The problem is not the tech that is in the hydro-generators but the dams, themselves, silt up. They hold a lot less water and thus, less energy to drive hydro-g

The problem is not the tech that is in the hydro-generators but the dams, themselves, silt up. They hold a lot less water and thus, less energy to drive hydro-generators. To restore a silted up dam, you would have to clean it out, which is a whole nother environmental issue in itself.