The estimated 3 million gallons of orange sludge from the Gold King Mine moved through Durango in about three days, and it left behind a layer of heavy metals that drew concern for this spring’s runoff. But those concerns may not be warranted, some environmental experts say.
“When you have more spring runoff, you have a lot more turbulence, so sediments can get remobilized,” said Peter Butler, a coordinator of the Animas River Stakeholders Group.
“However, usually the lowest metal concentrations we see throughout the year are during spring runoff, and that’s because you have so much dilution. So I’m not really expecting an issue.”
Scott Roberts, an aquatic biologist with Mountain Studies Institute, said water samples from the Animas during storms in October show little sign of increased metal concentrations.
“I think most people were concerned with the sediment not only deposited around the river margin, but also at the bottom of the channel,” he said. “But it’s amazing how much it seems to already have washed off with the few storms we’ve had. You don’t see a lot of evidence left.”
The Environmental Protection Agency’s temporary water treatment plant can handle 900 to 1,200 gallons per minute. Currently, the facility treats only discharges from the Gold King Mine, which averages 525 gallons per minute.
Mine discharges usually increase in the spring because of more ground water movement but are diluted in the runoff.
“But we may be dealing with a whole different ground now,” Butler said. “Nobody really knows what the flows are going to be like. That’s why the EPA oversized the treatment there, so they have the capacity to handle it.”
The EPA said in a prepared statement it plans to monitor before, during and after spring runoff.
In the meantime, state health officials are developing a notification stakeholder group to address how best to notify local governments and agencies if a spill occurs.
Health officials added a second monitoring station on Cement Creek above the confluence with the Animas River. The department is coordinating with federal agencies on a long-term monitoring plan for the entire watershed.
“We’re very lucky the disaster did not have a long tail,” Gov. John Hickenlooper told The Durango Herald on Wednesday. “The consequences aren’t as dire as many of us first thought.”
Still, state water experts say they don’t have a full picture of the impact the spring runoff might have.
“I don’t know, and that’s a problem for me,” said Patrick Pfaltzgraff, director of the Colorado Water Quality Control Division. “I want to have some certainty, and where I don’t have certainty as a water-quality professional, I want to have some process in place to respond to that.”