River Ash, Surrey

River in Surrey, England

Alluvium on gravel (save for London Clay outcrops, such as Harrow on the Hill, Hampstead Heath and the Grim's Ditch (Harrow)) is the soil setting of the north bank, west of the City of London as far as the Chiltern Hills. As to topsoil the river marks a divide between permeable shallow gravelly topsoil for many miles to the north and almost impermeable alluvium to the south. A very thin, agriculturally prosperous alluvial belt by the River Thames 0.6 mile (1 km) to 3 mile (5 km) away was caused by deposition from seasonal floods. This prevents for the whole course the rivers joining despite their proximity. As the gravel former terraces of the Thames very gently slope from north to south no abrupt halts to the water table exist no springs arise and only modest interaction with the Thames Basin's water table. The sources are water from the Colne and run off principally of a fresh water waterworks.

Ashford gains its name from the river, forming the southern limit of all but its east half (ex manor demesne and Common). Relevant maps date to medieval times, showing course changes, some clearly man made. The earliest at close resolution recounts various channels by Shepperton Studios (Littleton Manor demesne), commissioned by the Lord of Shepperton Manor, two miles to the south. This refers to the monks of Westminster, who caused the local widening into heads of water as fish "pond"s.

Short residential streets in north eastern Staines upon Thames were flooded in February 2014. At least 80 homes reported internal, outhouse or grounds flooding to the Environment Agency. Causes were complicated by the interweaving of an aqueduct which overflowed and various sluices; one found to be inadequate, another not best operated. A precedent for the river was in 1947 when flooding was widespread in the Thames Valley.

Upgrade of the fresh water treatment works at Ashford Common (1994–95) by Thames Water Utilities caused greater steady outflow east of the M3. This heightened flood risk to properties abutting in Shepperton. Public budget work then arose, the River Ash Flood Alleviation Scheme of the Environment Agency. Deep holding troughs exist before the works run off discharge and in Sunbury Golf Course a relief channel exists, bridged twice, built in January to May 1995 for £450,000.

Squires Bridge is a long two arch bridge which has substantial neat (ashlar) stone dressings, such as seven balusters across six lightly recessed stone panels, each side, each arch. It has statutory protection and recognition in the initial starting category (Grade II). It was built in about 1870, partly by commission of the Wood family whose Manor House, standing at today's Shepperton Studios, had a costly fire in 1874. Its central newel (pilaster) as to its outer, upstream side has a coat of arms with three swords, not the family's which was that of a bull, instead that of Middlesex.

Ash Link Local Nature Reserve, the first nature reserve in Spelthorne, was opened by the Mayor of Spelthorne in June 2012. It is managed by volunteers from Spelthorne Natural History Society and subgroup of its Friends in partnership with the Borough who own the land. It is in Shepperton, either side of the M3 as Splash Meadow in the south east and Nutty Wood to the north west. The Reserve is linked by a large footbridge and has a variety of wildlife, mixed woodland, wildflower glades, ponds and the river. Conservation over the years has helped to increase the biodiversity of the area and as well as monitoring and recording the wealth of species; the volunteers continue to enhance the site for the benefit of the wildlife and enjoyment of the public. In 2017 the Ash Link Local Nature Reserve was awarded a Gold Medal in the 'South and South East in Bloom' competition run by the Royal Horticultural Society; the next year the Friends received the 'Queen's Award for Voluntary Services.' On the edge of Shepperton Studios (the Littleton "new" manor house estate), Studios Walk is a strip of Ash side habitat. A surfaced path runs from west to east ends offering easy access and viewpoints over the river, unsurfaced paths also exist. The woodland onsite is ecologically important thanks to numerous veteran oaks of type quercus robur which promote a vast array of invertebrates. An oak tree can support 100 times the invertebrate abundance of acer pseudoplatanus sycamores. which, in turn, sustain bats, mice and squirrels. The rough bark and natural crevices that appear over time make ideal roosting. The natural progression of woodland into dead wood make the site an ideal habitat for stag beetles lucanidae, iconic insects requiring large sections of dead wood to feed and for the development of larvae. Kingfishers of type alcedo atthis often are seen at these zones using the river as a foraging corridor. The marginal and in channel habitat along with the sections of still water also offers ideal refuge for amphibians. In 2016 a project was undertaken alongside the Environment Agency which formed part of the ColnCAN's "Weir today: gone tomorrow" programme. The works were the notching of a weir, installation of a new control structure and restoring a relic channel to serve as a by pass channel to the main weir. The principal aim being to improve fish passage. About 600 metres was restored to provide favourable flow variations and enhanced aquatic and terrestrial habitat for a broad range of species.