Environment bosses are urging people to work together on flood defence plans.
The call comes ahead of the first public meeting on the controversial plans, which aim to tackle repeat flooding in the Ouse valley.
The Environment Agency said it wanted to put as much protection as possible in place following the autumn 2000 floods.
The proposals involve raising the river walls through the centre of Lewes and using the farmland south of the A27 to absorb flood water.
But the agency admitted the proposals would do little to help Uckfield, the other town in the Ouse catchment area badly hit two years ago.
Pressure group Lewes Flood Action said some parts of the historic town centre would have no extra protection leaving some homes and businesses unable to get insurance.
The group said the plans were inadequate and inconsistent.
Peter Midgley, area manager for the agency said: "I welcome the involvement of the people of Lewes and the Ouse valley. It is important we work together on this."
The public meeting will be at Lewes Town Hall on September 11 at 6.30pm.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article