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Home , Beachley, Minehead, Severn estuary

Energy at any price

Valuing the Severn as an international asset

Protecting Wildlife for the Future , eight miles up from the proposed - Weston barrage. Intertidal habitat like this is the basis of the entire ecosystem, and contributes to other ecosystems in the UK and abroad

Choose wisely The right tidal power solution must consider – and understand – the Estuary system as a whole. The Wildlife Trusts Wildlife The

te vast tidal range of the Severn Now, quite suddenly, the need to reduce our Estuary makes it one of the great greenhouse gas emissions has been natural wonders of the world. It recognised. What remains much less well has unique wildlife habitats recognised is the value of wildlife to people, shaped by the beautiful winding and the urgency to restore our landscapes so riversT that run down from the Welsh hills to that they are resilient to the impacts of climate meet the sea of the Channel. change. The great risk is that the debate The Estuary provides a haven for the young becomes one dimensional. This is why it is so of our commercial fish stocks, it is a means of vital that we make the right decision about transport and trade, it is the site of many harnessing the Severn: to capture the power of recreational pursuits and by its very nature it the water without blocking its full flow. In this brings enjoyment to people of all ages. It is all way fish can still move and the tides can still these things and more, and a glance through ebb and flow for miles, creating huge mud flats this report will provide the first-hand accounts and marshes. of what the Estuary means to people who live The Department for Energy and Climate their lives by its tides and nature. Change (DECC) Severn Tidal Power The tidal range also makes it a huge Feasibility Study in 2007 considered five potential source of energy. Proposals to use short-listed options – this report looks at each this potential, and concerns about the possible in turn. The list included three barrages and impacts on the Estuary ecosystem, go back two lagoons which all look to impound decades. So do warnings about the threat of seawater at high tide, letting it out again on the climate change. low tide. The Wildlife Trusts do not support any

2 The Wildlife Trusts’ report In this report

What could happen to the Estuary? pp4/5

What’s at risk? pp6-15 Choose wisely

How the Estuary works, pp16-19

of these five options, and believe that a Scheme. Now private investors are barrage from Cardiff to Weston would have a considering the options for harnessing the devastating impact. power of the Severn, but the same principles More positively, there were three more still need to apply. innovative options, known as the Severn For decades, successive Governments Embryonic Technologies Scheme (SETS). ignored the pleas of environmentalists to These include a reef, fence and a new kind of address climate change. Now surely they must barrage. None would block the flow of the tide listen to us and ensure the right means of in such a devastating way. They therefore hold harnessing a fantastic resource without losing the most promise for the best technology this wonder of the world. The tidal power options, pp20-21 possible, with the least impact. The Wildlife Stephanie Hilborne Trusts believe they must be researched further. Chief executive, The Wildlife Trusts The Severn Tidal Power Feasibility Study concluded in 2009 that there wasn’t a strategic case for public investment in a Severn Tidal We believe more innovative options promise the best technology

possible, with the least impact What’s the best way ahead? pp22/23

The Wildlife Trusts’ Severn Estuary report 3 A flock of curlew, fresh in from Russia, cross Bay National Nature Reserve as they wait for rich pickings at low tide

What could happen to the Estuary? The second biggest tidal range in the world makes it a strong candidate to supply renewable energy.

he idea of harnessing the tidal through turbines to generate electricity. Some Each of these schemes (see p20) comes power of the Severn Estuary is options have the potential to generate energy with different costs, environmental impacts and more than 100 years old, but it on the incoming tide too. energy outputs. Depending on the decisions has never looked closer to The Government also invested in the made, harnessing the Estuary’s tidal energy becoming reality than today. Under Severn Embryonic Technologies Scheme could fundamentally change its ecology, pressureT to decarbonise energy production, (SETS). The SETS projects are less affecting both people and wildlife. the UK Government considered a shortlist of technically proven, but may create less It’s no exaggeration to say that the Severn five options in 2007. environmental impact. They include a proposal Estuary is an irreplaceable part of the UK’s These were three barrages (the huge for a tidal fence (essentially a line of marine natural heritage. It boasts some of Europe’s Cardiff- Weston; the smaller Shoots Barrage; turbines) and a tidal reef (using the rise and fall finest natural habitats and wildlife, recognised and the even smaller Barrage) and of the tides to generate power). There’s also a and protected by international, European and two lagoons ( and Fleming). new kind of barrage, the Spectral Marine UK laws and agreements. For all five, the basic idea is the same: to build Energy Converter, that uses pillars rather than It’s not just the sheer size of the place which up a head of water at high tide behind a a solid wall, thus allowing the water to flow in makes it unique. Its fast-flowing, silty water retaining wall, and then let out the water and out of the Estuary relatively freely. has, over thousands of years, created an

4 The Wildlife Trusts’ Severn Estuary report David Woodfall

Where are the proposed sites?

Wildlife Trust reserve SHORTLIST options 1. Beachley Barrage Wildlife Trust 2. Shoots barrage Living Landscape Scheme 3. Cardiff-Weston barrage SACs, SPAs and Ramsar sites 4. Fleming lagoon (darker blue indicates multiple 5. Bridgwater Bay lagoon designations) SETS  SCHEMES Heritage Coast 6. Tidal reef 7. Tidal fence (location a or b) Proposed scheme location 8. SMEC (possibly a or b) n Bristol

n Weston-super-Mare ecosystem unlike any other in the UK. Its workings are still only partly understood, (see pages 16-19), but that brown water and sticky n mud are so productive that birds and fish National Park Charlotte Owen migrate thousands of miles to feed there. n Barnstaple The Government’s job is to balance our energy needs against the Estuary’s ecological, recreational, social and cultural value. The The Estuary is heavily protected by UK, affected by construction of a barrage. Much of Wildlife Trusts believe that any development international and European law. There are 228 the Estuary is designated as a Site of Special should respect the intricate natural processes Wildlife Trust nature reserves in the region, Scientific Interest, a Ramsar site (a wetland of which have developed here over millennia. totalling 3,450ha, and 17 Living Landscape international importance), a Special Protection schemes covering 372,700ha, or 1,400 Area and a Special Area of Conservation. square miles. Up to 16 reserves would be

The Wildlife Trusts’ Severn Estuary report 5 AT RISK

Blocking the Estuary would dramatically alter the way the tides move silt around, leading to unexpected consequences

The coast Far from bringing benefits, a tidal barrage is likely to make our coast less resilient against the effects of sea level rise

roposals for a barrage across the These arguments are very attractive, but regime distinguishes it from other Estuary have been accompanied they overlook the lessons arising from relevant and influences the whole ecosystem. by considerable positive spin. The schemes elsewhere. Both the surge-tide Technology that extracts some of this energy Estuary is claimed to have little barrage across the eastern Schelde in The will inevitably affect the way the coast ecological value, and local Netherlands and the tidal power barrage at develops. The main impact will be to reduce communitiesP have been convinced that there Annapolis Royal in Canada have resulted in sediment supply to the coast and to increase will also be major flood relief benefits. But are foreshore erosion, rather than deposition. sedimentation in the subtidal area. This means these assertions true? Evidence from barrages These examples show how removal of energy that putting any structure in the Estuary will in silty estuaries in The Netherlands and from coastlines has unexpected lead to some degree of erosion. Canada suggests otherwise. consequences. Flood defences are likely to be In the long term this process has important It is argued that reducing tidal flow, and undermined in the long term and waterfowl implications for flood defences and other therefore the amount of sediment in the water, populations can be expected to decline further, coastal structures such as ports, railway lines will lead to increased sediment deposition on as foreshores become less muddy rather than and roads. Far from bringing flood defence foreshores. This deposition, combined with muddier. benefits, tidal energy structures are likely to micro-algae blooming in the clearer water, is The ecology and the shape of the Estuary make our coast less resilient in the face of sea also presented as the solution to feeding are constantly changing due to the complex level rise. displaced waterfowl. interchange of water and sediment. This Roger Morris consultant

6 The Wildlife Trusts’ Severn Estuary report In the long term, extracting energy from the Estuary has implications for ports, railway lines and roads David Woodfall

The end of archaeology in the Estuary? The Estuary’s huge deposits of mud and silt sediments is possible due to the natural Figure 1 - Examples of archaeological sites and fi nds in the Severn region The Estuary’s are laid down upon one another and waves and tides eroding small cliffs, allowing N interwoven made inland that may be interleaved with peat bands very much like archaeologists access to the pages of time. connected to the overall layers of storysilt of the Severn, and that Sites and Monument Records/Historic Environment The boat was recovered over a six week period and is Records only reveal the known picture. Furthermore, it The Newport Ship being conserved in Newport Museum. The finds indicated highlights the correct way of dealing with unexpected small the rings of a tree. Every layer represents a However, if the Estuary’s natural energy that this boat had beenand abandoned in a peattidal region of findshave made outside the planning system. If these coins the in the C4th AD and had probably been had been found during development work, and outside Caerleon Barracks reused as a landing stage. The boat would have been the remit of a watching brief or evaluation, site developers ideally suited to travelling along the Severn and also would still have a duty to report the finding of the objects to serves to indicate thatrevealed the Caldicot levels were subject the local planning authority/Finds Liaison Officer. particular episode in our past, from the were to be blocked, foreshore erosion may Thornbury to tidal flow and thus navigable. The recovery of the boat through conditions applied to planning permissions, careful archaeological monitoring and co-operation with The Goddess developers was exemplaryevidence and allowed this important of A hundred years ago, a 14.6cm bronze statuette was discovery to be recovered. discovered at Aust, in South at the foot fossilised footprints of Stone Age hunter- initially increase and as water levels upstream Thornbury Coin Hoard of the cliff near where the first now stands. See the ‘The Barland’s Farm Romano-Celtic Boat’ by Nigel Nayling and Seán McGrailhuman for further details on this find. travel,This female statue with glass eyes and a head-dress was of a style that led to it being published as a 3rd Century At both of these sites, and initial archaeological assessment BC import from Spain. It was believed to have arrived in resulted in archaeological monitoring during development. the region perhaps through trade up the Severn. Other gatherers walking across the muddy Estuary, of a barrage would be raised – caused by the Important discoveries then triggered full-scale excavation settlementsauthorities now believe that, the statuette may be late Iron to enable these internationally important remains to be Age or Roman in date, but is of local origin and represents recovered. a fertility goddess. This may be a representation of Sulis – a goddess equated with Minerva in the Romanised The Thornburyand Coin hoard – trade through the complex wooden trackways deposition of sediments subtidally – these adoption of local divinities an unexpected find. (see Sulis-Minerva at Bath). A find of this quality The Aust Goddess In 2004 a huge hoard of Late Roman coins was found emphasizes the importance by Ken Allen whilstdating digging a garden pond in Thornbury, back as of the region. The possibility . The hoard, of some 15-20,000 of a link with Spain is exciting, built up until the Bronze Age, to the Roman- layers would become submerged and coins was reported to Bristol City Museum and to the Finds although, even if the artefact Liaison Officer for Gloucestershire and Avon. Despite the far as theis local, there are enough fact that none of the coins were gold, they were deemed finds from Spain and France to be treasure under the 1996 Treasure Act as there were to amply illustrate that there more than ten of them and they were over 300 years old. built ports along the coast that were further drowned. This wonderful window to the past were long standing trading The site was unknownStone until this discovery and the Afinder ge. links with Atlantic Europe. behaved in an exemplary fashion by reporting the find so promptly. These coins, some of which dated to the reign of Constantine the Great (AD 307-337), were found in a developed through Medieval times up until would be shut tight. parish that includesMuch the River Severn and might indicatemore Roman trade up this route. Their deposition perhaps hints The Barland’s Farm Boat Trade Routes to and from the Severn at the quick devaluation of this type of coinage although their hasty burial, perhaps to avoid being seized by raiders A facsimilie of the could be Aust Goddess moving up the river, is an outside possibility. This find This map is reproduced from material with the permission of Ordnance Survey on behalf of the Controller of Her Majesty’s Stationery Offi ce Crown copyright. Unauthorised reproduction infringes Crown copyright and may lead to Image courtesy of Bristol City Museum prosecution or civil proceedings. South Gloucestershire Council Licence No 100023410, 2006 the present day. Uncovering this rich Professor Simon Haslett amply illustrates the fact that there are still discoveries and Art Gallery 4 9 treasure-house of history within the University of , Newport discovered

The Wildlife Trusts’ Severn Estuary report 7 AT RISK The Bore The Estuary is exceptional for fishing and birdwatching. And the is one of the UK’s greatest natural phenomena

s dawn breaks over rumble, the sound intensifies until by the time Over the ages the Bore has become part of Gloucestershire a strange scene the Severn Bore is visible, rounding the final the river’s ecosystem. But it’s also important to unfolds in a pub car park. This is bend, it sounds like an approaching train. people. Many businesses benefit from the on the banks of the The surfers clamber onto their boards. For tourism the Bore creates, whilst salmon and Severn, but it is a sight more some, it will be the longest ride of their lives; a elver fishermen rely on it for their livelihood. Acommonly associated with the beaches of few have managed over six miles. The The Bore is also incredibly important to the and Cornwall. Men and women are spectators are about to witness one of the surfers that ride it. As well as the hundreds of donning wetsuits, waxing their surfboards and UK’s most spectacular natural phenomena. coastal surfers who come for the largest tides entering the waters of the river. The Bore is born in the funnel-shaped, there is a tight-knit group who organise their The opposite bank is already thronged with strongly tidal Estuary. The massive incoming lives around the lunar cycle, so that they can people holding video cameras and binoculars. tide is squeezed into a smaller and smaller be in the river the next time the Bore rounds Everyone is gazing downstream, straining to space until the water has no choice but to pile that bend. But a device that reduces the river’s be the first to glimpse the oncoming tide. But up, forming a wave that travels upstream for tidal range would eliminate all that. it’s their ears that sense it first. Initially a dull more than 30 miles, at speeds of up to 15mph. Dave Butterton, Bore surfer

8 The Wildlife Trusts’ Severn Estuary report About 80 times a year the incoming tide and the Estuary’s funnel shape create the Severn Bore – and the chance to surf for miles in fresh water The Bore Andrew Mawby David Woodfall Mike Lane David Chapman

The Estuary provides many forms of recreation. Its It’s quite possible to spend a lifetime birdwatching More than 100 species of fish are found in the river landscape brings walkers and sightseers from all in the Estuary (see page 14). Hundreds of species, Severn and its Estuary. Some of the most sought- over Wales, the South West and the Midlands some from half way round the world, pass through after species migrate into its eight tributary rivers

The Wildlife Trusts’ Severn Estuary report 9 AT RISK

Atlantic salmon hatch in clear, clean gravel beds upstream before travelling downriver to the ocean to feed and grow. Two or three years later, they’ll return to breed in the same place

Our fish stocks It’s not just salmon. Eel, shad, lamprey and sea trout must all move between fresh and salt water to survive

Collecting fish and cleaning off debris is an all-weather job

igel Mott and Dave Merrett are Nigel. “It was the first time it had been done on not your typical retired industrial this site since 1861, though there are about 20 chemist or civil engineer. They other fishing stations in the Estuary. We are modern day hunter- installed the stainless steel baskets in 1985, gatherers, fishing the river day with pilings driven into a concrete base. Nand night using ‘putchers’ – rows of conical “When the salmon enter the Estuary baskets fixed to the river bed to trap unwary system, they swim up and return on average salmon. Although the baskets use modern-day 15-20 times before finally working their way stainless steel, their design and function are no upriver. Higher temperatures and pollutant different from the wicker structures that have run-off can reduce the likelihood that the caught salmon here sustainably since the Iron salmon will head upstream.” Age. Maintaining the fishery takes three or four “We established the fishery here in 1975 hours twice a day, starting an hour after high with a National Rivers Authority licence,” says water, clearing the 650 baskets of seaweed,

10 The Wildlife Trusts’ Severn Estuary report If the salmon swam through the turbines it would increase the risk of mortality on an already depleted stock

Our fish stocks FLPA/Foto Natura Stock

rubbish and (occasionally) fish. Salmon fishing might sound romantic, but it is hard work. Both men support the need to move towards non-fossil energy generation, but are nervous of the effects of turbines on migratory fish. “If the salmon swam straight up the Estuary and entered fresh water straight away, then many might survive,” Nigel believes. “But if they swam through turbines a number of Around 20 times it would increase the risk of mortality to fisheries in the an already depleted stock. Our fishing would Estuary sell locally-caught be devastated in quite a short time.” wild salmon

As would the sport of thousands of game Woodfall David fishermen along the Severn and its tributaries.

The Wildlife Trusts’ Severn Estuary report 11 AT RISK

In this picture alone there are countless millions of animals just below the surface – waiting to eat, or be eaten

The life source It’s easy to overlook what mudflats really are. In fact they’re the Estuary’s power source, swarming with life, and sustaining... us!

ig down an inch, scrape up a water. Let it settle out for a few minutes, and (microscopic plants) and algae. And that’s why square metre of estuarine mud soon you’ll notice mysterious animations: countless visiting or resident birds frequent the and you’ll be holding the calorific wriggling and writhing bodies, limbs and gills all exposed flats betwixt the tides, and why these content of 13 Mars bars. So etch their hieroglyphics in the silt. estuarine habitats are a vital nursery ground someone told me once and, From the more obvious worms of the rag for many fish – including commercially Dwhile I’m not sure it’s true, it certainly goes and lug variety (I think they look like miniature valuable ones. some way to pointing out just how important Chinese dragon dancers) to small clams, that mud is! Corophium shrimp and my favourite (and that You see, mud is all the best bits of the land, of the shelduck) the miniscule laver spire shell. donated via our rivers and then dropping out All these creatures add up to a sum greater of suspension as the water flow slows. This than its parts. Nick Baker is a nutrient-rich soup then feeds the system The mud may not look like much from a zoologist best known for his wildlife which we all need – whether we realise it or human perspective, just a monotonous plain. It programmes with the not. is actually one of the most productive habitats BBC, Channel 5, If you’re a doubter, you need to (safely) on Earth, thanks to the activities of the above Granada and Animal Planet. He is also a access some of the glorious stuff – to scoop up characters, plus the even smaller plant lives vice president of The a cupful and sort through it in a tray of sea being lived out in there – the diatoms Wildlife Trusts

12 The Wildlife Trusts’ Severn Estuary report A mudflat may look like a monotonous plain, but it is actually one of the most productive habitats on Earth

From flotsam to protein A pile of estuarine debris: recently deceased crab mixed up with freshwater reed stems. It’ll all be eaten in the end by the mud-dwelling worms, shellfish and prawns...... who in turn must take their chances with the feathered predators who want David Woodfall

David Slater to eat them. High tide provides no relief: it just means the fish are moving in where the birds left off

The Wildlife Trusts’ Severn Estuary report 13 AT RISK

Refuge for birds They arrive by the thousand, from Canada, Africa and Russia. And they come to the Estuary for food, rest and shelter

have watched birds on the come ever since, though like the whitefronts within a few days the adults leave, arriving on Gloucestershire sector of the Severn their numbers have decreased. the Severn in late July or August before Estuary since I was ten, when I made the The Severn is also an essential refuelling moving on to places such as the Banc d’Aguin 50-mile round trip by bicycle every stop for long distance migrants that winter in in Mauritania, or even South Africa. Their weekend. Some early highlights arouse sub-Saharan Africa and pass through the UK young find their own way a month or so later. fondI memories: that bunting in October twice: in spring, on their way to Arctic breeding Quite apart from the navigational feat, the 1953, or the red-throated diver at high tide in grounds in Canada and the Russian tundra; physiological performance is exceptional; both January 1956. But it’s the regular visitors which then again in early autumn on their way back. young and adults put on half their body weight leave the lasting impression. Waders like bar-tailed godwit or little stint use in fat to enable them to make these flights. For example, Slimbridge is a winter refuge the short tundra summer to hatch their young; They use up this extra fat in migration, so for white-fronted geese and thousands of wigeon, teal and pintail, which migrate every year from Russian breeding grounds to the The adults leave their young in terminus at the westernmost end of their 3,000 mile flyway. In the cold winter of 1962 they the Arctic, arriving on the Severn were joined by a massive arrival of Russian Bewick’s swans, which have continued to in July before moving on to Africa

14 The Wildlife Trusts’ Severn Estuary report Like many visiting waders, knot gather in the Estuary in huge flocks

Refuge for birds

Besides the huge flocks, the rarities. This is a pomarine skua, pausing half way between the far North and the tropics stops in biologically rich estuaries are vital. Then, having wintered in warmer climes, they are back on the Estuary the following spring, David Slater together with other waders like whimbrel which gather in the western UK to refuel, en route to their Icelandic nesting grounds. In cold snaps the Estuary’s brackish water remains ice free, attracting birds from inland sites like the Levels or the Severn Vale. Waders such as lapwing or golden plover, together with ducks from riverside marshes, flock to the Estuary at these times. In every way, then, the Severn Estuary is a bird site for all . Mike Smart, Trustee Gloucestershire Wildlife Trust

The Wildlife Trusts’ Severn Estuary report 15 How the Estuary ecosystem works It all begins with washed-in organic debris. Then the mud dwellers get to work The Severn Estuary is a hugely productive With fast, silt-laden currents in the central place, but that productivity isn’t driven directly channel, most of the predation happens in the by green plants and the sun. Instead the intertidal zone. The fish grab the worms and Estuary acts like a gigantic reprocessing plant, shellfish at high tide, with the prawns and using as its raw material plankton and flotsam crustaceans hoovering up the bits; six hours washed in from the sea and tributary rivers, later it’s the birds’ turn. plus churned-up sand-dwelling microscopic Most of the Estuary’s ecology happens in The humble lugworm. plants. In the mud and silt of the intertidal zone the intertidal zone. Reduce its extent, and you Estuary mud and sand (between high and low tide), billions of lose most of that huge productivity, with contains relatively few invertebrates and bacteria convert this debris knock-on effects to ecosystems elsewhere. species, but in huge numbers into protein. Overleaf shows where they are.

ZONES CHARACTERISTICS HABITATS

Large tidal range Saltmarsh Large intertidal area Sandbanks l a Lots of suspended Mudflats rich in wildlife id material Rock and shingle TERT Nutrient rich shoreline habitats N OSED I OSED P EX David Woodfall The key feeding zone: birds at low tide, fish at high tide

The silty water looks lifeless but, Strong currents Low and high salinity as this salmon trap shows, is a water corridor and food supply Highly productive habitats Shallow sandbanks Silt laden currents Muddy seabed rich in wildlife

SUBMERGED Shallow water-churned seabed David Woodfall

16 The Wildlife Trusts’ Severn Estuary report Vital statistics of the Estuary ecosystem estimated tonnes of sediment carried up 10,000,000 and down the Estuary on a spring tide visiting birds, either sheltering from the Arctic winter or refuelling during 69,000 their spring/autumn migration between north and south hemispheres hectares of the Severn Estuary in total, 24,700 making it one of the largest in Europe hectares of mud and sand flats – 20,958 the fourth largest expanse in the UK years of sedimentation evidence in the Estuary – a 5,000 valuable geomorphological and archaeological history hectares of rock, boulder, mussel/cobble scars, 1,500 rocky pools and shingle hectares of salt marsh – 1,400 the largest expanse in the South West species of fish found 100+ in the Estuary species of commercial fish use the Estuary in their life cycle: herring, cod, 10 plaice, sole, whiting, blue whiting, hake, horse mackerel, ling and saithe

David Chapman

WILDLIFE Fish

Shellfish David Slater

Paul Naylor

Neil Hepworth Birds

Sand-dwelling Hans Hillewaert Algal and Sand-dwelling diatoms TURN THE plant communities Anson MacKay invertebrates David Slater PAGE FOR THE Crustaceans MAIN EFFECTS Mid-water Paul Naylor Plant plankton fish ON OTHER Paul Naylor Bottom-dwelling ECOSYSTEMS fish

Rick Park Animal plankton Other

Paul Hobson invertebrates Sand-dwelling David Chapman worms

Sea mammals Rick Park Florian Graner Nature PL David Chapman

The Wildlife Trusts’ Severn Estuary report 17 The global impact Birds and fish disperse the Estuary’s energy and productivity to ecosystems across the globe

The previous pages explain how the Estuary these movements year after year, and the generates very large amounts of biomass (the cumulative effect is astronomical. Without the sheer weight of living things), most of it from Severn’s effect as a stopover and refuel facility, the intertidal zone. for example, the Arctic tundra couldn’t support Because most of the Estuary’s predators so many migratory waders. Without its effect are highly mobile fish and birds, they as a huge fish nursery, the (and the effectively transport the energy and material beyond) could not support so they pick up in the mud to other places. This many salmon, sprats or mackerel. energy and material is carried in these animals’ This extreme interconnectedness is what body tissues and guts, and transmitted via makes altering the Severn’s intertidal habitat their participation in other ecosystems where so risky. Does the Estuary’s energy prize justify they feed, are fed on, and eventually die and severing these global wildlife links, with their decompose. Millions of fish and birds moving benefits to people which are not yet fully around is impressive enough, but they keep up understood?

Dispersal happens across the UK too

n Shrewsbury

River Severn

The Severn’s tributaries The rivers are fine habitats for resident and migratory fish which feed in (and pass through) the Estuary n Worcester The Gwent Levels Habitat for a huge diversity n Hereford of birds. Many are reliant on the Estuary’s mudflats for their source of food Ross-on-Wye n n

Newport n n Bristol Cardiff n n Weston-super-Mare The local effect Animal movements disperse large The The Levels and the River quantities of energy and material Parrett are excellent from the Severn Estuary to habitats for resident and neighbouring systems in the region. migratory birds, many of The key areas to benefit are the which feed in the Estuary rivers Parrett in Somerset, Usk in Wales, the Wye either side of the border, and the Gwent and Somerset Levels

18 The Wildlife Trusts’ Severn Estuary Report iStock Photo

Eels After maturing in fresh water, adults swim across the Atlantic to spawn and die in the Sargasso Sea. The larvae are thought to return on North Atlantic currents. Numbers of eels have declined hugely in recent years, for reasons which are not fully understood. Mike Lane

Little is known of the eel’s migration routes

Salmon Principal feeding grounds are north of the Faeroes; adults are at sea for up to four years. Most populations are in decline. The sea trout, another migrant, is thought to stay near the UK coast, as do the allis and twaite shad (the Severn shad is a genetically distinct species). Laurie Campbell

Reasons for salmon declines are complex

Birds With several dozen species and sub- populations involved, the routes shown here are hugely simplified. But essentially there are three sorts of bird migration through the Estuary. The spring passage from Africa, branching west to breeding grounds in Iceland and Greenland, or east to northern Europe and Russia. The return journey, from late June to October, by adults and young. The winter visitors, which don’t go further south than the Estuary, and return north in spring to breed. Colin Varndell

Bar-tailed godwits: 300 grams of pure energy

The Wildlife Trusts’ Severn Estuary Report 19 The options In the DECC Severn Tidal Power Feasibility Study there were five options on the shortlist, with three SETS options which needed further research. Here are their environmental, energetic and cost analyses.

hese were, and still are, some of In general the proposals create three adverse 2. Change the way sediment moves the choices facing the UK impacts, none of them well understood: around. Different erosion and deposition Government as it tackles our 1. Reduce upstream tidal range. This is patterns are likely to greatly alter the quality climate change targets. Each likely to depress the productivity of the and extent of marine habitats, and of the option will affect the Estuary’s mud-based food webs, affecting everything surrounding coast, but the Estuary’s physical protectedT species and habitats. However, The higher up the food chain – including people. processes remain largely unstudied. Wildlife Trusts believe the decision should be Estimates of intertidal habitat loss vary hugely, 3. Threaten populations of migratory fish. taken on the basis of least environmental from 2,800ha (Tidal Fence) to 20,000ha Estimates of what the impacts might be are damage and best cost effectiveness. (Cardiff-Weston barrage). hampered by a lack of baseline data.

Shortlisted Shortlisted By kind permission of Parsons Brinckerhoff By kind permission of Parsons Brinckerhoff

Beachley Barrage Shoots Barrage

Smallest barrage, lowest adverse Habitat loss 3500ha Habitat loss same or less than Fleming, Habitat loss 5000ha impact, but lowest energy potential too. % within protected area 100% but no fish passage to the upper % within protected area 100% Located above the Wye, so fish Claimed power 0.625 GW Severn and the Wye SAC. Wholly Claimed power 1.05 GW passage to SAC rivers still possible. Construction cost £2.3bn within the cSAC, SPA and Ramsar, so Construction costs £3.2bn Wholly within the cSAC, SPA and CO2 savings per year 0.7mt significant loss of habitat and CO2 savings per year 1.2mt Ramsar, so significant loss of habitat. Cost per unit of energy 12.6p/kWh disturbance during construction. Cost per unit of energy 10.4p/kWh

Shortlisted SETS option By kind permission of STFC © Evans Engineering, 2008 By kind permission of Parsons Brinckerhoff

Bridgwater Lagoon Tidal Reef

Extends across smaller proportion of Habitat loss 5000ha Least technically developed option, so Habitat loss 8600ha Estuary than Fleming Lagoon, so likely % within protected area 100% estimate for intertidal loss likely to be % within protected area 0% to have less impact on erosion and Claimed power 1.36 GW less accurate. Turbines likely to turn Claimed power 5 GW siltation. Impedes fish migration to Construction costs £3.8bn more slowly than in barrages and Construction costs £18.7-19.8bn Rivers Parrett, Cary and Brue. CO2 savings per year 1.1mt lagoons, posing a lower risk to fish. CO2 savings per year 5.6mt Relatively low carbon saving. Cost per unit of energy 13p/kWh Large footprint is outside cSAC. Cost per unit of energy 20.3p/kWh

20 The Wildlife Trusts’ Severn Estuary Report Despite these uncertainties the Cardiff- Weston Barrage would, without question, have Current proposals for the Severn by far the highest environmental impact. The The DECC Severn Tidal Power Feasibility study concluded in 2009 that there was not a smaller barrages and two lagoon schemes (in strategic case for public investment in a Severn Tidal scheme. Since then several private their various forms) would be likely to have an investment options for the Severn have been proposed. One of these from Hafren Power is a intermediate impact. The SETS options proposal for a full Cardiff to Weston barrage, likely to have a slightly lower impact than the (labelled in green below) would have the barrage proposed in the feasibility study. However, The Wildlife Trusts believe this proposed lowest impact. Cardiff-Weston barrage would fundamentally change the Severn’s ecology, affecting both The Government’s own environmental people and wildlife. report expresses low confidence in the A more innovative approach put forward by RegenSW looks at Energy: A possibility of minimising the impacts of a balanced technology approach, which outlines most of the known ideas for marine energy barrage or lagoon development, and in generation from the Bristol Channel/Severn Estuary system and proposes adopting a multi- creating compensatory habitat. In fact it technology approach. The Wildlife Trusts welcome the approach RegenSW advocates, which describes the chance of finding like-for-like could facilitate a better understanding of the impacts of tidal energy generation at much lower habitat elsewhere as ‘impossible’. Any habitat risk to the environment and wider communities. creation, it admits, would have to be on an ‘unprecedented’ scale. The Wildlife Trusts want to ensure the What the acronyms mean SAC = Special Area of Conservation  cSAC = candidate Special Area of Conservation chosen option will not be something that SPA = Special Protection Area  Ramsar = internationally important wetland society regrets in decades to come.

Shortlisted Shortlisted By kind permission of Parsons Brinckerhoff By kind permission of Parsons Brinckerhoff

Cardiff-Weston Barrage Fleming Lagoon

Highest energy and overall impact, with Habitat loss 20,000ha The longest structure, all of it in cSAC. Habitat loss 6500ha far more intertidal habitat loss than any % within protected area >95% Impacts to migratory fish and % within protected area 100% other option. Fish passage to all Claimed power 8.64 GW freshwater habitats likely to be less than Claimed power 1.36 GW tributary rivers impeded, leading to likely Construction costs £20.9bn barrages, but would greatly affect Construction costs £4bn regional extinction of Atlantic salmon CO2 savings per year 7.2mt erosion and sediment movements CO2 savings per year 1.0mt and twaite shad. Cost per unit of energy 12.9p/kWh aroundEco-friendly the wall. barrage application of the SpectralCost per Mari unit neof energy Energy Converter.15.5p/kWh

SETS option SETS option By kind permission of Verd Erg By kind permission of STFC

Tidal Fence Spectral Marine Energy Converter

Relatively low impact over a wide area. Habitat loss 2800ha A series of pillars supporting a Habitat loss not known Partial barrier and low turbine speed % within protected area 0% causeway road. Structures in the pillars % within protected area not known less harmful to migratory fish. Less Claimed power 1.2 GW use very high speed turbines to Claimed power not known SMEC Barrage Section is lowered into place between pre-driven sheet piling Construction costs £6.5-6.9bn Figure 5. Construction costs not known impact on siltation/erosion too, due to coffergenerate dams ontoelectricity.the pre -Tidalprepared flowterrace is only level foundation. Gaps around and underneath the constant flow. Large construction CO2 savings per year 1.4mt SMECpartly Barrageimpeded. Section Data are and then location grouted. Sectionsnot needCO2 only savings be joined per year at roadway not level, known as footprint, outside cSAC. Cost per unit of energy 22.72p/kWh moreyet available. fully determined in detailed design. Cost per unit of energy not known

The Wildlife Trusts’ Severn Estuary Report 21

Figure 6. Underwater view of SMEC Barrage Section being towed into final position, showing closed ends of each manifold section making it buoyant.

Page 4 of 10 CONFIDENTIAL and Proprietary to VerdErg Renewable Energy Ltd. 17th December 2009 What kind of a world do we want to live in? It is time to understand that we are part of nature, not outside of it

e are becoming more and apparent. We must therefore ensure that our That destruction would not only affect the more aware of the impacts environment is one that can adapt to these Estuary’s internationally recognised wildlife and which our everyday lives global changes, not decline under growing habitats. The shape and structure of the have on the environment pressure. For this to happen we need to create Estuary itself would change, and this could in which we find ourselves. both a Living Landscape and Living Seas have serious consequences for our flood WWe must now take the next step: to realise – our vision for the future. defences. Then there are the ‘silent’ impacts – that yes, we are part of our ecosystem – not We often think of renewable energy as those which will take time to become evident, some separate entity existing apart from the being environmentally-friendly. But if the wrong some of which we simply cannot foresee. fish, the birds, the worms and the mud. This decisions are taken in the Severn – the wrong The Wildlife Trusts believe that none of the understanding changes our idea of the world technology selected, in the wrong places – shortlisted options from the Severn Tidal we want to live in. Of course we need energy then renewable energy has the potential to Power Feasibility Study were cost effective, – and the Severn Estuary presents an exciting destroy all that we rely upon. and all five could destroy one of the most and all too tempting option to provide a large slice of the UK’s renewables. But we cannot view our energy needs in isolation from our It is self-defeating to view our environment. To do so could easily be self-defeating. Why should this be so? energy needs in isolation from As climate change takes hold, the changes in our environment are becoming ever more our natural environment

22 The Wildlife Trusts’ Severn Estuary Report David Slater

Starlings at sunset, second

prized natural resources in the country. We were, and remain interested in more innovative options which were on the table at the time - none proposed to block the flow of the tide in such a devastating way, and therefore held the most promise for the best technology possible, with the least impact. We have a moral and ethical obligation to ensure that the least environmentally damaging, most cost-effective option for generating energy in the Severn is selected. So we need to fully investigate all the options, to make sure that the technology is right for the job. Most of all we need to ensure that decisions we take now, in the face of climate change, are not ones that we will live to The Wildlife Trusts believe that a sustainable future can regret in years in come. only come from working Andrew Kerr with natural processes, not against them

The Wildlife Trusts’ Severn Estuary Report 23 What you can do

Email or write to your MP 1 Express your concerns about taking the right decision, for the Estuary and people alike. You can find out who your local MP is by visitingtheyworkforyou.com

Join our campaign 2 Keep an eye on wildlifetrusts.org for further news and developments, and specific details of how to help.

Volunteer 3 If you would like to give your time to help The Wildlife Trusts’ campaign, please contact your local Wildlife Trust (if you’re in Wales or the South West) or visit our volunteering pages on wildlifetrusts.org.

Enjoy the Estuary! 4 Visit your local Wildlife Trust’s reserves in the area, or simply get out and about in the natural wonder that is the Severn Estuary

Editor Rupert Paul. Layout editor Phil Long. Researcher Liz Walker. Project co-ordinator Dr Lissa Goodwin. Cover picture B Lea / Skyscan.co.uk. Back page picture David Woodfall. Copyright The Wildlife Trusts 2010. References: P5: Location of options based on Department for Energy and Climate Change (DECC) data. P16/17: Ecosystem flow information by Dr Rick Park, . Severn facts: British Geological Survey 1996; Dargie, 2000. P18/19: bird migration routes supplied by Mark Ward, RSPB. Salmon migration route: CEFAS, also Tony Andrews, Atlantic Salmon Trust, www.nasco.int/sas/salseamerge.htm. P20/21: Shortlisted and SETS option performance data from DECC report.