The Bureau of Land Management (BLM) estimates that there are currently 2,700 abandoned hard rock mines in need of environmental clean up. Nevada, nicknamed the “Silver State,” has the most, with an estimated 1,100 sites raising environmental concerns.

While crews begin the arduous task of cleaning up Colorado’s Animas River — where contamination by heavy metals and toxins leaked from an abandoned hard rock mine turning the water orange — thousands of other natural sites across the American West remain at risk from similarly hazardous defunct quarries.

Bureau of Land Management's count of abandoned mine lands by state and project status as well as estimated counts of sites with environmental hazards. Most of the sites are hardrock mines.

Abandoned hard rock mines can leach heavy metals into the water table or produce acid mine drainage, where chemicals mix with air and water to create toxic runoff that can impair aquatic life and public health.

“In this day when we’re seeing increasing demands on fresh water and seeing the effects of climate change, it’s important we're not allowing our existing water supplies to be polluted by mining,” said Bonnie Gestring, a program director for Earthworks, a conservation group based in Montana. “It's important for people to understand how pervasive this problem is. The EPA estimates that more than 40 percent of headwaters of western waterways are polluted by abandoned mines.”

However, finding resources to fund the necessary cleanup has proven challenging, with problematic policies and legal hurdles making progress slow.

Today’s problem of abandoned mineral mines stems from a law in 1872 that allowed prospectors to dig for precious metals without any requirement to plug mines or otherwise clean up environmental damage. Although parts of this law changed in 1981 to require mine companies to clean up new sites, over a hundred years worth of old mines were left in the government’s hands.

Given how old a lot of the abandoned mines are, Kim Hannula, a geologist professor at Fort Lewis College in Durango, Colorado, said it’s impossible to blame any one party for the environmental dangers they pose.

“It’s a hard chemical problem, it’s a hard geological problem, it’s a hard political problem,” she said

Hannula added: “I think people would like to have one bad guy who they can blame,” but those who created the problem “have been dead for 100 years.”

McKinley-Ben Miller, Deputy Division Chief at the Division of Environmental Quality & Protection at the BLM, said: “If there is no responsible party, then it’s the taxpayer that has to foot he bill. But we don’t have the money to do it.”

Efforts to clean abandoned hard rock mines are particularly cash-strapped since they don’t benefit from a dedicated revenue source for abandoned mine cleanup in the same way that coal mines do. As part of 1977’s Surface Mining Control and Reclamation Act, coal miners pay a “coal fee” to the Department of the Interior. States can use that money to address safety and environmental issues at abandoned coal mines. A proposal to create a similar fund for hard rock mines has been on President Barack Obama’s budget proposal since 2012, but has not been implemented.

Though Rep. Raúl Grijalva, D-Ariz., recently introduced the Hard Rock Mining Reform and Reclamation Act of 2015 to create such a fund, it has faced pushback by the mining industry.

The National Mining Association (NMA) has historically opposed a hard rock reclamation fund and “flatly opposes” Grijalva’s bill, saying that proposed payment levels are too onerous, according to Luke Popovich, vice president of external communications at NAM.

“The U.S. is already a high cost region to mine,” Popovich added. “We can accept a modest royalty; we cannot accept a royalty that is dressed up as a means of dealing with abandoned mines but is designed to destroy the industry.”

Ironically, the Clean Water Act of 1972 can also be a barrier to mine cleanups.

“The state of Colorado, local government and even some larger NGOs are reluctant to work on or try to clean up inactive or abandoned mines because of third-party liability,” said Bruce Stover of the Colorado Division of Reclamation, Mining and Safety. “Most of these projects are only amenable to partial treatment, which will get you 70 or 75 percent of the water quality you want under the Clean Water Act. That helps but the remaining pollution is then on you. So the only people that can do this water treatment is the EPA [Environmental Protection Agency] or the U.S. Forest Service — the states are not touching these projects where water treatment is involved.”

Even if so-called “Good Samaritan laws” were passed that would remove such liability, cash remains an issue.

“We don’t have enough funding to do it all,” Stover said. “Every year we have enough to do five to six environmental projects but when you have hundreds to do, it's going to be decades before we finish. I know there’s a lot of pitfalls and difficult but a dedicated fund would be the biggest help.”

Additional reporting by Allen Schauffler