Passage 5.7.1
ἀφικομένῳ δὲ ἐς Ὀλυμπίαν ἐνταῦθα ἤδη τὸ ὕδωρ ἐστὶ τοῦ Ἀλφειοῦ πλήθει τε πολὺ ἰδόντι καὶ ἥδιστον, ἅτε ποταμῶν καὶ ἄλλων καὶ λόγου μάλιστα ἀξίων ἑπτὰ ἐς αὐτὸν ῥεόντων. διὰ Μεγάλης μέν γε πόλεως Ἑλισσὼν ἐρχόμενος ἐκδίδωσιν ἐς τὸν Ἀλφειόν, Βρενθεάτης δὲ ἐκ τῆς Μεγαλοπολιτῶν γῆς, παρὰ δὲ Γόρτυναν ἔνθα ἱερὸν Ἀσκληπιοῦ, παρὰ δὴ ταῦτα Γορτύνιος ῥέων, ἐκ δὲ Μελαινεῶν Βουφάγος τῆς Μεγαλοπολίτιδος μεταξὺ καὶ Ἡραιίτιδος χώρας, ἐκ δὲ τῆς Κλειτορίων Λάδων, ἐκ δὲ Ἐρυμάνθου τοῦ ὄρους ὁμώνυμος τῷ ὄρει. οὗτοι μὲν ἐξ Ἀρκαδίας κατίασιν ἐς τὸν Ἀλφειόν, Κλάδεος δὲ ἐρχόμενος ἐκ τῆς Ἠλείας συμμίσγει οἱ τὸ ῥεῦμα· αὐτῷ δὲ ἐν τῇ Ἀρκάδων τῷ Ἀλφειῷ καὶ οὐχὶ ἐκ τῆς Ἠλείας εἰσὶν αἱ πηγαί.
Upon arriving at Olympia, you find here that the water of the Alpheios is already abundant and very pleasant to look upon, being especially sweet because seven rivers flow into it, rivers remarkable among others and particularly worthy of mention. The Helisson flows through Megalopolis and empties into the Alpheios; the Brentheates comes from the territory of the Megalopolitans; the Gortynios river passes near Gortys, where the sanctuary of Asclepius is; the Bouphagos river rises from Melaineai, located between the Megalopolitan and Heraean lands; the Ladon flows from the district of Kleitor; and the Erymanthus, flowing from the mountain of the same name. All these rivers descend from Arcadia into the Alpheios, while the Cladeus, flowing from Elis, mingles its stream with it. The sources of the Alpheios itself are in Arcadian territory, not in Elis.