I like this photograph. However, I'll tell you what the others are always telling me. There's too much negative space in the foreground. Some of the sky should be cropped. I think the sky is very nice with somber blues, but there's too much of it for this photograph.
Interesting sky colors and I like the seemingly rigid sweep of the clouds. The far end of the lake shows the horizon is not level, which has been mentioned. It's a not uncommon shortcoming of otherwise fine landscape photos and definitely worth the adjustment.
The others have all made very good suggestions. One thing to remember is the Rule of Thirds in photography, your sky takes up too much space, and the black at the bottom takes up too much space. By reworking your camera angle, you could retake this scene and make it much more powerful. :) Have a great day!