Chalk streams are rivers that rise from springs in landscapes with

chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Ch ...

bedrock In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface material. An exposed portion of bed ...

. Since chalk is permeable, water easily percolates through the ground to the

water table The water table is the upper surface of the phreatic zone or zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with groundwater, which may be fresh, saline, or brackish, depending on the loc ...

and chalk streams therefore receive little

surface runoff Surface runoff (also known as overland flow or terrestrial runoff) is the unconfined flow of water over the ground surface, in contrast to ''channel runoff'' (or ''stream flow''). It occurs when excess rainwater, stormwater, meltwater, or other ...

. As a result, the water in the streams contains little

organic matter Organic matter, organic material or natural organic matter is the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have come fro ...

and

sediment Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

and is generally very clear. The beds of the rivers are generally composed of clean, compacted

gravel Gravel () is a loose aggregation of rock fragments. Gravel occurs naturally on Earth as a result of sedimentation, sedimentary and erosion, erosive geological processes; it is also produced in large quantities commercially as crushed stone. Gr ...

and

flint Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, categorized as the variety of chert that occurs in chalk or marly limestone. Historically, flint was widely used to make stone tools and start ...

s, which provide good spawning grounds for

Salmonidae Salmonidae (, ) is a family (biology), family of ray-finned fish, the only extant member of the suborder Salmonoidei, consisting of 11 extant genera and over 200 species collectively known as "salmonids" or "salmonoids". The family includes salmo ...

fish species. Since they are primarily fed by

aquifer An aquifer is an underground layer of water-bearing material, consisting of permeability (Earth sciences), permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The s ...

s, the flow rate, mineral content and temperature range of chalk streams shows less seasonal variation than other rivers. They are mildly

alkali In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The a ...

ne and contain high levels of

nitrate Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in wa ...

phosphate Phosphates are the naturally occurring form of the element phosphorus. In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthop ...

potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...

and

silicate A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used ...

. In addition to

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

and

diatom A diatom (Neo-Latin ''diatoma'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's B ...

s, the streams provide a suitable habitat for macrophytes (including water crowfoot) and oxygen levels are generally supportive of coarse fish populations. Of the 210 rivers classified as chalk streams globally, 160 are in England. A list of chalk streams in England gives a total of 224.

Geology and hydrology

Chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Ch ...

is a highly

porous Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure ...

and permeable rock, and

rain Rain is a form of precipitation where water drop (liquid), droplets that have condensation, condensed from Water vapor#In Earth's atmosphere, atmospheric water vapor fall under gravity. Rain is a major component of the water cycle and is res ...

falling onto chalk topography percolates directly into the ground, where the chalk layer acts as an

. The

groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...

flows through the chalk bedrock and reappears lower down the slope in springs. The chalk acts as a temporary

reservoir A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation. Reservoirs are created by controlling a watercourse that drains an existing body of wa ...

by regulating the amount of water supplied to the springs. As a result, many chalk streams in the UK have stable flow regimes that vary only slightly over time. The temperature of the emerging surface water is fairly stable, rarely deviating from . On cold winter mornings, water vapour from the relatively warm stream condenses in the cold air above to form fog. Chalk is slightly soluble in

water because rain is naturally slightly

acidic An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen cation, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid. The first category of acids are the ...

. The products of chalk

weathering Weathering is the deterioration of rocks, soils and minerals (as well as wood and artificial materials) through contact with water, atmospheric gases, sunlight, and biological organisms. It occurs '' in situ'' (on-site, with little or no move ...

are dissolved in rainwater and are transported in streams. Chalk streams transport little suspended material (unlike most rivers), but are considered "

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

-rich" due to the dissolved calcium and

carbonate A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group ...

ions. The surface water of chalk streams is commonly described as "gin clear". The channel bed consists of angular

derived from the natural flint deposits found embedded within the chalk geology that contains relatively low amounts of clay and silt deposits. The unique characteristics of chalk stream ecology are due to stable temperature and flow regimes combined with highly transparent water and lack of

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

grade sediment particles.

Ecology

The chalk streams have been intensively managed for many generations. In the 20th and 21st centuries, much of that management has been aimed at producing the best conditions for

fly fishing Fly fishing is an angling technique that uses an ultra-lightweight lure called an artificial fly, which typically mimics small invertebrates such as flying and aquatic insects to attract and catch fish. Because the mass of the fly lure is in ...

, and in particular dry fly fishing. The chalk streams hold a good number of wild salmonid fish species such as the

brown trout The brown trout (''Salmo trutta'') is a species of salmonid ray-finned fish and the most widely distributed species of the genus ''Salmo'', endemic to most of Europe, West Asia and parts of North Africa, and has been widely introduced globally ...

(''Salmo trutta''), and grayling (''Thymallus thymallus''). In addition to these there are also considerable numbers of stocked brown trout and stocked

rainbow trout The rainbow trout (''Oncorhynchus mykiss'') is a species of trout native to cold-water tributary, tributaries of the Pacific Ocean in North America and Asia. The steelhead (sometimes called steelhead trout) is an Fish migration#Classification, ...

(''Oncorhynchus mykiss''). The rich

invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

life and characteristically clear, shallow waters make chalk rivers and streams particularly suitable for fly fishing. Many of the chalk stream springs are also used as sites for

watercress Watercress or yellowcress (''Nasturtium officinale'') is a species of aquatic flowering plant in the cabbage family, Brassicaceae. Watercress is a rapidly growing perennial plant native to Eurasia. It is one of the oldest known leaf vegetabl ...

production, due to the constant temperature and clean,

alkaline In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The ...

, mineral-rich spring water. The

Mid Hants Watercress Railway The Watercress Line is the marketing name of the Mid-Hants Railway, a heritage railway in Hampshire, England, running from New Alresford to Alton, Hampshire, Alton where it connects to the National Rail network. The line gained its popular ...

Hampshire Hampshire (, ; abbreviated to Hants.) is a Ceremonial counties of England, ceremonial county in South East England. It is bordered by Berkshire to the north, Surrey and West Sussex to the east, the Isle of Wight across the Solent to the south, ...

is so named on account of its use for transporting watercress to London from local chalk streams. A number of the chalk aquifers and associated groundwater sources related to chalk streams and rivers are used for

water abstraction Water extraction (also known as water withdrawal, water abstraction, and water intake) is the process of taking water from any source, either temporarily or permanently, for flood control or to obtain water for, for example, irrigation. The ex ...

by local and national water utility companies.

Chalk stream decline

Excessive abstraction of chalk streams by private water companies in the UK has led to the drying up of chalk streams. This has caused ecological damage, stagnant sewage flowing through the rivers and rising phosphate levels.

Chalk streams of England

Terminology

Although chalk streams are generally defined as watercourses originating in chalk hills, including winterbournes, streams, and rivers, the term ''chalk stream'' is also used for larger rivers that would normally be considered too large for the term ''stream''. The Somme in northern France is a chalk stream on a larger scale. Winterbournes are known by different names depending on region: * ''Winterbourne'' –

Wiltshire Wiltshire (; abbreviated to Wilts) is a ceremonial county in South West England. It borders Gloucestershire to the north, Oxfordshire to the north-east, Berkshire to the east, Hampshire to the south-east, Dorset to the south, and Somerset to ...

and

Dorset Dorset ( ; Archaism, archaically: Dorsetshire , ) is a Ceremonial counties of England, ceremonial county in South West England. It is bordered by Somerset to the north-west, Wiltshire to the north and the north-east, Hampshire to the east, t ...

. * ''Nailbourne'' –

Kent Kent is a Ceremonial counties of England, ceremonial county in South East England. It is bordered by Essex across the Thames Estuary to the north, the Strait of Dover to the south-east, East Sussex to the south-west, Surrey to the west, and Gr ...

. * ''Lavant'' –

. * ''Gypsey'' –

Yorkshire Wolds The Yorkshire Wolds are hills in the counties of the East Riding of Yorkshire and North Yorkshire in Northern England. They are the northernmost chalk hills in the UK and within lies the northernmost chalk stream in Europe, the Gypsey Race. ...

Regions (England)

List (England)

Southern England

Chalk streams of the Southern England Chalk Formation in

Berkshire Berkshire ( ; abbreviated ), officially the Royal County of Berkshire, is a Ceremonial counties of England, ceremonial county in South East England. It is bordered by Oxfordshire to the north, Buckinghamshire to the north-east, Greater London ...

and the

Isle of Wight The Isle of Wight (Help:IPA/English, /waɪt/ Help:Pronunciation respelling key, ''WYTE'') is an island off the south coast of England which, together with its surrounding uninhabited islets and Skerry, skerries, is also a ceremonial county. T ...

: *

River Avon, Hampshire The River Avon ( ) is in the south of England, rising in Wiltshire, flowing through that county's city of Salisbury and then west Hampshire, before reaching the English Channel through Christchurch Harbour in the Bournemouth, Christchurch and ...

and its tributaries including the ** River Bourne ** River Ebble ** River Nadder **

River Wylye The River Wylye ( ), also known in its upper reaches as the River Deverill, is a chalk stream in Wiltshire, England, with clear water flowing over gravel. It is popular with fly fishermen. A half-mile stretch of the river and three lakes in W ...

* River Frome * River Itchen and its small tributaries *

River Kennet The Kennet is a tributary of the River Thames in Southern England. Most of the river is straddled by the North Wessex Downs AONB (Area of Outstanding Natural Beauty). The lower reaches have been made navigable as the Kennet Navigation, which � ...

* River Lambourn *River Loddon * Letcombe Brook * River Meon *

River Piddle The River Piddle or Trent or North River is a small rural Dorset river which rises in the Dorset Downs and flows into Poole Harbour near Wareham. Etymology The river's name has Germanic origins and has had various spellings over the years. I ...

River Test The River Test is a chalk stream in Hampshire in the south of England. It rises at Ashe near Basingstoke and flows southwards for to Southampton Water. Settlements on the Test include the towns of Stockbridge and Romsey. The river's vall ...

and its tributaries * River Caul Bourne Chalk streams of the Southern England Chalk Formation in the

Chiltern Hills The Chiltern Hills or the Chilterns are a chalk escarpment in southern England, located to the north-west of London, covering across Oxfordshire, Buckinghamshire, Hertfordshire and Bedfordshire; they stretch from Goring-on-Thames in the south- ...

Hertfordshire Hertfordshire ( or ; often abbreviated Herts) is a ceremonial county in the East of England and one of the home counties. It borders Bedfordshire to the north-west, Cambridgeshire to the north-east, Essex to the east, Greater London to the ...

and

Surrey Surrey () is a Ceremonial counties of England, ceremonial county in South East England. It is bordered by Greater London to the northeast, Kent to the east, East Sussex, East and West Sussex to the south, and Hampshire and Berkshire to the wes ...

(tributaries of the

River Thames The River Thames ( ), known alternatively in parts as the The Isis, River Isis, is a river that flows through southern England including London. At , it is the longest river entirely in England and the Longest rivers of the United Kingdom, s ...

River Lea The River Lea ( ) is in the East of England and Greater London. It originates in Bedfordshire, in the Chiltern Hills, and flows southeast through Hertfordshire, along the Essex border and into Greater London, to meet the River Thames at Bow Cr ...

and River Colne): * River Ash * Barton Springs *

River Beane The River Beane is a short river in the county of Hertfordshire, England. A tributary of the River Lea, it rises to the south-west of Sandon, Hertfordshire, Sandon in the hills northeast of Stevenage and joins the Lea at Hartham Common in Hert ...

* River Bulbourne *

River Chess The River Chess is a chalk stream that rises near Chesham in the Chiltern Hills in England, and flows for through Buckinghamshire and Hertfordshire to its confluence with the River Colne, Hertfordshire, River Colne in Rickmansworth. The Che ...

* River Gade * River Granta * Hambleden Brook * Hogsmill River * Hughenden Stream *

* River Mimram * River Misbourne *

River Pang The River Pang is a small chalk stream river in the west of the English county of Berkshire, and a tributary of the River Thames. It runs for approximately from its source near the village of Compton, Berkshire, Compton to its confluence wi ...

* River Quin *

River Rib The River Rib is a tributary of the River Lea, which runs from Buckland in Hertfordshire, England. It flows into the River Lea to the east of Hertford. Course The River Rib originates near the East Hertfordshire village of Buckland, Hertfords ...

* River Stort * River Ver * River Wandle *

River Wye The River Wye (; ) is the Longest rivers of the United Kingdom, fourth-longest river in the UK, stretching some from its source on Plynlimon in mid Wales to the Severn Estuary. The lower reaches of the river forms part of Wales-England bor ...

Yorkshire Wolds

Chalk streams of the

: * Driffield Beck, which is a tributary of the

River Hull The River Hull is a navigable river in the East Riding of Yorkshire in Northern England. It rises from a series of springs to the west of Driffield, and enters the Humber Estuary at Kingston upon Hull. Following a period when the Archbishops o ...

Gypsey Race The Gypsey Race is a Winterbourne (stream), winterbourne stream that rises to the east of Wharram-le-Street and flows through the villages of Duggleby, Kirby Grindalythe, West Lutton, East Lutton, Helperthorpe, Weaverthorpe, Butterwick, Foxhole ...

, the most northerly chalk stream in Europe, runs east to the sea at

Bridlington Bridlington (previously known as Burlington) is a seaside town and civil parish in the East Riding of Yorkshire, England. It is on the Holderness part (Flamborough Head to the Humber estuary) of the Yorkshire Coast by the North Sea. The town is ...

* Settrington Beck, which is a tributary of the River Derwent

Lincolnshire

Chalk streams of

Lincolnshire Lincolnshire (), abbreviated ''Lincs'', is a Ceremonial counties of England, ceremonial county in the East Midlands and Yorkshire and the Humber regions of England. It is bordered by the East Riding of Yorkshire across the Humber estuary to th ...

: There are several chalk streams in the Lincolnshire Wolds including * Great Eau * River Waring * River Bain * River Lymn * River Lud, *Laceby Beck, *Nettleton Beck, *Waithe Beck,

Kent

Chalk streams of Kent: * River Dour * Nailbourne *

River Darent The Darent is a Kentish tributary of the River Thames and takes the waters of the River Cray as a tributary in the tidal portion of the Darent near Crayford. 'Darenth' is frequently found as the spelling of the river's name in older books and ...

* River Stour *(there are more in Kent than listed here)

Norfolk

Chalk streams of Norfolk: * Babingley * Bure *

Burn A burn is an injury to skin, or other tissues, caused by heat, electricity, chemicals, friction, or ionizing radiation (such as sunburn, caused by ultraviolet radiation). Most burns are due to heat from hot fluids (called scalding), soli ...

* Gaywood * Glaven * Heacham * Hun * Ingol * Mun * Nar * Stiffkey * Tas *

Waveney Waveney may refer to: * River Waveney, a river that forms the boundary between Suffolk and Norfolk, England * Waveney District, a local government district in Suffolk, England * Waveney (UK Parliament constituency) * Waveney class lifeboat, a class ...

* Wensum * Wissey * Yare * Weybourne Beck

Suffolk

Chalk streams of Suffolk: * River Lark * River Linnet

References

Notes

Citations

Sources

External links

Wildlife Trusts - chalk streamsWWF - England's Chalk Streams under threat
Includes an index of all chalk streams in England in linked report
FishPal - about chalk streams
Includes a small list of chalk streams and their locations {{Rivers, streams and springs, state=collapsed Water streams