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Seiont water levels

1 gauge, at Peblic Seiont 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.

1gauge
0above normal
2overflows upstream discharging

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Gauges

Monitoring stations, source to mouth

StationTownLevel nowStatusTrend
Peblic Seiont River Station—1.27 m 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 Seiont 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.

1 gauged tributary, 1 gauge

Where the Seiont goes

No gauge below Peblic Seiont 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.

Storm overflows upstream

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

  • 2 report discharging now
  • 6 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 Peblic Seiont River Station: 672 spills over 5,732 hours in total, across all 8.

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 Seiont includes the smaller streams that join it there.

Above Peblic Seiont River Station, the Seiont’s highest gauge8 overflows · 2 discharging now
  • Dôl Eilian Llanberis Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into Afon Hwch · 14.2 km by river above Peblic Seiont River Station · 2025: 45 spills, 105 h
  • Llanberis WwTW Storm Overflow Discharging now since bathing water
    Dwr Cymru Welsh Water · into Afon Y Bala · 13.4 km by river above Peblic Seiont River Station · 2025: 137 spills, 1,196 h
  • Llanberis Maes Padarn Storm Overflow Not discharging bathing water
    Dwr Cymru Welsh Water · into Goch Bach · 13.3 km by river above Peblic Seiont River Station · 2025: 50 spills, 266 h
  • Clwt-Y-Bont Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into Afon Caledffrwd · 11.3 km by river above Peblic Seiont River Station · 2025: 4 spills, 3.8 h
  • Stad Hafod Deiniolen Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into Afon Caledffrwd · 11.2 km by river above Peblic Seiont River Station · 2025: 129 spills, 630 h
  • Brynrefail Main Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into Afon Caledffrwd · 9.5 km by river above Peblic Seiont River Station · 2025: 52 spills, 296 h
  • Station Road Pontrhythallt Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into River Seiont · 7.3 km by river above Peblic Seiont River Station · 2025: 140 spills, 1,381 h
  • Llanrug WwTW Storm Overflow Discharging now since
    Dwr Cymru Welsh Water · into Afon Seiont · 5.8 km by river above Peblic Seiont River Station · 2025: 115 spills, 1,855 h

Near these gauges, connection not known

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

  • Crown Street Caernarfon Overflow Not discharging
    Dwr Cymru Welsh Water · into Menai Strait · 1.8 km from Peblic Seiont River Station in a straight line · discharges to the sea, an estuary or tidal water · 2025: 0 spills, 0 h
  • Castle Ditch Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into Afon Seiont · 1.9 km from Peblic Seiont River Station in a straight line · discharges into a tidal reach, where the water moves both ways · 2025: 0 spills, 0 h
  • Bank Quay Caernarfon Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into Menai Strait · 2.0 km from Peblic Seiont River Station in a straight line · discharges to the sea, an estuary or tidal water · 2025: 0 spills, 0 h
  • Balaclava Road Caernarfon Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into Menai Strait · 2.0 km from Peblic Seiont River Station in a straight line · discharges to the sea, an estuary or tidal water · 2025: 1 spill, 0.3 h
  • B4419 Caernarfon Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into Menai Strait · 2.0 km from Peblic Seiont River Station in a straight line · discharges to the sea, an estuary or tidal water · 2025: 67 spills, 96 h
  • Waterloo Port Road Storm Overflow Not discharging
    Dwr Cymru Welsh Water · into Menai Strait · 2.1 km from Peblic Seiont River Station in a straight line · discharges to the sea, an estuary or tidal water · 2025: 0 spills, 0 h

11 other overflows within 3 km of these gauges are placed below the Seiont’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.