Well the way it's done, and it will vary depending on the scene (by which I mean if the sky is in the shot or not) With sky not in the shot or how much sunight is on the water, you can take a single long exposure, heighten your aperture but not too much, generally lenses start to lose sharpness past f8. If the sun light is concealed by clouds or the trees above you'll get a longer exposer, half a second is long enough to get the water looking milky but the longer you take the exposure the creamier it gets. You can use a Neutral Density Filter though, which will reduce the amount of light that gets through to the sensor allowing you (forcing you to, rather) to lengthen exposure and get the creamy water look. Without the filter and with the sky in the shot, a good way to do this is take 2 shots, one long exposure up to about a second, and one standard exposure, and use photoshop layer masks to (or stack them on top of each other and use the eraser if you don't know how to use mask layers) and reveal the sky, as it will be over exposed. It's really a lot easier to just buy a ND filter to be honest, a good quality one would be preferable, like a Hoya Pro-d or something like that, of if you have the cash a B+W. Anything above 3stops light reduction will get you the effect you want but you can exposure for a longer period the darker the ND filter, you can get 10stop filters that let you long expose broad daylight up to 30 seconds, which are cool for twilight coastal shots or shots of small piers, you get that glowey haze (which is actually traces of waves through out the exposure) around the cliffs/pier and stuff like that.
Without filters is a lot trickier, which is why I like doing it, but with will give you a guaranteed positive result without potentially heavy post editing.
Well I take a normal exposure which freezes the trees, stops them from blurring through the lengthened exposure for the ware flowing. Then align the layers and erase the moving ferns and blend the layers, works nicely
Incredible capture! I absolutely love all the details and how the water is so silky and smooth. The whitish-blue hue contrasts really well with the surrounding greenery as well. Absolutely gorgeous work!