The Chew Valley is an area in North Somerset, England, named after the River Chew, which rises at Chewton Mendip, and joins the River Avon at Keynsham. Technically, the area of the valley is bounded by the water catchment area of the Chew and its tributaries; however, the name Chew Valley is often used less formally to cover other nearby areas, for example, Blagdon Lake and its environs, which by a stricter definition are part of the Yeo Valley. The valley is an area of rich arable and dairy farmland, interspersed with a number of villages.
The landscape consists of the valley of the River Chew and is generally low-lying and undulating. It is bounded by higher ground ranging from Dundry Down to the north, the Lulsgate Plateau to the west, the Mendip Hills to the south and the Hinton Blewett, Marksbury and Newton Saint Loe plateau areas to the east. The valley's boundary generally follows the top of scarp slopes except at the southwestern and southeastern boundaries where flat upper areas of the Chew Valley grade gently into the Yeo Valley and eastern Mendip Hills respectively. The River Chew was dammed in the 1950s to create Chew Valley Lake, which provides drinking water for the nearby city of Bristol and surrounding areas. The lake is a prominent landscape feature of the valley, a focus for recreation, and is internationally recognised for its nature conservation interest, because of the bird species, plants and insects.
The area falls into the domains of several councils including: Bath and North East Somerset, North Somerset and Mendip. Some of the area falls within the Mendip Hills AONB. Most of the undeveloped area is within the Bristol/Bath Green Belt. Many of the villages date back to the time of the Domesday Book and there is evidence of human occupation since the Stone Age. There are hundreds of listed buildings with many of the churches being Grade I listed.
There is no clear origin for the name "Chew", found scarcely anywhere else; however, there have been several explanations of the etymology, including "winding water" , the 'ew' being a variant of the French eau, meaning water. The word chewer is a western dialect for a narrow passage, and chare is Old English for turning. Many believe that the name Chew began in Normandy as Cheux, and came to England with the Norman Conquest during the eleventh century. However, some people agree with Ekwall's interpretation that it is derived from the Welsh cyw meaning "the young of an animal, or chicken", so that afon Cyw would have been "the river of the chickens". Other possible explanations suggest it comes from the Old English word ceo, `fish gill', used in the transferred sense of a ravine, in a similar way to Old Norse gil, or possibly a derogatory nickname from Middle English chowe `chough', Old English ceo, a bird closely related to the crow and the jackdaw, notorious for its chattering and thieving.
Many of the villages in the valley have their own parish councils which have some responsibility for local issues. They also elect councillors to district councils e.g. Mendip and Somerset County Council or unitary authorities e.g. Bath and North East Somerset or North Somerset, which have wider responsibilities for services such as education, refuse, tourism etc.
Each of the villages is also part of a constituency, either Wansdyke (which will become North East Somerset) or Woodspring (which is to become North Somerset). The area is also of the South West England constituency of the European Parliament. Avon and Somerset Constabulary provides police services to the area.
The western end of the area of the area (around Nempnett Thrubwell) consists of the Harptree Beds which incorporate silicified clay, shale and Lias Limestone. Clifton Down Limestone, which includes Calcite and Dolomitic mudstones of the Carboniferous period, is found in the adjoining central band and Dolomitic Conglomerate of the Triassic period. There are two main soil types, both generally well-drained. The mudstones around the lakes give rise to fertile silty clay soils that are a dull dusky red colour because of their high iron content. The clay content means that where unimproved they easily become waterlogged when wet, and hard with cracks and fissures during dry periods. The main geological outcrops around the lake are Mudstone, largely consisting of red Siltstone resulting in the underlying characteristic of the gently rolling valley landscape. There are also bands of Sandstone of the Triassic period, that contribute to the undulating character of the area. There are also more recent alluvial deposits beside the course of the River Chew. The transition between the gently sloping landscape of the Upper Chew and Yeo Valleys and the open landscape of the Mendip Hills plateau is a scarp slope of 75 to 235 metres (250 - 770 ft). The predominant formation is Dolomitic Conglomerate of the Triassic period. It formed as a result of desert erosion and weathering of the scarp slopes. It takes the form of rock fragments mainly derived from older Carboniferous Limestone cemented together by lime and sand which hardened to sometimes give the appearance of concrete. The northern boundary is formed by the sides of the Dundry Plateau where the most significant geological formation is the Inferior Oolite of the Jurassic period found on the higher ground around Maes Knoll. This overlays the Lower Lias Clay found on the adjoining slopes. The clays make a poor foundation and landslips are characteristic on the slopes. This area was once connected to the Cotswolds. The intervening land has subsequently been eroded leaving this outlier with many of the characteristics of the Cotswold Plateau. The unusual geological features have been recognised with several sites including; Barns Batch Spinney, Hartcliff Rocks Quarry and Dundry Main Road South Quarry being recognised as Sites of Special Scientific Interest (SSSI) for their geological interest.
The oldest geological formation in the valley is the Supra- Pennant Measures of the Carboniferous period. It is a significant feature towards the north-eastern part of the area and is represented by the Pensford Syncline coal basin, which formed part of the Somerset coalfield. It is a complex formation containing coal seams and is made up of clay and shales. The landscape is typically undulating and includes outcrops of sandstone. Most of the area around Stanton Drew have neutral to acid red loamy soils with slowly permeable subsoils. Soils to the eastern part of the area are slowly permeable clayey and fine silty soils. They are found on Carboniferous clay and shales typical of the Supra-Pennant Measures. They are frequently waterlogged where the topography dictates. They tend towards being acid and are brown to grey brown in colour. In the south and south east of the area there are coal measures which are sufficiently near the surface for coal mining to have taken place around Clutton and High Littleton. In the eastern area of the valley as the River Chew flows through Publow, Woollard and Compton Dando before joining the River Avon at Keynsham there are alluvial deposits of clay soils.
The valley has several areas designated as Site of Special Scientific Interest (SSSI) for biological interest including; Blagdon Lake, Burledge Hill, Chew Valley Lake, Compton Martin Ochre Mine, Harptree Combe and two sites at Folly Farm.
The small and medium-sized fields of the valley are generally bounded by hedges and occasionally by tree belts and woodland, some of which date back to the most evident period of enclosure of earlier open fields which took place in the late medieval period. Hedgerows support the nationally rare bithynian vetch (Vicia bithynica). Mature oak (Quercus) and ash (Fraxinus excelsior) trees are characteristic of the area with occasional groups of scots pine (Pinus sylvestris) and Chestnuts (Castanea sativa). Many elm (Ulmus) trees have been lost in this area, and dead/dying elms are also evident in the surrounding landscape.
Wildlife abounds in the valley, particularly the water birds around the rivers and lakes, with Chew Valley Lake considered the third most important site in Britain for wintering wildfowl. In addition to the water birds including ducks, shoveler (Anas clypeata), gadwall (Anas strepera) and great crested grebes (Podiceps cristatus) a wide variety of other bird species can be seen. These range from small birds such as tits (Paridae) and wrens (Troglodytidae) to Mistle Thrush (Turdidae). Larger birds include Woodpeckers (Picidae) and Common Buzzard (Buteo buteo).
The valley also has a wide variety of small mammals with larger species including; Eurasian Badger (Meles meles) and Deer (Cervidae). The valley is also home to fifteen of the sixteen bats found in England including a roost, at Compton Martin Ochre Mine, for Greater Horseshoe Bats (Rhinolophus ferrumequinum). A rare and endangered species, the greater horseshoe bat is protected under the Wildlife and Countryside Act 1981 and is listed in Annex II of the 1992 European Community Habitats Directive.
Archaeological excavations carried out before the flooding of Chew Valley Lake found evidence of people belonging to the consecutive periods known as Upper Palaeolithic, Mesolithic and Neolithic (Old, Middle and New Stone Age), Bronze Age and Iron Age, comprising implements such as stone knives, flint blades and the head of a mace, along with buildings and graves.  Other evidence of occupation from prehistoric times is provided by the henge monument at Stanton Drew, long barrow at Chewton Mendip, and tumulus at Nempnett Thrubwell. Maes Knoll fort (close to Norton Malreward) in the northern reaches of the valley, on Dundry Down, also formed the starting point for Wansdyke.
There is evidence of Roman remains in particular a villa and burial pits. Some of the artefacts from the valley were sent to the British Museum. Other Roman artefacts from the lake are also on display at the Bristol City Museum and Art Gallery. There are several historic parks and mansion houses, including Stanton Drew, Hunstrete, Stowey House Chew Court, Chew Magna Manor House and Sutton Court. Almost all of the villages have churches dating back to the fifteenth or sixteenth Century.
The area around Pensford was an important coal mining area during the nineteenth and early twentieth centuries, with much of the coal being carried on the Somerset Coal Canal, although there are no working coal mines today. The line of the now disused North Somerset Railway runs south from Bristol crossing over the River Chew on the surviving distinctive viaduct at Pensford and on to Midsomer Norton. The area suffered serious flooding during the storm of 10 July 1968, prompting localised evacuation of populated valley areas in the lower parts of the valley, around Pensford and Keynsham.
The small fields in the western part of the area are particularly characteristic of the Chew Valley and date back to the most evident period of enclosure of earlier open fields which took place in the late medieval period. Fields of this category are generally small in size, regular in outline and often the boundaries preserve the outlines of the earlier strip field system. Regional variations in field size and pattern do occur. For example there is evidence of medieval clearance of woodland on the slopes around Nempnett Thrubwell, south of Bishop Sutton and west and south of Chelwood.
Along with the rest of South West England, the Chew Valley has a temperate climate which is generally wetter and milder than the rest of England. The annual mean temperature is approximately 10 °C (50 °F) and shows a seasonal and a diurnal variation, but due to the modifying effect of the sea the range is less than in most other parts of the UK. January is the coldest month with mean minimum temperatures between 1 and 2 °C (34 - 36 °F). July and August are the warmest months in the region with mean daily maxima around 21 °C (70 °F). In general December is the dullest month and June the sunniest. The south-west of England has a favoured location with respect to the Azores high pressure when it extends its influence north-eastwards towards the UK, particularly in summer. Convective cloud often forms inland, especially near hills, and acts to reduce sunshine amounts. The average annual sunshine totals around 1600 hours. Rainfall tends to be associated with Atlantic depressions or with convection. The Atlantic depressions are more vigorous in autumn and winter and most of the rain which falls in those seasons in the south-west is from this source. In summer, convection caused by solar surface heating sometimes forms shower clouds and a large proportion of rainfall falls from showers and thunderstorms at this time of year. Average rainfall is around 800–900 millimetres (31 - 35 in). About 8–15 days of snowfall is typical. November to March have the highest mean wind speeds, with June to August having the lightest winds. The predominant wind direction is from the south west.
Many of the large houses in the valley have been built or bought by wealthy merchants from Bristol and Bath with many of the local people working for their households. Bess of Hardwick (1527 - 1606) is known to have lived in Sutton Court, Stowey for a few years in the sixteenth century, after the death of her first husband Sir William Cavendish, when she married Sir William St. Loe (or Sentloe or St. Lowe), captain of the guard to Queen Elizabeth, Chief Butler of England, and owner of several manors within the valley and surrounding areas. Around this period a close neighbour was Sir John Popham (1533 - 1607) who was judge and the Speaker of Parliament. In the seventeenth century John Locke (1632 - 1704) an eminent philosopher lived in Belluton and his house is still known as John Locke's cottage. In the eighteenth century the poet John Langhorne (1735 - 1779) became the curate at Blagdon around the time that Augustus Montague Toplady (1740 - 1778) was the priest, and William Smith moved to the valley to make a valuation survey of an estate. He stayed there for the next eight years, working first for Webb and later for the Somersetshire Coal Canal Company.
During the nineteenth century aristocrat George Lyttelton, 4th Baron Lyttelton (1817 - 1876) was a resident. His seat was at Chew Magna, where John Sanger, the circus proprietor, was born in 1816. William Rees-Mogg, former editor of The Times, took the title Baron Rees-Mogg, of Hinton Blewitt, but no longer lives in the village. Jazz clarinetist Acker Bilk lives in Pensford. Richard Brock the natural history film producer, Liam Fox a conservative politician and Dr Phil Hammond a GP and comedian also live in the valley. Robert Hunter of the Grateful Dead lived in Pensford from 1979–1981.
In the past many of the population worked in coal mining, although there are no working mines in the area now. There is still a fairly large agricultural workforce and some in light industry or service industries, although many people commute to surrounding cities for work. According to the 2001 Census the valley has a population of approximately 5000, largely living in one of the dozen or so villages and in some isolated farms and hamlets. The average age of the population is 42 years, with unemployment rates of 1–4% of all economically active people aged 16–74, however these figures are approximations because the ward areas covered and described in the census statistics do not relate exactly to the area of the valley. In the Index of Multiple Deprivation 2004 all of the areas within the valley were considered to be in the most affluent third in England.        
Many of the villages are at the points where it was possible to cross the rivers and streams. Chew Magna is the business centre with a range of shops, banks etc. Many other villages have local shops, often combined with post offices. Most villages have pubs and village halls which provide the majority of the social activity.
The traditional building material is white Lias Limestone; sometimes incorporating red sandstone or conglomerate, with red clay tiled roofs. Buildings, particularly the churches, date back many hundreds of years, for example those at Marksbury and Compton Martin; the latter incorporating a columbarium.
There are hundreds of listed buildings in the valley. Listing refers to a building or other structure officially designated as being of special architectural, historical or cultural significance. The authority for listing is granted by the Planning (Listed Buildings and Conservation Areas) Act 1990 and is presently administered by English Heritage, an agency of the Department for Culture, Media & Sport. Grade I covers buildings of exceptional interest, Grade II* particularly important buildings of special interest and Grade II buildings of special interest. Listed buildings in the valley number five churches dating back to the fourteenth century or even earlier, with grade I status; Church of St Andrew at Chew Magna, Church of St. Bartholomew at Ubley, Church of St James at Cameley, Church of St. Margaret at Hinton Blewitt and Church of St Michael the Archangel at Compton Martin.
At the western end of the valley is the A38 and Bristol International Airport, which means parts of the valley are on the flight path. The valley is also crossed by the A37 and they are joined by the A368. Most of the roads in the valley are small single track lanes with little traffic although a bottleneck often occurs within Chew Magna. The "Chew Valley Explorer" bus route 672/674 provides access to many of the villages in the valley. Cyclists can gain access via part of the Padstow to Bristol West Country Way, National Cycle Network Route 3.
The Monarch's Way long distance footpath crosses the valley.
Chew Valley School is the main secondary school (11–18 years) for the valley. It is situated between Chew Magna and Chew Stoke. The latest (2005) Ofsted Inspection Report describes this specialist Performing Arts College as a mixed comprehensive school with 1158 pupils on roll. The school is popular and oversubscribed with 196 students in the sixth form. The school has been successful in gaining a number of national and regional awards. There are state primary schools (4–11 years) in most of the local villages.
Many of the local villages have football pitches and children's play areas. Gymnasium facilities, squash courts, badminton etc., and outdoor all-weather pitches are available at the Chew Valley Leisure Centre between Chew Magna and Chew Stoke. There are a range of clubs and societies for young and old, including Scout groups, gardening society, and the Women's institute. There are several areas in the valley which the Countryside Agency has designated as access land; Burledge Hill (south of Bishop Sutton)(), Castle Earthworks (between Stowey and Bishop Sutton)(), Knowle Hill (Newtown south of Chew Magna)(), Round Hill (Folly Farm)() and Shortwood Common (Litton) ()
A Bowls club is in Chew Stoke, cricket pitches and teams in Chew Magna and Blagdon. There are several football teams in the valley including Chew Valley Football Club and Bishop Sutton F.C.. The rugby club is based next to the leisure centre. The Bishop Sutton Tennis club is the largest in the valley, there is also a tennis club at East Harptree. Both Chew Valley Lake and Blagdon Lake provide extensive fishing under permit from Bristol Water. The River Chew and most of its tributaries also have fishing but this is generally under licences to local angling clubs. Chew Valley Sailing Club is situated on Chew Valley Lake and provides dinghy sailing at all levels and hosts national and international competitions. There are no swimming pools in the valley, and swimming is not allowed in the lakes, however these are available locally in Bristol, Bath, Cheddar and Midsomer Norton.
Each year the Chew Valley Arts trail takes place in October during which over 50 local artists display their work in 20 or so venues around the valley such as; painting, printmaking, sculpture, decorative glass, pottery, photography, jewellery and sugar craft. The valley and lakes have been an inspiration to many artists and there is a small art gallery at Chew Valley Lake. Live music and comedy events take place in many of the local pubs and village halls, with the village of Pensford holding a music festival every year.