ABSTRACT
Arizona is an area of geographical complexity, from Sonoran desert to alpine meadows; its water resources are equally complex. Desert rivers are flashy and unpredictable and nearly every major river in the state has been dammed for water storage. The Colorado River, the large, workmanlike river that serves 7 different states and the country of Mexico, was over-allocated from the first legal compact in 1922, yet has remained a surprisingly stable source of supply, despite significant increases in demand, due to the large water storage dams constructed at Boulder Canyon and Glen Canyon. The Basin and Range Physiographic Province that covers the lower half of Arizona contains few perennial streams, but large aquifers. This combination of surface water and groundwater supplies has enabled Arizona to grow in substantial ways. Additionally, Arizona has been successful in avoiding large scale water crises caused by drought and uncertain supplies through innovative water resource management policies. In 2012, Arizona’s population hovers around 6.5 million people, primarily located in a “megapolitan” known as the Sun Valley corridor that stretches from south of Tucson to north of Phoenix, a distance of more than 200 miles. They use, on average, 6.9 million acrefeet (MAF) of water annually for agriculture, residential, commercial and industrial purposes. Arizona’s water supply is comprised of renewable water supplies such as surface water from the Colorado River and in-state rivers (3.71 MAF) and reclaimed wastewater (0.21 MAF); and non-renewable groundwater (2.99 MAF). Agricultural uses continue to require the vast majority of Arizona’s water supplies at 4.7 MAF, with municipal uses at 1.5 MAF and industrial uses at 0.50 MAF.73
