Minnesota has officially approved power lines to bring electricity into the state from a planned expansion of the coal-fired Big Stone plant.
Big Stone II will be built in South Dakota, but it's not economically feasible without power lines into Minnesota.
The Minnesota Public Utilities Commission's approval notice includes several conditions. The agency is limiting the amount of construction costs and future carbon costs that Otter Tail Power, the project's main partner, can recover from ratepayers.
Environmental groups have charged that the five utilities have low-balled those costs to get approval.
The project also faces a challenge from the federal Environmental Protection Agency, which says South Dakota isn't requiring enough pollution control.
South Dakota regulators have until the end of April to respond.