The alternative name "Oi-gawa River"(大堰川) for the Katsura-gawa River originated from the weirs (堰) for agriculture built by the Hata clan who were immigrants from ancient Korea.
桂川を大堰川と呼ぶ名称は、古代朝鮮から渡来人である秦氏がつくった農業用の「堰」に由来する。