Passage 2.15.5
λέγεται δὲ καὶ ὧδε λόγος· Φορωνέα ἐν τῇ γῇ ταύτῃ γενέσθαι πρῶτον, Ἴναχον δὲ οὐκ ἄνδρα ἀλλὰ τὸν ποταμὸν πατέρα εἶναι Φορωνεῖ· τοῦτον δὲ Ποσειδῶνι καὶ Ἥρᾳ δικάσαι περὶ τῆς χώρας, σὺν δὲ αὐτῷ Κηφισόν τε καὶ Ἀστερίωνα καὶ τὸν Ἴναχον ποταμόν· κρινάντων δὲ Ἥρας εἶναι τὴν γῆν, οὕτω σφίσιν ἀφανίσαι τὸ ὕδωρ Ποσειδῶνα. καὶ διὰ τοῦτο οὔτε Ἴναχος ὕδωρ οὔτε ἄλλος παρέχεται τῶν εἰρημένων ποταμῶν ὅτι μὴ ὕσαντος τοῦ θεοῦ· θέρους δὲ αὖά σφισίν ἐστι τὰ ῥεύματα πλὴν τῶν ἐν Λέρνῃ. Φορωνεὺς δὲ ὁ Ἰνάχου τοὺς ἀνθρώπους συνήγαγε πρῶτον ἐς κοινόν, σποράδας τέως καὶ ἐφʼ ἑαυτῶν ἑκάστοτε οἰκοῦντας· καὶ τὸ χωρίον ἐς ὃ πρῶτον ἠθροίσθησαν ἄστυ ὠνομάσθη Φορωνικόν.
The story is also told thus: that Phoroneus was the first to be born in this land, and that his father, Inachus, was not a man, but rather the river itself. They say that Phoroneus was chosen to arbitrate between Poseidon and Hera concerning the country, with Cephisus, Asterion, and the river Inachus himself as co-judges. When these ruled the land to belong to Hera, Poseidon in anger dried up their waters. For this reason neither Inachus nor any of these rivers provides water unless it rains, and in summer their streams run dry, except those in the district of Lerna. Phoroneus, the son of Inachus, was the first to gather mankind into a community, whereas before this people had lived scattered and separate from one another. The place into which they first assembled was called the city of Phoroneus.