A Superior Court judge ruling’s Wednesday may have created another hurdle for the builders of a 145-mile energy transmission corridor through northwestern Maine.

Justice Michaela Murphy ruled that the Maine Bureau of Public Lands did not have the authority to lease public reserve lands to CMP affiliate NECEC Transmission LLC, which is building the corridor, without first determining whether the lease would substantially alter the land in question. If a review finds the state-owned land would be significantly altered because of the lease, the question would go to the Legislature, Murphy ruled.

Wednesday’s ruling came in a civil action filed by state Sen. Russell Black of Wilton against Andy Cutko, director of the Maine Bureau of Public Lands.

The land in question is a mile-long section about 300 feet wide in the West Forks area of Somerset County through which the corridor would pass. The lease was renewed by the state and CMP in June 2020 for 25 years, according to a copy obtained by Maine Public. BPL will receive $65,000 a year in lease payments.

Murphy ordered BPL to conduct a formal assessment of the impact on the land, and a two-thirds majority of both the state House and Senate would have to approve it if the review finds significant alterations would occur.

The NECEC project would transmit 1,200 megawatts of hydroelectricity from Canadian utility Hydro-Quebec to the New England grid, and would be funded by Massachusetts ratepayers. The transmission corridor would cut through about 53 miles of mostly-commercial forest owned or controlled by CMP in western Maine before following existing transmission corridors. Crews are already widening existing portions of the corridor.

CMP says the completed project will both cut greenhouse emissions and lower energy costs in Maine and New England.

But the project has had its share of critics and opposition. Sen. Black and Cutko were unavailable for comment Wednesday evening.

In her ruling, Justice Murphy said the Maine Constitution does not allow state-owned public lands to be “substantially altered” without approval from two-thirds each legislative branch. Murphy ruled that the BPL should have conducted a review before it leased the lands to CMP.

An amendment to the Maine Constitution, adopted in 1993, includes the following restriction on BPL’s authority over public reserved lands: “that public reserved lands cannot be reduced or their uses substantially altered except on the vote of 2/3 of all the members of each house,” Murphy wrote in her opinion.

“Substantially altered” means changes in the use of designated lands that significantly alter its physical characteristics in a way that frustrates the essential purposes for which that land is held by the state, Murphy said.

Murphy sided with Sen. Black, noting that there is no explicit exemption made for any type of property conveyance by the state, such as for an easement or lease. The BPL argued that certain uses are exempt from the constitutional provision.

It was not clear Wednesday what, if any, impact Murphy’s ruling would have on the progress of the project, but a spokesman for CMP said members of the NECEC project were reviewing the decision.