El Ni?o weather conditions predicted to peak in early spring could bring much-needed drought relief to the desert Southwest.

Researchers compared data from past El Ni?o events to predict 2009-10 conditions. The current combined water storage of lakes Mead and Powell is less than 60 percent of capacity. Because of El Ni?o, they believe water storage in the two lakes could increase between 9 percent and 48 percent in the next two years.

It's a good sign for the desert Southwest, but not a reason to become lax on water-saving practices, said Tom Piechota, co-investigator on the study and director of sustainability and multidisciplinary research at UNLV. "A single El Ni?o event is not likely to completely replenish the reservoirs that have suffered through near-record drought," he said. "It is still important for both water managers and the community at large to continue aggressive water conservation efforts."

A Climate Phenomenon

El Ni?o is a climate phenomenon that occurs roughly every two to five years and is marked by warming of surface water temperatures in the central and eastern Pacific Ocean. Typically, El Ni?o events result in wetter conditions in many parts of the U.S., including the Southwest, Midwest, and Southeast, and can last for up to 12 months.

Data for both the forecasted and historic El Ni?o events were obtained from the National Oceanic and Atmospheric Administration's Climate Prediction Center. The potential impact of the 2009-10 El Ni?o on Colorado River Basin water supply was determined using a long-term planning model at the Bureau of Reclamation in Boulder City.

Historic El Ni?o events measured include those from 1972-73, 1982-83, 1986-87, and 2002-03 - all found to be the most similar to expected 2009-10 El Ni?o conditions. Of those measured, only the 2002-03 event showed a streamflow decrease in the Colorado River Basin. So, if current El Ni?o conditions mirror the three earlier periods, researchers expect to see an increase in water flowing into lakes Mead and Powell.

Study Participants

The study was reported in Eos Transactions, a weekly publication of the American Geophysical Union. In addition to Piechota, study contributors included:

• Glenn A. Tootle and Oubeidillah Aziz, civil and environmental engineering, University of Tennessee
• W. Paul Miller, UNLV graduate student and hydrologic engineer with the Bureau of Reclamation in Boulder City
• Venkat Lakshmi, earth and ocean sciences, University of South Carolina
• John A. Dracup, civil and environmental engineering, University of California, Berkeley
• Carly Jerla, Bureau of Reclamation