Arizona Snowpack Levels Below Average

Runoff predicted to be less than half of normal

PHOENIX, March 8, 2011—The Arizona Basin Outlook Report released this week by USDA’s Natural Resources Conservation Service (NRCS) shows the state snowpack to be at below average levels. The federal agency monitors snow conditions in Arizona’s mountain watersheds each winter to estimate the amount of water available for spring and summer uses.

“Precipitation in the mountains of northern and eastern Arizona has been well below average since the beginning of the year, except within the Verde River Basin,” said Dino DeSimone, state water supply specialist with the NRCS in Phoenix, Arizona. “True to form for a La Nina year, this dry trend is expected to continue. As a result, spring runoff is expected to be at near record low levels,” DeSimone said.

Among the findings in the Basin Outlook Report, the Salt River basin snowpack was measured at 58 percent of the 30-year average; the Verde River basin at 94 percent of average; and the San Francisco-Upper Gila basin at 48 percent of average. The southern headwaters of the Little Colorado River basin had 66 percent of average snowpack, while the central Mogollon Rim was at 73 percent of average. In the Chuska Mountains of northeastern Arizona, snowpack conditions were measured at 88 percent of average.

The current streamflow forecast calls for well below normal runoff over the March-May forecast period. Flows over these three months, typically the time of year when the greatest runoff occurs from snowmelt, is expected to be only 18 percent of median on the Little Colorado River; 22 percent on the Salt River; 42 percent on the Verde River; and 23 percent on the Gila River. The Colorado River inflow to Lake Powell, however, is estimated at 116 percent of average for the forecast period April-July.

As of March 1the six Salt River Project reservoirs held a combined total of 2,022,200 acre-feet (acre-feet) in storage at 87 percent of system capacity. San Carlos reservoir held 113,600 acre-feet storage, which is 13 percent of capacity. Storage in Lyman Lake was 18,000 acre-feet. The combined storage of Lake Mead and Powell on the Colorado River was 2,352,000 acre-feet, which is 48 percent of combined capacity. An acre foot of water equals 325,851 gallons and is enough to supply a family of five for a year.

The NRCS Arizona Basin Outlook Report and other related reports are available on the Internet at http://www.az.nrcs.usda.gov/snow. For more information, call NRCS Water Resources Specialist, Dino DeSimone, at 602-280-8786.