Passage 10.8.9
ἐκ δὲ τοῦ γυμνασίου τὴν ἐς τὸ ἱερὸν ἀνιόντι ἔστιν ἐν δεξιᾷ τῆς ὁδοῦ τὸ ὕδωρ τῆς Κασταλίας, καὶ πιεῖν ἡδὺ καὶ λοῦσθαι καλόν. δοῦναι δὲ τὸ ὄνομα τῇ πηγῇ γυναῖκα λέγουσιν ἐπιχωρίαν, οἱ δὲ ἄνδρα Καστάλιον· Πανύασσις δὲ ὁ Πολυάρχου πεποιηκὼς ἐς Ἡρακλέα ἔπη θυγατέρα Ἀχελῴου τὴν Κασταλίαν φησὶν εἶναι. λέγει γὰρ δὴ περὶ τοῦ Ἡρακλέους· Παρνησσὸν νιφόεντα θοοῖς διὰ ποσσὶ περήσας ἵκετο Κασταλίης Ἀχελωΐδος ἄμβροτον ὕδωρ. Panyassis, work unknown
Going up from the gymnasium towards the sanctuary, on the right side of the road is the water of Castalia, pleasant to drink and beautiful for bathing. They say the spring was named from a local woman, though others say it was named after a man, Castalius. Panyassis son of Polyarchus, however, who composed verses about Heracles, claims that Castalia was a daughter of Acheloüs. For he says thus concerning Heracles: "Having swiftly crossed snowy Parnassus with swift feet, He reached the immortal water of Castalia, daughter of Acheloüs."