The Afon Dulas, or North Dulas, is a river forming the border between Merionethshire/Gwynedd and Montgomeryshire/Powys in Wales. Another river called Afon Dulas joins the Dyfi from the south, upstream of its confluence with the North Dulas: locally this is referred to as the South Dulas.

The Dulas as it passes through Aberllefenni

Route of North DulasEdit

Afon Dulas rises from a source in the hills above Aberllefenni and passes through Corris, Esgairgeiliog and Pantperthog before joining the Afon Dyfi at Ffridd Gate near Machynlleth.[1]


The Dulas is recorded as an important land boundary in 1200, in a document written in 1428. This document describes the land owned by Einion ap Seisyllt, in the time of Llywelyn the Great, as "tota terra inter aquas de Dyfi et Delwas" (Latin, meaning: all the land between the rivers Dyfi and Dulas).[2]

Roads and railways in the Dulas valleyEdit

  • The A487 trunk road follows the valley from Ffridd Gate to Corris
  • The Roman road Sarn Helen probably followed the valley from Aberllefenni to Ffridd Gate
  • The Corris Railway ran through the valley from Aberllefenni to Ffridd Gate


South DulasEdit

It rises in Glaslyn, below the slopes of Foel Fadian, and passes the hamlet of Forge and Plas Dolguog before joining the Dyfi.

Close to its confluence with the Dyfi it is crossed by the Cambrian rail line on a bridge known as the Black Bridge. After the line had been repeatedly closed due to flooding after heavy rain, in 2021 it was announced that the bridge and its approaches were to be raised by a metre to try and alleviate the problem.[5] Work began on 15 May and was due to be completed by 28 June.


  • Afon Crewi at Felingerrig


  1. ^ W. T. Pratt; D. G. Woodhall; Malcolm Fletcher Howells; M. J. Leng (1995). Geology of the Country Around Cadair Idris. H.M. Stationery Office. ISBN 978-0-11-884509-0.
  2. ^ Owen, George (1892). "The Description of Pembrokshire". Cymmrodorion record series. London: Society of Cymmrodorion. 1: 221.
  3. ^ a b Cylchgrawn Cymdeithas Hanes a Chofnodion Sir Feirionydd. The Society. 1957.
  4. ^ Edwyn Jervoise; Society for the Protection of Ancient Buildings (London, England) (1936). The ancient bridges of Wales and western England. The Architectural press.
  5. ^ "Network Rail to improve flood delays by £3.6m bridge lift". Rail Technology Magazine. Retrieved 12 July 2021.

Coordinates: 52°36′00″N 3°50′30″W / 52.6001°N 3.8418°W / 52.6001; -3.8418