Surfers vs the Severn dam

Surfers come from all over the world to conquer the Severn Bore - a unique wave that powers up the river for miles, creating one of the longest rides for watersports enthusiasts. But now they are furious over plans for a 10-mile "eco-friendly" hydro-electric barrage that will kill the wave for ever.

The surf on the River Severn, which is also home to porpoises, otters, rare fish and an astonishing array of bird life, is under threat after senior government sources signalled that ministers were backing the proposals, which would dramatically reduce the tidal flow of the river. The Government wants to harness the water power generated by 14m tides to supply up to 7 per cent of the UK's electricity demands.

But Steve King, who broke the world record for the longest continuous surf ride on the river earlier this month, reacted with dismay to the news. "The tide is the life blood of the river," he said. "I'm all for alternative energy - but what is the price we're going to pay? The environment here is unique. We are obliged to preserve it."

Peter Hain, the Secretary of State for Wales, told The Independent on Sunday that the barrage should be a priority in the Government's energy review. "This is one of the few renewable schemes that rivals nuclear in terms of the amount of electricity it can generate - but without the associated problems of radioactive waste and security risks," he said.

He said it could help to fill the looming "energy gap" which will emerge as nuclear power stations are gradually decommissioned. "This not just a climate change issue. This debate is about security of supply. It's about keeping the lights on," he added.

The Severn estuary is a harsh landscape of vast mudflats scoured by racing tides, but its unique ecosystem provides ideal conditions for large numbers of migratory birds. Otters, porpoises and rare fish are found in the river, while every winter, hundreds of thousands of waterfowl flock to the area.

The Severn barrage would be the largest project of its kind in the world by far. It would trap water at high tide, which would then be released through hundreds of turbines. The barrage would be fitted with locks to allow shipping upriver, but it would block migratory routes for fish such as salmon and eels, and would substantially reduce the estuary's tidal range.

If the scheme goes ahead, it will irreversibly change the estuarine environment, said Julian Branscombe, the chief executive of Gwent Wildlife Trust. "The barrage would turn the estuary into a vast lake with a slight tidal range. A site of international environmental importance would not just be damaged but destroyed," he said. "Porpoises will no longer visit, and should any of them be trapped inside the estuary when it is closed, they will eventually die out within the impounded waters."

Morgan Parry, the head of WWF Wales, said: "If we're promoting renewable energy in order to protect our environment it would be rather ironic to end up destroying one of the natural wonders of the United Kingdom."