A federal judge has overturned a decision by the U.S. Forest Service to allow oil and gas drilling near a forest and a river in Michigan's northern Lower Peninsula.

U.S. District Judge David Lawson of Detroit ruled Thursday the agency had acted "arbitrarily and capriciously" in 2005 by giving Savoy Energy LP of Traverse City a permit to drill an exploratory well near the Au Sable River's south branch.

The proposed wellhead would be located in the Huron-Manistee National Forest about three-tenths of a mile from the Mason Tract, a 4,679-acre wilderness area prized by anglers and other outdoor recreationists.

Forest supervisor Leanne Marten said when approving Savoy's application that the project wouldn't significantly harm the environment and the company would be required to keep noise to a minimum.

But the judge ruled the Forest Service didn't consider how degrading the area could harm tourism, and said the agency did a "woefully inadequate" job of evaluating how the drilling might affect the Kirtland's warbler, an endangered songbird that nests in the area.

Two environmental groups, the Sierra Club and Anglers of the Au Sable, sued the government to halt the drilling. Joining the suit was Tim Mason, whose grandfather, auto executive George Mason, donated the original 1,200 acres to the state upon his death in 1954 and asked that it be maintained as wilderness.

"The ruling supports what my grandfather's vision was. It's a victory," said Mason, a Woodstock, Ill., businessman.

Huron-Manistee spokesman Ken Arbogast referred a request for comment to the U.S. Department of Justice, which represented the Forest Service in court. Andrew Ames, a spokesman for the department, said its attorneys were studying Lawson's ruling and had not decided whether to appeal.

A message seeking comment was left with Savoy.

Leaders of the environmental groups urged the company and the government to look for other places to explore for oil and gas.

"We've said from the beginning we didn't want to stop them from drilling," said Marvin Roberson, a forest policy specialist with the Sierra Club. "We want them to drill from a place that won't be harmful to the old-growth forest or the recreational experience."

Although the Mason Tract is state property, the federal government owns rights to minerals beneath it and leased production rights to Savoy. In 2003, the company filed for a permit to drill into one of its lease holdings.

The plan was to clear about 3.5 acres of forest for a well site on federal land, then drill beneath the Mason Tract at an angle. If enough gas or oil was found, the company intended to install a pipeline and build a production facility about a mile east of the well.

The U.S. Bureau of Land Management approved the project shortly after the Forest Service granted the permit. But it has been on hold since Lawson issued an order in December 2005 blocking the company from clearing land to get started.