North Dakota Gov. Doug Burgum announced Tuesday that the federal government is moving in to accelerate the cleanup at the Dakota Access protest camp before the snowmelt turns the area into an “environmental disaster.” Despite weeks of cleanup at the Oceti Sakowin camp led by the Standing Rock Sioux, the job is only about half-finished. Some areas of the camp, which was built on a floodplain, are already under several inches of water. “With near-record high temperatures expected later this week and significant meltwater flooding already occurring, the situation grows increasingly unsafe by the day,” said Mr. Burgum in a...