Construction activities must stop on a controversial highway through critical Mojave desert tortoise habitat in southwest Utah, a federal judge ordered this week.

U.S. District Court Judge Randolph D. Moss granted a motion for a preliminary injunction on Sunday evening, halting progress on the controversial Northern Corridor highway through the Red Cliffs National Conservation Area.

The judge’s ruling prevents federal agencies from issuing any notices to proceed associated with the highway and suspends all activities that the agencies had previously given UDOT permission to begin, such as staking.

This decision comes after conservation groups, including Conserve Southwest Utah and the Southern Utah Wilderness Alliance, sued the federal government over its approval of the highway in January. The Utah Department of Transportation began staking the right-of-way soon after they received the go ahead and had plans to install fencing this spring.

“We’re pleased the court saw through the false sense of urgency by UDOT and Utah politicians to start work on the Northern Corridor Highway through Red Cliffs National Conservation Area,” Stacey Wittek, executive director of Conserve Southwest Utah, said in a news release on Monday.

The Mojave desert tortoise is a federally-listed threatened species, and the Northern Corridor highway would pave over a section of the Red Cliffs National Conservation Area with a high density of tortoises.

Washington County for years has pushed for the highway to help solve its current and projected traffic woes as southwest Utah’s population grows.

“This community has waited long enough, and we will not allow this obstruction to continue without a fight,” the Washington County Commission said in a statement on Monday.

The injunction remains in effect until the judge issues another order or a final ruling in the case.

“Some may attempt to characterize this injunction as yet another court rejection of the Northern Corridor,” the county commission said in its statement. “That claim is false.”

This is not the first time conservation groups and the federal government have been to court over the Northern Corridor. In 2021, federal agencies approved the highway during the final days of President Donald Trump’s first term. Conservation groups sued, and the two sides eventually reached a settlement agreement. The Bureau of Land Management reversed its approval of the highway at the end of the Biden administration in 2024.

In his ruling, Judge Moss said the plaintiffs have “demonstrated a likelihood of success” in at least two of its claims, including that the Bureau of Land Management did not adequately explain why it reversed its previous decision that the Northern Corridor was unlawful.

Moss also said that the court will “set an expedited schedule to resolve the case.”