MOUNT ROSE SKI AREA, Nev.—Off to the side of a ski run, a cluster of people in snowshoes watch intently as Jeff Anderson demonstrates a snow survey.
Anderson takes a firm stance and grips a hollow aluminum tube like King Arthur about to put Excalibur back into the stone. He twists the tube into the snow and withdraws it, removing a plug of snow in the process. Then it's the students' turn.
One pupil tries an advanced technique: the "javelin" approach, thrusting the tube into the snowpack with both hands. His sample doesn't match the measured snow depth. Anderson, the Nevada water supply specialist for the U.S. Department of Agriculture's Natural Resources Conservation Service, tells him to try again.
About 55 students—from 12 states, Canada, a Montana tribe, three utilities and the federal government—are here at Lake Tahoe to learn the art of snow surveying. It's a crucial task in the West, where snowpack provides up to 80 percent of the water supply. The Natural Resources Conservation Service funds snow-surveying operations in 12 Western states, including Alaska.
Chad Blanchard, the federal water master who oversees the distribution of water from Lake Tahoe and two area rivers, is here in Tahoe City to see the latest figures.
Blanchard's position as enforcer of water rights in the Tahoe region was created by the court in 1926, after a decade of wrangling over limited supplies. He depends on NRCS data to figure out how much water he needs to release from the lake and several other reservoirs in order to meet supply, streamflow and flood control requirements.
"When you introduce water into the equation, it becomes very, very prone to disputes and arguments," Blanchard said. "Neighbors that were friends at one time end up hating each other."
Local irrigation districts depend on the forecasts to tell farmers how much water to expect for their crops.
Measuring an ugly problem
"This time of year, I start getting lots of calls from our users in the project," said Walt Winder, deputy district manager of the Truckee-Carson Irrigation District, which serves about 2,500 farmers on 73,000 acres in western and central Nevada—a region that typically receives less than 4 inches of precipitation per year.
"How much water am I going to have available?" Winder said. "Do I have enough to do rotation? What am I going to and not going to be able to do with the amount of water I have?"
At Lake Tahoe, the birthplace of snow surveying, results are paltry in mid-January, which is typically the snowiest month. The area receives 190 inches of snow per year, on average—46 inches of it by January. The snow surveyors at Mount Rose turn up just 22 inches.
"Tahoe City is a very good indicator of the basin," Blanchard said. "It's a very good indicator of overall precipitation and moisture health of the basin.
"When you get potentially zero precipitation in what should be your biggest month on average, it gets worrisome, obviously."
The snow surveys are decidedly low-tech: A classics professor, James Church of the University of Nevada, Reno, devised the method in 1906 after Lake Tahoe rose to unprecedented levels and residents pressured the local utility to release water down the Truckee River to protect their lakefront property.
The utility needed a way to predict how much water would be entering the lake from the surrounding mountains. Church's method turned out to be accurate within a 10 percent margin. NRCS took over the measurements in the 1930s and has been conducting them, with help from other agencies and private partners, ever since.
Measuring the depth and weight of the snow and doing some basic calculations to determine water content solves the problem of how much water to expect in the spring once the snow begins to melt and make its way down the mountains. Before Church invented snow surveys, water content was measured by taking a sample and melting it.
Since the 1970s, manual surveying has been supplemented by much more advanced techniques, including about 865 fluid-filled steel "pillows" that gauge snow weight and height, as well as satellites that measure the changes in snow thickness from year to year.
But the snow surveyors persist, trekking out to 1,100 manual checkpoints across the West. Some sites are extremely remote, like the one in Wyoming's Bridger-Teton National Forest that can only be reached by a day's ride on horseback.
Anderson and Mike Strobel, the director of NRCS's National Water and Climate Center, coach the students, making sure they avoid common rookie mistakes like discarding the dirt from the end of the tube too close to the sampling site, where it will act as a heat dump, absorbing sunlight faster than the surrounding snow and skewing future measurements.
Poised to break a 1910 record
The students also spend several days undergoing outdoor survival training. While training normally involves learning to build a snow cave and spending the night in it, the lack of snow at Tahoe this year meant that they constructed shelters with tarps and trees. Before turning in for the night, they gathered at a bonfire, sipped hot chocolate and told jokes.
Despite the extreme drought now stretching into a fourth year in California, the water experts at Lake Tahoe weren't eager to point the finger at climate change.
Strobel said that evidence of climate change is patchy. "In certain regions and at certain sites, we are seeing changes associated with the changing climate," Strobel said. Some sites are registering more rain rather than snow, and within streams themselves, "we're seeing the peak in the streamflow occurring earlier, indicating the snowmelt is happening at an earlier period."
Blanchard pointed out that although Tahoe City receives an average of 31.3 inches of rain per year, the actual precipitation levels fluctuate wildly. "It's definitely cyclical and varying," he said.
"We don't seem to see the trends," Blanchard said. "We've never really had more than two wet years and an average year in a row."
Even a more subtle measurement, like more precipitation falling as rain instead of snow, isn't apparent, Blanchard said. "We see that for a time, but then it goes back up, snow to rain, so there's not even a significant signal on that data as much as you'd think with the discussions" about climate change, he said.
Still, this year would be a statistical outlier if it turns out to be dry.
"We've never had four years in a row below 90 percent" average precipitation, Blanchard said. "If this year ends up being significantly drier than average, it would be the first since 1910."
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500