The oil flow through Enbridge's pipelines across northern Minnesota has grown significantly since the company set out to build its new Line 3.

Honor the Earth, an Indigenous environmental group, in October asked for the state's utility regulators to investigate that change in volume, saying it negated the need for the $3 billion replacement for the existing Line 3.

The Public Utility Commission (PUC) on Thursday declined to investigate in a 5-0 vote. The commissioners agreed with Enbridge that the panel lacked jurisdiction because its approval of the Line 3 project is now in front of the Minnesota Court of Appeals.

"I don't want the court to somehow look at us as trying to interfere with its jurisdiction," said John Tuma, a PUC commissioner. "If we start monkeying around with the record, it could cause a delay at the Court of Appeals."

Paul Blackburn, an attorney for Honor the Earth, said the record for the appeal is already set and wouldn't be reopened just to account for the group's complaint about Enbridge.

Honor the Earth and other environmental groups, along with three Ojibwe bands, appealed the PUC's 2020 approval of Line 3. They said, among other things, that Enbridge's demand forecasts for the pipeline were faulty.

The Minnesota Department of Commerce also has appealed the PUC's Line 3 approval on the oil demand issue.

The appeals court held oral arguments on March 23. A decision, which could halt work on the pipeline, is due by June 21.

Oil volume on Enbridge's Minnesota system rose steadily in the late 2010s, climbing past an annual average of more than 2.8 million barrels per day as the company increased its operating efficiency. The new Line 3 would add about 375,000 barrels per day of capacity to Enbridge's corridor of six pipelines across Minnesota.

During the hearings for Line 3, Enbridge had reported that the system's effective capacity was just over 2.4 million barrels per day, meaning the company has added 400,000 barrels per day in capacity. Thus, Honor the Earth claims Enbridge provided incorrect information to the PUC during the Line 3 hearings.

Enbridge began building the new Line 3 in December after a six-year regulatory fight. The company said the new pipeline is a major safety improvement over the existing Line 3, which is corroding and operating at 51% capacity.

Opponents said the new Line 3 — which partly follows a new route — will open a new region of Minnesota lakes, rivers and wild rice waters to oil-spill degradation, as well as exacerbate climate change.

The pipeline is half-completed. Since April 1, Enbridge has been working only on pipeline pumping stations. Construction of the pipeline itself is slated to restart June 1 with the end of springtime road and environmental restrictions.

Mike Hughlett • 612-673-7003