River Blackwater (River Loddon)
|This article relies largely or entirely on a single source. (May 2012)|
River Blackwater at Eversley bridge
|Counties||Hampshire, Surrey, Berkshire|
|- left||River Whitewater|
|- location||Rowhill Nature Reserve, Aldershot, Hampshire|
|- elevation||135 m (443 ft)|
|Length||27 km (17 mi)|
|Discharge||for Swallowfield |
|- average||3.07 m3/s (108 cu ft/s)|
|- max||42.3 m3/s (1,494 cu ft/s) (17 September 1968)|
|- min||0.48 m3/s (17 cu ft/s) (17 August 1953)|
|Discharge elsewhere (average)|
|- Farnborough||0.52 m3/s (18 cu ft/s)|
The River Blackwater is a tributary of the River Loddon in England and, indirectly, of the River Thames. It rises at Rowhill Nature Reserve between Aldershot in Hampshire and Farnham in Surrey and runs northwards to join the Loddon near the village of Swallowfield in Berkshire. Along part of its length, the river forms the boundary between Hampshire and Surrey, and then between Hampshire and Berkshire. It rises in Rowhill Nature Reserve, Aldershot Rowhill, an isolated remnant of the extensive heathland that once surrounded Farnborough and Aldershot. After 20 miles (32 km) the Blackwater is joined by the River Whitewater near Eversley. The river gives its name to the small town of Blackwater, Hampshire, upon the river near Camberley.
The River Blackwater runs down the centre of the Blackwater Valley, which is maintained as an open space along the borders of the counties of Berkshire, Hampshire and Surrey. It runs for approximately 30 km, from the source of the River Blackwater at Rowhill Nature Reserve near Aldershot in the south, northwards to Swallowfield where the river joins the River Whitewater and then the Loddon. The Loddon eventually flows into the River Thames near Reading.
Although surrounded by urban development the Valley provides an important green corridor for local residents. As well as the Blackwater Valley Site of Special Scientific Interest (SSSI) and a small part of the Basingstoke Canal SSSI, three nature reserves within the Valley catchment and many other areas have been recognised for their ecological importance. The local planning authorities covering the Valley have designated 31 other areas as ‘Wildlife Sites’. As a result of an improvement programme, wildlife is returning, including the Otter which has been absent for over 40 years, fishing stocks are improving and the construction of the long distance riverside path has opened up much of the riverbank.
A cycle route runs alongside the River Blackwater for most of its length. There is a running club named Blackwater Valley Runners who run there regularly.
The Basingstoke Canal runs east west from the Greywell Tunnel at Greywell to the River Wey. It crosses the Blackwater Valley on an embankment. The River Blackwater used to flow under the embankment in a culvert. Following the construction of the relief road, the Basingstoke Canal now crosses the River Blackwater via the spectacular Ash Aqueduct. Bats that used to roost in the culvert now live in a purpose-built bat house on a nearby island. The new aqueduct affords views of the surrounding countryside. In the distance to the south is the Hog's Back. This is where the North Downs narrows. It runs between Farnham and Guildford.
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