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57-558: Darwin College Bridges are the fourth and fifth river Cam bridges overall and two first bridges on its middle stream in Cambridge . Bridges made of timber connect the college grounds with the college's two islands. This article about a bridge in the United Kingdom is a stub . You can help Misplaced Pages by expanding it . River Cam The River Cam ( / ˈ k æ m / )

114-414: A maximum of eleven, had powers to mortgage the tolls, in order to raise capital for improvements to the river immediately. This they did, and built sluices at Jesus Green, Chesterton, Baits Bite and Clayhithe. Most of the tolls were collected at Clayhithe. Prior to 1722, Denver sluice had been destroyed, and although Cambridge Corporation opposed its reconstruction, it was rebuilt by 1750. The river entered

171-482: A negative effect on fish species that migrate as part of their breeding cycle (e.g., salmonids ), but it also can be useful as a method of preventing invasive species moving upstream. For example, weirs in the Great Lakes region have helped to prevent invasive sea lamprey from colonising farther upstream. Mill ponds are created by a weir that impounds water that then flows over the structure. The energy created by

228-485: A period of steady profitability, with toll receipts rising from £432 in 1752 to over £1,000 by 1803. In 1835 they peaked at £1,995, and then declined slightly until 1846. The Convervators also raised some revenue from rents on the public houses which they owned adjacent to each of the sluices. Another Act of Parliament was obtained on 21 July 1813 which allowed the Conservators to alter the tolls and charge penalties, while

285-617: A person to operate them. The colleges and at least one private operator also own punts which are available for members of the public to travel on. Canoeing and kayaking , both recreational and competitive, are popular at all times of year, especially on the section above the Mill Pond towards Grantchester. Both Cambridge Canoe Club (on Sheep's Green ) and Cambridge University Canoe Club (just upstream from Newnham ) are based here. Powered boats may navigate as far upstream as La Mimosa restaurant (next to Jesus Green) all year round, and as far as

342-415: A range of biota , including poor swimmers. Even though the water around weirs can often appear relatively calm, they can be extremely dangerous places to boat, swim, or wade, as the circulation patterns on the downstream side—typically called a hydraulic jump —can submerge a person indefinitely. This phenomenon is so well known to canoeists, kayakers, and others who spend time on rivers that they even have

399-416: A rueful name for weirs: "drowning machines". The Ohio DNR recommends that a victim should "tuck the chin down, draw the knees up to the chest with arms wrapped around them. Hopefully, conditions will be such that the current will push the victim along the bed of the river until swept beyond the boil line and released by the hydraulic." The Pennsylvania State Police also recommends to victims, "curl up, dive to

456-773: A slipway from lower to upper level. From the Mill Pool and its weir, the river can be followed upstream through Grantchester meadows to the village of Grantchester and Byron's Pool, where it is fed by many streams. The two principal tributaries of the Cam are the Granta and the Rhee , though both are also known as the Cam. The Rhee begins just off the High Street ( Ashwell Springs ), at Ashwell in Hertfordshire . Running north out of Ashwell, it forms

513-449: A weir is broad-crested for much of its length, but has a section where the weir stops or is 'open' so that small boats and fish can traverse the structure. A notch weir is any weir where the physical barrier is significantly higher than the water level except for a specific notch (often V-shaped) cut into the panel. At times of normal flow all the water must pass through the notch, simplifying flow volume calculations, and at times of flood

570-405: Is a flat-crested structure, where the water passes over a crest that covers much or all of the channel width. This is one of the most common types of weir found worldwide. A compound weir is any weir that comprises several different designs into one structure. They are commonly seen in locations where a river has multiple users who may need to bypass the structure. A common design would be one where

627-473: Is a generic relationship and specific calculations are available for the many different types of weir. Flow measurement weirs must be well maintained if they are to remain accurate. The flow over a V-notch weir (in ft /s) is given by the Kindsvater–Shen equation: where As weirs are a physical barrier, they can impede the longitudinal movement of fish and other animals up and down a river. This can have

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684-696: Is extant and the foundations of the mill can be seen when the water is low. Byron's Pool is named after the poet, Lord Byron , who is reputed to have swum there. It was certainly a bathing place for Rupert Brooke and the Cambridge neo-Pagans . Brooke used to canoe from Cambridge to lodgings in Grantchester, which included the Old Vicarage . His homesick poem of 1912 evokes the river: —" The Old Vicarage, Grantchester ", Collected Poems (1916) One of Brooke's contemporaries, Gwen Darwin , later Raverat, grew up in

741-624: Is not murky and is clean enough from its source to its confluence with the Great Ouse to support fish. The fishing rights on the west bank are leased annually to the Cambridge Fish Preservation and Angling Society. The Cam below Bottisham Sluice may still hold burbot , a fish thought to be extinct in English waters since the early 1970s. The last known burbot caught in Britain was in 1969, on

798-524: Is sometimes called the lower river. The stretch between Jesus Lock and Baits Bite Lock is much used for rowing . There are also many residential boats on this stretch, their occupants forming a community who call themselves the Camboaters. Navigation on the lowest section of the Cam, below and including Bottisham Lock, is the responsibility of the Environment Agency . The stretch above Jesus Lock

855-465: Is sometimes known as the middle river (with the section above the Mill Pond being referred to as the upper river). Between Jesus Lock and the Mill Pond, it passes through the Backs below the walls of many of the colleges . This is the section of river most popular with tourists, with its picture-postcard views of elegant bridges, green lawns and graceful willows. This stretch also has the unusual feature of

912-554: Is the main river flowing through Cambridge in eastern England . After leaving Cambridge, it flows north and east before joining the River Great Ouse to the south of Ely , at Pope's Corner. The total distance from Cambridge to the sea is about 40 mi (64 km) and is navigable for punts, small boats, and rowing craft. The Great Ouse also connects to England's canal system via the Middle Level Navigations and

969-619: The River Nene . In total, the Cam runs for around 69 kilometres (43 mi) from its furthest source (near Debden in Essex ) to its confluence with the Great Ouse. The original name of the river was the Granta and (unusually) its present name derives from the city of Cambridge ( Old English : Grantebrycge ) rather than the other way around: After the city's present name developed in Middle English ,

1026-632: The Association in 1643 regulated use of the river for trade, but the biggest change was the construction of Denver Sluice on the River Great Ouse, which reduced river levels on the lower river as tidal waters were excluded from the Ouse. Both the university and the Corporation of Cambridge complained to Parliament in 1697 that the trade route to the town from King's Lynn had been severely impaired. In 1699,

1083-410: The Cam at Byron's Pool. " The Reeve's Tale " from Geoffrey Chaucer 's Canterbury Tales begins: At Trumpyngtoun, nat fer fro Cantebrigge, Ther gooth a brook, and over that a brigge, Upon the whiche brook ther stant a melle; And this is verray sooth that I yow telle: A millere was ther dwellynge many a day. The mill formerly stood by Brasley Bridge on Grantchester Road. The mill pond

1140-618: The Cam, and in 2010 a fisherman reported spotting two in the Great Ouse. Above Hinxton and Great Chesterford the river holds a stock of wild brown trout, though it is also stocked by the Audley Fly Fishers club and other angling societies who own the rights. All boats require a navigation licence from either the Conservators of the River Cam or the Environment Agency. There are public moorings just below Jesus Lock on both sides of

1197-653: The City Council for holders of its long-term mooring permits. There are also some privately owned moorings. There is a public slipway next to the garden of the Green Dragon pub in Water Street, Chesterton . This is occasionally used for launching small boats. Punting is the most popular form of boating on the stretch of the river between Jesus Lock and Grantchester. Several of the colleges own punts, and they can also be hired from various companies, either with or without

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1254-439: The Corporation sought to obtain an Act of Parliament which would allow them to improve the river from Clayhithe to Queens Mill at Cambridge. This was obtained on 27 February 1702 and created the Conservators of the River Cam, a legal body with authority to charge tolls for use of the river, which ranged from four shillings (20p) a ton for wine to one penny (0.4p) per person for passengers. The Conservators, of which there were

1311-677: The Granta. On Ordnance Survey maps, the two main tributaries' alternative names are recognised: "River Cam or Granta" and "River Cam or Rhee". The Cam has no connection with the much smaller River Cam in Gloucestershire . An organisation called the Conservators of the River Cam was formed in 1702, charged with keeping the river navigable. The Conservators are responsible for the two locks in and north east of Cambridge: Jesus Lock and Baits Bite Lock. The stretch north (downstream) of Jesus Lock

1368-589: The Mill Pool between 1 October and 31 March. The lower river between Jesus Lock and Baits Bite Lock is the training and racing home of the Cambridge University Combined Boat Clubs ' university and college, and the Cambridgeshire Rowing Association 's town, rowing teams. The Cambridge Lent , May and Town Bumps rowing races, where boats set off at regular intervals, and the object is to catch and touch (that is, 'bump')

1425-550: The Rhee a mile south of Grantchester at Hauxton Junction. From source to its confluence with the Rhee it is 41.7 kilometres (25.9 mi) in length. A further tributary, also known as the Granta, runs 10 mi (16 km) from south of Haverhill to join the larger Granta south of Great Shelford . Another minor tributary is Bourn Brook which has its source near the village of Eltisley , 10 mi (16 km) west of Cambridge, running east through Caxton , Bourn and Toft to join

1482-467: The River Cam prior to the draining of the Fens . As the university colleges rose in importance, the course of the river through the town, known as the Backs, was moved further to the east to accommodate their new buildings. A report conducted in 1618 by Richard Atkyns highlighted the problems caused by sandbanks above Clayhithe and watermills obstructing navigation. An order made by the parliamentary Committee of

1539-514: The River Cam. The Cam is normally a placid river but flooding does occasionally happen. The most recent serious floods were in 2001, first in February and again on 22–23 October, and then in February 2009. The Environment Agency is responsible for managing water levels and issuing flood warnings for the entire river. Download coordinates as: Weir Weir can also refer to the skimmer found in most in-ground swimming pools, which controls

1596-480: The Roman Ermine Street , it crosses the avenue of Wimpole Hall and a few kilometres later it receives the waters of the minor River Mel that runs through Meldreth . It runs along the southern edge of the village of Barrington, where it still powers a water mill known as Bulbeck Mill. At Harston it passes Harston Mill, the site of a water mill from at least the 11th century until the need for mill died out in

1653-466: The South Level Act of 1827 created Commissioners who had responsibility for the river below Bottisham . This act also appointed the vice-chancellor of the university and the mayor as navigation commissioners. The Conservators built locks at Baits Bite and Bottisham, and removed the sluice at Chesterton. The river was sufficiently profitable that the Conservators were able to contribute £400 towards

1710-469: The boat in front, are held here. The Cam Sailing Club was founded in 1899. It is based at Clayhithe near Waterbeach and organises sailing races most weekends between March and November. Swimming on the upper river is popular in the summer, and people bathe at Grantchester Meadows all year round. Hardy bathers take part in the New Year's Day swim. Cambridge had been an inland port due to its location on

1767-502: The bottom, and swim or crawl downstream". As the hydraulic jump entrains air, the buoyancy of the water between the dam and boil line will be reduced by upward of 30%, and if a victim is unable to float, escape at the base of the dam may be the only option for survival. There are many different types of weirs and they can vary from a simple stone structure that is barely noticeable, to elaborate and very large structures that require extensive management and maintenance. A broad-crested weir

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1824-501: The change in height of the water can then be used to power waterwheels and power sawmills, grinding wheels, and other equipment. Weirs are commonly used to control the flow rates of rivers during periods of high discharge. Sluice gates (or in some cases the height of the weir crest) can be altered to increase or decrease the volume of water flowing downstream. Weirs for this purpose are commonly found upstream of towns and villages and can either be automated or manually operated. By slowing

1881-754: The cost of rebuilding the Great Bridge, now called the Magdalene Bridge , in 1823, and a further £300 for the rebuilding of the Small Bridge, now Silver Street Bridge, in 1841. A year later they constructed a house at Clayhithe, which cost £880, and included a large room for meetings and banquets. Just three years later the Eastern Counties Railway reached Cambridge, and the navigation declined rapidly. Receipts dropped from £1,393 in 1846 to £367 in 1850, and were just £99 in 1898. Most commercial carrying on

1938-462: The county boundary between Bedfordshire and Hertfordshire for around two kilometres, then the boundary between Bedfordshire and Cambridgeshire for a further kilometre. At this point its course turns east and from here until it merges with the Granta it forms the parish boundary between a succession of villages, though until it reaches Barrington it remains at a distance of around a kilometre from any settlement of any size. Just after flowing under

1995-505: The crest of an overflow spillway on a large dam may therefore be referred to as a weir. Weirs can vary in size both horizontally and vertically, with the smallest being only a few centimetres in height whilst the largest may be many metres tall and hundreds of metres long. Some common weir purposes are outlined below. Weirs allow hydrologists and engineers a simple method of measuring the volumetric flow rate in small to medium-sized streams/rivers or in industrial discharge locations. Since

2052-414: The design of a weir that ensure that fish can bypass the barriers and access upstream habitats. Unlike dams, weirs do not usually prevent downstream fish migration (as water flows over the top and allows fish to bypass the structure in that water), although they can create flow conditions that injure juvenile fish. Recent studies suggest that navigation locks have also potential to provide increased access for

2109-420: The downstream end. Jesus lock is manually operated, and has mitre gates at both ends. Boat sizes are restricted to 96.8 ft (29.5 m) by the length of Bottisham lock, and to 14 ft (4.3 m) by the width of Baits Bite lock. Jesus lock is only 9.7 ft (3.0 m) wide. The navigable lodes of Reach , Swaffham Bulbeck and Bottisham, the last of which is no longer navigable, can be reached from

2166-408: The flat-bottomed punts . Between 1 October and 31 March powered boats are allowed as far as Mill Pool, but few people take advantage of this, as there are very few public mooring places along the Backs, and the river is too narrow and the bridges too low to afford easy passing or turning for many boats. Punts and canoes can be manhandled around the weir above the Mill Pool by means of the rollers,

2223-413: The flow of water pulled into the filtering system. The word likely originated from Middle English were , Old English wer , a derivative of the root of the verb werian, meaning "to defend, dam". The German cognate is Wehr , which means the same as English weir. Commonly, weirs are used to prevent flooding , measure water discharge, and help render rivers more navigable by boat. In some locations,

2280-461: The front of Audley End House , and is also joined by the stream known as Fulfen Slade. It then skirts the edges of a number of villages as it moves into Cambridgeshire, successively Littlebury , Little Chesterford , Great Chesterford , Ickleton , Hinxton , Duxford and Whittlesford , powering a number of water mills along the way. Forming the boundary between Great Shelford and Little Shelford , it turns west to flow past Hauxton to merge with

2337-602: The geometry of the top of the weir is known and all water flows over the weir, the depth of water behind the weir can be converted to a rate of flow. However, this can only be achieved in locations where all water flows over the top of the weir crest (as opposed to around the sides or through conduits or sluices) and at locations where the water that flows over the crest is carried away from the structure. If these conditions are not met, it can make flow measurement complicated, inaccurate, or even impossible. The discharge calculation can be summarised as where However, this calculation

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2394-476: The hills of Uttlesford , it turns north just west of the village of Henham . From there until Great Shelford it largely follows the course of the West Anglia Main Line railway. Its northward journey passes first through Newport , where it is joined by the streams known as Wicken Water and Debden Water. A couple of miles later it forms a picturesque addition to views of the stately home as it flows past

2451-436: The house at Clayhithe is now the residence of the foreman of the Conservators. The Conservators are still responsible for the river above Bottisham lock, while the lower river has been managed by the Environment Agency since its creation in 1995. The three locks are all of different sizes. Bottisham and Baits Bite locks are both fully automated, with a vertical guillotine gate at the upstream end and traditional mitre gates at

2508-423: The maximum height a species can jump or creates flow conditions that cannot be bypassed (e.g., due to excessive water velocity) effectively limits the maximum point upstream that fish can migrate. In some cases this can mean that huge lengths of breeding habitat are lost, and over time this can have a significant impact on fish populations. In many countries, it is now a legal requirement to build fish ladders into

2565-440: The mid-20th century, and the parish church of All Saints. It then touches the eastern edge of the village of Haslingfield before joining the Granta at Hauxton Junction. From source to its confluence with the Granta it is 33.2 kilometres (20.6 mi) in length. The longer tributary, the Granta, starts in the parish of Debden to the east of the village of Widdington in Essex . After initially running south west to descend from

2622-747: The old mill by the Mill Pond. Her book, Period Piece , is a memoir of a childhood messing about on the river. The mill house is now part of Darwin College . Children's author Philippa Pearce , who lived in Great Shelford until her death in December 2006, featured the Cam in her books, most notably Minnow on the Say . The river is renamed the River Say, with Great and Little Shelford becoming Great and Little Barley, and Cambridge becoming "Castleford" (not to be confused with

2679-413: The rate at which water moves downstream even slightly, a disproportionate effect can be had on the likelihood of flooding. On larger rivers, a weir can also alter the flow characteristics of the waterway to the point that vessels are able to navigate areas previously inaccessible due to extreme currents or eddies . Many larger weirs will have construction features that allow boats and river users to "shoot

2736-479: The real town of the same name in West Yorkshire). River Cam is referred to as "Camus, reverend Sire" in line 103 of John Milton 's pastoral elegy Lycidas . Edward King , in whose memory the elegy was composed, was a fellow student at Cambridge. Like many rivers, the Cam is extensively used for several forms of recreational activity. These include angling, swimming and various kinds of boating. The water

2793-435: The remains of a submerged towpath : the riverside colleges did not permit barge horses on the Backs, so the beasts waded up the Cam to the mill pulling their loads behind them. Access for mechanically powered boats is prohibited above 'La Mimosa' Pub (at the upstream end of Jesus Green ) between 1 April and 30 September, when the middle and upper river are open only to manually propelled craft. The most common of these are

2850-494: The river and on the western bank just north of the bridge at Clayhithe (both with a maximum stay of 48 hours), and unofficial moorings on the railings adjoining Riverside in Cambridge (unlimited stay, but usually fully occupied) which are under review by Cambridge City Council and likely to be reduced to eight or nine formalised residential moorings, or removed altogether. The moorings on the commons in Cambridge (Jesus Green, Midsummer Common and Stourbridge Common) are reserved by

2907-427: The river bottom) that reduces the water oxygen content and smothers invertebrate habitat and fish spawning sites. The oxygen content typically returns to normal once water has passed over the weir crest (although it can be hyper-oxygenated), although increased river velocity can scour the river bed causing erosion and habitat loss. Weirs can have a significant effect on fish migration . Any weir that exceeds either

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2964-409: The river had stopped by World War I , although Banhams operated two steam tugs and three barges until the late 1930s, carrying gas water from Cambridge Gasworks to King's Lynn, where it was used in the manufacture of fertiliser. The last recorded passenger services had ceased nearly 100 years earlier, in 1839 and were started again in 2008 with the passenger vessel moored on Jesus Green. Traffic using

3021-454: The river today consists of private cruisers making the journey to Jesus Lock, with the section above Baits Bite lock regularly in use by the University rowing clubs, both for practice and for races. Motorised craft can navigate along the Backs in winter, but headroom is severely restricted. The Conservators of the River Cam now have an office in the former lock-keepers cottage at Baits Bite, while

3078-529: The river's name was backformed to match. This was not universally applied, however, and the upper stretch of the river continues to be informally known as the Granta . It has been said that the river is the "Granta" above the Silver Street Bridge (in Cambridge) and the "Cam" below it. The Rhee tributary is also formally known as the Cam, and the Granta has a tributary on its upper stretch also known as

3135-410: The terms dam and weir are synonymous, but normally there is a clear distinction made between the structures. Usually, a dam is designed specifically to impound water behind a wall, whilst a weir is designed to alter the river flow characteristics. A common distinction between dams and weirs is that water flows over the top (crest) of a weir or underneath it for at least some of its length. Accordingly,

3192-515: The water level can rise and submerge the weir without any alterations made to the structure. A polynomial weir is a weir that has a geometry defined by a polynomial equation of any order n . In practice, most weirs are low-order polynomial weirs. The standard rectangular weir is, for example, a polynomial weir of order zero. The triangular (V-notch) and trapezoidal weirs are of order one. High-order polynomial weirs are providing wider range of Head-Discharge relationships, and hence better control of

3249-540: The weir" and navigate by passing up or down stream without having to exit the river. Weirs constructed for this purpose are especially common on the River Thames , and most are situated near each of the river's 45 locks . Because a weir impounds water behind it and alters the flow regime of the river, it can have an effect on the local ecology . Typically, the reduced river velocity upstream can lead to increased siltation (deposition of fine particles of silt and clay on

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