The state has ordered the contractor for the New England Clean Energy Connect project to clear crane mats and trees it previously cut from parts of the planned 145-mile power line corridor between Quebec and Lewiston.

The Maine Department of Environmental Protection said Monday that the downed trees must be out of the corridor before winter, along with the mats that were placed to support construction cranes. If the trees and mats aren’t removed in time, the project will no longer be in compliance with its permit.

Timbers used to build the mats that support construction cranes are stacked alongside the NECEC corridor in Johnson Mountain Township in November 2021. The DEP says more than 36,000 crane mats and 20 miles of vegetation must be removed or chipped and spread by Dec. 14. Gregory Rec/Staff Photographer

The department noted that its order suspending the NECEC permit – issued last November, shortly after voters approved a referendum blocking the project – called for cut vegetation to be removed or chipped and spread. Removing the material before the ground freezes will help areas where construction took place to revegetate more quickly, the DEP said.

More than 36,000 crane mats need to be removed and more than 20 miles of vegetation must be removed or chipped and spread, according to the DEP.

Cleanup of one section was due to start Monday, and the cleanup of the final section is due to be completed by Dec. 14.

The DEP’s order said that requiring NECEC to remove the mats and the cut vegetation is narrowly tailored to those two tasks and doesn’t allow NECEC to restart construction work for the transmission line.

NECEC began construction on the corridor last year while groups collected signatures to put the measure stopping the work on the fall ballot. Voters approved the measure, but NECEC filed suit seeking to block its implementation while continuing work on the project.

The work eventually halted late last fall after the DEP withdrew the permit in light of the referendum. Gov. Janet Mills also asked officials with Avangrid Inc., the Connecticut-based parent company of both NECEC and Central Maine Power Co., to halt work while the lawsuit was pending.

In late August, the Maine Supreme Judicial Court ruled that the referendum is unconstitutional if NECEC proves it had put enough money into the project to establish “vested rights.” The case was sent back to the state’s Business and Consumer Court to determine if NECEC has those rights and a trial is scheduled for April.

The Supreme Judicial Court has yet to rule on another challenge to the project, contending that NECEC does not have a valid lease on a section of the corridor that crosses state land.

The transmission line would carry hydroelectricity generated in Canada to a connection to the New England power grid in Lewiston. The work is being paid for by Massachusetts utilities and the electricity would go to Massachusetts customers.