The cost of building a landmark visitor centre in the heart of Broads has doubled in less than a year.
The Broads Authority hopes that developing the attraction at Acle Bridge will boost tourism and get the public thinking about climate change.
But a report leaked to this newspaper reveals some serious challenges.
The centre would need to attract around 90,000 visitors a year to bring in enough money through parking charges and a cafe.
The site is also too small for the centre, meaning the Authority needs to buy neighbouring farmland.
The total project costs are also unknown, the Authority said.
When it launched a design competition for the centre last year the budget was £750,000, but several different sources have said the number is now twice that at £1.5m.
It is in discussion with the New Anglia Local Enterprise Partnership for some of that money.
Critics also point out the building would have to be constructed on a floodplain and the Authority would be asked to judge its own application.
Paul Rice, who is a member of the planning committee, said: 'I'm not sure it is the right location and I'm concerned about where the funding would come from.'
Lana Hempsall, who represents Broadland Council on the Authority, added: 'This building in its current form has never come in front of members for formal approval nor have members formally approved or voted on a budget but the chief executive is pressing ahead regardless.'
But chief executive John Packman said: 'Members are updated on progress at every meeting.
'The Authority will follow its normal practice in determining its own planning applications by using an external planning consultant.
'The building is designed to demonstrate sustainable development principles.
'The project is intended to encourage people to appreciate and care for our National Park and increase understanding of the potential impacts of climate change, sea level rise and the actions we can all take to mitigate the impact of these future challenges.'
He added the centre had been designed to be higher than the flood plain.
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