The trick are filters that block the amount of light and give you the chance (and since they work like "sunglasses" for your lens also the necessity) to photograph with long exposures even during the day, so you get that foggy-dreamy-floating aspect of running water.
I shall move this thread to the Nature and Landscape Gallery though, since our Critique Forum guidelines say "Only one photo - and please ask for some quite specific critique on that", you see?
And could you go back into your thread with the help of the "Edit" button and put the missing spaces between your first and second photo, please? Else, I could do that for you.