In the Nihon Kiryaku (historical books written in the Heian period), the Kamogawa River is written as 鴨川 or 賀茂川, but this does not indicate that people at that time distinguished between the two notations according to the part of the river.
「日本紀略」では「鴨川」「賀茂川」どちらの表記も混在しているが、平安時代には流域により表記を区別していたわけではない。