High Bridge police responded to a wooded area near the Lake Solitude waterfall off the Columbia Trail behind houses on Mountain Avenue just after 12:30 p.m., authorities said.
The teen -- who was not injured but couldn't move -- was on a branch of a tree sticking out of the side of a cliff approximately 50 or 60 feet above the water at the base of the dam, Hunterdon County Technical Rescue Task Force said in a Facebook post.
Firefighter and EMT James Regan rappelled off the cliff in full harness gear by attaching ropes above the boy, and others anchored to a tree creating a high-angle rope rescue.
Once he reached the boy, Regan adjusted the teen's harness and moved him under the branch before rappelling down together to the water.
The boy was helped into a Clinton Rescue Squad boat and moved across the water to the other shoreline for easier access before being turned over to his parents.
Responders included High Bridge fire and EMS, Hunterdon Medical Center MICU EMS-2.
Participating Hunterdon County Technical Rescue Task Force agencies included Lambertville FD, Whitehouse Rescue, Clinton Rescue, Flemington - Raritan Rescue, MD1 Program EMS Physicians, and Hunterdon County Office of Emergency Management.
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