What you have there on it's own merits is photo real. What's missing is the blending, and by that I mean, what happens when the snow level reaches the water? Is there ice? Does anything else grow there? Grass etc, and where.
Should the trees also have a little snow on them?
Love the rock texture, and actually the sparseness of the sky. I wouldn't touch those at all, except maybe add a little reflectivity around the lake edge.