River Wandle
The River Wandle is a tributary of the River Thames in south London, England. With a total length of about , the river passes through the London boroughs of Croydon, Sutton, Merton and Wandsworth, where it reaches the Thames. A short headwater – the Caterham Bourne – is in Surrey, the historic county of the river's catchment. Tributaries of the Wandle include the River Wrythe and the Norbury Brook. The name "Wandle" is thought to derive from a back-formation of Wandsworth (Old English "Wendlesworth" meaning "Wendle's Settlement”). The Wandle Trail follows the course of the river from Croydon  to Wandsworth. History and boundaries. In the pleistocene before the carving of the Mole Gap, water lapped the north of the area between the North Downs and Greensand Hills known as the Vale of Holmesdale taking the Caterham or Coulsdon Bourne routes, to form the much less deep Merstham Gap, a wind gap. In more recent times, precipitation on the local central, small section of the long escarpment percolates through the chalk and reappears as springs in central Croydon, Beddington, and Carshalton. The occasional stream, known as the Bourne, which runs through the Caterham valley (and Smitham Bottom in Coulsdon ) is a source of the River Wandle but only surfaces after heavy rainfall. A series of ditches and culverts carries the water from Purley to Croydon. For many centuries the River Wandle rose from a spring by Brighton Road to enter and flow through the Haling neighbourhood in the south of Croydon. It ran along Southbridge Road and upon reaching Old Town it reached a maximal across and began to divide into smaller channels. The grounds of the Old Palace and Scarbrook Hill had springs engineered with ponds, streams and canals where fish swam, especially trout. Over the years it  became renowned for its fish, and is mentioned in works such as William Camden's "Britannia" (1586) and Izaak Walton's "The Compleat Angler" (1653). Lord Nelson would fish in its waters, leading his mistress, Lady Hamilton, to rename the Wandle, as it flowed through her garden, the "River Nile", in Nelson's memory. However, as Croydon's population grew and use of the water closet increased, the Old Town streams became little more than open sewers and were filled in or culverted from 1840 after outbreaks of typhoid and cholera. The river then flowed through Pitlake and on through  two marshy fields – Froggs Mead and Stubbs Mead – drained to form Wandle Park in 1890. Local springs were used to form a boating lake in the park, but frequent drying up problems led to the lake being filled in and the river was culverted in 1967. In 2012, the Wandle was restored to the surface in Wandle Park. From there, the river continues underground, through where the gas works used to stand, under the Purley Way road past Waddon Ponds and appears on the surface at the road Richmond Green, where a small green buffer to its south acts as  the green after the footpath at the end of Mill Lane in Waddon, Croydon. For part of its length, the Wandle forms the boundary between the London Boroughs of Croydon and Lambeth and, further downstream bounds Merton and Wandsworth. Shortly before reaching the Thames the navigable Bell Lane Creek splits from the river, rejoining close to the confluence. Localities adjoining the river and its mentioned main tributaries include: Croydon, Waddon, Beddington, Wallington, Carshalton, The Wrythe, Hackbridge, Mitcham, Ravensbury, St Helier, Morden, Merton Abbey, Colliers Wood, South Wimbledon, Summerstown, and Wandsworth. Honeywood Museum, in Carshalton Village, includes displays and an interactive  map about the River Wandle and its influence on the life of the area. Headwaters. Intermittently visible watercourses. Rain falling on part of the North Downs mainly filters through a thin topsoil into chalk and emerges on the spring line and in gentle ravines carved by water erosion. At the top of the catchment the Wandle has four main headwaters historically noted as winterbournes — streams which only flow when the water table is high. Two such streams, culverted, combine in Central Croydon beneath Bourne Street to form the Wandle which emerges immediately north-west in Wandle Park. The Wandle is  piped part-way-through neighbouring New South Quarter to flow under Purley Way (formerly Waddon Marsh Lane) and part of its retail park. From its central gathering the flow is westwards (or WSW) until merger with the Wrythe. On its route the early Wandle surfaces to receive springs at a long lake "Waddon Ponds" beside Mill Lane, Croydon. The Coulsdon Bourne and linked Caterham Bourne south of Croydon town centre ran in wet seasons. They have been culverted since before 1900. When the water table is medium or high these waters meet at Purley, run in a culvert the length  of the Brighton Road, South Croydon, and merge into the surface water drains and culverts in the town centre (which become much of the above stream). The River Wrythe. The River Wrythe rises in the Carshalton Ponds, at about AOD, and flows north-eastwards for a distance of just over before joining the River Wandle at Wilderness Island. The river gives its name to the neighbourhood of The Wrythe in Carshalton. The Norbury Brook. The Norbury Brook is in its western section for parochial boundaries called the Graveney River. Aggregated streams combine under Grant Road, Addiscombe. Straightened, it roughly bounds  Croydon and Lambeth Boroughs forming the ancient boundary of Croydon and Norwood (once the large woodland in Norbury parish). Its long, culverted mouth with the Wandle is in Tooting Graveney – it meets the Wandle fronting the Haydons Road part of Wimbledon in the Borough of Merton. Use. The river has been well-used since Roman times; in the 17th century Huguenots were attracted by the cloth and textile mills which lined the banks of the river. It was heavily industrialised in the 18th and 19th centuries (the industrial revolution), and was declared one of the most polluted rivers in England . The main industries then were tobacco and textiles. The river was used to power 68 water wheels, of which only a few survive, such as at Merton Abbey Mills for paper, print and tapestries. The Liberty print works and Merton Board Mills before early 20th century demolition dominated the riverscape (replaced by a two-retailer clothes and food megastore in Merton). Local concentration of heavy industry resulted in multiple leats being cut during the 18th century; a remnant of the old courses, the Pickle, is two ditches, one runs beneath Liberty Avenue. The former leat has become the main river  next to Merton Abbey Mills craft village. Clean-ups of the Wandle have improved the water quality dramatically, leading to a return of the river's brown trout. This improvement in water quality has also seen other fish thrive with stocks of chub, roach and dace all flourishing once again with the most popular angling spots being in Hackbridge and Colliers Wood. Local nature reserves. A stretch of the river between Trewint Street and Plough Lane in Merton has been designated as the Lower Wandle Local Nature Reserve (LNR). It is lined by mature trees and patches of grassland. South  of the Lower Wandle, an area of wetland between the River Wandle and the Wandle trail is the Wandle Meadow Nature Park LNR. Another LNR adjacent to the Wandle is the Wandle Valley Wetland in Carshalton. In 2017, a new nature reserve was created in Bell Lane Creek in the Wandle Delta, by removing a half-tide weir that had been installed in the 1980s at the junction of the Wandle and the River Thames. This had been built as the first part of a project to create a marina, however it had ceased to work some years previously. Restoring  it would allow the tide to clear out silt and restore a natural tidal river. In addition, a section of the Thames river wall was lowered as part of the Wandsworth Riverside Quarter residential development, to allow reeds and vegetation to develop and provide a more natural sloping embankment. As part of the project layers of contaminated sediment were dredged from the site, to restore a gravel bed and restore a wildlife habitat measuring roughly a hectare in size. Incidents. 21st century hazardous discharges. In 2007, Sodium hypochlorite was accidentally flushed into the Wandle from Thames Water's Beddington sewage  works. The chemical was being used to clean its tertiary treatment screens. Its use is permitted if captured ("re-circulated") for further treatment. The discharge killed over 2,000 fish of various species. The sewerage undertaker failed to notify the Environment Agency – its site manager thought it was minor. The company apologised; it offered to meet local angling clubs and the Wandle Trust to discuss restocking and long-term support for the Trust's work. The regulator fined the provider £125,000 and legal costs. In 2009 it was the greatest penalty for a one-day unlawful discharge into controlled waters . In 2010 a High Court judge found the fine was under the statutory rules governing pollution penalties "manifestly" excessive, reducing it to £50,000, noting Thames Water had donated £500,000 to clean up the river. Makeup. The predominant geology of the south part is chalk interspersed with flint and narrow alluvial gravel beds in the south. London clay overlaid with patches of gravel topped by deeper humus forms the north; the top soil, tempered by the chalk beneath is less acidic where still seasonally turned in the south. The river has since the 18th century been largely terraformed with  tributary artificial channels (becoming surface water drains) and runoff ditches. It has its relatively few underground (culverted) stretches; these are in Croydon. Water quality. The Environment Agency measures the water quality of the river systems in England. Each is given an overall ecological status, which may be one of five levels: high, good, moderate, poor and bad. There are several components that are used to determine this, including biological status, which looks at the quantity and varieties of invertebrates, angiosperms and fish. Chemical status, which compares the concentrations of various chemicals against known safe concentrations, is rated good or fail . In the 1980s Wandle designated one of the London bus districts. Its logo was a water wheel above the London Transport roundel.