I'm guessing you were going more for the control of the water and reflection than composition in the first 6 shots? In my opnion I don't really think the first two are over exposed - to me its just the harsh sun on the spillway itself that is very distracting, however I think if you'd exposed for it, the rest of the shot would have been underexposed. It would have been better to wait for the sun to shift or to have used a polarizering filter to cut the glare.
On shots 3 &4 ---3 seems to be out of focus [at least on my monitor] and 4 is overexposed though it is a nice capture of stopping the water - just not very interesting. But again I'm going to assume you were practicing stopping the action rather than composition.
#4 & #6 - one seems under exposed the other over exposed and since that appears to be a metal sculpture I would have chosen to use a polarizer to cut the glare on the sculpture and bring out the reflection more and it would have helped to darken the sky as well. Looks like you might have been shooting in the middle of the day?