Managing Semi-Arid Watersheds: Watershed Basics - Water Systems in Arizona

Much of Arizona's water supply is delivered to its residents via rivers and dams or reservoirs. The largest water system in Arizona is the Central Arizona Project. The Central Arizona Project is a 336 mile long, concrete lined, canal system that brings water from the Colorado River, at Lake Havasu, to the state's major metropolitan areas of Phoenix, Casa Grande, and Tucson. As the water travels from Lake Havasu to the end of the aqueduct it will be lifted nearly three thousand feet in elevation by fourteen pumping plants along it's route. This is about a 50 year project that has only recently been completed. The purpose of the Central Arizona Project is to supplement ground water and surface water supplies. The Bureau of Reclamation oversaw the construction of the Central Arizona Project and continues to maintain and operate the system. The Central Arizona Conservation District collects taxes to recoup the cost of construction.

Other water systems in Arizona include large water storage areas such as the man-made lakes found around the state that are the result of an installation of a dam in a river. Arizona has more than 200 lakes, and most of them are man-made. Arizona averages less than 10" of rainfall a year, and most of that rain comes during a relatively short summer season of storm events. Therefore, it is necessary to collect and store that water in order to provide a year round supply. The Colorado River has Lake Mead, above Boulder Dam, and Lake Powell, above Glen Canyon Dam, which are the two largest lakes in Arizona. Another benefit of water storage systems is that they can provide a source of hydro-electric power and water recreation areas.

Smaller canal or open ditch systems are used in rural areas to divert water from many of Arizona's major waterways to provide irrigation water for agricultural use. Other than metropolitan use, Arizona's primary water using industry is irrigated agriculture.

Water rights are established by historical use, court decisions, adjudications, and/or the state water department.