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4 gauges from Hirwaun River Station to Abercynon River Station. None is above its typical high. 3 storm overflows upstream are discharging now. Gauges in Rhondda Cynon Taf; levels are checked every 15 minutes.
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| Station | Level now | Status |
|---|---|---|
| Hirwaun River Station | 0.37 m 17m ago | Within its typical range |
| Aberdare River Station 6.3 km by river | 0.39 m 32m ago | Within its typical range |
| Mountain Ash River Station 6.2 km by river | 1.04 m 32m ago | Within its typical range |
| Abercynon River Station 5.3 km by river | 0.69 m 32m ago | Within 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.
Streams and rivers with a gauge whose water joins the Cynon above one of its gauges, from the source down. Named streams without a gauge that have a page here are listed at the end.
No gauged tributary joins the Cynon above Abercynon River Station on the river map. Streams without a gauge are not counted here.
Below Abercynon River Station, its water next reaches Pontypridd River Station, a gauge on Taff, 7.9 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.
45 storm overflows are traced upstream of Abercynon River Station, the Cynon’s lowest gauge on the river map: on the Cynon itself, on its gauged tributaries, and on smaller streams that join above there.
Official figures for 2025, for the overflows traced upstream of Abercynon River Station: 1,765 spills over 9,154 hours in total, across the 42 that have a figure. 1 had no usable monitor data that year; 2 have 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 Cynon includes the smaller streams that join it there. Where a stretch or a tributary has more than 4, the 3 discharging now or nearest its gauge are listed, the rest are counted, and every one is in that gauge’s “Upstream of here” list. Show every overflow in every stretch →
and 8 more: show all 11 overflows on this stretch → All above Aberdare River Station, nearest first →
and 16 more: show all 19 overflows on this stretch → All above Mountain Ash River Station, nearest first →
and 9 more: show all 12 overflows on this stretch → All above Abercynon River Station, nearest first →
Within 3 km of one of the Cynon’s gauges in a straight line, but the river map cannot say whether their water reaches it.
21 more near these gauges whose connection is not known.
14 other overflows within 3 km of these gauges are placed below the Cynon’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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