Severn Barrage

The Severn Estuary by G HorupThe Severn Estuary

The Wildlife Trusts support the Government’s ambitions to tackle climate change and increase the proportion of overall energy generated from renewable sources. However,it can not be at the expense of our wildlife and habitats; the right technologies must be developed in the right place.


In autumn 2007, John Hutton announced a two-year, multi-million pound feasibility study into tidal energy options for the Severn Estuary. In response to this in spring 2008, in partnership with other environmental NGOs we commissioned a report on the economics of a Severn Barrage – The Frontier Report.

In April 2009, the Strategic Environmental Assessment Steering Group for the Department of Energy and Climate Change (DECC) project examined a shortlist of five options;

  1. Cardiff Weston Barrage:
  2. Shoots Barrage
  3. Beachley Barrage
  4. Bridgwater Bay Lagoon
  5. Fleming Lagoon

At this time Westminster announced additional money (£0.5m) to speed the development of innovative proposals – two tidal fences and an alternative barrage design – all of which the Wildlife Trusts believed could offer less environmentally damaging options.

The Wildlife Trusts published the ‘Energy at any Cost’ report that explained these alternative options in addition to examining each of the five short-listed options in turn. The Wildlife Trusts do not support any of these five options, and believe that a barrage from Cardiff to Weston would have a devastating impact.

In 2010 the Government concluded that there was not a strategic case for public investment in tidal energy schemes at that time, but did not preclude a privately financed scheme coming forward.

The Wildlife

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. Up to 16 nature reserves would be affected by construction of a barrage, including the destruction of part of the Penarth Coast SSSI, and with it The Wildlife Trust Lavernock nature reserve, if the proposal was on a similar alignment to the original Cardiff-Weston barrage proposal.

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 subtidal 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.

The huge productivity within the mudflats of the Severn makes it a winter refuge for white-fronted geese, and thousands of wigeon, 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.

Fish passage to all tributary rivers begins within the Severn Estuary, including the improving Wye, and the Usk Special Areas of Conservation (SAC). Salmon for example enter the Estuary system and swim up and return on average 15 – 20 times before finally making their way upstream.

As such the proposed Cardiff-Weston barrage would fundamentally change the Severn’s ecology, affecting both people and wildlife. More than 95% of habitat within protected areas would be lost (20,000ha) Fish passage to all tributary rivers would be impeded, leading to likely regional extinction of Atlantic salmon and twaite shad.

In summary a Severn Barrage would be catastrophic for the wildlife of the Severn Estuary

Our Position

Destroying the Severn Estuary – arguably the eighth natural wonder of the world – would be a deadly sin. We need your support to protect this unique place

The Wildlife Trusts support 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 can not be at the expense of our wildlife and habitats; it is essential that the right technologies are developed in the right place. 

We need to ensure that decisions made balance our energy needs against the Estuary’s ecological, recreational, social and cultural value. The Wildlife Trusts believe that any development should respect the intricate natural processes which have developed here over millennia, at present we do not believe that a Cardiff-Weston Barrage does this.

Present Situation

On the 31st October 2012 the DECC announced a call for written evidence for their investigation into the proposed Cardiff-Weston Barrage. It will examine the potential for the project to deliver low-carbon electricity to the UK and the likely cost to consumers as well as the potential impacts on wildlife and local employment.

The Wildlife Trusts submitted a response to the Severn Select Committee inquiry on the proposals for a Severn Barrage on 30th November 2012.




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Energy_at_Any_price_TWT_Severn_Esturay_report_2010.pdf2.52 MB