The US Army Corps of Engineers and North Dakota Governor Doug Burgum gave protesters until 2 p.m. Central Time on Wednesday to vacate the camp.
On February 8, the Corps of Engineers granted easement needed to immediately resume work on the final phase of the pipeline, which was in limbo pending an environmental impact statement since December.
President Donald Trump signed on January 24 an executive order to advance construction of the Dakota Access pipeline without the environmental review.
The nearly 1,200-mile pipeline is intended to transport domestically produced light crude oil from North Dakota through the states of South Dakota and Iowa into Illinois.
Native American tribes opposed the pipeline’s construction, claiming it threatens sacred territory and vital drinking water sources.