Thousands of abandoned mines in Colorado are leaking toxic water, but Congress finally has a solution in sight

PARK COUNTY — Polluted water leaking from thousands of abandoned mines in Colorado’s mountains is turning wetlands orange and dumping toxic dissolved metals in the headwaters of many of the state’s rivers.

But people who want to fix the problem are hampered by the very federal laws meant to protect the environment.

Organizations and local governments that want to fix the acidic drainage from a mine outside of Alma — and the hundreds of thousands of other abandoned mines across the West — are hopeful about new legislation under consideration in Congress. By removing liability burdens, the bill would finally give them more leeway to stop the pollution seeping into the streams relied upon for drinking water, recreation, and fish and animal habitat.

“This is a problem that is generally unseen to the general public,” said Ty Churchwell, a mining coordinator with Trout Unlimited who has worked for more than two decades to create better policy for abandoned mine cleanup. “As long as they can walk over to their tap and turn it on and clean water comes out, too often people don’t think about what’s happening at the top of the watersheds.

“But it’s a horribly pervasive problem, especially in the West. It’s hurting fisheries, tourism and recreation, domestic water — it’s a problem that needs to be solved.”

More than 23,000 abandoned mines dot public and private land across Colorado’s mountains and hills, according to the Colorado Division of Reclamation, Mining and Safety. At least 500 of those measurably harm nearby water quality by leaking acidic water packed with dissolved metals and sulfates. Those substances can turn streams and wetlands an unsettling orange.

In high-enough concentrations, the acidic mine drainage can kill aquatic ecosystems.

Acidic drainage pollutes at least 1,800 miles of Colorado’s streams, according to a 2017 report from state agencies. About 40% of headwater streams across the West are contaminated by historical mining activity, according to the Environmental Protection Agency.

But nonprofits, local governments and other third parties interested in fixing the problem are deterred by stringent liability policies baked into two of the country’s landmark environmental protection laws: Superfund and the Clean Water Act. Anyone attempting to clean up sources of pollution at a mine could end up with permanent liability for the site and its water quality.

“When I talk to clients and lay out exposure under Superfund and the Clean Water Act, they just throw up their hands and say, ‘John I’d like to help, but I can’t take that risk,’ ” said John Watson, an attorney who practices environmental law.

State officials, nonprofit leaders and lawmakers for decades have worked to find a solution that allows outsiders — called “good Samaritans” — to mitigate the pollution infiltrating thousands of miles of streams.

That work may finally bear fruit as Congress considers a solution that advocates believe has a good chance of passing. Federal legislation to address the problem cleared the Senate with unanimous support, and on Wednesday it passed out of the House Transportation and Infrastructure Committee — the farthest any good Samaritan mine cleanup bill has proceeded.

Perfect as the enemy of the good

Last week, large machinery rumbled at the abandoned mine outside Alma as contractors worked to grade a hill of mine waste, flattening the yellow- and orange-tinged rocks.

Since the mine’s opening in 1891, polluted water has flowed out, traveling through the pile of mine tailings and waste rock, which contain elevated levels of arsenic, iron, lead, copper, mercury, molybdenum and zinc.

Zinc, which is toxic to fish in elevated concentrations, is one of the major concerns at the site, where the collapsed mine entrance spews about an eighth of a pound of dissolved zinc every day. The water becomes even more polluted after it passes through the waste piles.

Water testing showed that the amount of dissolved zinc in the water increased by a factor of 14 after the mine water traveled through the waste.

That water then dumped into 4 acres of wetlands below the site — and eventually into Mosquito Creek, which drains into the Middle Fork of the South Platte River south of Alma.

But now, after work by Trout Unlimited, the mine water travels around the mine waste via a lined channel that keeps the contaminated water from seeping into the dirt. Contractors will also reshape the mine waste — which covers about an acre — and enhance it with substances like crushed limestone to trap and neutralize metals when water passes through.

The hill then will be covered and revegetated.

When completed in October, the $244,000 project should measurably improve water quality in the creek, said Jason Willis, director of the nonprofit’s Western Abandoned Mine Lands Program. Though work is only halfway done, the wetlands already appear less orange.

If good Samaritan laws were in place, Willis said, Trout Unlimited could address the source of the pollution at the mouth of the mine.

“We could be doing this project a little more holistically,” he said.

Under current law, Trout Unlimited would have to assume permanent liability for the pollution if it decided to address the discharge at its source. The nonprofit would also be required to treat 100% of the pollution, which is not always possible or financially feasible, said Churchwell, the group’s mining coordinator.

“Our contention is that if we can remove 25%, 50%, 75% — isn’t that better than none at all?” he said. “And none at all is the program that we have today. We can’t let the perfect be the enemy of the good.”

Even state agencies shy away from treating toxic mine drainage at its source.

Colorado’s Inactive Mine Reclamation Program addresses safety concerns from mine openings and pollution from mine waste and tailings, but it does not treat polluted water at the point of discharge, program director Jeff Graves said in an email.

“CERCLA (the Superfund law) and Clean Water Act create a situation where a Good Sam, in this case the State, could be liable for long-term water treatment or remediation at a site where the State undertakes reclamation activities,” he wrote.

No constituency for orange water

Now Congress is attempting to remove that barrier. The pending bill, the Good Samaritan Remediation of Abandoned Hardrock Mines Act of 2024, would create a pilot program for up to 15 remediation projects led by good Samaritan organizations. A number of Colorado lawmakers are co-sponsors of the bill, including both senators and Reps. Brittany Pettersen, Joe Neguse, Lauren Boebert and Jason Crow.

Under the bipartisan legislation, a good Samaritan cannot be someone who had a role in the creation of the mine. Good candidates include state agencies, counties, watershed groups and other nonprofits. A site can only be eligible for the program if there is nobody remaining to be held accountable for the original mining and pollution.

Many abandoned mines stopped production before major legislation was enacted to hold miners responsible for environmental damage. While the worst sites are remediated under the Superfund law, many medium and small sites do not qualify — even though they, too, contribute pollution to soils and waters, Churchwell said.

A good Samaritan law could allow others to fill the void.

Gov. Jared Polis’ administration has thrown its support behind the legislation. Dan Gibbs, executive director of the Colorado Department of Natural Resources, in January wrote a letter urging senators to approve the bill.

“Previous bills over the past 25 years have attempted to strike a balance between incentivizing would-be cleanup proponents while protecting against further environmental harm, but have not garnered sufficient support to move forward,” Gibbs wrote in the Jan. 9 letter. “This Bill strikes that balance, and has gained broad support from the mining industry, state and local governments, sportsman groups, and conservation organizations.”

One of the state’s biggest water providers also supports the concept of a good Samaritan bill. Denver Water draws nearly half of its supply for 1.5 million people from the South Platte River basin — the same basin that the mine site outside Alma drains into.