The state environmental review of Enbridge’s controversial new oil pipeline across northern Minnesota was rejected by utility regulators Thursday, though only on a few narrow concerns.

The Minnesota Public Utilities Commission, by a vote of 4 to 1, deemed “inadequate” the Environmental Impact Statement (EIS) for Enbridge’s proposed new Line 3 pipeline.

The EIS, conducted by the Minnesota Department of Commerce, looked at myriad potential environmental outcomes of a new pipeline but made no conclusions.

The PUC essentially told the Commerce Department to rejigger three relatively small parts of the doorstop-sized EIS, and do so within 60 days. The PUC was reacting to criticisms of the EIS by Indian bands and environmental groups.

“I am not looking to make a finding that the EIS is generally inadequate,” said Dan Lipschultz, a PUC commissioner. “The EIS is quantitative, robust and detailed.” But it needs to be “supplemented,” he said.

PUC approval of the pipeline EIS is necessary for the project to move forward. However, the EIS is just one piece of the approval process.

The PUC won’t decide until at least April whether the new 340-mile Line 3 is warranted, and if so, what exact route it would take.

Environmental groups and Indian tribes that oppose the pipeline have criticized the EIS on several fronts, including for the lack of a detailed assessment of a potential large oil spill into sensitive waters and wilderness areas.

The new pipeline would shuttle oil from Canada to Enbridge’s terminal in Superior, Wis., and replace Enbridge’s current Line 3. Calgary-based Enbridge says the $2.6 billion pipeline is a necessary upgrade: The 1960s-vintage Line 3 operates at 51 percent of its 390,000 barrel-per-day capacity due to safety concerns. The new Line 3 would restore full capacity.

Opponents of a new Line 3 say the pipeline would expose a new region of Minnesota — including pristine lakes and wild rice waters — to degradation from oil spills.

Enbridge’s proposed new route would follow the current Line 3’s path to Clearbrook, Minn., but then jog south toward Park Rapids before heading east to Superior.

The current Line 3, along with five other Enbridge pipelines, runs roughly parallel to U.S. Hwy. 2 from Clearbrook to Superior.

Specifically, the PUC asked the Commerce Department to provide more information on whether one particular alternative to Enbridge’s proposed route could be tweaked to avoid sensitive geologic formations.

The PUC also asked the Commerce Department for more clarity on how it weighted certain environmental outcomes in its review of five Line 3 alternative routes. It’s not clear how many EIS calculations that would affect.

Also, the PUC said the Commerce Department needed to do a better job identifying the impacts of two alternative routes that roughly parallel Enbridge’s current Line 3.

It’s not always clear in the EIS whether a new Line 3 on the current route would create new environmental problems or whether those problems already exist.

Representatives of the Fond du Lac Band of Chippewa and Mille Lacs Band of Ojibwe both told the PUC that the EIS was inadequate because it lacked a formal tribal cultural resource study.

Environmental impact statements often account for such cultural resources as burial grounds, which can be unearthed when pipelines are built.

Commerce Department officials agreed that such a cultural study should be done, but said it’s not their job. The U.S. Army Corps of Engineers and Minnesota’s historical preservation office are supposed to do that survey in conjunction with the tribes.

The tribal cultural survey is underway, but tribal representatives said it won’t be finished until sometime in 2018.

“We have a problem,” Lipschultz said. “We have a survey that is not and cannot be done in the time frame we are looking at.”

So the PUC also voted that construction can’t start on a new Line 3 — if it is approved — until a tribal cultural survey is completed. Plus, the PUC said it would weigh any information from the cultural study that it could obtain before its final vote on Line 3.

However, attorneys for tribal interests argued that the PUC, if it approves Line 3, would be doing so without complete information on cultural impacts.

“Once again, Native American interests have slipped through the cracks,” said Paul Blackburn, an attorney for Honor the Earth, an Indian-led environmental activist organization.

“Guess what? Maybe we will have some partial information in the record.”