State and federal officials are now focusing on cleaning up the area where the main Dakota Access Pipeline protest camp was located.
It’s along the Cannonball River, on Army Corps of Engineers land north of the Standing Rock Reservation.
Crews have been working to clean up the debris. They’re dismantling structures, hauling out abandoned cars and filling dumpsters with garbage.
"This isn't just high school kids picking up garbage in a ditch along teh road," Gov. Doug Burgum told reporters at a Mandan news conference.
Burgum said the Corps wants to return the land to its natural state – a process that will take time.
"This is beautiful North Dakota prairie," Burgum said. "Just the damage that has been done to soil by all the driving and the ruts and everything that's in there is substantial.'
And there is concern about the spring melt – and potential flooding. The Corps’ Colonel John Henderson told reporters the goals are safety and health.
"And to insure that none of this garbage and waste, debris and structures and vehicles end up in the Oahe reservoir," Col. Henderson said. "That would be an absolute environmental catastrophe."
Henderson said the Corps has budgeted $800,000 for the clean up – but he says the final cost could be over $1.1 million.