Winter snowpack starts strong
High on Mount Rose in early January, Natural Resources Conservation Service hydrologist Jeff Anderson stood in a snowy clearing, holding a hollow metal pole. With both hands, he plunged the pole deep into the snowpack beneath his feet, capturing a cylindrical column of snow. He weighed the sample, repeating the process from four different locations at the site to ensure accuracy. The verdict? The winter is off to a good start.
“Today what we measured was 54 inches of snow depth on the ground, and that snow depth contains 15.9 inches of water content. Right now, for this time of year, that’s 110 percent of normal,” Anderson said.
The snowpack is the year-round water supply for this region.
From January to May, Anderson makes monthly trips to this site—a SNOTEL (snow telemetry) station at Mt. Rose ski area—one of the NRCS’s network of more than 800 SNOTEL stations in the Western U.S. Though SNOTEL data collection is automated and sent out hourly via radio signal, Anderson takes on-the-ground measurements that are used to verify the accuracy of the sensors, using a method that was developed on Mt. Rose more than 100 years ago. “This is where snow surveying really began—up on Mt. Rose,” said Anderson.
The history of snow surveying in the Western U.S. has close ties to our region. During the early 1900s, Dr. James Church, a professor of classics at the University of Nevada, Reno, took an interest in the science of snow. Recognizing the important connection between snowpack and the water level in Lake Tahoe, he developed a tool called the Mt. Rose sampler to measure how much water the snow contained. Using this information, water managers could predict the amount that the lake level was likely to rise each spring.
From 1905 to 1912, Church established snowpack measurement points along snow courses at Mt. Rose and Lake Tahoe. Two of these sites have data that go back as far as 1913, providing some of the longest running snowpack datasets in the country.
“There are quite a few courses in the Tahoe and Truckee region [with data] that go back over 100 years, with measurements that he started,” Anderson said. “It’s quite a data legacy. Our area is fortunate to have that.”
Church’s methods spread across the West and were adopted by the Federal-States Co-Operative Snow Survey in 1935, a program that evolved into NRCS’s present-day snow survey. Today, Anderson and other snow surveyors carry on the modern rendition of Church’s work.
The hollow snow tube that Anderson uses to measure snowpack—the Federal snow sampler—is an updated version of Church’s original Mt. Rose sampler. Though automated SNOTEL stations have largely replaced the need for manual snow measurements, Church’s historical snow courses are still visited and measured once per year, on April 1.
At SNOTEL stations, snowpack weight is now measured using an oversized scale called a snow pillow. Since the water content in an inch of light, fluffy powder snow can vary greatly from that of an inch of wet, slushy snow, snowpack weight is considered a more accurate measurement of water content than snow depth. “Water weighs the same whether it’s a liquid or a solid. That’s really what we’re really interested in—how much water is in the snow,” Anderson said.
This water, as Church realized long ago, is what will refill our lakes and reservoirs in coming months.