Coedty Reservoir is a

reservoir A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation. Reservoirs are created by controlling a watercourse that drains an existing body of wa ...

Snowdonia Snowdonia, or Eryri (), is a mountainous region and National parks of the United Kingdom, national park in North Wales. It contains all 15 mountains in Wales Welsh 3000s, over 3000 feet high, including the country's highest, Snowdon (), which i ...

North Wales North Wales ( ) is a Regions of Wales, region of Wales, encompassing its northernmost areas. It borders mid Wales to the south, England to the east, and the Irish Sea to the north and west. The area is highly mountainous and rural, with Snowdon ...

. It is fed by the waters of Afon Porth-llwyd which flows from

Llyn Eigiau Llyn Eigiau is a lake on the edge of the Carneddau range of mountains in Snowdonia, Conwy, Wales. The name ''Eigiau'' is thought to refer to the shoals of fish which once lived here. Early maps refer to it as ''Llynyga''. It is thought that ...

. The reservoir lies at a height of , and measures some in size. It contains brown trout. The original dam was built in 1924 to provide hydro-electric power to the aluminium smelting works in Dolgarrog. In 1925, the Eigiau dam broke, and the flood of water from that also burst Coedty dam. The resultant flood caused the loss of 16 lives in Dolgarrog. The dam was rebuilt in 1926, and altered again in 1956. Water from the reservoir, which has a catchment area of around 27 square kilometres, is carried via a 3 km large metal pipe down to the hydro-electric power-station in Dolgarrog.RWE Innergy - Dolgarrog site
Coedty dam is a balance tip dam; water flows from it automatically when it reaches high levels. This excess water flows into a spectacular gorge used by outdoor pursuit groups. Gorge walking here, however, can be dangerous because of the sudden releases of water from the reservoir which can occur. The eastern side of the lake is skirted by the trackbed of the former Eigiau Tramway, created to aid the construction and maintenance of Llyn Eigiau dam. Nearby the Cowlyd Tramway branched off, built to aid the construction of the dam at Llyn Cowlyd.

References

{{authority control Caerhun Dolgarrog Reservoirs in Conwy County Borough Reservoirs in Snowdonia Dam failures in Europe 1925 disasters in the United Kingdom de:Eigiau und Coedty