$4.6M for floodgate on Kaipara’s Raupo Drainage Scheme

Part of the Raupo Drainage Scheme in Ruawai, that is due to get a new $4.6 million floodgate. Photo / Tania Whyte

Around $4.6 million will be spent on a floodgate on Ruawai’s Raupo Drainage Scheme to help protect productive land from being inundated with saltwater.

A new floodgate planned for the Raupo drainage scheme can proceed after the Kaipara District Council agreed in its December meeting to redirect funding from the Te Kopuru stopbank project to build the floodgate.

Floodgate G, to the south of Ruawai, is one of two floodgates initially planned for as a way to protect a large area of land from being overrun with salt water.

Stopping the salt water at the entrance to the canal minimises the need to raise around 30km of stopbanks along both sides of the canals.

The council applied to the Ministry of Business, Innovation and Employment (MBIE) for $20 million to build two floodgates and raise 13km of stopbanks between Dargaville to Te Kopuru. Of the $6 million received, MBIE allocated $2.5 million for the floodgates and $3.5 million for the stopbanks.

By consolidating the funding the council can complete one floodgate and avoid the need to pay back the $700,000 already spent on floodgate design to MBIE. MBIE requires funding to be returned if councils are not able to complete projects described in their contracts.

A map showing the sites of two floodgates initially planned for the Raupo Drainage Scheme in Ruawai. Floodgate G will now be built after Kaipara District Council consolidated funding from its Te Kopuru stopbank project

Mayor Craig Jepson said building floodgate G was the best way to draw value from the funding the council has.

“We’ve focused funding where it will protect the largest land area and the most significant infrastructure. That includes State Highway 12, which provides a vital link from Dargaville across the district.”

Anin Nama, KDC General Manager Infrastructure Services, said none of the projects have been stopped and the council will be in a good position to continue the stopbank and floodgate projects when future funding becomes available.

“This decision allows us to progress an integral piece of infrastructure to protect some of Kaipara’s most productive farming area. Completing floodgate G also builds on the work we are already doing with the Ruawai/Raupo community through our Adaptive Pathway pilot programme, planning how to adapt to rising sea levels,” Nama said.

The total cost of the floodgate is expected to be around $4.6 million. The remaining $1.4 million is to be spent on raising about 2km of the stopbanks to a height of 3.5m.

The Raupo Drainage District covers around 8700ha of highly productive fertile land surrounding the small settlements of Te Kowhai, Nau Mai, Raupo and Ruawai. A network of 70km of stopbanks, 140km of canals and drains, 52 floodgates and one flood pump currently protect the area.

The floodgate structures will protect the council’s assets and the strategic SH12 from rising river levels. The exclusion of salt water from these canals also allows for strategic freshwater storage within the catchment area.