Stwlan Dam is a mountain reservoir at an elevation of 510m (1,673ft) above the sea level, located in Gwynedd, north-west Wales, United Kingdom.
Located within the Snowdonia National Park, the road to the Ffestiniog Power Station is paved. Starting from the city of Tanygrisiau, Llyn Stwlan is reached by a narrow 2.86 km (1.78 mi) long winding road with six hairpins bends. The elevation gain is 275 meters. The average gradient is 9.61%. At the top, the views of the Moelwyn range and the Vale of Ffestiniog are outstanding. Footpaths and a road (closed to cars) lead to Llyn Stwlan from Tanygrisiau, where there are car parks.
Chains or snow tyres can be required anytime. Llyn Stwlan was a small, corrie lake until the late 1950s when the dam was built as part of the Ffestiniog Hydro-Electric pumped storage scheme. Lying 1,600 feet above sea level in the Moelwyn mountains, Stwlan is the top reservoir from which the water drops 1,000 feet to turn turbines at the Ffestiniog Power Station.
Pic: Gareth Jones