Locks and weirs on the River Thames
These lock and weir combinations are used for controlling the flow of water down the river, most notably when there is a risk of flooding, and provide for navigation above the tideway.
They are referred to by Asserius Menevensis in the ninth century and Magna Carta (1215) states that "weirs, for the time to come, shall be demolished in the Thames and Medway, except on the sea coast."
On the lower section, the river was tidal as far as Staines until the beginning of the 19th century and was under the control of the City of London.
The principle of lock/weir combination, which maintained the depth of water for navigation and reduced the danger of flooding, was extended over the tidal section as far as Teddington in a series of locks built after 1810.
The opening of the Thames and Severn Canal from Lechlade in 1789 led to the building of many of the locks upstream of Shiplake.
In 1866 the Thames Conservancy became responsible for all river management and installed more locks over the years, the last being Eynsham and King’s in 1928.
Locks were often built adjacent to islands and therefore many are situated in remote locations, hard to find and can only be reached on foot.
The Environment Agency has the responsibility of managing the flow of water along the length of the river to prevent flooding on particular reaches and to maintain navigation depths.
[4] The Agency cannot legally stop navigation when the red boards are out, but continuing to travel is inadvisable and may invalidate a boater's insurance.
Today some weirs are often used recreationally by kayakers and canoeists for activities such as whitewater slalom and playboating.
This towpath has formed the basis for the Thames Path which runs between the source and mouth of the river.
These have now almost all disappeared and the Thames Path has to be diverted to the nearest bridge, often a considerable distance, to cope with this.
[7][8] Most of the older flash locks have disappeared and there are only three ferries still operating (Weybridge, Hampton and Hammerton's).
Nearly all of the older weirs and most of the current ones once had associated mills, fifteen of which are mentioned in the Domesday book, but very few of these survive.
