Nannerch Storm Overflow

Year by year

Dŵr Cymru Welsh Water's annual Event Duration Monitoring return to Natural Resources Wales (12/24-hour spill count), as compiled by The Rivers Trust. 2026 is our own running count, the same way, from the live feed since 28 February (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.

"No data" means the monitor was not working or not required to report that year — not zero.

Discharges we have recorded

426 discharge periods since 6 Jan 2021. 426 of them come from Dwr Cymru Welsh Water's own event-duration-monitoring records (published by the company, Jan 2021 – Jun 2024); the live feed adds anything after that. The official annual count is the figure to quote.

• Tue 4 Jun 2024, 18:15
  13 h 15 min
  ended 08:00 · EDM log · 3 blocks · over 13 h 45 min
• Tue 4 Jun 2024, 00:00
  3 h 15 min
  ended 03:15 · EDM log
• Sun 2 Jun 2024, 21:30
  15 min
  ended 21:45 · EDM log
• Sun 2 Jun 2024, 15:15
  3 h 45 min
  ended 19:00 · EDM log
• Sun 2 Jun 2024, 08:00
  15 min
  ended 08:15 · EDM log
• Sun 2 Jun 2024, 05:15
  15 min
  ended 05:30 · EDM log
• Sun 2 Jun 2024, 01:15
  30 min
  ended 02:00 · EDM log · 2 blocks
• Sat 1 Jun 2024, 23:15
  45 min
  ended 00:15 · EDM log · 2 blocks
• Sat 1 Jun 2024, 20:30
  15 min
  ended 20:45 · EDM log
• Sat 1 Jun 2024, 16:30
  3 h 15 min
  ended 20:00 · EDM log · 2 blocks

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 519 raw blocks were merged into 426 continuous discharge periods (gaps under 15 min joined).

Concerned about this overflow?

Report pollution you can see or smell to the regulator straight away; the company handles complaints about the overflow itself.