The shadows are too much. They seem to really weight the image down. I also wish it would've shown the whole dam. It looks so impressive. I'm not sure how much of it would fit in the frame either because of where you can and can't take pictures there.
Composition is good, background is very nice, there really is almost too much going on to try to grab your attention, but i think what is saving it is the splash of sun on the dam wall keeps drwing me back to the dam, which is the main focus of the shot and for that I commend you