It’s that time of the year: Pray for snow in the mountains
December 1, 2010
It’s that time of the year again, when farmers and others tend to keep any eye to the West, checking out the snowfall in the mountains.
It’s those mountains, and that snow, that will provide the majority of water for irrigation, municipal and industrial use in the coming year. While November, December and even January are much too soon to predict next year’s supply, it doesn’t prevent several people from keeping an eye on things.
And one group that starts early with watching is the U.S. Department of Agriculture’s Natural Resources Conservation Service (for you old timers, that used to be the USDA Soil Conservation Service). In northern Colorado that means John Fusaro and Todd Boldt with the Fort Collins NRCS office.
Fusaro provided some interesting background on the job his agency is involved with each snow year.
He noted that the stage is set for the snow-water year even before the first snowflakes start to fall in the high country. The amount of moisture that accumulates in the soil early in winter, before the snowpack has a chance to develop, will affect runoff from snowmelt the following spring.
Dry soils will absorb more of the snowmelt than wet soils, and how much is absorbed depends on soil characteristics as well as the amount of precipitation. Wind, air temperature, storm frequency and the amount of moisture in the atmosphere all play a part in determining the snowpack and the water content of that snowpack.
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Once the snow starts falling, the work of monitoring the snowpack as it builds begins.
The USDA has conducted a cooperative snow survey program since 1935, which is a little longer than Fusaro and Boldt have been around. The program is a federal, state and local partnership directed by NRCS and includes not only Colorado, but Arizona, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming as well. Alaska and southern Canada are also partners. California has an independent program.
The program, under federal leadership, was developed following the drought of 1934, when ag leaders requested USDA’s help in forecasting water supplies for the 1935 growing season.
Since then, about 1,600 snow courses have been developed. Generally, they are about 1,000 feet long and are located in small meadows protected from the wind. NRCS specialists, such as Fusaro and Boldt, take measurements near the first of the month during the snowpack season. In the Poudre Canyon, there are four such courses, and in the Big Thompson Canyon, there are four more.
In 1977, the NRCS began development of a network of automated radio telemetry sites for collecting snow survey data. The so-called SNOTEL network provides the agency’s offices with daily or more frequent information on streamflow potential. That comes in handy especially during periods of flood or drought. There are half a dozen or more SNOTEL sites in Larimer County and several more in northern Colorado.
The manual snow courses are marked with bright yellow signs, and a problem every year has to do with snowmobilers and hikers who don’t pay attention to those markers. By driving or hiking across them, the snow becomes packed, which hampers readings, which does not make Fusaro and Boldt happy campers.
Manual surveys require a two-person team who measure snow depth and water content at designated locations on a snow course. The team uses an aluminum tube and a weighing scale at regular intervals along the course. From the weight and depth of the snow, calculations can be made to determine density and the amount of water contained in the snowpack. An average of all samples taken is calculated and used to represent the snow course.
Those monthly measurements give water users a good idea of the amount of water that will be available for the coming year.
In short, pray for snow.
Bill Jackson has covered agriculture for The Tribune for more than 30 years. To reach him, call (970) 392-4442.