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Why does London’s river need the Thames Tunnel? The major Thames need new se Tunnel Tham ed to pr wer, urge is a ntly es an otect incre d its wi the Rive asing ldlife r from pollu tion.

Thames Tunnel

The River Thames is not as clean as you might think. Sewage from our overstretched sewerage network is polluting the capital’s river, affecting many of the fish, invertebrates, birds and aquatic mammals that live in and around the Thames Tideway. This document describes the importance of the Thames Tideway for wildlife and how it is being affected by raw sewage discharges. It will set out how the Thames Tunnel will help bring about change to ensure sustainable fish populations in the Tideway for the future. The Thames Tideway stretches 110km, between the upstream tidal limit at Teddington Lock in the west, to the open sea in the east. The whole corridor of the Tideway, which includes the river, foreshore and embankment, is recognised as a Site of Metropolitan Importance for Nature Conservation, since it supports a variety of species and habitats not found elsewhere in the capital, and which are vital to the protection of biodiversity in the region. The Tidal Thames is a superhighway for migratory fish and birds. It contains important populations of 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 that in this day and age, in a city like London, we still have raw sewage emptying into the river after heavy rainfall events, creating dead zones devoid of all life, including fish and the invertebrates on which they feed. The Thames Tunnel is the only realistic option to protect the vital ecology and ecosystems within the Thames, and it is our duty to ensure this opportunity is not lost. Janina Gray Salmon & Trout Association

Theiss River Prize


The River Thames won the International Theiss River Prize in 2010, which celebrates outstanding achievement in river management and restoration. The award submission showed how the Environment Agency and its partners have not just maintained the improvements of the past, but how they are forging ahead to deliver initiatives that will help the River Thames continue to be an iconic river. The London Tideway Improvements, which includes the Thames Tunnel, was one of the projects featured in the submission for the prize, outlining our commitment to addressing the current sewage problems in the Thames Tideway. The hard work that has already gone in helping to achieve this award is only the beginning, and the sewage problem is still a major hurdle to overcome before the river reaches its full potential.


The River Thames – a recovering ecosystem London’s sewerage system was built during the Victorian era to deal with the capital’s sewage problems. At that time, London’s sewage was mostly deposited into open street sewers, or one of the many Thames tributaries, with most of the waste eventually entering into the River Thames. This foul material, originating from homes, factories and workshops from all across London, was so great that it rendered the River Thames largely devoid of aquatic life. Sir Joseph Bazalgette designed magnificent interceptor sewers, following the ‘Great Stink’ of 1858 to capture the foul material that was previously going into the River Thames. It is these sewers that still form the backbone of London’s sewerage system today. Although Bazalgette’s design stopped most of London’s sewage entering the capital’s river, the River Thames remained in a degraded state due to so much pollution from heavy industry in the capital and from sewage treatment works. So much so, that in the 1950’s the capital’s river was declared ‘biologically dead’ by scientists at the Natural History Museum.

The introduction of the Clean Rivers Act in 1960, the construction of new sewage works by Thames Water and its predecessors during the 1960s and 1970s, and the privatisation of the water industry, have all resulted in further major investment at our sewage treatment works. Over the last 30 years, we have seen the dramatic clean up of the River Thames, making it today an example of a recovering ecosystem which is of great ecological importance. However, we are still relying on a sewerage system built in Victorian times. This system was built to meet the requirements of a smaller population. With the growth in London’s population the system, which was designed to overflow into the River Thames when full, is starting to reach its capacity. This means overflows are becoming more frequent. Such sewage discharges degrade the water quality of the River Thames and inhibit the ecological potential of the estuary; a problem that is only likely to get worse as London’s population grows.

Since the 1950s great strides have been taken to improve the quality of the tidal Thames, which was virtually lifeless as a result of gross pollution. However, the success in environmental improvements, with the welcome return of fish and other wildlife, is under continuous threat from the discharges from the combined sewer overflows. The Thames Tunnel will end the scandal of millions of tonnes of sewage overflowing into the river annually, which seriously damages the ecology of the Thames and increases the health risk to the public. Peter Finch Chairman, River Thames Society

The proposed Thames Tunnel will help to ensure that the excellent progress in cleaning up the river is not reversed. 3

The need for the Thames Tunnel... Like many older cities around the world, the vast majority of London is served by a combined sewerage system, which collects both sewage and rainwater. The existing Victorian sewerage network includes 57 combined sewer overflows (CSOs). These are located at intervals along the River Thames and discharge untreated water, consisting of raw sewage mixed with rainwater, directly into the River Thames when the combined system has reached capacity. This prevents the backup of sewage flooding streets and people’s homes.

The Thames Tunnel is the final part of the solution to tackle sewage discharges into the River Thames in London. It will address the CSOs identified by the Environment Agency as being unsatisfactory, due to the pollution they cause. It will capture these CSO discharges which would otherwise overflow into the River Thames, before transferring them to Beckton Sewage Treatment Works. London’s sewerage system is now virtually at the limit of its capacity. On average, CSO discharges happen more than once a week currently and can be caused by as little as 2mm of rainfall.

The current construction cost estimate of the Thames Tunnel is £4.1 billion. Defra’s cost benefit analysis suggests that as much as £5.1 billion1 of environmental costs alone could be avoided, if the project goes ahead. The current situation is unacceptable. Without any action, the frequency and volume of overflows will continue, polluting the capital’s river and causing further environmental damage, which affects the ecology of the River Thames and can have an effect on the wildlife that lives in and around the Thames Tideway.

The proposed Thames Tunnel, which is the result of more than ten years of research and development, is the only viable solution to dealing with ‘London’s dirty secret.’


Mogden 1


 efra, Cost and Benefits of the Thames Tunnel Nov 2011 D http://www.defra.gov.uk/publications/files/pb13677a-thamestunnel-costsbenefits.pdf

Thames Tideway Strategic Study The proposed Thames Tunnel is the final and most complex part of the solution to help tackle sewage discharges and improve river water quality in the River Thames. In 2000, the Thames Tideway Strategic Study (TTSS) was established to consider the environmental impact of storm discharges to the tidal River Thames and to propose potential solutions. Thames Water, the Environment Agency, the Greater London Authority, Defra and Ofwat (as an observer) all contributed to the study.

The study concluded that additional capacity in London’s sewerage system was required, and upgrades to sewage treatment works in London were needed to improve the water quality in the river and protect fish life. In line with the recommendations of the TTSS, three separate schemes were developed to address these problems: • A £675million investment to improve London’s five principal sewage treatment works – Mogden, Crossness, Beckton, Long Reach and Riverside – to be completed by 2014.

• The Lee Tunnel (already under construction) to deal with the largest CSO point at Abbey Mills Pumping Station, which discharges into the River Lee. • The Thames Tunnel, to deal with the most polluting CSOs along the River Thames between west London and Beckton Sewage Treatment Works.

Abbey Mills Abbey Mills

Abbey Mills River Lee

River Lee




River Lee


Riverside Crossness Crossness Crossness




Lee Tunnel

Lee Tunnel

Proposed Thames Tunnel

Proposedsewer Thames Tunnel Combined overflow (CSO) Lee Tunnel

Combined sewerworks overflow (CSO) Sewage treatment

Proposed Thames Tunnel

Sewage treatment works

Combined sewer overflow (CSO) Sewage treatment works

Long Reach

The Thames Tunnel route is indicative only.

The Thames Tunnel route is indicative only.


A wildlife superhighway The Thames estuary is a nature superhighway, abundant with wildlife. The Thames Tideway is home to a variety of aquatic and non-aquatic species, including mammals, birds and fish. It provides the ideal habitat for such species to thrive. Reducing CSO discharges, through the proposed Thames Tunnel will improve the water quality of the River Thames. This will help to support such species that live in the surrounding habitats, and ensure that the ecosystems that exist within the Tideway, are protected for the long term. Fish The Thames Tideway is an estuary, meaning it contains water of varying salinity, allowing a variety of marine, estuarine and freshwater fish species to thrive. Salmon, sea trout, smelt and eels migrate through and within the Tideway every year.

The Thames Tideway is important, because it can support a range of marine and fresh water fish through different stages of their life cycle, while estuaries are important for species that rely upon their sheltered waters for protection, making them ideal for spawning adults and as nursery areas for young fish. As many as 125 different species of fish have been documented in the River Thames. Species such as barbel, bream, carp, roach and perch can largely be found in the upper and middle tidal reaches of the River Thames, while other species such as dab, tub gurnard and dover sole can be found downstream in the more saline sections of the estuary. Many other fish species, such as bass, flounder, thick lipped mullet, sea trout and smelt also move up and down the Tideway to different habitats depending on their lifecycle stage. The short-snouted seahorse has also recently been discovered in the river. The River Thames is a key nursery area for millions of bass and flounder, which are both very important commercial and recreational angling fish.


A number of species, such as salmon, allis shad, twaite shad, river lamprey and sea lamprey are protected under national and international legislation, while others, such as dover sole and smelt, are the subject of Species Action Plans under the UK Biodiversity Action Plan. This means that there are specific targets set by the Government to conserve these species. Some of these protected species currently occur only rarely in the Thames Tideway, and any improvements in river water quality would help them to expand their ranges.



Birds The Thames estuary is one of the most important sites for waterfowl in the UK, supporting over 155,000 wintering waders and wildfowl.

Gulls, geese and moorhen

The River Thames as a commercial fishery The Thames estuary is not just of ecological importance. It also supports a commercial fishery. Species, such as dover sole, thornback ray and bass, as well as shellfish, such as the edible cockle and whelk, are caught and sold. There are also many well-known local London delicacies which are associated with the River Thames. In the 19th century Londoners dined on ‘jellied eels’ and ‘whitebait suppers,’ and a thriving industry evolved with local pubs and eateries serving these dishes. Today, the Thames Tideway also represents one of the most important nursery areas for smelt in the UK.

Some of the habitats which border the Thames Tideway, such as the coastal grazing marsh and mud flats of the outer estuary, are protected under national and international legislation because they support important populations of mostly wintering birds. These populations, which include species such as avocet, ringed plover, gadwall and shoveler, feed on invertebrates in the intertidal mudflats. Other water birds that can be found along the Tideway, within London, include the cormorant, black-headed gull, and herring gull. The mute swan is a familiar sight on the river, as well as many non-native geese including Canada geese, Egyptian geese, and bar-headed geese, and also ducks such as the native mallard, once familiar but now listed as an ‘amber’ species Bird of Conservation Concern2.

Invertebrates The Thames Tideway is also home to many invertebrates, both within the river and on its banks. These include molluscs, such as the nationally rare depressed river mussel, which occurs close to the tidal limit at Teddington, as well as species that live near the water’s edge, such as the two-lipped door snail and the German hairy snail. Crustaceans such as the common shrimp are also found in the Tideway. Worms, including the common ragworm and the tentacled lagoon worm, which is a nationally scarce marine animal and protected by the Wildlife and Countryside Act 1981 can also be found. Exotic invaders, such as the Chinese Mitten crab which arrived in ships ballast water, have colonised the Tideway.



w  ww.rspb.org.uk/wildlife/birdguide/status_explained.aspx

Aquatic mammals Additionally, many aquatic mammals, such as the harbour porpoise, bottlenose dolphin, and various seal species, have all been seen within the Thames Tideway in recent years. 7

Fish migration The Thames Tideway is a vital link and migration route for many aquatic species. Many species of fish migrate on a regular basis. Some travel over short distances from freshwaters upstream to the more saline waters in the estuary, such as dace, while others such as eel and salmon have lifecycles which span thousands of miles, making the Tideway part of a much larger migratory corridor. Fish usually migrate because of diet or reproductive needs; it is vital that the ecological condition of the Tideway is maintained and improved to support these species in their lifecycle.

Fish studies for the Thames Tunnel

By building the Thames Tunnel, we will also help to improve the environment of all of the Thames tributaries reaching far into counties such as Hertfordshire, Surrey, Oxfordshire, Berkshire and Wiltshire, as more fish and wildlife will be able to migrate up and down the cleaner river. Robert Oates Executive Director Thames Rivers Restoration Trust


Dace Dace is a freshwater fish species which spawns in both the freshwater River Thames and the upper Thames Tideway. The name ‘dace’ appears to have originated from ‘dart’, and this silvery white fish may be seen ‘darting like an arrow from any person or object that may alarm it’. In the Tideway, young dace disperse downstream from their spawning sites, but must remain in low salinity water. To do this they seek out shallow water at the river margins where the current is weaker and there are fewer predatory adult fish. Like all juvenile fish, young dace are vulnerable to the effects of poor water quality caused by CSO discharges. Studies carried out for the Thames Tunnel project during 2011, showed that the large numbers of young dace spawned during the spring time were killed due to a major CSO discharge event in early June 2011.

Smelt Smelt, like salmon, migrate from marine to estuarine and freshwater habitats to spawn. Once an important commercial fishery in the River Thames, smelt, is now a priority species in the London Biodiversity Action Plan. They are known to spawn near the mouth of the River Wandle and elsewhere in the upper reaches of the estuary. Their name is thought to originate from their highly distinctive odour, comparable with cucumber. Like dace, smelt and salmon are highly sensitive to poor water quality. Many juvenile smelt were also largely eliminated after the major CSO discharge event in early June 2011. Bass Bass are highly dependent on estuaries during their early life stages, generally being spawned at sea and entering the estuary as larvae in the springtime. They will then move up the estuary towards the freshwater and saltwater interface to feed over the summer, before migration back to the outer estuary in the autumn.

Eel The eel is a famous international marine traveller, completing only part of its life cycle in freshwaters or coastal areas. Spawning takes place in the spring all the way over in the Sargasso Sea, between Bermuda and the Bahamas. The eel larvae then migrate from the Sargasso Sea to the European coast, changing into what is called the ‘glass eel’ stage before continuing with their migration into the Thames Estuary and maturing to the elver. To help their passage through the estuary and into the River Thames they use the tidal currents, migrating upstream on the flood tide. In fresh water the eel lives on or near the bottom, often digging into the gravel, and migrate slowly upstream. Male eels can stay in the freshwaters of the River Thames for between seven and 12 years, while females stay between nine to 20 years and mature. When the fish mature they change to a blue/silvery colour and migrate back seaward during the autumn.

The River Thames is an important habitat and an essential part of the life cycle of all species of fish, including both marine and freshwater fish. A clean, unpolluted River Thames is essential to ensure fish species can flourish and their migratory habits be sustained.


London’s sewage – a cocktail of pollutants CSO discharges contain a mixture of foul sewage, originating from homes and industry, and surface runoff from roads, roofs and house drains. Any product that is flushed down the toilet, or which finds its way into a drain, is likely to be found in the discharge from a CSO. This includes all aspects associated with human waste, including pathogenic bacteria and viruses, as well as pharmaceutical products, petroleum residues, paints, pesticides, plastics, fertilisers, fats, oils and heavy metals.

Mixed with rainwater, the sewage content of the discharges ranges from

10%-90% depending on conditions


Pollutants including solids and organic material are found in sewage, which contributes significantly to the organic and chemical oxygen demand in the river. This in turn can result in nutrient enrichment and so oxygen depletion of the River Thames in London. These conditions are most prevalent during summer months, when temperatures are higher and oxygen in the river is subject to greater depletion. Mixed with rainwater, the sewage content of the discharges ranges from ten to 90 per cent, depending on conditions. Such regular sewage overflows represent a health hazard to human users of the river and causes real damage to the ecology of the River Thames.

The River Thames should be throbbing with birds and aquatic life. Sadly, every time we get heavy rain, the capital’s drains fill and overspill, resulting in raw sewage entering the river. This rips oxygen from the water and pollutes the whole system. The Victorians managed to clean-up the River Thames, so we can too. Imagine a Thames brim-full of fish, eels, waders and waterfowl. Wildlife from around the world, living gill by wing alongside us Londoners. I know which I’d prefer to see as I walk along the Southbank or explore the wharfs of the mighty Thames. Tim Webb Royal Society for the Protection of Birds

The River Thames basin does not generate large natural river flows, which are further reduced by abstractions from the Thames upstream of Teddington, within agreed environmental limits, for use as a water supply for London. This means that the tidal River Thames does not receive large flows of freshwater from upstream to provide dilution and protection from pollution. As a consequence, there is a very slow net seaward movement of flow, causing water to take up to three months in the summer to travel along the estuary from Teddington to Southend. CSO discharges along the Thames Tideway can result in a body of polluted river water that moves up and down the river due to tidal movements and, depending on the volume of water flowing over Teddington Weir, the net downstream movement of water within the Tideway may at times be as little as 1.5km per day towards the sea. Sewage pollution can therefore remain within the River Thames for between three weeks to three months exacerbating the effects of the discharges on the Thames Tideway. Sewage resting on the surface of the Tidal Thames


The effects of sewage on wildlife Sewage overflows have an adverse effect on the environmental quality of the River Thames, and can cause adverse environmental impacts on fish species, especially as the overflows are untreated, causing high levels of pollutants to be discharged into the river.

The very location of London was determined by the great meeting point of marine and freshwater ecology that provided plentiful food to Londoners for thousands of years. The estuary is poised to recover this role, but it cannot do so unless the problem of overflowing sewers is tackled. A restored river would provide a massive boost to the angling industry in London and help the sea angling and commercial fisheries of the outer estuary and the North Sea. The only feasible way to achieve this vision, and the most cost-effective, is to build the Thames Tunnel. It should have been built decades ago. Mark Lloyd Chief Executive Angling Trust


Fish kills Fish are considered to be good indicators of ecological quality. The principal cause of fish mortality in the Thames Tideway arises from low dissolved oxygen levels, especially associated with the operation of CSOs. When sewage is discharged into water, micro-organisms (bacteria and protozoans) begin to break down the organic matter within it. While doing so, they use up oxygen within the water to the detriment of water quality and, under extreme conditions, the loss of oxygen can kill fish and other aquatic organisms. The problem is particularly acute during the summer when the water is warmer, and oxygen is more readily lost from it. Warm weather in April and May 2011, followed by heavy rain in early June 2011, resulted in a large amount of raw sewage being discharged from CSOs throughout the Thames Tideway and from Mogden Sewage Treatment Works. The monitoring of young fish populations by the Thames Tunnel Project recorded the total loss of young smelt in the Thames Tideway after the middle of June.

Repeated events like this during the early summer period when young fish are vulnerable to low levels of dissolved oxygen could have significant implications for the conservation of this important species. Interception of the CSOs throughout the Tideway would result in significantly fewer low oxygen events.

On 6 June 2011, after 30mm of rainfall, more than 450,000 cubic metres of storm sewage from sewage treatment works and CSOs discharged into the river. This is equivalent in volume to over 85,000 full builders’ skips. It is estimated that as many as

26,000 fish died in June 2011. This number included a significant number of juvenile fish and species of conservation interest such as sea trout, eel and smelt.

Tideway Fish Risk Model (TFRM), August 2004 Dissolved oxygen is monitored by the Environment Agency to assess river water quality. The TFRM was developed as a means of quantifying the risks of low dissolved oxygen levels on fish stocks in the Thames Tideway. Dissolved oxygen levels recorded by the Environment Agency at a series of locations throughout the Tideway were compared with known dissolved oxygen requirements for a variety of fish species. The study found that low dissolved oxygen conditions in the upper Tideway may have caused more than 90% mortality of fish such as dace and smelt following a specific low dissolved oxygen event in summer 2004. The same event prevented salmon from entering the freshwater reaches above Teddington. The findings from the TFRM were used as a basis for establishing dissolved oxygen standards for the Thames Estuary. The TFRM demonstrates that Tideway fish populations would become sustainable and would be expected to survive in the long term once the Thames Tunnel is operational.


Ammonia Ammonia, which is a constituent of sewage, is poisonous to fish, invertebrates and other aquatic life. It causes stress and damages gills and other tissues, even in very small amounts. It is also oxidised by bacteria in water causing a depletion of dissolved oxygen. Fish exposed to low levels of ammonia, over time, are more susceptible to bacterial infections and have poor growth, while in higher concentrations it can result in fish kills.


Ammonia is present in the water column, but it also accumulates in the river bed in the vicinity of a CSO discharge. The sewage discharged can also, contain un-ionised ammonia. This is a form of ammonia that arises under conditions of high temperature and/or alkaline conditions and is even more toxic to freshwater organisms than other forms of ammonia.

By reducing or removing discharges from the CSOs these high levels of ammonia will begin to reduce through natural processes, allowing invertebrates to return to the sediments in the vicinity of the outfall. This will have real benefits for the fish and waterfowl that feed on them.

It is unacceptable on any level to tolerate raw sewage in the River Thames, not only for London’s communities who have to put up with the repellent and dangerous matter that is within sight, smell and touch of neighbourhood areas, but also because of the detrimental effects it has on the water quality and ecology of our capital’s river. Sewage from CSO discharges can harm all the wildlife that live in and around the Thames Tideway, from the many different fish species that can now be found in the River Thames, to the birds and aquatic mammals that also live along the river. Dealing with it right now is not a luxury, it is a necessity to ensure the future health and ecology of the River Thames. Debbie Leach Chief Executive Thames 21


Litter The sewage content of CSO discharges also includes litter. All sorts of sanitary and personal healthcare products enter the River Thames, through the CSOs. Items flushed down the toilet, such as sanitary towels, cotton buds, condoms and syringes are regularly found floating down the River Thames, or washed up on the foreshore. Not only are these products unsightly, but once in the environment the plastic parts never really go away – they just break down into smaller and smaller pieces. Once non-degradable material becomes small enough, these particles can be ingested by deposit feeding worms and other aquatic invertebrates which feed by consuming sediment. This can result in the accumulation of plastic particles since they cannot be digested. This represents a route by which plastics can be incorporated into the food chain and up to higher levels in the food web, such as fish and birds. Many birds and aquatic mammals, such as dolphins and porpoises also ingest floating plastic products, which are drifting within the water column, mistaking them for food. This can create blockages within the digestive tract and ultimately result in the death of the animal.

Such solid material within the sewage, including faeces and litter, settle on the surface of the sediment around the CSO leading to a change in the nature of the river bed, particularly where the natural bed is characterized by gravel. By removing the CSO discharge and allowing this material to be washed away, the river bed will return to a more natural condition, providing new areas of habitat for fish and invertebrates. Currently it is estimated that over 10,000 tonnes of sewage related litter enters the River Thames from CSOs, every year. While the commissioning of the Lee Tunnel and improvements at Beckton and Crossness sewage treatment works will remove more than half the volume of CSO effluent currently discharged to the River Thames, the Lee Tunnel will only address a small proportion of the total number of spill events. They will not deliver any reduction in the amount of sewage litter in the upper reaches where the issue is greatest.

over 90%

reduction in litter Once the proposed Thames Tunnel is in operation, the amount of litter is predicted to be reduced by over 90%. This will bring both ecological and aesthetic benefits to the Thames Tideway and wider region.


Legislation The Thames Tunnel will help ensure that the UK continues to comply with a number of EU Directives. These include the Urban Waste Water Treatment Directive (UWWTD) and the Water Framework Directive (WFD), both of which are designed to clean up rivers to improve their water quality and ecology. The UWWTD requires that wastewater is properly collected and treated before discharge, other than after ‘exceptional’ conditions, such as unusually heavy rainfall. The WFD also aims to maintain and improve the aquatic environment through the implementation of river basin management plans. The construction of the Thames Tunnel is one of a number of actions which are set out in the Thames River Basin Management Plan, which will help the Thames Tideway to achieve its water quality and ecological objectives. The UK has given a commitment to the European Commission to the construction of a Thames Tunnel, with an estimated completion date of 2022/23, as part of the continued implementation of the UWWTD.


The ecological benefits of the Thames Tunnel The Thames Tunnel is essential if we want to help protect and sustain the ecosystems within the Thames Tideway and improve the ecology of the capital’s river. Without the construction of the Thames Tunnel we are likely to see more frequent CSO discharges, resulting in further environmental and ecological damage, as well as increased litter. Less sewage entering the River Thames and being captured by the Thames Tunnel will help ensure: • The UK will continue to meet its commitments under the UWWTD and the WFD. • Existing fish populations will be sustainable in the long term, leading to benefits for wildlife and the many anglers that use the Thames Tideway. • The potential for increased biodiversity and a greater abundance of fish will be realised, including sensitive species and species of conservation interest such as shad, smelt, eels, and river and sea lamprey.

• The communities of fish and invertebrates in the Thames Tideway will be more balanced, with a greater number of species, particularly in the vicinity of the CSOs. This could have benefits for the bird populations that feed off them. Biologically dead for many years, there is now a much greater diversity of wildlife in the river that needs to be protected from the increasingly frequent overflows of sewage into the river. The proposed Thames Tunnel will help to ensure that the cleaning up of the River Thames and improvements to water quality continues.

Construction of the Thames Tunnel A comprehensive Environment Impact Assessment, currently being undertaken for the Thames Tunnel project, will ensure that all of the possible impacts on the Thames Tideway and its wildlife have been identified. Measures have been incorporated into the design of the scheme to ensure the least disruption to ecosystems within the Thames Tideway including: • control measures to prevent spills of chemicals or silty water into the river during construction • restrictions on dredging and piling to protect fish spawning areas • use of specialist piling techniques to minimise under water noise and vibration • careful consideration of lighting to minimise disturbance to aquatic wildlife • provision of timber fenders on permanent foreshore structures to promote aquatic habitats.


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

A great number of the WWT’s London’s Wetland Centre’s waterfowl utilise the tidal Thames. As well as a ‘superhighway’ for migratory birds in the city centre, the River Thames is regularly used at low tide by wildfowl such as Common Teal and Mallard. Fish eating birds also occur on the tidal Thames such as the Grey Heron, Cormorant and Great Crested Grebe. The water the London Wetland Centre receives is of a reasonable quality; but does contain quite high levels of phosphate. The Thames Tunnel would prevent major CSO discharges into the tidal Thames improving the quality of the water, for both fish species and the many water and wildfowl that live in and around the Thames Tideway. Carrie Hume Head of Conservation Policy Wildfowl & Wetlands Trust (WWT)


The Thames Tunnel is essential to help protect and sustain the ecosystems within the Thames Tideway and improve the ecology of the capital’s river for the future.

For further information see our website: www.thamestunnelconsultation.co.uk or call us on 0800 0721 086