Water shortages loom in Southwest, could trigger cuts

The Colorado River Basin in December. Water levels in the basin could reach unprecedented lows next year, triggering water delivery cuts to three states.

Water levels in the Colorado River Basin could drop to levels that require cutting water deliveries to California, Arizona and Nevada.

Resource managers in the Colorado River Basin are preparing for an unprecedented scenario: By next year, water in Lake Powell is likely to drop to a level that will trigger mandatory cuts in water deliveries to California, Arizona and Nevada.

The U.S. Bureau of Reclamation  will release a 24-month projection for Lake Powell storage levels in early August. Those numbers will help determine whether cutbacks kick in, but some water managers in the basin are already preparing for the worst.

About 36 million people in seven states and 20 Native American nations rely on Colorado River water, which is collected in reservoirs like Lake Powell. In addition, diversions from the river irrigate 4 million acres of land, producing about 15 percent of the nation's crops.

Related: Weapons giant attacks world's drinking water shortages

If farmers in Arizona and Southern California have to find more expensive replacement water, it would affect food prices across the country.

The last two years rank among the driest on record in the Colorado River Basin. Flows into Lake Powell, which is on the border of Arizona and Utah, have only been about one-third of average.

"Frankly, I don't think most people thought this would happen so soon," said Colorado River expert Doug Kenney, director of the Natural Resources Law Center at the University of Colorado Boulder. "But it's destiny. If you use more water than what's coming into the system, there will be shortages, and the shortages will be felt."

Kenney told MSN News that the impending shortages highlight how important it is to have built-in mechanisms for responding to such a situation, rather than letting it develop into a legal battle among affected states.

Conservation groups say the concern about Colorado River water supplies is one of the first manifestations of climate change in the Southwest. Some scientists are a bit more cautious, pointing to long-term historical variations in Colorado River flows in the pre-greenhouse gas era.

Even with a return to average precipitation and river flows, water levels in Lake Powell could affect power generation over the next few years, leading to higher electricity prices, according to Eric Kuhn, director of the Colorado River Water Conservation District.

Related: Five states running out of water

If water levels in the basin drop to the trigger level, water deliveries to California, Arizona and Nevada would be cut by 750,000 acre-feet — about 244,500,000,000 gallons of water. An acre-foot of water is about 325,853 gallons, equal to the average annual household use in the U.S.

The cuts are mandated by a 2007 agreement that anticipated water shortages in the Colorado River.

"The bottom line is, the 2007 guidelines were major progress — people could agree on reservoir levels where things are out of the normal, and we've hit that," Kuhn told MSN News. With the overall climate picture shading toward drier conditions, water managers need to be very cautious in planning for the next few years and beyond, he added.

In a July 1 memo that outlines what the looming shortages could mean for the region, Kuhn wrote that several more dry years would lead to even greater cuts in water deliveries to the arid Southwest. He said there also would be huge impacts to hydropower generation at the Hoover Dam, on the border of Arizona and Nevada.

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