The meeting was scheduled, in part, to discuss the details of the emergency evacuation order, according to Bigelow.
A source at the camp told ABC News after Thursday's meeting that the federal deadline of Feb. 22 -- the same deadline set by the governor's order -- remains in effect for the camp to be vacated.
Burgum signed an emergency evacuation order on Wednesday night for the Oceti Sakowin protest camp “out of concern for the safety of people who are residing on U.S. Army Corps of Engineers (Corps) land in southern Morton County and to avoid an ecological disaster to the Missouri River,” according to a statement from the Republican governor’s office.
The Standing Rock Sioux Tribe began coordinating a cleanup in late January, but state officials say it isn't happening quickly enough. Burgum’s emergency evacuation order cited increasing temperatures and the threat of flooding as the impetus in accelerating the camp's clean-up.
"Warm temperatures have accelerated snowmelt in the area of the Oceti Sakowin protest camp, and the National Weather Service reports that the Cannonball River should be on the watch for rising water levels and an increased risk of ice jams later this week," the statement from the governor’s office read.
"Due to these conditions, the governor’s emergency order addresses safety concerns to human life as anyone in the floodplain is at risk for possible injury or death. The order also addresses the need to protect the Missouri River from the waste that will flow into the Cannonball River and Lake Oahe if the camp is not cleared and the cleanup expedited," the statement added.
The Cannonball River is a tributary of the Missouri River.
The Army Corps, in a letter issued Feb. 3, ordered those camping on federal property to vacate to prevent injuries and significant environmental damage in the event of flooding in the area.
“The Oceti Sakowin camp needs to be evacuated no later than Feb. 22 in order to allow private contractors to accelerate the removal of waste from the camp,” the statement from the governor’s office read.
Gov. Burgum told ABC affiliate KSTP in Saint Paul, Minnesota, on Thursday that he plans to ask the federal government for more than $33 million for law enforcement and cleanup bills related to the Dakota Access pipeline protest camps that has housed hundreds -- at times thousands -- of protesters.
Bigelow, a member of the Standing Rock Sioux Tribe who has been at the Oceti Sakowin protest camp for the past six months, said law enforcement officials on Wednesday moved up the barricade separating protesters from the pipeline construction area to within a few hundred yards of the camp's north gate, the main entrance. But there was no law enforcement presence south of the barricade ahead of Thursday's meeting, Bigelow said.
Bigelow said there was some tension this morning when front-load tractors and roll-off trucks rolled in to begin removing garbage and waste from the campground, which is situated at the edge of the Standing Rock Sioux Tribe reservation.
“Most folks are concentrating on breaking down their camps to move out of Oceti Sakowin and either back home or to one of the other camps that’s been set up,” he told ABC News on Thursday, ahead of the scheduled meeting.
The Army Corps granted an easement on Feb. 8 to the developer of the Dakota Access pipeline, allowing it to install the final segment of the 1,172-mile pipeline. Part of this 1.25-mile section will run under Lake Oahe, a Missouri River reservoir in North Dakota just upstream of the Standing Rock Sioux Tribe reservation.
“The safety of those located on Corps-managed land is our top priority, in addition to preventing contaminants from entering the waterway,” U.S. Army Corps of Engineers Omaha District Commander Col. John Henderson said in a statement at the time. “We appreciate the proactive efforts of the tribes to help clean the protest site ahead of potential flooding along the river, typical during the runoff season.”
The granting of the easement follows a decision on Feb. 7 by Robert Speer, the acting secretary of the Army, to terminate the notice of intent to perform an environmental impact statement and to notify Congress of the Army’s intent to grant permission for the crossing under Lake Oahe. Speer said the decision was made based on a sufficient amount of available information.
The Standing Rock Sioux Tribe said in a statement at the time that it will “challenge any easement decision” on the grounds that the environmental impact statement was “wrongfully terminated.” The tribe said it will also “demand a fair, accurate and lawful environmental impact statement to identify true risks to its treaty rights, including its water supply and sacred places.”
If the Dakota Access pipeline is completed and begins operating, the Standing Rock Sioux Tribe said it will “seek to shut the pipeline operations down.”
While the Army Corps says this area is federally owned land, the Standing Rock Sioux Tribe cites an 1851 treaty that it says designates the land for Native American tribes. The tribe, which claims its members were never meaningfully consulted before construction began, sued in July to block the $3.8 billion Dakota Access pipeline. That lawsuit is pending, and the Army Corps and the company behind the pipeline argued in court papers that they followed a standard review process.
The Cheyenne River Sioux Tribe, which is part of the Great Sioux Nation, has joined the Standing Rock Sioux Tribe’s lawsuit against the pipeline, filing a motion at the U.S. District Court for the District of Columbia on Feb. 9 seeking a temporary restraining order “to halt construction and drilling” under and on either side of the land surrounding Lake Oahe.
The tribe argued that the pipeline “will desecrate the waters upon which Cheyenne River Sioux tribal members rely for their most important religious practices and therefore substantially burden the free exercise of their religion,” according to a court document obtained by ABC News.
On Monday, the court denied that motion seeking a temporary restraining order.
The Cheyenne River Sioux Tribe filed a separate motion seeking a preliminary injunction directing the Army Corps to withdraw the easement issued to the pipeline company on Feb. 8. The tribe alleges that the easement granted is “entirely unlawful," according to court documents.
“The government has granted the easement, and Dakota Access has begun to drill. This court cannot wait until the harm begins to issue equitable relief. When the free exercise of religion is at stake, a threat certain to that right is enough to constitute irreparable harm,” the Cheyenne River Sioux Tribe stated in a court document.
“And in view of the threat to the tribe’s and its members’ constitutional right, this court may not wait until the oil is slithering under the tribe’s sacred waters. The law entitles the tribe to relief as soon as the government acts to threaten their rights," the Cheyenne River Sioux Tribe added in the court document.
That motion seeking a preliminary injunction is expected to be heard in court later this month.
In addition, the Standing Rock Sioux Tribe filed a motion on Tuesday seeking “expedited summary judgment" on its claims that this easement decision as well as the Army Corps regulatory actions "are arbitrary, capricious and contrary to law."
After receiving the easement to build the pipeline across land on both sides of Lake Oahe, the Texas-based developer, Energy Transfer Partners, announced it would resume construction immediately, and indeed work has resumed.
The Dakota Access pipeline, which would connect oil production areas in North Dakota to an existing crude oil terminal near Patoka, Illinois, is expected to be in service in the second quarter of 2017, according to the company.
“The drilling under Lake Oahe will take approximately 60 days," a company spokesperson told ABC News in a statement on Feb. 8 after the Army Corps granted the easement. "It will take an additional 23 days to fill the line to Patoka, Illinois, enabling Dakota Access to be in service in approximately 83 days."
The Standing Rock Sioux Tribe has been at the forefront of massive and prolonged protests over the four-state crude oil pipeline. The demonstrations have drawn thousands of Native Americans, environmental activists and their allies to the Standing Rock Sioux Tribe reservation. The protesters, who call themselves "water protectors," argue that the pipeline will threaten the reservation’s water supply and traverse culturally sacred sites.
Kelcy Warren, the CEO of Energy Transfer Partners, has said that “concerns about the pipeline’s impact on local water supply are unfounded” and “multiple archaeological studies conducted with state historic preservation offices found no sacred items along the route.”
In the final days of President Barack Obama’s administration, Jo-Ellen Darcy, the assistant secretary of the Army for civil works, announced on Dec. 4 that an easement would not be granted for the pipeline to cross under the large reservoir on the Missouri River.
She said at the time of the decision that the Army Corps would engage in additional review and analysis, including a “robust consideration and discussion of alternative locations for the pipeline crossing the Missouri River.” Darcy also encouraged the Corps to share company documents containing risk analyses and spill models that had not been made available to the tribes during the initial environmental review.
All these steps, Darcy determined, would best be accomplished by the Army Corps’ preparing a full environmental impact statement allowing for public input -- a process that could have take years. She is no longer in the position after the change in administrations.
The move to deny the easement was hailed by the Standing Rock Sioux Tribe and other pipeline opponents as a major victory. But on his second weekday in office, President Trump signed a memorandum aimed at advancing the Dakota Access pipeline, as well as one directed at the Keystone XL pipeline.
At a news conference at the White House on Thursday, Trump told reporters his administration has “taken steps to begin construction” of the two pipelines.
ABC News' David Caplan, Joshua Hoyos, Luis Martinez, Darren Reynolds, Evan Simon and Catherine Thorbecke contributed to this report.