Central Arizona Project (CAP)
The Central Arizona Project (CAP) is a major water management initiative in the United States, established on September 30, 1968, and largely completed by 1993. This extensive system of pumping plants, dams, aqueducts, and pipelines spans over 540 kilometers, facilitating the transfer of water from Lake Havasu, a key source fed by the Colorado River. The CAP has been crucial in supporting agriculture across Maricopa, Pima, and other counties in Arizona, while also enabling the growth of urban centers like Phoenix and Tucson. However, this project has raised environmental concerns, notably harming various fish and wildlife species downstream. Originally conceived to promote sustainable agricultural practices, the project has shifted focus over time, reallocating water from agricultural to municipal and industrial uses due to changing economic demands. The CAP also generates hydroelectric power, contributing to local energy needs. While it has played a pivotal role in addressing water scarcity in the region, the environmental impacts and historical context highlight the complexities and challenges of water management in the Southwest.
Subject Terms
Central Arizona Project (CAP)
- DATE: Established September 30, 1968; substantially completed 1993
The Central Arizona Project (CAP), a series of pumping plants, dams, aqueducts, and pipelines stretching more than 540 kilometers, is the largest water transfer project in the United States. Drawing water from Lake Havasu has supported agriculture in southwest Arizona and made possible the growth of major cities, while harming several species of fish and animals downstream.
Background
As the area that makes up the southwestern United States was settled and populated by Europeans in the nineteenth century, the need for more water became apparent. In the early 1900s, the Southwest looked to the Colorado River basin as a source of water, and a series of laws and court decisions called the “Law of the River” were established to ensure that each state was treated equitably. Decades of court cases attempted to determine the amount of the water to which Arizona was entitled. Through the 1950s Arizona lobbied for authorization of a Central Arizona Project, and the US secretary of the interior called for a comprehensive Colorado River plan to address the future water needs of seventeen Western states. Passed on September 30, 1968, Public Law 90-537, 82 Stat. 885 created the Colorado River Basin Project and the Lower Colorado River Basin Development Fund, which authorized in turn the development of the Dixie Project in Utah and the Central Arizona Project in Arizona and New Mexico.
Provisions
The Central Arizona Project was designed to move 4,000 square kilometers of water from Lake Havasu, fed by the Colorado River, to agricultural lands in Maricopa, Pima, and Pinel Counties in Arizona, and to Catron, Grant, and Hidalgo Counties in New Mexico. Because of high costs and lower-than-expected demand, however, the New Mexico portion of the project was never built. During the years of construction, the economy of Arizona began to shift from agriculture to industry, and the metropolitan areas of Phoenix, Scottsdale, and Tucson experienced rapid growth. As a result, CAP waters were reallocated, so that over time more water would be designated for municipal and industrial use and less for agriculture.
Impact on Resource Use
The purpose of CAP, as it was conceived in the late 1940s, was to keep agriculture thriving without depleting supplies. By most accounts, this goal was not realized. In addition, the diversion of water from its natural course has created environmental problems downstream from Lake Havasu, including the extinction of fish and wildlife, in spite of several successful efforts along the project itself. Dams along the project provide hydroelectric power, reducing the region’s dependence on other forms of power generation.
Bibliography
"History of CAP." Central Arizona Project, https://www.cap-az.com/about/history-of-cap/. Accessed 26 Dec. 2024.
"The Storied History of the Central Arizona Project." Civil Engineering Source, American Society of Civil Engineers, 1 Mar. 2022, www.asce.org/publications-and-news/civil-engineering-source/civil-engineering-magazine/issues/magazine-issue/article/2022/03/the-storied-history-of-the-central-arizona-project. Accessed 26 Dec. 2024.