ST. CLAIRSVILLE, Ohio — The largest environmental settlement involving the U.S. government was approved this morning by District Court Judge Edmund A. Sargus Jr. near several power plants affected by the deal.

The federal government, eight states and 13 environmental groups signed off on the agreement with American Electric Power. The Columbus-based company will begin reducing sulfur dioxide and nitrous oxide emissions at 16 power plants east of the Mississippi.

The emissions will be reduced from about 1 million tons annually to 246,000 tons by 2019, according to the settlement.

Ohio rate payers already have been funding the installation of scrubbers and other equipment with a $2 to $3 increase in their monthly bills. The increase was approved by the state Public Utilities Commission last year.

The total cost of pollution controls will be $6.6 billion, AEP said.

In Ohio, the Cardinal, Conesville, Muskingum River, Gavin and Picway power plants will be affected. The U.S. EPA, states and environmental groups filed lawsuits in 1999, claiming that AEP and other power companies had violated the federal Clean Air Act.

The settlement was announced in October.

kmayhood@dispatch.com