Emergency rescue teams were scrambled to reports of a man in the River Lune, says the Coastguard.
Police officers, fire crews, a boat team from Preston fire station and an RNLI lifeboat were all called out to the incident near the Millennium Bridge at around 5.30am on Wednesday April 14.
The man was led to safety by police officers and taken to hospital for assessment.
A spokesman for the Coastguard said: "Our RNLI volunteer lifeboat crew to assist police officers dealing with an incident involving a man, described as ‘in low mood’, near the Millennium Bridge in Lancaster.
"The lifeboat crew were en-route to the scene with their inshore rescue hovercraft when HM Coastguard cancelled the launch, after it was reported that the
man was no longer in danger and safely in police custody."
The man is not believed to have been injured in the incident.