Seems about a stop or two over exposed, which would be why the colours aren't really popping in this image. At first I wondered what kind of film you were using, but with Velvia, even 100 ISO, you should be getting more vivid colours.
Perhaps try bracketing a bit more... take one shot metering off the foliage, one off the brightest thing in the image (the water) and one off something in the middle. At least one of the three will be the right exposure. Slide film can be a bit tempermental with such a range of contrasts... you'll either have blown out highlights or really dark shadows... you just have to choose the lesser of the two evils sometimes.
I like how the trees add a natural-like frame to the top of the image. I'm not sure if you used a ND filter, but that would also help you get the "soft water" look by making the scene darker so a longer exposure would be needed. I also tried playing with 2 polarising filters when I didn't have the ND... you can put both on at the same time and turn them until the scene is almost dark. Even in sunshine you can get long exposure shots this way. Wow... this is the longest critique I might have ever written! *grin* Thanks so much for your input on my stuff... it's always appreciated.
You got a great composition but find the two tree at the top corners, looks out of place. Also your lighting seem to be excellent especially with the use of a fill flash. I fixed it to show you what I mean. I darken the background a little bit and played with the constrast. Hope you like it.