Bala Lake ([ˈbala]; Welsh:Llyn Tegid, [ˈɬɨ̞n ˈtɛɡɨd]; also often known as Llyn Tegid to English speakers) is a lake in Gwynedd, Wales. The name Tegid may be related to Welsh teg, meaning "fair". It was the largest natural body of water in Wales before its level was raised by Thomas Telford to help support the flow of the Ellesmere Canal. It is 3.7 miles (6.0 km) long by 0.5 miles (0.8 km) wide, and is subject to sudden and dangerous floods. The River Dee runs through it and the waters of the lake are famously deep and clear. The town of Bala sits at its north-eastern end and the narrow gauge Bala Lake Railway runs for 5 km (3 miles) along the lake's south-eastern shore, and continues south-westward to the village of Llanuwchllyn (whose name means "above the lake").