Mid Colne Valley
Encyclopedia
Mid Colne Valley is a 132 hectare biological Site of Special Scientific Interest
at grid reference in Harefield
in the London Borough of Hillingdon
and Denham
in South Buckinghamshire. Its main importance lies in its extensive diversity of birdlife in lakes in former gravel pits.
The site is divided into three areas. The great majority is in an area of four lakes bounded on the west by the River Colne
and on the east by the Grand Union Canal
. The river forms the boundary between Greater London to the east and Buckinghamshire to the west, and west of the river in Denham is a small area called Ranston Covert. The SSSI also includes a field called Coppermill Down east of the canal.
. The lakes were created by dredging for sand and gravel between the 1960s and the 1980s. To the south is Korda Lake, and then to the north of it Harefield Lake next to the Grand Union Canal, with Long Pond adjacent to it by the river. North again is Broadwater Lake, which at 80 hectares occupies over half the entire SSSI. Natural England
regards the condition of the area as 'favourable'.
Korda Lake, Long Pond, the River Colne and the western side of Broadwater Lake form the Broadwater Lake nature reserve, which is managed by the Hertfordshire and Middlesex Wildlife Trust
. Harefield Lake is private land owned by an aggregates company, and silting caused by aggregate washing is a matter of concern to Natural England. The lakes are used for fishing, but this is prohibited between 15 March and 15 June to prevent damage to the SSSI.
Broadwater Lake is unusual in having a number of small islands. It is significant for its breeding wetland birds and over-wintering water birds. Wintering birds which are present in nationally important numbers are great crested grebe
s, cormorants
, shovellers
and tufted ducks
, and the number of gadwalls
is internationally significant. The River Colne is important for bats, particularly daubentons
. The area also has ancient woodland.
There is access from Moorhall Road close to the Colne River bridge.
and the bee orchid
. Its status in September 2011 was described as 'unfavourable declining' due to inadequate grazing. The field is crossed by a footpath between Jacks Lane and Park Lane.
Site of Special Scientific Interest
A Site of Special Scientific Interest is a conservation designation denoting a protected area in the United Kingdom. SSSIs are the basic building block of site-based nature conservation legislation and most other legal nature/geological conservation designations in Great Britain are based upon...
at grid reference in Harefield
Harefield
Harefield is a village in the London Borough of Hillingdon in northwest London, England. It is situated on top of a hill, northwest of Charing Cross, near the Greater London boundary with Buckinghamshire to the west and Hertfordshire to the north...
in the London Borough of Hillingdon
London Borough of Hillingdon
The London Borough of Hillingdon is the westernmost borough in Greater London, England. The borough's population was recorded as 243,006 in the 2001 Census. The borough incorporates the former districts of Ruislip-Northwood, Uxbridge, Hayes and Harlington and Yiewsley and West Drayton in the...
and Denham
Denham, Buckinghamshire
Denham is a village and civil parish in the South Buckinghamshire district of Buckinghamshire, England. It is north west of Uxbridge and north of junction 1 of the M40 motorway. Denham contains the Buckinghamshire Golf Club.-Origin:...
in South Buckinghamshire. Its main importance lies in its extensive diversity of birdlife in lakes in former gravel pits.
The site is divided into three areas. The great majority is in an area of four lakes bounded on the west by the River Colne
River Colne, Hertfordshire
The Colne is a river in England which is a tributary of the River Thames. It flows mainly through Hertfordshire and forms the boundary between the South Bucks district of Buckinghamshire and the London Borough of Hillingdon...
and on the east by the Grand Union Canal
Grand Union Canal
The Grand Union Canal in England is part of the British canal system. Its main line connects London and Birmingham, stretching for 137 miles with 166 locks...
. The river forms the boundary between Greater London to the east and Buckinghamshire to the west, and west of the river in Denham is a small area called Ranston Covert. The SSSI also includes a field called Coppermill Down east of the canal.
Broadwater Lake
The main area of the site is called Broadwater Lake after its principal body of water, and it is part of the Colne Valley regional parkColne Valley regional park
The Colne Valley regional park located to the west of Greater London contains a mixture of farmland, woodland and water, fifty miles of river and canal and over forty lakes. As well as providing homes and farms it is also a regionally important place recreation and internationally important for...
. The lakes were created by dredging for sand and gravel between the 1960s and the 1980s. To the south is Korda Lake, and then to the north of it Harefield Lake next to the Grand Union Canal, with Long Pond adjacent to it by the river. North again is Broadwater Lake, which at 80 hectares occupies over half the entire SSSI. Natural England
Natural England
Natural England is the non-departmental public body of the UK government responsible for ensuring that England's natural environment, including its land, flora and fauna, freshwater and marine environments, geology and soils, are protected and improved...
regards the condition of the area as 'favourable'.
Korda Lake, Long Pond, the River Colne and the western side of Broadwater Lake form the Broadwater Lake nature reserve, which is managed by the Hertfordshire and Middlesex Wildlife Trust
Hertfordshire and Middlesex Wildlife Trust
Hertfordshire and Middlesex Wildlife Trust is a registered charity located in St Albans and is one of the 47 local Wildlife Trusts spread across the whole of the UK....
. Harefield Lake is private land owned by an aggregates company, and silting caused by aggregate washing is a matter of concern to Natural England. The lakes are used for fishing, but this is prohibited between 15 March and 15 June to prevent damage to the SSSI.
Broadwater Lake is unusual in having a number of small islands. It is significant for its breeding wetland birds and over-wintering water birds. Wintering birds which are present in nationally important numbers are great crested grebe
Great Crested Grebe
The Great Crested Grebe is a member of the grebe family of water birds.- Description :The Great Crested Grebe is long with a wingspan. It is an excellent swimmer and diver, and pursues its fish prey underwater. The adults are unmistakable in summer with head and neck decorations...
s, cormorants
Cormorant
The bird family Phalacrocoracidae is represented by some 40 species of cormorants and shags. Several different classifications of the family have been proposed recently, and the number of genera is disputed.- Names :...
, shovellers
Northern Shoveler
The Northern Shoveler , Northern Shoveller in British English, sometimes known simply as the Shoveler, is a common and widespread duck. It breeds in northern areas of Europe and Asia and across most of North America, and is a rare vagrant to Australia...
and tufted ducks
Tufted Duck
The Tufted Duck, Aythya fuligula, is a medium-sized diving duck with a population of close to one million birds.- Description :The adult male is all black except for white flanks and a blue-grey bill. It has an obvious head tuft that gives the species its name.The adult female is brown with paler...
, and the number of gadwalls
Gadwall
The Gadwall is a common and widespread duck of the family Anatidae.- Description :The Gadwall is 46–56 cm long with a 78–90 cm wingspan. The male is slightly larger than the female, weighing on average 990 g against her 850 g...
is internationally significant. The River Colne is important for bats, particularly daubentons
Daubenton's bat
Daubenton's Bat, Myotis daubentonii, is a Eurasian bat with quite short ears. It ranges from Britain to Japan and is considered to be increasing its numbers in many areas.The name commemorates the French naturalist Louis-Jean-Marie Daubenton....
. The area also has ancient woodland.
There is access from Moorhall Road close to the Colne River bridge.
Ranston Covert
Ranston Covert in Denham is the only part of the site in Buckinghamshire. It was formerly a separate SSSI. It is a 26 hectare area of woodland and scrub between the Colne River and Denham Way. It has a variety of breeding birds and its status is described as favourable.Coppermill Down
The SSSI includes a 6 hectare field east of the Grand Union Canal described in the Natural England citation as Coppermill Down, although it is not known by that name locally. It is one of the few remaining examples of unimproved chalk grassland in Greater London, and is notable for the pyramidal orchidPyramidal orchid
The Pyramidal Orchid, Anacamptis pyramidalis, is an herbaceous perennial plant belonging to the Genus Anacamptis of the family Orchidaceae...
and the bee orchid
Bee Orchid
The Bee Orchid is an herbaceous perennial plant belonging to the family Orchidaceae.-Etymology:The name "Ophrys" derives from the Greek word "ophrys", meaning "eyebrow", while the Latin name of the species "apifera" refers to the bee-shaped lip.-Description: The Bee Orchid grows to a height of ....
. Its status in September 2011 was described as 'unfavourable declining' due to inadequate grazing. The field is crossed by a footpath between Jacks Lane and Park Lane.