Waterford — State regulators recently approved a 10-year contract between the owner of Millstone Power Station and utility companies, effectively ending the yearslong political, regulatory and environmental battles to keep the plant operational.

Gov. Ned Lamont, who stepped in earlier this year to help secure a deal between haggling Dominion Energy, Eversource and United Illuminating, applauded the finalized contract in a news release Wednesday.

“Had this contract not gone forward, the facility would be in danger of closing down, which would have increased greenhouse gas emissions by 25 percent across the New England region,” said Lamont, who recently pushed for all of the state’s energy to come from clean sources by 2040. “Now we can renew our focus on offshore wind and other renewable energy resources.”

The contract calls on the utilities to buy half the plant’s output over the next decade. The price per kilowatt hour in the contract has not yet been released to the public, according to Dominion spokesman Ken Holt. Department of Energy and Environmental Protection spokeswoman Kristina Rozek said pricing will be available 90 days after contract approval, unless Dominion chooses to release it sooner.

"Today's approval by PURA of the power purchase agreement between Connecticut's utilities and Millstone is great news for Connecticut, its residents, and the women and men who work at Millstone," Paul Koonce, Dominion president and CEO, said in a statement. "Approving the contract ensures that for at least the next decade, Millstone will continue to power 2.1 million homes with around-the-clock, carbon-free electricity while providing more than $1.5 billion of annual economic benefits to Connecticut."

Facing high maintenance and security costs and stiff competition from natural gas, Virginia-based Dominion had threatened to shutter the 2,100-megawatt Millstone unless the state let it compete against higher-priced solar, wind and hydropower. Nuclear plants in New York, Illinois and New Jersey have faced early retirement before lawmakers in those states approved subsidies. Dominion closed Kewaunee Power Station in Wisconsin in 2013.

Former Gov. Dannel Malloy and the General Assembly paved the way for nuclear to compete as a zero-carbon power resource with legislation supporting Millstone in 2017. The Department of Energy and Environmental Protection and PURA later found Millstone to be at risk of early retirement, a prospect that jeopardized more than 1,000 jobs and inspired regulators to make dire predictions about potential environmental, economic and grid reliability impacts.

Millstone’s competitors and many renewable energy advocates argued Dominion didn’t have to close the plant, which regulators had found to be profitable even in worst-case economic scenarios.

But DEEP selected power from Millstone in a zero-carbon request for proposals late last year, and PURA finalized the contracts on Wednesday.

"These next 10 years matter for fighting climate change and decarbonizing the electric grid," DEEP Commissioner Katie Dykes said in a statement. "DEEP is excited to be identifying pathways to achieve a clean energy grid as part of the governor's executive order to expand renewable and other clean energy resources in a way that is affordable and reliable."

State Rep. Kathleen McCarty, R-Waterford, said in an interview that nuclear power would serve as a bridge to renewable energy such as offshore wind.

But she added that she hoped Millstone "would be around longer than the duration of the contract. I think wind and solar are a great idea, but I don't think we should jump to the conclusion that it's going to be a panacea. We have to take this step by step."

b.kail@theday.com