By Terray Sylvester

CANNON BALL, N.D. (Reuters) – A Sioux tribal council on Saturday formally asked hundreds of protesters to clear out of three camps near its North Dakota reservation used to stage months of sometimes violent protests against the proposed Dakota Access Pipeline.

The Standing Rock Sioux Tribe on Friday unanimously passed a resolution calling for the camps to be dismantled, it said on its Facebook page on Saturday. The tribe has been encouraging protesters to go home since the U.S. Army Corps of Engineers agreed to an environmental review of the $3.8 billion project in December.

Despite earlier discussions about alternative sites, the resolution made no provision for relocating the estimated 600 protesters, which include non-native environmental activists and Native Americans from outside the tribe.

“The pipeline fight has moved beyond the camps and our strategy must evolve with the process,” Standing Rock Tribal Chairman David Archambault II said in a statement dated Saturday.

The council said heavy snowfall in the area had raised the danger of flooding, and this week’s clashes with police could imperil the environmental review process.

“Because we worked together, the federal government will prepare an Environmental Impact Statement,” the tribe said. “Moving forward, our ultimate objective is best served by our elected officials, navigating strategically through the administrative and legal processes.”

Native Americans and environmental activists have said that the pipeline would threaten water resources and sacred lands.

The tribe, which launched the effort to stop the pipeline last year, won a major concession when the government denied Energy Transfer Partners an easement for the pipeline to travel under Lake Oahe, a water source upstream from the reservation.

The tribe’s resolution formally called on protesters to leave the area in 30 days, in part because of the potential for environmental damage and safety issues raised by the encampments.

But a former council member said the tribe was also concerned that recent clashes could delay the reopening of a highway linking the reservation to Bismarck, the state capital, an hour’s drive to the north.

“Our main venture that we have on Standing Rock is the Prairie Knights Casino, and Highway 1806 is the main access road,” said Phyllis Young, who currently serves as a consultant to the tribe on the Dakota Access Pipeline.

Tensions increased this week near the construction site, with repeated clashes between protesters and police ahead of Friday’s inauguration of President Donald Trump, an unabashed supporter of the project.

Police used tear gas and fired beanbag rounds to disperse crowds, and have arrested nearly 40 people since Monday, law enforcement officials said.

One of the main groups representing protesters in the camp signaled a willingness to abide by the tribe’s resolution.

“Our network respects the decision of the Cannon Ball district and the tribal council of the Standing Rock Sioux Tribe,” said Tom Goldtooth, the executive director of the Indigenous Environmental Network. “Vacating the camp does not mean abandoning the resistance.”

But Olive Bias, a Cherokee from Colorado who has been at the camps since September, said she expected some people would refuse to leave camp.

“Some will (leave). Others won’t. It’s pretty inevitable,” she said.

(Writing by Frank McGurty, editing by G Crosse)