Hey there @Real! Welcome to the community! Generally the water plugin was not originally meant to be procedural. It’s meant to be locked in by compile time just like landscapes (especially due to the landscape integration). However, you may be able to dig into the source for the water plugin to see where it updates the location data for both the landscape brushes and water visuals.
Alternatively, some changes that let you adjust the water body visually (but without the physics or post process material) were being discussed here: