The US Army Corps of Engineers has granted the final easement for the controversial Dakota Access Pipeline in North Dakota. The easement allows the construction of the pipeline under Lake Oahe on the Missouri River to move forward despite continued protests by the Standing Rock Sioux tribe and environmental activists.

The Standing Rock Sioux have protested against the completion of the pipeline, arguing that it threatens its drinking water supplies there. Protesters won a small victory during the last weeks of President Barack Obama's administration when the construction was briefly stalled. However, President Donald Trump in January ordered construction to move forward.

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According to The Hill, Trump administration officials informed Congress and a federal judge on Tuesday (7 February) that the easement would be issued. The Corps announced on Wednesday (8 February) that it was working with local and tribal officials to clear the area where construction would begin. The land is near the protest camp set up by the Standing Rock Sioux and anti-pipeline demonstrators last August.

"The safety of those located on Corps-managed land remains our top priority, in addition to preventing contaminants from entering the waterway," Colonel John Henderson, the Omaha District Commander of the Army Corps, said in a statement. "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."

Energy Transfer Partners, the parent firm of the company building the pipeline, confirmed it had received the necessary permits to complete the pipeline. In a statement, Energy Transfer Partners spokeswoman Vicki Granado said work would begin "immediately," according to CNN.

News of the granting of the easement was not received too kindly by Standing Rock Sioux Chairman David Archambault II, who had arrived in Washington on Tuesday to make a last-minute pitch during a scheduled meeting at the White House the following day. According to The Washington Post, Archambault learned of the Army Corps' decision after landing at Reagan National Airport.

"I just feel that I was slighted. I was disrespected. I think that I was set up," he said.

On Wednesday, Trump said he did not receive any indication that anyone opposed the pipeline's completion. "I did the Dakota pipeline, and nobody called up to complain," the president said. "I haven't had one call from anybody."

However, Archambault told the Post. "My intention for meeting anyone in the White House who is willing to listen is to just share why there is a movement, why there is resistance," he said. "And help them understand all the wrongs that have been committed to my nation by this nation."

The tribal leader said he is not asking protesters to flood North Dakota again but instead is encouraging everyone to go to their state capitals and congressional districts. "We're going to have a march here in DC on 10 March. We have to let everyone know that indigenous people are united ... We're not going anywhere."

The Standing Rock Sioux Tribe has also promised a legal fight, CNN reported.