Energy and Climate Change CommitteeWritten evidence submitted by the Severn Rivers Trust (SEV57)
Introduction
1. The Severn Rivers Trust is pleased to be able to submit evidence to the Energy and Climate Change Committee Select Committee inquiry into the proposal for a Severn Barrage.
2. The Severn Rivers Trust is an independent environmental charity established to secure the preservation, protection, development and improvement of the rivers, streams, watercourses and water impoundments in the Severn catchment and to advance the education of the public in the management of water and the wider environment.
General Comments
1. We attach great value to the Severn Estuary for its international importance for wildlife, and for the economic and social benefits that this provides. The Severn estuary has the second highest tidal range on the planet and is rightly protected under the European Habitats directive and as such should be preserved for present and future generations.
2. The Severn Rivers Trust did contribute to the Department for Energy and Climate Change (DECC) feasibility study which concluded with a public consultation in April 2009.
3. At that time the Severn Rivers Trust supported the report produced by the Wildlife Trusts, Energy at any price? which coincided with the public consultation: http://www.wildlifetrusts.org/publications. The report examined each of the five short-listed options in turn. The Severn Rivers Trust and Wildlife Trusts did not support any of these five options, and believe that a barrage from Cardiff to Weston would have a devastating impact. 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. The Severn Rivers Trust believes that they should still be researched further.
4. Whilst nothing more has been heard about those more innovative technologies, Hafren Power has come forward with a proposal—yet we have not seen a detailed technical proposal to date. As such this evidence is based on the work which we undertook during the DECC feasibility study. Without detailed information on the Hafren Power proposal it is very difficult to assess the impacts and make informed comments. However we remain deeply sceptical that a shore-to shore barrage on the scale of that envisaged can be delivered without unacceptable damage to the Severn Estuary, its wildlife and heritage, and the tourism, recreational and commercial activity that this supports.
Specific Questions
What contribution could the Cardiff-Weston Barrage make to UK energy security and climate change objectives?
1. The Severn Rivers Trust supports the UK’s targets to reduce greenhouse gas emissions and the Government’s ambitions to tackle climate change and increase the proportion of overall energy generated from renewable sources. We share the sense of urgency in deploying and developing solutions to move the UK towards a low carbon society. However, deployment of large-scale renewables cannot be at the expense of our wildlife, habitats or the environment; it is essential that the right technologies are developed in the right place.
2. The two year feasibility study carried out by the DECC demonstrated that whilst the Cardiff-Weston barrage would have the highest energy production 8.64 GW, with CO2 savings per year of 7.2mt and cost per unit of energy 12.9p/kWh, it also had the greatest overall impact, with far more intertidal habitat loss than any other option. More than 95% of habitat within protected areas would be lost (20,000ha). The safe passage of fish species to all tributary rivers and downstream through the estuary would be impeded, leading to likely regional extinction of Atlantic salmon and Twaite Shad. In addition the migration of Eels would be adversely impacted, particularly in the early stages of their life cycle, which is in the main passive, therefore any obstruction or delay to their migration could have severe consequences to the Eels’ long term survival.
3. As such the proposed Cardiff-Weston barrage would fundamentally change the Severn’s ecology, affecting both people and wildlife.
4. We need to ensure that decisions made balance our energy needs against the Estuary’s ecological, recreational, social and cultural value. The Severn Rivers Trust believes that any development should respect the intricate natural processes which have developed here over millennia, and at present we do not believe that a Cardiff-Weston Barrage does this.
What risks and opportunities could it pose with regard to flooding in the Severn Estuary, and how might any risks be mitigated?
5. The Severn Rivers Trust believes that there are far more risks associated with the Cardiff-Weston barrage than opportunities, especially with regard to flooding. Far from bringing benefits, a tidal barrage is likely to make our coast less resilient against the effects of sea level rise. In addition to the issue of overland flooding the possibility of ingress of sea water into ground water aquifers on both sides of the estuary, resulting in contamination of freshwater has, as far as we can establish, not been considered in detail. Therefore further research is urgently required into this issue.
6. There has been much talk that a barrage is likely to bring major flood relief benefits due to the reduction in tidal flow and therefore the amount of sediment in the water, which will lead to increased sediment deposition on foreshores. However, lessons arising from both the surge-tide barrage across the eastern Scheldt in The Netherlands and the tidal power barrage at Annapolis Royal in Canada, both silty estuaries like the Severn, have resulted in foreshore erosion, rather than deposition. These examples show how removal of energy from coastlines has unexpected consequences potentially resulting in flood defences being undermined in the long-term as foreshores become less muddy rather than muddier.
7. The ecology and the shape of the Estuary are constantly changing due to the complex interchange of water and sediment. This regime distinguishes it from other estuaries and influences the whole ecosystem. Technology that extracts some of this energy will inevitably affect the way the coast develops. The main impact will be to reduce sediment supply to the coast and to increase sedimentation in the sub tidal area. This means that putting any structure in the Estuary will lead to some degree of erosion. In the long-term this process has important implications for flood defences and other coastal structures such as ports, railway lines and roads.
What risks and opportunities could it pose to wildlife and habitat in the Severn Estuary, and how might any risks be mitigated?
8. The Severn Estuary is an extensive site of international importance for coastal and marine biodiversity, with much of the Estuary designated as a Site of Special Scientific Interest, a Ramsar site (a wetland of international importance), a Special Protection Area and a Special Area of Conservation. Furthermore there are 228 Wildlife Trust nature reserves in the region, totalling 3,450ha, and 17 Living Landscape schemes covering 372,700ha, or 1,400 square miles. Up to 16 reserves would be affected by construction of a barrage, including the destruction of part of the Penarth Coast SSSI, and with it The Lavernock nature reserve, if the proposal was on a similar alignment to the original Cardiff-Weston barrage proposal.
9. It is one of the major estuarine sites for unique invertebrate species, providing irreplaceable habitat for some 69,000 overwintering waders and wildfowl, over one hundred species of fish and a nursery ground for 10 species of commercial fish. Its extensive saltmarsh, mudflats and sub tidal reefs are important features in their own right, with some estimated 10 million tonnes of sediment carried up and down the Estuary on a spring tide—it is the dynamic nature of the Estuary which not only makes it unique but also presents the opportunity to harness energy from the second largest tidal range in the world.
10. In terms of risks and opportunities for wildlife and habitat in the Estuary, the Cardiff-Weston barrage is likely to have significant impacts on this internationally important Estuary and so once more The Severn Rivers Trust believes this poses risks on an unprecedented scale. We do not believe that there are opportunities for wildlife and habitat by extracting energy from the system.
11. With reduced sediment mobilisation the water column will no longer provide sediment onto the mudflats and sand flats resulting in the loss of these habitats. This would have a profound effect on the Severn Estuary’s wildlife, including its internationally important bird and fish populations. It is not merely loss of habitat which is represented here, but the total disruption to the ecosystem on which many species depend.
12. The huge productivity within the mudflats of the Severn makes it a winter refuge for white-fronted geese, and thousands of widgeon, teal and pintail, which migrate from Russia. It is also an essential refuelling stop of long distance migrants that winter in sub-Saharan Africa and pass through the UK twice in spring and autumn. Adults and young birds need to put on half their body weight in fat to enable them to make these journeys, therefore biologically rich estuaries like the Severn are vital. A reduction in the area available due to the development of a Cardiff-Weston barrage would have significant impacts on bird numbers and is likely to result in a significant adverse effect on site integrity.
13. The survival of fish populations would also be severely threatened. Fish passage to all tributary rivers within the Severn Estuary, including the improving Wye, and the Usk Special Areas of Conservation (SAC) would be hindered. Salmon for example enter the Estuary system and swim up and return on average 15–20 times before finally making their way upstream. This could mean that a salmon would have to try and pass through the turbines 15–20 times, increasing the risk of mortality. This would have a catastrophic impact on populations of migratory fish and lead to severe decline or local extinction of species such as genetically distinct Atlantic salmon and Twaite Shad. Loss of important nursery and feeding areas could also result. Juvenile Eels without the ability to swim during this stage of the life cycle drift across the Atlantic for between 21 and 28 months and on reaching the estuary continue their migration almost entirely by means of the incoming tide in order to reach the tributaries and the freshwater environment they require to mature into adulthood before returning to sea to spawn. Any impedance to migration could have a catastrophic impact on their survival.
14. The Severn Rivers Trust believes it would be almost impossible to mitigate all the risks associated with a full barrage across the Severn. The DECC feasibility describes the chance of finding like-for-like habitat elsewhere as “impossible”. Any habitat creation, it admits, would have to be on an “unprecedented” scale.
What lessons can be learned from the successful development of La Rance tidal barrage in France and other tidal power projects?
15. When assessing the potential environmental impacts of a Severn barrage it is important that comparisons and lessons learnt are made using examples from estuaries that are similar to the Severn. As detailed above (in relation to flood risk) one of the key environmental considerations is the alteration in geomorphology in the Estuary and as such comparisons needs to be made with similar silty estuaries. Research undertaken during the DECC feasibility study suggests that La Rance is not a suitable comparator for considering possible changes on the Severn. La Rance lies on a rocky coast and its form is largely determined by hard geology. Thus, its overall form is unlikely to change greatly, even though localised changes in sedimentation and erosion will occur. In addition its sediment was mainly sandy—unlike the Severn which is a sink for fine sediments in various locations.
16. The La Rance scheme was built as a pilot for a proposed much larger tidal power scheme which was cancelled due to the devastating impact the La Rance scheme has had on its own estuary and adjacent marine environment during its construction and post build. Furthermore the poor performance and severe adverse environmental impact of the La Rance scheme is the source of ongoing controversy. The construction of a storm surge barrage has had, and continues to have significant impacts on the Estuary ecosystem. There has been significant and ongoing coastal erosion, as predicted for the Severn. This has resulted in loss of important habitat, expected loss of bird populations over the next 50 years as a result, and ongoing cost to the taxpayer to mitigate the increased flood risk.
Are the proposals in breach of EU legislation, and if so how will this be addressed?
17. The DECC feasibility study considered a short-list of five options, which were assessed as part of the study. As we are yet to see technical proposals from any private developer, or otherwise from Government, it is impossible to comment at this stage whether such a proposal is in breach of EU legislation although it is highly likely to do so. We acknowledge that the proposal from Hafren Power is an ebb/flow, low-head barrage to sit across the Cardiff-Weston alignment, however, given the likely magnitude of impacts to European wildlife sites, including the Severn Estuary and its tributary rivers, and the low confidence in mitigation and compensation measures of the original Cardiff-Weston barrage, we consider it highly doubtful that the proposal could comply with the European Directives.
18. Legal advice which was attained jointly with WWF-UK, the Wildfowl and Wetlands Trust, and the Wye and Usk Foundation in 2010 stated “If compensation cannot be achieved in a broadly like-for-like manner, as conventionally required under the Directive, then the proposals for the barrage as they stand cannot be lawfully fulfilled, because they cannot show the compensatory measures necessitated by Art.6.4 can be attained”. (In reference to the Birds and Habitats Directive).
19. As we have seen no proposal of the detail, we cannot give evidence or comment upon how the company propose to address this. However the scale of the impacts of a proposed barrage on the estuary (including geomorphology, hydrology, sea level, habitats and species, landscape and amenity value) must be subject to robust and peer-reviewed analysis. This will require not only an understanding of the impacts of the proposed development, but also of the structure, function, and ecology of the estuary, and is a prerequisite for the identification of potential mitigation and compensation measures.
Are any other proposals for tidal power projects in the Severn Estuary currently under consideration?
20. There are proposals for a tidal lagoon development in the Bristol Channel between Port Talbot and Swansea, the details of which are expected to be published in spring 2013.
21. We understand that Parsons Brinckerhoff also intend to present their proposal for the Stepping Stones lagoon in Bristol on the 11 and 12 December 2012.
December 2012