The Minnesota Supreme Court has rejected an appeal by opponents regarding the environmental impact statement (EIS) for Enbridge's proposed $2.9 billion pipeline — setting the stage for state utility regulators to fix the flawed document.

While the high court's decision restarts an oft-stalled process, it could still take several months before Enbridge gains the go-ahead for its controversial plan to replace the aging and corroding Line 3 across northern Minnesota.

In June, the Minnesota Court of Appeals shot down utility regulators' approval of the environmental impact statement (EIS) for the project, putting the long-delayed project in further limbo.

The appeals court sided with pipeline opponents on a key part of their complaint about the EIS: that the study didn't properly address the effects of a potential oil spill in the Lake Superior watershed. However, the appellate court rejected other arguments by Line 3 opponents against the adequacy of the EIS.

Honor the Earth and the Mille Lacs, White Earth and Red Lake Ojibwe bands then petitioned the Supreme Court to take up the other arguments. The Supreme Court, which hears fewer than 15% of the petitions it receives, issued its denial of the Line 3 request Tuesday.

"We are profoundly disappointed that the Minnesota Supreme Court felt more interested in siding with the rights of a Canadian corporation to proceed with a high-risk project than protecting the rights of the Minnesota Anishinabe and indigenous people and the rights of nature," Winona LaDuke, head of Honor the Earth, said in a statement.

The Minnesota Public Utilities Commission (PUC), which was waiting on the high court's decision, said Tuesday that it would now take up the EIS "as soon as possible."

Enbridge said in a statement it was "confident the [PUC] will soon provide guidance on the remaining process and schedule." The Minnesota Department of Commerce conducted the EIS, and is expected to be told by the PUC how to fix it so it complies with the appellate court ruling.

Calgary, Alberta-based Enbridge has been on a five-year quest to build a new 330-mile pipeline to replace its current Line 3. The 1960s-vintage pipeline runs at only 51% of capacity due to safety concerns. Enbridge said a new pipeline will greatly improve safety and restore the full flow of oil.

Environmental groups and Ojibwe bands said it will add to global warming and open a new region of Minnesota's waters to degradation from oil spills. The new Line 3 would partly follow a new route through some prime lake country, instead of running wholly along Enbridge's current corridor of six pipelines.

The PUC ruled in March 2018 that Enbridge's EIS was "adequate," and approved the pipeline — granting a "certificate of need" — about 10 weeks later. Enbridge originally hoped to get its remaining state and federal permits for Line 3 by the end of 2018, with construction completed sometime this fall.

Mike Hughlett • 612-673-7003