River Banwy

The river rises in the hills near the pass which takes the A458 between Mallwyd and Welshpool. The river is called Nant Cerrig-y-groes at its source near Moel y Llyn. It then flows east, and joins a number of lesser streams before reaching Pont Twrch near the village of Y Foel, at its confluence with the river Twrch.

Two miles further on, it is joined by the river Gam, which flows down from the Nant yr Eira, between Y Foel and Llangadfan.