LAS VEGAS - December 15, 2009 -A forecasted El Ni?o event predicted to peak early next spring could dramatically increase streamflow and water storage in the Colorado River Basin and bring drought relief to the desert southwest. The findings were reported in a study released today in Eos Transactions, a weekly publication of the American Geophysical Union.

Researchers compared hydrologic data from four historic El Ni?o events with predicted 2009-2010 El Ni?o conditions and found that water storage in Lakes Mead and Powell could increase from nine percent to 48 percent over current levels in the next 24 months, if future conditions prove similar to three of the historic events measured. The current combined water storage of Lakes Mead and Powell is less than 60 percent of capacity, a result of prolonged drought in the desert Southwest.

"Though regions like the desert Southwest will likely experience some drought relief, a single El Ni?o event is not likely to completely replenish the reservoirs that have suffered through near-record drought," said Tom Piechota, co-investigator on the study and director of sustainability and multidisciplinary research at UNLV. "It is still important for both water managers and the community at large to continue aggressive water conservation efforts."

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 2009-2010 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, Nev.

Historic El Ni?o events measured include those from 1972-1973, 1982-1983, 1986-1987 and 2002-2003 - all found to be the most similar to expected 2009-2010 El Ni?o conditions. Of those measured, only the 2002-2003 event showed a streamflow decrease in the Colorado River Basin.

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