The Environmental Protection Agency says the proposed Polymet copper-nickel mine proposed for northeastern Minnesota should not go ahead as currently planned.
The EPA listed more than two-dozen so-called inadequacies in the Minnesota Department of Natural Resources' draft environmental impact statement, or EIS.
The DNR's Steve Colvin says the criticisms come in part because of a difference in approach by the two levels of government.
"In the federal process, you're expecting the information in the EIS to be more detailed, very close to what you need to make a permit decision, whereas in the state process you're not at that permitting level of detail," Colvin said.
The EPA warned of possible impacts to water quality and wetlands, increased emissions of mercury into the Lake Superior watershed, and what it called "inadequate financial assurance for performance."
Attorney Paula Maccabee says the EPA document validates concerns expressed by her group, Water Legacy, and others.
"The way it's proposed now does not adequately protect the environment, and the current draft environmental impact statement doesn't adequately disclose the nature of the environmental impacts this projects may have," Maccabee said.
The DNR says it's reviewing the EPA's criticisms of the project and will take several months to respond to the comments.