Eversource has notified the state that it plans to power up its new Seacoast transmission line at the end of this month, on May 29.
The Seacoast Reliability Project runs about 13 miles between Madbury and Portsmouth, with a mile buried underwater beneath Little Bay, between Durham and Newington.
Eversource proposed the project in 2015 as part of its response to a call for more reliable infrastructure from the regional grid operator, ISO-New England. The utility says the line will help carry electric load and back up other transmission lines in the area.
The project won state approval in late 2018. It was the second such reliability project Eversource got certified in recent years, and came on the heels of the surprise denial of the utility's major Northern Pass proposal.
The Seacoast project faced a series of court appeals, mostly related to its potential effect on Great Bay. Those cases have now mostly moved into settlement phases.
After the main power line goes online, an Eversource spokeswoman says the utility will still need to power up a distribution line in Madbury and continue restoring wetlands and vegetation in the project's right of way. That work will last into early summer.