River Colne, Hertfordshire

Colne
River Colne as it joins the Thames at Staines-upon-Thames
Location
Country	England
Counties	Hertfordshire, Greater London, Buckinghamshire, Surrey, Berkshire
Towns	Watford, Rickmansworth, Uxbridge, West Drayton, Staines-upon-Thames
Physical characteristics
Source	Unnamed brook
• location	east of Bell Bar, Brookmans Park
• coordinates	51°43′50″N 0°10′47″W / 51.7306°N 0.1798°W / 51.7306; -0.1798
• elevation	410 feet (120 m)
2nd source	"Water End" brook
• location	east side of North Mymms Park (coalesence of two streams, liable-to-flood meadow)
Mouth	River Thames
• location	Staines-upon-Thames town centre
• coordinates	51°25′58″N 0°30′55″W / 51.4329°N 0.5152°W / 51.4329; -0.5152
• elevation	48 feet (15 m)
Length	58 kilometres (36 mi)
Discharge
• location	Denham, Buckinghamshire (rate at lower coalescence)
• average	4.05 m3/s (143 cu ft/s)
• minimum	0.74 m3/s (26 cu ft/s)26  August 1976
• maximum	18.4 m3/s (650 cu ft/s)14  October 1993
Discharge
• location	Berrygrove, Berry Grove Lane, Watford (rate at mid-to-upper coalescence)
• average	0.79 m3/s (28 cu ft/s)
Basin features
River system	Thames Basin
Tributaries
• left	Mimmshall Brook, Potters Bar Brook, Tyttenhanger Stream, Tykes Water (The Brook (Radlett)), Hillfield Brook, River Pinn
• right	Ellen Brook and river: Ver, Gade, Chess, Misbourne
Number of distributaries including namesake:	6

v t e River Colne (Hertfordshire)
Legend
Source: two subterranean streams in east of North Mymms Park Colney Heath River Ver Weir Weir Watford — on opposite bank: Oxhey Weir Weir River Gade Grand Union Canal side weir River Chess Rickmansworth (east of)} Batchworth Locks Town Ditch, Rickmansworth  A404  Riverside Drive/Church Street Short navigable branch of river Troy Cut of the Grand Union Canal Railway bridge — Chiltern Main Line Frays River River Misbourne  A40   A4020  Shire Ditch, Uxbridge Park, Denham Uxbridge  A4007  Alder Bourne from Fulmer  M25  Colne Brook  M25  Slough Arm River Pinn Grand Union Canal towards London Great Western Main Line  M25  River Colne  M4  Bigley Ditch  A4  Colnbrook Bypass  M25  Poyle Channel Duke of Northumberland's River Longford River to Hampton Court  A3044  Stanwell Moor  M25  Jn 14 Heathrow Terminal 5 Slip Road  A3044  Stanwell Moor  A3113  Airport Way  M25  Wraysbury River (Staines Moor) Bonehead Ditch Colne Brook Railway bridges — Waterloo to Windsor Line via Staines upon Thames  A30  Staines Bypass River Ash to Sunbury-on-Thames Railway bridge Church Street, Staines-upon-Thames  A308  Clarence Street River Thames

The Colne is a river and a tributary of the River Thames in England. Just over half its course is in south Hertfordshire. Downstream, it forms the boundary between Buckinghamshire and the London Borough of Hillingdon. The confluence with the River Thames is on the Staines reach (above Penton Hook Lock) at Staines-upon-Thames.

Two of its distributaries, constructed in the 1600 – 1750 period largely for aesthetic reasons for Hampton Court and for Syon Park, have been maintained. Their main purpose was not drinking water but these can be likened to the New River in scale and in date. Crossing its route, many viaducts and a canal, the intersecting Grand Union Canal, have been recognised for pioneering engineering during the Industrial Revolution.

Digging for gravel and clay along its lower course near Rickmansworth has created a belt of flooded pits below the water table, as established lakes, many of which are well-adapted habitats for wildlife, protected as nature reserves. The river, meadows and lakes form the Colne Valley regional park covering 43 square miles (110 km²).