The new national grasslands plans ignore one potential impact entirely: The nation’s largest railroad construction project in more than a century.

The Dakota, Minnesota & Eastern Railroad got a green light last year from the federal Surface Transportation Board to build a 280-mile rail line that would cross the Buffalo Gap National Grassland in South Dakota and Thunder Basin National Grassland in Wyoming. The project also includes rebuilding 600 miles of existing track. The Minnesota-based railroad wants to compete with two other railroads hauling Wyoming coal to power plants.

During a five-year evaluation of the project, the Transportation Board imposed 134 conditions on the company — "the entire gamut, (covering concerns) about land use, water use, endangered species, archaeological and historic sites," says Ray Gigear, project engineer for the railroad.

But opponents — including Wyoming ranchers, the Sierra Club, cities along the route, and the Mayo Clinic in Rochester, Minn. — are fighting the railroad by suing the Transportation Board in federal court.

The railroad is "an industrial development that doesn’t belong in the grasslands," says Nancy Darnell, who leads the Mid-States Coalition for Progress, one of the plaintiffs. Darnell, whose ranch is woven into Thunder Basin grassland, says the railroad would take some of her land by eminent domain. Several other railroad lines already cross the Thunder Basin grassland, and Darnell says that’s more than enough.