remember that the sky in this model is set to white and no sun/shadows - so to see how the water will 'truly' look in your scene, you need to set it up in your scene.
white = "clear" water.
.. if you don't unlink the color first
but just change it, it will change in the SketchUp water material... but if you unlink
the color before you change it, you can render it with any look you want in Twilight, but "leave the SketchUp looking water" the same as it appears in SketchUp.
If you unlink, then change the color to brown, or another textur
e, you will get a different "look" but you will need to render it to see the difference because the SU texture is now unlinked
and independant from the color in Twilight.