A highway through tortoise habitat? What the Northern Corridor’s revival means for southern Utah

St. George • Orange-red cliffs hug the northern edge of St. George. Past the last homes and buildings, sand, saltbush, yucca and sandstone extend for miles.

That expanse, known as the Red Cliffs Desert Reserve, was set aside by Washington County in 1996 after the federal government listed the Mojave desert tortoise as threatened.

It has also been a battleground over a highway that would pave over the red rock and sagebrush and fragment critical tortoise habitat. But backers say it’s needed to ease Washington County’s traffic woes.

The Trump administration last month reapproved the controversial Northern Corridor highway, a four-lane road through the Red Cliffs National Conservation Area. Environmental groups, including Conserve Southwest Utah and the Center for Biological Diversity, filed a lawsuit challenging the project two weeks later.

These latest moves reignite a decades-long fight over transportation planning, environmental laws and how much development the reserve — and the desert tortoise it was created to protect — can withstand as southwest Utah’s population booms.

The Red Cliffs Desert Reserve is large — over 60,000 acres — and it takes several shapes. Nearly three-quarters of it is protected as a national conservation area. One stretch, set aside as Snow Canyon State Park, attracts around a million hikers, cyclists and climbers each year. Quiet, roadless areas have wilderness designation, while other spots buzz with power lines and cars speeding by on roads that snake along and through the landscape.

If constructed, the four-lane highway will span about 4.4 miles from the Green Springs neighborhood in the east to the Red Hills Parkway in the west.

Washington County, which has been pushing for this highway for years, celebrated the Trump administration’s decision.

“[I’m] very happy that this administration saw the reason and the holistic benefit for all user groups, wildlife, habitat, conservation, that they saw the wisdom in the deal that was struck before and reversed course from the Biden administration decision, which I believe was wholly political,” County Commissioner Adam Snow told The Tribune.

The Bureau of Land Management first approved the highway through the conservation area near the end of President Donald Trump’s first term. Environmental groups sued and later reached a settlement agreement with the federal government, which overturned the approval in the final months of the Biden administration.

“Preservation of Red Cliffs National Conservation Area is inextricably linked to the quality of life and economic prosperity in Washington County,” Stacey Wittek, director of Conserve Southwest Utah, said in a statement. “Our community has repeatedly made clear that better traffic solutions exist and that they oppose a highway through what should be protected lands.”

As another legal battle takes off, the future of the highway, tortoise habitat and a popular recreation area remains uncertain.

What happens now?

Wood lath stakes with neon green and pink survey tape now stick out from the orange sand where the Northern Corridor will run.

UDOT has been staking out the right-of-way, Kirk Thornock, director of UDOT’s southern Utah region, told The Tribune. A biologist joined the survey team to denote any tortoise burrows as well, he added.

UDOT’s immediate work motivated environmental groups to file a lawsuit quickly. “Given that UDOT is wasting no time moving forward with ground-distributing activities, we had to act to stop this illegal project,” Wittek said.

UDOT will move through legal proceedings and determine how that affects its plans, John Gleason, spokesperson for the department, told The Tribune.

At the end of January, UDOT had not been approved for any additional work on the highway, and Thornock said there was not currently a timeline for design and construction.

Before the lawsuit was filed, the county, UDOT and Division of Wildlife Resources began working on a land exchange that would transfer 46 acres of the division’s land in the Northern Corridor’s path to UDOT and 450 acres of the county’s land in the greater Moe’s Valley area to the division.

The entities must close on the deal by the end of March, according to the county’s resolution.

Environmental groups filed for a preliminary injunction on Feb. 10 to temporarily stop further progress on the Northern Corridor while waiting for a ruling on the case, according to court documents.

What this means for Moe’s Valley

As part of the agreement over the highway, the county has added roughly 6,800 acres of land in greater Moe’s Valley, a popular hiking, biking and climbing area that is also home to desert tortoises, into the larger reserve to offset the damage and environmental harm the highway will cause.

Nearly all of that land, referred to as “Zone 6,” is considered occupied Mojave desert tortoise habitat, according to the BLM’s September 2025 biological assessment.

Over a third of that area was already a BLM-designated area of critical environmental concern for the dwarf bear-poppy, an endangered plant that only grows in southwest Utah. But not all of Zone 6 has such levels of protection.

The Utah Trust Lands Administration owns roughly 3,000 acres in the eastern half of Zone 6. If the Northern Corridor doesn’t go through, the agency has said it will develop those lands with proposals ranging from a luxury resort to affordable housing.

The area includes popular mountain biking, hiking and climbing destinations, such as the Zen Trail and Moe’s Valley boulders.

The county has begun “working diligently” to return management to Zone 6, Cameron Rognan, administrator of the county’s Habitat Conservation Plan, said during a meeting of the Habitat Conservation Advisory Committee on Jan. 28.

This has included instructing law enforcement to patrol the area more frequently, updating and reinstalling signage, fixing fencing and recruiting a new outreach coordinator and a new field technician.

“It’s all hands on deck for Zone 6,” Rognan said.

If the lawsuit reverses the decision on the Northern Corridor, protections for Zone 6 will go away again.

Outdoor advocates expected this flip-flopping to continue. Supe Lillywhite, manager of the outdoor shop The Desert Rat, said he wasn’t surprised by the Trump administration’s decision nor the environmental groups’ lawsuit.

The longer legal fighting continues, he said, the more likely the Trust Lands Administration will develop its land in Zone 6.

“I desperately hope that some sort of compromise or understanding can be reached before that happens,” he added, “but that requires people from both sides to talk to each other.”

Lillywhite and other outdoor advocates have asked the St. George City Council to create an open space and recreation preservation committee. The city supports the idea, St. George Mayor Jimmie Hughes told The Tribune.

“We’re going to put that energy to use to try to hopefully move the needle on Zone 6 so that we can preserve that in perpetuity, regardless of the lawsuit,” he said.

Hughes said he was “disappointed” in environmental groups’ lawsuit.

“There’s been a lot of compromise that’s been done and progress made on even setting aside more area for the desert tortoise habitat and open space and recreation,” he said. “So it’s really frustrating.”

How the desert tortoise may fare

The Northern Corridor, including associated construction and eventual traffic, would run through critical habitat for the desert tortoise in the reserve, according to the Fish and Wildlife Service.

That part of the reserve has a high density of tortoises and has already seen habitat degradation from wildfires and the spread of invasive species such as cheatgrass. The highway will cross around 275 acres of critical habitat and fragment an additional 2,343 acres of habitat south of the road. This may lead to the destruction of burrows and displacement, relocation, injury and killing of tortoises, according to the agencies.

“It’s just unconscionable that the Fish and Wildlife Service and the BLM that are supposed to be responsible for recovering the tortoise would do this kind of what seems like a backroom deal,” said Ed Larue, board member of the Desert Tortoise Council.

“Roads like this create a dead zone, and animals disappear,” Larue added.

The environmental groups’ lawsuit claims that federal agencies’ approval of the Northern Corridor violates the act that created the national conservation area, as well as various other bedrock environmental laws, such as the Endangered Species Act.

It also argues that the federal government violated the Land and Water Conservation Fund Act because the Northern Corridor would pave over lands in the reserve that the federal government purchased with “conservation money for conservation purposes,” said Kya Marienfeld, attorney with the Southern Utah Wilderness Alliance, a plaintiff in the lawsuit.

A spokesperson for the Bureau of Land Management said the agency did not “have a comment due to the ongoing litigation.”

Washington County is “confident that the federal agencies have complied with all laws and regulations to manage public lands consistent with the law and the public interest,” Jerry Jaeger, county attorney, said in a statement.

If the highway goes through, the Division of Wildlife Resources will work with UDOT, the county and federal agencies to minimize impacts, Faith Jolley, the division’s spokesperson, wrote in an email. This will include installing culverts to allow tortoises to travel underneath the road and fencing to prevent them from entering the roadway, she added.

When tortoises are encountered during construction, the division will be notified and tortoises will be relocated, Jolley said.

The addition of Zone 6, an area that has seen less wildfire, will also help “create and maintain genetic diversity for the desert tortoise,” Jolley wrote.

The desert tortoise is already struggling, though. Tortoises in the reserve experienced “higher than normal adult mortality” in 2025, according to the division, “likely driven by a prolonged drought in southwestern Utah.”

Marshall Topham, a former biologist for the reserve and professor at Utah Tech University, criticized the reapproval. He said in an email to The Tribune that building a highway through “the heart of the reserve” where a high density of tortoises reside “ignores biological reality.”

What the Northern Corridor means for traffic

Washington County and UDOT have been pushing for the Northern Corridor to solve current and projected traffic woes as the area grows.

“If you care about transportation and our air quality and not having just idling cars on the Boulevard and Red [Hills] Parkway as we hit traffic failure, then this is a victory, right?” Snow said. “We get a clean, smooth road to cut down time and bypass that bottleneck at the cut in the hill for I-15.”

The highway would provide another route to move traffic between the east side of the county to the west side, including communities like Ivins and Santa Clara and popular recreation spots like Snow Canyon State Park.

A study prepared in 2024 for the Dixie Metropolitan Planning Organization, which oversees transportation planning in Washington County, found that without the Northern Corridor, five street intersections would see significant to excessive delays by 2050.

The study also found that the Northern Corridor would increase total vehicle miles traveled in the area, as people can travel further in a shorter amount of time.

Speck Dempsey, a transportation planning firm commissioned by Conserve Southwest Utah to study the Northern Corridor, said that new roads create “induced demand” by encouraging drivers to take more trips, eventually building up traffic again.

The firm concluded that civic leaders need to acknowledge that “accommodating more traffic only leads to more traffic.”

UDOT is committed to continuing to push for the Northern Corridor alongside Washington County, Thornock said.

“This has been part of the regional transportation plan for decades,” he told The Tribune. “Our resolve is not dying, and we still know of its criticality to the movement of people and goods.”