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Home › Rivers › Rhondda Fawr

Rhondda Fawr water levels

2 gauges from Tynewydd River Station to Gelli River Station. None is above its typical high. 1 storm overflow upstream is discharging now. Gauges in Rhondda Cynon Taf; levels are checked every 15 minutes.

2gauges
0above normal
1overflow upstream discharging

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Gauges

Monitoring stations, source to mouth

StationTownLevel nowStatusTrend
Tynewydd River Station—0.37 m 20m agoWithin its typical range▽
Gelli River Station 6.6 km by riverGelli0.43 m 20m agoWithin its typical range▽

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.

Contains OS data © Crown copyright and database rights 2026.

Gauged tributaries

Streams and rivers with a gauge whose water joins the Rhondda Fawr above one of its gauges, from the source down. The river map knows where gauges are, not every stream, so a tributary without a gauge is not listed here.

No gauged tributary joins the Rhondda Fawr above Gelli River Station on the river map. Streams without a gauge are not counted here.

Where the Rhondda Fawr goes

Below Gelli River Station, its water next reaches Trehafod River Station, a gauge on Rhondda, 11.6 km by river downstream.

Tributaries and where they join are traced on the river map (OS Open Rivers, edition 2026-04) and the Environment Agency’s links between its gauges. The map holds distances between gauges, not the junctions themselves, so a junction is placed between two gauges, and no further up than the tributary’s own lowest gauge. Contains OS data © Crown copyright and database rights 2026.

Storm overflows upstream

24 storm overflows are traced upstream of Gelli River Station, the Rhondda Fawr’s lowest gauge on the river map: on the Rhondda Fawr itself, on its gauged tributaries, and on smaller streams that join above there.

  • 1 reports discharging now
  • 22 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 Gelli River Station: 839 spills over 4,150 hours in total, across the 23 that have a figure. 1 has no 2025 figure.

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 Rhondda Fawr includes the smaller streams that join it there.

Above Tynewydd River Station, the Rhondda Fawr’s highest gauge3 overflows
Between Tynewydd River Station and Gelli River Station21 overflows · 1 discharging now

Near these gauges, connection not known

Within 3 km of one of the Rhondda Fawr’s gauges in a straight line, but the river map cannot say whether their water reaches it.

  • Rees Street Gelli Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into Rhondda River Fawr · 60 m from Gelli River Station in a straight line · too close to Gelli River Station to say which side · 2025: 39 spills, 45 h
  • Llewellyn Street Pentre Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into River Cynon · 1.4 km from Gelli River Station in a straight line · no mapped watercourse close enough to be sure · 2025: 6 spills, 2.3 h
  • Railway Terrace Clydach Vale Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into River Clydach · 2.2 km from Gelli River Station in a straight line · its recorded watercourse is not the one mapped beside it · 2025: 60 spills, 167 h
  • Davies Street Tonypandy Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into River Clydach · 2.6 km from Gelli River Station in a straight line · its recorded watercourse is not the one mapped beside it · 2025: 122 spills, 709 h
  • Park Road Cwmparc Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into Tributary Of Nant Cwmparc · 2.8 km from Gelli River Station in a straight line · several watercourses close by, nothing to choose between them · 2025: 3 spills, 0.8 h

11 other overflows within 3 km of these gauges are placed below the Rhondda Fawr’s lowest gauge or on another river, so not listed.

A status is the water company’s own monitor: it says whether an overflow is discharging, never how much or why, and a spill does not by itself explain a change in a river level. A status older than two hours is shown as unknown. Annual figures are the official returns: 12/24-hour spills for England and Wales, overflow events for Scotland (Scottish Water counts differently, so the two cannot be compared). “No data” means the monitor produced no usable data that year, not zero. Overflows are placed on OS Open Rivers (edition 2026-04), which leaves out many small channels: an overflow the map cannot place may still drain here. Contains OS data © Crown copyright and database rights 2026. Sewage in Britain’s rivers →

Live status: © Dŵr Cymru Welsh Water, from its Storm Overflow Map. Annual figures for Wales: Dŵr Cymru Welsh Water’s return to Natural Resources Wales, as compiled by The Rivers Trust, Open Government Licence.

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