By Steve Almasy CNN

(CNN) -- The controversial Dakota Access Pipeline project -- bitterly opposed and vilified by Native Americans and environmentalists -- might be a big step closer to fruition.

But a tribe fighting the pipeline is moving full-steam ahead in court to stop the project.

The US Army Corps of Engineers granted an easement in North Dakota for the pipeline, a move enthusiastically greeted by the project builders.

Work would start "immediately," said Vicki Granado, spokeswoman for Energy Transfer Partners, the parent firm of the company building the pipeline.

"Dakota Access now has received all federal authorizations necessary to proceed expeditiously to complete construction of the pipeline," Energy Transfer Partners said in a statement.

But the Standing Rock Sioux Tribe and its allies say the easement shouldn't have been granted without the issuance of an environmental impact statement, or EIS for short.

"The Trump administration may have announced termination of the EIS, but that will not go unchallenged. This administration has expressed utter and complete disregard for not only our treaty and water rights, but the environment as a whole," the tribe said in a statement.

Trump's executive action

The fate of the project changed after the election of President Donald Trump.

Trump signed executive actions a few weeks ago to advance approval of the pipeline. His flick of a pen cast aside efforts by President Barack Obama's administration to block construction.

Trump's order directed "the acting secretary of the Army to expeditiously review requests for approvals to construct and operate the Dakota Access Pipeline in compliance with the law."

Acting Secretary of the Army Robert Speer's moves to grant the easement and stop the preparation of an environmental impact statement were anticipated.

"The decision was made based on a sufficient amount of information already available which supported approval to grant the easement request," the Army said Tuesday.

Speer called granting the easement a "final step" in meeting the tasks of the President's executive action.

The Standing Rock Sioux tribe, which has long opposed the part of the project near its home, plans argue in court that the environmental impact statement process was wrongfully terminated.

The tribe is demanding a proper environmental impact statement to identify risks to its treaty rights, including its water supply and sacred places.

It wants disclosure of oil spill and risk assessment records, and it will seek to shut down down pipeline operations if the construction is successful.

The tribe said the Obama administration had determined other locations for the pipeline, and those should be looked into by the Army.

"The Obama administration correctly found that the Tribe's treaty rights needed to be acknowledged and protected, and that the easement should not be granted without further review and consideration of alternative crossing locations," said Jan Hasselman, lead attorney for the tribe.

"Trump's reversal of that decision continues a historic pattern of broken promises to Indian Tribes and unlawful violation of Treaty rights," he said. "They will be held accountable in court."

The decision gives the pipeline's developer -- Dakota Access, a subsidiary of Energy Transfer Partners -- right-of-way through government land at Lake Oahe Dam and Reservoir in North Dakota.

The tribe has been concerned that digging the pipeline under Lake Oahe -- a section of the Missouri River in North Dakota -- would affect the area's drinking water, as well as the supply for 17 million people living downstream.

The proposed underground route at Lake Oahe is half a mile upstream from the tribe's reservation.

Greenpeace said the President was looking out for the rich.

"We are less than two weeks into this administration, and already Trump has put on full display a blatant disregard for Indigenous sovereignty, public health, and public outcry," the environmental organization said. "This decision to smash through the (environmental impact statement) process is nothing but a reward to Trump's corporate, oil industry cronies."

Runs more than 1,100 miles

Dakota Access and pipeline supporters say the $3.7 billion pipeline project would be an economic boon.

The developer estimates the pipeline would bring $156 million in sales and income taxes to state and local governments and would add 8,000 to 12,000 construction jobs.

The pipeline would stretch 1,172 miles through four states -- from North Dakota into South Dakota, winding through Iowa and ending in southern Illinois -- moving 470,000 barrels of crude oil a day across the Midwest. It is completed, except for the contested portion under Lake Oahe.

Like Dakota Access, the Keystone XL Pipeline had been the subject of environmental concern from activists, residents and indigenous tribes who worried that the pipeline would pollute as many as 2,500 aquifers.

But pipeline supporters touted the jobs it would create and other economic benefits.

The $8 billion Keystone pipeline was proposed to stretch nearly 1,200 miles across six states, shuttling carbon-heavy petroleum from Canada to the Gulf Coast.

In November 2015, Obama nixed the proposed pipeline, virtually ending the fight over the project that had gone on for much of his presidency.

But Trump's executive actions on both pipelines signal how his administration will take a different approach to energy and environmental issues.

CNN's Keith Allen, Joe Sterling, Holly Yan, Madison Park, Jessica Ravitz and Sara Sidner contributed to this report.

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