By Max Blau, Kait Richmond and Marisa Russell CNN

(CNN) -- [Breaking news update, posted at 2:07 p.m. ET]

Law enforcement will begin Tuesday to block all people and supplies from coming to the Dakota Access Pipeline protest campsite, Morton County Sheriff's Department spokeswoman Maxine Herr told CNN.

North Dakota's Governor has ordered protesters to vacate and sheriff's deputies will enforce the order, Herr said.

[Previous story, posted 7:58 a.m. ET]

The protesters fighting to block the Dakota Access Pipeline have vowed to stand their ground in opposition despite growing calls for them to move out of the way.

Since late summer, protesters have stood beside members of the Standing Rock Sioux Tribe in North Dakota who believe the $3.7 billion pipeline project, which would move 470,000 barrels of crude oil a day across four states, would affect its supply of drinking water and place downstream communities at risk of contamination from potential oil spills.

In an interview with CNN's Chris Cuomo, Standing Rock Sioux Tribal Chairman Dave Archambault said they would continue the protest even thought they've been ordered to vacate an area where they have set up camp by December 5.

"We are in for the long haul," said Chase Iron Eyes, a member of the Standing Rock Sioux Tribe.

Pressure grows, protesters dig in

This past Friday, the US Army Corps of Engineers warned that activists who refuse to leave could face arrest. Since the statement's release, however, officials have backtracked, saying they have no plans to forcibly remove those who stay.

Now, a week before the deadline, North Dakota Gov. Jack Dalrymple has ordered protesters to clear out immediately for a different reason other than trespassing: harsh winter conditions.

In a statement, he said the protesters' temporary dwellings have yet to be inspected and approved -- failure to do so posed serious public safety and concerns. He added that first responders would no longer be responsible for providing emergency services to those who remained.

Native Americans reminded of past treatment

For Iron Eyes, the initial threats of arrest have brought back memories of the government's past treatment of Native Americans.

"You have a government agency trying to declare us trespassers on our own treaty land and threatening to penalize us, criminally charge us and possibly forcibly round us up if we don't return to the reservation," he said.

The pipeline was originally slated to lie north of Bismarck, North Dakota, in an area that did not cross Native American reservations. The current proposed route, however, would take it through four states, stretching 1,172 miles to connect areas with oil in North Dakota to southern Illinois.

It would cut through the Sioux Tribe's reservation, and the tribe says it could potentially destroy sacred lands and prevent access to clean drinking water.

"We're trying to stay strong through all of this," he said.

Six days left

Over the months of protest, the tribe has been joined by multiple groups and activists. They maintain that they have been peaceful, but at times violence has erupted.

The Morton County Sheriff's Office said protesters set fires while officers tried to disperse the crowds with tear gas, rubber bullets and water sprayed from hoses attached to fire engines.

Archambault said the accusations against the protesters are false, and that it's police who are being violent.

"They are the ones who are bringing the aggression," he said. "They're the ones who are using weapons."

He said the letter from the Army Corps will only make things worse.

"By sending out a letter saying you have until December 5," he said. " ... It just escalates and causes more concern for safety for everybody."

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