The Dakota Access Pipeline (DAPL) may continue operating during a federal review of the project’s environmental impact, a judge overseeing the case ruled on Wednesday.

U.S. District Judge James Boasberg said he would not vacate a previous permit while an environmental review is conducted of the pipeline. The U.S. Army Corps of Engineers said in a court filing last Friday that its environmental review may take until April to complete.

In June, Boasberg ruled that the environmental review for DAPL was in part inadequate and needed to be reconsidered. He previously ruled twice against challenges to DAPL by the Standing Rock Sioux Nation.

However, in the 28-page ruling Wednesday, Boasberg said the federal review’s deficiencies were not “fundamental or incurable flaws.” The Army Corps has a “significant possibility of justifying its prior determinations,” which means the pipeline may continue operating.

The federal review “cannot be reduced to a bureaucratic formality,” Boasberg wrote. He suggested he may reconsider whether regulators have “fulfilled their statutory obligations” should new legal challenges arise when the review is complete.

“The dispute over the Dakota Access Pipeline has now taken nearly as many twists and turns as the 1,200-mile pipeline itself,” he wrote.

The Army Corps said the review may take longer than anticipated because it needs to obtain oil spill monitoring data from DAPL sponsor Energy Transfer Partners LP as well as at least one of the Native American tribes involved in the court proceedings.

The Standing Rock Sioux, Cheyenne River Sioux and environmental supporters have attempted to halt DAPL operations since before it began flowing oil, arguing that the pipeline threatens water quality as it crosses the Missouri River at Lake Oahe upstream from the Standing Rock Indian Reservation in North Dakota.

Separately, a FERC court filing in another case could hold implications for the DAPL system. FERC last month issued a draft supplemental environmental impact statement for the Sabal Trail Pipeline and two related pipeline expansions, addressing an August appeals court opinion that vacated and remanded its certificate for the projects.

The August ruling issued by the DC Circuit found that the Federal Energy Regulatory Commission had failed to adequately analyze downstream greenhouse gas emissions that would result from the Southeast Market Pipelines project, which includes Sabal Trail, the Florida Southeast Connection pipeline and the Transcontinental Gas Pipe Line Co. LLC Hillabee Expansion.

The FERC appeal matters to DAPL’s case, according to ClearView analysts. The Native American tribes opposing DAPL cited the Sabal Trail ruling in requesting the approvals be vacated and operations ceased.

Boasberg “has not issued his order on remedy, and we think he might wait until the DC Circuit rules, given the DC Circuit decisions are binding precedent for the DC District Court,” said ClearView analysts. He could wait because decisions to resolve issues related to the National Environmental Policy Act (NEPA) “are binding precedent” for the circuit court.

If the DC Circuit rejects FERC’s request for remand without vacating the orders, “we would expect Judge Boasberg could be more inclined to suspend Dakota Access operations while the Corps resolves the NEPA issues associated with the Lake Oahe approvals,” analysts said.

“The Corps did not request a 90-day stay, so a DC Circuit ruling granting that option would not appear to favor either outcome. However, if the DC Circuit grants FERC’s request to remand but not vacate the Southeast Market Projects orders, we would expect Judge Boasberg to remand the Corps’ flawed NEPA analysis without vacatur, too.”