The water is a combination of masked local cloud and tiny fake rocks.
I figured a waterfall appears mostly as broken water particles so the cloud is already a particle system and if I made the fake rocks small they
would be a sort of particle system.
I first attempted to apply a water shader to the tiny fake rocks but that approach was super prohibitive on
render time, so for speed the fake rocks have a simple reflective shader.
After I knew where the cliff rock formations would be, I made one waterfall like mask image in camera projection to
define the placement/density of both cloud and fake rocks.