Chicago, US: Construction has begun on the final segment of the controversial Dakota Access oil pipeline in the northern United States, prompting a court challenge from a Native American tribe which says its religious rights are under threat.

Energy Transfer Partners, the developer of the 1,172-mile (1,886-kilometer) oil pipeline, now expects to begin operation ‘in approximately 83 days,’ spokeswoman Vicky Granado told AFP on Thursday.

The segment’s route under the Missouri River and man-made Lake Oahe in North Dakota was the subject of months of protests, as Native Americans and their supporters argued it ran the risk of potentially polluting the water.

The Cheyenne River Sioux tribe, whose reservation is near the waterway, asked a federal judge to issue a temporary restraining order halting construction on the grounds that the pipeline would harm its ability to perform religious rites.

‘The pipeline will desecrate the waters upon which Cheyenne River Sioux tribal members rely for their most important religious practices,’ the court filing said.

‘And in view of the threat to the tribe’s and its members’ constitutional right, this court may not wait until the oil is slithering under the Tribe’s sacred waters. The law entitles the Tribe to relief as soon as the government acts to threaten their rights.’

The Cheyenne River Sioux want work stopped while its lawsuit filed jointly with the Standing Rock Sioux tribe proceeds through the courts.

The US Army Corps of Engineers—having approval authority over the pipeline’s underwater route—cleared the way on Tuesday for the project to be completed.

Under the administration of Trump’s predecessor Barack Obama, the Corps had called for further review and halted construction. But President Donald Trump ordered officials to reconsider. 

Protesters began camping out near the pipeline’s river crossing starting in April last year, in order to physically prevent construction, at times violently clashing with authorities and pipeline company workers.

The company has claimed the project is safe, and that there are already other pipelines operating safely under the disputed waterway. 

US District Court Judge James Boasberg was expected to set a court hearing to consider arguments on the Cheyenne River Sioux’s motion.