Tasman weather - Riwaka, Motueka Photo: RNZ/Mark Papalii
A government report has found local councils need to be doing more to prepare for flooding and to mitigate the risks it poses to communities.
In a report tabled in parliament today, the Auditor-General found flood risk was not consistently understood nationwide.
It looked at how two councils, Tasman District Council and Waikato Regional Council, mitigate flood risks from rivers and other waterways and found both need to carry out more work to make better-informed decisions about intended levels of service for mitigating those risks.
Auditor-General Grant Taylor said appropriate planning, investment, and monitoring could reduce the impact of flooding.
"Communities need confidence that council flood defences are in the right places, built to the right standards, and properly maintained."
The report made four recommendations, that the Tasman District Council prepare a framework to prioritise the maintenance and capital work needed for its flood protection infrastructure and prioritise improvements to its asset management processes.
It also recommended that both councils improve their understanding of flood risk, including by assessing the full impact of potential flooding for a range of flooding scenarios and improve their engagement with the public to ensure that their communities understand flood risk and the extent of flood protection in their regions.
The report said flooding was New Zealand's most frequent natural hazard and its impact could be significant, disrupting critical services like roads and hospitals and energy and wastewater infrastructure.
It also caused disruption to livelihoods and in worst cases, loss of life.
Tasman weather - Riwaka, Motueka Photo: RNZ/Mark Papalii
The report said the recommendations in the report were relevant to all councils that were responsible for flood protection infrastructure, in order to mitigate flood risks effectively.
Report comes of the back of Tasman's worst flooding in decades
The Tasman District experienced back to back storms in June and July, described as the worst in 150 years, that caused damage to farms and rural properties, with land lost to swollen rivers, crops inundated with silt and fences washed away.
More than 60 roads were closed due to flooding, landslips and fallen trees and hundreds of homes were assessed for damage with a small number deemed unliveable.
The repair bill after the floods is estimated at $48 million, with around three quarters of that covered by insurance payouts or government contributions, leaving just over $11m in costs to the council.
Of the total costs, an estimated $20m will be spent on the river network.
Office of the Auditor-General manager of performance audits Evaan Aramakutu said one of the weaknesses identified in Tasman was the council's understanding of the condition of its flood protection infrastructure and the lack of a regular schedule of inspections.
"Waikato had a pretty systematic approach to inspecting all of their assets and updating their asset information around the condition. If they got a bit of wear and tear, would that affect their performance? Tasman didn't have that, or not to the same extent as Waikato, so they tended to rely on the age of their assets or observations they've made when they're out in the field to make decisions about renewals or maintenance work."
Tasman weather - Riwaka, Motueka Photo: RNZ/Mark Papalii
Aramakutu said both councils had a good understanding of where flooding was likely to occur in their regions, but more work was needed to quantify the damage and the potential costs associated with it, to inform the spend on providing protection.
He said there would always be a trade off between the cost of flood protection and the risks it protected against, so councils needed good understanding of the community's priorities and individuals needed clear information about what was protected and what wasn't, so they could be prepared.
The Office of the Auditor-General would check back in with both councils around a year after tabling the report, to see what progress had been made on its recommendations.
Recommendations welcomed by councils
Both Tasman District and Waikato Regional councils welcomed the reports findings.
Tasman District Council said since the audit began last October and following the flooding in June and July of this year, it had begun a comprehensive overhaul of its asset information on data and information collection/management processes.
Flooding was the most common natural hazard the district had to deal with.
Tasman weather - Riwaka, Motueka Photo: RNZ/Mark Papalii
"While our current intended levels of service for our flood protection infrastructure are largely based on the design standard that the stopbanks were initially built to, we remain focused on ensuring long - term resilience and protection for our river and floodplains to continue benefiting those who live and rely on them."
The council had taken steps to further inform the community, including release of a natural hazards map viewer and updated natural hazards information about flooding on its website.
It undertook community engagement on a natural hazards issues and options report earlier in the year to seek community views to inform work on the review of the Tasman Resource Management Plan's natural hazards provisions.
Since 2024, it had reinstated annual community Rivercare meetings across the district to discuss river management activities, including flood protection. The most recent meetings were held in mid-November.
"At the core of our future objectives is a safe and resilient river network, delivered sustainably and in close collaboration with landowners."
Waikato Regional Council chair Warren Maher said it had already progressed projects that addressed several of the report's recommendations.
"We could do more," he said. "The question is how much more can be done at a time when the central government has imposed rates capping, affordability is an issue for our communities, and significant changes are proposed to the structure of regional government."
The council's flood protection and land drainage assets include floodgates, pump stations, spillways and channels, as well as 620 kilometres of stopbanks, most of which are in the Waihou-Piako and Lower Waikato, some of which were developed in the 1960s. They are all supported by a network of automated rain gauges and river level/flow recorders.
The council estimates it will cost $2.9 billion over the next 50 years to operate, maintain and renew its flood infrastructure.
Maher said the report should give communities comfort the council was doing a good job when it comes to the management of flood protection assets, while at the same time providing direction for the ongoing understanding of flood risk.
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