The main chalk stream in Kent is the River Great Stour, being some 50 miles in length there are several tributaries of the Great Stour several of which combine either side of Pledge's mill near Ashford.
The River Upper Great Stour (sometimes referred to as the River West Stour) is usually named on maps as the River Great Stour. It rises south of the village of Lenham and joins with the River East Stour, either side of Pledge's Mill at the bottom of East Hill, Ashford. The combined rivers then continue as the River Great Stour. The River Great Stour then joins the River Little Stour.
The River Little Stour runs for 14.3 km, after initially starting near Lyminge as the Nailbourne (see below) until it joins the River Great Stour at Pluck's Gutter, along with the River Wantsum which flows in from Reculver in the North.
After the confluence of these three rivers, the remaining single channel is known as the River Stour which continues in an easterly direction emptying into the Channel at Pegwell Bay.
Nailbourne at Bishopsbourne, Kent (March 2007)
The River Cray ('cray' meaning clear/pure) is a tributary of the River Darent in southern England. It rises in Priory Gardens in Orpington in the London Borough of Bromley (rainwater falls through nearby chalk and a pond is formed where the chalk meets clay), then flows northwards past the industrial and residential area of St Mary Cray, through St Paul's Cray where there was once a paper mill, through Foots Cray, and enters the parkland of Foots Cray Meadows.
The Nailbourne (sometimes referred to as Nail Bourne) is both a chalk stream and a winterbourne.
The Nailbourne bubbles up beneath St Ethelburga's Well in Tayne Field in the centre of Lyminge. Whilst the stream often holds a plentiful supply of water from Lyminge to Elham throughout the year, it rarely holds any water from Elham to Bishopsbourne even in the winter months. However, in wet years the normally dry ditch can turn into a fast flowing torrent, flooding roads, fields and houses. An example of this was in 2001 when there was extensive flooding throughout the Elham Valley.
Chalk streams in Kent
The River Darent, also known as the River Darenth or Dartford Creek, is a Kentish tributary of the River Thames. Its name is believed to be from a celtic word meaning 'river where oak trees grow' (similar to 'Derwent'). Fed by springs in the hills south of Westerham and Limpsfield Chart in Surrey it meanders for 21 miles in a generally east then northward direction until it arrives into the town of Dartford where it is joined by the River Cray. It then flows northwards and joins the Thames at Crayford Ness.
Notwithstanding it's journey through the heavily populated areas of Greater London, the river is a largely peaceful river. In recent times it was recognised that the flow of the river was reducing dramatically due to over abstraction, and in 1989 it was given the dubious title of 'lowest flow river' in England. Since then much work has been done to address the problems and rectify the situation, including the closure by the Environment Agency of many bore holes along it's length.