PIERRE, S.D. - The South Dakota Supreme Court has upheld a state commission's decision to grant a construction permit for the Big Stone II power plant that a coalition of utility companies plans to build on the Minnesota-South Dakota border near Milbank.

The high court said the South Dakota Public Utilities Commission followed all laws in approving the permit and deciding the coal-fired power plant would not increase emissions of carbon dioxide by enough to seriously injure the environment.

Some environmental groups had argued that the PUC made a mistake because evidence showed carbon dioxide emissions will harm the environment.

"Our review of the record shows the PUC entered a well-reasoned and informed decision when it concluded that Big Stone II would not pose a threat of serious injury to the environment," Justice John K. Konenkamp wrote for the Supreme Court.

The utility companies originally planned a 630-megawatt facility, but they have revised their plans and now propose a coal-fired plant of 500 to 580 megawatts. Big Stone II would be built next to the existing Big Stone plant.

The five remaining partners in Big Stone II include Otter Tail Power Co. of Fergus Falls, Minn.; the Central Minnesota Municipal Power Agency of Blue Earth; Heartland Consumers Power District; Missouri River Energy Services; and Bismarck, N.D.-based Montana-Dakota Utilities Co.