Foyle Search and Rescue came to the aid of a person who had entered the river on Saturday afternoon.
FSR's report reads: "At 17;22hrs Saturday 27/04/19 the Police Service of Northern Ireland activated Foyle Search & Rescue's Pager system to reports by a member of the public that a person had been observed entering the river.
Emergency Response Teams responded to the scene with shore crew activating throw lines to the person in the water with support from a Jet ski.
The boat crew rescued the person and brought them to FSR's Prehen Base.
On arrival they were assessed with spinal precautions applied, and also treated for early onset hypothermia. They were then transferred to the care of NIAS paramedics before being transported to hospital by ambulance.
Thanks to the member of the public, CCTV, PSNI, NIAS & NIFRS and appreciation to our ERT for their quick response and professionalism."