West Coast council defends its flood plan after critics say it doesn't go far enough

Wednesday, 1 September 2021

At the mercy of alpine rain, will the Buller River deliver a large flooding event to the West Coast town of Westport? (First published May 22, 2020)

The West Coast Regional Council has defended its plans for flood protection in Westport, with its chairman saying it's time for action “not hand-wringing”.

It has presented two options for the town, which was inundated with floods on July 17 and 18 that forced more than 2000 of its 4500-odd residents to evacuate and left more than 460 homes damaged.

The Buller District Council criticised the two options for floodwalls and stopbanks along the Buller and Orowaiti rivers, saying the regional council did not take climate change or liquefaction into account and one of the options was no better than doing nothing.

It asked the council to do further investigation and consultation to include options such as managed retreat and raising foundations on existing and new buildings. It also said the cost estimates of $3.4m and $10.2m were likely too low for what was proposed.

* West Coast flood: Westport ratepayers baulked at $10m protection scheme in 2017

* Westport needs flood protection scheme, regional council chair says

Options put forward by the West Coast Regional Council for flood protection in Westport.

Regional council chairman Allan Birchfield and acting chief executive Heather Mabin issued a letter refuting some statements in the distrcit council’s submission on the flood protection plan.

They said the district council proposed spending more ratepayer funds on further investigations and managed retreat. They defended the options put forward, saying they were developed by both councils and a working group that included community members.

Birchfield and Mabin said the working group made the deliberate decision to design the floodwalls and stopbanks to the current climate scenario rather than a future scenario because affordability for ratepayers was key.

For example, the district council wanted flood protection that could cope with 1200 cubic metres of water, but the regional council’s proposal would be able to handle only 9500cums.

The stopbanks would be designed so they could be raised in the future if needed, the pair said.

Westport was flooded in July when the Orowaiti River overflow burst its banks.

Birchfield said the council had complete trust in the expertise and modelling used to design the protection works, which were reviewed and signed off as fit for purpose by water environment experts DHI Ltd.

“Now it’s time for the community to decide what action they want taken on their behalf.

“This is time for action, not hand-wringing and engaging more and more experts.”

He said both options significantly reduced the threat to life from the Buller River breaking its banks, and considering the protection of property and affordability for the community.

It was not possible to identify final costs until the work was tendered, but that was in line with how the regional council delivered other flood protection projects across the region.

“Westport and Reefton are currently the only major population areas on the West Coast that do not have any form of river, drainage or erosion protection scheme,” he said.

“This matter has been bounced around for at least two decades. We have now seen a significant flood event happen, and we do not believe the damage that occurred would have, had protection been put in place.”

Submissions close September 8.