1 gauge, at Afon Dyfi River Station. It is not above its typical high. 2 storm overflows upstream are discharging now. Gauges in Gwynedd; levels are checked every 15 minutes.
Stations are listed from source to mouth as the water flows, traced on the river map (OS Open Rivers) and the Environment Agency’s own links between its gauges. A distance “by river” is along the river, and is shown only where the map traces the path.
Streams and rivers with a gauge whose water joins the Dyfi above one of its gauges, from the source down. Named streams without a gauge that have a page here are listed at the end.
Named streams on the river map that flow into the Dyfi and have no gauge of their own. Each has a page with what is known about it: the next gauge downstream, and any storm overflows or water-sampling points placed on it.
Afon Angell (joins about 16 km above Afon Dyfi River Station)
Afon Dulas (joins about 860 m above Afon Dyfi River Station)
Afon Twymyn (joins about 9.6 km above Afon Dyfi River Station)
Storm overflows upstream
6 storm overflows are traced upstream of Afon Dyfi River Station, the Dyfi’s lowest gauge on the river map: on the Dyfi itself, on its gauged tributaries, and on smaller streams that join above there.
2 report discharging now
3 not discharging
1 offline or silent: 1 monitor offline, 0 status unknown, 0 no live feed
Official figures for 2025, for the overflows traced upstream of Afon Dyfi River Station: 293 spills over 5,344 hours in total, across all 6.
Each overflow is listed in the stretch above the first gauge its water reaches, from the source down, as on the Gauges tab. A stretch of the Dyfi includes the smaller streams that join it there.
Above Afon Dyfi River Station, the Dyfi’s highest gauge6 overflows · 2 discharging now
Bontdolgadfan Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Twymyn · 22.8 km by river above Afon Dyfi River Station · 2025: 0 spills, 0 h
Llanbrynmair Tafolwern WwTW Storm OverflowDischarging now since Dwr Cymru Welsh Water · into Afon Iaen · 19.2 km by river above Afon Dyfi River Station · 2025: 95 spills, 1,856 h
Commins Coch Storm OverflowDischarging now since Dwr Cymru Welsh Water · into River Twymyn · 13.5 km by river above Afon Dyfi River Station · 2025: 120 spills, 2,676 h
Minffordd Street Corris Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Deri · 8.7 km by river above Afon Dyfi River Station · 2025: 5 spills, 3.8 h
Corris WwTW Storm OverflowMonitor offline Dwr Cymru Welsh Water · into Afon Dulas · 8.4 km by river above Afon Dyfi River Station · 2025: 72 spills, 801 h
Near these gauges, connection not known
Within 3 km of one of the Dyfi’s gauges in a straight line, but the river map cannot say whether their water reaches it.
Heol Y Doll Machynlleth Storm OverflowNot discharging Dwr Cymru Welsh Water · into Garsiwn Ditch · 790 m from Afon Dyfi River Station in a straight line · no mapped watercourse close enough to be sure · 2025: 62 spills, 86 h
Machynlleth WwTW Inlet Storm OverflowNot discharging Dwr Cymru Welsh Water · into Garsiwn Ditch · 1.0 km from Afon Dyfi River Station in a straight line · no mapped watercourse close enough to be sure · 2024: 0 spills, 0 h
Garsiwn Ditch Storm OverflowNot discharging Dwr Cymru Welsh Water · into Garsiwn Ditch · 1.1 km from Afon Dyfi River Station in a straight line · no mapped watercourse close enough to be sure · 2025: 14 spills, 8.3 h
Machynlleth WwTW Settled Storm OverflowNot discharging Dwr Cymru Welsh Water · into Garsiwn Ffos · 1.1 km from Afon Dyfi River Station in a straight line · no mapped watercourse close enough to be sure · 2025: 65 spills, 461 h
Machynlleth WwTW Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Dyfi · 1.1 km from Afon Dyfi River Station in a straight line · no mapped watercourse close enough to be sure · 2025: 55 spills, 410 h
Machynlleth Popular Terrace Storm OverflowNot discharging Dwr Cymru Welsh Water · into Unnamed Ditch · 1.2 km from Afon Dyfi River Station in a straight line · no mapped watercourse close enough to be sure · 2025: 21 spills, 7.8 h