Since its inception in 1956, the project has grown to include the participation of several related water management projects throughout the river's basin. The projects original scope, and primary focus, are the upper Colorado River itself, the Green River, the San Juan River, and the Gunnison River.
Participating states are Arizona, Utah, New Mexico, Colorado and Wyoming.
Serious consideration for the project began when the Colorado River Compact was signed in 1922 by the participating states, as well as the lower Colorado River states, California and Nevada. As a stipulation of that compact, the upper basin states were required to ensure no less than 7.5 million acre feet per year (293 cubic meters per second) be delivered to the lower basin states. However, the annual flow of the Colorado River at Lee's Ferry in Arizona, the established dividing point, were extremely erratic, ranging from 4 to 22 million acre feet per year. This led to an inability of the upper basin states to meet the minimum delivery requirements to the lower states in dry years, and a loss of significant surpluses in wet years.
In order to regulate the flow of the Colorado and ensure compliance with the compact, a study was undertaken that determined a series of dams and reservoirs on the river and its tributaries would be necessary. A joint effort between the Upper Colorado River Commission, the Bureau of Reclamation and other federal agencies delivered a report with proposed projects to the United States Congress in 1950.
Among the proposed projects was a dam to be constructed on the Green River in Echo Park, in Dinosaur National Monument in Colorado. The proposal created controversy and sparked the ire of Sierra Club director David Brower, who embarked on a national campaign to rescue the park. As part of a compromise, the proposed dam was stricken from the project and replaced with another dam in Glen Canyon, Arizona. Brower, who had not personally visited Glen Canyon prior to the compromise, later lamented the deal, describing it as "the worst mistake of his career" and "'the biggest sin I ever committed'".
A revised, and slightly pared down, version of the plan was passed in to law by Congress in 1956. The legislation called for the construction of dams, reservoirs and related works at Curecanti in Colorado, Flaming Gorge in Wyoming, Navajo in New Mexico and Glen Canyon in Arizona. All but the Navajo project were to include power generation capabilities; the Navajo project was intended as flood control only. Also included in the legislation were several related projects in the Colorado River basin.
As a whole, the system provides a storage capacity of approximately 34 million acre feet (42 billion cubic meters) of water. This capacity is released to meet the Colorado River Compact's delivery requirements during periods of low flow in the system. Additionally, three of the units provide hydroelectric power to major markets in the southwest.
Lee's Ferry in Arizona serves as the southern boundary point for the project, which encompasses the Colorado River upstream from this point and all tributaries.
The Glen Canyon Unit, which consists of the Glen Canyon Dam, Lake Powell and the Glen Canyon Powerplant, is the largest and most important unit of the system. While the dam is located near Page in northern Arizona, the majority of Lake Powell resides in southern Utah. With a total storage capacity of 27 million acre feet (33 billion cubic meters) of water in Lake Powell, the Glen Canyon Unit accounts for over 64% of the systems overall water storage capacity. The 1,304,000 kilowatt capacity of the dam's hydroelectric generators accounts for almost 75% of the overall generating capacity of the project.
In spite of its importance to the system, the Glen Canyon Unit has also been the source of controversy even before it began operating in 1964. Sierra Club director David Brower, who was partially responsible for the location of the dam as part of a compromise, later regretted the decision. Former Arizona Senator Barry Goldwater, who was a proponent of the dam in the beginning, later recanted his opinion and admitted that he, too, had regretted supporting the project. Recent calls for the draining of Lake Powell and the restoration of Glen Canyon by environmental groups such as Sierra Club have resulted in the founding of several advocacy groups for the cause such as Living Rivers and Friends of Glen Canyon, as well as opposition groups such as Friends of Lake Powell. Given the importance of the unit to the project as well as its impact as a tourist destination to the region, restoration efforts face significant opposition and there currently exist no plans to cease operations at Glen Canyon.
Not directly a part of the project but built as a direct result of it, the Glen Canyon Bridge was constructed over the river in 1959. At the time of its completion it was the highest arch bridge in the world. It currently serves as one of only two bridges to cross the Colorado River between Lake Mead and Lake Powell, carrying the majority of the traffic between northern Arizona and southern Utah.
The Flaming Gorge Unit consists of the Flaming Gorge Dam and the Flaming Gorge Reservoir, and the dam's powerplant. The dam impounds the Green River near Green River, Wyoming. Portions of the reservoir spill over into northeastern Utah.
Completed in 1964, the dam provides water storage and hydroelectric generation, as well as flood control on the Green River, the primary tributary to the Colorado. The powerplant in the dam has a capacity of 86,000 kilowatts, or about 8.5% of the entire system.
The dam was completed in 1963, and was actually the first of the units in the project to be completed. Unlike the subsequent dams, Navajo Dam does not have any power generating capacity.
The Aspinall Unit was originally named the Curecanti Unit, but was renamed for former congressman Wayne N. Aspinall in 1980. Aspinall had been a strong proponent of water reclamation projects in Colorado and the western US in general, and was seen as a key opponent to David Brower in the fight to enact the Colorado River Storage Project. Brower was known to have fought regularly with Aspinall, going so far as to state that he had seen "dream after dream dashed on the stony continents of Wayne Aspinall.
As a whole, the Aspinall Unit has a generating capacity of about 290 kilowatts, or about 17% of the entire Colorado River Storage Project, making it the second most productive unit after Glen Canyon.
The Morrow Point Dam impounds the Gunnison River downstream from the Blue Mesa Dam but upstream of the Crystal Dam, putting it in the center of the Aspinall Unit. Completed in 1968, Morrow Point is the largest and most productive of the Aspinall dams. Morrow Point has a generating capacity of 173,334 kilowatts, making it the second most productive dam in the entire Colorado River Storage Project system. It provides about 60% of the Aspinall Unit's generating capacity.
Additionally, the Morrow Point Dam is the first thin-arch concrete dam to be build in the Colorado River Storage Project system.
Crystal Dam has the smallest capacity of the hydroelectric dams in the system, providing some 31,500 kilowatts capacity, or just over 1% of the Aspinall Unit's capacity.
11 projects were included as participating projects in the 1956 legislation. These projects include:
Wyoming's Eden Project was authorized independently in 1949. It was tied to the Colorado River Storage Project by the terms of its own authorization.
An amendment to the legislation in 1962 added two projects to the participants list:
A 1964 amendment added three more projects:
The Colorado River Basin Project Act in 1968 added a final five projects to the participants list:
Four projects, the Fruitland Mesa, Savery-Pot Hook, San Miguel and West Divide Projects, were later found to be infeasible and removed from the list.
The four primary units of the Colorado River Storage Project have a maximum output of 1,813 megawatts of clean hydroelectric power at any given time, comparable to a large coal-fired generating station such as the Navajo Generating Station.
The Blue Mesa and Navajo Dams, built primarily to function for flood control purposes, have saved approximately $10 million in flood-related costs up to the year 1999.
Additionally, the various units of the project have created significant recreational opportunities throughout the otherwise arid southwest regions.