Arizona uses approximately 7 million acre-feet (maf) of water each year from all sources, about 2.8 maf of which comes fom the Colorado River. Of our Colorado River water, about 1.5 maf moves through a Central Arizona Project (CAP) canal into the metro areas of Phoenix and Tucson. The rest is used along the river, primarily for agriculture in Yuma.
Lake Mead is the reservoir that supplies Arizona’s water from the Colorado River. The region has suffered from a long-term drought, and Lake Mead water levels have declined significantly over the past two decades. The rules governing how water is distributed from the Colorado River focus on Lake Mead water levels. If the projected level falls below 1,075 feet of elevation above sea level, a shortage is declared, and Arizona must cut back its use of water.
The Likelihood of a Water Shortage from the Colorado River is measured by the Bureau of Reclamation, based on annual projections of water levels in Lake Mead.
Data are available only for Lake Mead . Updated every January and August, the August projection of the following January 1 water elevation determines whether a shortage is to be declared on the system.