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We get information about overflowing CSOs since January 2025. Here is a chart of the last three months of data for Clwyd North, here you can see overflows in red, the darker the red, the more the CSO overflowed that day.
Each CSO has a row, the most recent data is on the right hand side.
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Donate Now| Company | Site Name | Receiving Waterway | Overflow Days | Total Duration (hours) | Total Duration (days) |
|---|---|---|---|---|---|
| Dwr Cymru Welsh Water | Ganol WwTW Storm Overflow | Coastal waters - Penrhyn Bay | 81 | 575 h 23m | 23.96 |
| Dwr Cymru Welsh Water | Pensarn Storm Overflow | Coastal Waters - Pensarn Beach | 50 | 398 h 45m | 16.58 |
| Dwr Cymru Welsh Water | Denbigh WwTW Storm Overflow | River Clwyd | 26 | 316 h 30m | 13.17 |
| Dwr Cymru Welsh Water | Church Road Rhos-on-Sea Storm Overflow | Coastal Waters - Penrhyn Bay | 39 | 190 h 17m | 7.92 |
| Dwr Cymru Welsh Water | Kinmel Bay WwTW Storm Overflow | Coastal Water - Liverpool Bay | 23 | 176 h 30m | 7.33 |
| Dwr Cymru Welsh Water | Llawr Pentre Abergele Road Storm Overflow | Nant Y Ffynnon | 13 | 102 h 50m | 4.25 |
| Dwr Cymru Welsh Water | Bodelwyddan Storm Tanks Storm Overflow | Bodelwyddan Drain | 18 | 97 h 45m | 4.04 |
| Dwr Cymru Welsh Water | Henllan WwTW Storm Overflow | Afon Meirchion | 47 | 74 h 30m | 3.08 |
| Dwr Cymru Welsh Water | East of Station Road Colwyn Bay Storm Overflow | Colwyn Bay | 9 | 68 h 20m | 2.83 |
| Dwr Cymru Welsh Water | Towyn Storm Overflow | Coastal Waters | 11 | 59 h 15m | 2.46 |
| Dwr Cymru Welsh Water | Llandulas Storm Overflow | Coastal Water - Liverpool Bay | 13 | 58 h 15m | 2.42 |
| Dwr Cymru Welsh Water | Denbigh Ruthin Road Storm Overflow | Afon Ystrad | 20 | 51 h 30m | 2.12 |
| Dwr Cymru Welsh Water | Plas Yn Green Storm Overflow | Tributary of the Clwyd | 9 | 48 h 15m | 2 |
| Dwr Cymru Welsh Water | Beach Road Old Colwyn Storm Overflow | Coastal waters - Colwyn Bay | 14 | 46 h 30m | 1.92 |
| Dwr Cymru Welsh Water | Rhuddlan WwTW Storm Overflow | River Clwyd | 14 | 45 h 22m | 1.88 |
| Dwr Cymru Welsh Water | High Street St Asaph Storm Overflow | River Clwyd | 10 | 44 h 30m | 1.83 |
| Dwr Cymru Welsh Water | Marine Lake Storm Overflow | Coastal Waters - Irish Sea | 6 | 44 h 30m | 1.83 |
| Dwr Cymru Welsh Water | Towyn Road Storm Overflow | Ffynnon Y Ddol | 6 | 36 h 44m | 1.5 |
| Dwr Cymru Welsh Water | Beacons Road and Grove Road Denbigh Storm Overflow | Henllan Brook | 6 | 36 h 26m | 1.5 |
| Dwr Cymru Welsh Water | Roe Parc St Asaph Storm Overflow | River Elwy | 7 | 30 h 14m | 1.25 |
| Dwr Cymru Welsh Water | Rhyl Coast Road Storm Overflow | The Rhyl Cut | 5 | 29 h 43m | 1.21 |
| Dwr Cymru Welsh Water | Panton Hall Denbigh Storm Overflow | Henllan Brook | 24 | 27 h 30m | 1.12 |
| Dwr Cymru Welsh Water | Trefnant Storm Overflow | Unnamed Drain leading to Afon Clwyd | 4 | 25 h 31m | 1.04 |
| Dwr Cymru Welsh Water | Rhuddlan Storm Overflow | Tidal Estuary of Afon Clwyd | 5 | 20 h | 0.83 |
| Dwr Cymru Welsh Water | Maes Y Llan Storm Overflow | Ffynnon Y Ddol | 3 | 17 h 15m | 0.71 |
| Dwr Cymru Welsh Water | Dalar Wen Denbigh Storm Overflow | Henllan Brook | 14 | 12 h 2m | 0.5 |
| Dwr Cymru Welsh Water | Min Y Don Woodland Storm Overflow | Unnamed Tributary of Colwyn Bay | 19 | 11 h 41m | 0.46 |
| Dwr Cymru Welsh Water | Westbourne Grove Storm Overflow | Coastal Waters - Irish Sea | 4 | 6 h 58m | 0.25 |
| Dwr Cymru Welsh Water | Tan Y Foel Rhyd Y Foel Storm Overflow | Afon Dulas | 5 | 5 h 45m | 0.21 |
| Dwr Cymru Welsh Water | Berth Glyd Storm Overflow | Tributary of Afon Gele | 5 | 4 h 57m | 0.17 |
| Dwr Cymru Welsh Water | Clifton Park Road Rhyl Storm Overflow 1 | Rhyl Cut | 2 | 3 h 41m | 0.12 |
| Dwr Cymru Welsh Water | Clifton Park Road Rhyl Storm Overflow 2 | Rhyl Cut | 1 | 3 h 30m | 0.12 |
| Dwr Cymru Welsh Water | Ffordd Ffynnon Rhuddlan Storm Overflow | Afon Ffyddion | 1 | 2 h 29m | 0.08 |
| Dwr Cymru Welsh Water | Marine Road Colwyn Bay Storm Overflow | Colwyn Bay | 5 | 1 h 30m | 0.04 |
| Dwr Cymru Welsh Water | Abbey Road Denbigh Storm Overflow | Henllan Brook | 1 | 0 h 30m | 0 |
| Dwr Cymru Welsh Water | Foryd Road and Dinas Avenue Kimmel Bay Overflow | Kinmel Bay Drain | 1 | 0 h 29m | 0 |
| Dwr Cymru Welsh Water | Brondyffyn Storm Overflow | Nant Padrig | 1 | 0 h 29m | 0 |
| Dwr Cymru Welsh Water | Maes Mathonwy Denbigh Storm Overflow | River Dee | 1 | 0 h 15m | 0 |
| Dwr Cymru Welsh Water | Abergele Road Storm Overflow | Colwyn Bay | 0 | 0 h | 0 |
EDM (Event Duration Monitoring) data and Consented Discharges to Controlled Waters with Conditions from Environment Agency & Data Map Wales, and Scottish Water
Experimental derived data from Thames Water API, Some data may be missing or inaccurate. Live sewage data from Stream Water API
Uses Environment Agency rainfall data from the real-time data API (Beta) - Rainfall data is delayed by up to two days.
This website is intended to provide an accurate representation of the Environment Agency data. The data is hard to use, and thus some errors may have been made. If you find something that is incorrect, please raise an issue at the GitHub issues page and we'll endeavour to fix it quickly.
This project is not associated, approved or endorsed by any of the companies whose logos you see here.
Get in touch if you have queries or want to discuss our data.
press [at] top-of-the-poops.org