MINNEAPOLIS (AP) — Environmental groups are launching a campaign ahead of the summer vacation season against plans for copper, nickel and precious metals mining in northeastern Minnesota.

Conservation Minnesota, Friends of the Boundary Waters Wilderness and the Minnesota Center for Environmental Advocacy are targeting the proposed PolyMet and Twin Metals mines.

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The groups say the copper, nickel, gold and other metals are locked up in minerals that can produce sulfuric acid and other contaminants when exposed to the elements.

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Frank Ongaro of the industry group MiningMinnesota says the state has strong regulations to protect the environment and companies won’t get a permit unless they show they can meet them.

The campaign includes the web site MiningTruth.org, a 40-page report, and four billboards along Interstate 35 between Minneapolis and Duluth to reach summer travelers.

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