A projected 9 percent drop in Colorado River flows could trigger a shortage that would limit the amount of water Arizona receives, according to the U.S. Bureau of Reclamation.
Last week, the Bureau released a 24-month estimate on its Colorado River reservoirs, which supply water to seven states, including Arizona.
The study projects a 9 percent decline in flows into Lake Powell in the period between October 2014 and September 2015. The projection calls for inflows of 7.48 acre-feet instead of 8.23.
The news set waves of alarm outward throughout the region, with the threat of the first-ever cut in deliveries to the Lower Basin, where 25 million people rely on Colorado River water.
The projections once again underscore the importance to Rim Country of the Blue Ridge pipeline, which will double Payson’s water supply. The Colorado River shortage will likely spur increasing competition among Arizona cities and towns to secure a water supply for future growth.
Meanwhile, the Salt River Project’s daily water report this week noted the monsoon-related rise in water levels on the Salt and Verde rivers, as the Valley nears the end of the peak water use period. The Salt River reservoirs have recovered to 55 percent full while the Verde River reservoirs remain at about 62 percent full.
The Salt River is running at about 93 percent of normal where it enters Roosevelt. The Verde River is running at 82 percent of normal.
If the Bureau of Reclamation predictions prove accurate, the already-half-empty Lake Mead could fall below the 1,075-foot elevation, which would prompt the declaration of a water shortage for the Lower Basin states, which includes Arizona, Nevada and California.
Such a declaration would cut Central Arizona Project deliveries by 230,000 acre-feet — a roughly 20 percent reduction. Most of the CAP water goes to Phoenix and Tucson.
This reduction would impact lower priority CAP users, including underground storage by the Arizona Water Banking Authority and Central Arizona Groundwater Replenishment District, as well as non-Indian agriculture.
“While the possibility of a shortage declaration is significant, Arizona has been planning and preparing for just such a condition for decades,” said Sandra Fabritz Whitney, director of the Arizona Department of Water Resources and chairman of the Arizona Water Banking Authority. “Arizona has led the nation in conservation efforts and long-term water management, including storing millions of acre-feet of water underground as a backup supply.”
David Modeer, general manager of the CAP, added that, “While all of us in Arizona should continue our conservation efforts, this also serves as a call to the federal government and all Colorado River water users that we need to work together to seek creative management solutions in the short term and augmentation of supplies in the long term.”