Lindsay Rimer, 13, from Hebden Bridge, disappeared on 7 November 1994.
Two canal workers found her body, weighted down with a stone, in the Rochdale canal five months later. Her killer has never been identified.
Andy Glover, from Mytholmroyd, was checking for debris when he spotted something in the water.
He said: "We thought that it was a sheep.
"As we pulled it towards us, the body rolled in the water. There was no mistaking who it was, we saw the strands of hair on her face and knew we had found Lindsay Rimer."
Ms Rimer left her home in Cambridge Street at about 22:00 GMT and met her mother at the Trades Club in Hebden Bridge.
The last-known sighting of her was caught on CCTV 20 minutes later as she bought cornflakes on Crown Street.
Her body was recovered a mile upstream from the town centre in April 1995.
"I got home late that day, and my wife was asking where I had been and why I hadn't phoned," Mr Glover said.
"I just said, 'We have found her.'
"I didn't need to say who, she knew instantly I was talking about Lindsay."
"It has stayed with me, it always will," he added.
In April, West Yorkshire Police said a new DNA profile had been identified which it hoped would lead them to identify the killer.
Det Supt Simon Atkinson, from West Yorkshire Police, said: "We are still waiting for that one 'golden nugget' that leads us to Lindsay's killer and hope that the person who knows what happened will come forward to help us solve the case, and bring closure to the Rimer family."
A man who found the body of a murdered teenager in a West Yorkshire canal 22 years ago has spoken about the harrowing discovery for the first time.