A mine that spilled into the Animas River north of Silverton did not impact water quality, according to the Environmental Protection Agency, which collected samples and analyzed the data.
It was discovered Oct. 9 that the Silver Wing Mine was discharging more than normal, discoloring the Animas River downstream to about Eureka Gulch.
The Silver Wing Mine is listed in the EPA’s Bonita Peak Mining District Superfund, which consists of 48 mining-related sites contributing to degraded water quality in the Animas River.
The EPA reported the color of the Animas River had returned to normal by Oct. 10.
The agency has not started work on the Silver Wing Mine, however, and it is unclear what caused the uptick in discharges.
“Inspections show no blockages or changes to the structural integrity of the mine,” EPA spokeswoman Katherine Jenkins wrote in an email.
The EPA collected water samples Oct. 10 that indicated no adverse impacts to downstream drinking water or agricultural water use associated with the release from the Silver Wing Mine.
“The data taken from nine sampling points – including the Silver Wing Mine adit and continuing downstream to the town of Durango – indicates increased metals concentrations emanating from the mine, resulting in slightly elevated metals concentrations about 4 miles below the mine,” Jenkins wrote.
The EPA says metal concentrations were not elevated in the Animas River at Silverton or Durango.
“The results from two sampling locations in Durango are well within the range of concentrations previously observed during seasonal sampling events. Impacts to aquatic life, if any, will be limited to the Animas River in the immediate vicinity of the Silver Wing Mine and upstream of Silverton,” Jenkins wrote.
Peter Butler, one of the founders of the now-defunct Animas River Stakeholders Group, said previously the Silver Wing Mine historically has discharged acidic drainage from its portal.
The Silver Wing Mine was identified in the Stakeholders Group’s list of the top 33 mine portals and 34 mine waste piles that account for 90% of the heavy-metal loading in the Animas River watershed.
“It’s definitely one that could use attention,” Butler said.
The owner of the mine, Steve Fearn, who was also one of the Stakeholders Group founders, died in April 2018.