It’s before dawn on a recent July morning at Lazy Point in Napeague Bay, LI, and there is a slight chill in the air as the fishermen unload their boats into the water.

Dan Lester, a 12th-generation bayman, and his son Daniel, 14, are among those heading to sea to check their traps.

“This is the most sustainable fishing you’ll ever see,” Dan says as they begin hand-sorting the fish trapped in their nets, tossing whatever they can’t sell, including small spider crabs and stingrays, back into the ocean.

On a certain level, not much has changed for these New York baymen since the 1600s, when their ancestors came from places such as Kent, England, and were taught to fish by native Algonquin tribe members. But these East End fishermen fear it soon will.

They are up in arms over an agreement to build 15 massive windmills — each more than 650 feet tall, the height of Manhattan skyscrapers — off the coast of Montauk.

The giant structures — with wingspans as wide as football fields — would be constructed 35 miles out to create New York’s first offshore wind farm, only the second in the country.

The proposed $750 million South Fork Wind Farm is part of Gov. Andrew Cuomo’s clean-energy push to generate 50 percent of state electricity from renewable energy by 2030.

But the baymen — who are Bonackers, the local name given to a group of families who have fished there since the 17th century — worry that the project will devastate the area’s fragile ecosystem, ruining their livelihood.

“You don’t destroy the environment to save it,’’ said Bonnie Brady, executive director of the Long Island Commercial Fishing Association.

“Fishermen want renewable energy,” she added. “But it needs to be responsible.”

The project’s proponents “are industrializing the ocean floor in order to harness the wind and create a clean-power source. But what about the food?’’

Deepwater Wind, the company behind the plan, says it hopes to put the “steel in the water’’ within two years.

The firm is owned by D.E. Shaw & Co., a $35 billion Manhattan-based investment fund. The fund’s founder, David E. Shaw, has been a steady contributor to Cuomo’s political campaigns, donating at least $37,500 between 2006 and 2010, records show.

Deepwater has a tentative agreement with the Long Island Power Authority for the project that’s worth $1.625 billion over 20 years, according to the Office of the New York State Comptroller. As part of the plan, the company would get a one-time tax credit worth around $170 million, or about 23 percent of the project’s total cost, although to receive the maximum financial break, it must start by 2020.

Deepwater’s contract with LIPA has already won the approval of the comptroller and State Attorney General’s Office.

More approvals are needed at the federal and state levels, said Stephen Boutwell, a spokesman for the federal Bureau of Ocean Energy Management (BOEM). But observers say that given the way the wind is blowing politically, the additional OKs shouldn’t be too hard to obtain.

Before that happens, however, local resident Myles Berkman is among those who want the town of East Hampton to order its own environmental-impact study on the project. No one knows for sure about the effect the plan will have because no site-specific independent study has ever been conducted, opponents argue.

“What are the dangers? We just don’t know,” Berkman said.

The baymen say they have a pretty good idea.

The pile-driving needed to blast open the ocean floor to place necessary cable under the seabed and construct the windmills will cause permanent damage to marine mammals because of its sonar-noise levels, the fishermen worry.

“Pile-driving is like a giant hammer pounding into the ocean floor,” said Gary Cobb, a 12th-generation Bonacker.

Also, the electrical currents emitted from the 50-mile transmission cable connecting the windmills to land will deliver powerful electromagnetic pulses that could harm the fish and push them into deeper waters, the fishermen fear.

The windmills are “on top of some of the best fisheries on the Eastern Seaboard,” Cobb said.

Meanwhile, “There are lots of kids who play on the beach that will have a high-voltage cable running underneath it,’’ Berkman noted, referring to equipment that will be 30 feet underground, according to Deepwater.

In places along the seabed where the cable can’t be buried, it will be covered in concrete, which could sink boats and destroy the baymen’s handmade nets, the fishermen say.

In addition, the baymen claim, the windmills will be spread out a mile apart, making them dangerous to navigate around in bad weather.

“It will be difficult at best and catastrophic at worst for the trawler fleets to navigate the obstacle course that the wind farm will create,” Cobb warned.

But proponents hail the project as both an environmental and economic boon. The wind farm would generate around 90 megawatts of clean energy to power 50,000 homes, backers say.

LIPA spokesman Sid Nathan estimated that locals’ bills will increase an average of $1.19 a month over the 20 years of the contract.

“Offshore wind will continue to decline in cost as the industry develops and technology advances,” Nathan said. “The South Fork is in need of new sources of power … [that meet] LIPA’s renewable-energy goals. New York’s first offshore wind farm was the least cost solution to meet increasing electric demand and our clean energy goals.”

The town of East Hampton would receive an $8.5 million “gift’’ from Deepwater under the deal, of which local officials say they plan to use $1 million to improve water infrastructure in Wainscott, where contaminants were found in private wells, and $1 million for an “inshore fisheries resource assistance fund.”

And such off-shore wind projects could create 5,000 jobs for the state by 2030, said Alicia Barton, president and CEO of the New York State Energy Research and Development Authority.

Clinton Plummer, vice president of development for Deepwater Wind, insists the giant windmills will not harm fish or the fishing industry.

The BOEM “still has to do their own environmental study but have not [recorded] any problems so far” in other waters, said Plummer, noting that Deepwater installed five giant wind turbines — visible from Montauk beaches on a clear day — off Block Island, RI, the first of their kind in the country.

Cobb noted that the proposed South Fork Wind Farm turbines would be taller — by 52 feet — and that there would be 10 more.

Cuomo has added that, since the windmills would be so far off the coast, they won’t block the summering One Percenters’ multimillion-dollar views.

But local night-sky lovers still gripe that even East End star-gazing will never be the same, with the massive structures lighting up at night like pinball machines in order to avoid plane crashes, creating a mini-Manhattan in the middle of the ocean.

Nantucket and Martha’s Vineyard successfully fought off a $2.6 billion unrelated Cape Wind project thanks to high-profile naysayers such as the late Sen. Edward Kennedy and billionaire Bill Koch, both sailing lovers.

The baymen had hoped that the East End’s sea of summertime celebrities might likewise come to their aid in their uphill battle.

Much of the wild-caught seafood consumed in New York state — from cod, monkfish, sea bass, fluke and sea scallops to tuna — is harvested off Long Island, according to Brady’s association. Gwyneth Paltrow, Kim Cattrall and Alec Baldwin — or their chefs — regularly flock to sample the freshest catches of the day at Stuart’s Seafood Market in Amagansett.

But none of the rich and famous have yet taken up the protest.

“People don’t know our story or care,’’ Cobb lamented.

Last week, over the Long Island fishermen’s protests, the town of East Hampton agreed to provide easements for Deepwater Wind to lay cable under town land.

Councilman David Lys opposed the plan along with colleague Jeff Bragman, but lost out in the 3-2 vote.

Lys said Deepwater’s $8.5 million “gift’’ could be construed as a payoff for locals to keep their mouths shut about problems.

“I am fearful that my decision here will be seen as someone who does not look at the environment,’’ Lys said at the meeting, according to a local report. “But I’m also a protector of the values of the people who live here.”

Cobb said the vote was deflating.

“Everyone here has been here for 12 generations or more,’’ Cobb said of himself and the other baymen.

“These guys are content to come home after a day of fishing to build a fire and drink some beers. We just want to keep doing what we do,’’ he said.

“We are a very proud people, and it is very hard to witness this. The deck is stacked against us, but we still manage to survive.

“We hope there will be a next generation.”