Minnesota utility regulators will try to fix their flawed environmental review of Enbridge's proposed $2.6 billion oil pipeline rather than take the issue to the Minnesota Supreme Court.

The Minnesota Public Utilities Commission said Wednesday it won't petition the high court to overrule a June 3 decision by the Minnesota Court of Appeals.

The appeals court shot down the PUC's approval of the environmental impact statement (EIS) for Enbridge's controversial and much-delayed project, which would replace the current aging Line 3. The court deemed the EIS "inadequate," saying it didn't properly address the effect of an oil spill in the Lake Superior watershed.

Wednesday was the deadline for the PUC, Enbridge or any other party to appeal the appellate court's decision directly to the Supreme Court. Calgary, Alberta-based Enbridge also has not asked for a Supreme Court review.

At this point, it appears that a successful Supreme Court appeal could actually take longer than any PUC attempt to fix the EIS.

"The [PUC] has concluded the public interest will be best served by addressing the deficiency identified in the Court of Appeals decision rather than appealing to the Minnesota Supreme Court," Katie Sieben, the PUC's chairwoman, said in a statement.

She said the PUC will seek public comment and "work expeditiously" to address the issue. However, she offered no timeline, and the PUC declined to comment beyond the statement.

The PUC voted 5-0 in March 2018 to approve the EIS, and unanimously approved a "certificate of need" for the pipeline — its most critical permit — in late June 2018. Environmental groups and some Ojibwe tribes have appealed both decisions.

Because the EIS is up in the air, last week the appeals court ruled that it would stay the appeal of Enbridge's certificate of need.

When Enbridge won the certificate of need a year ago, it had planned to be building the pipeline now with a projected opening date later this year. But delays in other state permits caused Enbridge in March to announce that Line 3 wouldn't open until sometime in 2020. The recent appellate court decision put the project further in limbo.

Pipeline opponents argue that new pipeline will enable global warming and open a new region of Minnesota's lakes, rivers and wild rice waters to environmental degradations from possible oil spills.

Enbridge and pipeline proponents said the new pipeline is needed because the current Line 3, which runs across northern Minnesota, is corroding and needs constant repairs. The 1960s vintage pipeline operates at about half capacity due to safety concerns; Enbridge would restore the full flow of oil with a new pipeline.

The appellate court, while faulting Lake Superior watershed modeling in the EIS, rejected several other arguments against the validity of the EIS. So, pipeline opponents Wednesday petitioned the Supreme Court to overturn parts of the appellate court's order that affirmed the EIS.

The petitioners are the indigenous environmental advocacy group Honor the Earth and three Ojibwe bands: Mille Lacs, White Earth and Red Lake. The Supreme Court hears less than 15% of the petitions it receives.

Redoing even a small part of the voluminous EIS — such as the Lake Superior oil-spill projections — could take months, raising questions about more delays for Enbridge. But a Supreme Court resolution of any part of the appellate court decision could take until next year.

The PUC has been silent on Line 3 over the past month. Recently, several pipeline supporters — including the Minnesota Chamber of Commerce and 45 Republican legislators — filed comments with the commission, urging it to quickly fix the EIS to minimize further delays for Enbridge.

The EIS was done at the behest of the PUC by the Minnesota Department of Commerce, but the PUC must order any remedy ordered by the court. "We are hopeful the PUC will meet soon to provide direction to the Department of Commerce on the process to revise the EIS," Enbridge said in a statement.