Llyn Cowlyd

Llyn Cowlyd is the deepest lake in northern Wales. It is a reservoir in the Snowdonia National Park at the upper end of Cwm Cowlyd on the south-eastern edge of the Carneddau range of mountains, at a height of 370 metres (1,210 ft) above sea level. The lake is long and narrow, measuring 3.0 kilometres (1.9 mi) long and up to about 400 metres (440 yd) wide, and covers an area of about 1.1 square kilometres (270 acres). It has a mean depth of 33 metres (108 ft) and at its deepest has given soundings of 70 metres (230 ft), this being some 14 m (46 ft) greater than its natural depth, the water surface having been raised twice by the building of dams.

The surrounding hills drop steeply to the water's edge, from Cefn Cyfarwydd and Creigiau Gleision to the east, and Pen Llithrig y Wrach to the west, and as a consequence have not been forested in the 20th century, as were the slopes of neighbouring Llyn Crafnant. Indeed, there is not a tree to be seen, and the general aspect is one of bleakness. Dependent on the weather conditions, the waters often appear dark.

The supply of water to Llyn Cowlyd is assisted at its south-western end by a leat which runs roughly east–west, following the 418 metres (1,371 ft) contour, to the south and west of the lake, along the Llugwy valley. It is also fed by water from Llyn Eigiau.^{[dubious – discuss]}

Llyn Cowlyd can be reached by road from Trefriw, some 5 kilometres (3 mi) to the east, although the metalled road stops at a gate, around 1.2 km or 0.75 miles from the lake, beyond which private vehicles are not permitted. Llyn Cowlyd can also be reached by foot from Capel Curig, some 3.5 kilometres (2.2 mi) to the south, from the ridge of Cefn Cyfarwydd, or from above Dolgarrog. A good path runs along the north-western shore of the lake.

The stream which flows from Llyn Cowlyd, beyond the dam at the north-eastern end of the lake, is called Afon Ddu. This flows into the river Conwy, passing Pont Dolgarrog on the B5106 road, just south of the village of Dolgarrog. The gorge cut by the river at this point is popular for gorge walking.

Some sources state that the name Cowlyd comes from "Cawlwyd" or "Cawllwyd". Algernon Herbert's book Britannia after the Romans refers to Caw, Lord or Chieftain of Cwm Cawllwyd. "Cwm Cawllwyd" could therefore translate as The Cwm of Grey Caw.

Further research suggests that the name might derive originally from Caw ap Geraint Llyngesog ab Erbin ap Custennin Gorneu ap Cynfor ap Tudwal, the famous warrior who features in Culhwch and Olwen. Caw's son Celyn ap Caw had a watchtower, Tŵr Celyn, near the Copper mountain, on Anglesey.

The Ordnance Survey map of 1841 records the name as "Cwlyd", as does the National Gazetteer of 1868.[1]