Timothy Mercer, of Greenhill Road, Wakefield, had been reported to police as a high risk missing person on September 26 last year.
The 50-year-old, who was unemployed but formerly worked as a salesman, was last seen alive on September 21 at a pub on Barnsley Road in the city.
Wakefield Coroner’s Court was told nearly four months later, on January 14, an environment agency worker was cutting back trees at Owler Beck close to Pugneys Country Park, and spotted the body of a man in the water.
Emergency services were called at around 10.20am.
A provisional post-mortem report said the cause of Mr Mercer’s death had not yet been established.
Coroner David Hinchliff adjourned the inquest pending the outcome of enquiries.