I've spent a good bit of time through the years on vacation or working in Colorado. The Big Thompson canyon flood is something that probably got me interested in weather and floods. I was in the canyon only a few weeks prior to the '76 flood. I've been back numerous times. When you talk about flash floods nothing tops Big Thompson as far as I know. There are actually signs in the canyon that say if you hear the flood sirens go off stop your vehicle and start climbing...…
Point being you don't have to be at sea level or next to a major river to have devastating flood events.
https://en.wikipedia.org/wiki/Big_Thompson_River