The U.S. Army Corps of Engineers gave evacuation orders to protesters at a camp near Lake Oahe in Cannon Ball, N.D., last Friday.
Citing safety and environmental concerns, the Corps said that it would close the Oceti Sakowin Camp — located at the confluence of the Missouri and Cannonball Rivers — on Feb. 22 because of a "high potential for flooding" in the low-lying area, especially due to a record snowfall in the winter season. They also said that the "unauthorized placement of structures, vehicles, personal property, and fires" contributes to soil erosion and pollution which can result in contaminated waste seeping into both rivers.
The Bureau of Indian Affairs will also be sending agents to help clear protesters from the Standing Rock Sioux reservation.
The Sioux tribe and supporters have been lobbying against federal approval of the 1,170 mile pipeline being constructed by Energy Transfer Partners, saying the pipeline's construction will disturb sacred burial grounds and potentially pollute vital water sources by laying line under the rivers.
The Corps says the camp has contributed to erosion in the area which, combined with heavy snowfall this season, could make spring flooding worse.
The Trump administration earlier directed the Corps to speed up their review and approval process for the last leg of the pipeline's construction.