These images provided by the Environmental Protection Agency show the mouth of the Gold King Mine tunnel, at left, and the channeled runoff on the mine dump.

(Courtesy EPA)

Southwestern Colorado residents still need to steer clear of the Animas River, after EPA workers accidentally triggered the spill of 1 million gallons of mine wastewater at the abandoned Gold King Mine near Silverton. The plume of muck got into Cement Creek, and then the Animas River. 

Previously: EPA Admits It Triggered Million-Gallon Mine Waste Release

How did this happen?

Southwestern Colorado has a lot of abandoned mines and environmental officials have been in the area for years, working to clear toxic metals and acidic water left behind.

At the Gold King Mine, EPA officials were using heavy equipment for their site investigation to learn the extent of contamination. Not only was there was more mine wastewater than expected, but the water was held back by a dam of soils as opposed to rocks. While the EPA was digging around, water gushed out and started to drain down.

“We typically respond to emergencies, we don’t cause them. But this is just something that happens when we’re dealing with mines sometimes," said Dave Ostrander, EPA Region 8 Director of Emergency Preparedness.

What's been the effect on fish and aquatic life so far? 

Colorado Parks and Wildlife set out a series of baskets along the Animas containing a total of 100 fish in all, essentially using them as canaries in a coal mine. So far, they say, only one fish has died. But it's worth noting that Cement Creek and the upper animas are already troubled waterways with limited aquatic life. Larry Wolk, director of the state's health department, told us earlier that,"For better or worse this particular stream and river have had contaminant issues in the the past and users of the water have been aware of those contaminant issues. A spill of this type is not necessarily changing that unfortunate prior status."

An overview of the Gold King Mine discharge.

(Courtesy EPA)

 What else has the EPA said about their role here?

Though the spill happened on Wednesday, the EPA didn't tell anyone about it until the next business day. On Friday, the agency acknowledged that, and explained that they didn't quite understand what they were dealing with. 

"We really believed it wasn’t as much water as we ended up seeing. As a result, some of our initial communications were not fully accurate,” said Shaun McGrath, an EPA administrator for the region. 

What is the status of the spill Friday evening? 

The mine is still leaking water, and that water contains lead, arsenic, along with cadmium, aluminum, copper and calcium and other pollutants. The EPA is building what's called a settling pond to capture the remaining discharge. 

What's the effect of all this on human health?

For now, the health impacts of the spill aren't known. But the city of Durango has shut off water connections to the Animas river. They're asking residents to conserve water, as the city has a 10-day supply in reserve. And recreational boaters and anglers are not allowed on the river for now. Agricultural users in the area have also been asked not to water crops. 

What happens next?

The plume will move downstream through New Mexico and Arizona, from the Animas, to the San Juan, to the Colorado rivers and eventually the Gulf of California. That's because things are still playing out with health, and fish and other aquatic life are affected, and downstream impacts are unknown.

New Mexico officials are angry the EPA did not inform them soon enough about the pollution floating downstream. The state's environment secretary, Ryan Flynn, said Friday that the agency downplayed the danger the contamination posed to wildlife, adding that potential harm can't be known until the contents of the wastewater and their concentrations are known.