Afon Merddwr is a river in the south of the county of

Conwy Conwy (, ), previously known in English as Conway, is a walled market town, community and the administrative centre of Conwy County Borough in North Wales. The walled town and castle stand on the west bank of the River Conwy, facing Deganwy on ...

, Wales. It is a tributary of the

River Conwy , name_etymology = , image = Boats in River Conwy.jpg , image_size = 300 , image_caption = Boats in the river estuary at Conwy , map = , map_size = , map_caption = , push ...

and joins it near

Pentrefoelas Pentrefoelas is a village and community in Conwy County Borough, Wales. The village lies on the A5 road between Betws-y-Coed to the west and Cerrigydrudion to the east. The Afon Merddwr river, a tributary of the River Conwy, flows through it. Th ...

. It is about 10 km long. "Merddwr" is Welsh for '' backwater'' or ''

stagnant water Water stagnation occurs when water stops flowing. Stagnant water can be a major environmental hazard. Dangers Malaria and dengue are among the main dangers of stagnant water, which can become a breeding ground for the mosquitoes that transmi ...

'', suggesting that it was named for its current or water quality. Y Merddwr - geograph

Course of the river

The source of the river is on the southern slopes of

Mwdwl-eithin Mwdwl-eithin () is the highest point on the Denbigh Moors (Welsh: Mynydd Hiraethog) of North Wales. This gently rising mountain lies about east of Betws-y-Coed. On its summit is a trig point and a ruined building which still provides shelter ag ...

(532 m), the highest hill in

Mynydd Hiraethog Denbigh Moors ( Welsh: Mynydd Hiraethog) is an upland region in Conwy and Denbighshire in north-east Wales, between Snowdonia and the Clwydian Range. It includes the large reservoirs Llyn Brenig and Llyn Alwen, and the Clocaenog Forest, which h ...

(the Denbigh Moors). Its name for the first part of its course is Afon Llaethog ("Milky River"). It flows south before turning west near the small village of Glasfryn. Several streams flow down from the hills into the river as it flows through

wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...

and

marshes A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found at ...

to its confluence near Rhydlydan with the Afon Nug, a small stream that flows from the hills above Pentrefoelas. The marshes are a

Site of Special Scientific Interest A Site of Special Scientific Interest (SSSI) in Great Britain or an Area of Special Scientific Interest (ASSI) in the Isle of Man and Northern Ireland is a conservation designation denoting a protected area in the United Kingdom and Isle of ...

known as Corsydd Nug a Merddwr ("Nug and Merddwr Marshes"). The river flows beside the

A5 road A5 Road may refer to: ;Africa *A5 highway (Nigeria), a road connecting Lagos and Ibadan * A5 road (Zimbabwe), a road connecting Harare and Francistown ;Americas * Quebec Autoroute 5, a road in Quebec, Canada * County Route A5 (California) or Bowm ...

, under a bridge for the B5113 near Pentrefoelas, and on for another 2 km to the River Conwy north of

Ysbyty Ifan Ysbyty Ifan (often formerly anglicised as Yspytty Ifan) is a small, historic village and community in the Conwy County Borough of Wales. The population in 2011 was 196 in 76 households (29 household spaces had no usual residents), over 79% of t ...

References

{{Authority control Merddwr Merddwr