The principal owner of the Wyman power station in Yarmouth has filed an appeal challenging a crucial permit awarded to Central Maine Power for its new transmission corridor.

Nextera Energy Resources filed an appeal of the permit issued by the Maine Public Utilities Commission on Tuesday. In its filing, the energy company alleges the PUC erred in awarding the permit because, among other things, it did not adequately consider alternatives to the 145-mile power corridor, and the PUC’s conclusion that the power line will provide benefits to Maine was not supported by substantial evidence.

The permit, awarded April 11, is the first of several approvals CMP needs to build its $1 billion New England Clean Energy Connect transmission corridor. The project is intended to bring electricity generated by hydro power in Quebec to markets in Massachusetts.

But it has been contentious, dividing opinions among environmental organizations, economic development groups and municipalities. In February, Gov. Janet Mills signaled her support of the project after CMP offered $258 million in benefits, including $140 million fund to help lower electric rates and a separate $50 million fund for low-income customers, paid over 40 years. Also in the package were $15 million for heat pump installations; $15 million for electric vehicle charging stations; $5 million for communities along the power line route; and $15 million for high-speed internet service and fiber optic cable.

Opponents of the project pledged to turn their attention to other regulatory bodies that need to sign off on the project, including the Maine Department of Environmental Protection and the Land Use Planning Commission.

“We are not surprised that an appeal was filed. Each day that this project is delayed means another $3 million dollars lines the pockets of dirty fossil fuel generators,” Thorn Dickinson, vice president of business development at Avangrid, CMP’s parent company, said in a statement Tuesday night. “As the most important clean energy project to ever come to Maine, New England Clean Energy Connect is a major change in the status quo of Maine’s energy market, threatening these interests.”

NextEra and other Maine power generators have opposed the power line, saying the hydropower provided by Quebec is “subsidized energy infrastructure.”  Their holdings include natural gas and oil-fired power plants that stand to lose millions of dollars in revenue if the transmission line is built.

NextEra Energy, based in Juno Beach, Florida, is the parent company of NextEra Energy Resources. With its affiliates, NextEra is the world’s largest generator of renewable energy from wind and solar sources, and a world leader in battery storage.