From the Associated Press (Catharine Tsai) via The Denver Post:
In southern Colorado, the headwater areas included the Silverton and Lake City areas, the Platoro-Summitville area, the East Trout area in Mineral County, the Kite Lake area in Hinsdale County, and the Rico and La Plata mountains. They also included the Ruby Range area encompassing Mount Emmons by Crested Butte, the Grizzly Peak area south of Aspen and Leadville, the Red Amphitheatre area near the Climax mine, Twelvemile Creek and the Montezuma stock area. The Rabbit Ears and Never Summer range areas in northern Colorado also were included.
More coverage from Chris Woodka writing for The Pueblo Chieftain. From the article:
Researchers found rocks in these areas were altered by intensely hot water during the volcanic activity during Colorado’s geologic past. Some minerals were dissolved, while metal-sulfide minerals like pyrite (fool’s gold) were deposited. When the rocks were exposed at the surface, they interacted with oxygen to form iron oxide minerals, like a rusted car. The striking yellow, orange and red colors that can inspire awe also contribute to acid rock drainage, and the process has continued for millions of years.
By determining the natural processes, the state hopes to be able to determine background water quality to differentiate between natural effects and man-caused disturbances such as mining, said Matt Sares. “This study does not determine a cause for acid drainage in every case,” Sares said. “It identifies areas where you might not want to put in a mine or develop a domestic water supply.”[…]
“While there is increased potential, the study did not always find pollution in areas with these formations,” Sares said.
More coverage from Dale Rodebaugh writing for The Durango Herald. From the article:
Acid rock drainage occurs when sulfur displaced by oxygen combines with water to produce weak sulfuric acid. The acidic water then dissolves minerals from the bedrock and often adds significant amounts of dissolved metals to streams. The geologists who did the research collected 101 water samples in the 11 headwaters areas. The project lasted four years. Funding for the study came from the Colorado Geological Survey through severance taxes derived from the production of gas, oil, coal and metallic metals.
More water pollution coverage here.