Historic Fenland waterways are not under threat from plans to create a massive new wetland reserve stretching from the outskirts of Cambridge almost to Ely, it was claimed last night.

Historic Fenland waterways are not under threat from plans to create a massive new wetland reserve stretching from the outskirts of Cambridge almost to Ely, it was claimed last night.

Anglers and conservationists feared the National Trust's Wicken Fen Vision could lead to water levels in the Cambridgeshire Lodes being lowered.

The proposal was among the options in a leaked consultant's report into how the Environment Agency could manage the waters in the future.

But yesterday Jon Megginson , the trust's project manager for the Wicken Fen Vision, said: “The National Trust is not advocating that maintenance of the Lodes be abandoned or that they be removed.”

He said plans to expand the Wicken Fen reserve did not depend on lowering the Lodes, whose future would be decided by the Environment Agency.

The national trust launched its vision to expand Wicken Fen to 16 times its current area, by buying up parcels of farmland and returning them to fen, in 1999.

But anger erupted after a scoping report on different options for managing the Lodes, commissioned by the EA, became public last month.

It listed five options, ranging from maintain the status quo to do nothing and allow the banks of the lodes, which are unstable in places, to collapse.

Consultation over the future of the waterways will be carried out later this year, before the agency decides which option it prefers.

Last night, an EA spokesman said: “A feasibility study is being undertaken to determine the best long term future for the Ely Lodes taking into account environmental, economic and technical considerations.

“The potential impact of the Wicken Fen project on these embankments is one of many things being taken into account. We hope to make a decision later this year.”

Privately, National Trust officials expect the agency to favour maintaining the status quo and preserving the Lodes. But Mr Megginson said if the EA recommended lowering their levels, the trust would oppose the move.

Nearly 1,000 people have signed an online petition on Prime Minister Gordon Brown's 10 Downing Street website, launched by retired county councillor Geoffrey Woollard.

Last night, Mr Woollard said: “My belief, which is shared by many others, is that the 'Wicken Vision' and the threat to The Cambridgeshire Lodes are issues that are inextricably intertwined.

“If the National Trust succeeds with its plan to buy 10,000 acres of land and partially flood it, the lode banks may be undermined from the outside.”

Dennis Moules, East Anglian liaison officer for the Pike Anglers Club, said: “I welcome the National Trust's views but why didn't they come clean to start with - we'll wait with anticipation to see what happens next.”