5 gauges from Rhyd Y Mwyn DL River Station to Rossett River Station. None of the 4 that can be compared with a typical high is above it. Gauges in Flintshire, Wrexham; levels are checked every 15 minutes.
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.
Streams and rivers with a gauge whose water joins the Alun 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 Alun above Rossett River Station on the river map. Streams without a gauge are not counted here.
Named streams on the river map that flow into the Alun 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.
30 storm overflows are traced upstream of Rossett River Station, the Alun’s lowest gauge on the river map: on the Alun itself, on its gauged tributaries, and on smaller streams that join above there.
0 report discharging now
28 not discharging
2 offline or silent: 2 monitor offline, 0 status unknown, 0 no live feed
Official figures for 2025, for the overflows traced upstream of Rossett River Station: 385 spills over 1,533 hours in total, across the 28 that have a figure. 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 Alun includes the smaller streams that join it there.
Above Rhyd Y Mwyn DL River Station, the Alun’s highest gauge3 overflows
Off Church Terrace Llandegla Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 20.0 km by river above Rhyd Y Mwyn DL River Station · 2025: 5 spills, 14 h
Llanarmon Yn Ial WwTW OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 15.4 km by river above Rhyd Y Mwyn DL River Station · 2025: 59 spills, 178 h
Llanferres Storm OverflowNot discharging Dwr Cymru Welsh Water · into Tributary Of Afon Alun · 9.2 km by river above Rhyd Y Mwyn DL River Station · 2025: 6 spills, 59 h
Between Rhyd Y Mwyn DL River Station and Mold Leadmill Bridge River Station1 overflow
Maes Y Dre Mold Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 360 m by river above Mold Leadmill Bridge River Station · 2025: 4 spills, 2.0 h
Between Mold Leadmill Bridge River Station and Pont Blyddyn River Station9 overflows
Bryn Awelon Mold Storm OverflowNot discharging Dwr Cymru Welsh Water · into Tributary Of Black Brook · 6.8 km by river above Pont Blyddyn River Station · 2025: 12 spills, 68 h
Milford Street And Bro Alun Mold OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 6.8 km by river above Pont Blyddyn River Station · 2025: 18 spills, 14 h
Bryn Coch Lane Mold Storm OverflowNot discharging Dwr Cymru Welsh Water · into Unnamed Tributary Of Afon Alyn · 6.4 km by river above Pont Blyddyn River Station · 2025: 0 spills, 0 h
Victoria Terrace Mold Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 6.3 km by river above Pont Blyddyn River Station · 2025: 4 spills, 3.3 h
Fford Argoed Fields Storm OverflowMonitor offline Dwr Cymru Welsh Water · into River Alyn · 6.0 km by river above Pont Blyddyn River Station · 2025: 3 spills, 0.8 h
Gas Lane Mold Storm OverflowNot discharging Dwr Cymru Welsh Water · into Unnamed Tributary Of Afon Alyn · 5.7 km by river above Pont Blyddyn River Station · 2025: 10 spills, 5.0 h
Bromfield Lane Mold Storm OverflowNot discharging Dwr Cymru Welsh Water · into Tributary Of Afon Alyn · 5.2 km by river above Pont Blyddyn River Station · 2025: 17 spills, 14 h
Mold WwTW Storm OverflowNot discharging Dwr Cymru Welsh Water · into Tributary Of Afon Alyn · 5.0 km by river above Pont Blyddyn River Station · 2025: 56 spills, 359 h
Pontblyddyn Dingle Road Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 320 m by river above Pont Blyddyn River Station · 2025: 3 spills, 27 h
Between Pont Blyddyn River Station and Pont Y Capel River Station15 overflows
Pontybodkin Main Storm OverflowNot discharging Dwr Cymru Welsh Water · into Nant Byr · 14.2 km by river above Pont Y Capel River Station · 2025: 1 spill, 0.8 h
Buckley Ty Gwyn Storm OverflowNot discharging Dwr Cymru Welsh Water · into Black Brook · 14.1 km by river above Pont Y Capel River Station · 2025: 18 spills, 127 h
Pont Y Bodkin Lower Storm OverflowMonitor offline Dwr Cymru Welsh Water · into Byr Brook · 14.0 km by river above Pont Y Capel River Station · 2025: 17 spills, 272 h
Ffrith Storm OverflowNot discharging Dwr Cymru Welsh Water · into Afon Cegidog · 8.8 km by river above Pont Y Capel River Station · 2025: 0 spills, 0 h
Hope WwTW Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 7.9 km by river above Pont Y Capel River Station · 2025: 0 spills, 0 h
Sarn Lane Hope Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 7.8 km by river above Pont Y Capel River Station · 2025: 3 spills, 0.8 h
Hope Cymau Storm OverflowNot discharging Dwr Cymru Welsh Water · into Afon Cegidog · 7.6 km by river above Pont Y Capel River Station · 2025: 8 spills, 6.3 h
Hope Street Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 7.1 km by river above Pont Y Capel River Station · 2025: 1 spill, 0.3 h
Rhyddyn Hill Caergwrle Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 6.6 km by river above Pont Y Capel River Station · 2025: 13 spills, 36 h
East Of Railway Cefn Y Bedd Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 5.7 km by river above Pont Y Capel River Station · 2025: 34 spills, 36 h
Cefn Y Bedd Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 4.5 km by river above Pont Y Capel River Station · 2025: 2 spills, 1.8 h
Cherry Tree Road Bradley Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 2.2 km by river above Pont Y Capel River Station · 2025: 21 spills, 39 h
Pandy OverflowNot discharging Dwr Cymru Welsh Water · into River Alun · 770 m by river above Pont Y Capel River Station · no official annual figure
Pandy Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 770 m by river above Pont Y Capel River Station · no official annual figure
Between Pont Y Capel River Station and Rossett River Station2 overflows
Gresford WwTW Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 2.9 km by river above Rossett River Station · 2025: 36 spills, 217 h
Rossett Level Crossing Storm OverflowNot discharging Dwr Cymru Welsh Water · into River Alyn · 300 m by river above Rossett River Station · 2025: 22 spills, 14 h
Near these gauges, connection not known
Within 3 km of one of the Alun’s gauges in a straight line, but the river map cannot say whether their water reaches it.
Bronallt Leeswood Storm OveerflowNot discharging Dwr Cymru Welsh Water · into Unnamed Tributary Of Afon Alyn · 620 m from Pont Blyddyn River Station in a straight line · its watercourse is not on the river map · 2025: 40 spills, 404 h
Leeswood Bethania Storm OverflowNot discharging Dwr Cymru Welsh Water · into Nant Brook · 810 m from Pont Blyddyn River Station in a straight line · no mapped watercourse close enough to be sure · 2025: 3 spills, 7.3 h
Gladstone Street Glanrafon Road Storm OverflowNot discharging Dwr Cymru Welsh Water · into Unnamed Tributary Of The River Alyn · 1.0 km from Mold Leadmill Bridge River Station in a straight line · several watercourses close by, nothing to choose between them · 2025: 24 spills, 22 h
Wrexham Acton Storm OverflowNot discharging Dwr Cymru Welsh Water · into Pond Adjacent · 1.1 km from Pont Y Capel River Station in a straight line · discharges to a loch, lake or reservoir · 2025: 3 spills, 1.3 h
A549 Mold Storm OverflowNot discharging Dwr Cymru Welsh Water · into Tributary Of The Afon Alyn · 1.2 km from Mold Leadmill Bridge River Station in a straight line · no mapped watercourse close enough to be sure · 2025: 39 spills, 128 h
Pen Y Llyn Gwersyllt Storm OverflowNot discharging Dwr Cymru Welsh Water · into Gwersyllt Fishpond · 1.3 km from Pont Y Capel River Station in a straight line · its watercourse is not on the river map · 2025: 14 spills, 32 h
Chambers Lane Mercia Drive Junction Storm OverflowNot discharging Dwr Cymru Welsh Water · into Tributary Of Afon Alun · 1.5 km from Mold Leadmill Bridge River Station in a straight line · its watercourse is not on the river map · 2025: 36 spills, 76 h
Llay Singrett Storm OverflowNot discharging Dwr Cymru Welsh Water · into Singret Brook · 1.7 km from Pont Y Capel River Station in a straight line · no mapped watercourse close enough to be sure · 2025: 47 spills, 127 h
Chambers Lane Mercia Drive Junction Storm Overflow No2Not discharging Dwr Cymru Welsh Water · into Tributary Of Afon Alyn · 1.7 km from Mold Leadmill Bridge River Station in a straight line · its watercourse is not on the river map · 2025: 48 spills, 102 h
Wats Duke Avenue Storm OverflowNot discharging Dwr Cymru Welsh Water · into Tributary Of Afon Alyn · 1.9 km from Mold Leadmill Bridge River Station in a straight line · its watercourse is not on the river map · 2025: 23 spills, 119 h
Mercia Drive Mold Storm OverflowNot discharging Dwr Cymru Welsh Water · into Surface Water Sewer · 2.0 km from Mold Leadmill Bridge River Station in a straight line · its watercourse is not on the river map · 2025: 34 spills, 81 h
Llay Road Llay Storm OverflowNot discharging Dwr Cymru Welsh Water · into Tributary Of Afon Alyn · 2.2 km from Pont Y Capel River Station in a straight line · its watercourse is not on the river map · 2025: 15 spills, 43 h
Padeswood Road Buckley Storm OverflowNot discharging Dwr Cymru Welsh Water · into Foundry Drain · 2.3 km from Pont Blyddyn River Station in a straight line · its watercourse is not on the river map · 2025: 47 spills, 387 h
West View Penyffordd Storm OverflowNot discharging Dwr Cymru Welsh Water · into Black Brook · 2.4 km from Pont Blyddyn River Station in a straight line · its watercourse is not on the river map · 2025: 0 spills, 0 h
Rhosnesni Lane Wrexham OverflowNot discharging Dwr Cymru Welsh Water · into River Gwenfro · 2.7 km from Pont Y Capel River Station in a straight line · its watercourse is not on the river map · 2025: 7 spills, 2.0 h
4 other overflows within 3 km of these gauges are placed below the Alun’s lowest gauge or on another river, so not listed.