Clywedog Reservoir | |
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Location | Llanidloes, Powys Trefeglwys, Powys |
Coordinates | 52°29′10″N3°37′30″W / 52.48611°N 3.62500°W |
Type | reservoir |
Primary inflows | Afon Clywedog |
Primary outflows | Afon Clywedog |
Basin countries | Wales |
Max. length | 9.5 km (5.9 mi) |
Surface area | 2.5 km2 (0.97 sq mi) |
Max. depth | 66 m (217 ft) |
Water volume | 50,000 megalitres (41,000 acre⋅ft) |
The Clywedog Reservoir (Welsh : Llyn Clywedog) is a reservoir near Llanidloes, Wales on the head-waters of the River Severn. The construction of the reservoir was enabled by an act of Parliament, the Clywedog Reservoir Joint Authority Act 1963 (c. xxxi), which asserted that "At certain times the flow of water in the river is inadequate ... unless that flow were regulated so as to ensure that at those times water in addition to the natural flow will flow down the river." [1]
Its primary purpose was to regulate the flow in the River Severn [2] [3] to mitigate flooding and provide support for drinking water abstractions for the West Midlands. [4] [5] [6] It was completed in 1967 and is situated near the B4518 road north of Llanidloes, Powys. [7] [3] [8]
It regulates the flow of water in the River Severn by releasing water into the river channel during low flow periods and re-filling during the wetter winter months. This enables major water abstractions to be made from the River Severn to supply the West Midlands with 50 million litres (11,000,000 imp gal) of drinking water. Capacity is held in the reservoir throughout the winter so that it retains capacity to mitigate downstream flooding by absorbing excess flow from the head-waters of the Afon Clywedog, a tributary of the River Severn. The reservoir was formed by damming both the Afon Clywedog and a much smaller embankment dam located at Bwlch-y-gle to prevent overflow into the next valley. Its concrete buttress dam is the tallest concrete dam in the UK, with a height of 72 metres (236 ft) and a length of 230 metres (750 ft). When at capacity the reservoir contains approximately 50,000 megalitres of water.
Clywedog Reservoir Joint Authority Act 1963 | |
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Act of Parliament | |
Long title | An Act to constitute the Clywedog Reservoir Joint Authority consisting of representatives of the lord mayors, aldermen and citizens of the cities of Birmingham and Coventry, the mayors, aldermen and burgesses of the boroughs of Shrewsbury and Wolverhampton, the mayor, aldermen and citizens of the city of Worcester, the Bristol Waterworks Company, the Central Electricity Generating Board, the Cheltenham and Gloucester Joint Water Board, the East Shropshire Water Board, the East Worcestershire Waterworks Company, the Montgomeryshire Water Board, the South Staffordshire Waterworks Company, the county council of the administrative county of Montgomery and the Severn River Board, to empower the Clywedog Reservoir Joint Authority to acquire lands, to construct works and to regulate the flow of water in the river Severn; to confer powers upon the constituent authorities of the said Authority; and for other purposes. |
Citation | 1963 c. xxxi |
Dates | |
Royal assent | 31 July 1963 |
Text of statute as originally enacted |
Construction of the dam started in 1963 and finished in 1967 after the passing of an act of Parliament, the Clywedog Reservoir Joint Authority Act 1963 (c. xxxi), ordering its creation to help prevent flooding of the River Severn in winter and to maintain its water levels in the summer. Local opposition was strong against the construction of the reservoir as it would result in the flooding of much of the Clywedog valley and the drowning of 615 acres (2.5 km2) of agricultural land. On top of several disruptions and protests, during construction in 1966 a bomb was detonated within the construction site, setting work back by almost two months. The political extremist group Mudiad Amddiffyn Cymru (MAC) was widely suspected of carrying out the bombing. [9]
The reservoir was opened in 1967 and has been in continuous usage since then, generally filling with water over the winter months and gradually releasing it during the summer months. The reservoir is currently owned and operated by Severn Trent (the successors to the Clywedog Reservoir Joint Authority) with oversight and regulation by Natural Resources Wales. Clywedog Sailing Club operates on the lake, and Powys County Council's Staylittle Outdoor Centre delivers a range of adventure education both on the water and in the surrounding area.
The dam operating plant runs self-sufficiently from a 500 kW hydro-electric turbine. The area around Clywedog dam is now a popular leisure destination offering scenic walks and wildlife watching. At the base of the dam lies the ruins of the Bryntail lead mine. In 2005 Natural Resources Wales installed an osprey nest platform near the reservoir. The nest has been in use by breeding ospreys since 2014; by the end of 2022, 22 osprey chicks had been raised on the site. [10] A web camera was installed in 2020 enabling video of the nest to be viewed online. [11] A trout fishery operates on the reservoir. [12]
Powys is a county and preserved county in Wales. It borders Gwynedd, Denbighshire, and Wrexham to the north; the English ceremonial counties of Shropshire and Herefordshire to the east; Monmouthshire, Blaenau Gwent, Merthyr Tydfil, Caerphilly, Rhondda Cynon Taf, and Neath Port Talbot to the south; and Carmarthenshire and Ceredigion to the west. The largest settlement is Newtown, and the administrative centre is Llandrindod Wells.
Llanidloes is a town and community on the A470 and B4518 roads in Powys, within the historic county boundaries of Montgomeryshire, Wales. The population in 2011 was 2,929, of whom 15% could speak Welsh. It is the third largest settlement in Montgomeryshire, after Newtown and Welshpool.
Lake Vyrnwy 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 valley and submerged the village of Llanwddyn.
The River Towy is one of the longest rivers flowing entirely within Wales. Its total length is 120 km (75 mi). It is noted for its sea trout and salmon fishing.
The Desert of Wales, or Green Desert of Wales, is an archaic term for an area in central Wales, so called for its lack of roads and towns, and its inaccessibility. The term was coined by English travel writers in the nineteenth century and has no equivalent in the Welsh language. The area corresponds roughly to the upland area called Elenydd in Welsh.
The Dee regulation scheme is a system of flow balancing and quality management along the River Dee managed by a consortium of the three largest water companies licensed to take water from the river, United Utilities, Welsh Water and Severn Trent Water; together with the regulator, Natural Resources Wales.
The River Dwyryd, is a river in Gwynedd, Wales which flows principally westwards; draining to the sea into Tremadog Bay, south of Porthmadog.
Llyn Brenig is a reservoir located on Denbigh Moors in North Wales. The artificial lake, which was constructed between 1973 and 1976, was created by building an embankment dam across the Afon Brenig valley. It lies at 1,200 ft (370 m) above sea level on the border between the counties of Conwy and Denbighshire. It is used to manage the flow in the River Dee as part of the River Dee regulation system.
A reservoir is an enlarged lake behind a dam, usually built to store fresh water, often doubling for hydroelectric power generation.
Clywedog may refer to:
Llyn Brianne is a man-made lake or reservoir in the headwaters of the River Towy in Wales.
Hafren Forest lies north-west of Llanidloes, an ancient market town in Mid Wales.
Staylittle, sometimes referred to colloquially as Y Stay or Y Stae, is a small village set in the shallow upland basin of the Afon Clywedog on the B4518 road, equidistant from Llanidloes and Llanbrynmair in the historic county of Montgomeryshire, Wales, although now administered as part of the unitary authority of Powys.
Coedty Reservoir is a reservoir in Snowdonia, North Wales. It is fed by the waters of Afon Porth-llwyd which flows from Llyn Eigiau. The reservoir lies at a height of 900 feet (274 m), and measures some 12 acres (49,000 m2) in size. It contains brown trout.
Bryntail lead mine is a disused lead mine near Llanidloes in Powys, Wales. Sited on the Afon Clywedog and in the shadow on the Clywedog reservoir dam, it is in the care of Cadw.
The Afon Clywedog is an upland headwater tributary of the River Severn in Powys, Wales. It is approximately 29 km long and has its source on the flanks of Plynlimon and has its confluence with the Severn in Llanidloes. The annual rainfall over the catchment is between 1737 mm and 1836 mm.
The Afon Dulas is a river in Powys, Wales. It is a headwater tributary of the River Severn, which it joins at Llanidloes opposite the confluence with the Afon Clywedog. Its principal tributary is the Afon Brochan. The total length of the Dulas and Brochan is 19.6 km. Other tributaries include Nant Cydros, the Rhydyclwydau Brook and Nant Gynwydd.
Llanidloes Without is a rural community in north Powys (Montgomeryshire), Wales. Settlements within the community include Van, Oakley Park and Glan-y-nant.
There are a large number of reservoirs in Wales reflecting the need for the supply of water for both industry and for consumption, both within the country itself and in neighbouring England. A number also provide hydroelectricity and many old reservoirs also provided motive power for industries, especially for the processing of minerals such as metal ores and slate.