|Etymology||Linked to place name: Cunetio (very likely from Celtic kūn, hound)|
|Towns||Marlborough, Hungerford, Newbury, Reading|
|• location||Swallowhead Spring, near Silbury Hill, Wiltshire, United Kingdom|
|• elevation||200 m (660 ft)|
|Reading, Berkshire, United Kingdom|
|40 m (130 ft)|
|Length||72 km (45 mi)|
|• location||Theale, Berkshire|
|• minimum||0.93 m3/s (33 cu ft/s)21 August 1976|
|• average||9.75 m3/s (344 cu ft/s)|
|• maximum||70.0 m3/s (2,470 cu ft/s)11 June 1971|
|• location||Newbury, Berkshire|
|• average||4.64 m3/s (164 cu ft/s)|
|• location||Knighton, Wiltshire|
|• average||2.50 m3/s (88 cu ft/s)|
|• location||Marlborough, Wiltshire|
|• average||0.85 m3/s (30 cu ft/s)|
|• left||River Og, River Lambourn|
|• right||River Dun, River Enborne, Clayhill Brook, Foudry Brook|
|Status||Largest tributary of outflow river|
The Kennet is a tributary of the River Thames in Southern England. Most of the river is straddled by the North Wessex Downs AONB (Area of Outstanding Natural Beauty). The lower reaches have been made navigable as the Kennet Navigation, which – together with the Avon Navigation, the Kennet and Avon Canal and the Thames – links the cities of Bristol and London.
The length from near its sources west of Marlborough, Wiltshire down to Woolhampton, Berkshire is a 111.1-hectare (275-acre) biological Site of Special Scientific Interest (SSSI). This is primarily from an array of rare plants and animals completely endemic to chalky watercourses.
When Wiltshire had second-tier local authorities, one, Kennet District, took the name of the river.
The pronunciation (and spelling) was as the Kunnit (or Cunnit). This is likely derived from the Roman settlement in the upper valley floor, Cunetio (in the later large village of Mildenhall). Latin scholars state Cunetio is very unlikely to be a Latin derivation, meaning it is a Celtic British name, like most Roman town names in Britain. The frequent Celtic stem "cun-" means "hound", as in the modern Welsh ci, cŵn “dog”.[a]
One of the Kennet's sources is Swallowhead Spring near Silbury Hill in Wiltshire, and others are springs north of Avebury near the small villages of Uffcott and Broad Hinton. These then converge. In these early stages it passes close by many prehistoric sites including Avebury Henge, West Kennet Long Barrow and Silbury Hill. The land drained by the headwaters normally has a deep water table (being in the North Wessex Downs which is mostly chalk as the upper subsoil), thus many stretches are winterbournes when and where precipitation is low and surrounding soils are not so dense with impermeables as to form a surface spring.
The river flows through the towns of Marlborough, Hungerford and Newbury before flowing into the Thames on the reach above Sonning Lock in central Reading, Berkshire.
The Og joins at Marlborough and the Dun enters at Hungerford, followed by the River Lambourn, Enborne and the Foudry Brook. For six miles (10 km) west of Reading's centre, the Kennet, being barraged to maintain its longest heads of water, has a semi-natural secondary channel (a long leat, a corollary), the Holy Brook. This powered the mills belonging Reading Abbey.
The River Kennet is a haven for various plants and animals. Its course takes it through the North Wessex Downs Area of Outstanding Natural Beauty, and the river between Marlborough and Woolhampton is designated a Site of Special Scientific Interest (SSSI). The protection that this status affords the Kennet means that many endangered species of plants and animals can be found here. The white drifts of water crowfoot (Ranunculus) in early summer are characteristic of chalk and limestone rivers; there are superb displays by the footbridge at Chilton Foliat, and by the road bridge in Hungerford.
Animal species such as the water vole, grass snake, reed bunting, brown trout, and brook lamprey flourish here, despite being in decline in other parts of the country. Crayfish are very common in parts of the river. However, most, if not all, are now the alien American signal crayfish, having escaped from crayfish farms, which has replaced the native white-clawed crayfish in most southern rivers, although a small population still survives in the River Lambourn. And not forgetting the foundation to supporting this varied wildlife food chain, there are the insects, many hundreds of species, common and rare, that can be found in and around the River Kennet. There are large hatches of mayflies, whose long-tailed, short-lived adults are a favourite food of trout; many species of water beetle and insect larvae. Caddisflies are also very numerous, especially in the late summer. Alongside the river, the reed beds, grasses and other vegetation support many other insect species, including the scarlet tiger moth, poplar hawk moths and privet hawks.
Throughout its history, water mills on the Kennet have been a source of power for various pre-industrial and industrial activities. In places the river has been built up to provide an additional head of water to drive the mills. Three mills remain in Ramsbury alone, and there are many disused or former mill sites, such as at Southcote, Burghfield, Sulhamstead, Aldermaston, Thatcham, Newbury, and Hungerford. Aside from the mills, in the 17th and 18th centuries the river water was also used for the brewing and tanning industries of Ramsbury and Marlborough.
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.
Water quality of the River Kennet in 2019:
|Upper Kennet to Marlborough||Moderate||Fail||Moderate||27.878 km (17.323 mi)||150.231 km2 (58.005 sq mi)|
|Middle Kennet (Marlborough to Hungerford)||Good||Fail||Moderate||34.037 km (21.150 mi)||57.123 km2 (22.055 sq mi)|
|Middle Kennet (Hungerford to Newbury)||Moderate||Fail||Moderate||49.227 km (30.588 mi)||84.872 km2 (32.769 sq mi)|
|Kennet (Lambourn confluence to Enborne confluence)||Moderate||Fail||Moderate||16.626 km (10.331 mi)||38.254 km2 (14.770 sq mi)|
|Lower Kennet (Sheffield Bottom to Reading)||Moderate||Fail||Moderate||29.791 km (18.511 mi)||48.887 km2 (18.875 sq mi)|
In July 2013 the Environment Agency investigated an insect kill which resulted when a small quantity (estimated to be two teaspoonfuls (10 millilitres)), of chlorpyrifos, an organophosphate insecticide used in ant poison and available in garden centres, was flushed into the river killing the freshwater shrimp and most other arthropods on the stretch of the river between Marlborough and Hungerford. The dead insects sank to the bottom of the river and rotted, resulting in a bad smell, but no fish seemed to have been killed. However, without insects and shrimps to feed on, many of the fish, birds and amphibians that use the river would be likely to fade away and die. The poison was diluted and removed by the flow of the stream.