Barriers to Fish Migration
Despite the 1975 Salmon and Freshwater Fisheries Act's (SAFFA) requirement not to block fish access, vast tracts of the Wye and Usk catchments have been barred to migrating fish. This included the Wye's two largest tributaries, the Lugg (1982) and the Monnow (1917). By 1995, 50% of the Wye catchment was blocked by debris dams, impassable weirs and crossing points. Our survey of the Usk in 2004 showed that 28% of the river system was blocked by man-made obstructions, in addition to a number of impassable natural falls.
The quantum of juvenile fish production is proportional the size and quality of available habitat and that ultimately determines the size of the returning salmon run. In addition, barriers isolate fish populations so that when pollution or catastrophic natural episodes (such as extreme flood or drought) occur, fish and dependent wildlife cannot re-colonise the affected area, leading to localised loss or even extinctions.
Restoring fish access remains the most important and by far the most cost effective river management technique that can be undertaken on both river systems. For details of how we have been restoring fish access please see "Reconnecting the rivers".
The Severn Barrage
History
The idea of a Severn Barrage is nothing new. Early proposals in the mid 1800's were mainly driven by the need for harbours, flood defence and transport links across the estuary. From the 1920's onwards, however, initiatives were more born out of aspirations to harness the energy from the Severn's 14 metre (45 foot) tidal range, the second largest in the world. The Severn estuary is a habitat that is unique for its massive intertidal zones and huge volumetric flows of water. It is a vast overwintering site for a whole range of migrating birds but of particular relevance for the Foundation, it is the conduit for several extremely rare migratory fish species: allis and twaite shad; sea and river lamprey; Atlantic salmon, sea trout and European eel.
Against the background of climate change, the need to drastically reduce the use of fossil fuels that release stored carbon and a timely opportunity to renew or upgrade our outdated and under invested power generation systems, the government is investigating all potentially "renewable" sources of electricity generation. For full details please click here.
An inspection of the Severn estuary and its huge tidal range would suggest that there should be potential for harnessing the massive forces of water movement to generate renewable electricity, thus reducing our dependency on fossil fuels.
Drivers for the Barrage
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30% of UK's electricity generation will be lost by 2020.
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40% of our electricity needs to be from renewables (currently < 1% but targeted at 10% by 2020).
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Populist and big business pressure.
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Tidal power is a genuine renewable source.
In October 2007, the Sustainable Development Commission reviewed the UK's tidal energy possibilities, including the Severn estuary. Some of their conclusions were:
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A Severn Barrage should be part of a wider action on climate change.
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It must comply with existing environmental legislation i.e. Habitats Directive.
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Provision of compensatory habitat is an integral part of any proposal.
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Early work on scientific and legal feasibility of compliance and cost should be a priority.
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The Severn tidal range could generate 5% of UK electricity.
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The Severn tidal stream resource is not one of UK top ten sites.
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The project should be government owned and run.
Click here for the full report.
Next ...
A government feasibility study, started in 2007, concluded its first phase when a public consultation was launched on 26th January 2009. This public consultation was finished on 23rd April and covered, amongst other things, the proposed scope of the Strategic Environmental Assessment (SEA) for up to 11 possible barrage schemes. This was shortlisted to 5. Regrettably, environmental legislation was not considered at this stage.
A consortium led by the engineering consultants, Parsons Brinckerhoff (PB), has been appointed to manage the next stage of the project. However, in 2010 the (new) government decided not to proceed with any of the schemes. Privately funded consortia are not excluded from considering options.
| Proposal | Location | Installed Capacity | Construction Cost | CO2 Savings/year |
| Shoots Barrage | By Severn road crossings | 1.05 GW | £3.2bn | 1.2 Mt |
| Beachley Barrage | Just upstream of the Wye confluence | 0.625 GW | £2.3bn | 0.7 Mt |
| Fleming Lagoon | Between Newport & Severn Road crossings | 1.36 GW | £4.0bn | 1.0 Mt |
| Bridgwater Bay Lagoon | English shore between Hinkly Pt & Weston Super-Mare | 1.36 GW | £3.8bn | 1.1 Mt |
| Cardiff-Weston Barrage | (Lavernock Pt - Brean Down, known as Severn Barrage) | 8.64 GW | £20.9bn | 7.2 Mt |
So what are the Issues for us?
One would expect an environmental organisation set up to restore and protect fish and fisheries to be against any scheme that could severely reduce or extinguish runs of migratory fish. Salmon, shad and lamprey currently enjoy the protection of the EU Habitats Directive: this despite are concerns for the need to combat climate change.
The schemes shortlisted will present massive problems for planners attempting to reconcile these important environmental considerations. We believe that this crucial aspect should have been reflected in the short listing as the issue of providing compensatory habitat is such a "Significant Challenge" that the process may be set back very substantially while resolution is investigated. Equally, the barrage presents huge challenges to one of the most important RAMSAR sites, where birds both live and over-winter in the unique habitat. Colleagues in the RSPB, WWF, Wildfowl and Wetlands Trust (Slimbridge) and other wildlife trusts therefore have parallel concerns and together we are mounting a united opposition. The size and strength, experience and ability of these organisations make welcome allies.
There are, however, plenty of other reasons for opposing the barrage, amongst which are ...
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It's disproportionately expensive (see table below).
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Tidal Power is Intermittent: power produced at night and in short, heavy bursts requiring grid restructuring
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It won't solve the problem of either climate change or power generation as effectively as certain other schemes.
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There are as yet unresolved technical issues.
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There is a lot of money involved.
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It's a risky "all eggs in one basket" scheme.
Are there better alternatives to the Barrage?
The table above would suggest so. The list of potential alternative sources of energy includes ...
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Tidal stream – elsewhere in UK more suited.
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Wind power (sea and land).
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Nuclear.
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Micro generation – new technologies being developed.
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Energy conservation (turn off the lights!).
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Tidal reef
Further reading:
