PITTSBURGH - Despite its ranking as the state's top polluter, AK Steel Co. has been lauded by the U.S. Environmental Protection Agency for reducing water pollution at its Butler Works.

The plant, about 30 miles north of Pittsburgh, ranked third among the nation's biggest water polluters in 2001, down from the country's worst in 2000, according to a recently released EPA report.

By changing the way it cleans steel, the plant had a 72.9 percent reduction in the amount of chemicals discharged into the Connoquenessing Creek from 2000 to 2001. The discharges are legal.

"This is a major improvement, and they did this by changing the way they clean the steel," said Bill Reilly, the EPA's toxic release inventory coordinator.

Myron Arnowitt, western Pennsylvania director of Clean Water Action, which pushed AK Steel and federal regulators for changes, called the company's efforts "a great solution."

Middletown, Ohio-based AK Steel bought the plant in 1999 and spent $25 million to convert to a different steel-cleaning system, said spokesman Alan McCoy.

McCoy said the changes put the company at a competitive disadvantage. He said there was no scientific evidence linking nitrates, which had been used in the old cleaning process, to health or environmental problems.

High levels of nitrates can cause serious illness and even death, especially in infants.