Llansilin - Malthouse Cottage (CSO)
Storm overflow run by Hafren Dyfrdwy.
"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
Hafren Dyfrdwy's annual Event Duration Monitoring return to Natural Resources Wales (12/24-hour spill count), as compiled by The Rivers Trust.
"No data" means the monitor was not working or not required to report that year — not zero.
Downstream of this overflow
The next gauge downstream that the river map places is Llanyblodwel (River Tanat), 11.2 km along the river.
Water-sampling points downstream
The nearest Environment Agency sampling points the river map places below Llanyblodwel. Points between this overflow and that gauge cannot be put in order with it on the map, so they are not listed.
- Vyrnwy at Hendre
32 km along the river · Last sampled 10 Oct 2025 · 12 months ago - River Vyrnwy - Melverley Chur
34 km along the river · Last sampled 22 Sep 2026 · 16 days ago - Severn at Shrawardine
46 km along the river · Last sampled 29 Dec 2023 · 2.8 years ago
A sample is dated: it is not the river now, and its results are on its own page. A sample taken after a discharge does not show that the discharge caused what was measured. Samples: Environment Agency Water Quality Archive, © Environment Agency and/or database right 2026, Open Government Licence v3.0.
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. This overflow was placed on the river by its position alone. 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
We hold no discharge periods for this overflow: it has no live feed, and Hafren Dyfrdwy has published no event-level log for it that we hold. The official annual figure above is the record to rely on.
Rain nearby last 30 days
Nearest live rain gauge: Rainfall gauge nr Rhydycroesau, 3.7 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
Concerned about this overflow?
Report pollution you can see or smell to the regulator straight away; the company handles complaints about the overflow itself.
Spill-event history: © Hafren Dyfrdwy, published on Stream (data.streamwaterdata.co.uk) under CC BY 4.0. Annual figures: The Rivers Trust EDM compilation, © Hafren Dyfrdwy, Open Government Licence. Times are shown in UK local time. FloodRadar republishes the monitor's status; it does not measure discharges itself.