State agency examines Colorado headwaters areas
DENVER (AP) – Poor surface-water quality in some Colorado headwaters areas isn’t due to human activities like mining but to geology, according to a new Colorado Geological Society study that examined water quality.
The report could help wildlife managers avoid restocking fish where they can’t survive because the water is naturally acidic, and it could help to better focus environmental cleanup efforts, said co-author and former Colorado Geological Survey Deputy Director Matt Sares. It also could help regulators who must set stream water-quality standards.
The agency launched the study after working with the U.S. Forest Service to identify environmental problems related to abandoned mines. During that work, researchers found that water upstream of mine sites wasn’t always as pristine as they thought it would be.
Intensely hot water circulating in the earth’s crust has changed the composition of some rock by dissolving some minerals and depositing others, Sares said. That can increase concentrations of acid-producing minerals like pyrite and lower acid buffers.
The Colorado Geological Survey study identified streams in 11 headwater areas where surface water is acidic and has high concentrations of metals such as aluminum, manganese and iron, even upstream of any significant human impacts.
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.
Of 101 water samples that researchers took, 86 were in areas where there was no influence from activities related to mining. Less than one-fifth met state water-quality standards for all tested parameters, the report said.
“For most people who get water from municipal systems, it’s not an issue because they do filter out those contaminants in the process of delivering drinking water,” Sares said. “The biggest issue is for aquatic life. There are places where cold water trout are not able to live or reproduce.”