Many dams have high environmental costs that outweigh their value. Removing them is the only sensible answer. And taking them down can often make economic sense as well.
I hate dams. They wreck the land by interrupting the flood cycle and wreck the river by creating an impassible barrier. Fuck flood control, we just need to build in areas that are safe, and treat flood-prone areas as the natural gift that they are. Way too many river valleys have been destroyed in the name of false security and costly electricity.
Let us not forget one of the great crimes of modern history.
New Orleans should never have existed, really, although that's not a dam issue (more a levee issue, and I don't know how the levees have affected the environment). But they are stupidly flood-prone. EDIT: There is a heightened flood risk in western Minnesota, too. I don't know why.
I had no idea so few dams generated power. Here in the PNW, most of the dams you hear about exist mainly for power generation. In terms of energy production, it is of course a trade-off. The utility companies here are proud of the fact that our energy is "green" because most of it is hydroelectric, ignoring the widespread environmental effects of building those dams. Of course, most of the rest of the country still relies on some form of fossil fuel for its power, and that too has huge environmental costs. Until we have widespread energy generation that is non-emitting, should we not keep hydroelectric dams?
Oh, but don't you see, we're too busy killing brown people to give a shit about our environment.