Preliminary funding has been secured for a tidal surge barrier across the River Orwell.
The Environment Agency has given the go-ahead for the first phase of funding for the scheme which forms the central plank of the Ipswich Defence Management Strategy.
The £40M-plus solution was put forward by partners behind the Ipswich Flood Defence Management Strategy, including Ipswich Borough Council.
Work is expected to start in February next year on the first phase of the scheme which will see river banks being raised near Bath Street and near the Wet Dock entrance.
The barrier will be constructed across the New Cut, opposite the Island site, once further funding has been secured and is expected to be in operation early in 2012.
It means the Environment Agency will be able to safeguard the town from a one in 300 chance of flooding in any one year due to a tidal surge. Currently, the town is safe only against a tidal surge between one in 20 and one in 100 chance of flooding in any one year.
The project is one of the largest currently being implemented by the Environment Agency with the barrier alone forecast to cost £30M.
Project manager Nicolas Rowlinson said: "Following the allocation of funds we now enter a challenging and exciting few years as we work on the flood defence improvements identified in the Ipswich Flood Defence Management Strategy. Central to these improvements is the tidal surge barrier in the New Cut," he said.
"The tidal surge barrier will be in the lower part of the Orwell in the New Cut, probably in its mouth. The exact position will be determined in the coming months and the barrier will be tied into high ground with new flood defences. Everything upstream of the barrier will be protected against a flood from a surge tide which is the principal flood risk for the town," added Rowlinson.