Getting the Dirt on Dust in the West

After examining layers of soil in the American West, scientists from the University of Colorado say the region is much dustier than it was before Europeans arrived in America. And the composition of today's dust is worrisome.

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The theme movie for the American West might well be "There Will be Dust." The western U.S. is a lot dustier than it was before European settlers arrived. Research indicates that railroads and livestock and agriculture have caused a five-fold increase in dust. And fragile ecosystems may never fully recover from the damage.

As NPR's Jeff Brady reports, the damage to the environment continues.

JEFF BRADY: Here's an iconic Western image for you: hundreds of longhorn cattle being herded across the frontier by a couple of cowboys on horseback, a huge cloud of dust in their wake.

(Soundbite of song, "Rawhide Theme")

Mr. FRANKIE LAINE (Singer): (Singing) Move 'em on, head 'em up, Head 'em up, move 'em out, Move 'em on, head 'em out Rawhide! Set 'em out, ride 'em in, Ride 'em in, let 'em out, Cut 'em out, ride 'em in Rawhide.

BRADY: Dust is a part of Western life, even today. Ask the folks who ski in Telluride, Colorado. Pat Valendorf(ph) works at a ski rental shop there. And the dust storms even have a name. They're called San Juaners, after the San Juan Mountain range.

Mr. PAT VALENDORF (Employee, ski rental shop): It typically happens in the spring. And it comes up from the southwest and it's just a heck of a windstorm, you know. And the sky will turn brown and kind of bright red and after a day or two of that, you know, it'll kind of go on and you'll see the dust on the top of the mountains and the snow will turn red.

BRADY: There was a time when dust storms like this were much smaller events, according to Jason Neff. He studies how natural systems work at the University of Colorado at Boulder. Neff says just a few hundred years back, across more of the arid west there were hard crusty layers on top of the soil.

Professor JASON NEFF (Geological Science, University of Colorado at Boulder): You still see these in places around Canyonlands National Park. There are signs, Don't bust the crust. They're very fragile. But they're fragile to footsteps,. They're fragile to hooves landing on them. They're incredibly resilient to wind.

BRADY: Neff says most of these crusts were broken up long ago. He and his colleagues wondered about the environmental impact. Mountain lakes are really good dust collectors, so they examined the layers of soil at the bottom of some lakes. Up until the 1800s, just very thin layers of dust were deposited each year. And then...

Professor NEFF: It's almost like a switch was turned on. Around 1800, 1850, late 1800s, all of a sudden the dust started accumulating in these lakes in a dramatic way.

BRADY: The amount of dust increased by more than 500 percent. It peaked around 1900, when about 40 million head of livestock were grazing on the western range. Neff says a study shows just how fragile western deserts are.

Professor NEFF: These are not the same types of ecosystems that we find in the middle part of the U.S. or that we find in the eastern U.S. Once disturbed, once these crusts are destroyed, once we change the sort of fabric of the soils in the western U.S., it's hard to go back from that.

BRADY: Since 1900, the amount of dust flying around the west has declined slightly, but Neff says something new is emerging.

Professor NEFF: We now see the signs of industrial activity, air pollution, agriculture fertilizers, all those now appear in the dust that is moving. So even while the amount of dust seems to have declined a little bit, the composition of that dust now reflects a lot of other compounds that weren't there before.

BRADY: That contaminated dust is making its way into the fragile ecosystems of those mountain lakes and gradually changing them. Scientists around the region are closely watching these lakes and figuring out how to protect them.

Jeff Brady, NPR News, Denver.

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