Borders between different water levels don't generate below the water.

The borders between different water levels in the new aquifer caves don't generate below the water.

What I expected to happen was...:
What I believe should have happened would be that the borders between two water levels would go under the water, with areas of it connecting down to the floor below. There would probably also be openings to go through the border.

What actually happened was...:
Instead, the borders between the two water levels do not generate below the water line leaving the border looking very unnatural, and sometimes only one block thin.

Steps to Reproduce:
1. Find an area with two different water levels

2. Look at the borders between them and notice how unnatural they look