Elan Valley Reservoirs

Elan Valley Reservoirs
Caban-coch Reservoir c. 1963.
Elan Valley Reservoirs
Location	Elan Valley in Powys, Wales
Coordinates	52°16′20″N 3°41′20″W / 52.27222°N 3.68889°W / 52.27222; -3.68889
Lake type	Reservoirs
Primary inflows	River Elan River Claerwen
Primary outflows	Elan aqueduct River Elan
Managing agency	Dŵr Cymru Welsh Water
Built	1893
First flooded	1896
Max. length	5.9 km (3.7 mi)[1]
Max. width	0.5 km (0.31 mi)[1]
Surface area	606 ha (1,500 acres)[1]
Average depth	41.5 m (136 ft)
Max. depth	56 m (184 ft)[1]
Water volume	99,499,000 m3 (80,665 acre⋅ft)[1]
Surface elevation	Between 250–368 m (820–1,207 ft)[1]
References	[1] Specifications, Elan Valley Visitor Centre

The Elan Valley Reservoirs (Welsh: Cronfeydd Cwm Elan) are a chain of man-made lakes created from damming the Elan and Claerwen rivers within the Elan Valley in Mid Wales. The reservoirs, which were built by the Birmingham Corporation Water Department, provide clean drinking water for Birmingham in the West Midlands of England. The five lakes are known as the Claerwen, Craig-goch, Pen-y-garreg, Garreg-ddu, and Caban-coch.^[2]

Water from the reservoirs is carried by gravity to Frankley Reservoir in Birmingham via the Elan aqueduct. Pumping is not required because the network drops 52 metres (171 ft) along its 73-mile (117 km) length from its source to Frankley. A gradient of 1:2,300 maintains a flow of less than 2 miles per hour (3.2 km/h); water takes one and a half to two days to reach Birmingham.^[3] The aqueduct, which was started in 1896 and opened in 1906, crosses several valleys and features numerous brick tunnels, pipelines, and valve houses.^[4]

Work to build the Elan Valley reservoirs was undertaken because the rapid growth of the industrial city of Birmingham in the late 19th century had led to a lack of available clean water. Numerous outbreaks of disease prompted Birmingham City Council to petition the British government which passed the Birmingham Corporation Water Act in 1892.^[5] It allowed the corporation to acquire by compulsory purchase all the land within the water catchment area of the Elan Valleys. Thousands of navvies (workers) and their families lived in the purpose-built Elan Village during the construction of the first four dams at the turn of the 20th century. In 1952, the Claerwen dam was opened by Elizabeth II in one of her first official engagements as monarch.

Drinking water from the Elan Valley is noted for being exceptionally soft, contrasting with water from local supplies in the West Midlands, not served by the Elan aqueduct, which are noted for hardness.^[6]

The reservoirs are now owned and managed by Dŵr Cymru Welsh Water. The water filtration works further down the valley is run by Severn Trent Water.