Llyn Peris is a

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

Snowdonia Snowdonia or Eryri (), is a mountainous region in northwestern Wales and a national park of in area. It was the first to be designated of the three national parks in Wales, in 1951. Name and extent It was a commonly held belief that the nam ...

, Wales, approximately 1.8 km long and situated close to the villages of

Llanberis (; ) is a village, community and electoral ward in Gwynedd, northwest Wales, on the southern bank of the lake and at the foot of Snowdon, the highest mountain in Wales. It is a centre for outdoor activities in Snowdonia, including walking, mo ...

and Nant Peris, and the smaller twin of

Llyn Padarn Llyn Padarn is a glacially formed lake in Snowdonia, Gwynedd, north Wales, and is an example of a moraine dammed lake. The lake is approximately long (about 240 acres) and at its deepest point is deep, and is one of the largest natural lakes i ...

. The lake was formed glacially and is an example of a

moraine-dammed lake A moraine-dammed lake occurs when the terminal moraine has prevented some meltwater from leaving the valley. Its most common shape is that of a long ribbon (ribbon lake). Example of moraine dammed lakes include: *Argentina/Chile: General Carre ...

. Llyn Peris is named after Saint Peris, an early Christian saint of whom little is known. The lake is flanked on one side by the mountain

Elidir Fawr Elidir Fawr is a mountain in Snowdonia, north Wales, the northernmost peak in the Glyderau. Its name means 'Big Elidir', named after a legendary warrior king of the 6th century also known as Eliffer Gosgorddfawr (Elidir of the Great Army). To ...

and the former slate quarry of

Dinorwig Dinorwig sometimes spelled Dinorwic ( ; ; ), is a village located high above Llyn Padarn, near Llanberis, in Wales. The name is shared with the fort of Dinas Dinorwig, also within the community of Llanddeiniolen, on a foothill from Dinorwig v ...

. Above the opposite bank are the hills of Derlwyn and Clogwyn Mawr and a rock formation known as the Lady of Snowdon, due to its resemblance to a human face. The ruins of

Dolbadarn Castle Dolbadarn Castle ( ; cy, Castell Dolbadarn ) is a fortification built by the Welsh prince Llywelyn the Great during the early 13th century, at the base of the Llanberis Pass, in northern Wales. The castle was important both militarily and a ...

are also located on a mound above the lake. The lake now forms the lower reservoir of Dinorwig power station, and the administrative buildings for the station are situated on the lake shore. Water is released into the lake from Marchlyn Mawr (the upper reservoir) to produce electricity during periods of peak demand. This water is, in turn, pumped back to the upper reservoir using electricity purchased at off-peak periods. The water level of the lake therefore varies considerably, depending on UK electricity demand. Excess water from the lake drains into

. During construction of the power station, when the capacity of the lake was increased considerably at this time, with the removal of a large quantity of slate waste, rare Welsh

Arctic char The Arctic char or Arctic charr (''Salvelinus alpinus'') is a cold-water fish in the family Salmonidae, native to alpine lakes and arctic and subarctic coastal waters. Its distribution is Circumpolar North. It spawns in freshwater and populatio ...

fish were removed to four other lakes in the neighbouring

Carneddau The (lit. 'the cairns'; is a Welsh plural form, and is sometimes anglicised to ''Carnedds'') are a group of mountains in Snowdonia, Wales. They include the largest contiguous areas of high ground (over or high) in Wales and England (although l ...

mountains, namely Ffynnon Llugwy,

Llyn Cowlyd Llyn Cowlyd is the deepest lake in northern Wales. It lies 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 above sea level. The lake is long and narrow ...

Llyn Melynllyn Llyn Melynllyn (Welsh for ''yellow lake'') is a lake within the Carneddau range of mountains in Snowdonia, North Wales. It lies at a height of just over , and has an area of some . Cliffs rise steeply from its western edge, up to the summit of ...

and

Llyn Dulyn Llyn Dulyn ( cy, black lake) is a lake on the edge of the Carneddau range of mountains in Snowdonia, North Wales. The lake is in extent and 189 feet (58 metres) deep. Less than a kilometre to its south lies the smaller Llyn Melynllyn. Cliffs ri ...

, where they are still to be found. Although Llyn Peris itself was not restocked, some char have found their way back to the lake. Parts of the lake shore are designated as a

Site of Special Scientific Interest A Site of Special Scientific Interest (SSSI) in Great Britain or an Area of Special Scientific Interest (ASSI) in the Isle of Man and Northern Ireland is a conservation designation denoting a protected area in the United Kingdom and Isle of ...

for Glacial Geology.

External links

Dinorwig Power Station
{{authority control Llanberis Llanddeiniolen Peris Tourism in Gwynedd Sites of Special Scientific Interest in West Gwynedd