1. They control the dam and can just open the flood gates to release water.
2. That would imply Russians retreating which they’re not. In fact, all the attacks Ukraine attempted doing over the past three days failed miserably.

Seem that Ukraine has the motivation to blame their failed offensive on the flooding here when explaining themselves to their western masters.

edit: I guess Russia is also forcing Ukraine to flood Kherson from DneproGES that Ukraine controls? https://twitter.com/sinnaig/status/1666494567388962818