Llandderfel is a Welsh parish within the ancient district of Penllyn which was formed in the 1985 when the old parishes of Llanfor and Llandderfel were united under the same council. Despite being one of the largest parishes in Wales, with an area of nearly twenty thousand hectares - stretching from Conwy Council’s boundary in the north to Denbighshire in the north east and to the south east boundary of Powys, it is also one of the least populated with only 1,511 inhabitants dispersed across the six villages of Llandderfel, Glanrafon, Llanfor, Frongoch, Cefnddwysarn and Sarnau of which nearly three quarters are Welsh speaking. Renowned for its Welsh culture and picturesque landscape, Llandderfel is a tranquil parish of rivers with the Dyfrdwy (river Dee) running through its centre, and with its tributaries, the Celyn and Tryweryn forming much of western and southern boundaries. It was not always so tranquil, in the sixties the valley was controversially dammed, flooding a Welsh speaking village to form a reservoir to supply Liverpool industry - water which, in the end, was never needed. Although the main business of the parish is agriculture, walkers are attracted by the three mountain peaks of Carnedd y Filiast (669 meters), Foel Cwm Sian Llwyd (648 meters), and Foel Goch (611 meters).