Similar to MC-193885, tree growth (Azalea, Acacia, Jungle, Oak, Spruce, Dark Oak, 4 x 4 Jungle, 4 x 4 Spruce) replaces water.
Unlike MC-193885, this doesn't replace lava.

It does not replace water logged blocks.

Demonstration:
https://gfycat.com/mistyconsiderateavians
(The Stripped Crimson Stem is to prevent the sapling from being washed away. Command blocks were for testing)

Pretty much duplicates MC-193885. I'll merge the details of this one to that.