A woman crashed her car through a wooden barrier and sand berm at a U-turn on the Robert Moses Causeway — nearly plunging into the Great South Bay — and was arrested on a charge of driving while intoxicated under Leandra’s Law, authorities said.

“When we got there, the car was flipped on its passenger side on the rocks, just about six inches away from falling into the bay,” West Islip Fire Chief Robert Bilella said Saturday.

The West Islip Fire Department received a call at 8:43 p.m. Friday reporting a car accident at the westbound lanes of the roadway that line the inlet at Robert Moses State Park near Field 2, Bilella said.

State Park Police also responded to the accident at the entrance to Democratic Point and “observed a vehicle at the water’s edge with the occupants trapped inside,” according to a statement issued by the park police.

The driver, Raquel Warburton, 40, of West Babylon, was charged with the felony Leandra’s Law violation and endangering the welfare of a child, park police said. She and her son, who appeared younger than 10, were rescued from the vehicle by firefighters using high-water rescue equipment, Bilella said.

Warburton and her son, who were wearing seat belts, did not appear to be injured but were taken by ambulance to Good Samaritan Hospital Medical Center in West Islip for evaluation, Bilella said.

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Warburton pleaded not guilty at her arraignment Saturday afternoon at First District Court in Central Islip.Her attorney could not be immediately reached.

Bilella said it took about 30 minutes for firefighters to get the family out of the car. Fire departments from Bay Shore, West Babylon and Babylon were called in to assist.

“It happens at least one or two times a year that people just don’t realize they need to turn there and they crash,” Bilella said.

With Khristopher J. Brooks