BISMARCK, N.D. — A federal judge will hear arguments today about whether to stop the final bit of construction on the disputed Dakota Access pipeline, perhaps just days before it could start moving oil.

U.S. District Judge James Boasberg in Washington, D.C., will consider a request by the Standing Rock and Cheyenne River Sioux tribes to order the Army Corps of Engineers to withdraw permission for developer Energy Transfer Partners to lay pipe under Lake Oahe in North Dakota. The stretch under the Missouri River reservoir is the last piece of construction for the $3.8 billion pipeline that’s to move oil through the Dakotas and Iowa to a shipping point in Illinois.

The tribes argue that the mere existence of an oil pipeline under the reservoir that provides water to the neighboring reservations violates their right to practice their religion, which relies on clean water.