The permits, under review, would affect 44,000 acres of national forest.
On the hunt for copper and other valuable metals, five exploration companies hope to prospect on 44,000 acres of the Superior National Forest near the Boundary Waters Canoe Area over the next two decades.
The details of their plans are described in a draft environmental review released last week by the U.S. Forest Service, which is seeking public comments on it.
If ore is discovered, it could bring new mining projects to the national forest -- a prospect that worries environmentalists and has been cheered by economic development officials in northern Minnesota.
The exploration is driven by high metal prices and hopes of finding copper, nickel, platinum and other ores in the heart of a geological formation called the Duluth Complex in Minnesota's Arrowhead region. If all 44,000 acres are explored, it would represent more than double the area previously prospected in the formation, industry officials said.
"Very little of the Duluth Complex has been explored," said geologist Ernest Lehmann, whose company is among five planning to look deeper into the formation using core-drilling rigs and other techniques.
For decades, geologists have been finding copper and other metals south of Babbitt and Ely, Minn., on the edge of the complex. That's where PolyMet Mining Corp. is proposing an open-pit mine, and Twin Metals LLC is considering an underground mine. Past exploration for metals in the interior of the formation hasn't been fruitful, Lehmann said.
"That doesn't mean it isn't there," said Lehmann, who estimated the odds of finding mineable ore at 100 to 1, which he considers good.
Geologists are armed with better data about the complex, said Dean Peterson, senior vice president for exploration at Duluth Metals Ltd., which is seeking permits to prospect on 16,500 acres of the forest.
"We have better chances than in the past, but it is still a high-risk business," he said.
Encampment Resources, based in Atlanta, wants to prospect on 18,100 acres of the forest. Twin Metals, a joint venture with Duluth Metals, is interested in 5,700 acres, and Prime Meridian of Calgary, Alberta, has applied to explore 720 acres. Lehmann Exploration applied for 3,140 acres.
All have waited five years for Superior National Forest to complete its first environmental study of prospecting. It found no major problems, and estimated that prospecting would temporarily disturb about 186 acres a year. Drilling rigs would need up to 860 miles of temporary roads over 20 years, and drill noise could reach some BWCA campers, the study found.
Environmental groups say mining in sulfide ores poses a pollution risk to waters leading to Lake Superior and the BWCA, a subject not included in the prospecting review.
"It is by far the biggest environmental concern in the state right now," said Marc Fink, a Duluth attorney who pressed the Superior National Forest to conduct the prospecting review while on the staff of the nonprofit Forest Service Employees for Environmental Ethics. He now works for the Center for Biological Diversity, which has challenged the PolyMet project.
Industry officials say prospecting has gone on in the region for 60 years without damaging the forest. Each drill site must be separately approved by the forest service, and roads must be blocked off with downed trees after drills pull out. If a mine eventually is proposed, the project would be studied extensively.
Bill Travis, president of Idea Drilling of Virginia, Minn., said the company's 14 core-drilling rigs already are "basically running at 100 percent capacity" at other explorations in the region. The company has ordered three more rigs, which are quieter than older models, and plans to buy more, he said. Employment is up 50 percent to 100 workers, he added.
Companies that find ore under prospecting permits are not guaranteed a mining lease.
"We have a decision in the future, which is kind of a risk on the companies' part," said Loretta Cartner, a Forest Service geologist who headed the study. "They are spending all this money on exploration, but they are not guaranteed they can move to a lease."
Cartner said the environmental study should be completed by the end of the year. Permits could be issued after that, unless the agency's actions are appealed or challenged in court, she said.
David Shaffer • 612-673-7090