Passage 9.24.1
ἐξ Ἀκραιφνίου δὲ ἰόντι εὐθεῖαν ἐπὶ λίμνην τὴν Κηφισίδα---οἱ δὲ Κωπαΐδα ὀνομάζουσι τὴν αὐτήν--- πεδίον καλούμενόν ἐστιν Ἀθαμάντιον· οἰκῆσαι δὲ Ἀθάμαντα ἐν αὐτῷ φασιν. ἐς δὲ τὴν λίμνην ὅ τε ποταμὸς ὁ Κηφισὸς ἐκδίδωσιν ἀρχόμενος ἐκ Λιλαίας τῆς Φωκέων καὶ διαπλεύσαντί εἰσι Κῶπαι. κεῖνται δὲ αἱ Κῶπαι πόλισμα ἐπὶ τῇ λίμνῃ, τούτου δὲ καὶ Ὅμηρος ἐποιήσατο ἐν καταλόγῳ μνήμην· ἐνταῦθα Δήμητρος καὶ Διονύσου καὶ Σαράπιδός ἐστιν ἱερά.
Going straight from Akraiphnium to the lake called Kephisian—also called Kopais by some—there is a plain known as Athamantion. They say Athamas himself once dwelt in it. Into the lake flows the river Kephisos, whose source is at Lilaia among the Phokians, and sailing across the lake, one arrives at Kopai. Kopai is a small city situated on the shore of the lake, and Homer has also mentioned it in his catalogue. Here there are sanctuaries of Demeter, Dionysos, and Sarapis.