Colorado River Management Section

Overview - Water Supply and Availablity

Of the 7.5 million acre-feet of water available to the Lower Basin states of California, Arizona and Nevada, Arizona’s Priority 4 (post 1968) contractors, including the Central Arizona Project, have a junior priority. If water supplies are below normal, water deliveries to Arizona’s Priority 4 contractors will be reduced by the Secretary of the Interior, in an amount that depends upon the overall reduced water storage in Lake Mead.  The Central Arizona Project is expected to take a large portion of the reductions, which are expected to total between 400,000 and 600,000 acre-feet, and possibly more. 

When the Colorado River Compact was negotiated, average annual flows were estimated to be about 18 million acre-feet. Today a more accurate flow estimate is about 16.3 million acre-feet, however total Colorado River allocations, including the Mexican Treaty obligation, total 16.5 million acre-feet. Annual flows are highly variable ranging from a low of 6.3 million acre-feet to a high of 27 million acre-feet.  Concern over possible long-term water supply shortages has resulted in studies regarding water supply augmentation of the Colorado River by increasing system delivery and operational efficiencies, importation, weather modification, and vegetation management.  Other methods of augmentation such as desalinization of seawater or brackish water continue to be evaluated, but these methods have relatively high costs making them less feasible.

 

<< Back to the main Colorado River Management Section.