I'm attempting to replace water with a custom block based on its biome. But seem to be having an issue figuring out the proper way to handle this in 1.14.  I believe earlier versions had an event for population. But am unclear of a way in 1.14 I never messed with world gen in the earlier versions, but looks like its changed in 1.14 from what I can tell. Any help to some reading material or examples would be great.