The San Juan River originates in southern Colorado and runs along the southern slope of the San Juan Mountains west of the Continental Divide in southwestern Colorado and into the state of New Mexico. Navajo Dam is located on the meandering San Juan River in northeastern New Mexico about 34 miles (55 kilometers) east of Farmington. After flowing through New Mexico and Utah, the San Juan joins the Colorado River at Lake Powell.
The first proposal for a major San Juan River dam was made in 1930 based on investigations made in the vicinity that dated back to 1904. Because the estimated construction costs for a dam were significant, authorization for Navajo Dam was delayed until it could be incorporated into the revenue-sharing features of the Colorado River Storage Project. Navajo Dam is one of four initial storage units of the Colorado River Storage Project.
Construction of Navajo Dam began in July 1958 and it was dedicated on September 15, 1962. The nearly three-quarter mile long dam stands 402 feet (123 meters) high with a crest length of 3,648 feet (1,112 meters). Nearly 26 million cubic yards (19.8 million cubic meters) of selected cobbles, gravel, sand, and clay taken from 16 borrow areas beside the San Juan River and along valley benches, were used in construction of the rolled earthfill embankment.
The main section of Navajo Dam’s spillway is 138 feet (42 meters) wide with a capacity of 34,000 cubic feet per second (254,320 gallons per second) available for use if the ability to quickly evacuate water becomes necessary. However, under normal conditions, water is released into the San Juan River downstream via the outlet works primarily for irrigation, municipal, and industrial purposes and hydropower generation by the city of Farmington, New Mexico.
Navajo Reservoir extends 35 miles (56 kilometers) up the San Juan River, 13 miles (21 kilometers) up the Pine River, and 4 miles (6 kilometers) up the Piedre River. When full, the surface area of the reservoir is 15,610 acres (6,317 hectares) with a total capacity of 1,708,600 acre-feet (2,107 million cubic meters), and a maximum depth of 388 feet (118 meters) at the dam. In addition to regulating the flows of the San Juan River, Navajo Reservoir is the principal storage reservoir for the Navajo Indian Irrigation Project (NIIP).
Water is released through a tunnel into an aqueduct for use on the NIIP to irrigate about 110,000 acres (44,515 hectares) of land on the Navajo Indian Reservation. The Colorado River Storage Project Act of April 11, 1956 which authorized construction of Navajo Dam and Reservoir did not provide for construction of a powerplant at Navajo Dam. However, a powerplant was later constructed by the city of Farmington, New Mexico under a license issued October 15, 1985 by the Federal Energy Regulatory Commission under the authority of the Federal Power Act of June 10, 1920. The city of Farmington owns and operates the powerplant in coordination with Reclamation who is responsible for operating Navajo Dam.