A winter dust storm March 6 covered the Owyhee Mountains in a dusty shroud that scientists say caused unprecedented snow melting in the already dry watershed.
The dust-on-snow came during five hours of wind that averaged 34 miles per hour and gusted up to 57 miles per hour on ridgelines at the Reynolds Creek Experimental Watershed in the northern Owyhees. Hydrologists at the U.S. Department of Agriculture research area then observed accelerated melting they are still measuring from March 10 to March 16, when a dusting snow covered the dust.
“Nobody on our staff has ever witnessed anything similar,” said Adam Winstral
Snow surveyors with the Natural Resources Conservation Service saw dust on snow as far east at the upper end of the Mores Creek watershed by Idaho City.
“Because its been so dry in the valleys in Oregon and Nevada the wind picked the dust up and carried it here,” said Ron Abramovich, Idaho NRCS Water Supply Specialist.
Reynolds Creek scientists have been working with
hydrologists in Colorado who have observed similar events and are studying the snow-melt rates. In Colorado they have observed snowpacks shortening by several weeks with shifts in the peaks of snow-melt runoff from the dust.
Abramovich said the runoff in the Owyhee River peaked March 16 from snow-melt.
The dust reduces the snow’s ability to reflect sunlight and actually absorbs solar radiation, he said. His staff has taken three-inch core samples of snow that have as much as a half inch plug of dust.
They will move it from the sampling site and a month later a ring of melted snow three feet wide by two feet deep will have form around it.
“That’s just one spot when you spread this much dust over the watershed you know there are impacts,” Abramovich said.
Dust storms were reported in Oregon and Nevada last year after major wildfires. The Holloway fire started August 5 along the Oregon-Nevada border and quickly grew 461,000 acres. In July the Long Draw Fire burned another 582,000 acres.