page_title: River Blackwater (River Loddon)
section_title: Route
hierarchical_section_title: River Blackwater (River Loddon) / Route
caption_attribution_description: English: This photo is of a sign marking the source of the River Blackwater at Rowhill Nature Reserve, Hampshire. The surrounding area is overgrown - the sign being the only marking of where the river begins.
context_page_description: 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. Rowhill Nature Reserve is an isolated remnant of the extensive heathland that once surrounded Farnborough and Aldershot. After 20 miles 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.
context_section_description: The Blackwater rises as a series of springs on Rowhill Copse, a nature reserve to the south-west of Aldershot. The 55-acre (22 ha) site contains a range of habitats, and is on the site of a private estate which once produced timber and bricks. The river heads in a south-easterly direction, passing under the railway line to Aldershot station, between two lakes, under Badshot Lea Road and past some more lakes, which form part of Tice's Meadow nature reserve. This was a hop farm from 1851 until 1958, after which 140 acres (57 ha) were quarried by Hanson Aggregates between 1998 and 2010. The site was adopted as a Site of Nature Conservation Interest (SNCI) in 2009, and was restored after quarrying stopped. Beyond the reserve, the river sweeps round in a large loop to head northwards, and is joined by the A331, which follows the river valley for a considerable distance.
  The Aldershot sewage treatment works is located on the left bank, and during dry weather supplies more than half of the river's flow. Willow Park Fishery is to the east of the river, which passes under an aqueduct carrying the Basingstoke Canal, and is then bordered by Lakeside Nature Reserve to the east and Gold Valley Lakes fishery to the west. The A331 road makes the first of several crossings over the river. Further north is Hollybush Park, a sand quarry which was then used as a landfill site, and is now an attractive grassland with wild flowers. The lakes to the north were the subject of a planning enquiry in 2020, to build 21 floating holiday homes and an equestrian centre. The river is hemmed in by lakes, railways and roads, and is crossed by the railway line to Farnborough station.
  After junction 4 on the M3 motorway, the river is joined by Cove Brook, which starts as a series of streams near Farnborough Airport and flows northwards. For much of its route it is bordered by housing on both sides, but then passes beneath the North Downs railway line to reach the junction. The tree-lined section immediately afterwards was once a gas works and railway sidings, but is now known as Blackwater Park, as far as the A30 road bridge. The small town of Blackwater is on the left bank and Camberley sewage treatment works is on the right bank at York Town. This was the cause of a serious pollution incident in 2012, when a malfunction in the works resulted in partially treated effluent being discharged into the river, and contaminating the river for 1 mile (1.6 km) downstream. This resulted in fish within the Shepherds Meadow SSSI suffocating and dying. Thames Water upgraded part of the works after the incident.   
  To the north of the bridge, the river is joined by the Wish Stream. This rises at Wishmoor Cross, in a danger area with restricted access, and flows to the south west along Wishmoor Bottom, a boggy valley which marks the border between Surrey and Berkshire. It is part of a Site of Special Scientific Interest (SSSI) because of its populations of Dartford warbler, nightjar and woodlark, and is a nationally important habitat for dragonfly and damselfly. The Wish Stream then flows through the grounds of the Royal Military Academy Sandhurst, entering Bathing Pool, and then passing through a series of engineered ponds and weirs, which create a significant obstacle to the movement of fish, to reach the Lower Lake. This is also supplied with water from the Upper Lake, located to the south of the Wish Stream. There is a large control structure at the outlet of the Lower Lake, which is totally impassable to fish, and then a series of high weirs again with no provision for the movement of fish. Below the grounds of the Academy, the stream flows in a culvert under a car park for a retail outlet, and several more culverts under roads to reach the Blackwater. The confluence used to be the point at which the counties of Berkshire, Hampshire and Surrey met, but when the Blackwater Valley road was being constructed in 1990, the Wish Stream was moved a short distance to the north to accommodate the roundabout that links the A30, A321 and A331 roads.
  The river then flows thro
caption: The Source of the River Blackwater at Rowhill Nature Reserve
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