Editing River Stour, Suffolk (section)

==Water supply==
The river plays an inportant role in the supply of drinking water to residents of Essex. Langham Mill had ceased to operate by 1924, and in 1928 South Essex Waterworks (now [[Essex and Suffolk Water]]) obtained an Act of Parliament ([[18 & 19 Geo. 5]]. c. lxxix) granting them permission to demolish it, in order to construct a pumping station on the site. It was licensed to abstract {{convert|12|e6impgal|Ml}} per day,<ref name=flatford>{{cite web |url=https://www.flatfordandconstable.org.uk/history-of-the-stour/water-abstraction-1914-present/?doing_wp_cron=1706361317.9287281036376953125000 |archive-url=https://web.archive.org/web/20240127131929/https://www.flatfordandconstable.org.uk/history-of-the-stour/water-abstraction-1914-present/?doing_wp_cron=1706361317.9287281036376953125000 |archive-date=27 January 2024 |url-status=live |title=Water Abstraction 1914 – present |publisher=Flatford and Constable}}</ref> which was treated at a works to the west, and then pumped to a reservoir at [[Danbury, Essex|Danbury]], from where it flowed to another reservoir at [[Herongate]], suppliying customers in [[Romford]], [[Ilford]] and [[Barking, London|Barking]], Essex, in what is now part of [[Greater London]].{{sfn|ESW|2006|p=6}} Reconstruction of the locks at Stratford, Dedham, Flatford and Brantham was a condition of the planning consent for the works.<ref name=flatford/> Although not a listed building, the pumping station was added to the [[Listed building#Locally listed buildings|Local List]] in 2020. It is constructed of concrete with a pitched roof, in the [[International Style|International Modernist style]] popular at the time, and is painted white. At the treatment works, the control room, primary filter house and chemical house are all built in the same Modernist style, and were listed because they form a good example of the style in largely unaltered form.<ref>{{cite web |url=https://colchesterheritage.co.uk/Designation/DCC26127 |archive-url=https://web.archive.org/web/20240127155602/https://colchesterheritage.co.uk/Designation/DCC26127 |archive-date=27 January 2024 |url-status=live |title=Local List: Langham Water Treatment Works |publisher=Colchester Heritage Explorer |date=3 September 2020}}</ref> There is a detached house and six semi-detached houses built in a similar style to the south of the works, probably designed as housing for the staff, and a service reservoir to the east with its own Modernist pumping station.<ref>{{cite web |url=https://colchesterheritage.co.uk/Monument/MCC5206 |archive-url=https://web.archive.org/web/20240127160040/https://colchesterheritage.co.uk/Monument/MCC5206 |archive-date=27 January 2024 |url-status=live |title=Industrial record MCC5206 – Langham Waterworks, Boxted |publisher=Colchester Heritage Explorer |date=3 September 2020}}</ref>

[[File:Water Pumping Station - geograph.org.uk - 4145560.jpg|thumb|right|The Stratford St Mary pumping station was built in International Modernist style in the 1930s.]]

Although the Langham pumping station was completed in 1932, the company was convinced that it would be short of water by 1940, and obtained a second Act of Parliament, the South Essex Waterworks Act 1935 ([[25 & 26 Geo. 5 (1935)|25 & 26 Geo. 5]]. c xlviii), to allow it to build an extraction point at Stratford St Mary. Water would be pumped southwards to [[Abberton Reservoir]], construction of which was authorised by the same Act.{{sfn|ESW|2006|p=6}} The consents allowed the company to extract up to {{convert|35|e6impgal|Ml}} per day, but required that {{convert|4|e6impgal|Ml}} per day must continue down the river to Flatford and beyond. This was more than the river could supply, and so only the minimum allowed continued downstream.<ref name=flatford/> This reduced flow caused tides to flow upstream as far as Flatford, and the salt content of the tidal water was highly detrimental to the flora and fauna of the river corridor. The solution adopted was to build a further extraction point at Brantham, which meant that the flow past Stratford St Mary could be increased to {{convert|7|e6impgal|Ml}} per day, and the extra abstracted at Brantham.<ref name=flatford/>

The continued expansion of housing stocks in south-east Essex meant that still more water was needed and in 1964, the Ely-Ouse to Essex Transfer Scheme was initiated. Water from the [[River Great Ouse]] was transferred along the [[Cut-off Channel]] to an intake at Blackdyke, from where it flows by gravity to a pumping station at [[Kennett, Cambridgeshire|Kennett]]. It is then pumped to [[Kirtling|Kirtling Green]] where it discharges into Kirtling Brook, a tributary of the Stour. The extra water flows along the Stour, where some of it is abstracted by a pumping station at [[Wixoe]] for transfer by pipeline to [[Great Sampford]] where it discharges into the River Pant, the name of the upper reaches of the [[River Blackwater, Essex|River Blackwater]]. The remaining water increased the flow on the Stour to the pumping stations further downstream.{{sfn|ESW|2006|p=22}} In 2006, further extensions were made to the scheme, as part of a plan to increase the capacity of Abberton Reservoir by 60 percent. Essex and Suffolk Water can extract {{convert|99|e6impgal|Ml}} per day from the Great Ouse, and the Kirtling Brook was too small to cope with this amount. A gravity pipeline was therefore built between Kirtling Green and Wixoe. Downstream, a new pumping station was built at [[Wormingford]], which supplies a pipeline running to the western end of Abberton Reservoir.<ref name=flatford/> By 2019, Brantham was licensed to abstract between {{convert|1.13|and|1.87|e6cuft|Ml}} per day, which flows from the river to the Brantham pumping station by gravity, and is then pumped to Abberton Reservoir by one fixed-speed and two variable speed pumps.{{sfn|Wilson|Packard|2019}}

To comply with the Eels (England and Wales) Regulations 2009, new screens were required on the intake from the river at Brantham, to prevent young [[eel]]s, known as elvers, from being sucked into the machinery and killed. The new screens were positioned on the river side of the existing intake structure, and the rotating bandscreen was supplied by Hydrolox in 2019. It is {{convert|3.9|m|ft|order=flip}} wide and {{convert|4.7|m|ft|order=flip}} tall, and the {{convert|0.079|in|mm|0|adj=on}} mesh was much finer than the course mesh originally in use at the site.{{sfn|Wilson|Packard|2019}} A comprehensive upgrade of the Stratford St Mary's pumping station was undertaken in 2020, in view of the ageing technology and the fact that it is now licensed to abstract {{convert|164|Ml|e6impgal|order=flip}} per day, more than four times the amount for which it was originally designed. The pumps were replaced, allowing the volume of water removed from the river to vary between {{convert|20|Ml|e6impgal|order=flip}} per day to the full amount of the licence. New screens were required on the intake from the river, to protect elvers. A rotating screen supplied by Hydrolux was selected after considering various options, and this was cantilevered off the existing bandscreen building, to minimise disturbance to the river bed.{{sfn|Packard|2020}}