The judge has asked the Office of Surface Mining Reclamation and Enforcement to review the environmental impact of an expansion.

The move follows a lawsuit filed by five organizations including Diné Citizens Against Ruining our Environment, San Juan Citizens Alliance, Sierra Club, the Center for Biological Diversity and Amigos Bravos claiming that the mine and OSM’s expansion plan violates the National Environmental Policy Act (NEPA), The Durango Herald reports.

This is the second lawsuit filed by the organizations seeking NEPA review that properly evaluates mercury risks to public health and the environment.

Dinè CARE official said: "This decision confirms the serious problems with the Navajo Mine and the long legacy of pollution that must be addressed at the entire coal complex.

"It also appears that the Navajo Transitional Energy Company and OSM have minimized the analysis on the 50-year-old facility, which is fraught with liabilities."

"The decision affirms the importance of environmental laws and represents nearly 10 years of work by dedicated organizations and lawyers," said Mike Eisenfeld of San Juan Citizens Alliance.

"We refuse to compromise on the recognized fact that our continued reliance on coal-derived electricity takes an extraordinary toll on human life and the resources we depend on. The onus is on OSM to comply with NEPA."

"This decision is a good step towards addressing the pervasive mercury and other coal related contamination found in New Mexico’s rivers, lakes and streams," said Rachel Conn with Amigos Bravos.

The expansion program includes extension of 714 acres to provide coal to the nearby Four Corners power plant through 2016.