PLA Issues Thames Safety Warning

Persistent heavy rain in southern England is causing very strong and fast flows in the Thames west of the capital. The abnormally high volumes of water flowing off the land has resulted in flows on the tidal Thames between Teddington and central London many times greater than normal.

This very strong ‘fluvial flow’ – up to four times stronger than normal – has led to a number of accidents involving man-powered vessels. In January there were 20 rescues by the RNLI, of which four were capsized rowing boats. So far 15 rowers have been pulled from the water.

In these incidents, river users have been caught by the severe strength of flow and swept onto moorings and piers. In one case, nine rowers had to be rescued when they were swept under moorings and their boat broken by the strength of the River. In another incident the coaching launch also foundered.

The Port of London Authority (PLA) which oversees safety on the tidal Thames has issued formal safety warnings to all recreational craft users and has also written directly to schools, colleges and universities. A particular concern is over young and novice crews attempting to row during these fast river flows.

The PLA has also introduced a new web-based safety indicator system. The ‘Ebb Tide Flag Warning’ system alerts rowers, canoeists, and other small recreational vessels of conditions on the river. This system is mainly for when the ebb tide and fluvial flows combine to make river conditions very perilous.

Please take note of the new Ebb Tide Flag Warnings.

PLA chief harbour master David Phillips explained: “The recent prolonged rain is resulting in immensely powerful flows on the tidal Thames in west London many times greater than normal.  This makes it extremely challenging for even the most experienced rower or canoeist.

“We have therefore introduced a simple ‘Flag Warning’ system on our website which recreational users can check before they head out.  If a red flag is showing, man-powered vessels are advised not go out.  If a yellow flag is showing, young people and those that do not regularly use the tidal Thames are advised not go out.

“The Thames in west London is a centre for rowing and paddling activities by all age groups.  We have highlighted the current hazards to novices and young people – as these conditions are challenging enough for experienced adults.  We want first experiences of the Thames to be in safer conditions.”

Martin Humphrys, chairman of the Thames Regional Rowing Council (TRRC) said: “The tidal Thames is flowing at an unprecedented rate: even oarsmen who have been on the river 50 years man and boy have never experienced such conditions. I cannot emphasise too strongly the potential hazards to rowers at this time.”

The PLA expects the strong river flow to continue for some weeks, even if the weather improves.

The new tidal flow alert system can be found at: and

With each flag warning, the following advice will be issued, which all recreational craft users should consider carefully before venturing onto the tidal Thames:


Extreme Caution – EBB TIDE Very Strong Fluvial Flows

Fluvial flows are very strong. Conditions are difficult and dangerous. All man-powered vessels are advised not to go afloat on the ebb tide.


Caution – EBB TIDE Strong Fluvial Flows

All river users of man-powered vessels should navigate with extreme caution and consider whether it is safe for them to go afloat on the ebb tide.

PLA advise man-powered vessels – in particular schools, novices, junior crews – or those that do not usually use the tidal Thames not to go afloat on the ebb tide.


Average Fluvial Flows

All river users to navigate with caution and maintain a proper look out.


Caution – Low Fluvial Flows

Tidal flow is lower than usual. River users should expect lower than predicted tides especially around low water.