MASSENA -- The New York Power Authority will spend more than $70 million to replace transmission lines connecting Massena and Plattsburgh with Crogan and Milton, Vt.

The Massena project is the first phase of SMART Path, the replacement of the New York Power Authority’s Moses-Adirondack transmission lines.

The lines run 85 miles from Massena, home to the St. Lawrence-FDR hydroelectric plant, to a substation in Croghan, Lewis County.

The 230 kV lines were built by the federal government in 1942 and were acquired by the New York Power Authority in 1953.

The route for all but eight miles of the lines travels on outmoded wooden structures that need to be replaced periodically. The new 230 kV lines on steel structures will sit on concrete foundations. All construction is expected to be on the existing right-of-way in order to minimize the impact on the environment and adjacent property.

NYPA trustees ratified a $2.76 million contract with Louis Berger & Associates, P.C., a New York firm, to shepherd the licensing review, which is expected to take about two years.

Construction on the line is slated to begin in 2018 and last until 2023. When completed, technological improvements that are part of SMART (Strengthening Moses-Adirondack with Resilient Technology) Path will ensure an uninterrupted supply of electricity on high-demand days.

NYPA also approved a $68 million replacement of transmission cables that connect a New York Power Authority substation in Plattsburgh to a substation in Milton, Vt., owned by the Vermont Electric Power Co. The line is capable of two-way transmission so one utility could bolster the other’s supply on peak demand days. Vermont Electric will help pay for the project.

The work includes the design, fabrication and installation of new terminal structures at the substations as well as the replacement of 1.7 miles of cables along the bottom of Lake Champlain. Four new cables are being installed to replace some that were originally installed in the 1950s and 1970s. The new cables can support increased energy demand and will have fiber-optic capability for current and future communications needs.

Gov. Andrew M. Cuomo says the projects will be a boon to the North Country’s power grid.

“These projects will help create a modern, more reliable and more resilient power grid for the North Country and New York as a whole," Gov. Cuomo said. "This administration has taken significant steps to rebuild this state’s energy infrastructure and we remain committed to creating one of the most innovative power grids in the country."