Tw Ecology Report

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Why does Londons

river need theThames Tunnel?

T h e T h a m e s T u n n e l i s a

m a j o r n e w s e w e r , u r g e n t l y

n e e d e d t o p r o t e c t t h e R i v e r

T h a m e s a n d i t s w i l d l i f e f r o m i n c r e a s i n g p o l l u t i o n .

Thames Tunnel


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The River Thames is not as clean as you might think. Sewage rom ouroverstretched sewerage network is polluting the capitals river, a ectingmany o the sh, invertebrates, birds and aquatic mammals that live inand around the Thames Tideway.

This document describes the importance o the Thames Tidewayor wildli e and how it is being a ected by raw sewage discharges.

It will set out how the Thames Tunnel will help bring about changeto ensure sustainable sh populations in the Tideway or the uture.

The Thames Tideway stretches 110km, between the upstreamtidal limit at Teddington Lock in the west, to the open sea in theeast. The whole corridor o the Tideway, which includes the river,

oreshore and embankment, is recognised as a Site o MetropolitanImportance or Nature Conservation, since it supports a variety o species and habitats not ound elsewhere in the capital, and whichare vital to the protection o biodiversity in the region. The TidalThames is a superhighway or migratory sh and birds. It containsimportant populations o smelt and eel, as well as many rare species,such as the short snouted sea horse and the depressed river mussel.

It is totally unacceptable thatin this day and age, in a city likeLondon, we still have raw sewageemptying into the river a ter heavyrain all events, creating deadzones devoid o all li e, including

sh and the invertebrates onwhich they eed. The ThamesTunnel is the only realistic option

to protect the vital ecology andecosystems within the Thames,and it is our duty to ensure thisopportunity is not lost.

Janina GraySalmon & Trout Association

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Theiss River Prize

The River Thames won the InternationalTheiss River Prize in 2010, which celebratesoutstanding achievement in rivermanagement and restoration.

The award submission showed how the EnvironmentAgency and its partners have not just maintained

the improvements o the past, but how they areorging ahead to deliver initiatives that will helpthe River Thames continue to be an iconic river.

The London Tideway Improvements, which includesthe Thames Tunnel, was one o the projects

eatured in the submission or the prize, outliningour commitment to addressing the current sewageproblems in the Thames Tideway.

The hard work that has already gone in helpingto achieve this award is only the beginning, andthe sewage problem is still a major hurdle toovercome be ore the river reaches its ull potential.

2010

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Londons sewerage system wasbuilt during the Victorian era todeal with the capitals sewage

problems. At that time, Londonssewage was mostly depositedinto open street sewers, or oneo the many Thames tributaries,with most o the waste eventuallyentering into the River Thames.This oul material, originating

rom homes, actories andworkshops rom all acrossLondon, was so great that it

rendered the River Thameslargely devoid o aquatic li e. Sir Joseph Bazalgette designedmagni cent interceptor sewers,

ollowing the Great Stink o1858 to capture the oul materialthat was previously going into theRiver Thames. It is these sewersthat still orm the backbone o

Londons sewerage system today. Although Bazalgettes designstopped most o Londonssewage entering the capitalsriver, the River Thames remainedin a degraded state due to somuch pollution rom heavyindustry in the capital and romsewage treatment works. So

much so, that in the 1950sthe capitals river was declaredbiologically dead by scientistsat the Natural History Museum.

The introduction o the CleanRivers Act in 1960, the constructiono new sewage works by Thames

Water and its predecessorsduring the 1960s and 1970s,and the privatisation o the waterindustry, have all resulted in urthermajor investment at our sewagetreatment works. Over the last 30years, we have seen the dramaticclean up o the River Thames,making it today an example oa recovering ecosystem which is

o great ecological importance.

However, we are still relyingon a sewerage system built inVictorian times. This system wasbuilt to meet the requirementso a smaller population. With thegrowth in Londons populationthe system, which was designedto overfow into the River Thames

when ull, is starting to reach itscapacity. This means overfows arebecoming more requent. Suchsewage discharges degrade thewater quality o the River Thamesand inhibit the ecological potentialo the estuary; a problem that isonly likely to get worseas Londons population grows.

The proposed Thames Tunnelwill help to ensure that theexcellent progress in cleaningup the river is not reversed.

The River Thames a recoveringecosystem

Since the 1950s great strides havebeen taken to improve the qualityo the tidal Thames, which was

virtually li eless as a result o grosspollution. However, the success inenvironmental improvements, withthe welcome return o sh andother wildli e, is under continuousthreat rom the discharges romthe combined sewer overfows.The Thames Tunnel will end thescandal o millions o tonnes osewage overfowing into the river

annually, which seriously damagesthe ecology o the Thamesand increases the health riskto the public.

Peter FinchChairman, River Thames Society

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The need or theThames Tunnel...

Acton

Mogden

Like many older cities aroundthe world, the vast majority oLondon is served by a combinedsewerage system, which collectsboth sewage and rainwater.

The existing Victorian seweragenetwork includes 57 combinedsewer overfows (CSOs). Theseare located at intervals alongthe River Thames and dischargeuntreated water, consisting oraw sewage mixed with rainwater,directly into the River Thameswhen the combined system hasreached capacity. This preventsthe backup o sewage foodingstreets and peoples homes.

The Thames Tunnel is the nal parto the solution to tackle sewagedischarges into the River Thamesin London. It will address the CSOsidenti ed by the EnvironmentAgency as being unsatis actory,due to the pollution they cause.It will capture these CSO dischargeswhich would otherwise overfowinto the River Thames, be oretrans erring them to BecktonSewage Treatment Works.

Londons sewerage system is nowvirtually at the limit o its capacity.On average, CSO dischargeshappen more than once a weekcurrently and can be caused byas little as 2mm o rain all.

The proposed Thames Tunnel,which is the result o morethan ten years o researchand development, is the onlyviable solution to dealing withLondons dirty secret.

The current constructioncost estimate o the ThamesTunnel is 4.1 billion. De rascost bene t analysis suggeststhat as much as 5.1 billion 1 o environmental costsalone could be avoided,i the project goes ahead.

The current situation isunacceptable. Without any action,the requency and volume ooverfows will continue, pollutingthe capitals river and causing

urther environmental damage,which a ects the ecology o theRiver Thames and can have ane ect on the wildli e that livesin and around the Thames Tideway.

1 De ra, Cost and Bene ts o the Thames Tunnel Nov 2011http://www.de ra.gov.uk/publications/ les/pb13677a-thamestunnel-costsbene ts.pd

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Greenwich

Beckton

Crossness

River Lee

Riverside

Long ReachLee Tunnel

Proposed Thames Tunnel

Combined sewer overow (CSO)

Sewage treatment works

Abbey Mills

The Thames Tunnel route is indicative only.

Lee Tunnel

Proposed Thames Tunnel

Combined sewer overow (CSO)

Sewage treatment works

Thames Tideway Strategic StudyThe proposed Thames Tunnel isthe nal and most complex part othe solution to help tackle sewagedischarges and improve river waterquality in the River Thames.

In 2000, the Thames TidewayStrategic Study (TTSS) wasestablished to consider theenvironmental impact ostorm discharges to the tidalRiver Thames and to proposepotential solutions. ThamesWater, the Environment Agency,the Greater London Authority,De ra and O wat (as an observer)all contributed to the study.

The study concluded thatadditional capacity in Londonssewerage system was required, andupgrades to sewage treatmentworks in London were neededto improve the water quality inthe river and protect sh li e.

In line with the recommendationso the TTSS, three separateschemes were developed toaddress these problems: A 675million investment to

improve Londons ve principalsewage treatment works Mogden, Crossness, Beckton,Long Reach and Riverside to be completed by 2014.

The Lee Tunnel (already underconstruction) to deal with thelargest CSO point at AbbeyMills Pumping Station, whichdischarges into the River Lee.

The Thames Tunnel, to deal withthe most polluting CSOs alongthe River Thames betweenwest London and BecktonSewage Treatment Works.

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The Thames estuary is a naturesuperhighway, abundant withwildli e.

The Thames Tideway is home to avariety o aquatic and non-aquaticspecies, including mammals, birds

and sh. It provides the idealhabitat or such species to thrive.Reducing CSO discharges, throughthe proposed Thames Tunnelwill improve the water quality othe River Thames. This will helpto support such species that livein the surrounding habitats, andensure that the ecosystems thatexist within the Tideway, are

protected or the long term.

FishThe Thames Tideway is anestuary, meaning it containswater o varying salinity, allowinga variety o marine, estuarine and

reshwater sh species to thrive.Salmon, sea trout, smelt and eelsmigrate through and within the

Tideway every year.

The Thames Tideway is important,because it can support a rangeo marine and resh water shthrough di erent stages o theirli e cycle, while estuaries areimportant or species that relyupon their sheltered waters or

protection, making them idealor spawning adults and asnursery areas or young sh.

As many as 125 di erentspecies o sh have beendocumented in the RiverThames.

Species such as barbel, bream,

carp, roach and perch can largelybe ound in the upper and middletidal reaches o the River Thames,while other species such as dab,tub gurnard and dover sole canbe ound downstream in the moresaline sections o the estuary.

Many other sh species, such asbass, founder, thick lipped mullet,

sea trout and smelt also move upand down the Tideway to di erenthabitats depending on theirli ecycle stage. The short-snoutedseahorse has also recently beendiscovered in the river.

The River Thames is a keynursery area or millions o bassand founder, which are both

very important commercialand recreational angling sh.

A number o species, such assalmon, allis shad, twaite shad,river lamprey and sea lampreyare protected under nationaland international legislation,while others, such as dover soleand smelt, are the subject o

Species Action Plans under theUK Biodiversity Action Plan. Thismeans that there are speci ctargets set by the Government toconserve these species. Some othese protected species currentlyoccur only rarely in the ThamesTideway, and any improvementsin river water quality would helpthem to expand their ranges.

A wildli esuperhighway

Flounder

Dab

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The River Thames asa commercial sheryThe Thames estuary is not justo ecological importance. It alsosupports a commercial shery.Species, such as dover sole,thornback ray and bass, as well as

shell sh, such as the edible cockleand whelk, are caught and sold.

There are also many well-knownlocal London delicacies whichare associated with the RiverThames. In the 19th centuryLondoners dined on jellied eelsand whitebait suppers, and athriving industry evolved with

local pubs and eateries servingthese dishes. Today, the ThamesTideway also represents oneo the most important nurseryareas or smelt in the UK.

BirdsThe Thames estuary is one o themost important sites or water owlin the UK, supporting over 155,000wintering waders and wild owl.

Some o the habitats which border

the Thames Tideway, such asthe coastal grazing marsh andmud fats o the outer estuary,are protected under nationaland international legislationbecause they support importantpopulations o mostly winteringbirds. These populations, whichinclude species such as avocet,ringed plover, gadwall and

shoveler, eed on invertebratesin the intertidal mudfats.

Other water birds that can beound along the Tideway, within

London, include the cormorant,black-headed gull, and herringgull. The mute swan is a amiliarsight on the river, as well as manynon-native geese including

Canada geese, Egyptian geese,and bar-headed geese, and alsoducks such as the native mallard,once amiliar but now listedas an amber species Bird oConservation Concern 2.

InvertebratesThe Thames Tideway is alsohome to many invertebrates, bothwithin the river and on its banks.These include molluscs, such asthe nationally rare depressed rivermussel, which occurs close to the

tidal limit at Teddington, as well asspecies that live near the watersedge, such as the two-lipped doorsnail and the German hairy snail.

Crustaceans such as the commonshrimp are also ound in theTideway. Worms, including thecommon ragworm and thetentacled lagoon worm, which is

a nationally scarce marine animaland protected by the Wildli e andCountryside Act 1981 can alsobe ound. Exotic invaders, suchas the Chinese Mitten crab whicharrived in ships ballast water,have colonised the Tideway.

Aquatic mammalsAdditionally, many aquatic

mammals, such as the harbourporpoise, bottlenose dolphin, andvarious seal species, have all beenseen within the Thames Tidewayin recent years.

2 www.rspb.org.uk/wildli e/birdguide/status_explained.aspx

Invertebrate

Gulls, geese and moorhen

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The Thames Tideway is a vitallink and migration route ormany aquatic species.

Many species o sh migrate ona regular basis. Some travel overshort distances rom reshwatersupstream to the more salinewaters in the estuary, such as

dace, while others such as eeland salmon have li ecycles whichspan thousands o miles, makingthe Tideway part o a muchlarger migratory corridor. Fishusually migrate because o dietor reproductive needs; it is vitalthat the ecological condition othe Tideway is maintained andimproved to support these species

in their li ecycle.

Fish migration

By building the Thames Tunnel,we will also help to improve the

environment o all o the Thamestributaries reaching ar intocounties such as Hert ordshire,Surrey, Ox ordshire, Berkshire andWiltshire, as more sh and wildli ewill be able to migrate up anddown the cleaner river.

Robert OatesExecutive Director

Thames Rivers Restoration Trust

Fish studies or the Thames Tunnel

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DaceDace is a reshwater sh specieswhich spawns in both the

reshwater River Thames and theupper Thames Tideway. The namedace appears to have originated

rom dart, and this silvery whitesh may be seen darting like an

arrow rom any person or object

that may alarm it. In the Tideway,young dace disperse downstream

rom their spawning sites, butmust remain in low salinity water.To do this they seek out shallowwater at the river margins wherethe current is weaker and thereare ewer predatory adult sh.

Like all juvenile sh, young dace

are vulnerable to the e ects opoor water quality caused by CSOdischarges. Studies carried out

or the Thames Tunnel projectduring 2011, showed that the largenumbers o young dace spawnedduring the spring time were killeddue to a major CSO dischargeevent in early June 2011.

SmeltSmelt, like salmon, migrate

rom marine to estuarine andreshwater habitats to spawn.

Once an important commercialshery in the River Thames, smelt,

is now a priority species in theLondon Biodiversity Action Plan.They are known to spawn

near the mouth o the RiverWandle and elsewhere in theupper reaches o the estuary.Their name is thought to originate

rom their highly distinctive odour,comparable with cucumber.

Like dace, smelt and salmon arehighly sensitive to poor waterquality. Many juvenile smelt were

also largely eliminated a ter themajor CSO discharge event inearly June 2011.

BassBass are highly dependent onestuaries during their early li estages, generally being spawnedat sea and entering the estuary aslarvae in the springtime. They will

then move up the estuary towardsthe reshwater and saltwaterinter ace to eed over the summer,be ore migration back to the outerestuary in the autumn.

EelThe eel is a amous internationalmarine traveller, completing onlypart o its li e cycle in reshwatersor coastal areas. Spawning takesplace in the spring all the wayover in the Sargasso Sea, betweenBermuda and the Bahamas.

The eel larvae then migrate romthe Sargasso Sea to the Europeancoast, changing into what iscalled the glass eel stage be orecontinuing with their migrationinto the Thames Estuary andmaturing to the elver. To helptheir passage through the estuaryand into the River Thames theyuse the tidal currents, migrating

upstream on the food tide.

In resh water the eel lives on ornear the bottom, o ten digginginto the gravel, and migrate slowlyupstream. Male eels can stayin the reshwaters o the RiverThames or between seven and12 years, while emales staybetween nine to 20 years and

mature. When the sh maturethey change to a blue/silverycolour and migrate back seawardduring the autumn.

The River Thames is an important habitat and an essentialpart o the li e cycle o all species o sh, including bothmarine and reshwater sh. A clean, unpolluted River Thames

is essential to ensure sh species can fourish and theirmigratory habits be sustained.

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Londons sewage a cocktail o pollutantsCSO discharges contain a mixtureo oul sewage, originating rom

homes and industry, and sur aceruno rom roads, roo s andhouse drains.

Any product that is fusheddown the toilet, or which ndsits way into a drain, is likely tobe ound in the discharge roma CSO. This includes all aspectsassociated with human waste,

including pathogenic bacteriaand viruses, as well aspharmaceutical products,petroleum residues, paints,pesticides, plastics, ertilisers,

ats, oils and heavy metals.

Pollutants including solids andorganic material are ound

in sewage, which contributessigni cantly to the organic andchemical oxygen demand inthe river. This in turn can resultin nutrient enrichment and sooxygen depletion o the RiverThames in London. Theseconditions are most prevalentduring summer months, whentemperatures are higher and

oxygen in the river is subjectto greater depletion.

Mixed with rainwater, the sewagecontent o the dischargesranges rom ten to 90 percent, depending on conditions.Such regular sewage overfowsrepresent a health hazard tohuman users o the river and

causes real damage to theecology o the River Thames.

Mixed with rainwater,the sewage content of thedischarges ranges from

10 %-90 %depending on conditions

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The River Thames basin does not generate large natural

river fows, which are urther reduced by abstractionsrom the Thames upstream o Teddington, within agreed

environmental limits, or use as a water supply or London.

This means that the tidal River Thames does not receivelarge fows o reshwater rom upstream to provide dilutionand protection rom pollution. As a consequence, there isa very slow net seaward movement o fow, causing waterto take up to three months in the summer to travel alongthe estuary rom Teddington to Southend.

CSO discharges along the Thames Tideway can result ina body o polluted river water that moves up and down theriver due to tidal movements and, depending on the volumeo water fowing over Teddington Weir, the net downstreammovement o water within the Tideway may at times be aslittle as 1.5km per day towards the sea.

Sewage pollution can there ore remain within theRiver Thames or between three weeks to three months

exacerbating the e ects o the discharges on theThames Tideway.

The River Thames should be throbbing with birds and aquatic li e. Sadly, everytime we get heavy rain, the capitals drains ll and overspill, resulting in raw sewageentering the river. This rips oxygen rom the water and pollutes the whole system.The Victorians managed to clean-up the River Thames, so we can too. Imaginea Thames brim- ull o sh, eels, waders and water owl. Wildli e rom around the

world, living gill by wing alongside us Londoners. I know which Id pre er to see asI walk along the Southbank or explore the whar s o the mighty Thames.

Tim Webb Royal Society or the Protection o Birds

Sewage resting on the sur aceo the Tidal Thames

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Sewage overfows havean adverse e ect on theenvironmental quality o theRiver Thames, and can causeadverse environmental impactson sh species, especially asthe overfows are untreated,

causing high levels o pollutantsto be discharged into the river.

Fish kills Fish are considered to be goodindicators o ecological quality.The principal cause o shmortality in the Thames Tidewayarises rom low dissolved oxygenlevels, especially associated

with the operation o CSOs.

When sewage is discharged intowater, micro-organisms (bacteriaand protozoans) begin to breakdown the organic matter withinit. While doing so, they use upoxygen within the water to thedetriment o water quality and,under extreme conditions, the

loss o oxygen can kill sh andother aquatic organisms. Theproblem is particularly acuteduring the summer when thewater is warmer, and oxygenis more readily lost rom it.

Warm weather in April and May2011, ollowed by heavy rain inearly June 2011, resulted in a large

amount o raw sewage beingdischarged rom CSOs throughoutthe Thames Tideway and romMogden Sewage TreatmentWorks. The monitoring o young

sh populations by the ThamesTunnel Project recorded the totalloss o young smelt in the ThamesTideway a ter the middle o June.

Repeated events like this duringthe early summer period whenyoung sh are vulnerable to lowlevels o dissolved oxygen couldhave signi cant implications orthe conservation o this importantspecies. Interception o the CSOs

throughout the Tideway wouldresult in signi cantly ewer lowoxygen events.

The e ects o sewage on wildli e

The very location o London wasdetermined by the great meeting

point o marine and reshwaterecology that provided plenti ulood to Londoners or thousands

o years. The estuary is poisedto recover this role, but it cannotdo so unless the problem ooverfowing sewers is tackled.A restored river would providea massive boost to the anglingindustry in London and help the

sea angling and commercialsheries o the outer estuary andthe North Sea. The only easibleway to achieve this vision, and themost cost-e ective, is to build theThames Tunnel. It should havebeen built decades ago.

Mark LloydChie Executive

Angling Trust

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26,000

On 6 June 2011, a ter 30mm o rain all, more than 450,000 cubicmetres o storm sewage romsewage treatment works andCSOs discharged into the river.This is equivalent in volume toover 85,000 ull builders skips.

It is estimated that as many as

sh died in June 2011.

This number included a signi cantnumber o juvenile sh and

species o conservation interestsuch as sea trout, eel and smelt.

Tideway Fish Risk Model (TFRM), August 2004Dissolved oxygen is monitored by the EnvironmentAgency to assess river water quality.

The TFRM was developed as a means oquanti ying the risks o low dissolved oxygen levelson sh stocks in the Thames Tideway. Dissolved

oxygen levels recorded by the Environment Agencyat a series o locations throughout the Tidewaywere compared with known dissolved oxygenrequirements or a variety o sh species.

The study ound that low dissolved oxygenconditions in the upper Tideway may havecaused more than 90% mortality o sh suchas dace and smelt ollowing a speci c lowdissolved oxygen event in summer 2004.

The same event prevented salmon rom enteringthe reshwater reaches above Teddington.

The ndings rom the TFRM were used as abasis or establishing dissolved oxygen standards

or the Thames Estuary. The TFRM demonstratesthat Tideway sh populations would becomesustainable and would be expected to survivein the long term once the Thames Tunnel is

operational.

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AmmoniaAmmonia, which is a constituento sewage, is poisonous to sh,invertebrates and other aquaticli e. It causes stress and damagesgills and other tissues, even in verysmall amounts. It is also oxidisedby bacteria in water causing adepletion o dissolved oxygen.

Fish exposed to low levels oammonia, over time, are moresusceptible to bacterial in ectionsand have poor growth, while inhigher concentrations it can resultin sh kills.

Ammonia is present in the watercolumn, but it also accumulates

in the river bed in the vicinity oa CSO discharge.

The sewage discharged can also,contain un-ionised ammonia.This is a orm o ammonia thatarises under conditions o hightemperature and/or alkalineconditions and is even more toxicto reshwater organisms than

other orms o ammonia.

By reducing or removingdischarges rom the CSOs thesehigh levels o ammonia willbegin to reduce through naturalprocesses, allowing invertebratesto return to the sediments in thevicinity o the out all. This willhave real bene ts or the shand water owl that eed on them.

Bream

It is unacceptable on any level totolerate raw sewage in the RiverThames, not only or Londonscommunities who have to put up

with the repellent and dangerousmatter that is within sight, smelland touch o neighbourhoodareas, but also because o thedetrimental e ects it has on thewater quality and ecology o ourcapitals river. Sewage rom CSOdischarges can harm all the wildli ethat live in and around theThames Tideway, rom the many

di erent sh species that can nowbe ound in the River Thames, tothe birds and aquatic mammalsthat also live along the river.Dealing with it right now is nota luxury, it is a necessity to ensurethe uture health and ecologyo the River Thames.

Debbie Leach

Chie ExecutiveThames 21

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LitterThe sewage content o CSOdischarges also includes litter.All sorts o sanitary and personalhealthcare products enter theRiver Thames, through the CSOs.Items fushed down the toilet,such as sanitary towels, cottonbuds, condoms and syringes are

regularly ound foating downthe River Thames, or washedup on the oreshore. Not onlyare these products unsightly,but once in the environment theplastic parts never really go away they just break down into smallerand smaller pieces.

Once non-degradable material

becomes small enough, theseparticles can be ingested bydeposit eeding worms and otheraquatic invertebrates which eedby consuming sediment. Thiscan result in the accumulation oplastic particles since they cannotbe digested. This represents aroute by which plastics can beincorporated into the ood chain

and up to higher levels in the oodweb, such as sh and birds.

Many birds and aquatic mammals,such as dolphins and porpoisesalso ingest foating plasticproducts, which are dri ting withinthe water column, mistaking them

or ood. This can create blockageswithin the digestive tract and

ultimately result in the deatho the animal.

Such solid material within thesewage, including aeces andlitter, settle on the sur ace o thesediment around the CSO leadingto a change in the nature o theriver bed, particularly where thenatural bed is characterized bygravel. By removing the CSOdischarge and allowing this

material to be washed away,the river bed will return to a morenatural condition, providing newareas o habitat or sh andinvertebrates.

Currently it is estimated that over10,000 tonnes o sewage relatedlitter enters the River Thames

rom CSOs, every year. While the

commissioning o the Lee Tunneland improvements at Becktonand Crossness sewage treatmentworks will remove more thanhal the volume o CSO e fuentcurrently discharged to the RiverThames, the Lee Tunnel will onlyaddress a small proportion othe total number o spill events.They will not deliver any reduction

in the amount o sewage litter inthe upper reaches where the issueis greatest.

Once the proposed ThamesTunnel is in operation, theamount o litter is predicted

to be reduced by over 90%.

This will bring both ecologicaland aesthetic bene ts to theThames Tideway and widerregion.

over 90 %reduction in litter

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Legislation

The Thames Tunnel will help ensure that the UK continuesto comply with a number o EU Directives. These include theUrban Waste Water Treatment Directive (UWWTD) and the

Water Framework Directive (WFD), both o which are designedto clean up rivers to improve their water quality and ecology.

The UWWTD requires that wastewater is properly collectedand treated be ore discharge, other than a ter exceptionalconditions, such as unusually heavy rain all. The WFD also aimsto maintain and improve the aquatic environment through theimplementation o river basin management plans.

The construction o the Thames Tunnel is one o a number o

actions which are set out in the Thames River Basin ManagementPlan, which will help the Thames Tideway to achieve its waterquality and ecological objectives. The UK has given a commitmentto the European Commission to the construction o a ThamesTunnel, with an estimated completion date o 2022/23, as parto the continued implementation o the UWWTD.

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The Thames Tunnel is essentiali we want to help protect andsustain the ecosystems withinthe Thames Tideway and improvethe ecology o the capitals river.

Without the constructiono the Thames Tunnel weare likely to see more requentCSO discharges, resulting in

urther environmental andecological damage, as wellas increased litter.

Less sewage entering the RiverThames and being capturedby the Thames Tunnel willhelp ensure: The UK will continue to meet

its commitments under theUWWTD and the WFD.

Existing sh populations will

be sustainable in the long term,leading to bene ts or wildli eand the many anglers thatuse the Thames Tideway.

The potential for increasedbiodiversity and a greaterabundance o sh will berealised, including sensitivespecies and species oconservation interest suchas shad, smelt, eels, and riverand sea lamprey.

The communities of sh andinvertebrates in the ThamesTideway will be more balanced,with a greater number ospecies, particularly in thevicinity o the CSOs. This couldhave bene ts or the birdpopulations that eed o them.

Biologically dead or many years,there is now a much greaterdiversity o wildli e in the river

that needs to be protectedrom the increasingly requentoverfows o sewage into theriver. The proposed ThamesTunnel will help to ensure thatthe cleaning up o the RiverThames and improvementsto water quality continues.

The ecologicalbenefts o theThames Tunnel

Construction o theThames Tunnel

A comprehensive EnvironmentImpact Assessment, currentlybeing undertaken or the ThamesTunnel project, will ensure thatall o the possible impacts on theThames Tideway and its wildli ehave been identi ed.

Measures have been incorporatedinto the design o the scheme

to ensure the least disruption toecosystems within the ThamesTideway including: control measures to prevent

spills o chemicals or silty waterinto the river during construction

restrictions on dredging and piling to protect shspawning areas

use of specialist piling techniquesto minimise under water noiseand vibration

careful consideration of lightingto minimise disturbance toaquatic wildli e

provision of timber fenders onpermanent oreshore structuresto promote aquatic habitats.

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A great number o the WWTsLondons Wetland Centreswater owl utilise the tidal

Thames. As well as a super-highway or migratory birds inthe city centre, the River Thamesis regularly used at low tide bywild owl such as Common Tealand Mallard. Fish eating birdsalso occur on the tidal Thamessuch as the Grey Heron,Cormorant and Great CrestedGrebe. The water the London

Wetland Centre receives is oa reasonable quality; but doescontain quite high levels ophosphate. The Thames Tunnelwould prevent major CSOdischarges into the tidal Thamesimproving the quality o thewater, or both sh species andthe many water and wild owlthat live in and around the

Thames Tideway.

Carrie HumeHead o Conservation PolicyWild owl & Wetlands Trust(WWT)

A heron caught up in CSO discharge near Hammersmith Bridge in 2011

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For urther in ormation see our website:www.thamestunnelconsultation.co.uk

The Thames Tunnel is essential to help protect andsustain the ecosystems within the Thames Tideway andimprove the ecology o the capitals river or the uture.

Documents

Tw Ecology Report