Drowned Attempting Dog Rescue
In Toronto several weirs aka. drowning machines were put in the Humber and Don rivers.
Dog walkers going in to rescue dogs invariably drowned if they were swept over a weir. In all but one case the dog got itself out.
Low head dams are serious drowning machines. People are trapped in the backwash. About the only way to save yourself is to dive for the bottom to reach the current going downstream.
Paddlers are about the only people besides trained water rescuers who understand the danger.