Dakota Access oil pipeline's operators plan to ask the U.S. Supreme Court to intervene in its ongoing legal battle to keep the 570,000 barrel-per-day line open, according to a court filing on Thursday.
 
The operators of the line, led by Energy Transfer LP, sought a stay from the U.S. Court of Appeals for the District of Columbia, saying it would allow the Dakota Access Pipeline (DAPL) to continue operating.
 
Unless the Supreme Court acts in its favor, the 1,886-km Dakota Access Pipeline (DAPL) is dead in the water, as a U.S. Appeals Court this past weekend has denied DAPL's petition for a rehearing on a court decision to cancel a key permit for its oil pipeline.

The 570,000 barrel per day pipeline began operating in mid - 2017 but quickly became controversial during construction as Native American tribes protested its route under Lake Oahe, an important source of drinking water for the tribe.

Last summer, a U.S. district court judge threw out a federal permit for the line to operate under the lake and ordered an environmental review for that section of the pipeline. A three-judge panel at the circuit court in January upheld the lower court's decision to vacate the permit and require the review.

A spokeswoman for Energy Transfer LP, DAPL's majority owner, declined to comment on current or pending legal matters.