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Home › Rivers › Sirhowy

Sirhowy water levels

2 gauges from Nant Y Bwch River Station to Ynysddu River Station. None is above its typical high. Gauges in Blaenau Gwent, Caerphilly; levels are checked every 15 minutes.

2gauges
0above normal

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Gauges

Monitoring stations, source to mouth

StationTownLevel nowStatusTrend
Nant Y Bwch River Station—0.40 m 31m agoWithin its typical range▼
Ynysddu River Station 23.3 km by riverYnysddu0.57 m 16m 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 Sirhowy 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 Sirhowy above Ynysddu River Station on the river map. Streams without a gauge are not counted here.

Where the Sirhowy goes

Below Ynysddu River Station, its water next reaches Risca River Station, a gauge on Ebbw, 7.8 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

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

  • 0 report discharging now
  • 29 not discharging
  • 3 offline or silent: 3 monitor offline, 0 status unknown, 0 no live feed

Official figures for 2025, for the overflows traced upstream of Ynysddu River Station: 1,430 spills over 5,099 hours in total, across the 30 that have a figure. 2 had no usable monitor data that year.

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 Sirhowy includes the smaller streams that join it there. Every overflow traced is listed here, each stretch in full. Back to the short lists →

Between Nant Y Bwch River Station and Ynysddu River Station32 overflows

Near these gauges, connection not known

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

  • Ladies Row Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into Sirhowy River · 1.9 km from Nant Y Bwch River Station in a straight line · no mapped watercourse close enough to be sure · 2025: 10 spills, 9.3 h

5 other overflows within 3 km of these gauges are placed below the Sirhowy’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.

Wave tracker for this river → Blaenau Gwent rivers → Caerphilly rivers → All UK rivers