Two groups filed court documents Wednesday arguing the state's environmental review of Enbridge Energy's Line 3 oil pipeline was insufficient.
Honor the Earth and Friends of the Headwaters claim the environmental impact statement, or EIS, failed to look at potential oil spills at specific locations or the results of a tribal cultural survey.
In June, the five-member Minnesota Public Utilities Commission unanimously granted the 340-mile long pipeline across Minnesota a certificate of need, but deemed the EIS "adequate" in March.
In a statement Wednesday, Richard Smith, president of the Friends of the Headwaters, said the PUC was in the wrong.
"We don't think the final EIS was conducted in accord with environmental law and feel an obligation to challenge the Public Utilities Commission's adequacy ruling," Smith said.
In a separate statement, Winona LaDuke, executive director of Honor the Earth, said the EIS overlooked many factors.
"The FEIS was the most extensive, related to a pipeline project, in the history of Minnesota," Smith said.
Though the company maintains the new pipeline is needed to replace the existing and aging Line 3, opponents contend the line contributes to climate change, violates indigenous rights and is ultimately unnecessary.