When Jonathan Thompson first saw the toxic orange sludge roiling through the Animas River, he was “dumbfounded.” He’s a senior editor at High Country News and a resident of Durango, Colorado, which declared a state of emergency following the blowout of the Gold King mine last week. The Environmental Protection Agency (EPA)—which was charged with clearing contamination from this abandoned mine—accidentally triggered the release of three million gallons of toxic wastewater, including arsenic and lead.

Just a week after the disaster, the EPA announced that “analysis shows that water quality for the Animas River from Silverton, Colorado area to the Durango municipal water intake has returned to pre-event water quality levels.” While in the short-term, the river appears to be returning to normal, the blowout at Gold King mine shines a spotlight on abandoned mines and the environmental impact of their acid drainage across the state. Thompson and Grace Hood, another Colorado-based journalist, describe what they’ve seen on the ground over the last week, and what the cleanup process might look like going forward.