Mid Colne Valley

Mid Colne Valley
Site of Special Scientific Interest
Korda Lake
Area of Search	Greater London Buckinghamshire
Grid reference	TQ043896
Interest	Biological
Area	132.0 hectares
Notification	1985
Location map	Magic Map

Mid Colne Valley is a 132 hectare biological Site of Special Scientific Interest 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.^[1]^[2]

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 park. The lakes were created by dredging for sand and gravel between the 1960s and the 1980s.^[3] 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'.^[4]^[5]

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.^[6] Harefield Lake is private land owned by an aggregates company, and silting caused by aggregate washing is a matter of concern to Natural England.^[5] The lakes are used for fishing, but this is prohibited between 15 March and 15 June to prevent damage to the SSSI.^[7]^[8]

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 grebes, cormorants, shovellers and tufted ducks, and the number of gadwalls is internationally significant. The River Colne is important for bats, particularly Daubentons.^[6] The area also has ancient woodland.^[9]

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.^[2] 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.^[10]

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 orchid and the bee orchid.^[2] Its status in September 2011 was described as 'unfavourable declining' due to inadequate grazing.^[11] The field is crossed by a footpath between Jacks Lane and Park Lane.^[12]

High Speed 2

Proposed high speed railway High Speed 2 between, initially, London and the Midlands if built will cut across a corner of the site on a viaduct. Natural England commented that there would be a serious loss of ancient woodland and a potentially damaging indirect impact on Broadwater Lake.^[9]

Wikimedia Commons has media related to Mid Colne Valley.

References

Sites of Special Scientific Interest in Greater London

Biological	Barn Elms Wetland Centre Bentley Priory Brent Reservoir Bushy Park Chingford Reservoirs Crofton Woods Croham Hurst Denham Lock Wood Downe Bank Epping Forest Farthing Downs Frays Farm Meadows Hainault Forest Hampstead Heath Woods Happy Valley Hayes Common High Elms Home Park Ingrebourne Marshes Inner Thames Marshes Kempton Park Reservoirs Keston Common Mid Colne Valley Old Park Wood Oxleas Woodlands Richmond Park Riddlesdown Ruislip Woods Ruxley Gravel Pits Saltbox Hill Syon Park Walthamstow Marshes Walthamstow Reservoirs Wimbledon Common

Geological	Abbey Wood Elmstead Pit Gilbert's Pit Harefield Pit Harrow Weald Hornchurch Cutting Wansunt Pit

Sites of Special Scientific Interest in Buckinghamshire-

Biological	Ashridge Commons and Woods Aston Clinton Ragpits Aston Rowant Aston Rowant Woods Bacombe and Coombe Hills Black Park Bradenham Woods, Park Wood and The Coppice Burnham Beeches Buttler's Hangings Dancersend Dancersend Waterworks Ellesborough and Kimble Warrens Fayland Chalk Bank Finemere Wood Foxcote Reservoir and Wood Frieth Meadows Frogmore Meadows Gomm Valley Grangelands and Pulpit Hill Grendon and Doddershall Woods Ham Home-cum-hamgreen Woods Hodgemoor Wood Hollowhill and Pullingshill Woods Homefield Wood Howe Park Wood Ivinghoe Hills Kingcup Meadows and Oldhouse Wood Kings and Bakers Woods and Heaths Littleworth Common Lodge Hill Long Herdon Meadow Mid Colne Valley Millfield Wood Moorend Common Naphill Common Old Rectory Meadows Oxley Mead Pilch Fields Pitstone Hill Poker's Pond Meadow Rodbed Wood Rushbeds Wood and Railway Cutting Shabbington Woods Complex Sheephouse Wood Stoke Common Swain's Wood Temple Island Meadows Tingewick Meadows Tring Reservoirs Turville Hill Weston Turville Reservoir Widdenton Park Wood Windsor Hill Wormsley Chalk Banks Yardley Chase

Geological	Bierton Clay Pit Bolter End Sand Pit Bugle Quarry Fern House Gravel Pit Froghall Brickworks Muswell Hill Pitstone Quarry South Lodge Pit Stone Warren Farm, Stewkley

Herts and Middlesex Wildlife Trust

Nature reserves	Aldbury Nowers Alpine Meadow Amwell Quarry Balls Wood Blagrove Common Broadwater Lake Cassiobury Park Danemead Fox Covert Frogmore Meadow Hertford Heath Hunsdon and Eastwick Meads Old Park Wood Patmore Heath Pryor's Wood Rye Meads Stanborough Reedmarsh Stocker's Lake Tewinbury Thorley Wash Tring Reservoirs Uxbridge Alderglade Waterford Heath

Coordinates: 51°35′35″N 0°29′38″W / 51.593°N 0.494°W / 51.593; -0.494