It may be 2029, 2035, 2045 or another seemingly remote date, but someday the two functioning nuclear power plants at Millstone in Waterford will shut down, just as Unit 1 did in 1998.

The agreement reached this month by Millstone owner Dominion and the electric utilities Eversource and United Illuminating means, fortunately, that through 2029 the power station will have wholesale buyers for its power.

The agreement opens a 10-year window for Waterford, southeastern Connecticut and the state to start planning for the day when the nuclear power plants stop producing electricity and jobs. Waterford is already doing long-range planning for the slippage of revenues from its largest taxpayer — currently 32 percent of the town's property taxes — but the impact of Millstone on the region and the state goes well past town lines, including 1,500 jobs.

The Day would like to see preparations modeled on the coordinated response to the planned closure of the Naval Submarine Base in Groton in 2005. This is not that, of course; the base was saved and improved for a new era of submarines and crews. When Millstone's time comes, it will leave behind a huge plant that must be dismantled and, unfortunately, a storage facility for spent nuclear fuel rods that ought not ever to have been allowed to become permanent. Unlike successful base closures where host communities put former military installations to new use, most of Millstone's 500 acres would remain off limits.

That is, unless municipal, business, labor, and regional planning leaders were to join the state's energy, environmental and emergency managers to craft a model for reuse based on safe removal of spent fuel. The closing of plants around the country could perhaps build up a head of steam for persuading Congress to reactivate plans for permanent storage at Yucca Mountain in Nevada. Connecticut could lead the way.

Waterford First Selectman Dan Steward speculates that Dominion itself might rebuild on the site for some as yet unknown energy technology. At the very least, the goal must be just what it always has been: to ensure that multiple giant nuclear reactors remain safe neighbors, and without added cost to the public.

The agreement, which will start June 1 if it passes a review by PURA, the Public Utilities Regulatory Authority, by then, calls for Millstone to sell the Eversource and United Illuminating utilities 9 million megawatts of electricity per year, continuing to provide the lion's share of the state's power generation.

Connecticut's Low and Zero Emissions Renewable Energy Credit Program requires Eversource and UI to procure credits from producers of renewable energy. Typically, renewable energy costs the utilities more to purchase than natural gas. Dominion threatened to shut down Millstone early unless recognized as a renewable source and allowed to bid in the auction of those zero-carbon credits. With the help of local legislators, the company prevailed.

Dominion is not saying what price it has agreed to, but Gov. Ned Lamont said the new deal reduced the projected ratepayer increase by almost half, compared to what was expected after the award of credits at auction in December under his predecessor, Dannel P. Malloy. That's welcome news, although there will still be increases. The company could also benefit from a commitment signed by all six New England governors to confer about the market for "reliable and affordable energy," with specific mention of nuclear power's importance in winter, when other renewables could flag.

Not to be overlooked is the reason that Dominion was able to threaten its way into the zero-carbon auction to begin with: Connecticut has a statutory goal of reducing greenhouse gas emissions by 45 percent below 2001 levels. Nuclear power is still by far the state's largest producer of carbon-free electricity. Without Millstone, the state could face power shortages, would have to buy and burn more fossil fuels and would be unlikely to meet the goal.

By 2029, when the agreement would be due for renegotiation, Unit 2 willl be a mere six years away from its license termination date; Unit 3 would still have until 2045, if Dominion wants to keep it going. By then, a decade's worth of new technologies propelled by the growing urgency to reduce carbon emissions will have arisen. Use that decade well.

The Day editorial board meets with political, business and community leaders to formulate editorial viewpoints. It is composed of President and Publisher Timothy Dwyer, Executive Editor Izaskun E. Larraneta, Owen Poole, copy editor, and Lisa McGinley, retired deputy managing editor. The board operates independently from The Day newsroom.