Yes, if you use a test color and the end of the line, and a color adjust from the lake SSS, you can easily see the width of the edge changing if you change parameters of the SSS. You can also use 2 color adjusts and multiply (or multiply complement) to make a ring mask around your water, perhaps for some coastal high reeds or so, or foam...
I would also reduce choppiness, and work on your shrub distribution; more patchy.
Oh, and post jpg's instead of png's. Jpg's load faster and take less space.