New York Gov. Andrew Cuomo is supportive of nuclear power generation upstate, but has long said a facility 30 miles north of Manhattan is too close to the nation’s most populous city.

Mr. Cuomo will get his wish in 2021, as the Indian Point Nuclear Power plant in Westchester County will shut down its two nuclear reactors under an agreement New York State reached with plant owner Entergy, The New York Times first reported. At the same time, the state has authorized up to $7.6 billion in ratepayer-financed subsidies to keep three other aging nuclear plants operating upstate.

In one sense, the agreement to close Indian Point is part of a nationwide trend to close aging power plants critics have long said pose too many safety risks. California reached a similar agreement with the state’s largest utility provider early this summer to close the Diablo Canyon nuclear plant, about halfway between Los Angeles and San Francisco.

But the first new nuclear facility to come online in 20 years started to supply power to Tennessee homes in October, with construction also occurring on new reactors in the nearby states of Georgia and South Carolina. Efforts are also underway to bring nuclear power into the 21st century, with the testing of technology for facilities that are smaller, safer, and more efficient.

New York, then, mirrors the national debate over the efficacy of nuclear power and its effectiveness in both power generation and the transition to a clean-energy future, as the Christian Science Monitor’s Jessica Mendoza wrote in June.

The reality is that a battle still rages and may go on for some time. Some new reactors are being built. Some governors even in other politically liberal states are trying to save old reactors rather than scrap them. And though cheap natural gas may have called the economics of nuclear plants into question, environmentalists are divided over whether a nuclear phaseout would be wise. “I think the stakes are becoming higher as these closures are happening,” says Jesse Jenkins, a researcher at the Massachusetts Institute of Technology's Energy Initiative. “We have a pretty big decision to make as a country about whether or not we’re going to give up this source of power or to build on that foundation. That could be one of the biggest decisions we’ll have when it comes to our targets and climate goals.”

In New York, Entergy has agreed to close the first of Indian Point’s two reactors by April 2020 and the second exactly a year later.

The agreement, a source confirmed to the Times and the Associated Press, will resolve longstanding disputes between Entergy, a Louisiana-based utility company, and New York State. The state and Riverkeeper, an environmental group that has long fought Indian Point, have agreed to drop safety and environmental claims they previously filed with federal regulatory agencies against the nuclear plant that came online in the 1970s, according to the Times. Entergy, meanwhile, has agreed to make repairs and safety upgrades, as well as allow inspections into the plant starting this year.

Entergy and the New York Attorney General’s office have each signed off on the agreement, which would also approve Indian Point’s two reactor licenses for six years, which expired in 2013 and 2015. The governor’s office has not yet signed off on the agreement.

Cuomo and his father, Mario, a former New York governor, long opposed nuclear power around New York City. The younger Cuomo said as attorney general that Indian Point was a “catastrophe waiting to happen.” Following the Fukushima meltdown in Japan tied to a large earthquake there in 2011, Cuomo and Riverkeeper urged federal regulators to conduct a seismic hazard analysis of fault lines near Indian Point.

The move to close Indian Point would follow the shuttering of other plants across the country. In addition to the proposal to close the Diablo Canyon plant in San Luis Obispo, Calif., energy companies across the country pulled the plug between 2013 and 2014 on four nuclear power plants. In June, Exelon Corp. also announced plans to shutter two nuclear plants in Illinois by 2017 and 2018, respectively.

But the two reactors that straddle New York’s Hudson River supply about one-fourth of the electricity to New York City. It’s unclear if power sources such as hydroelectric from Quebec or renewables will able to make up that power.

The Cuomo administration also recently authorized billions worth of upgrades to three upstate nuclear facilities because, it said, nuclear power is necessary to transition the state to renewables.

There are currently 100 nuclear reactors (including the one that came online in Tennessee in October) in the United States, concentrated in 30 states, according to the US Energy Information Administration. Nuclear energy supplies about 20 percent of the nation’s power, while renewables – wind, solar, geothermal, biomass, and hydroelectricity – produce 13 percent combined.

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The Tennessee reactor – the Watts Bar Unit 2 – came online after more than four decades of intermittent construction.

This report contains material from the Associated Press.