BOISE - A coalition of conservation groups and the Nez Perce Tribe are challenging the U.S. Forest Service's approval of a gold mining company's plan to reopen a 4-mile road in a central Idaho wilderness and drill core samples to find out if two of its claims are profitable enough to be mined.

The Idaho Conservation League and four other groups earlier this month filed an objection with the federal agency as a first step in a potential lawsuit.

The groups contend that the Forest Service's December approval of American Independence Mines and Minerals Co.'s plan in the Frank Church River Of No Return Wilderness exceeds limits on activities set out in a 2002 federal lawsuit.

The plan authorizes the company to make 571 motorized trips into the wilderness area to build 11 drill pads. Vehicles would include four-wheel-drive pickups, a dump truck, a flatbed truck, a bulldozer and a small excavator.

"The mining company has many, many less destructive tools available to determine whether these claims are valid that are more appropriate to this special wilderness setting," John Robison of the Idaho Conservation League said in a statement.

The Nez Perce Tribe in its objection contends the mining activities will harm stream habitat and salmon and steelhead runs, resulting in an infringement of fishing rights granted to the tribe in 1855 and 1859 treaties on lands that include the proposed gold mine.

"The Tribe has invested considerable time and resources in the Big Creek Watershed," the tribe wrote in its objection. "The potential for renewed mining activities such as the Project, however, pose the potential to undermine these accomplishments by negatively affecting the watershed and resources upon which the Tribe depends."

The Forest Service said mining is allowed in the wilderness as mining laws and mining in the area predates the wilderness designation, and the 2002 federal court ruling noted as much when it sided with the gold mining company. But the ruling also said the company had to focus only on work that's necessary to prove the claims profitable.

The conservation groups contend the work the Forest Service has approved goes beyond those limits.

The mining company itself filed an objection, mainly citing areas that needed clarification. One - involving bridges, culverts and pipes on a road into the wilderness - seeks to clarify that the structures should have sufficient strength for vehicles weighing up to 45 tons.

"This will ensure safe passage for equipment that may be needed for this or future projects without requiring further work or fording and the associated environmental impacts," the company wrote.

Brian Harris, Payette National Forest spokesman, said the Forest Service has 90 days from the March 17 close of the objection period to meet with those who have objected and find a solution.

If the process moves forward and the company proves the claims are profitable, the next step would be for the company to submit a plan on how it would go about mining. If the plan meets environmental requirements, the company could eventually start mining.

"It is allowable by law," Harris said. "So there is a chance that a full-production gold mine could take place within the wilderness area."