I have lived next to the LA River for years. Atwater Village is a storm plain ...people used to have cases in their garages.
Even now, in a heavy rain, people drown....it is deep, fast and powerful.
Biggest problem is it’s pretty mellow so much of the time that people get a dangerous sense of complacency about it, like it’s been thoroughly tamed.
Sure comes alive when it rains, though, and shockingly quickly, which is how people get caught off guard and swept away. Plus those islands just make it seem so hospitable.
“Hey, let’s play ‘Huck Finn’ and go camping out there.”
No bueno!