I think you'd have to put a flattened cube in the scene for the surface of the water.  Give that cube a microdisplacement texture either using noise or a t-map.  Use refraction in the shader so you can get cool refracted views of whatever is over the water's surface.  If you have caustics on, you should also get some cool light streams if you place a volumetric cloud under the water's surface.  The light cone might work, too, with the newer feature of cones shooting through transparency.

I'm on a deadline or I'd give it a try....

HTH - Dex