Llyn Brianne

The dam is of crushed rock, larger rock and clay; all materials having been obtained in the area. In essence, it is a constructed mountain blocking the valley. The clay was harvested higher up the valley near Soar y mynydd chapel closer to Tregaron. Much of the rock was harvested at the site. An on-site stone-crusher was used to reduce larger rocks to the various sizes required. A round-the-clock labouring system enabled its completion almost two years ahead of schedule.