In a move that should keep the Dakota Access Pipeline (DAPL) in operation for the time being, the U.S. Court of Appeals for the D.C. Circuit has stayed part of an order issued last month that would have required the crude oil system to empty pending further environmental review.

However, in a decision filed Wednesday, the appeals court ruled against DAPL operator Energy Transfer LP by upholding the previous court’s decision to vacate the pipeline’s easement to cross Lake Oahe. The large reservoir is behind the Oahe Dam on the Missouri River that begins in central South Dakota and continues north into North Dakota.

“At this juncture, appellants have failed to make a strong showing of likely success on their claims that the district court erred in directing” the U.S....