This is an archived article that was published on sltrib.com in 2017, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.

Bismarck, N.D. • Two Democratic U.S. senators want the chief of the Army Corps of Engineers to explain the agency's decision-making that ultimately paved the way for completion of the disputed Dakota Access oil pipeline.

Delaware Sen. Tom Carper and Washington Sen. Maria Cantwell are ranking Democratic members on Senate environment and energy committees. They sent a letter to Corps Lt. Gen. Todd Semonite Monday asking for a host of information including communications between the agency and Trump administration officials.

President Donald Trump pushed for the pipeline's completion shortly after taking office in January, despite the desire of American Indian tribes that wanted more environmental study.

Texas-based Energy Transfer Partners last month finished building the $3.8 billion pipeline, which should be fully operational later this month and moving North Dakota oil to Illinois.