Uranium mining company Energy Fuels Resources announced its plans to reopen its mine situated six miles south of the Grand Canyon’s South Rim entrance.

The company was given federal approval by the U.S. Forest Service who conducted an environmental study on the site more than 25 years ago in 1986.

In response, several groups, including the Grand Canyon Trust, Center for Biological Diversity, Sierra Club and Havasupai Tribe, have banded together to file suit against Forest Supervisor of the Kaibab National Forest Michael Williams as well as the Forest Service as a whole.

The plaintiffs cite the group’s failure to comply with environmental, mining, public land and historic preservations laws in giving the mine a green light, arguing that since the completion of the Environmental Impact Statements (EIS) in 1986 “significant new information and changed circumstances have emerged concerning the Mine’s operations and adverse environmental impacts.”

Despite such developments, the plaintiffs state the Forest Service “decided not to ‘supplement’ the 1986 EIS” or “require a modification” of the plan of operations put forth more than two decades ago.

Among the developments that have occurred since the mine was first approved is the regulation of radon gas, a substance the plaintiffs fear will pollute the area should the mine go forward.

While uranium and radium are naturally-occurring radioactive materials, the Environmental Protection Agency (EPA) warns that once they are exposed or concentrated through mining, they become technologically-enhanced in such a way that renders them radioactive and capable of contaminating the surrounding soil and water.

Since 1879, the EPA reports, uranium mine workers began being diagnosed with lung diseases, including cancer, and that workers today are directly exposed to radiation hazards.

According to The Guardian, the energy company’s spokesman has publicly disputed these claims, stating that the Forest Service “looked at that review with modern eyes” in determining once again that the regulations were adequate. He further pointed out that the mines are “tiny,” accounting for about 20 acres total.

However, as The New York Times reports, the Department of Energy and other agencies have evaluated nearly 700 mine sites in need of remediation – a project costing the government hundreds of millions of dollars and that some complain has been largely ineffective.