Innovative floodgate boosts flood protection for Ruawai

An innovative new floodgate has been officially opened at G Canal in Ruawai, marking a major milestone for flood protection and resilience in the Raupō Drainage Scheme area and protecting key assets including State Highway 12 from tidal intrusion.

The $5.3 million project was delivered by Kaipara District Council and funded through central and local government, with $4.554 million contributed in 2021 from the COVID19 Response and Recovery Fund and $746,000 from council funding drawn from general rates.

G Canal is part of the Raupō Drainage Scheme, which protects around 8,700 hectares of highly productive land surrounding Te Kowhai, Nau Mai, Raupō and Ruawai, much of it at or near sea level. The scheme is supported by an extensive network of stopbanks, canals, drains and floodgates, with G Canal forming a key part of the system.

Kaipara District Mayor, Jonathan Larsen said the project was a standout example of what can be achieved through strong partnerships and technical innovation.

“Ruawai is one of Northland’s most productive food producing areas, and this floodgate plays a critical role in protecting the land that so many livelihoods depend on,” Mayor Larsen said.

“This project was made possible through collaboration between central government, council, the Raupō Drainage Committee, local landowners and community, engineers and contractors.”

The opening was attended by Regional Development Minister, Shane Jones, whose support was instrumental in securing the central government funding, the Mayor said.

“Minister Jones has been a champion for Kaipara for many years. I am deeply grateful for his assistance with this project and numerous others across the district,” he said.

Construction began in October 2024 and was completed in September 2025. The project involved significant technical and logistical challenges, including the installation of a cofferdam with 12 metre sheet piles, draining part of the river channel, and crews and machinery working below water level. Barfoote Construction was the contractor for the project, with GWE as design engineer and Crompton Engineering providing specialist engineering services.

Chair of the Raupō Drainage Committee, Ian Beattie said he is proud to see the completed floodgate in action.

“What looks like a simple structure is actually a project without peer in New Zealand. It has never been done before on this scale in a working environment so challenging – it has pushed innovation in both design and construction and is a credit to all involved,” Mr Beattie said.

The completed floodgate is to be operated and maintained by the Raupō Drainage Committee. Council says the system is already performing better than expected, improving drainage, preventing flooding and delivering efficiencies and maintenance savings across a wider area.

The committee will host an on-site open day for the community to check out the floodgate and learn more about how it works on Thursday 14 May (9am-12pm).