BUR #3189 has been approved by @evazion.
create implication shallow_water -> water
Can't have shallow water without there being water, I looked and there has been no previous topic about this either.
I'm not sure how deep we want to restrict shallow water to so I just threw together a quick wiki for it.
EDIT: The bulk update request #3189 (forum #170662) has been approved by @evazion.
Updated by DanbooruBot