Its tributary is the Afon Tafolog, which drains the eastern slopes of Drum, a mountain in the Carneddau range.
The river flows through the village of Rowen before joining the River Conwy.
Course
The river originates from several small streams on the southern slopes of Tal y Fan, to the east of Bwlch y Ddeufaen. The highest of these streams originates approximately 480 meters up just south of the western summit of Tal y Fan. Other streams come from a little to the east and flow close to the old Poet's Stone (Maen y Bard). After following a southern course they join to form the river Ro. The Tafolog River, which gathers a number of mountain streams in the marshland near Bwlch y Deufaen, joins the river which then flows on a course in a north-eastern direction.
It flows through the village of Rowen and then makes a turn to flow in a southern direction. It goes under a bridge and past the village of Caerhun. It turns east again passing the site of the Roman fort of Canovium to flow into the River Conwy at the end.[2]
