Will El Niño feed Lake Mead?

Weather system could raise our water level substantially, but it still won’t dent the drought

If any problem has worried Las Vegans more than the economy it’s been the drought. For 10 years Lake Mead’s volume has decreased, dropping it to a 55-year low and increasing speculation that our metropolis is doomed to run out of water.

But, according to a bold new forecast, hope could be on the horizon. El Niño—that mighty precipitation-producing weather pattern—is expected to gather off the Pacific Coast soon and dump snow on the western Rockies. This potentially prodigious runoff into the Colorado River Basin could increase the water level of Lake Mead up to nearly 50 percent over the next two years.

This conclusion—recently published in the American Geophysical Union’s weekly publication, Eos Transactions—was reached by several national institutions, including UNLV, the Bureau of Reclamation in Boulder City and the University of California, Berkeley. It stated that a surplus of 9 to 48 percent of the current water volume could occur, and that it would be enough to last Nevada from three to 18 years.

However, due to the severity of the drought conditions in Las Vegas—once a desert oasis replete with artesian springs—the higher levels in Lake Mead don’t guarantee more water for Las Vegas.

And even with El Niño contributing about two inches of rain in January, a total that topped the amount of precipitation received in the Las Vegas Valley for all of 2009, the long-term forecast is no different.

“If the broader Colorado River Basin has a larger water supply in a particular year, that can create situations where they have surplus for states,” says Tom Piechota, director of UNLV’s Sustainability and Multidisciplinary Research Office and co-author of the study. “But I doubt if a declaration of surplus would happen this year. … I think a take-home message is that these El Niño conditions won’t be enough to get us out of a drought.”

Researchers analyzed the amount of precipitation during El Niño years of 1972-73, 1982-83 and 1986-87, when there were similar surface water temperatures in the tropical Pacific Ocean to those predicted for the coming El Niño event. If the current conditions, such as snowpack and temperature, prove similar to past years, water levels will indeed rise, says Paul Miller, hydrologic engineer with the Bureau of Reclamation who helped with the research.

While this forecast is optimistic, some researchers still see the lake as half empty.

“When you’re talking about El Niño, it’s like a short-term variation,” said Tim Barnett, a researcher at the Scripps Institution of Oceanography in San Diego. “What we’re talking about is the long-term evolution of water in the Colorado system—not the ups and downs, not the El Niños— just Mother Nature doing her thing.”

Barnett co-authored a study last February that gave Lake Mead a 50 percent chance of drying up by 2021. Then in April, Barnett and Scripps climate scientist David Pierce analyzed the probability of the Bureau of Reclamation delivering the projected amount of water to the desert Southwest through 2050. “We looked to see if water use in the Colorado system was sustainable into the future,” Barnett says. “And the answer was no.”