New England’s last coal plant, Merrimack Station in Bow, N.H., will permanently stop operating in 2028 under a settlement agreement signed Wednesday. Jim Cole/Associated Press, file

BOSTON — The last coal-fired power plant in New England, which had been the focus of a lawsuit and protests, is set to close in a victory for environmentalists.

Granite Shore Power said Wednesday it reached an agreement with the Environmental Protection Agency to close the Merrimack Station in New Hampshire by June 2028. As part of the deal, the company said the site will be turned into the state’s first renewable energy park that host solar power and battery storage systems. The company also said it would shutter Schiller Station in Portsmouth in December 2025. That facility, which is permitted to use oil, coal and biomass, has not operated for several years.

“From our earliest days as owners and operators, we have been crystal clear; while our power occasionally is still on during New England’s warmest days and coldest nights, we were firmly committed to transitioning our facilities away from coal and into a newer, cleaner energy future,” Jim Andrews, CEO of Granite Shore Power, said in a statement. “By pursuing and ultimately entering into this voluntary agreement with the EPA, we are keeping that commitment.”

The 460-megawatt station in Bow has long been a thorn in the side of environmental groups. Most recently, the Sierra Club and the Conservation Law Foundation filed a lawsuit against plant owners, alleging it was violating the Clean Water Act. The plant was owned by Eversource until 2018 when it was sold to Connecticut-based Granite Shore Power. Both were named as defendants.

The environmental groups claimed the plant draws about 287 million gallons of water per day from the Merrimack River, heats that water as a result of its cooling process, and then discharges the water back into the river at temperatures that often exceed 90 degrees Fahrenheit.

Climate activists also protested the plant and demanded its closure over concerns it is a major source of air pollution. In one incident, climate activists last year paddled canoes and kayaks down the Merrimack River to the plant site and were arrested after going onto the property.

“This historic victory is a testament to the strength and resolve of those who never wavered in the fight for their communities and future,” Ben Jealous, Sierra Club Executive Director, said in a statement. “The people of New Hampshire and all of New England will soon breathe cleaner air and drink safer water.”

The Sierra Club said the announcement will make New Hampshire the 16th state that is coal-free and New England the second coal-free region in the country. Still, a majority of the region’s energy comes from natural gas. The main ingredient in natural gas is methane, a potent greenhouse gas that contributes significantly to global warming.

“Today’s announcement is the culmination of years of persistence and dedication from people across New England who knew coal was a dirty, expensive, and unreliable source of energy that would cut people’s lives short, and that a better way was possible for our economy, for our health, and for our planet,” said Gina McCarthy, Bloomberg Philanthropies Senior Advisor and former White House National Climate Advisor. “I am wicked proud to be from New England today and every day.”