Water Storage and Delivery

The History of the Colorado River Storage Project

Investigations of the means to develop the waters of the Upper Colorado River system were started by the Reclamation Service in 1902, the year of its inception. Since 1902, Reclamation has constructed 25 projects to utilize water in the Upper Colorado River Basin. The CRSP was envisioned at the time of the Colorado River Compact of 1922. In dividing Colorado River water between the upper and lower Colorado River basins, the compact set aside for consumption in the upper basin 7.5 million acre-feet of water each year.

However, this allocation is contingent upon the upper basin delivering to the lower basin not less than 75 million acre-feet of water in any consecutive 10 year period and delivering additional water for use in Mexico under certain circumstances. The dividing point between the two basins is at Lee Ferry, near the northern border of Arizona.

Water allocated to the upper basin was further apportioned to the individual states of Arizona, Colorado, New Mexico, Utah, and Wyoming by the Upper Colorado River Basin Compact of 1948.

Spring runoff from the Colorado River is extremely erratic, varying from four to 22 million acre-feet annually. In prolonged dry periods, there is not enough water to permit the upper basin to increase its use of water under the 1922 compact and, at the same time, make the required deliveries to the lower basin. In wetter periods, however, flows are more than sufficient for these purposes. To weather the dry hydrologic cycles, large storage reservoirs, that could be filled when flows are high and can provide additional water when needed for compact fulfillment, were required.

Favorable sites for such reservoirs were found in the deep canyons of the Colorado River and its principal tributaries in the upper basin. A plan for the CRSP, including a series of dams and reservoirs to provide storage capacity in combination with power development and other purposes, was presented to Congress in a Bureau of Reclamation report in 1950. An initial group of participating projects that would develop water for irrigation and other purposes in the upper basin was described in the 1950 report.

Development of the Colorado River Storage Project

Construction of four storage units of the Colorado River Storage Project and 11 participating projects was authorized by the act of April 11, 1956 Additional projects have been added since the original legislation was adopted.

The initial act authorized features developments included:

Glen Canyon Unit on the Colorado River in Arizona and Utah
Flaming Gorge Unit on the Green River in Utah and Wyoming
Navajo Unit on the San Juan River in New Mexico and Colorado
Curecanti Unit, consisting of three dams on the Gunnison River in Colorado. In November 1980, this unit was renamed the Wayne N. Aspinall Storage Unit in honor of former Congressman Aspinall, a strong advocate of water resource development in the West.

Intended Purposes of the Colorado River Storage Project

The CRSP was authorized to provide for the comprehensive development of the Upper Colorado River Basin. The project furnishes the long-time regulatory storage needed to permit states in the upper basin to meet their flow obligation at Lee Ferry, Arizona, as defined in the Colorado River Compact, and still utilize their apportioned water for beneficial purposes. The storage reservoirs formed by the four initial units of the CRSP have a total live capacity of 30.6 million acre-feet.

Glen Canyon Dam and Lake Powell are the primary long-term carryover storage features of the CRSP. By itself, Lake Powell provides more storage capacity than all other storage features of the project combined. Total capacity for Lake Powell, when entirely full, is 26.2 million acre-feet, and the live capacity is 24.3 million acre-feet. At normal water surface elevation, the reservoir has a length of 186 miles and a surface area of 161,390 acres.

Glen Canyon Dam enables both the upper basin and the lower basin systems to operate the Colorado River more effectively. Glen Canyon Dam is integral in meeting the water delivery obligations established under the Law of the River by meeting the authorized purposes of the CRSP, including irrigation, flood control, municipal and industrial water supply and power generation.

Key Benefits of the Colorado River Storage Project

The Colorado River system - unique in terms of its storage capacity - can store more than 60 million acre-feet of water in Colorado River reservoirs, equivalent to four years of average annual runoff in the basin. This storage provides irrigation supplies for about two million acres of land while serving more than 23 million people.