Drought-Parched Lake Mead Could Leave Seven States High and Dry

Historic-low water levels in the Colorado River Basin's biggest lake spells trouble, and potential water restrictions, throughout the West.

Lake Mead, the nation's largest reservoir, reached historic low levels over the weekend, another indication of the persistent drought that grips the American West.

Saturday night, even after a prolonged rainstorm, the gauges at Lake Mead settled out at 1,080.13 feet.  It's the lowest recorded lake elevation since the reservoir was filled in the 1930s, said Rose Davis, a spokeswoman for the Bureau of Reclamation, a federal agency that oversees water resources.

And it didn't stop there.  By mid-afternoon Tuesday, the lake was at 1,079.76 feet.  If lake levels fall below 1,075 feet––which could happen this summer––it will trigger restrictions on the amount of water than can be drawn from the lake.  Additional restrictions would follow if levels reach below 1,050 feet and 1,025 feet.

The city of Las Vegas, which gets 90 percent of its water from Lake Mead, is so concerned about falling reservoir levels that it is building a new intake pipeline deeper within the lake, to ensure it will be able withdraw water even if lake levels continue to decline.

Lake Mead is part of the Colorado River Basin, which provides a crucial source of water to seven states and Mexico.  The region is in the midst of a 15-year drought, while the state of California is in its fourth consecutive dry year.

The California drought is one of the worst in the state's history, prompting Gov. Jerry Brown to issue unprecedented water use restrictions earlier this month.

Climate change will only exacerbate the impacts, experts say.

Global warming is "more or less a stacking of the deck" that increases the likelihood of dry conditions in the West, said Greg Pederson, a research scientist at the U.S. Geological Survey.

"The way the climate system works out here is it tends to be sticky," Pederson said.  "If it's wet, you get these generally wet conditions for 10 to 20 years at a time, and if it's dry, you typically get dry conditions 10 to 20 years at a time."

While scientists say that climate change may not be the main cause of the drought, it has made it worse.  Global warming has caused the high temperatures that have dried up soils and caused early melting of the snowpack, and many scientists say it has also altered atmospheric circulation patterns that have shifted storms away from the state– meaning much less rain.

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