Plans have been revealed for a tidal barrage stretching from Norfolk to Lincolnshire, which could generate tidal power, protect the Fens from flooding and allow a new deep sea container port to be created.

But conservation groups fear the proposals would have "catastrophic impacts" on nature and wildlife.

Centre Port, which is behind the scheme, wants to build a hydro-electric dam across The Wash from near Hunstanton on the Norfolk side of the estuary to near Skegness in Lincolnshire.

It says the £2bn barrage would create the world's first tidal-powered container terminal and help protect the low-lying coastline and inland communities from rising sea levels and increasingly-frequent storm surges.

Eastern Daily Press: Centre Port claims the barrage would protect The Wash and its habitatsCentre Port claims the barrage would protect The Wash and its habitats (Image: Matthew Usher)

It adds without the scheme many people, communities, businesses, road, rail and water infrastructures are at risk from permanent flooding."

The firm's chief executive James Sutcliffe said: "We can control storm surges so all the bird sanctuaries, salt marshes and so on don't get washed away, it's going to conserve The Wash and its bird life like it is today."

Mr Sutcliffe said the tide would be allowed to enter and leave the estuary via the turbines, which would generate enough electricity to power 600,000 homes, along with the port, which could handle 1.5m containers a year.

Eastern Daily Press: A map showing the route of the proposed barrageA map showing the route of the proposed barrage (Image: Centre Port)

He said the port would be closer to key markets in the East and West Midlands than Felixstowe for container lorries and could have a ferry link to Ostend to cut lorry journeys.

But the RSPB, Norfolk Wildlife Trust (NWT), Lincolnshire Wildlife Trust (LWT), the Wildfowl and Wetlands Trust (WWT) and Wild Ken Hill Estate are urging developers to rethink the plan.

In a statement, the groups say: "The Wash is the UK’s most important estuary for wild birds, home to England’s largest common seal colony, and an important fishery.

Eastern Daily Press: Conservationists say The Wash is the UK's most important estuary for wild birdsConservationists say The Wash is the UK's most important estuary for wild birds (Image: Matthew Usher)

"A tidal barrage would fundamentally alter the nature of the intertidal habitats on which this wildlife depends. 

"Construction of a barrier across the mouth of The Wash would displace the flow of tidal water in and out of the estuary, raising concerns this could lead to greater - and more frequent – flooding, and cause significant coastal erosion."

Dominic Buscall, project manager at Wild Ken Hill at Snettisham, said:  “The idea for a Wash Barrier is a non-starter. We absolutely cannot afford to interfere with this unique and incredibly special ecosystem, especially in light of the government's commitment to stabilise the decline of biodiversity by 2030.  

Eastern Daily Press: Dominc Buscall, project manager at Wild Ken HillDominc Buscall, project manager at Wild Ken Hill (Image: Chris Bishop)

“A Wash Barrier is also likely to be deeply, deeply unpopular with residents around The Wash.

"We derive a huge variety of benefits and pleasures from living on the seaside, and do not want to live next to an artificial saltwater pond, nor the significant amount of new infrastructure required to service it.” 

Eliot Lyne, chief executive of the Norfolk Wildlife Trust, said: "With its vast exposed mudflats and warm, shallow waters full of invertebrates,  The Wash is one of the UK's most important estuaries for wild birds and supports internationally important bird populations including redshank and knot. 

“To ensure we play our part in tackling the global biodiversity crisis, it is our responsibility to safeguard this incredible landscape."  

Eastern Daily Press: Eliot Lyne chief executive of the Norfolk Wildlife TrustEliot Lyne chief executive of the Norfolk Wildlife Trust (Image: Danielle Booden)

Nick Bruce-White, the RSPB's director, said: "Spending millions of pounds on assessments and surveys is a waste of time and money that could be better spent on more workable, established solutions to generate green energy, such as wind and solar power.

"A similar development along the River Severn was dismissed by a House of Commons Select Committee in 2013 as 'prohibitively expensive'. The development was later cancelled on economic grounds."

But Centre Port's prospectus says: "The project provides a major flood defence for the whole of The Wash area, extending to Peterborough and Cambridge.

Eastern Daily Press: Centre Port claims its proposals would safeguard The WashCentre Port claims its proposals would safeguard The Wash (Image: Matthew Usher)

"It preserves The Wash's natural areas for wildlife, which will otherwise be lost through climate change in two generations."

It says the barrage would provide green energy from turbines powered by the tides, adding: "Unlike wind and solar, it is consistent and predictable energy from the Hydroelectric dam in the sea defence as tides are predictable for hundreds of years."

It says the structure would connect Norfolk with Lincolnshire and help regenerate King's Lynn, Boston and Wisbech, along with creating a new west-facing beach.

Power company Centrica has signed an expression of interest in electricity from the scheme.

Plans for a barrier were proposed in 2008 but abandoned after an outcry from conservation groups.

But in 2019, the Environment Agency said some kind of barrier might one day be needed to protect low-lying areas of King's Lynn

Centre Port is now trying to raise £5m for a feasibility study.