| 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″N0°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 ofNorth Mymms Park (coalesence of two streams, liable-to-flood meadow) |
| Mouth | River Thames |
• location | Staines-upon-Thames town centre |
• coordinates | 51°25′58″N0°30′55″W / 51.4329°N 0.5152°W /51.4329; -0.5152 |
• elevation | 48 feet (15 m) |
| Length | 58 km (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 |
River Colne (Hertfordshire) |
|---|
TheColne is ariver and atributary of theRiver Thames inEngland. Just over half its course is in southHertfordshire. Downstream, it forms the boundary betweenBuckinghamshire and theLondon Borough of Hillingdon. Theconfluence with the River Thames is on the Staines reach (abovePenton Hook Lock) atStaines-upon-Thames.
Two of its distributaries, constructed in the 1600 – 1750 period largely for aesthetic reasons forHampton Court and forSyon Park, have been maintained. Their main purpose was not drinking water but these can be likened to theNew River in scale and in date. Crossing its route, many viaducts and a canal, the intersectingGrand Union Canal, have been recognised for pioneering engineering during theIndustrial Revolution.
Digging for gravel and clay along its lower course nearRickmansworth 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 theColne Valley regional park covering 43 square miles (110 km2).
The Colne becomes universally so-named after two closesubterranean streams converge at aspring, or in very wet weather in the meadows above, all along the east side (Tollgate Road) ofNorth Mymms Park inHertfordshire. The source streams are long, multi-source, in final, northern stages, partly underground tributaries: a north-eastern, which can be considered the upper Colne; and theMimmshall Brook. Their main sources are 2.5 to 4 mi (4.0 to 6.4 km): in westernNorthaw,Brookmans Park,Hadley, London andBorehamwood, draining much of those places.[1] A seasonal, intra-parochial stream runs under the seven-building village of North Mymms draining most of the park, which, with adjoining woods is a small square plateau, sloping down to its corners except the south-west.[2][3]
Shallowswallow holes of the two brooks are in North Mymms'Water End, centred on so-named combined surface flow. From theWater End Swallow Holes the Colne runswest, longer NNW, then west then receives the Ellen Brook and turns SSW, then meanders south-west, bounding central and residentialWatford andOxhey, also boundingRickmansworth andBatchworth, then for a similar total stretch boundingGreater London (andSpelthorne), east and (through anabranch ditches)Buckinghamshire, west. Specifically, it passes between West Hyde, nearMaple Cross, andHarefield, passesDenham Green then passesUxbridge, where it parallels theGrand Union Canal and its first main anabranch, theFrays River which is co-fed by thePinn betweenCowley andYiewsley, Greater London. TheColne Brook splits off as adistributary betweenNew Denham and Uxbridge. After this, atWest Drayton, the Frays rejoins and theWraysbury River, the second main anabranch, andDuke of Northumberland's River divide off.
Soon after, atLongford, the intake is given to theLongford River, a 12-mile (19 km) artificial channel created in 1610 forKing Charles I to supply the water features inBushy Park and the rectangular lakes inHampton Court Park.[4]
The Colne'sdrainage basin extends almost as far north again as its northern limit – the inflowingGade,Ver andMisbourne extend well into theChilterns. Opposite, the other2⁄3 of outer west and north-west London is drained by thePymmes Brook,Brent, orCrane sub-basins of the Thames. In the north-west, centred onTring's northern boundary the Chiltern ridge is most noticeable, awatershed of this basin and that of theRiver Great Ouse, north and east towardsthe Wash.
The villages ofColney Heath east ofSt Albans,London Colney south ofSt Albans,Colney Street (almost wholly a large business park) north ofRadlett andColnbrook betweenSlough andHeathrow take their name from the river.Three Rivers District Council covers part ofHertfordshire and is named after the River Colne and its two tributaries, theRiver Chess and theRiver Gade.
Among early proposals to link the river to London was one in 1641 by Sir Edward Forde for a navigable canal, the main purpose of which seems to have been the supply of clean water, and two in 1766, for canals from Marylebone to the river at Uxbridge and another from Marylebone to West Drayton.[5]
The river underwent considerable change in the 1790s, when theGrand Junction Canal (which became part of the Grand Union Canal in 1929) was routed along the valley and still takes the river channel for part of its course. Construction began from Brentford, where it used for 3 miles (4.8 km) the channel of theRiver Brent, and progressed westwards then northwards, with it reaching Uxbridge in November 1794. To reach the Midlands it continued along the river channel until its junction with the River Gade, which it ran parallel to, but did not take over the channel.[6] TheSlough Arm was built in 1882 which required three aqueducts to carry it close to its junction with the Grand Junction, to cross the Fray's River, the River Colne and the Colne Brook.[7]
BetweenCroxley Green, where the River Gade joins the Colne, andThorney/West Drayton, below the Slough Arm, the river channels thread their way between many large lakes, some of which were once watercress beds, some chalk pits,[8] and some of which were the result of brickmaking, an industry that developed over several miles of the valley after 1800, when the Grand Junction Canal company advertised the presence of goodbrick earth, discovered during the construction of the canal.[5]
There are twoLondon Coal Duty markers beside the river, which mark points at which duty became payable on coal entering the London area. The first is on the north side of the river inColney Heath Local Nature Reserve, and is a square-sectioncast iron pillar made by Henry Grissell at hisRegents Canal ironworks and erected in 1861 or 1862. It is 5 feet (1.5 m) high and is painted white.[9] The second is a stone obelisk, 13 feet (4.0 m) high, with a square base, which was erected at Colne Bridge in 1861. It was moved from its original position to the other side of the river in 1984 when it was repaired by Watford Borough Council.[10] It is close to the five-archedColne Viaduct, which was built in 1837 to carry the London to Birmingham Railway over the river. Each of the arches spans around 40 feet (12 m) and is 45 feet (14 m) high. The structure was designed byRobert Stephenson, and isgrade II listed.[11]
At London Colney, there is a seven-arched brick bridge which carries Barnet Road over the river. It dates from 1774 and is called Telford's Bridge, although it is not thought to have been designed byThomas Telford. It was modified in the 20th century when parapets and railings were added.[12]
There was a long-running dispute over water levels in the Batchford area, following the construction of the Grand Junction Canal, which were resolved in 1825, when an 8.2-foot (2.5 m) obelisk was erected in a pond, to act as a water gauge. The obelisk records the agreement made between the canal company,John Dickinson who was the owner ofpapermills at Batchworth, and R. Williams of Moor Park, who was the landowner.[13]
From its mouth to its source, the Colne's named tributaries, anabranches and to-Thames distributaries are:
| Next confluence upstream | River Thames | Next confluence downstream |
| Colne Brook (north) | River Colne | Abbey River (south) |
 Rivers and watercourses ofBuckinghamshire | |
|---|---|
| Non-tributaries | |
| Tributaries | |
| Passing Denham/Iver |
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| Man-made | |
| Main rivers |  | |
|---|---|---|
| Canals and navigations | ||
| Ordinary watercourses | ||
| Lakes, ponds and wetlands |
| |
| Reservoirs | ||
51°25′59″N0°30′55″W / 51.43306°N 0.51528°W /51.43306; -0.51528
