If I try to set a custom water black in any of my biomes to make the oceans/rivers a different block it I get funny crashes when it tries to generate the biome (it says something about dungeon generation in the error, but even removing dungeons doesn't cause it to generate properly).

On a related note, some chunks don't appear to have block replacement working so even when I replace water and still water with the appropriate liquid blocks there are sometimes messed up chunks still.

Closing, as there was never any activity on this issue.