The lattice towers Central Maine Power said it is proposing for its New England Clean Energy Connect hydropower line from Canada to Lewiston. This image, looking northwest from Wilson Hill Road in West Forks Plantation toward the proposed transmission line, also contains a photosimulation of five years of vegetation growth that is 10 feet or less in height. Credit: Courtesy of Central Maine Power

Another potential barrier to Central Maine Power Co.’s proposed $1 billion hydropower corridor through western Maine was removed Tuesday when the Maine Supreme Judicial Court ruled against a challenge to a regulator’s approval of the project.

In a case filed last fall, NextEra Energy Resources appealed the certificate of public convenience and necessity that the Maine Public Utilities Commission granted last April for the controversial project.

The project needs a series of regulatory approvals. Last Friday, the Maine Department of Environmental Protection became the latest agency to give preliminary approval to the project.

The controversial hydropower project, which would extend 145 miles from Hydro-Quebec’s dam system at the Canadian border through western Maine to Lewiston, also needs from the Army Corps of Engineers a presidential approval to cross the border and town permits.

NextEra isn’t the only one trying to halt the corridor. Say No to NECEC, a grassroots group opposed to the corridor, has delivered enough signatures to the secretary of state’s office to set up a likely November referendum against the utility. A CMP political action committee is reviewing the signatures.

NextEra argued in its appeal that the public utilities commission failed to require CMP to file results of an independent investigation into the use of nontransmission alternatives.

The company also alleged that the commission failed to take into account certain statutory criteria when it determined whether the electric corridor was a public necessity.

It said the commission erroneously let the Department of Environmental Protection and the Land Use Planning Commission decide on how to mitigate the adverse effects of the project on scenic and recreational resources.

Finally, it said the commission was not unanimous in its approval of a stipulation that added benefits to the CMP proposal.

In its ruling, the court said the commission followed the proper procedure and “reasonably interpreted and applied the relevant statutory mandates” in arriving at its decision to grant the certificate and to approve the stipulation.

“NextEra has not shown that the commission’s issuance of the [certificate] or approval of the stipulation was arbitrary or otherwise based on an error of law,” the court wrote. “The order of the public utilities commission is affirmed.”

A NextEra spokesperson was not immediately available for comment.

Lori Valigra, investigative reporter for the environment, holds an M.S. in journalism from Boston University. She was a Knight journalism fellow at M.I.T. and has extensive international reporting experience...