Is there more noise than need-be in the sky and the lake reflections?
Were you afloat, or without a way to make the camera stable - so you chose 1/100s ISO250 instead of a longer exposure?
Is it that you work with JPG rather than RAW - so you don't try to ETTR and then correct the exposure with post-processing?
I'm just trying to understand what you chose to do. Over the past few months I've seen that RAW and ETTR are better in low-light, even with my entry-level camera, so I guess there are reasons you didn't try that approach.