Up (and Down) a Creek

Here’s what you need to know about the EPA spilling three million gallons of wastewater into a Colorado river.

August 11, 2015

Kayakers on the Animas River on August 6, 2015
Photo: Jerry McBride/The Durango Herald via AP

This week the Colorado’s Animas River looked more like an ad for Tang than the scenic blue ribbon it usually is. Last Wednesday the U.S. Environmental Protection Agency accidentally released three million gallons of heavy metal–laden mining waste, and the toxic surge is making its way downriver. Here’s the latest on what’s going on.

Wait, the EPA did that?

Yes. The agency is typically in the business of cleaning up this kind of mess, but in this case, well, it screwed up—big time. While supervising the drainage of the Gold King Mine near Silverton, Colorado (one of many abandoned mines in the area), workers breached an unstable dam, releasing an unstoppable deluge of the very same toxic wastewater they’d been trying to contain. It took a day before the agency owned up to the accident, and when it did, it underestimated its severity. After first putting the spill at a million gallons, the EPA has now tripled that estimate.

To be fair, the agency was only trying to deal with the mess the mining company left behind in the first place. As NRDC's Bob Deans explains below in an interview with MSNBC's Andrea Mitchell (disclosure), the mine had already been leaking toxins into the river for some time.

What exactly is turning the river orange?

Gold King hasn't been an operational gold mine since 1923, but that doesn't mean it's just sitting pretty. The Denver Post reports that Colorado has approximately 22,000 abandoned hard-rock mines, and their untreated drainage has long been a problem for the state’s waterways. Mining exposes acidic minerals and heavy metals and groundwater can wash them into rivers—the government estimates that 40 percent of Western headwaters have been contaminated this way. Attempts to clean up the mines are few and far between due to the expense, expertise, and special permits such projects would involve.

The wastewater from Wednesdsay’s disaster contains a nasty cocktail of heavy metals, including aluminum, lead, arsenic, and cadmium, though the EPA has yet to release a more specific profile of the spill’s composition. Near the town of Durango, tests released by the EPA on Sunday showed arsenic and lead levels in the Animas peaking at 300 and 3,500 times the historic level, respectively. Those numbers dropped quickly as the water and its contents flowed and dissipated downstream.

Photo: Robert Thigpen/FlickrThe Animas River in 2009.

What’s being done?

As of Sunday, the mine was still spewing out at 500 gallons per minute, but on Friday, the EPA began diverting any newly released liquid into two settling ponds nearby. The agency will eventually treat the waste before discharging it into the river.  

Unfortunately, plenty of the stuff is already on the go. By Sunday night, the plume had traveled more than 80 miles down river to Farmington, New Mexico, which borders the Navajo Nation. This is where the Animas feeds into the San Juan River, a tributary of the Colorado. Though the towns managed to shut off intake valves before the tainted water arrived, authorities are advising residents who have wells within the floodplains of the Animas and San Juan to get their water tested before drinking or using it. Officials are also warning that people, pets, and livestock should avoid contact with the river, and on Monday, the EPA said both the Animas and the San Juan would be closed to drinking, irrigation supply, fishing, and recreation until at least August 17.

Durango and La Plata counties both declared a state of emergency on Sunday, as did the Navajo Nation Commission on Emergency Management. On Monday, Colorado Governor John Hickenlooper followed suit with a disaster declaration for the state. The president of the Navajo Nation has already threatened to sue the EPA for any damages done to his community’s farms and livestock.

What now?

The leading edge of the mustard-hued pollution is no longer visible from aerial surveys, meaning the concentration of the wastewater has begun to dilute. But while the Animas may return to its natural color, what lies beneath may have long-term consequences. Toxic metals that settle in the sediment on the river bottom will become disturbed by runoff during future storms, and close monitoring will be required. USA Today reports that the EPA is working to get the spill area listed as a Superfund site.

Contamination has plagued the Animas and Cement Creek (the site of the initial foul-up) since the 19th century—the Denver Post reports that Cement Creek was declared undrinkable in 1876—but it’s not clear how the latest blow to its water quality will affect the river’s ecology and the people who depend on it. As a test over the weekend, Colorado Parks and Wildlife placed a series of cages in the Animas containing 100 trout. By yesterday only one had died.


onEarth provides reporting and analysis about environmental science, policy, and culture. All opinions expressed are those of the authors and do not necessarily reflect the policies or positions of NRDC. Learn more or follow us on Facebook and Twitter.

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