Lake Vyrnwy

{{Use dmy dates|date=June 2015}}

{{Use British English|date=June 2015}}

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{{More citations needed|date=September 2008}}

{{Travel guide|date=July 2013}}

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{{short description|Man-made lake in Wales}}

{{Infobox body of water

| name = Lake Vyrnwy

| other_name = {{langx|cy|Llyn Efyrnwy}}

| image = Lakevyrnwysummer.jpg

| caption = View overlooking Lake Vyrnwy showing the full extent of the lake

| image_bathymetry =

|pushpin_map=Wales Powys

| caption_bathymetry =

| location = Wales

| coords = {{coord|52.78|N|3.50|W|region:GB_type:waterbody|display=inline,title}}

| lake_type = Reservoir

| inflow = River Vyrnwy and other small streams

| outflow = River Vyrnwy

| catchment =

| date-built = 1881–88

| date-flooded =

| agency = Hafren Dyfrdwy
subsidiary of Severn Trent

| length = {{convert|4.75|mi|km|order=flip}}

| width = {{convert|0.5|mi|km|order=flip}}

| area = {{convert|1121|acre|km2|order=flip}}

| depth =

| max-depth = {{convert|84|ft|m|order=flip}}

| volume = {{convert|13.125|e9impgal|GL|sigfig=3|order=flip}}

| shore = {{convert|12|mi|km|order=flip}}

| elevation =

}}

Lake Vyrnwy ({{langx|cy|Llyn Efyrnwy}}, {{IPA|cy|ɛˈvərnʊɨ|pron}} or {{lang|cy|Llyn Llanwddyn}}) is a reservoir in Powys, Wales, built in the 1880s for Liverpool Corporation Waterworks to supply Liverpool with fresh water. It flooded the head of the Vyrnwy ({{langx|cy|Afon Efyrnwy}}) valley and submerged the village of Llanwddyn.

The Lake Vyrnwy Nature Reserve and Estate that surrounds the lake is jointly managed by the Royal Society for the Protection of Birds (RSPB) and Hafren Dyfrdwy and is a popular destination for ornithologists, cyclists and hikers. The reserve is designated as a national nature reserve, a Site of Special Scientific Interest, a Special Protection Area, and a Special Area of Conservation.

Geography

Lake Vyrnwy is a reservoir in Powys, Wales, created in 1888 by flooding the head of the River Vyrnwy ({{langx|cy|Afon Efyrnwy}}) valley.

The river flows from the dam into Shropshire where it converges with the River Severn near the village of Melverley on the Welsh border and outflows into the Bristol Channel.

When the reservoir is full, it is {{convert|84|ft|m|order=flip}} deep, contains {{convert|13.125|e9impgal|Gl|sigfig=3|order=flip}}, and covers an area of {{convert|1121|acre|km2|order=flip}},{{cite journal |title=Lake Vyrnwy |journal=The Practical Engineer |date=1891 |volume=V |url=http://www.gracesguide.co.uk/1891_The_Practical_Engineer#LAKE_VYRNWY |access-date=11 June 2014 |publisher=Technical Publishing Company }} the equivalent of around 600 football pitches. The lake has a perimeter of {{convert|12|mi|km|order=flip}} with a road that goes all the way around it. Its length is {{convert|4.75|mi|km|order=flip}}.

311 brooks, waterfalls and rivers flow into the lake and are named after the mountains or hillsides they flow from. The main ones, clockwise from the west side of the dam, are named Afon Hirddu, Eunant, Afon Eiddew, Afon Naedroedd, Afon Cedig and Afon Y Dolau Gwynionew.

On the northern edge of the lake is a small hamlet called Rhiwargor where the rivers Afon Eiddew and Afon Naedroedd meet. Up the valley of Afon Eiddew is a waterfall known locally as Pistyll Rhyd-y-meincau, commonly known as Rhiwargor waterfall.

=Climate=

{{Weather box

|location = Lake Vyrnwy No 2, Elevation: {{convert|360|m|ft|0|abbr=on}}, 1991–2020 normals

|metric first = Yes

|single line = Yes

|width = auto

|Jan high C = 5.7

|Feb high C = 6.0

|Mar high C = 7.9

|Apr high C = 10.7

|May high C = 13.7

|Jun high C = 16.3

|Jul high C = 18.0

|Aug high C = 17.5

|Sep high C = 15.3

|Oct high C = 11.7

|Nov high C = 8.4

|Dec high C = 6.3

|year high C =

|Jan mean C = 3.4

|Feb mean C = 3.5

|Mar mean C = 5.0

|Apr mean C = 7.1

|May mean C = 10.0

|Jun mean C = 12.7

|Jul mean C = 14.4

|Aug mean C = 14.2

|Sep mean C = 12.2

|Oct mean C = 9.1

|Nov mean C = 6.1

|Dec mean C = 4.0

|year mean C =

|Jan low C = 1.2

|Feb low C = 1.0

|Mar low C = 2.0

|Apr low C = 3.6

|May low C = 6.2

|Jun low C = 9.0

|Jul low C = 10.9

|Aug low C = 10.9

|Sep low C = 9.1

|Oct low C = 6.6

|Nov low C = 3.8

|Dec low C = 1.7

|year low C =

|precipitation colour = green

|Jan precipitation mm = 190.1

|Feb precipitation mm = 162.5

|Mar precipitation mm = 127.0

|Apr precipitation mm = 96.8

|May precipitation mm = 99.9

|Jun precipitation mm = 98.6

|Jul precipitation mm = 98.7

|Aug precipitation mm = 110.4

|Sep precipitation mm = 121.2

|Oct precipitation mm = 179.9

|Nov precipitation mm = 179.4

|Dec precipitation mm = 214.5

|year precipitation mm =

|unit precipitation days = 1.0 mm

|Jan precipitation days = 18.3

|Feb precipitation days = 14.9

|Mar precipitation days = 15.2

|Apr precipitation days = 13.3

|May precipitation days = 13.4

|Jun precipitation days = 12.6

|Jul precipitation days = 13.6

|Aug precipitation days = 14.7

|Sep precipitation days = 14.1

|Oct precipitation days = 17.5

|Nov precipitation days = 18.8

|Dec precipitation days = 19.1

|year precipitation days = 185.3

|Jan sun = 42.7 |Jan percentsun =

|Feb sun = 62.5 |Feb percentsun =

|Mar sun = 104.6 |Mar percentsun =

|Apr sun = 145.5 |Apr percentsun =

|May sun = 177.5 |May percentsun =

|Jun sun = 163.7 |Jun percentsun =

|Jul sun = 168.4 |Jul percentsun =

|Aug sun = 151.1 |Aug percentsun =

|Sep sun = 118.9 |Sep percentsun =

|Oct sun = 83.7 |Oct percentsun =

|Nov sun = 51.4 |Nov percentsun =

|Dec sun = 38.3 |Dec percentsun =

|year sun = 1308.4

|source = Met Office{{cite web

| url = https://www.metoffice.gov.uk/research/climate/maps-and-data/uk-climate-averages/gcms1hjef

| title = Lake Vyrnwy Climate

| accessdate = 25 April 2024

|publisher = Met Office}}

}}

Construction

File:Building the dam, Llanwddyn NLW3361918.jpg

File:Lake Vyrnwy Dam.jpeg

File:Vyrnwy Dam.JPG

File:Rhiwargor Falls, Lake Vyrnwy, Powys, Wales.jpeg

In 1879, George Deacon was instructed to prepare the parliamentary plans for the Vyrnwy Dam. The valley was chosen because of its size, favourable geology and its source, the River Vyrnwy, having a large water catchment area.{{citation needed|date=November 2019}}

Thomas Hawksley was appointed as engineer-in-chief and prepared the design for a stone dam.{{cite ODNB|last1=Beare|first1=T H|title=Thomas Hawksley (1809-1893)|url=http://www.oxforddnb.com/view/article/12691|year=2004 |doi=10.1093/ref:odnb/12691 |access-date=7 November 2017}} Dam construction with great blocks of Welsh slate started in 1881 and was completed in 1888. Hawksley resigned in 1885 because of a conflict with George Deacon who was appointed as joint engineer.{{citation needed|date=November 2019}} The dam was the first large stone-built dam in the United Kingdom{{citation needed|date=November 2019}} and cost £620,000 (equivalent to £{{Inflation|UK-GDP|0.62|1888|r=-1}} million in {{Inflation-year|UK-GDP}}{{Inflation-fn|UK-GDP}}).{{citation needed|date=November 2019}} Earlier dams in Britain had been built using great earth embankments to hold back the water.{{citation needed|date=November 2019}} In 1889, shortly after completion, the lake was stocked with 400,000 Loch Leven trout.

Between 1881 and 1892 the aqueducts carrying water to Liverpool were constructed.{{citation needed|date=November 2019}}

Construction of the dam flooded the village of Llanwddyn. The residents of the village were not consulted about the proposal for a dam and opposed the plan. Their relocation involved the demolition of a church, two chapels, three inns, ten farmhouses, and 37 houses. A new settlement to house them was built lower down the valley by Liverpool Corporation.{{cite news | last = Hadfield | first = Charlotte | title = Remains of lost village hidden beneath reservoir used to supply Liverpool with drinking water | newspaper = Liverpool Echo | location = Liverpool | date = 11 October 2020 | url = https://www.liverpoolecho.co.uk/news/liverpool-news/remains-lost-village-hidden-beneath-19076569 }}

Description

The Vyrnwy dam is {{convert|44|m|ft}} high from the bottom of the valley, and {{convert|39|m|ft}} thick at the base; it is {{convert|358|m|ft}} long and has a road bridge running along the top. It is decorated with 31 arches each spanning {{convert|7.3|m|ft}} and two small towers each with four corner turrets rising {{convert|14|ft|m|order=flip}} above the road surface. The dam was the first to be constructed with drainage tunnels designed to prevent a build up of pressure beneath the base. It is listed as a Grade I historic building by Cadw.{{Coflein | desc = Lake Vyrnwy Dam, Llanwddyn | num = 32442 | mode = cs2 | access-date = 2021-04-24 }}{{Citation | title = Lake Vyrnwy Dam | publisher = British Listed Buildings | url = https://britishlistedbuildings.co.uk/300015621-lake-vyrnwy-dam-llanwddyn#.YIR0JybTX0o | access-date = 2021-04-24 }}

The dam was the first to carry water over its crest instead of in a channel at the side. At the bottom of the dam is a body of water known as a stilling basin necessary to absorb the energy when the water flows over the crest and into the valley, and to stop the water eroding the foundations of the dam.

A power house located under the west tower contains an electrical generator driven by water leaving the reservoir. Before mains electricity arrived in the 1960s this was the area's only source of power.

About {{convert|0.75|mi|m|sigfig=2|order=flip}} from the dam is the reservoir's straining tower. Standing only {{convert|98|ft|m|order=flip}} from the shore, its purpose is to filter or strain out material in the water with a fine metal mesh, before the water flows along the aqueduct to Liverpool. Its architecture represents Gothic revival, built at the same time as the dam. The tower as a whole is {{convert|154|ft|m|order=flip}} tall, {{convert|104|ft|m|order=flip}} of which is above top water level, and is topped with a pointed copper-clad roof, coloured light green.

The west and east towers release compensation water into the River Vyrnwy through huge valves; the river would dry up unless a minimum flow was maintained. Depending on the levels downstream, the reservoir can release from {{convert|25|to|45|Ml|e6impgal|abbr=off|round=5}} of compensation water daily. The flow is measured by Natural Resources Wales at a weir a few hundred metres downstream.

File:Llyn Llanwddyn - Vyrnwy Dam, Powys, Wales built over a village to supply water to Liverpool 45.jpg

Water supply

=19th century=

The water from Lake Vyrnwy is carried {{convert|68|mi|km|order=flip}} in the Vyrnwy Large Diameter Trunk Main (LDTM) aqueduct which originally consisted of two pipelines, made largely of cast iron. To help maintenance work on the {{convert|9|ft|m|order=flip}} diameter cast-iron tunnel which took the aqueduct under the Mersey, riveted steel piping was also used, which was to become the norm for trunk water-main piping.

The aqueducts cross the valley floor near Penybontfawr and then runs north of Llanrhaeadr-ym-Mochnant and Efail-rhyd on the north-east of the Tanat Valley. The aqueducts are largely underground although there are some visible surface features including air valves, the Cileos valve house, the Parc-uchaf balancing reservoirs, and a deep cutting to the west of Llanrhaeadr-ym-Mochnant.

Brick and concrete-lined tunnels carried pipes at Hirnant, Cynynion and Llanforda, and a fourth was later added at Aber, so that the Hirnant tunnel could be made accessible for maintenance.

=20th century=

From 1926 to 1938 the first section of a third pipeline was laid using bituminous-coated steel.{{Cite web |url=http://engineering-timelines.com/scripts/engineeringitem.asp?id=388 |title=Engineering Timelines - Vyrnwy Aqueduct (1892) |date=nd |website=engineering-timelines.com |access-date=2019-11-03}} in 1946, a fourth pipeline was added south of Oswestry to increase capacity to 227 million litres per day.

In 1978–81, the pipe crossings beneath the Mersey and the Manchester Ship Canal were reorganised.

After privatisation of the water companies, responsibility for the Vyrnwy Dam and associated structures fell to Severn Trent Water, and since 2018 to its subsidiary company Hafren Dyfrdwy.

The rights to the water abstraction are with United Utilities for drinking water supply to Liverpool.

=21st century=

In 2013, United Utilities commenced a major refurbishment of the entire {{cvt|240|km}} of the LDTM aqueduct, which was scheduled for completion in 2020.{{cite web |url=http://www.unitedutilities.com/vyrnwy.aspx |title=Vyrnwy water pipe works |website=United Utilities |access-date=3 July 2013 |archive-url=https://web.archive.org/web/20140818134610/http://www.unitedutilities.com/vyrnwy.aspx |archive-date=18 August 2014 |url-status=dead |df=dmy-all }}

As of 2014 water provision relied on three parallel, 80 km long gravity pipelines, {{convert|42|in|m|order=flip}} in diameter delivering up to {{convert|50|e6impgal|m3|order=flip}} per day into reservoirs at Prescot, east of Liverpool, which supplied customers in Cheshire and Merseyside.{{Cite web |url=https://www.waterprojectsonline.com/case_studies/2014/UU_Vyrnwy_2014.pdf |archive-url=https://web.archive.org/web/20191103224404/https://www.waterprojectsonline.com/case_studies/2014/UU_Vyrnwy_2014.pdf |archive-date=3 November 2019 |title=Vyrnwy Aqueduct Refurbishment |first=Kevin |last=Harvey |date=2014 |website=WaterProjectsOnline.com}}

Nature reserve and conservation

{{unreferenced section|date=June 2013}}

Lake Vyrnwy is a designated Nature Reserve. The RSPB has several bird hides around the lake, where a number of rare species of birds are known to be breeding, including the peregrine falcon, the pied flycatcher, the common redstart, the Eurasian siskin and the wood warbler. Every spring they host a dawn chorus tour.

Around 90 species of bird have been recorded as breeding on the reserve, and six species of bat, including the pipistrelle and brown long-eared bat. Butterfly species include purple hairstreaks, commas and peacocks. Dragonflies include golden ringed, common hawker and four spotted chaser.

Managing the moorland helps improve the habitat for red grouse and the short-eared owl.

Heather moorland which grows on the mountains around the lake is now{{when|date=November 2019}} being restored. In the past, heather was burnt, cut and the seeds collected to be sowed where the heather has gone. Burning at the Lake Vyrnwy moorland is no longer carried out, as the burning can have negative consequences for water management, namely water colouration.

Sheep, cattle and ponies also graze on the heather, managed by tenant farmers who farm the moorland in accordance with organic agriculture.

Broadleaf trees are being planted to replace coniferous trees, and man-made features such as hedgerows and dry-stone walls are also being restored, and wildflower areas are being restored to help insects, birds and other wildlife.

Tourism

=Wood sculpture=

Llanwddyn has had since 1995 a sculpture park in the valley below the dam, containing many wooden carved works. There are large wooden picnic benches in the shape of leaves and trees on the west side of the lake at Llechwedd Ddu. Near the old village on the beach is a sculpture of dolphins which, when the lake rises in a flood, appear to be jumping out of the water. Several totems are carved into standing trees and re-erected fallen trunks.{{cite web |url=http://www.glyn-yr-aur.com/vyrnwy.htm |archive-url=https://web.archive.org/web/20140222061531/http://www.glyn-yr-aur.com/vyrnwy.htm |url-status=dead |archive-date=22 February 2014 |title=The Sculpture Park at Vyrnwy |website=Glyn-yr-Aur |access-date=3 July 2013 }}

=Recreation=

Activities in the area include sailing, hiking on Glyndŵr's Way, rock climbing, cycling, walking and horse riding.{{cite web|url=http://positivelynorthwales.com/2016/03/29/lake-vyrnwy/|title=Lake Vyrnwy|date=29 March 2016|website=positivelynorthwales.com}} The Lake Vyrnwy Half Marathon is conducted annually. The RSPB have laid out seven waymarked trails ranging from {{convert|1|to|5.5|mi|km|sigfig=1|order=flip}} in a range of habitats.

=Tallest tree=

The site was once home to the tallest tree in the UK, a Douglas Fir {{convert|63.79|m|ft}} high. This was damaged in stormy weather during the winter of 2010-2011 and had to be felled at 124 years old in March 2011. A {{convert|15.2|m|ft}} stump was left intact, which in autumn 2011 had its top carved into a {{convert|2|m|ft}} tall giant outstretched hand.{{Cite news|date=2011-11-11|title=Ex-tallest tree carved into hand|language=en-GB|work=BBC News|url=https://www.bbc.com/news/uk-wales-mid-wales-15693962|access-date=2020-07-27}} A nearby Douglas Fir is now, at {{convert|60.62|m|ft}}, the tallest tree in Wales.{{cite web |url=http://www.forestry.gov.uk/newsrele.nsf/WebPressReleases/ABC2451E23A96EBB8025785A0037C721 |archive-url=https://web.archive.org/web/20140106110910/http://www.forestry.gov.uk/newsrele.nsf/WebPressReleases/ABC2451E23A96EBB8025785A0037C721 |url-status=dead |archive-date=6 January 2014 |title=Neighbour inherits 'tallest tree' title |access-date=15 March 2014 }}

References

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