Editing Bow Back Rivers (section)

===Regeneration===
The rivers were run down by the 1920s and, with high unemployment in the area, West Ham Corporation and the Lee Conservancy Board applied for a government unemployment relief grant, with which to fund major improvements. In addition to work on the channels, Bow Tidal Lock was duplicated, Marshgate Lock was rebuilt further east as City Mill Lock, and a second new lock at Carpenters Road was constructed. It used up-and-over radial gates operated by winches, rather than the traditional mitre gates used at City Mill Lock. The gates were quadrant-shaped, and were raised out of the river to allow boats to enter or leave the lock. An act of Parliament was obtained to authorise the work, called the [[River Lee (Flood Relief, &c.) Act 1930]] ([[20 & 21 Geo. 5]]. c. cxcii), and work began the following year. The project was completed in 1935.<ref name=boyes36>{{harvnb |Boyes |Russell |1977 |p=36}}</ref> Before the work, there had been a floodgate on the Waterworks River above its junction with the Three Mills Wall River, and a large pool, the City Mill Pool, connecting to the City Mills River and Saint Thomas Creek. Marshgate Lock was situated to the west of the junction between the Pudding Mill River and Saint Thomas Creek. It was originally built in 1864, by adding a second set of gates to Hunters Gates, a floodgate which had been built around 1847. The reconstructed lock was built on the site of the City Mill Pool, and had two sets of gates at its eastern end, to prevent high tidal levels in Waterworks River flooding the waterways to the west. It was labelled Marshgate Lane Lock on the 1948 map, but was called Ward Lock, after a local councillor, and is now known as City Mills Lock. The course of the Saint Thomas Creek was then straightened, and the original Marshgate Lock was bypassed. Pudding Mill River became a dead end when the lower section was filled in, as was most of the Three Mills Back River, and the floodgate on Waterworks River was also removed.<ref>Ordnance Survey, 1:2500 maps, 1916, 1948</ref>{{sfn |Thomas |2010a}} Reconstruction of the channels included widening City Mill River to {{convert|50|ft|m}}, while Three Mills Wall River and Waterworks River were made twice that width.<ref name=WestHam/>

[[File:River Lea steps.jpg|thumb|left|Steps going down to the tow path, used in the past by horses]]
Prior to the work, the arrangement had been to regulate the navigation with the [[Pond Lane Flood Gates]] and Marshgate Lane tidal lock. The new lock at [[Carpenter's Road Lock|Carpenter's Road]] gave access to the Waterworks River, providing barge access to [[Temple Mills]]. At high tides, the low headroom of the Northern Outfall Sewer aqueduct prevented access to the southern reaches of the system, and to allow access [[City Mill Lock]] was constructed near Blaker Road.<ref>{{cite web |url=http://www.londoncanals.co.uk/bbrivers/citycarp.html |title=City Mill & Carpenters Road Locks |publisher=London Canals |access-date=18 July 2008 |archive-url=https://web.archive.org/web/20080802063053/http://www.londoncanals.co.uk/bbrivers/citycarp.html |archive-date=2 August 2008 }}</ref> In 2005, the lock was partially restored as part of the [[planning gain]] required from the developers of the adjacent Bellamy Homes housing scheme.<ref>{{cite web |url=https://www.guardian-series.co.uk/news/579697.lock-comes-back-to-life/ |archive-url=https://web.archive.org/web/20210217142846/https://www.guardian-series.co.uk/news/579697.lock-comes-back-to-life/ |archive-date=17 February 2021 |url-status=live |first=Tom |last=Hutchison |title=Lock comes back to life |work=East London and West Essex Guardian|date=20 March 2005}}</ref>

The 1930s improvements included the construction of the Prescott Channel, designed to allow flood water to bypass the Three Mills tide mills. The channel included sluices to regulate water levels above it, but these became redundant once the tide mills ceased to operate, and eventually seized up.<ref name=bbc060408/> They were removed soon after parts of the Channelsea River were culverted.<ref name="bw-potted">{{cite web|url=http://www.britishwaterways.co.uk/olympics/history |archive-url=https://web.archive.org/web/20120207004136/http://www.britishwaterways.co.uk/olympics/history/ |archive-date=7 February 2012 |title=Bow Back Rivers – A potted history |publisher=British Waterways |url-status=dead }}</ref>

By the 1960s, only the Saint Thomas Creek, the City Mills River and the Channelsea River were still being used for commercial traffic. A section of the Channelsea River between Stratford High Street and Lett Road was culverted between 1957 and 1958.<ref name=boyes36/> As traffic ceased, the lock structures deteriorated, and by 2006, City Mills Lock and Carpenters Road Lock were officially disused.{{sfn |Nicholson |2006 |pp=102–104}} The [[Transport Act 1968]] had classified most waterways into commercial, cruising and remainder waterways. Remainder waterways were those for which the government of the time could see no economic future, and which would only therefore be subject to maintenance to prevent them becoming unsafe.{{sfn |Squires |2008 |p=64}} The Bow Back Rivers fell into this category, and remained neglected until their full restoration was enshrined in a [[British Waterways]] policy document in 2002.<ref name="bw-potted"/>