In the mod that I'm making, I don't want any above-ground water. So, I went through the painful process of making new subclasses of every class that generates water and replaced it all. (I didn't replace it all at once. It was only after I went through several times replacing what I thought was causing the water that I eventually replaced all of them finally the above-ground water is gone.) However, I still want those single underground water source blocks. I don't want underground lakes, just those singular source blocks you find in caves. (Also, I don't mind if they generate on the surface making waterfalls. I just don't want bodies of water on the surface.) I was wondering if anyone knew where in the source code these underground water blocks are? I've looked and looked, changing some of them back to water, but to no avail. If anyone knows where these are located, it would be greatly appreciated.

You could just make your own by adding worldgen code that picks random spots during worldgen and puts a water source there if there's an air block on one side and stone/any other block on the others. I think there are quite a few tutorials for doing things like this, and it would seem you already have some experience with worldgen, so it shouldn't be hard

Yeah, after 3 hours of no replies, that's what I ended up doing. Which is a bit unfortunate because now my code iterates through one forth of every chunk during generation, making generation that much slower..  Ah well, it works the way I want it to, and I have more control over it this way.