The US Army Corps said in a court filing it has notified Congress that it has granted the final easement needed to finish the controversial Dakota Access pipeline. The easement was needed for Energy Transfer Partners to complete work on the last pipeline portion located under Lake Oahe.

Stmt from US Army says they intend to grant the easement needed to complete the #DakotaAccessPipeline: pic.twitter.com/NgLyIzMXww — Frank Thorp V (@frankthorp) February 7, 2017

The 1,172-mile line will bring crude oil from North Dakota's Bakken shale region to Patoka, Illinois, and from there connect to the Gulf of Mexico, where many U.S. refineries are located.

The Standing Rock Sioux tribe, whose reservation is adjacent to the line's route, has said they will fight the decision. The Army Corps had previously stated that they would undertake further environmental review of the project. The tribe had fought the line for months, fearing contamination of their drinking water and damage to sacred sites on their land.

Their protests, along with those of climate activists, resulted in the Obama administration's decision to delay a final permit that would allow construction under the Missouri River. President Donald Trump, days after being sworn in, issued an executive order directing the U.S. Army Corps to smooth the path to finishing the line. Tuesday's filing was made in U.S. District Court in Washington D.C.

Last Friday, Bloomberg reported that the $3.8 billion Dakota Access oil pipeline may start operating June 1, assuming no new obstacles prevent it, according to a person familiar with the matter. It added that Energy Transfer Partners, the developer of the pipeline, will begin filling it with oil around Feb. 15, barring complaints or legal action to stop it, said the person.

Energy Transfer had previously said the project would be in service in the first quarter, which was delayed from its original projection of the fourth quarter of 2016. Vicki Granado, a spokeswoman for Energy Transfer, didn’t immediately respond to request for comment.

On Friday, Phillips 66, a stakeholder in Dakota Access, said the project is expected to be operational in the second quarter. The pipeline is more than 95 percent complete, and the timing guidance is pending issuance of the final easement needed from the Army Corps, Phillips 66 said in a statement. The oil refiner has a 25 percent stake in joint ventures to develop Dakota Access and the Energy Transfer Crude Oil Pipeline projects. The line started receiving shipments at two North Dakota terminals in January, a person familiar with the pipeline’s operations said last month.

Sunoco Logistics Partners is also a partner in the project. Marathon Petroleum Corp. and Enbridge Energy Partners announced a venture in August that would also take a minority stake in the pipeline.

The roll out is not expected to be without incidents, however, as environmentalists and nature groups have vowed to prevent the construction at all costs, suggesting that a showdown between Trump and the those who seek to halt the DAPL is imminent.