Damage from May's big flood in the lower Waitaki River could cost $446,700 to repair.
Work has already started.
Channel work is being done by a 50-tonne bulldozer.
It could take "months to complete", Environment Canterbury (Ecan) senior engineering officer Bruce Scarlett said yesterday.
The damage occurred when heavy rain in the upper catchment over-filled hydro storage lakes.
Meridian Energy Ltd was forced to release flows.
These hit a peak on May 17 of 1554cumecs, the highest since 1995.
After that, high flows continued as Meridian reduced its lake levels.
Mr Scarlett said that caused damage to some of the river protection groynes.
This included one which had been demolished.
It would cost about $90,000 to repair.
Further downstream, there were several places where the river had broken out of the fairway on to farm land.
Channel work would be needed to remove the water.
This would be followed by new protection work.
"The first phase, which we have started, is to try and ease the water pressure against the edges where it has broken out," Mr Scarlett said.
A bulldozer had been working for the past few weeks on the river at Station Peak.
It was now at the Kurow Creek area.
Most of the damage occurred during the May flood because of the duration of high flows.
A two-day flood of 900cumecs in January, and another which peaked at about 1400cumecs in April, only caused minor damage.
A meeting was held with the Lower Waitaki River rating liaison committee on June 24 to report on the damage, its cost, a programme of works and how it would be paid for.
The lower Waitaki rating account had very few reserves and would go into debt to pay for the work.
The cost would be recovered over the next few years.
Work on the river is paid for from the lower Waitaki river rating district.
Meridian pays 40% of the cost.
Property owners along the river who benefit from the work pay 20%.
The remaining 40% comes from rates over the whole region.
The Otago Regional Council also collects rates for river work, which is managed by Ecan.
