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Elwy water levels

2 gauges from Pont Y Gwyddel River Station to St Asaph Spring Gardens River Station. None is above its typical high. 2 storm overflows upstream are discharging now. Gauges in Conwy, Denbighshire; levels are checked every 15 minutes.

2gauges
0above normal
2overflows upstream discharging

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Gauges

Monitoring stations, source to mouth

StationTownLevel nowStatusTrend
Pont Y Gwyddel River Station—0.80 m 32m agoWithin its typical range▽
St Asaph Spring Gardens River Station 17.6 km by river—9.59 mAOD 32m 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 Elwy 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 Elwy above St Asaph Spring Gardens River Station on the river map. Streams without a gauge are not counted here.

Where the Elwy goes

No gauge below St Asaph Spring Gardens River Station is known on the river map.

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.

Streams without a gauge

Named streams on the river map that flow into the Elwy 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 Aled (joins about 190 m above Pont Y Gwyddel River Station)
  • Afon Cledwen (joins about 13 km above Pont Y Gwyddel River Station)
  • Afon Meirchion (joins about 6.8 km above St Asaph Spring Gardens River Station)

Storm overflows upstream

7 storm overflows are traced upstream of St Asaph Spring Gardens River Station, the Elwy’s lowest gauge on the river map: on the Elwy itself, on its gauged tributaries, and on smaller streams that join above there.

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

Official figures for 2025, for the overflows traced upstream of St Asaph Spring Gardens River Station: 304 spills over 2,159 hours in total, across all 7.

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 Elwy includes the smaller streams that join it there.

Above Pont Y Gwyddel River Station, the Elwy’s highest gauge5 overflows · 2 discharging now
  • Rhostrehwfa Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into River Cledwen · 12.7 km by river above Pont Y Gwyddel River Station · 2025: 18 spills, 70 h
  • B5382 Llangernyw Storm Overflow Discharging now since
    Dwr Cymru Welsh Water · into River Elwy · 12.7 km by river above Pont Y Gwyddel River Station · 2025: 88 spills, 315 h
  • Llangernyw WwTW Overflow Discharging now since
    Dwr Cymru Welsh Water · into Elwy · 12.4 km by river above Pont Y Gwyddel River Station · 2025: 101 spills, 1,471 h
  • Llansannan Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into River Aled · 8.2 km by river above Pont Y Gwyddel River Station · 2025: 5 spills, 3.8 h
  • Llanfair Talhaiarn WwTW Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into River Elwy · 3.3 km by river above Pont Y Gwyddel River Station · 2025: 21 spills, 113 h
Between Pont Y Gwyddel River Station and St Asaph Spring Gardens River Station2 overflows
  • Henllan WwTW Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into Afon Meirchion · 8.8 km by river above St Asaph Spring Gardens River Station · 2025: 59 spills, 113 h
  • High Street St Asaph Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into River Clwyd · 720 m by river above St Asaph Spring Gardens River Station · 2025: 12 spills, 73 h

1 other overflow within 3 km of these gauges is placed below the Elwy’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.