North Dakota's new governor warned on Tuesday that protesters remaining at the construction site of the Dakota Access Pipeline should vacate their main camp before spring because of the risk of flooding.
The site of the $3.8 billion project, which crosses four states, was the scene of demonstrations by Native Americans, environmentalists, military veterans and celebrities who said the North Dakota portion would harm water resources and sacred lands.
In early December, the U.S. Army Corps of Engineers denied an easement needed to allow the pipeline to run under Lake Oahe, a reservoir formed by a dam on the Missouri River.
The Standing Rock Sioux, whose land is adjacent to the pipeline, asked the thousands of protesters to disperse after the decision. Most did so, but some have remained despite the harsh winter conditions.
"The main protest camp is located directly in the floodplain of the Cannonball-Missouri river confluence. Given the snowfall we're having this winter and historic data on the Cannonball River, that camp will likely flood in early March," Governor Doug Burgum said in his State of the State address in Bismarck.
"Anything less than a complete restoration of the area prior to the early March flood will endanger the lives of the protesters and of our first responders," added Burgum, a Republican who took office last month.
Burgum, who supports completion of the pipeline, reiterated the position of law enforcement officials who have said many of the demonstrators were from outside North Dakota and had undercut genuine concerns over water rights.
"Those original concerns have been hijacked by those with alternative agendas," he said.
Burgum, a tech industry veteran who was elected in November, pledged to begin meeting with tribal leaders this week. The pipeline, he said, had highlighted the need to address historic injustices against Native Americans.
"The history of American settlement and westward expansion contains many tragic episodes of broken promises, displaced native peoples and forced assimilation," he said. "It is in this context that the Standing Rock situation must be understood."
Energy Transfer Partners LP, which is building the pipeline, has gone to federal court for a permit to complete the job. It has said the 1,172-mile (1,885-km) pipeline, which is nearly finished, would be a more efficient and safer means to transport oil from the Bakken shale of North Dakota.