An all-Republican board of government regulators in North Dakota voted to approve a permit that would expand the capacity for the Dakota Access pipeline project, which they believe has met rigorous state and federal requirements to proceed but that opponents say still presents concerning risks for the environment and for constituents living in the region.

The Public Service Commission alluded to its decision last month, and the vote Wednesday was 3-0.

Commissioners said they expect their decision to be challenged in state court, but Commissioner Julie Fedorchak said she welcomed such a review.

“I have no doubt issues are being addressed,” she said.

KEYSTONE PIPELINE LEAK SPILLS MORE THAN 380,000 GALLONS OF OIL IN NORTH DAKOTA

Energy Transfer is the Texas-based company behind the Dakota Access pipeline, which has been moving oil from North Dakota through South Dakota and Iowa to a shipping point in Illinois since June 2017.

Energy Transfer proposed doubling the capacity of the pipeline last year to meet growing demand for oil shipments from North Dakota, without the need for additional pipelines or rail shipments.

The company plans to build a $40 million pump station near Linton in south-central North Dakota. The new station is necessary to increase the volume of oil the pipeline can move.

The company also plans to introduce additional pumping stations in South Dakota, Iowa and Illinois, but the project has faced an uphill battle for permit approvals, as protests and arrests presented hurdles to construction efforts.

The $3.8 billion pipeline which runs 1,172-mile underground crosses beneath the Missouri River, just north of the Standing Rock Sioux Reservation. The tribe pushed back on the pipeline fearing that it would pollute the river that they draw water from. Energy Transfer had insisted the pipeline would be safe and said the expansion would be, too.

Commissioner Brian Kroshus said Wednesday that he believes the project would help take oil trucks off the road, reducing traffic fatalities.

Since some of the land in North Dakota falls outside of the pipeline corridor, permission was needed from the commission to build the pump station. In addition, commissioners in a South Dakota county last year approved a conditional use permit to continue the project, while permits in other applicable states are still pending.

In Iowa, regulators want the company to provide expert analysis to back up the company’s assertion that doubling the line’s capacity won't increase the likelihood of a spill.

Energy Transfer said in court filings that its pump station would produce only "minimal adverse effects on the environment and the citizens of North Dakota," adding that they hope to start construction in the spring and finish within 10 months.

Opponents argued the commission should have considered effects all along the line and not solely at the pump station location.

“Today's decision demonstrates little to no consideration” to possible impacts of a spill or leak from the expanded pipeline, the tribe said in a statement after the vote. Tim Purdon, an attorney for the Standing Rock Sioux, said before Wednesday's vote that the tribe would review its legal options if the commission approved the project.

Allyson Two Bears, the tribe's director of environmental regulations, said she was “very, very disappointed” but not surprised by the commission's action.

“I see this as doubling our risk,” she said in an interview.

Commissioners agreed with Energy Transfer's argument that they could consider a permit application only for the pump site. Commissioners said the state would not impose conditions beyond those required by the federal government, which has jurisdiction on the pipeline.

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The Associated Press contributed to this report.