Mr Crerar will recommend to the Central Otago District and the Otago Regional councils that warning signs outlining the dangers of swimming in the area be erected after the death of Darrell Lee Joseph Walker while swimming on November 11, 2008.
His body has never been found, despite a five-day search, which started minutes after he was swept away, and a second search of the river two weeks later.
Mr Crerar indicated at an inquest hearing in Dunedin this week that, on the balance of probabilities and the other evidence available, his final finding was that Darrell drowned when he was swept away after he got into difficulty because of the swift flow and undertow of the river.
He said the evidence of Darrell's friend, Michael Chilcott, who was swimming with Darrell, was particularly compelling.
Mr Chilcott (now 18) told the court he and his friend were hot so decided to go for a swim.
They had chosen a spot about 2km south of the Roxburgh dam where the water "looked calm", but when they entered the water it was much swifter and colder than they had anticipated.
Both youths got into trouble, but Mr Chilcott managed to grab the branch of a tree and pull himself to safety.
He saw his friend experience difficulty in the water and saw his head go under.
"I did not see him again from then on."
Mr Crerar said it appeared the teens had not sufficiently understood how hazardous the Clutha River was.
"The river is significantly more dangerous than it appears."
He intended to forward a copy of his finding to the Central Otago District Council and the Otago Regional Council, including a recommendation that warning signs outlining the dangers of swimming in the area be installed at the end of tracks down to the river.
Other publicity about the dangers should also be distributed in the region, he said.
