A proposal for a tidal barrier on the Avon-Heathcote estuary has been rejected by a full meeting of the Christchurch City Council.
The council has been in the early stages of exploring a barrier to reduce the flood risk in low-lying parts of south-east of the city.
Parts of Christchurch dropped during the earthquakes and the areas are now more vulnerable to flooding.
A study found a tidal barrier was technically possible, but would cost up to $350 million to build, have a major impact on the estuary and would not remove the need for additional defences against flooding.
The council is continuing to work on other ways to prevent flooding.