Water resources specialists from the Natural Resources Conservation Service (NRCS) and cooperating partners are forecasting above normal runoff for March through May in Arizona’s major rivers and streams based on recent snowpack measurements.
In February, runoff was 356 percent of normal on the Salt River and 311 percent of normal on the Verde River.
Statewide, the March 1 snowpack measured 154 percent of the 30-year average, compared with 71 percent a year ago. The Salt River, Verde River, Little Colorado River, and San Francisco-Upper Gila River Basins all have well above normal snow levels for this time of year. The San Francisco Peaks area near Flagstaff is at 188-percent of average as of March 1.
NRCS water resources specialist Dino DeSimone said that as a result of continuing wet conditions in Arizona’s mountain watersheds, the forecast calls for above normal streamflows in all basins during the spring snowmelt season.
“This is turning out to be a banner year for snowpack, total precipitation, and runoff throughout the state,” DeSimone said.
As of March 5 the combined Salt River Project (SRP) system is at 93-percent of capacity with 2,149,427 acre-feet in storage. The SRP system covers the Verde and Salt River watersheds and includes six reservoirs; Horseshoe and Bartlett, both on the Verde River, and Roosevelt, Apache, Canyon, and Saguaro, all on the Salt River. At San Carlos, reservoir storage stands at 362,200 acre-feet, or about 39 percent of capacity.
NRCS takes snow measurements throughout the winter to forecast and track the state’s surface water supplies for the coming year. As a result of these snow measurements, an Arizona Basin Outlook Report is developed and issued every two weeks beginning January 1 through April 1. The report is used by farmers, ranchers, municipal water suppliers, and other water users to help manage limited water supplies.
The snow survey season began January 1, when the NRCS, U.S. Forest Service, National Park Service, and the Navajo Nation began manual measurements of snow depth and snow water content at 38 measurement sites across northern and eastern Arizona.
The same locations are measured each year. The NRCS and its cooperative snow surveyors have been measuring snowpacks and estimating spring runoff in Arizona since 1935.
March 1, 2008 snowpack levels:
Percent (%) of 30-Yr. Average
Watershed Snowpack Levels
Salt River Basin 144%
Verde River Basin 172%
Little Colorado River Basin 144%
San Francisco-Gila River Basin 115%
Other Points of Interest
Chuska Mountains 153%
Central Mogollon Rim 145%
Grand Canyon 138%
San Francisco Peaks 188%
Statewide Snowpack 154%
March 1, 2008 runoff forecast:
Percent (%) of median streamflow
Salt River (near Roosevelt) 120%
Verde River (at Horseshoe Dam) 118%
Gila River (at San Carlos) 158%
Little Colorado River (above Lyman Lake) 175%