A California judge on Thursday rejected an environmental group’s lawsuit that sought to block the state’s largest utility from seeking to extend the operating life of the Diablo Canyon Nuclear Power Plant.

Friends of the Earth sued in state Superior Court in April, hoping to derail a state-backed proposal to keep the twin-domed plant running for at least five additional years. The group was part of a 2016 agreement with operator Pacific Gas & Electric to shutter the state's last nuclear power plant by 2025.

Amid concerns over power supplies in a changing climate, Democratic Gov. Gavin Newsom and the Legislature opened the way for PG&E to seek a longer lifespan last year. In legal filings, the environmental group argued that the 2016 deal to close the reactors “is not fully extinguished,” and that the utility would break what it called a binding contract if it asked federal regulators to extend the operating licenses.

In an 18-page ruling, Judge Ethan P. Schulman dismissed the complaint, agreeing with the company that Friends of the Earth was asking the court to “impermissibly hinder or interfere” with state regulatory oversight of the seaside plant, located midway between San Francisco and Los Angeles.

If the group's request was granted, the court would be placed in conflict with state regulators, and it would “enmesh the court in complex questions of energy, economic and environmental policy” that are best handled by the California Public Utilities Commission and other agencies, Schulman wrote.

The group said it might appeal.

“The fight to shutter Diablo Canyon is not over,” Hallie Templeton, legal director for Friends of the Earth, said in a statement. The group has a separate case pending in federal court involving regulatory issues tied to the plant's operation and possible extension of the licenses.

In a statement, PG&E spokesperson Suzanne Hosn said the company is following California energy policy “and our actions toward relicensing Diablo Canyon Power Plant are consistent with the direction of the state."

The operating license for the Unit 1 reactor expires next year, and the Unit 2 license expires in 2025. The company intends to apply to the Nuclear Regulatory Commission by the end of the year to extend operations by as much as two decades.

California is the birthplace of the modern environmental movement and for decades has had a fraught relationship with nuclear power, which doesn’t produce carbon pollution like fossil fuels but leaves behind waste that can remain dangerously radioactive for centuries. The Newsom administration is pushing to expand solar power and other clean energy as the state aims to cut emissions by 40% below 1990 levels by 2030.

Newsom’s decision last year to support a longer operating run for Diablo Canyon shocked environmentalists and anti-nuclear advocates because he had once been a leading voice for closing the plant.

The lawsuit represented another mile-marker in a long-running fight over the operation and safety of the decades-old plant, which Newsom says should keep running beyond 2025 to ward off possible blackouts as California transitions to solar and other renewable energy sources.

Diablo Canyon produces 9% of the state’s electricity.

At this juncture, it’s not clear if the reactors will continue operating beyond the expiration of their licenses in 2024 and 2025 — and if so, for how long — since many regulatory and legal hurdles remain.

For example, it’s not yet publicly known what it will cost to update the plant for a longer run given that PG&E was preparing to close it for years. The state could consider backing out if capital costs climb over $1.4 billion - the amount of a forgivable loan the state authorized for PG&E last year as part of the legislative plan to keep the reactors running.

Construction at Diablo Canyon began in the 1960s. Critics say potential earthquakes from nearby faults not known to exist when the design was approved could damage equipment and release radiation. One fault was not discovered until 2008. PG&E has long said the plant is safe, an assessment the NRC has supported.

The U.S. nuclear industry has been through a tough stretch, with reactors retiring and its share of energy production slipping since 2012. But many industry leaders see a renaissance on the horizon, as climate change has brought attention to carbon-free power.