Also, traditionally you install solar panels on steel pillars set in concrete in the ground, but theres no electrical reason you can't mount them on top of the

Also, traditionally you install solar panels on steel pillars set in concrete in the ground, but theres no electrical reason you can't mount them on top of the hydro lake, on floats. There are engineering concerns with waves and the usual problems anytime you mix water electricity and metal. There are biological concerns where polluted water is already anoxic enough so blocking light is not going to help. Still there's no inherent reason the land can only be applied to one tech. Maybe if you have an infinite supply of cheap incredibly tall concrete pylons you could mount windmills too, although that's sounding unlikely.