both should be caused by https://wowdev.wiki/ADT/v18#MCNK_chunk pointing to bad MCLQ and MCCV chunks, while the water seems fine in tiles nearby so that's weird.
I suggest you using mh2o utilities by Mjollna to copy the original water and restore it as it was after the editing of the map. The issue is quite interesting though. I have never seen it before.