The Krathis (or Crathis) river was named for a goatherd and was used by Kroton to destroy Sybaris.
Aelian, On Animals 6. 42 (trans. Scholfield):
"An Italian story, which records an event that occurred when affairs were at their prime in the city of Sybaris, has reached me and is worth relating. A mere boy, a goatherd by occupation, whose name was Krathis, under an erotic impulse lay with the prettiest of his goats, and took pleasure in the union, and whenever he wanted sexual pleasure he would go to her; and he kept her as his darling. Moreover the amorous goatherd would bring to his loved one aforesaid such gifts as he could procure, offering her sometimes the loveliest twigs of tree-medick, and often bindweed and mastic to eat, so making her mouth fragrant for him if he should want to kiss her. And he even prepared for her, as for a bride, a leafy bed ever so luxurious and soft to sleep in. But the he-goat, the leader of the flock, did not observe these proceedings with indifference, but was filled with jealousy. For a time however he dissembled his anger and watched for the boy to be seated and asleep; and there he was, his face dropped forward on his chest. So with all the force at his command the he-goat dashed his head against him and smashed the fore-part of his skull. The event reached the ears of the inhabitants, and it was no mean tomb that they erected for the boy; and they called their river 'the Krathis ' after him. From his union with the she-goat a baby was born with the legs of a goat and the face of a man. The story goes that he was deified and was worshipped as a god [a Pan] of the woods and vales."
In 510 B.C., Telys took power as king of Sybaris exiling and confiscating the estates of five hundred of the wealthiest citizens, who took refuge in Krotona. Telys sent ambassadors threatening war unless Kroton gave up the exiles, which would have meant certain death for them. According to Diodorus of Sicily, Pythagoras persuaded the Krotonians to protect the suppliants, whom they had granted political asylum. In the ensuing war Kroton defeated the far larger Sybarite forces. Kroton then destroyed the city of Sybaris by turning the course of the river Krathis, so that it inundated the site of the city and buried the ruins under the deposits that it brought down. (Diod. xii. 9, 10; Strabo vi. p. 263; Herod. v. 44; Athenae. xii. p. 521; Scymn. Ch. 337-360.) This catastrophe seems to have been viewed by many of the Greeks as a divine vengeance upon the Sybarites for their pride and arrogance, caused by their excessive prosperity, more especially for the contempt they had shown for the great festival of the Olympic Games, which they are said to have attempted to supplant by attracting the principal artists, athletes, etc., to their own public games. (Scymn. Ch. 350-360; Athen. l. c.) It is certain that Sybaris was never restored. The surviving inhabitants took refuge at Laüs and Scidrus, on the shores of the Tyrrhenian sea. An attempt was indeed made, 58 years after the destruction of the city, to establish them anew on the ancient site, but they were quickly driven out by the Crotoniats, and the fugitives afterwards combined with the Athenian colonists in the foundation of Thurii. At the present day the site is utterly desolate, and even the exact position of the ancient city cannot be determined.
Sources: http://en.wikipedia.org/wiki/Sybaris