Interesting subject it's true. The justification for damming of rivers for various reasons is often debatable.
Everything has a price as the Egyptians are learning. Since the Aswan dam was installed on the Nile the renewal of the bottom land farmed by the locals has ceased to occur. Used to be the Nile dumped myriad tons of silt from the high country onto the flood plain of the Nile. The agricultural treasure that resulted supported the Pharoahs and the Egyptian Civilization for millenia. Aswan ended the annual replenishment of the agricultural treasure.
Weren't the bad floods along the Missouri River a few years ago the result of the Corp attempting to justify their existence with bad science? I don't know, just asking. I know there was a lot of fingerpointing going on about trying to force a river to do what it and gravity said wasn't possible.