It's crunch time for homeowners in Whanganui's flood-prone Anzac Parade.

After decades of trying to hold back the tide of serious flooding, Horizons Regional Council has embraced the managed retreat option.

And that means owners will have the option of selling their home, having it raised or having it moved to higher ground, if Horizons' plans are approved.

The proposal is part of the regional council's 2018-28 long-term plan and it includes starting a managed retreat fund of $50,000 in the first year. That has seen Horizons projected rates increase soar to 7.44 per cent.


However, at a public meeting last week, regional councillor Nicola Patrick warned that people had already said $50,000 would not go far.

Horizons' river manager Ramon Strong said the money would build up over the years, and people would be able to sell, move or raise their houses if they wanted.

"It won't be a red zone situation," he said. "We're not telling people they have to go — it will be a voluntary arrangement."

Some at the meeting asked whether the council would pay market rates for the houses and whether the proposal would reduce the value of their properties. Despite the history of flooding, houses in the flood zone are still being bought and sold.

Horizons says that whatever proposal is adopted, it has to be the same across the region, with other flood-prone houses in Whangaehu and Feilding to be considered.

In view of the managed retreat preference, Horizons is not proposing to raise the Anzac Parade stopbanks which were overtopped in the June 2015 flood.

However, the council is proposing to put a "relief gate" in the stopbanks to let water out more quickly, and has spent $320,000 clearing vegetation out of Matarawa Stream to allow it to flow faster.

It also proposes diverting all, rather than most, of the Matarawa's water into the Mateongaonga during floods. Whanganui District Council could stop the stream backing up by increasing the size of the Gerse Street culvert and the pipes under State Highway 4, Mr Strong said.


Horizons proposes to rate property owners right across Whanganui for clearing the stream. It will cost ratepayers 74 cents a year per $100,000 of their property's value.

Some people at the meeting wanted the river dredged. But despite extra sediment in places, the Whanganui had the same carrying capacity it had in June 2015, the meeting was told.

Horizons also proposes to erect stopbanks to protect Putiki, provided the Ngatarua Stream can be accommodated. These stopbanks would cost $1.2 million and be started in six years' time, and Mr Strong said Putiki people were "quite keen" to have them.

A flooded Victoria Ave, June 21, 2015. Photo/ file
A flooded Victoria Ave, June 21, 2015. Photo/ file

No stopbanks are proposed for Taupo Quay, despite riverside buildings being flood-prone. That area will be kept open because people like to use it.

Down river at Balgownie, Horizons proposes to close off a large gap in the stopbanks if Q-West boat builders moves and no longer needs river access.

Another lower river matter is the deteriorating state of the north and south moles and other river training structures. Fixing them will cost $4.9 million over 30 years.


Alignment work there has been added to Horizons' responsibilities. For the 10 years to 2028, the Whanganui council is to pay 25 per cent of the cost of work done downstream of Landguard Bluff, and Horizons the rest.

The most important structure to fix is the south mole, and the councils will seek central government funding for those repairs.

Horizons long-term plan is open for submissions and the council is keen to get the public's feedback.