As pictured below, Sildur's Enhanced Default shader disables underwater fog, making it look as though I'm not underwater at all (save for the surface of the water above me) and increasing visibility. I would like to re-enable underwater fog, so it looks the same as or similar to how it does without any shaders on. The shader provides no options for this, so the code of the shader would need to be changed. This is where I'm experiencing difficulties, as I have no familiarity with how shaders are programmed and can't identify exactly what's altering the underwater fog.
What changes would need to be made in order to stop the shader from disabling underwater fog?