Jo-Ellen Darcy, who has been Assistant Secretary of the Army for Civil Works, previously helped draft the Safe Drinking Water Act

A bureaucrat overruled a recommendation by the Army Corps of Engineers which would have allowed construction of the controversial Dakota Access pipeline to go ahead, it has emerged.

The company behind the project had sought an easement to begin construction.

But following months of sometimes violent protests the Army Corps of Engineers said on Sunday it would find another path for the pipeline.

Now it has been reported that the corps recommended approval but because the pipeline was 30in in diameter it had to be referred up to Assistant Secretary of the Army for Civil Works, Jo-Ellen Darcy, a civilian.

Her spokesman, Moira Kelley, told NBC News: 'Ms Darcy had the authority to make the decision on behalf of the Department of the Army, and she did so.'

When asked why Ms Darcy decided to go against the Corps of Engineers' recommendation, Ms Kelley said: 'The Army decided that the totality of circumstances call for additional analysis, a more robust consideration of alternatives, and additional public information.'

The pipeline is proposed to bring crude oil down from North Dakota but it runs directly across land belonging to the Standing Rock Lakota tribes

A Stars and Stripes flag is flown upside down as a sign of protest as blizzard conditions grip the protest camp on the Standing Rock reservation in North Dakota

Wigwams stand in the snow at the protest camp at Standing Rock. Native American leaders say the pipeline is in breach of a treaty signed by the United States in the 19th century

Those who oppose the pipeline say its construction threatens land on the Standing Rock reservation, which is believed to be sacred to the Lakota nation, sometimes referred to as the Sioux.

But they also point out that if the pipeline were to leak it could pollute the crucial Ogallala aquifer, which supplies drinking water to thousands of people across the Great Plains.

Before she was appointed to her current job in 2009, Ms Darcy spent years working in environmental protection working on a variety of issues, including the Safe Drinking Water Act.

A spokesman for Donald Trump said on Monday the president-elect is in favor of building the Dakota Access pipeline, and will revisit the decision to halt construction until it can be routed around land belonging to the Standing Rock Sioux tribe.

Trump spokesman Jason Miller said the crude oil conduit was 'something that we support construction of, and we'll review the full situation once we're in the White House and make an appropriate determination at that time.'

Donald Trump supports the Dakota Access pipeline and will 'review the full situation' as president, a spokesman said after the Army Corps of Engineers caved to protests and said it will seek an alternate route for the project

While the announcement signaled a victory for the Standing Rock Sioux and their supporters, some remained cautious, saying it was unclear what would happen when Trump takes office

Protesters at the Standing Rock Indian reservation rejoiced as the Obama administration backed down from its plan to enforce an easement that would allow a pipeline to be built on their land

Ms Darcy said in a statement on Sunday: 'Although we have had continuing discussion and exchanges of new information with the Standing Rock Sioux and Dakota Access, it's clear that there's more work to do.'

'The best way to complete that work responsibly and expeditiously is to explore alternate routes for the pipeline crossing.'

She also added the new routes will be explored using an environmental impact statement, 'with full public input and analysis'.

Representative Kevin Cramer, a North Dakota Republican, said the move was a 'chilling signal to others who want to build infrastructure in this country.'

'I can't wait for the adults to be in charge on January 20,' said Cramer, a supporter of President-elect Donald Trump, who will be inaugurated as president on that day.

Opponents of the controversial pipeline celebrated the decision with a late-night fireworks display

The company behind the pipeline want to bring the oil all the way down to a refinery in Illinois

The company building the $3.8billion oil pipeline slammed the Obama administration.

Dallas-based Energy Transfer Partners released a statement on Sunday night calling the decision 'just the latest in a series of overt and transparent political actions by an administration which has abandoned the rule of law in favor of currying favor with a narrow and extreme political constituency.'

The Standing Rock Lakota tribe and its supporters have long argued the project would threaten Lake Oahe as a water source and cultural sites.

The Army's Assistant Secretary for Civil Works said a new route will be explored in consideration of an environmental impact statement along 'with full public input and analysis'

Standing Rock tribal chairman Dave Archambault II said 'The Standing Rock Sioux Tribe will forever be grateful to the Obama administration for this historic decision' – but the Trump administration could reverse it with the stroke of a pen

Thousands of demonstrators at the Oceti Sakowin campsite erupted into cheers and cries of 'Mni Wiconi' – 'Water is life' – went up from the crowd as Sunday's news spread.

Moments after the decision was announced, Cheyenne River Sioux Tribal Council Chairman Harold Frazier told DailyMail.com that he was 'shocked' by the news.

The pipeline running through North Dakota, South Dakota, Iowa and Illinois is mostly complete, except for a segment planned to run under Lake Oahe, which protesters resisted for several months.

Faith Spotted Eagle, an elder of the Ihanktonwan tribe, said: 'The easement has been denied. We have all come to this gathering being hosted by Mother Earth. I love you all.'

Shailene Woodley, star of the 'Divergent' movies and 'The Fault in Our Stars', who had previously been arrested while protesting told a huge crowd: 'We feel so honored to have been a small part of this movement.'

Protesters opposed the $3.8 billion pipeline, saying the project, slated to carry 570,000 barrels of crude oil a day across four states, could harm drinking water and cultural sites