Climate change-related flooding could force 24 property owners to spend around $2.6 million raising the floor levels on their houses, with this bill potentially the tip of the iceberg for coastal homeowners around Northland.

Yesterday, Whangarei District Council (WDC) was meeting property owners at Waipu Cove, telling them water levels would creep closer and closer to their floorboards in the coming decades.

WDC's waste and drainage manager Andrew Carvell said that, while council could not force landowners to take action, it was time to discuss options. The $2.6 million figure comes from a report council commissioned into the issue.

"It may be a matter of people continuing to live there and the floods reaching a frequency where they decide it is unmanageable. But we have obligations under the Local Government Act to inform people of what we know," Mr Carvell said.


"Waipu Cove is particularly sensitive, but ... there's going to be similar situations along the coast."

Flooding in the area south of a tidal inlet at Waipu Cove was caused by low-lying land, the effect of high tides on the stormwater network, and changes made to the water course over the years.

A flood management report prepared for the council by Opus Consultants said doing nothing would see flooding increase, reaching a severity where 15 houses' floors were covered in water once every 18 months when heavy rain combined with king tides. Another nine would flood at less frequent intervals.

The report predicted this would happen once sea levels rose 0.5m. The most recent research from the Intergovernmental Panel on Climate Change showed a possible sea-level rise of 0.9m by 2090.

A man who owned a house identified in the report as needing to be another 80cm higher said it was clear WDC wanted homeowners to pay to solve the problem.

"As far as I'm concerned, I don't think it should be on a group of owners to foot the bill for what is a council drainage problem," he said.

Michael Haaken was a tenant in another low-lying house and said that, while he had not experienced a flood in the five months he had lived there, he had lived in other houses in the vicinity that were flood-prone.

The Opus report said the floor levels of 24 homes needed to be raised by amounts varying from 3cm to 1.1m to comply with WDC's current environmental engineering standards, with an estimated bill of $2.6 million all-up.

Mr Carvell said that, while there was no reason to panic, the "now effect" was that the flooding problem would go on property files.

"There will also be questions around insurance as that area continues to flood," he said.

The report also considered a piped discharge into Waipu Stream or the building of a pumped stopbank.

Mr Carvell said WDC had not discounted these and would be taking feedback from the community. He said if residents wanted a monetary contribution from the council, the best approach would be to make a submission on the 2018-2028 long-term plan.

Waipu Volunteer Fire Brigade chief fire officer Trevor Vaile said crews were called to floods at the Waipu properties in question about once a year: "There's nothing we can do. There's just millions of litres of water and if the tide's in there's nowhere for the water to go."