The Army has started the process of launching a full environmental study of the $3.8 billion Dakota Access pipeline's disputed crossing of the Missouri River in North Dakota, though a federal judge could stop the effort.

The Army published a notice Wednesday of its intent to prepare an environmental impact statement on the Lake Oahe crossing. Texas-based developer Energy Transfer Partners won't be able to lay pipe under the reservoir while the study is ongoing — it is currently blocked from doing so anyway. A study could take up to two years, according to the Energy Department.

ETP asked U.S. District Judge James Boasberg on Tuesday to block the study; he scheduled a hearing for Wednesday afternoon in Washington, D.C.

ETP wants Boasberg to rule on whether the company already has the necessary federal permissions to finish the pipeline under Lake Oahe, the water source for the Standing Rock Sioux tribe. The tribe and its supporters believe the four-state pipeline threatens drinking water and cultural sites. ETP disputes that and says the pipeline will be safe.


dakota pipeline

A section of the Dakota Access Pipeline under construction in Morton County, N.D. (AP)

The stretch under Lake Oahe is the last big chunk of construction for the 1,200-mile pipeline. ETP has said in court documents there is already oil in a portion of the pipeline leading up to the lake in anticipation of finishing the project. But the Corps wants to look at alternate routes, the potential for a pipeline leak and tribal treaty rights in the wake of opposition by Standing Rock.

The Army's Federal Register notice says it is accepting public comments until Feb. 20 on "potential issues, concerns and reasonable alternatives" that should be considered in a study.

ETP said the Corps gave it permission in July to proceed with the Lake Oahe stretch, but the Corps says all of the necessary steps have not yet been completed — including an easement to work on federal land and the notification of Congress.

An environmental assessment conducted last year determined the crossing would not have a significant impact on the environment. However, Assistant Army Secretary for Civil Works Jo-Ellen Darcy said in December that a broader environmental impact statement was warranted.


North Dakota U.S. Sen. Heidi Heitkamp told The Associated Press that she thinks the federal government is "changing the rules in the middle of the process" and that she expects the judge to block the study.

The Standing Rock Sioux had urged people to lobby the Corps to start the study before President-elect Donald Trump takes office Friday. Trump, whose transition team said in a memo that he supports the pipeline's completion, could seek to reverse the Army's decision last month to not allow the river crossing.

Opponents have camped near the pipeline route in North Dakota since the summer. The number of arrests surpassed 600 this week, as 16 were arrested Monday and Tuesday in confrontations near the camp.