A River Reawakened

That's also romantic. It's more like, when there were much fewer people living on the planet.

Because no serious environmentalist considers big hydro a net positive.

The power stations at those dams didn't produce much power to begin with, them being very old designs. Note that most of the tens of thousands of dams in the US are just old relics serving no function, that are very expensive to remove. I agree that it's not an environmentally friendly way to generate power.