Steve Flint, a board member for the nonprofit, said the group’s concerns have not been quelled since members last took legal action against the state in 2003.

“One of the biggest concerns is that the eastern route that they proposed is closest to the prairie remnants,” he said.

In March, the Idaho Transportation Board unanimously approved the eastern route alternative for the 6.34-mile stretch of highway, and the formal record of decision was published in April in the Federal Register. The project will expand the highway from two to four lanes, including a 34-foot median and center turn lanes, as well as curbs, gutters and sidewalks at the northern end of the project, just south of Moscow.

The eastern alignment, one of three options considered, is nearest to Paradise Ridge. The area contains some of the last remnants of the Palouse Prairie, Flint said, including the endangered Spalding’s catchfly.

The lawsuit argues environmental damages caused by the eastern route, along with mitigation efforts, have not been adequately analyzed.

The route will influence 3.62 acres of wetlands, according to the lawsuit, which have already been “significantly impacted” by past development.

“Even minor impacts to wetlands can have severe consequences for wildlife and water quality within the region,” according to the lawsuit.

The proposed construction will also reportedly disturb more ground than alternate routes, making “the ground more susceptible to weed invasion which can choke out the native grasses and flowers of the Palouse Prairie remnants,” according to the suit.

Transportation department spokesman Adam Rush said the environmental impact statement was completed with input from multiple sources and takes into consideration the environment, terrain, residences and businesses along the route.

“We do a thorough environmental review when we’re planning our highway projects,” Rush said.

Rush said the state received a copy of the lawsuit Friday.

“We understand that that’s an option that’s open to the public,” Rush said. “… Our goal is to do a thorough job in the planning and development of our projects to answer and address as many concerns as we can.”

The highway realignment project is still on track for construction to begin in fall 2017, Rush said. It is expected to be completed during the summer of 2019.

Rush said safety is the state’s primary objective for every highway project.

“The proposed route is designed to create a new highway section that’s safe,” Rush said.

The lawsuit argues the state has not adequately disclosed predicted traffic collisions, and that the environmental impact statement also fails to consider wildlife-related accidents or the potential effects of adverse weather.

The higher elevation of the eastern route “will result in more snowfall accumulating,” according to the suit, and “marked differences in the amount of fog.” There is “no persuasive evidence that the chosen route will be any safer than any of the alternatives, yet all of those alternatives would cause less environmental harm.”

The suit alleges alternate routes have not been adequately examined, including the central route the Paradise Ridge Defense Coalition prefers. The central route utilizes much of the current roadway and is farther west from Paradise Ridge than the eastern route, Flint said.

Flint said the state could have taken steps in recent years to improve the existing roadway, like implementing centerline rumble strips.

“It’s unfortunate they didn’t take some of those kind of actions in the intervening years,” he said. “Nobody’s really pushing for delay.”

(By Chelsea Embree, Lewiston Tribune)