Origin of the toponym Castalia?

"When the place for the new city was, through such an amazing method, determined, Cadmus decided to sacrifice the cow to the goddess Athena, and with that purpose in mind he sent some of his men to draw water from the spring later called Dirce (some have said Castalia), belonging to Ares, which happened to be guarded by a dragon said to be the offspring of the god or sacred to him."