|The upper reaches of the River Kennet near Avebury|
The River Kennet has been assigned as a Site of Special Scientific Interest (SSSI) from near its source in Marlborough down to Woolhampton. This is primarily because it has an extensive range of rare plants and animals that are unique to chalk watercourses.
One of the Kennet's sources is Swallowhead Spring near Silbury Hill in the county of Wiltshire, the other being a collection of tributaries to the North of Avebury near the villages of Uffcott and Broad Hinton which flow south past Avebury and join up with the waters from Swallowhead Springs. From there the river flows through Marlborough, Hungerford and Newbury before flowing into the Thames on the reach above Sonning Lock at Reading in Berkshire.
The upper reaches of the River Kennet are served by two tributaries. The River Og which flows into the Kennet at Marlborough and the River Dun which enters at Hungerford. The Kennet's principal tributaries are the River Lambourn, the River Enborne and the Foudry Brook. For six miles to the west of, and through, Reading, the Kennet supports a secondary channel, known as the Holy Brook, which formerly powered the water mills of Reading Abbey.
The River Kennet is navigable from the junction with the Thames at Kennet Mouth near Reading, upstream to Newbury where it joins the Kennet and Avon Canal.
The first mile of the river, from Kennet Mouth to the High Bridge in Reading, has been navigable since at least the thirteenth century, providing wharfage for both the townspeople and Reading Abbey. Originally this short stretch of navigable river was under the control of the Abbey; today it, including Blake's Lock, is administered by the Environment Agency as if it were part of the River Thames.
From High Bridge through to Newbury, the river was made navigable between 1718 and 1723 under the supervision of the engineer John Hore of Newbury. Known as the Kennet Navigation, this stretch of the river is now administered by British Waterways as part of the Kennet and Avon Canal. Throughout the navigation, stretches of natural riverbed alternate with 11 miles of artificially created lock cuts, and a series of locks including; County, Fobney, Southcote, Burghfield, Garston, Sheffield, Sulhamstead and Tyle Mill overcome a rise of 130 feet.
It was formerly known as the "Cunnit". Local historian Michael Dames claims the name is related to the word "cunt", though it is more likely derived from the nearby Roman settlement of Cunetio (now Mildenhall). Following this idea it may be related with the "cynetes" a very ancient people.