BISMARCK, N.D. — Environmental study of the Dakota Access oil pipeline is likely to continue into the summer as federal officials meet with American Indian tribes who have raised concerns about being left out of the process.

The U.S. Army Corps of Engineers plans to meet with all four tribes by the end of the month, Justice Department attorney Matthew Marinelli said in a status report to U.S. District Judge James Boasberg that was filed Wednesday.

Boasberg is overseeing a lawsuit filed in July 2016 by the Standing Rock, Cheyenne River, Yankton and Oglala Sioux tribes, who hope to shut down the $3.8 billion pipeline that began moving North Dakota oil to Illinois last summer. They fear environmental and cultural harm. Texas-based developer Energy Transfer Partners says the pipeline is safe.

Boasberg allowed oil to begin flowing last June despite lingering concerns about the pipeline's impact on tribal interests, including how a spill under the Missouri River in the Dakotas would impact tribal water supplies. He ordered more study on those topics.

The Standing Rock and Cheyenne River tribes earlier this year said they weren't being given a meaningful role in that process, and they asked Boasberg to order that they be given more involvement.

Boasberg last month rejected the request, saying the tribes can press their argument that the study is flawed when the work is completed and presented to him.

The Corps had anticipated an April 2 completion date, but that didn't materialize because of what the agency maintained was difficulties in obtaining needed information from the tribes.

Marinelli said the Corps received information from the Standing Rock Sioux in March and met with officials from that tribe late that month. The other three tribes all met an agency-set April 20 deadline for requested information, and the Corps is scheduled to meet with each tribe by June 1, he said.

Boasberg on Thursday gave the Corps until June 8 to set a date for completion of the work.