Tom Pow alongside the Tauroa Stream, which has been cleared of willow and other blockages on his Mata farm. Photo / John Stone
Ruakaka River Liaison Committee ratepayer representative Tom Pow fears a weather "bomb" similar to Cyclone Bola in 1988 could cause catastrophic flooding on farms, roads and residential properties around the Ruakaka estuary.
"If the river and water courses upstream suddenly cleared their throats all the mud, dead trees, logs and debris in them could slide downstream causing major damage," he said yesterday.
The liaison committee was set up in 2014 as a subcommittee of the Northland Regional Council (NRC) to remove risk to communities through flooding and other natural events.
To this end, it is helping the council develop a river management plan to reduce the flood risk in the 89.6sq km Ruakaka catchment, 68 per cent of which is in pasture with 22 per cent in indigenous forest.
The committee is chaired by NRC elected representative Craig Brown with Juliane Chetham as an iwi representative, Mr Pow and Warren Daniel as ratepayer representatives, Peter Batten from the Ruakaka Residents and Ratepayers' Association, Georgina Newmann from the NZ Transport Agency and Lynnie Gibson from the Department of Conservation.
They are to meet in November to discuss whether a management plan should be introduced with a separate drainage district and targeted rating on the Ruakaka flood plain.
Mr Pow, like many farming alongside flood-prone rivers, considers the main function of a waterway is to carry heavy rain and flooding to the sea as quickly as possible.
But with wildlife sanctuaries, biodiversity and water quality now priorities, rivers are blocked by debris, water courses, silt and sandbanks change, shallow channels fill with stagnant water and invasive plants like mangroves move in.
"Let's stop the fluffy duck approach," Mr Pow said.
"We need to clear waterways of debris, return adequate flow rates and not plant anything which will cause blockages in the future."
Flooding had in the past closed State Highway 1 at Ruakaka and Mr Pow said access to the area should be as stormproof as possible so people there were not cut off from Whangarei medical and other services.
AgFirst Northland land and environmental management consultant Bob Cathcart agreed with Mr Pow that the flood risk at Ruakaka ruled out doing nothing as an option.
"Blockages in the Ruakaka River need to be tidied up," he said.
Mr Cathcart recalled how the Northland Catchment Commission planned in 1971 to clear willows from river channels.
The scheme had government support, but local funding was also required. The former Whangarei County Council didn't support it and no progress was made.
NRC environmental services group manager Bruce Howse said the council was looking at the costs and benefits of clearing the Ruakaka River between Flyger Rd and State Highway 15A, where the waterway is congested with willows in mid-channel.
"We're also looking at how the work could be funded."
The NRC was also examining the flow from five main subcatchments, seeing if their flow into the main channel could be staggered so all the water didn't get to the Ruakaka floodplain at once.
"That's still being analysed before we go back to the next liaison committee in November," Mr Howse said.
Given the final say, Mr Pow said the NRC would do good work if the community got behind it.
He believes the situation is salvageable, but it could take up to 20 years of firm management to bring the risks of Ruakaka estuary flooding firmly under control.