ST. PAUL, Minn. (AP) — Environmental advocates are calling on Gov. Mark Dayton to require stronger environmental protections for a proposed copper-nickel mine in northeastern Minnesota.

Aaron Klemz from the Friends of the Boundary Waters Wilderness says the latest environmental review of the PolyMet highlight concerns of water pollution. His group announced a statewide ad campaign Monday urging the Democratic governor to intervene.

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The Department of Natural Resources released its latest review last week. The entire process won’t conclude until at least next year.

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Opponents’ concerns revolve around a 2014 spill of a mining waste storage pond in Canada. Klemz says Dayton should require that PolyMet use a different storage design.

Dayton’s spokesman Matt Swenson says the governor will wait to weigh in until all reviews and analyses have been completed.

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