According to a local Patraean myth, the river Selemnus was originally a mortal man, a young and handsome shepherd who used to feed his flock by the Argyra spring near the town of Argyra. The sea-nymph of that spring, Argyra, fell in love with him and would often visit him and sleep by his side. But as the years passed and Selemnus grew older and less handsome, Argyra ceased to visit him with the same frequency as before. Eventually she stopped coming to him altogether and withdrew to her liquid home.
Selemnus was heartbroken over her desertation. In his despair he wasted away and eventually died of grief. Aphrodite, the goddess of love, pitied the unfortunate man so she turned him into a river which took his name, Selemnos. But even in his new aquatic form he still pined for Argyra and missed her terribly, so Aphrodite further helped him out by wiping out all of his memories of Argyra and his love for her.
For that reason, men and women of Achaea would wash themselves in the waters of the Selemnus in order to rid themselves of their erotic passions. Pausanias, who rarely makes remarks on the legends he relates, comments that if true, this would make the river more valuable to mankind than any wealth.
