A proposed $5 million spillway could reduce the floods that regularly wreak havoc in the Mid North towns of Ōtiria and Moerewa.
The most recent deluge, in July 2020, swamped homes with contaminated floodwater, forced families to evacuate and left travellers stranded.
It came on the back of similar floods in 2014 and 2011, with smaller events between.
Now the Northland Regional Council, using a combination of ratepayer and central government funding, is proposing building a spillway to divert floodwaters from the Waiharakeke and Otiria streams away from homes.
While the exact route has yet to be decided, the idea is to skim water off the floodplain upstream of Pokapu Rd, then return the water to the Waiharakeke Stream at a point further downstream where its channel can handle the volume.
At present floodwater continues to flow along the floodplain, swamping Ōtiria and Moerewa on its way to the sea.
Regional council deputy chair Justin Blaikie said central government had agreed to stump up $2.89m, more than half the cost of the project, through the Provincial Development Unit.
The rest of the cost would be split with $1.5m from a Northland-wide flood infrastructure rate and $630,000 from a new targeted Taumārere rivers management rate.
Normally local residents would have to pay 30 per cent of the cost of flood protection but in this case, thanks to Government funding, the locals' share was about 13 per cent.
Blaikie said the council was currently gauging community support for the spillway, and the costs, via the Long Term Plan consultation process.
If the proposal goes ahead in its current form it would add about $1.45 a year to the Northland-wide flood infrastructure rate, and an extra $57.50 a year for 12 years for ratepayers in the targeted rate area.
Blaikie said local knowledge had been key to the project with residents Mike Butler, Wiremu Keretene and Murray Armstrong working with council staff and engineers to come up with potential spillway routes to reduce future flooding.
Meanwhile, the regional council is proposing a separate project to reduce flooding along Old Whangae Rd in Kawakawa.
That would involve building a 450m-long stopbank to deflect floodwater away from businesses. If approved work would start in 2024 and cost about $1.5m.
That would mean an extra $1 a year on the Northland-wide flood infrastructure rate and $29.40 annually on the local targeted rate starting in 2024.
If both projects go ahead the targeted rate in the Taumārere rivers catchment area would start at $57.50 and go up to $86.90 in 2024.
Fix under way for notorious flooding chokepoint
Work is under way to reduce flooding at a notorious chokepoint on Northland's state highway network.
The first major road to flood when heavy rain hits the Mid North is usually State Highway 1 at the bottom of Turntable Hill, Moerewa.
If the standard detour via SH11 also floods at Taumārere that leaves the Far North all but cut off from the rest of New Zealand, with SH15 or up the west coast on SH12 the only remaining routes — if they aren't closed as well.
Work to relieve the Turntable Hill flooding bottleneck started in January and is due to be completed later this month.
The $850,000 project is entirely funded by Waka Kotahi NZ Transport Agency, which is responsible for the nation's state highways.
The work involves benching a floodway just downstream of the bridge, where the streambed narrows from almost 20m wide below the bridge to a 5m channel.
The work will leave the stream as it is during low flow but in times of flood, the water will have somewhere to go.
It is designed to reduce flooding at the bridge to a one-in-10-year event.