Northland Regional Council expects the biggest construction project it has ever undertaken - a $15 million flood scheme upgrade that will massively boost flood protection in and around Kaitāia - to be under way within two years, and completed in 2027.

The new seven-year Awanui scheme project is one of the crucial projects included in the council's new long-term plan 2018-2028, which is due to be formally adopted on June 21.

Te Hiku councillor Mike Finlayson said the scheme was designed to protect urban Kaitāia in a "once in a century" flood and a 1:20-year event in surrounding rural areas, and would be a game changer for the town.

Flood risks would be mitigated via a combination of improvements to stabilise stopbanks, flow diversion and works to mitigate the effect of the large, slow-moving Bell's Hill slip falling into the Awanui River.

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"Without the protection this scheme should give us, a flood of that 1:100-year magnitude in urban Kaitāia could cause tens of millions of dollars in damage and potentially put lives at risk," Finlayson said.

The value of the work would outstrip the $11 million-plus spent on the Hopua te Nihotetea detention dam, which officially opened two years ago and was designed to better protect Whangārei's CBD from floods.

Thirty per cent of the capital works in Kaitāia would be paid for by a 60 per cent increase in the existing targeted rate, which would raise an extra $442,000 annually, with the remaining 70 per cent to be funded by ratepayers regionwide via a new regional flood infrastructure rate.

Finlayson said there had been strong support for the scheme at a local level, but Far North residents had been concerned about the burden it would place on local ratepayers.

"Council listened to those concerns, which is why we moved away from a 50/50 funding split between those affected by floods and all ratepayers in the region, as originally proposed in the LTP, to the 70/30 split, with all ratepayers covering the larger share.

"For little more than $2 extra per ratepayer across the region, schemes like this became much more affordable at a local level for communities protected by existing and ageing flood infrastructure work. The split also reflects the wider regional benefits from having Northland's main service hubs better-protected from flooding."

He said region-wide, the millions of dollars of major new flood works planned under the new LTP would be repaid over 60 years, spreading costs more equitably across multiple generations that would benefit, and making them more affordable for smaller communities.

The LTP was the beginning of a long-running interaction with locals over the Kaitāia project.

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Finlayson acknowledged the Awanui River Flood Management Working Group, whose members, past and present, had given their time over many years to work on the scheme for the benefit of the wider Kaitāia community.

Councillors had also listened to feedback on flooding at Panguru, agreeing to bring forward by five years about $440,000 of planned flood scheme work. Project design and consent work, originally to begin in 2023, would now be done this year, with construction - stopbanks and widening a stream channel - to begin next year.