Afon Clywedog

This article is about the river in Powys. For other rivers of the same name, see Clywedog.

The Afon Clywedog is an upland headwater tributary of the River Severn in Powys, Wales. It is approximately 29 km (18 mi) 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 1,737 mm (68.4 in) and 1,836 mm (72.3 in).^[1]

Afon Clywedog
Clywedog at the base of Clywedog reservoir
Location
Country	United Kingdom, Wales
Region	Mid Wales
County	Powys
Settlement	Llanidloes, Staylittle
Physical characteristics
Source
• location	Plynlimon, Powys, Wales
• coordinates	52.5411°N 3.7168°W / 52.5411; -3.7168
Mouth
• location	River Severn, Llanidloes
• coordinates	52.4508°N 3.5406°W / 52.4508; -3.5406
Length	29.0 km (18.0 mi)
Discharge
• location	Llanidloes
• average	2.26 m3/s (80 cu ft/s)

River regulation

A large part of the upper catchment of the river is inundated by the Clywedog reservoir which stores water from the catchment, especially during the winter months, and releases it during periods of low flow to support the flow in the Severn so that drinking water may be abstracted downstream.^[2] The management rules also enable the reservoir to maintain the reservoir below maximum level during the winter so that there is capacity to absorb flood flows to reduce the impact of flooding further down the main river.^[3] The Afon Clywedog thus has a highly regulated flow with relatively high flow in dry conditions and reduced flow in wetter weather.

See also

• Bryntail lead mine
• List of rivers in Wales