I've got another question.

This one is regarding my anomaly of a river:

Is it possible for a river to be fed by a large spring that is in turn fed by an underground river?

My thought was to have a sea or a whole ocean underneath the mountains, as another unwanted effect of the spell, and the underground river would be fed from this body of water. This, of course, begs the question of whether an underground lake/sea/ocean is possible...
Heh, super-duper-wild evocation...