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The dusting of snow

Center documents alarming trend in early snowmelt

RED MOUNTAIN PASS – The term “white as snow” is a little misleading in the San Juan Mountains these days.

The snowpack here at 11,060 feet is covered by layers of dust deposited in the last several weeks. These layers have serious ramifications not only for this spring and summer, but also for the future.

Chris Landry and Andrew Temple, accompanied by this curious reporter with the embarrassingly dirty snowshoes, are here to try to give people an idea of what those ramifications may be. They work for an 11-year-old Silverton-based nonprofit called the Center for Snow & Avalanche Studies.

The issue is this: During the last two decades, an increasing amount of dust, mostly blown via storms from northeast Arizona and southeast Utah, has landed on Colorado during the winter and, more often, spring. This dust settles on the snowpack, causing the snow to lose much of its ability to reflect the sun (We’ll talk about “albedo” later) and escalating the rate of melt drastically.

It’s a situation everyone from water managers to river runners, biologists, botanists and climate-change scientists is concerned about. The dust is speeding up the spring snowpack melt by days or weeks. As a result, hydroelectric dams can’t generate power as long. Rafting season ends early. Plants dry up or have shorter pollinating seasons. I wonder about the future of the truly white snowshoe hare that runs across the open meadow.

So Landry and Temple ski regularly into Senator Beck Basin, just north of Red Mountain Pass, to take readings and measurements. I have trudged 10 minutes from the pass on snowshoes and boots that are still dirty from a previous excursion weeks ago. This isn’t a doctor’s operating room, but it is a serious scientific study area. We enter the site on a predetermined path so as not to contaminate it. Landry, the center’s director, doesn’t exactly scold me for the filthy boots, but he’s not eager to have me walking around very far.

Not that the snow isn’t contaminated already. That’s exactly the point: They want to learn just how badly the blown dust has sullied the snow surface. To do this, they measure albedo – the amount of solar radiation an object reflects. An albedo of 1.0 means that 100 percent of the sun’s radiation is reflected. If there were no dust, the albedo of spring snow would be about 0.8, Landry says. Last year, the albedo here reached an extremely low 0.35. At that number, snow can absorb double or triple the amount of solar energy as clean snow; it’s not unusual for melt rates to roughly double at low albedos, Landry says. The center’s 11 sites scattered around the Colorado mountains from Rabbit Ears to Wolf Creek all showed low albedos in 2013.

“That’s a gigantic bonus of energy going into the snowpack,” Landry said. “What we’re measuring across Colorado is severe drops in albedo because of dust.”

There’s a common misconception that snowmelt rate is based on air temperature. But it’s much more related to solar-energy absorption, making albedo a crucial factor, Landry emphasizes.

“The conventional wisdom is hard to overcome,” he said.

Senator Beck Basin is the “sentry” study area, the front line for the Colorado Plateau dust as it blows across Colorado.

We’re at the Swamp Angel site, named for a former mine in the vicinity. It’s the most technologically advanced Center for Snow & Avalanche location, and the only one of its kind in the Colorado River basin. There’s another site in Senator Beck Basin at 12,000 feet, but it takes 60 to 90 minutes to get there, depending on snow and avalanche conditions.

While Temple, a field assistant, digs an impressively uniform 170-centimeter (5-foot) snowpit, Landry walks to a high-tech array of automated instruments gathered on a series of metal towers and arms. These provide real-time data.

The silver cylindrical device on the far end of an arm measures the snow depth by emitting sonar, Landry explains. One sensor reads snow temperature; two others measure air temperature and humidity. There are two wind sensors. Unseen sensors in the snow and in the ground provide other measurements.

Two devices pointing down measure the amount of radiation being reflected off the snow. On another arm, two devices pointing up measure incoming radiation. The difference is used to calculate albedo.

So much science and data. Who needs it? For starters, the Bureau of Reclamation, the cities of Grand Junction and Denver and water-conservation districts around the state. All are stakeholders that help fund the center. Researchers also take advantage of the data, much of which is accessible at www.codos.org.

Ken Curtis, engineer with the Dolores Water Conservancy District, says that although dust has been blowing into Colorado for millennia (Great Sand Dunes is an obvious example), it’s become apparent that since drought years of the early 2000s, dust storms are getting worse. And the dust “does affect how the snow comes off during runoff.”

The immediate data help in knowing how quickly snow will melt, but Curtis says that the bigger value may be in the long-term data. For water managers, big-picture questions loom: Is the dust, indeed, a result of drought? Is it human-caused? Is there a way to control it?

“It’s very important to the San Juans,” Curtis says. “Having a local source is good to have to understand some of the trends.”

The center was a collaboration among Landry, Chris George and Don Bachman. Landry met Bachman in Bozeman, Montana, where Landry completed his master’s. Landry traveled to the Silverton area during summer 2002 to scout the area as fires raged across the drought-stricken state.

“We really considered the whole West,” Landry said.

By 2003, he was gathering data. Landry says the center hopes to continue to grow its stakeholder base to each of the seven states in the Colorado River Compact. Although some of the data are usable only locally, much of it can be extrapolated to understand mountain systems and wider trends.

Although “climate change” isn’t a point of emphasis, it’s something that the data might show.

“We know what we’re doing here will contribute to understanding global change,” Landry says.

After they’ve taken dozens of snowpit samples and catalogued it all in the logbook, Landry and Temple shovel snow back into the pit and tidy it up. Next time, they’ll dig a fresh pit in a nearby virgin plot of snow – one that I haven’t walked on with my dirty boots.

johnp@durangoherald.com. John Peel writes a weekly human-interest column.

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