After back-to-back driest years in a century on the Colorado River, federal water managers are giving Arizona and Nevada a 50-50 chance of having water deliveries cut in 2016.
A U.S. Bureau of Reclamation operations plan made public Friday will for the first time slow the flow of water from the Lake Powell reservoir upstream of the Grand Canyon to the huge Lake Mead reservoir that provides almost all of Las Vegas' water.
But a bureau official said Lake Mead won't reach a low point next year that would trigger cuts to Sin City's main drinking water supply.
"What we've seen in the last two years are the worst consecutive years of inflow in the last 100 years," bureau Lower Colorado Regional Director Terry Fulp told The Associated Press.
"We're going to slow Powell's decline. That will hasten Mead's decline," he said. "But next year, we can adjust again."
The bureau that controls the levers at the Glen Canyon and Hoover dams said cities, states, farmers and Indian tribes will get their full Colorado River water deliveries next year - and probably in 2015.
Fulp said a 2 percent chance of the Lake Mead level dropping in 2015 to the trigger point for a shortage declaration increases to 50 percent in 2016.
Bureau officials and environmentalists have been raising alarms in recent months about demand outstripping supply on the river serving some 40 million people in seven states and cities including Los Angeles, Phoenix, Denver and Las Vegas.
"The problem isn't drought, and a big rain storm or a heavy winter snow season won't fix this," said Bob Irvin, president of American Rivers in Washington. D.C. The advocacy group in April labeled the Colorado River the most endangered waterway in the U.S.
"What we need are fundamental changes in how we manage water in the Colorado basin," Irvin said. "This is the loudest wake-up call so far."
Fulp pointed to a federal report issued in December that concluded that the river may not meet the needs of a growing regional population by 2060.
"The study showed very clearly that demand and supply curves are crossing and demand is exceeding supply," he said.
Fulp compares managing the two largest reservoirs on the Colorado River to pouring tea from one cup to another. He said the usual annual delivery of 8.23 million acre-feet of water from Lake Powell to Lake Mead will be cut next year about 9 percent, to 7.48 million acre-feet. Officials say one acre-foot is enough to serve two Nevada families for a year.
Lake Powell, near the Utah-Arizona state line, would decrease from 45 percent this year to 42 percent next year.
Lake Mead, on the Nevada-Arizona state line, is currently at 47 percent capacity and could drop to 39 percent capacity next year.
Lake Mead on Friday was at 1,106 feet. The low level next year would be about 10 feet above a 1,075-foot elevation trigger point agreed upon in 2007 by the seven U.S. states that share river water under a 1928 allocation agreement. Native American tribes and Mexico also get shares of Colorado River water.
A shortage declaration would mean Arizona would get 11.4 percent less than its 2.8 million acre-foot allocation. Nevada would get 4.3 percent less than its 300,000 acre-foot allotment - a loss equivalent of the amount serving 26,000 homes.
Southern Nevada Water Authority chief Pat Mulroy last week floated the idea of a federal disaster declaration due to drought in the Southwest. Meanwhile, local officials stress conservation, and note that iconic dancing fountains on the Las Vegas Strip use recycled water.
Mulroy called Friday's projections "an unwelcome development that will demand all the resolve and ingenuity we can muster."
Reaching the shortage declaration trigger point would prompt a vote by southern Nevada elected officials whether to pursue plans for a massively expensive and controversial pipeline to tap groundwater in rural counties along the Nevada-Utah state line to slake the thirst of 2 million Las Vegas residents and 40 million tourists a year.
In Arizona, a projected loss of 320,000 acre feet in 2016 wouldn't affect cities like Phoenix, Tucson, and Native American tribes, said Chuck Cullom, Colorado River program manager for the Central Arizona Project.
But the agency would cut the amount of water it stores underground and limit the amount available for purchase by agricultural customers.
California, Colorado, Utah, New Mexico and Wyoming wouldn't see direct cuts in their share of river water in 2016 depending on the Lake Mead water level. But officials acknowledged there would be ripple effects.
"Denver Water has a direct interest in these issues because half our supply comes from the Colorado River," said Jim Lochhead, chief executive of the water agency serving Denver and its suburbs. "Issues like compact curtailment or political or legal confrontation along the river will affect that supply."
Southern California gets 25 percent of its water from the Colorado River and 30 percent from drought-stricken in-state sources, said Jeff Kightlinger, Metropolitan Water District of Southern California general manager. The agency serves 19 million customers.
Both sources are threatened by drought, which is evident throughout the region.
"It's serious," Kightlinger said Friday. "The important thing is how well the basin states are working together. We all recognize the immediate impact on southern Nevada. We're not running to the courthouse. We're working together to deal with this."
In Coolidge, Ariz., Hohokam Irrigation District manager Sidney Smith said she's been advising farmers to make sure their wells are working in case they lose Colorado River water and have to revert to pumping groundwater.
"Basically if farming stops here, it's going to hurt the whole community," Smith said.
Steve Erickson of the Great Basin Water Network in Salt Lake City, raised the specter of a "panic reaction" and free-for-all to dam and divert water before it reaches lakes Powell and Mead.
"That's always been the Western way - use it or lose it," Erickson said. "Everybody building water diversions - that's old thinking."
Utah Division of Water Resources chief Dennis Strong said his state doesn't currently draw its full 1.4-million acre-foot allotment of river water. He said his concern was for states in the Colorado River's lower basin.
"We've spent 14 years in a drought situation - with only three above-average years - and Lake Powell and Lake Mead are below half full," Strong said. "It's hard not to worry about the future when you're below 50 percent."
- By KEN RITTER, Associated Press
Ritter reported from Las Vegas. Foy reported from Salt Lake City. Associated Press writer Felicia Fonseca in Flagstaff, Ariz., contributed to this report.
(© Copyright 2013 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)
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