Environment agency representatives have raised concerns about the ecological impact of a Severn Barrage.
The Energy and Climate Change Select Committee held an evidence session in Westminister this morning to investigate proposals for an 11 mile tidal power station across the Severn Estuary, submitted by Hafren Power last December.
But representatives for the Environment Agency giving evidence raised concerns about the impact on flooding and also on fish species reliant on the Severn.
In their submission to the committee Haffren Power claimed the barrage will defend an estimated 50,000 hectares of land from flooding and protect 90,000 existing properties for at least 120 years.
But Ed Mitchell's, director of environment and business, said the Environment Agency already has a £1 billion plan in place for the next 100 years and the added benefits of the barrage were unclear.
“The barrage across the Severn has potentially big positive and negative impacts on flood defences. It might provide additional defence for instance against storm surges but it may prove difficult in terms of flood risk higher upstream than the barrage,” he said.
“In broad terms we think it is probably sort of cost neutral in terms of flood defences.”
The primary concern for the Environment Agency is the predicted constriction of the tidal range caused by the barrage.
Richard Creswell, Director for the South West of England, said: “If you constrain the tide from between 0m and 14m to 3m and 12m then the tidal action is acting on the coast line in a much narrower band, so we would therefore want to look to see if it would erode the defences quicker than it does now.”
The fate of local fish species was also a concern for the agency with five species potentially under threat including salmon, lamprey and the migratory shad, which has only four breeding grounds in the UK three of which could be upstream of the barrage.
With the turbines Haffren proposes to use in the barrage spinning at 9m/s at the tips, there are serious concerns about the danger of significant numbers of fish being killed as migratory species such as salmon can spend up to four months in the estuary.
Mike Evans, from Environment Agency Wales, said most studies to date have demonstrated high fish mortality rates of up to three per cent and to make the proposal feasible in the eyes of animal protection legislation the figure would have to be reduced to under one per cent.
“We are looking at a quantum shift in mortality rates,” he said. “It’s a very, very big challenge.”
But speaking before a previous evidence hearing in January Tony Pryor, Hafren Power’s chief executive, said he was confident of the plans.
He said: “We will deliver green, safe, secure and ultimately the cheapest electricity for Britain into the next century. The barrage will create 20,000 construction jobs and protect tens of thousands of properties from rising sea levels and storm surges.
“We believe this is a project whose time has come but it will not be at the expense of upstream port jobs, fish or birds. We are committed to working with everyone in the months and years ahead to show how new technology and planning can mitigate risks. We are determined to get it right.”