The 10th Circuit Court of Appeals on Monday stopped the construction of Gov. Mike Leavitt's Legacy Highway, overturning the federal government's approval of the project.
The Denver-based court found that the Army Corps of Engineers failed to adequately consider the harm the highway would have on wildlife when it issued a permit for the highway construction.
After reviewing the environmental impact statement, the court said "the indirect impact on wetlands analysis is not adequate to the point of being arbitrary and capricious."
The court also found a failure to consider mass transit, failure to seriously consider alternative routes, and failure to consider a narrower median, the ruling said.
Leavitt said the project has not been killed by the ruling, describing the court's findings only as a setback.
"We are committed as a state to finding the responsible solutions to our transportation problems. Any rumors of Legacy's death are greatly exaggerated," Leavitt said. "As I indicated, there is a great need for this road."
The Sierra Club, Salt Lake Mayor Rocky Anderson and others had sued to stop the first portion of the highway, claiming it would violate federal clean water standards. Monday, they were hailing the ruling.
"While transit is crucial to solving our long-term problems, we are not against all roads," said Bob Adler, attorney for Utahns for Better Transportation. "Well-planned roads that do not destroy wetlands or promote sprawl are part of a balanced transportation system."
Mayor Anderson said the ruling will benefit all Utah residents.
"There are those who are not going to feel they are victorious today. But this is a victory not only for the environment, it is indeed a victory for the rule of law."
Those who filed the lawsuit said Monday's ruling will force the state back to the bargaining table to consider alternative options to ease traffic, including mass transit.
Meanwhile, the executive director of the Utah Department of Transportation said the ruling will mean more traffic jams.
"We are disappointed with the ruling because of the effect it could have on residents and commuters in northern Utah," said John Njord.
The five-panel appeals court had already stopped construction of a 14-mile highway segment in Davis County last November pending Monday's ruling.
That work stoppage has cost the state $17 million through a combination of contractual obligations and court costs, Njord said.
Leavitt — faced with estimates that Utah's population will increase 71 percent in the next 30 years — had thrown his weight behind the Legacy Highway, which would span 125 miles from Brigham City to Nephi.
The first section of the project, called the Legacy Parkway, ended in the lawsuit because it would have required paving over Great Salt Lake wetlands.
The 14-mile parkway was meant to serve as a bypass to I-15 in Davis and Salt Lake counties.
"There will be no need to go back to square one. Those things we've done right, we'll build on those and move forward," Njord said.