The U.S. Army Corps of Engineers violated a key federal environmental law when it approved an easement for the Dakota Access Pipeline to cross under the Missouri River and now must complete a full environmental impact statement, a federal appeals court in Washington, DC ruled Jan. 26.

But the court overruled a lower court that the $3.8 billion, 1,172-mile pipeline had to stop operating and empty its oil until that review was done. The decision partially upholds the March 2020 ruling by D.C. District Court Judge James Boasberg, but the shutdown he ordered was not enacted pending the appeal. 

Boasberg on Feb. 8 granted a Corps request to postpone to April 9 a Feb. 10 hearing to discuss how the agency expects to proceed now that the permit to cross the river is vacated, to enable Biden Administration officials to understand case details

He also expects to discuss how the ruling affects a separate request by tribes of the Sioux Nation to shut down the pipeline that was brought under a different legal standard

In its review, the Corps could still order pipeline shutdown..

Four Sioux tribes on Jan. 19 asked President Joe Biden to direct the Corps to shut down the pipeline. “Pressure on the Biden Administration is growing,” says Jan Hasselman, an attorney with Earthjustice.

A coalition of prominent congressional, entertainment industry and other opponents also sent letters in early February to the president against pipeline operation, but with Republican lawmakers such as North Dakota's two Senators urging no presidential intervention.

The court declared the Corps' simple environmental assessment for the project is a violation of the National Environmental Protection Act, which requires that construction permits be issued only after “taking a hard look at the project’s environmental consequences.”

The pipeline moves about 570,000 barrels of crude oil from North Dakota to Illinois daily, including a crossing of Lake Oahe on the Missouri River between North and South Dakota, a waterway used by the Standing Rock Sioux for drinking water and more. The pipeline crosses the river about one half mile from the Standing Rock reservation.

The EIS must study the risk that an oil spill poses to the Standing Rock Sioux, the court said. The Corps will decide whether to reissue the permit or require an alternative route that mitigates risk to the tribe.

The district court found that a serious unresolved controversy existed concerning the effectiveness of the pipeline’s leak detection system. It was not designed to detect leaks of 1% or less of the pipe’s flow rate, which would amount to 6,000 barrels a day.

When asked why the assessment did not evaluate the potential consequences of an undetected slow pinhole leak, the Corps said “there was no particular reason” why it did not.

“The tribes’ criticisms therefore present an unresolved controversy requiring the Corps to prepare an EIS,” the appeals court said.

Earthjustice says the Biden administration has discretion to issue an interim shutdown to bring the pipeline into compliance with federal law while the EIS proceeds.

In 2015, the Corps issued a draft environmental assessment finding construction would have no significant environmental impact. Both the Interior Department and the Environmental Protection Agency raised concern that the assessment lacked significant analysis of the impact on water resources.

The Corps decided in January 2017 to prepare an EIS, according to the appellate ruling, but when the new administration came into office four days later, President Donald Trump directed the Corps to expedite approvals and reconsider the EIS.

The Corps in February 2017 granted the easement for the pipeline to travel under the lake.

“With the planet in the midst of a climate emergency, we are out of time for making allowances for the fossil fuel industry,” says Chase Iron Eyes, lead counsel for the Lakota Sioux’s law project.

Sen. John Hoeven, R-ND, said the pipeline is critical to the American economy and national security. “This project was built and operated in good faith under an Army Corps’ permitting process,” he said in a statement.

Neither Energy Transfer Partners nor the North Dakota Petroleum Council responded to a request for comment.