Gov. Cuomo keeps blocking natural-gas pipelines in New York, supposedly because they might taint rivers and streams. But a new report flags the real reason: The mere use of natural gas is too much for enviro-radicals.

The study, by Physicians, Scientists and Engineers for Healthy Energy for the group Earthworks, argues that OK’ing new or upgraded pipelines and other infrastructure will let gas consumption increase — and thereby boost emissions of CO2 and methane, making it impossible to meet Cuomo’s goal to reduce greenhouse-gas emissions.

The study looks at new gas projects, which it figures would add up to 31 million tons a year in emissions. That would put “the state’s 2030 goal . . . virtually out of reach,” says co-author Elena Krieger.

Cuomo’s goal for 2030 is to trim NY emissions to 40 percent below their 1990 level. To do that, he’s pushed renewable energy, like solar and wind — but also says switching from oil and coal to (cleaner) natural gas is critical. “I think in all probability you need natural gas,” he said last year.

He’s right: New York has already cut emissions to 13 percent below 1990 levels, mainly by substituting gas for oil and coal. Gas supplies from Pennsylvania alone jumped sevenfold from 2007 to 2016. (New York can’t tap its own vast stores of natural gas, thanks to Cuomo’s fracking ban.)

Yet the green extremists want more: “Cuomo can either work to achieve his climate commitments or support new natural-gas infrastructure, not both,” insists Earthworks’ Nadia Steinzor.

And never mind that several pipelines merely cross the state to supply New England and Canada.

To date, the governor’s Department of Environmental Conservation has been doing just what the extremists want, nixing pipelines large and small — and even going to court when overruled by the feds. Industry insiders call it the “Wall of Cuomo.”

Mind you, the DEC lacks the legal power to block pipelines over climate-change issues, so it instead invents spurious fears of “water-quality impacts.”

It has even blocked pipelines to feed the power plants that Cuomo says will replace the capacity that New York’s losing after he forced the early shutdown of the Indian Point nuke plant.

Already, New York and New England import more-expensive foreign gas to cover nearly a fifth of their heating and electric needs, even though the United States is now a net exporter of gas.

All this drives up consumers’ costs, making New York even less competitive with other states.

Cuomo plainly figures he can get away with it. In a pinch, he’ll just blame Con Ed.