Freeport’s mayor is endorsing a proposal to build tidal gates along the South Shore of Nassau County to end flooding and save communities from damage in the next major storm.

In a presentation to local government officials during the Vision Long Island Smart Growth Summit in Woodbury on Friday, Mayor Robert Kennedy described an idea to add tidal gates at the entrances to the barrier island that includes the communities of Long Beach, Atlantic Beach, Lido Beach and Point Lookout.

Under the plan, which Kennedy is urging state and federal officials to support, the gates would be built on the west end at the entrance to East Rockaway Inlet at Atlantic Beach and nine miles to the east at Jones inlet at Point Lookout.

The project would forever change the landscape of Long Island, but Army Corps officials are considering it among several options to protect the South Shore.

Kennedy said those gates would protect Reynolds Channel from major flooding as well as South Shore communities, including Freeport, Oceanside, Island Park, Bellmore and Seaford.

“This is absolutely realistic and imperative to all of Long Island,” Kennedy said at the summit. “If you lose Freeport, you’re going to start losing Long Island. Insurance rates will go up and property value will go down. It will be a rippling effect to the economy for the rest of Long Island.”

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The proposal will be included in the Army Corps of Engineers’ back bays feasibility study, which will be paid for with $3.5 million in state, federal and Nassau County funds. Federal funding for the three-year study was secured in September by Sen. Chuck Schumer (D-NY), and it is expected to begin early next year.

The Army Corps study would analyze cost, flood protection and the environmental impact of adding the gates compared to other protective measures, such as raising homes, Army Corps Project Manager Mark Lulka said.

“It is feasible,” Lulka said of the tidal gate idea. “It would have to meet several criteria ... The state of New York, Nassau County and towns would have to be on board with this.”

Kennedy said the proposal was modeled after tidal gates in Stamford, Connecticut, Bedford, Massachusetts, and Rotterdam in the Netherlands, where the gates have stood for decades and have proved effective. The gates only would be closed for a few hours during a major storm or high tide, and otherwise would remain open or stored underwater, Kennedy said.

The Army Corps has not given an estimate to build the gates, but Kennedy said he estimated the cost would total near $300 million. He said the amount of savings in flood damage would be worth the expense.

Freeport sustained about $10 million in damage to municipal buildings after superstorm Sandy hit in 2012 and nearly $10 million in additional infrastructure damage. The storm caused massive flooding in 3,500 homes, Kennedy said. That included 15,000 tons of garbage and oil that was washed away.

Freeport gains more than $15 million in annual sales taxes — revenue that could be lost from damaged businesses after a major storm.

“Businesses rely and survive on being on the water,” Kennedy said. “We can’t stop nature, but we can minimize the damage. The future of Nassau County depends on this being done.”

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A large brunt of Sandy’s damage came from flooding in the bay, as residual storm surge from the Atlantic.

The gates also would protect Long Beach’s bayfront, where city officials are planning a state-funded pair of projects to add more than $33 million in bulkheads to the city’s north shore and infrastructure.

“We were proud to stand with Freeport Mayor Kennedy when he proposed an innovative concept to protect the South Shore, and continue to support studying the feasibility,” Long Beach City Manager Jack Schnirman said.