I've seen enough of Ted Robinson's "Aquatic Presentations" (his term), but for sheer length, this thread would not be complete without the 18th at Shadow Creek or the two at Trump National in Rancho Palos Verdes.
I think - as a matter of technicality - the longest artificial golf course waterfall is Cascata in Boulder City, NV. . . . . .
The winner in the category of "Waterfall that most resembles a prop at Disneyland" goes to #17 at the aforementioned Shadow Creek . . . . .
All it needs is a mermaid or two and I would jump in myself.