The Clywedog river is dammed high above Llanidloes forming a large reservoir popular with anglers and the local sailing club. The dam is used to regulate flow of water down the river and into the Severn. Occasionally the water overflows the top of the dam forming a spectacular backdrop to the Bryntail lead mine at its foot.
To reach Clywedog from Wye View take the second exit from the Llangurig roundabout towards Llanidloes. At the next roundabout take the first exit for Llanidloes. Immediately after the filling station on the right hand side, take the third exit at the roundabout and cross the river. Take the first left, signposted Machynlleth. Follow the B4518 for two miles then take turning on the left signposted Llyn Clywedog. Bryntail lead mine is signposted on the right after around a quarter of a mile, and the track to the top of the dam is just beyond, also on the right.
You can continue to drive around the whole reservoir, or follow signs to the Hafren forest and the source of the Severn.