A federal judge has ordered the Tennessee Valley Authority to clean up pollution from four coal-fired power plants that are affecting air quality in North Carolina -- but the ruling allows the federally-owned company to continue dirty business as usual at its other coal plants.

The decision [pdf] comes in a lawsuit North Carolina Attorney General Roy Cooper filed against TVA in 2006. The suit charged that air pollution coming from the company's smokestacks was hurting the health of North Carolina residents, obscuring mountain views and damaging forests.

"I'm pleased that the court ordered the TVA to clean up the air pollution coming from its plants closest to North Carolina," Cooper said. "This will help our air, our health, and our travel and tourism economy."

The ruling issued yesterday by U.S. District Court Judge Lacy Thornburg in Asheville, N.C. orders TVA to clean up emissions from four of coal-fired power plants within 100 miles of North Carolina: Widows Creek in northeast Alabama; Bull Run near Oak Ridge, Tenn.; John Sevier near Rogersville, Tenn.; and the Kingston plant in eastern Tennessee's Roane County, where the disastrous coal ash spill occurred last month.

But the decision denied North Carolina's request for better controls on air emissions from seven other TVA coal plants: Allen near Memphis; Colbert in northwest Alabama; Cumberland northwest of Nashville; Gallatin in middle Tennessee; Johnsonville near Waverly, Tenn.; Paradise in western Kentucky; and Shawnee northwest of Paducah, Ky. Thornburg ruled that these facilities were too far from North Carolina to significantly impact the state's air quality.

By forcing the company to internalize costs that it now externalizes, the decision will prove expensive for TVA, which is already facing an enormously costly cleanup of its Kingston ash spill. North Carolina's experts estimated that the total changes it sought would cost the company $3 billion, while TVA's experts put that figure at $5 billion. Thornburg told the Asheville Citizen-Times that the improvements he ordered at the four plants would cost about $1 billion, though some of the work is already underway.

While the requirement that TVA do a better job of cleaning up those four plants will help reduce air pollution, it's going to increase the amount of waste left over after coal is burned -- the very stuff that spilled from the Kingston surface impoundment and from another impoundment at Widows Creek earlier this month.

This makes it even more urgent for TVA to improve the way it handles coal combustion waste -- and for the federal government to provide adequate regulatory oversight of that waste.

(Photo of the Kingston power plant from TVA's website)