An Indigenous-led environmental group said Enbridge's proposed Line 3 oil pipeline across northern Minnesota is no longer needed, since the company is adding capacity to its network of existing pipelines.

In filings Tuesday, Honor the Earth asked the Minnesota Public Utilities Commission to investigate increases in oil moved along the mainline system over the last four years totaling 400,000 additional barrels of oil and the company's proposed upgrades at its Superior terminal that would boost Lines 4 and 67 — both part of the mainline — by 178,400 barrels per of oil per day.

Enbridge is seeking to replace its existing, aging Line 3 with a new 340-mile pipeline through northern Minnesota capable of carrying 760,000 barrels of oil (double the current flow of the existing Line 3) from Alberta, Canada, to its terminal in Superior. Segments in Canada, North Dakota and Wisconsin are already complete.

The group argued since combined increases would exceed new capacity created by the new Line 3, the project is no longer needed.

"Together, Enbridge’s completed and proposed efficiency-based expansions provide far more crude oil import capacity than the 370,000 (barrels per day) of new capacity that would be created if the proposed new Line 3 pipeline is constructed," Honor the Earth said in a news release.

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The group also said Enbridge should seek recertification, which is required for capacity increases of 10% or more, and that the increases were kept out of state's now six-year review of Line 3, which the company disputed.

"Honor the Earth consistently argued that Enbridge could transport more oil than the proposed new Line 3 pipeline by simply using its existing pipelines more efficiently, thereby making a new Line 3 pipeline unnecessary. Now, Enbridge’s own data and statements prove that Honor the Earth’s arguments were correct," Honor the Earth said.

But Juli Kellner, an Enbridge spokesperson, said the company has been "transparent" in the Line 3 review process and has "previously indicated various optimizations," like bringing the Canadian portion of Line 3 into service.

"The permit for the Superior Terminal reflects current and future crude oil volumes through the terminal; including increased volumes from a replaced Line 3," Kellner said. "It should be noted those volumes fluctuate based on our customers’ needs."

The new $2.6 billion Line 3 would mostly follow the existing mainline but take a new route through much of Minnesota and has been working through the approval process since 2014.

The PUC has twice granted the project a certificate of need and route permit, but the project still requires several permits and must move through the court system.

The Minnesota Pollution Control Agency has until Nov. 14 to issue a decision on the pipeline's 401 certification, a permit awarded by a state's regulators if the project's impact on water falls within the state's standard, before it's passed on to the U.S. Army Corps of Engineers for the water permit's final approval.

An administrative law judge earlier this month said a coalition of environmental and tribal groups could not prove the pipeline's construction would harm wetlands and streams and urged the MPCA commissioner to make the same determination.

In addition to permitting from the MPCA and Army Corps, the project must navigate other hurdles before construction can begin on the Minnesota segment, including an appeal by Gov. Tim Walz's administration that argues the PUC relied on the wrong demand forecast when considering if the state needed the pipeline.