Southwest's Water Future Dim

Scientists and water experts foresee a challenging future for the U.S. Southwest, which is likely to see dwindling water supplies as the climate continues changing.

The latest indication of trouble for the region came today with the publication of a study that says Lake Mead has a 50 percent chance of going dry by 2021. Lake Mead is part of the Colorado River system, which supplies water to Las Vegas, Los Angeles, San Diego and many other communities in the Southwest.

Researchers Tim Barnett, a marine physicist, and David Pierce, a climate scientist, found that current conditions are already causing the river system to see an annual water-flow deficit of nearly 1 million acre-feet, enough to supply almost 8 million people. As climate change worsens and evaporation accelerates, that deficit is likely to go higher, they add.

"Today, we are at or beyond the sustainable limit of the Colorado system," Barnett and Pierce wrote in their study, published in the American Geophysical Union's Water Resources Research journal. "The alternative to reasoned solutions to this coming water crisis is a major societal and economic disruption in the desert southwest; something that will affect each of us living in the region."

Currently, much of the Southwest is already abnormally dry or experiencing moderate to severe drought conditions, according to the National Integrated Drought Information System.

Only some parts can expect even short-term relief, adds the National Oceanic and Atmospheric Administration. Its most recent outlook predicted ongoing drought with some improvement in much of the region, although conditions were expected to persist or worsen in the southernmost parts.

In the long term, scientists foresee an ever-drier future for the region. A study from the Lamont-Doherty Earth Observatory last year, for example, predicted the Southwest could expect its climate to shift to persistent drought, even Dust Bowl-like, conditions in the 21st Century.

"The arid lands of southwestern North America will imminently become even more arid as a result of human-induced climate change just at the time that population growth is increasing demand for water, most of which is still used by agriculture," said Richard Seager, senior research scientist at the observatory and one of the study's lead authors. "The West, and in particular, the United States and Mexico, need to plan for this right now, coming up with new, well-informed and fair deals for allocation of declining water resources."

Many communities in the Southwest are considering, or have already enacted, water-conservation measures such as lawn-sprinkling bans. Some, like San Diego, are even looking at ways to purify treated sewage into drinking water. Ongoing water shortages are also stressing agricultural production in places like California, which supplies much of the U.S. with year-round fruits and vegetables.