A handful of environmental groups have asked the state Court of Appeals to reject permits granted for Minnesota's first copper-nickel mine, a proposal by PolyMet Mining Corp., and, in a separate legal filing, are challenging the underlying state rules that govern environmental hazards posed by that type of mining.

The filings are the latest in a series of appeals the groups have made questioning the state's environmental review of PolyMet's controversial project on Minnesota's Iron Range. But this is the first time they have taken legal action against the state's as-yet untested environmental rules governing copper-nickel mining.

In legal challenges filed Monday, the groups said the Minnesota Department of Natural Resources (DNR) has not done all it can to protect people downstream from the mine against water pollution. Their filing notes that the agency rejected more stringent alternatives for managing mine waste; dismissed concerns raised by some of its own consultants about the safety of a tailings dam for mine waste; and approved a plan that relies on a water treatment facility that would have to operate indefinitely to prevent long-term pollution.

"There is a myth in Minnesota that we have tough regulators," said Paula Maccabee, advocacy director and counsel for WaterLegacy, one of the nonprofits joining Monday's legal action. "It's just the opposite. "

DNR officials defended the PolyMet permits as products of more than a decade of thorough environmental review and 80,000 public comments.

"We are confident that the permit decisions we made … are based on sound science, provide strong protections for Minnesota taxpayers and are fully consistent with state law," said Barb Naramore, assistant DNR commissioner.

PolyMet, a Toronto-based publicly held company, declined to comment.

A pro-mining group that represents unions and business interests in northeastern Minnesota said the mining project deserves to move forward without delay. "This appeal is one more attempt to delay a critical project for the state of Minnesota that has demonstrated it can meet or exceed regulatory standards," it said in a statement.

In their challenge to Minnesota's copper-nickel mining regulations, the groups say they fail to set adequate standards for operational designs specified in state permits and for the reclamation of land after mining stops. That gives the DNR too much authority over mining without adequate public review, they said.

In previous filings, the groups have also asked the appeals court to require an expanded environmental review to address recent filings by PolyMet for the project, and to order an independent review of the DNR's permit decisions by an administrative judge.

The other groups that signed onto the filings are the Minnesota Center for Environmental Advocacy; Friends of the Boundary Waters Wilderness; the Center for Biological Diversity; Duluth for Clean Water; Save Lake Superior Association; Friends of the Cloquet Valley State Forest; and Save Our Sky Blue Waters.