Police and coastguards were called to reports of someone in the water last night in Bridgwater.
Fire crews, the BARB Burnham-on-Sea hovercraft and search and rescue teams all attended just before 930pm.
The person was eventually spotted on CCTV heading back into town - and crews were stood down.
Crews have since praised the person who called 999, say it was a great multi-agency response and could have been a much worse outcome.
A spokesperson for the Burnham Coastguard Rescue Team said: "This evening we were tasked to Bridgwater to liaise with the Avon and Somerset Police as there had been reports of a person entering the water in the river.
"With the flow of the river and the darkness shrouding the view of the water, multiple assets were tasked as the cold water made it a matter of urgency.
"BARB Search & Rescue - Burnham-on-Sea hovercraft were tasked along with their boat, Devon & Somerset Fire & Rescue Service and RNLI Lifeboats at Burnham-on-Sea and the HART (Hazardous Area Rescue Team) team from the Ambulance service were in attendance.
"The teams prepared initially for a water rescue and a search as there was no confirmation of where the person was.
"Police were actively investigating and were in close contact with the CCTV rooms to see what further information they could gather and any location of where the person was last seen.
"Finally, the CCTV had a postive fix on the person and they had been spotted on camera heading back into town, there was no one in the water!
"This was the best news because it meant there was no one in danger or had entered the water, the search plans and water rescue equipment was not needed and we could all return back to our respective bases.
"This goes to show that if there is a chance of saving a life then every asset needed to help ensure that positive outcome is rightly tasked.
"Time is imperative so if you see anyone fall into the water dial 999 immediately, the water temperature is dropping now and it can bring on cold water shock in a matter of seconds.
"A great multi-agency response to what could have been a far worse situation."