Moving water is always a huge challenge. It's always changing and it has reflections from the land and bouncy mirror-like parts on the white water. To me it helps to divide it into warm and cool: what is in shadow and what is in sun?
The rocks are a perfect resting point from the greens. The oranges and violets make it sing better.
BTW Three of my most talented young students had their first show at my studio yesterday. They have been working for 3 years and their dedication is obvious in their work quality. For this show they not only created the work but they learned how to frame it and wrote their first artist's statement.