The federal agency, Texas-based pipeline developer Energy Transfer Partners and energy trade groups also are advocating for keeping the line operating during the study.
The $3.8 billion North Dakota-to-Illinois pipeline that's opposed by American Indian tribes has been operating since June 1. But U.S. District Judge James Boasberg last month ordered the Corps to do more study on its impact on the Standing Rock Sioux.
He's taking arguments on whether the pipeline should be shut down in the meantime.
The tribe says a shutdown is warranted. The company says a shutdown would impact oil producers and refiners, workers, customers, consumers and government tax revenue.