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Lake Mead may go dry by 2021

People will be leaving Las Vegas in droves if Lake Mead runs dry in a few years.

There is a 50 percent chance that Lake Mead, which was created by the Hoover Dam and the Colorado River, will go dry by 2021 because of escalating human demand and climate change, according to a study by Tim Barnett and David Pierce of the Scripps Institution of Oceanography of the University of California at San Diego.

Lake Mead straddles the Arizona-Nevada border, and Lake Powell is on the Arizona-Utah border. Aqueducts carry water from the system to Las Vegas, Los Angeles, San Diego, and other communities in the Southwest.

The old high water line is at the top of the white band. This was taken two weeks ago. Stephen Shankland/CNET Networks

By 2017, there is a 50 percent chance that the reservoir could drop so low that Hoover Dam could no longer produce hydroelectric power. Water conservation and mitigation technologies and policies thus need to be implemented now, the study stated.

The disappearance of the manmade lake would create a tidal wave of ill effects for the southwestern U.S. The lake provides water for large cities like Los Angeles and Las Vegas, as well as for several agricultural interests. The power also keeps on the lights in that region of the country. Imagine Los Angeles on a summer day with sporadic air conditioning and only a trickle of water coming out of the faucet. Then imagine that goes for a week.

"We were stunned at the magnitude of the problem and how fast it was coming at us," Barnett said in a statement. "Make no mistake, this water problem is not a scientific abstraction, but rather one that will impact each and every one of us that live in the Southwest."

"Today, we are at or beyond the sustainable limit of the Colorado system," he added.

The level of the lake has been dropping for years. In the photo below, the white band marks the difference between the old high water level and the current one. It was taken two weeks ago. Barnett and Pierce estimated that there is a 10 percent chance that the lake could go dry as early as 2014. The full report will be published in Water Resources Research, a journal of the American Geophysical Union.

Barnett and Pierce examined annual river flow averages for the past 100 years, evaporation rates, climate predictions, water allocation schedules, past water demand, and future projections, among other factors. Water allocation from the dam has been a political flash point for California, Nevada, and Arizona for years.

And the estimate is conservative, the scientists state. The study goes on the assumption that human-induced climate change factors only began in 2007.

Currently, the Colorado River system, which includes Lake Mead and nearby Lake Powell, is running a deficit of 1 million acre feet of water per year. An acre foot of water is the amount of water that it would take to cover an acre of land with a foot of water. It is enough water for 8 million people.

Other studies have forecast reductions of between 10 percent and 30 percent over the next 30 to 50 years in the Colorado River system. Such a decline could affect the water supply of between 12 million and 36 million people.

Venture capitalists, scientists, and others have said water will likely be one of the first manifestations of problems associated with climate change. China and Australia have already experienced droughts and agricultural problems. Several companies specializing in water management, purification, and desalination have received venture capital investments in recent years. Some companies to keep your eye on include NanoH20 (a desalination company), Vidler Water (a water rights broker) and Altela (artificial rain. No kidding.)

In some places, conservation strategies have been implemented. In Singapore, a small percentage of the country's water comes from the NEWater program, which takes human sewage water and makes it drinkable again. In Las Vegas, the water district offers residents money to remove lawns and replace them with desert landscaping. Still, implementing these technologies has moved slow in most places in the world.

Even if mitigation factors are put in place, the study warned that may not be enough to insulate the Southwest from problems associated with droughts.