By digging in the muck of Rocky Mountain ponds and lakes, scientists have been able to establish an accurate historic record of how human activities have increased the amount of dust falling on high country snowpack.

Using satellite images and analyzing the dust, other researchers have been able to pinpoint specific sources, including off-road vehicle disturbances, livestock grazing and oil and gas development on the Colorado Plateau.

“It's profound,” said researcher Tom Painter, director of the snow optics laboratory at the University of Utah. “Areas that are actively disturbed release 1,000 times more dust,” Painter said, adding that dust layers in 2009 caused the snow pack to melt 45 to 48 days earlier than normal.

Areas that haven't been disturbed by human activities release very little dust, Painter said.

“This has huge impacts on hydrology and snow cover,” Painter said, explaining that water managers have to account for changes in runoff as they plan the operation of reservoirs and diversions.

“For us, the bottom line is, how much water are we going to get, and when do we get it,” said Grand Junction-based Dan Crabtree, water management group chief with the U.S. Bureau of Reclamation. The federal agency manages most of the region's major water projects.

The timing of spring runoff has implications for water managers across the West, but Crabtree used the example of the Black Canyon of the Gunnison to illustrate how it affects the Bureau's planning.

Since a federal court recently decided how much water should flow through the Black Canyon, the Bureau of Reclamation has to take that amount into consideration as it plans how it will fill the large reservoirs near Gunnison. Figuring out when the flows in the mountain tributaries will peak is a crucial part of the equation, Crabtree said.

Painter said research in the last few years has enabled scientists to look back about 5,000 years. Lake sediments show a dramatic increase in dust deposition coincided with the settlement of the West, beginning in the late 1800s, he explained.

The dust levels stayed high through the early 1900s and then declined in the 1930s, when new grazing laws changed the way ranchers ran their herds of cattle.

Overall, the amount of dust being released since the advent of human disturbance is 500 times greater than prior to the disturbance of the West, Painter said.

A more detailed examination of the past eight years shows a relatively stable level of dust until 2006, when there was a big jump, as oil and gas drilling activities on the Colorado Plateau increased exponentially.

In 2009, the amount of dust falling on the snow increased 20-fold, he said.

Painter tied the dust issue to larger concerns about climate change. Earlier snowmelt caused by the dust could trigger a spiraling effect of warmer temperatures. If the mountain snowpack melts earlier, the darker mountain surfaces will likely absorb more heat, potentially causing temperatures to climb even faster than predicted.

The U.S. Geological Survey maintains web site with updated information on western dust storms, including photos and satellite videos: http://bit.ly/3mnF2S