Update No. 11

Marlborough’s stop bank network held up very well during the heavy persistent rain of recent days.

Council’s Rivers and Drainage Engineering Manager Andy White said the 220km network of stop banks proved resilient during the rain and significant flooding.

“Council’s ongoing investment including planning for contingencies at Spring Creek and major works at the Taylor Dam have played a significant role in the success of the system during this rain event,” he said.

The only new issue was at the confluence of the Waihopai and Wairau rivers where a section of the bank suffered damage, which was picked up during routine flood monitoring yesterday and resulted in part of Renwick being evacuated as a precautionary measure.

“An immediate temporary fix was made when we saw early signs of failure and it was monitored closely throughout,” Mr White said. “There will be a fast-tracked solution to repair the damage.”

The Spring Creek stop bank performed well despite engineers’ concerns when drilling showed it was compromised in 2022/23.

“It was extensively monitored during this event and the good news is there was no observation of any seepage or slumping – the bank performed better than we had hoped,” Mr White said. “We have every confidence the community is safe and they were only evacuated as a precaution.”

The stop bank is due to be rebuilt by June 2027.

Rivers in the region remain high, particularly the Taylor/Opaoa and Wairau but are being constantly monitored, and aerial inspections are due to take place today.

A full damage assessment of the network will take place next week with key agencies.

Meanwhile Operations and Maintenance Engineer Stephen Rooney is asking Blenheim residents to use toilets with caution.

“The sewer system is still running at 1.2m above normal and will be a while before it is back to normal,” he said.

Residents are asked to only flush toilets when necessary and use water sparingly.

Rai Falls received 381mm of rain, Onamalutu at Bartletts Creek Saddle 260mm and central Blenheim 109mm, in line with initial MetService New Zealand forecasts.

There continues to be widespread surface flooding throughout the region. Travel is still not recommended unless absolutely necessary. If travel is required, please drive with extreme caution and to the road conditions.

Sign up to Antenno here: https://www.marlborough.govt.nz/services/apps/antenno

Keep an eye on MetService for watch and warning updates at www.metservice.com/warnings/home

You can track Council’s Floodwatch here: http://hydro.marlborough.govt.nz/floodwatch

Read the latest NZ Transport Agency update at: www.journeys.nzta.govt.nz/traffic-bulletins/wet-and-windy-weather-on-the-way-for-top-of-the-south-drivers

For further information on emergency preparedness go to: https://getready.govt.nz/emergency/floods

Image: The Waihopai and Wairau River confluence near Renwick, showing the compromised stop bank

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