Teddington Lock: How it works and why we need it

  Posted: 06.02.21 at 10:00 by Gianna Saccomani

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Teddington RNLI Lifeboat Station is located by Teddington Lock and weir, where the River Thames becomes non-tidal.

Gianna Saccomani interviewed Gemma Riley to find out more about Teddington Lock and how it operates.

There are 45 lock and weir sites on the non-tidal Thames but Teddington is the only site that is crewed 24 hours, as it is the first lock at the non-tidal point.

Teddington Lock and weir are operated and maintained by the Environment Agency.

When the pagers go off and the volunteer RNLI lifeboat crew is tasked to an incident upstream of the lock in the direction of Kingston, the lock keepers give them safe and swift passage through the lock.

The duty RNLI DLA (Deputy Launching Authority) will call ahead and, using the smaller launch lock, the lock keeper will prepare their passage through.


If there is no one on duty, the RNLI lifeboat crew can also operate the locks if needed, having been trained (pre Covid) by the lock keepers.

Using a second set of sluices, the lock can fill up much faster than normal. These sluices are only used by the lock keepers to assist the lifeboats to transit the lock as quickly as possible.

But giving assisted passage to river users is not their only role on the river. Their more important role is to
maintain river water levels.

This is for two reasons. Firstly, to ensure that the water is
navigable and safe and clear of obstructions. After a high tide, there can often be debris in the water and sometimes a boat may have lost its mooring.

Secondly their role is to maintain levels for Thames Water.


Thames Water have an abstraction licence to take water from the Thames to top up reservoirs such as Chertsey and Walton. Approximately 70% of all water supplied to
London is taken from the Thames upstream of Teddington Weir. Topping up occurs constantly.

Gemma Riley, the Environment Agency’s Lead Lock and Weir Keeper at Teddington Lock explains; "There are five full time lock and weir keepers based at Teddington lock (including 3 women!) and in normal times, they would operate 24/7 on three shift patterns.

"This is because there is also a waterways duty desk at Teddington. Any incident on the non-tidal Thames e.g. a police incident, pollution, changing water levels, is reported here.

"Alarms are set if water levels drop too low or rise too high, and then Teddington will alert the local lock if necessary.

"Around 300 people are employed on the waterways on the
non- tidal part of the River Thames. Although upstream of Teddington Lock is non-tidal, a high tide will affect the water levels at Molesey Lock and conversely a weir move (adjustments of the weir gates) in Molesey Lock may affect water levels in Teddington.


"There are 18 gates at Teddington Weir and each is able to be adjusted individually, sometimes at 3 o'clock in the morning if needed."

The pull of the water near weirs can be extremely strong especially when the river flow is high, and the volunteer lifeboat crew at Teddington RNLI have rescued people from the top of the weir - from someone in a kayak who capsized between the towpath in Ham and the side gates to the weir, to a 23-foot cabin cruiser moving downstream on the left-hand side of the river and was not aware that there was a weir in Teddington.

Gemma Riley recommends that all river users, and in particular those using non-motorised vessels such as inflatables and stand-up paddle boards, check the
Environment Agency's river conditions website before setting out.

Currently the river is on red boards, which means that the Environment Agency advises users of all boats not to
navigate because the strong flow makes it difficult and dangerous.

Find out more HERE

Finally, if you do see someone in difficulty in or around the water, please call 999 and ask for the coastguard.

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