Celebrations erupted through the North Dakota Access pipeline protest camp as it was announced the federal government won't grant an easement for the project in southern North Dakota.
Hundreds of demonstrators near the Dakota Access pipeline protest camp broke into cheers and chanted "water is life" in the Lakota Sioux language as the news spread.
Some in the crowd banged drums.
Miles Allard of the Standing Rock Sioux tribe said he was pleased by the decision but remained cautious, saying opponents of the pipeline "don't know what Trump is going to do".
Allard said he's been telling his people "to stand up and not to leave until this is over".
Carla Youngbear of the Meskwaki Potawatomi tribe travelled from central Kansas to be at the protest site. She said she has grandchildren and is going to have great-grandchildren who will need water and that's why she was there.
On social media the mood was similarly jubilant as protesters both at the camp and around the US celebrated the news.
"This is a historic moment for the Standing Rock Sioux and the water protectors who have gathered here from across the country," she said.
"This announcement in effect requires the Dakota Access Pipeline to be rerouted—an essential step in protecting water for millions of people in this region as well as respecting this sacred land.
"In my meeting yesterday with Tribal Chairman Dave Archambault, he emphasised the importance of caring for our planet not as a resource, but as our relative."
But while the celebrations continued, there was still caution in the wind, as the easement is only one hurdle for the controversial pipeline.
North Dakota Governor Jack Dalrymple said in a statement that the Corps' decision "is a serious mistake", "prolongs the serious problems" that law enforcement faces and "prolongs the dangerous situation" of people camping in cold, snowy conditions.
His words were echoed by North Dakota Republican Congressman Kevin Cramer who said the Army Corps' decision not to grant an easement for the Dakota Access oil pipeline is "a very chilling signal" for the future of infrastructure in the US.
Cramer said in a statement that infrastructure will be hard to build "when criminal behavior is rewarded this way", apparently referring to the large protest encampment on federal land and the clashes between demonstrators and law enforcement.
Republican House Speaker Paul Ryan said the decision was "big government decision-making at its worst".
The Wisconsin Republican tweeted Sunday night he looks "forward to putting this anti-energy presidency behind us".
The protests were marked with violence and arrests with a heavy police presence.
One protester, Sophia Wilansky, 21, was injured during a protest on November 20, allegedly by a concussion grenade fired by police, and was in danger of losing her arm.
There were reports at least 300 people were injured in the same protest and 26 had to be taken to hospital for blunt force trauma and open wounds.
Ms Wilansky's father Wayne Wilansky told The Guardian at the time his daughter was in surgery for eight hours and may still have to have her arm amputated.
"The best-case scenario is no pain and 10-20 per cent functionality," he said.
"She’s devastated. She looks at her arm and she cries."
- with AAP, DPA
