Teams of contractors are working to repair earthquake damage to stopbanks in the Waimakariri and Kaiapoi rivers in Canterbury.
About 25% of the length of the stopbanks have been damaged but engineers say the risk of flooding is low.
In some places the stopbanks have shifted sideways about five metres and subsided by 1.5 metres. There are also large cracks running through them.
Five teams of contractors with earth-moving equipment are filling the cracks and rebuilding the banks.
Repairs for the worst-affected areas are expected to be completed over the next few weeks.
The regional council says no significant rainfall or high river flows are predicted, and the risk of either river flooding is low.