Clywedog reservoir
Encyclopedia
The Clywedog reservoir is a reservoir
in the Welsh
county of Powys
, located off the B4518 road
near the town of Llanidloes
.
The reservoir was formed by damming the Afon Clywedog, a tributary of the River Severn
. Its concrete
buttress
dam
is the tallest concrete dam in the United Kingdom
, with a height of 72 metres and a length of 230 metres.
When at capacity the reservoir contains approximately 50,000 megalitres of water. A second, much smaller embankment dam
is located at Bwlch-y-gle to prevent overflow into the next valley
.
Construction of the dam commenced in 1963 after the passing of an Act of Parliament
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 2 months. The political extremist group Mudiad Amddiffyn Cymru
(MAC) was widely suspected of carrying out the bombing.
The reservoir
was opened in 1967 and till this day has been in continuous usage, 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 Water Limited with oversight and regulation from the Environment Agency
.
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.
In a TV ad for the Land Rover Defender, a Defender 90 is seen winching up the face of the dam under its own power.
Reservoir
A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...
in the Welsh
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
county of Powys
Powys
Powys is a local-government county and preserved county in Wales.-Geography:Powys covers the historic counties of Montgomeryshire and Radnorshire, most of Brecknockshire , and a small part of Denbighshire — an area of 5,179 km², making it the largest county in Wales by land area.It is...
, located off the B4518 road
B4518 road
The B4518 road is a road in Powys, central Wales, with a total length of . It begins at in Rhayader near the junction of the A470 road and the A44 road and leads eventually to the A470 again at Llanbrynmair at...
near the town of Llanidloes
Llanidloes
Llanidloes is a town along the A470 road and B4518 road in Powys, within the historic county boundaries of Montgomeryshire , Mid Wales.It is the first town on the River Severn...
.
The reservoir was formed by damming the Afon Clywedog, a tributary of the River Severn
River Severn
The River Severn is the longest river in Great Britain, at about , but the second longest on the British Isles, behind the River Shannon. It rises at an altitude of on Plynlimon, Ceredigion near Llanidloes, Powys, in the Cambrian Mountains of mid Wales...
. Its concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...
buttress
Buttress
A buttress is an architectural structure built against or projecting from a wall which serves to support or reinforce the wall...
dam
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
is the tallest concrete dam in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, with a height of 72 metres and a length of 230 metres.
Embankment dam
An embankment dam is a massive artificial water barrier. It is typically created by the emplacement and compaction of a complex semi-plastic mound of various compositions of soil, sand, clay and/or rock. It has a semi-permanent waterproof natural covering for its surface, and a dense, waterproof...
is located at Bwlch-y-gle to prevent overflow into the next valley
Valley
In geology, a valley or dale is a depression with predominant extent in one direction. A very deep river valley may be called a canyon or gorge.The terms U-shaped and V-shaped are descriptive terms of geography to characterize the form of valleys...
.
Construction of the dam commenced in 1963 after the passing of an Act of Parliament
Act of Parliament
An Act of Parliament is a statute enacted as primary legislation by a national or sub-national parliament. In the Republic of Ireland the term Act of the Oireachtas is used, and in the United States the term Act of Congress is used.In Commonwealth countries, the term is used both in a narrow...
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 2 months. The political extremist group Mudiad Amddiffyn Cymru
Mudiad Amddiffyn Cymru
Mudiad Amddiffyn Cymru , abbreviated as MAC, was a paramilitary Welsh nationalist organisation, which was responsible for a number of bombing incidents between 1963 and 1969....
(MAC) was widely suspected of carrying out the bombing.
The reservoir
Reservoir
A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...
was opened in 1967 and till this day has been in continuous usage, 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 Water Limited with oversight and regulation from the Environment Agency
Environment Agency
The Environment Agency is a British non-departmental public body of the Department for Environment, Food and Rural Affairs and an Assembly Government Sponsored Body of the Welsh Assembly Government that serves England and Wales.-Purpose:...
.
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.
In a TV ad for the Land Rover Defender, a Defender 90 is seen winching up the face of the dam under its own power.
External links
- Llyn Clywedog – Llanidloes web-site
- Welcome to Lyn Clywedog Reservoir – BirminghamUK archives