The Perpetual Pollution Problem; Acid Mine Drainage in the Rocky Mountains
By: Anica Bareis-Golumb
While driving west on I-70, there are views of beautiful trees, snow-capped mountains, and also piles of orange/yellow rock dispersed through the trees. These orange scars on Colorado’s hillsides are abandoned hard rock mines and the piles of tailings left behind. Tailings are the byproduct of mines that turn an orange hue over time as they are exposed to the elements. Colorado has nearly 23,000 inactive and abandoned mines out of an estimated 150,000 abandoned mines in the United States. These mines not only pose risks for the curious off-trail hiker who could fall into a collapsed mine, but they also pose the greatest threat to Colorado water quality through the perpetual pollution of acid mine drainage.
When hardrock mines are not closed and remediated properly, minerals and metals are exposed to the elements, leading to acid mine drainage and other pollution. Acid mine drainage occurs when exposed sulfide minerals, such as pyrite, react with oxygen and water to create sulfuric acid. Sulfuric acid is very corrosive, directly burning and killing plants and aquatic life. When sulfuric acid dissolves in water, it lowers the pH of a nearby stream over time. These waterways can have a pH of 4 or lower, which is considered “acidic,” similar to battery acid. Acid mine drainage is a perpetual pollution problem, and many hard rock mines across the western United States require water treatment for hundreds to thousands of years.
Problems associated with acid mine drainage include contaminated drinking water supplies, disrupted growth and reproduction of aquatic plants and animals, and the corroding effects of the acid on parts of infrastructures such as bridges. Common Colorado fish species, including Brook trout, Rainbow trout, and Cutthroat trout, are especially sensitive to acidic waterways and cannot reproduce or live in acidic waterways. Colorado has a large tourist fishing industry that attracts fly fishers from around the world. This has led to nonprofit organizations, such as Trout Unlimited, to be actively invested in the cleanup and remediation of acid mine drainage from abandoned mines in Colorado.
Mining in Colorado began as early as 1858 and was the economic driver of the area, culminating in the admittance of Colorado to the Union in 1876. At various times throughout its history, Colorado was the leading U.S. producer of gold, silver, molybdenum, lead, zinc, uranium, and tungsten. Mining was the largest economic sector of the state until the early twentieth century, and most mines were abandoned by the 1940s. The US or Colorado didn’t adopt any regulations for closing and reclaiming mines until the 1970s, leaving the majority of mines in Colorado just as they were the day miners walked away from them. This also means that the majority of abandoned mines in the state don’t have owners or a responsible party that can be held accountable for funding cleanup.
CERCLA, the Comprehensive Environmental Response, Compensation, and Liability Act, was enacted by Congress in 1980 to respond to the cleanup of contaminated sites that pose a “significant threat to human health.” These sites are colloquially referred to as “Superfund” sites, and there are 1,340 Superfund sites currently on the United States National Priorities List. Superfund sites can be abandoned chemical factories, landfills, ammunition testing areas, abandoned mines, and others. Colorado has multiple Mine Superfund sites, such as the Captain Jack Mill, Gold King Mine, and Idarado Mine. These large mine sites pose such a direct threat to drinking water quality that they have received federal funding under CERCLA for cleanup. The issue is the thousands of other mines that continue to pollute Colorado’s streams without rising to the level for Federal funding under CERCLA.
A major component of CERCLA is to impose strict liability on the landowner and previous owners who contaminated the site. Although this has helped hold multiple parties accountable and fund cleanup of many sites, it has inadvertently created an impediment for good Samaritans and nonprofits to clean up smaller sites. Nonprofits are reluctant to remediate sites because as soon as they touch contamination, they can be held liable.
Finally, after 15 years, Congress passed the "Good Samaritan Remediation of Abandoned Hardrock Mines Act of 2024.” The bill requires the Environmental Protection Agency (EPA) to establish a Good Samaritan pilot program. Under the program, the EPA may issue certain permits to allow Good Samaritans to remediate historic mine residue at abandoned hardrock mine sites to protect human health and the environment without being subject to enforcement or liability under specified environmental laws for past, present, or future releases, threats of releases, or discharges of hazardous substances or other contaminants at or from the abandoned mine site. The bill was supported in the House by Colorado Representatives Diana DeGette, Brittany Pettersen, Joe Neguse, Lauren Boebert, Jason Crow, and Yadira Caraveo and in the Senate by Colorado Senators John Hickenlooper, and Michael Bennet. Senator John Hickenlooper stated, “if someone, a good Samaritan, comes along and wants to help try to fix [an old mine leaking pollution] and they’ve got a great idea … they can’t do it because the moment they touch anything to do with that pollution, they own it. In other words, they can be sued. This is all about trying to let people clean up the mess that people made a century ago without being liable for it.” The Good Samaritan pilot program will begin with 15 pilot projects, and groups like Trout Unlimited are hopeful that one of their projects will be selected as one of the pilot programs. Ultimately, many feel that this is a positive step forward for addressing Colorado’s perpetual pollution problem of acid mine drainage.