I bought some Woodland Scenics Waterfall effects to make a display base for a Celtos figure a while ago. Got it from Hobbycraft in the model railway section. I think it is different from Water effects.
It is really easy to use. I was happpy with it at the time, but now plan to redo it. That is no fault of the the Water Effects, more a reflection of my skills as a hobbyist. I can try and post a pic if you are interested.
EDIT When I used the Waterfall Effects, I did not need to use a Fishing Line. Simply squirt it out the tube ( its a bit like toothpaste) on to some greaseproof paper in thin lines. Once it is dry peel it off and place as your waterfall, and you attach it to the base/model by applying a bit more from the tube.