Llwyn-onn Reservoir
| Llwyn-on Reservoir | |
|---|---|
 | |
| Location | South Wales |
| Coordinates | 51°47′50″N 3°26′27″W / 51.79722°N 3.44083°W |
| Type | reservoir |
| Primary inflows | Taf Fawr, Nant Gwinau, Nant Car, Garwnant |
| Primary outflows | Taf Fawr |
| Basin countries | United Kingdom |
Llwyn-on Reservoir (or Llwyn Onn Reservoir) is the largest and southernmost of the three reservoirs in the Taf Fawr valley in South Wales. The valley was dammed to provide Cardiff with a clean water supply. The scheme first proposed in the late 19th century but not completed until the 1920s.
The reservoir, which is owned and managed by Welsh Water, is located within the Brecon Beacons National Park with its eastern half in the Merthyr Tydfil unitary authority area and the western half in Rhondda Cynon Taf. The village of Llwyn-On is nearby. The A470 trunk road runs along its eastern shoreline.
History
In 1884, the Cardiff Corporation was granted a private Act of Parliament to dam the River Taf Fawr a 4 mi (6.4 km) upstream from Merthyr Tydfil to create a reservoir with a capacity of 670 million imperial gallons (3.0 Gl). In 1909, a new Act was passed that doubled the permitted size to 1,260 million imperial gallons (5.7 Gl).[1]
Work to build the earthen dam started in January 1911. The contractor was Louis P Nott of Llanelly and Bristol. However, construction ceased in 1915 because of the First World War. It restarted in 1919. The navvies original work huts were built next to the dam site with their accommodation on the other side of the main road. But when work restarted after the war, the bunkhouses were demolished and replaced by new ones next to the workshops. A railway branch was built from Cefn-coed-y-cymmer in 1911 to the dam's worksite. The line was removed in 1928 with the dam's completion.[1]
After the 28 m (92 ft) dam was completed in June 1926, the reservoir was allowed to fill up before being officially opened the following year in May 1927. It is fed by the Afon Taf Fawr, and the smaller tributaries of the Nant Gwinau, Nant Car and Garwnant.[1]
Recreation
To the east of the reservoir is the 462 metres (1,516 ft) mountain of Garn Ddu, and to the west is the 485 metres (1,591 ft) mountain of Cadair Fawr. There are a variety of guided walks and waymarked paths. Environmental sculptures can be found on the Wern and Willow walks. The Taff Trail and the Navvies Line paths link Cefn-coed-y-cymmer to Brecon. There is one bird hide.
In 2020, Welsh Water blocked off lay-bys around the Llwyn Onn reservoir because of persistent complaints about them being used for antisocial behaviour such as dogging.[2]
References
- ^ a b c "LLWYN-ON RESERVOIR, TAFF FAWR RESERVOIRS, CARDIFF WATERWORKS". www.coflein.gov.uk. Retrieved 1 June 2020.
- ^ "Dogging lay-bys blocked off at Llwyn Onn reservoir". BBC News. 3 August 2017. Retrieved 6 February 2020.
External links
- "Welsh Water Recreation Guide" (PDF). Archived from the original (PDF) on 2006-05-07. (409 KiB)
- "Cardiff Water Supply". Engineering Timelines.
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