The people resisting the Dakota Access Pipeline say they aren't going anywhere — despite evacuation orders, freezing temperatures and nearly 2 feet of snow.
The protesters' main campsite is on federal land. The U.S. Army Corps of Engineers has warned them that public access to the site will be cut off Monday.
But the people appear to be preparing for a longer stay. With more snow forecast for the coming weeks, they spent their time building and reinforcing structures to keep out the cold.
A group of U.S. veterans also made the trip to the Oceti Sakowin Camp to act as human shields between protesters and police.
In a letter to President Obama dated Friday, Amnesty International said its teams observed "an over-militarization of law enforcement in response" to the protests and called for an end to the pipeline's construction.
The protesters, who call themselves "water protectors," are worried the pipeline could leak oil into their water supply. They've been calling for an end to the project for months.
That call has gotten louder since the election of Donald Trump, who has voiced support for the pipeline being built.