I agree that comparing low head dams to dam failures is a weird comparison, so here’s a different one - on average about 10% of fatalities on moving water (ie r

I agree that comparing low head dams to dam failures is a weird comparison, so here’s a different one - on average about 10% of fatalities on moving water (ie rivers) are caused by low head dams (source: American Whitewater). That’s a lot. As you note, hydraulic jumps occur naturally (and that’s what makes whitewater kayaking fun!), and deaths do occur on natural holes as well. Naturally occuring recirculating holes, however, are not as deadly as low head dams because they are rarely as uniform or as wide. There’s usually something that breaks up the flow or a place from which rescuers can reach the victim with a rope. Dams are typically wide and smoothly uniform across the width of the river leaving no place to escape. Whitewater boaters (the people most likely to come across natual hydraulics) learn early how to distinguish the fun hydraulics from the scary ones. It’s usually inexperienced boaters that see the small drop of a low head dam and think it looks like a fun ride.