I was trying to combine city spheres with an atlantis world, and I get this:

Water in chunks around city blocks are lowered by 1, and become normal further outside.

Water level is also lowered on highway + 1 chunk beyond.

I've tried to adjust various parameters to see if they have effect, but without success.
Is there some sort of "special zone" around cities that can make this happen?
To replicate, simply use atlantis as outsideProfile for biosphere profile. Same happens if I add some water level to bio_wasteland child profile.