The Environment Agency, together with its partners Witham First Internal Drainage Board, has completed works on the Witham Brook scheme in Grantham.
Summer storms in 2015 saw four properties and the Witham Brook Park Industrial Estate flooded when water levels in the brook rose substantially following heavy rain.
The culvert under the industrial estate became blocked by debris and rubbish, causing the water to back up and spill over its banks.
But now the EA has worked with partners to reduce the risk of this happening again.
The narrow, steep banks have been reshaped to make the channel wider, allowing it to better cope with heavy rain and sudden changes in water level.
The brook has also been connected to the nearby floodplain so extra water will spill into it first and be less likely to affect properties.