Why the River Ely keeps flooding the same villages

The River Ely at St Fagans reached at least 3.668 metres at 5am on Sunday 25 October, according to Natural Resources Wales. That is 3cm below the level it reached in Storm Jorge in February 2020 and 6cm below the highest NRW has recorded there, 3.726m in September 2008. The gauge stopped updating after that reading, so the true peak is not known. Storm Boelo put flood warnings on four stretches of the Ely this weekend, at Talbot Green, Peterston-super-Ely, St Fagans and Ely Bridge in Cardiff. All four had been lifted by Sunday afternoon.

The same villages, again

NRW's records show how often the same places are warned. At Peterston-super-Ely this was the fifth flood warning since February 2025, after warnings on 23 February, 11 November, 1 December and 9 December 2025, three of those inside a month last winter. St Fagans has now had five warnings since January 2024: 2 January and 21 February 2024, 19 November 2024, 24 February 2025 and this weekend. At Ely Bridge in Cardiff, the warning issued at 4.20am on Sunday was the first since January 2023 and the fifth since September 2019. For Talbot Green, this weekend's warning is the only one on NRW's record for that area.

Why it rises so fast

NRW's flood risk management plan for south central Wales describes the north of the region as steep valley slopes above narrow, heavily built-up valley floors, with roads, railways, businesses and homes "typically located close to rivers". In Storm Dennis in 2020, it said, rivers across the region "responded quickly to the rainfall falling across already saturated catchments". That is the pattern this weekend: rain on ground already wet from earlier storms. NRW's St Fagans warning, issued at 10.47pm on Saturday, expected the river to rise for six to eight hours, and the gauge was still climbing at 5am.

What has been done, and what has not

At Ely Bridge, NRW set out plans in 2021 for a tree catcher, seven poles in the river upstream of Wroughton Place, to stop debris blocking the bridge. It estimated the scheme would protect about 490 properties in a 1-in-100 flood. NRW said 27 properties flooded near the bridge in September 2008, with further flooding in 2011, 2012 and 2020. Upstream, Pontyclun is one of the south central Wales communities where NRW plans action. In its plan published in November 2023, a study of ways to reduce river flood risk at Pontyclun and an improved flood warning service were both listed as short-term measures, due within two years, and marked "not started". A hydraulic model of the river there was under way.

Check the warning for your area

A flood warning means flooding is expected and people should act; an alert means flooding is possible and people should prepare. NRW's live service shows current warnings by area, and Floodline is on 0345 988 1188. You can sign up for free warnings for a specific area through NRW.