How to prevent all caves from flooding below y60 in custom dimension?

In my custom dimension, it seems the universal y60 fluid level applies to caves, which is not ideal because this means all caves, and I mean EVERY cave, is flooded entirely below y60. You can see why this would be inconvenient!

Is there any way to prevent this from happening without disabling fluid spawns in the dimension? I like having rivers and such but don't want all my caves to be submerged entirely (especially because this produces some bugs when interacting with the universal lava floor at the bottom of the world.)

Also, side note, it seems custom dimension generation is independent of the world seed, causing the same terrain and biomes every world, but thats a different issue.