Posted: Friday, February 05, 2010
But, right now, the forecast for the spring snow melt runoff is only about average for the Rio Grande, Pecos and Canadian river basins, according to Wayne Sleep, an NRCS hydrologic technician. The problem is the snowpack isn’t great in the southern Colorado mountains that also feed the rivers.
Good snowpack translates into good spring water runoff into the state’s rivers and reservoirs, if a few things don’t happen between now and April.
If the snowstorms don’t disappear.
If spring winds don’t blow too hard and hot.
And if spring rains don’t melt the snowpack too quickly.
After a dry November and December, New Mexico’s mountains were favored by El Niño with several snow-heavy storms through January and in the first week of February. Cold temperatures have helped keep the snowpack in place.
“The ongoing snowfall and weather in February and March will be important factors affecting water supplies for the remainder of the year,” Sleep said. “If we can stay in the storm track and keep picking up snow, this has the potential to be a great runoff.”
Snow survey specialists, like Sleep, rate the “good” of a snowpack based on its water content. A few inches of snow on the ground usually equals less water when melted down. So the more snow, and the “wetter” it is when it piles up, the better for the state’s water supplies come spring.
“Approximately 60 percent of our New Mexico water supply comes from snowmelt,” Sleep said.
The snow-water equivalent of the snowpack in the Sangre de Cristo Mountains currently ranges from 99 percent to 116 percent of the normal amount averaged from 1971 to 2000. The snowpack feeds river flows in the Rio Grande, Pecos and Canadian rivers. Total precipitation in the Rio Grande and Pecos basins was about 130 percent of average for January.
The snowpack feeding the Rio Chama and Jemez rivers both have water content above 100 percent of the norm.
The snowpack water content in the Gila range is from 182 to 246 percent of the norm, spelling a potentially great season for the San Francisco, Gila and Mimbres rivers in southwestern New Mexico. “This is probably their best year in 15 years,” Sleep said.
Sleep said the snowpack is also better than usual at lower elevations — from 6,000 to 9,000 feet — in Northern New Mexico. The Estancia Valley and the Pecos Valley picked up 6 to 9 inches of snow in the last storm Feb. 3 and several inches in the storm the week prior.
The snowpack assessment is gathered by Sleep and a team of NRCS snow surveyors who monitor more than 50 high-elevation sites in remote parts of the New Mexico mountains. The sites automatically collect and send telemetric data hourly on precipitation, snow depth and temperature to NRCS computers. The snow surveyors take periodic back country hikes and snowmobile rides to manually gather data.
Other NRCS teams gather the same data at sites across the West.
The spring runoff usually starts in late March or early April.
