I don't have save when exactly this happened, but in my old backup save Gilden had city that used Water Shard as wild improvement.
On the other hand, in my current save, that city doesn't exist anymore (probably destroyed by monsters), and Water Shard is completely gone too.
What's more interesting is that currently there is not a single Water Shard on the map (just checked with cheat mode), making Spell of Making victory impossible.
