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The Keystone XL pipeline cleared a major hurdle on Monday after a Nebraska regulator approved an alternate route for the $8 billion project.

The Nebraska Public Service Commission voted to approve TransCanada Corp.’s Keystone XL pipeline in a 3-2 decision that cleared a regulatory hurdle for the proposed 1,179-mile pipeline that would link Canada's Alberta oil sands to U.S. refineries.

A TransCanada Keystone Pipeline pump station operates outside Steele City, Nebraska March 10, 2014. Lane Hickenbottom / Reuters file

Nebraska was the only state that had yet to approve the pipeline's route, and Monday's decision appeared to pass that final regulatory challenge. But the move could still be challenged in court.

The five-member commission rejected TransCanada's preferred route and opted for one of the alternative routes that moves the pipeline farther east.

The landowners who are in the way of the approved pipeline now need to be contacted in order for the project to move forward.

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One commissioner, Crystal Rhoades, explained she voted “no” for six reasons, the first being “the route violates the due process of landowners. There are at least 40 landowners along the approved route who may not even know that their land is in this pipeline’s path. Since they might not know that they are in the path of the pipeline, they may not have participated in this proceeding.”

Opponents told The Associated Press following the decision that another federal review may be needed because the newly-approved route runs farther north than the original path.

“This decision opens up a whole new bag of issues that we can raise,” said Ken Winston, an attorney representing environmental groups that have long opposed the project.

TransCanada said in a statement that it was evaluating the commission's decision.

"As a result of today's decision, we will conduct a careful review of the Public Service Commission's ruling while assessing how the decision would impact the cost and schedule of the project," Russ Girling, TransCanada's president and chief executive officer, said in the statement.

The proposed Keystone XL would expand the existing Keystone pipeline, which went into service in July 2010. The current pipeline network runs south through North Dakota, South Dakota, Nebraska, Kansas, Oklahoma and Texas and extends east into Missouri and Illinois.

Monday's decision comes days after part of the existing controversial pipeline spilled more than 200,000 gallons of oil in South Dakota. TransCanada Corp. said in a statement Friday that the incident was "controlled" and that there was no risk to public safety.

On Sunday, the company said that "work continues to progress at the Amherst incident site. There are now approximately 150 people on-site, working around-the-clock, on clean-up and remediation activities." The leak was first reported Thursday.

The commission was not permitted to consider pipeline safety considerations or spill risks in its decision under Nebraska law.

The project was rejected by President Barack Obama in 2015 over environmental concerns, but in January President Donald Trump signed a series of executive orders that advanced both the Keystone XL and Dakota Access pipelines. The project has long been opposed by environmental groups, some landowners and Native American tribes.

Trump then announced the federal government's approval of the Keystone XL pipeline in March, pledging that its construction would bring new jobs.

Opponents of the project have vowed legal action and protests if it were approved.