By Jolie Breeden

Oil spills and fracking waste have taken the lion’s share of attention when it comes to technological threats to the nation’s water, but another hazard has recently come to the fore—pollution stemming from hard-rock mining.

The risk isn’t at all new, but early this month an especially colorful example of the hazard emerged when three million gallons of toxic wastewater from an abandoned mine gushed into the Animas River in Colorado. The August 5 spill turned the vital waterway an orangeish-yellow and impacted drinking water supplies, tourism, and agriculture as far south as New Mexico.

As of August 12, the river’s water quality had returned to levels noted before the incident and it was reopened for recreational and other uses, according to Reuters. While the spill was significant, there was a sense that the situation wasn’t as bad as it might have been.

“We don't anticipate that we're going to have an environmental tail on this that's going to have significant repercussions for a long period of time,” Colorado Governor John Hickenlooper said on Colorado Public Radio. “We were very fearful at the beginning, but as close as we can measure and observe, I think we dodged a bullet.”

While that may be so, the state and the nation are still facing down the barrel of a gun loaded with potential incidents. The Colorado Bureau of Land Management counted 2,751 abandoned hard-rock mines on the state’s public lands and there could be as many as 550,000 nationwide. These unmaintained and sometimes forgotten properties fill up with water from various sources, which then mixes with the minerals and heavy metals such as cadmium, arsenic, and lead. The result is great reservoirs of toxic, acidic fluid known as acid-rock or acid mine drainage.

Often, this contaminated concoction leaks slowly into surrounding water supplies, while larger discharges are held at bay by concrete bulkheads installed by mine owners. But in heavily-mined areas such as Colorado, those bulkheads can push the tainted water into a web of connected underground channels, creating unpredictable conditions experts have long feared would end in a disaster like the Animas spill.

“Most of us in the industry have been predicting this for 30 years,” Mark Gibson of Denver-based Kyklos Engineering told The Guardian. “It’s basic physics. Where is the water going to go?”

The situation points to a pressing need to remediate the toxic water held in mines (although, ironically, the August spill was caused when the U.S. Environmental Protection Agency breached a bulkhead in just such a cleanup attempt). While the technology is available, it’s costly and the Gold Rush-era laws that regulate mine owners don’t provide much incentive for taking on the expense.

There's some criteria in the old law, existing law, that really makes it so no one's going to do anything,” Hickenlooper told CPR. “We should change that. This has been going on for 50-100 years. Enough is enough.”

Currently, much of the cleanup falls to the overburdened EPA, although a bill in Congress might change that. The Hardrock Mining Reform and Reclamation Act of 2015 would establish royalties on new and existing hard-rock mines to create a fund to address abandoned mine cleanup.

The bill is one of many in a long line of attempts to reform the hard-rock mining industry, which sees such efforts as financially burdensome and economically shortsighted. Still, officials such as Colorado’s La Plata County Commissioner Gwen Lachelt, hope that the attention from the Animas spill might help the issue gain a foothold.

“A similar system is already in place for abandoned coal mines, so there’s no practical reason it can’t work for hard-rock mining too,” Lachelt wrote in an opinion piece for the New York Times. “I’m not alone in wanting to stop this reckless pollution from endangering the rest of our communities and our environment.”