ST. PAUL (WCCO) — The possibility of more precious metal mining proposals in northern Minnesota took another step forward on Friday after the state’s executive council approved 31 leases of state and private lands to three mining companies seeking exploration.

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The council, comprised of the governor, the lieutenant governor, the attorney general, the state auditor, and the secretary of state met for nearly an hour before voting to proceed with the leases of 9,500 acres in Lake, St. Louis and Aitkin counties. In a 4 -1 vote, the council approved granting the leases to three mining companies.

However, opponents of sulfide mining say their fight to stop it is only beginning. That’s because the land being leased is some of the most pristine and precious wilderness found anywhere in the United States. But underneath the treasured woods and waters are other treasures, like copper, nickel and gold.

State Auditor Rebecca Otto was the lone dissenter in granting approval.

“This kind of mining has not gone well anywhere it’s been done,” she said.

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Otto says she understands the promise of jobs and economic vitality that more mining could bring. But as an avid wilderness canoe paddler and a former science teacher, she also understands the long-term threats posed by acid leaching from mining operations.

“For me, as a statewide elected official and as a state auditor, I want to make sure that we’re thinking about the financial burden it could place on the next generations,” Otto said. “We have to have that in mind.”

She’s not alone in her apprehension. Environmental groups have tried unsuccessfully in court to stop the prospects of sulfide mining, saying it is far more dangerous than the iron ore mining that is so well known to Minnesotans. They fear sulfide mining will contaminate ground and surface waters when the acid from the extraction process leaches out.

They contend it has been proven to be dangerous in other states where it has been used, and they say containing the polluted waters could require expensive treatment for hundreds of years. Among those opposed to precious metal mining is the Friends of the Boundary Waters Wilderness, a group which promises a long fight ahead.

“Ultimately, these are all designed to develop a mine. So the question of what the environmental impact is of that eventual mine…is something, I think, to consider at the very beginning rather than at the very end,” said Aaron Klemz, the group’s communication director.

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Under Minnesota’s mineral laws, private landowners are required to allow exploration in lease areas. However, the council directed the DNR to notify landowners to allow them to request an environmental review of the exploration process.