EUREKA, Nev. – Conservationists are trying to put the brakes on plans to mine hundreds of millions of pounds of the metallic element molybdenum from an open-pit mine in north-central Nevada.

The Reno-based Great Basin Resource Watch has asked the U.S. Bureau of Land Management to rescind the final environmental impact statement it issued last month when it approved the final record of decision for the Mount Hope project in Eureka County.

Officials for the mining company Eureka Moly LLC say the mine 23 miles northwest of Eureka contains 1.3 billion pounds of the element used as an alloy agent to strengthen steel, including the manufacturing of solar cells, engines, airplanes and military equipment.

The mine near U.S. Highway 278 is expected to provide an average 400 long-term jobs in the area with a peak employment of 615 personnel during construction activities.

But the environmentalists say it can be highly toxic and that the BLM’s environmental review was insufficient.

The Eureka County Commission has raised concerns but hasn’t formally opposed the project, which has been in the works for the past six years.

The project area covering a total of about 37 square miles would disturb about 8,100 acres of public land and 260 acres of private land.

The project poses a threat to three watersheds, with the Roberts Mountains to the west and the agricultural fields of Diamond and Kobeh valleys to the east and south, Great Basin Resource Watch executive director John Hadder said.

Specifically, the group’s appeal of the EIS claims BLM violated the National Environmental Policy Act and failed to prevent “unnecessary or undue degradation” of public land resources, as required by the Federal Land Policy and Management Act and BLM’s implementing regulations when it approved the project.

It also said BLM’s decision is based on incorrect and unsupportable assumptions and positions regarding Eureka Moly LLC’s alleged “statutory right” to have the project approved under the mining law.

“The final EIS does not provide sufficient detail to develop clear mitigation for these impacts,” Hadder said. “The wait and see approach to mitigation plans of Eureka Moly LLC, which has not been challenged by the BLM or the state of Nevada, could ultimately cost the nearby communities in irreparable environmental damage and irretrievable losses in resources to the county.”

The state director will review the petition, BLM spokeswoman JoLynn Worley said. Meanwhile, the decision and final EIS remain in effect. She said there is a 10-day deadline for a review, but there is no penalty in the regulations if the deadline is exceeded.

The project will include a 230-kilovolt transmission line, a water well field and other facilities.