The Arkansas Public Service Commission has approved the installation of additional environmental controls at the Flint Creek Power Plant in Gentry.
Wednesday's decision comes in response to a request by Southwestern Electric Power Co.
SWEPCO and the Arkansas Electric Cooperative Corporation each own 50 percent of the coal-fueled plant in northwestern Arkansas.
SWEPCO says it expects construction to begin in January, pending approval of environmental permits.
The $408 million project includes installation of controls for sulfur dioxide, nitrogen oxide, mercury and other hazardous air pollutants to comply with new Environmental Protection Agency regulations.
SWEPCO provides power to 113,700 retail customers in western Arkansas AECC provides wholesale electricity to Arkansas' 17 electric cooperatives that have almost 500,000 customers in Arkansas.