Power from the long-awaited New England Clean Energy Connect transmission line will begin surging from Québec to Massachusetts on Friday, the company Hydro Québec confirmed.

The New England Energy Connect (NECEC) line, a project initiated in 2017 under the Baker administration, has faced years of regulatory hurdles and political battles but is now set to become one of the region’s largest sources of baseload power.

After five years of construction, the transmission line’s “Commercial Operation is scheduled to commence on January 16, 2026, unless the parties — NECEC, the Massachusetts Electric Distribution Companies, and Hydro-Québec — mutually agree in writing to an alternative date,” a biannual progress report filed with the Maine Public Utilities Commission states.

“We have successfully completed the testing phase of the new transmission line and are expecting to begin deliveries to Massachusetts this Friday,” a spokesperson for Hydro Québec confirmed Thursday. “After several years of hard work, we are very excited about this significant milestone.”

The NECEC line will deliver 1,200 megawatts of hydropower from Québec to New England over 20 years, according to the project. The Canadian hydropower is expected to deliver Massachusetts about 20% of its overall electricity.

Avangrid, the parent company behind the NECEC, announced it had secured the final permit to get the project running in November, estimating at the time the line would begin operations by the end of 2025. In early January, Hydro Québec reported work on the project would be complete within the month.

The clean energy line, which was estimated to cost around $1 billion, is expected to deliver about $3 billion in net benefits to Massachusetts energy customers and overall reduce “ratepayer bills by around $50 million each year,” according to state officials. The savings come out to an average of about $18 to $20 for residents over the contract term.

Gov. Healey called the line a source of “affordable, stable power” in a November release, heralding the project as key to reducing greenhouse gas, meeting the state’s rising electricity demand and providing energy reliability in the winter.

Avangrid has estimated the project will cut carbon emission by 3.6 million metric tons a year, “the equivalent of removing 700,000 cars from the road.”

In Maine where much of the line was constructed, the project faced heavy opposition and a 2021 referendum, during which voters elected to axe the project. The Maine Supreme Judicial Court eventually struck down the vote and allowed the project to continue. In early 2025, the Massachusetts Department of Public Utilities announced a final settlement for the project completion.