Here in San Antonio we don’t even try - people fall in the San Antonio River downtown pretty frequently.
I can see that but very different rivers size wise
He likely wanderered down by the river intoxicated from booze and fell in unable to stay afloat or get back up on the bank
If there was foul play it’ll show up at autopsy
Something significant beyond booze will be found on toxicology
Till then it’s intoxicated kid fell into fairly sizable river and drowned
Sad for his folks
His cards may have been in his top pocket etc like mine are and floated to the bank
He could have been assaulted by dope campers
That is a possibility but less likely than the fell into water theory here
It happens here in Nashville and elsewhere