Arizona, Nevada and Mexico will be required to take less water from the Colorado River for the first time next year under a set of agreements that aim to keep enough water in Lake Mead to reduce the risk of a crash.
The federal Bureau of Reclamation activated the mandatory reductions in water deliveries on Thursday when it released projections showing that as of Jan. 1, the level of Lake Mead will sit just below a threshold that triggers the cuts.
Arizona and Nevada agreed to leave a portion of their water allotments in the reservoir under a landmark deal with California called the Lower Basin Drought Contingency Plan, which the states’ representatives signed at Hoover Dam in May.
California agreed to contribute water at a lower trigger point if the reservoir continues to fall. And Mexico agreed under a separate accord to start contributing to help prop up Lake Mead, which is now 39 percent full.
The Colorado River’s reservoirs have dropped dramatically since 2000 during one of the most extreme droughts in centuries. Farms and cities across the Southwest have long been taking more from the river than what flows into it, and climate change is adding to the strains by pushing up temperatures.
Reservoirs were approaching levels last year that would have triggered a shortage and required deeper cuts, but heavy snow across much of the Rocky Mountains this winter boosted runoff and raised reservoir levels. The river’s reservoirs are now at 55% of total capacity, up from 49% at the same time last year.
But Lake Mead is still projected to be just below the threshold of 1,090 feet above sea level at the beginning of next year. That will put the reservoir in a zone called “Tier Zero,” at which the first cuts take effect.
The Desert Princess, a three-level paddle-wheeler, cruises past Rock Island, March 17, 2019, in the Lake Mead National Recreation Area near the Arizona/Nevada border. A high-water mark or “bathtub ring” is visible on the island; Lake Mead is down 139 vertical feet. (Photo: Mark Henle/The Republic)
“While we appreciate this year’s above-average snowpack, one good year doesn’t mean the drought is over. We must remain vigilant,” federal Reclamation Commissioner Brenda Burman said in a statement. She applauded the seven states that depend on the river for coming together to finish the set of drought-contingency plans. Burman said the actions laid out under those agreements “will help ensure the reliability of the Colorado River system for the 40 million people dependent upon it.”
Arizona will see a cut of 192,000 acre-feet in water deliveries next year, or 6.9% of its total allotment of 2.8 million acre-feet. Nevada’s share will be reduced by 8,000 acre-feet, while Mexico’s will take 41,000 acre-feet less. That water will remain in Lake Mead, and will only be recovered once the reservoir rises above an elevation of 1,100 feet.
The cuts under the Drought Contingency Plan, or DCP, represent 12% of the total water supply for the Central Arizona Project, which delivers water by canal to Phoenix, Tucson and other areas. Chuck Cullom, manager of Colorado River programs for CAP, said this reduction will mean “eliminating the water that would have been available for underground storage, banking and replenishment,” and cutting CAP deliveries to agriculture by about 15%.
That reduction, while significant, is about the same as what CAP has been leaving voluntarily in Lake Mead since 2015 through conservation efforts, Cullom wrote in a blog post. “In essence, CAP and its water users have been planning and preparing for Tier Zero reductions for the past five years. The difference is that those previous contributions were voluntary — now, under DCP, these contributions are mandatory.”
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