Trerhyngyll Overflow
Storm overflow run by Dwr Cymru Welsh Water, discharging into Unnamed Tributary Of The River Thaw.
"Not discharging" means the company's monitor reports no discharge right now — not that the water is clean. The feed publishes status only; no discharge volume is measured.
Year by year
The Environment Agency's official annual returns, counted the EA's way (12/24-hour spills). 2026 is our own running count, the same way, from the live feed since 23 September (when we began keeping every discharge it reports) — so it can only be lower than the full year. The official figure is published next spring.
A spill is the EA's 12/24-hour count: the first 12 hours of a discharge count as one, each further 24 hours with discharge as one more. "Monitor" is the share of that year the monitor was working, so a 0 beside a working monitor is a real zero; "no data" means the monitor produced no usable data that year — not zero. Years before 2024 are matched to this site by name and location, because the EA's site IDs changed that year; a monitor figure beside one of them means the outlet's permit confirms the match.
Downstream of this overflow
The next gauge downstream that the river map places is Cowbridge FWS River Station (Thaw), 3.2 km along the river.
A river gauge measures the level of the river; it does not measure this overflow's discharge, and a spill does not by itself explain a change there. Traced on OS Open Rivers (edition 2026-04), which leaves out many small channels.
Contains OS data © Crown copyright and database rights 2026.
Discharges we have recorded
18 discharge periods since 5 Jan 2025. 17 of them come from Dwr Cymru Welsh Water's own event-duration-monitoring records (published by the company, Jan 2025 – Dec 2025); the live feed adds anything after that. The official annual count is the figure to quote.
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6 h 15 min
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29 d 20 h
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15 min
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45 min
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4 h 45 min
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15 min
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45 min
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3 h 0 min
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45 min
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5 h 0 min
Show 8 earlier
| Started | Ended | Discharge time |
|---|---|---|
| 3 h 30 min | ||
| 5 h 30 min | ||
| 4 h 0 min | ||
| 4 h 30 min | ||
| 15 min | ||
| 15 min | ||
| 1 h 30 min | ||
| 45 min |
The year figures above use the EA's 12/24-hour counting method, so they are comparable with the official figures; the monitor log's 27 raw blocks were merged into 18 continuous discharge periods (gaps under 15 min joined).
What the feed showed
FloodRadar's own record of every change of state Dwr Cymru Welsh Water's live feed has shown for this overflow, kept since : 1 state. The feed publishes its status now and its latest discharge, nothing older; the discharges above are read from this. It is here so the figures can be checked.
Show the last 1 states
| Seen | Status | Since | Latest discharge |
|---|---|---|---|
| Not discharging | → |
Rain nearby last 30 days
Nearest live rain gauge: Cowbridge STW Raingauge, 3.0 km away. Brown shading = when this overflow was discharging; ▼ = a discharge start.
Overflow shading is a timing match, not proof of cause — heavy rain and spills share a trigger. Times come from the water company’s event-duration monitor (site status only; no discharge volume is published).
Where it is
Tell me when this overflow discharges
One message when the company's monitor reports a new discharge here. At most one every 6 hours.
Setting this alert needs JavaScript. The alerts you already have are on your alerts page.
The alert repeats the monitor's status: whether the overflow is discharging, not how much or why. It can only tell you about a discharge that starts after you turn it on.
Concerned about this overflow?
Report pollution you can see or smell to the regulator straight away; the company handles complaints about the overflow itself.
Live status: © Dŵr Cymru Welsh Water, from its Storm Overflow Map. Spill-event history: © Dŵr Cymru Welsh Water's published EDM start/stop records. Annual figures: The Rivers Trust EDM compilation, © Dŵr Cymru/Welsh Water, Open Government Licence. Times are shown in UK local time. FloodRadar republishes the monitor's status; it does not measure discharges itself.