>I was thinking about how a watermill could be implemented which lead to the waterfall idea. But both functional and decorative versions could be made.

mh. I like the idea of a watermill. But instead of adapting to a river, which is hard to make in OC, it should adapt to a waterfall, as you may have metioned. That sounds pretty creative and sweet for me. On the other hand, waterfalls may be very static and have to be placed by a mapdesigner. A good solution would be, that the player could collect water on a great surface and lead it into a hole in the ground where the waterfallmill would be. Just  a way to get rid of that would be necessary. Show some solidarity to renewable energies!