Jaka B,
I think nearly all waterfalls are enhanced with pumps. In most areas of the country, streams go occaisonally dry, often in summer, during the busiest golf season. Most owners would want to be sure their prime time customers see all the course has to offer, and add pumps just to be sure.
Technically, it is actually better to build a waterfall outside a natural water course, as the occaisonal heavy rain can wash out all but the sturdiest subgrade, and natural streams have to be concreted over to hold up, and even lesser flood cause debris cleanup and damage. Better to create a fake stream coming into a fake water fall, if you are going to do it....Don't ask me how I know this.
I don't know if you have been to Opryland in Nashville, but they have many interior waterfalls in the hotel. When we brought up the idea for the course, they mentioned that its not even worth doing if the pump is less than 3000GPM. It takes that much, or more, to create the big splashes at a place like Shadow Creek.
There are very few places, IMHO, where a waterfall is a real addtion to a golf course, but Shadow Creek and all of Palm Springs are so artificial anyway, they would be two good examples where they probably work. Wherever an owner or architect decides they are necessary, then, the techicalities of making them really, really work are probably more involved than almost any golfer would think.
Truth in posting announcement -
I have created waterfalls on Holes 1 and 3 at Colbert Hills (gently enhancing the natural stream bed with 600GPM), Springhouse GC (at 4 green) and am doing two at Fortune Bay in Tower, MN right now, which is why this caught my attention.