"Collectively, the requirements of the permit require an unprecedented level of environmental protection and compensatory land conservation for the construction of a transmission line in the state of Maine," DEP said in a May 11 statement.
Requirements include limits on transmission corridor width, forest preservation, culvert replacement and vegetation management projects.
"In our original proposal we worked hard to develop a project that provided robust mitigation measures to protect the environment," NECEC Transmission CEO Thorn Dickinson said in a statement. "And through this permitting process, we now have made an exceedingly good project even better for Maine."
NECEC will be built on land owned or controlled by Central Maine Power. The 53 miles of new corridor on working forest land will use a new clearing technique for tapered vegetation, while the remainder of the project follows existing power lines.
Environmentalists said they agreed with the decision, and the mitigation measures state regulators took.
"Building new ways to deliver low-carbon energy to our region is a critical piece of tackling the climate crisis," CLF Senior Attorney Phelps Turner said in a statement. "DEP was absolutely right to impose significant environmental conditions on this project and ensure that it does not harm critical wildlife areas."
Once complete, Turner said the transmission line will allow the region "to retire dirty fossil fuel plants in the coming years, which is a win for our health and our climate."
The Massachusetts Department of Public Utilities in June 2019 advanced the project by approving contracts for the state's utilities to purchase 9,554,940 MWh annually from Hydro-Quebec. Officials said the project is expected to provide approximately 2% to 4% savings on monthly energy bills.
Total net benefits to Massachusetts ratepayers over the 20-year contract, including both direct and indirect benefits, are expected to be approximately $4 billion, according to the state's estimates.
NECEC "will also deliver significant economic benefits to Maine and the region, including lower electricity prices, increased local real estate taxes and reduced energy costs, expanded fiber optic cable for broadband service in Somerset and Franklin counties and funding of economic development for Western Maine," project developers said in a statement.