Crews responded to the dam on reports of a man with a head laceration around 3:50 p.m. and found a man in his 30s who had walked out from the dam and up to the canal path, Lambertville City Police Lt. Robert Brown said.
A follow-up investigation found that the man, from Doylestown, PA, had dove headfirst into the river, struck a large rock, and suffered a deep laceration to his head.
Crews requested a NorthSTAR medical helicopter, which landed at Ely Field, before taking him to Capital Health Trauma Center in Trenton for further treatment.
Other assisting agencies include the Lambertville-New Hope Rescue Squad, Lambertville Fire Department, and HMC Paramedics.
Click here to follow Daily Voice North Hunterdon and receive free news updates.