The Canterbury regional council says repairs to quake-damaged rivers will cost millions of dollars.
The council says preliminary estimates of the cost of repairs to the Waimakariri and Kaiapoi rivers after February's earthquake amount to $2 million.
Principal river engineer Ian Heslop says that's on top of an estimated $3 million worth of repairs being undertaken after last September's quake.
However, he says, repair work completed after the first quake has held up well and stopbank damage is only minor to moderate.
Mr Heslop says additional damage to the rivers was mainly limited to downstream of the northern motorway, and he hopes repairs will be finished by June.
Repair work to the Halswell River is also under way.