast of Phoenix, Arizona. It impounds the Salt River for irrigation purposes. If it were to overflow, more than half of the Yavapai Reservation would be flooded.

The dam diverts nearly all water from the Salt River into the Arizona and South Canals, which serve metropolitan Phoenix with irrigation and drinking water. The Salt River below Granite Reef is usually dry except following consistent and heavy upstream precipitation. When upstream lakes are full, minor and moderate releases are accomplished via floodgates at either end of the dam. The dam is designed to be overtopped by major releases, which can occur every 10 to 40 years.

The dam is 1128 ft long, 29 ft high. Its volume is 35000 cuyd.

The United States Bureau of Reclamation built the dam between 1906 and 1908 to replace Arizona Dam washed out in 1905. It is operated by the Salt River Project, an electric cooperative.