Moutoa Floodgates

The Moutoa Floodgates are a key part of Manawatū’s flood protection system. First commissioned in 1962, they’ve been helping to protect more than 280 km² of land in the lower reaches of the Manawatū River from flooding ever since.

With flood risks increasing and the region relying heavily on ageing infrastructure, upgrades to the Moutoa Floodgates became essential.

Originally built after the catastrophic 1941 floods, the nine-gate structure can divert up to 2,500 m³ of floodwater every second through a 10 km spillway to the Tasman Sea. It’s been the backbone of flood protection in the Manawatū for decades and is still recognised today as one of New Zealand’s most significant engineering achievements of the 20th century.

We were proud to have led the project, aimed at extending the life and reliability of the Moutoa Floodgates.

The scope for the project involved a series of mechanical and electrical upgrades with structural modifications to make sure the gates would continue to operate safely and effectively for years to come.

We led the scoping of key floodway elements needing upgrades to extend the asset’s life and improve how it operates - all while keeping the project timeline front of mind. Working closely with our client, we developed a programme of works that balanced both their priorities and the needs of the asset.

As Horizons Regional Council’s trusted partner on the project, we supported the engineering journey from concept through to reference design – identifying solutions that reduced on-site work and helped keep the project on track. We worked closely with the client to develop and review tender documents for the Design and Build Contractor, covering the delivery of nine new gate winch sets and modifications to the existing concrete piers.

Maintaining flood protection throughout the works was a top priority. Construction was carefully staged to minimise the number of gates offline at any one time, making sure the system remained ready to respond in an emergency.

In parallel with the physical works, we supported Horizons Regional Council with long-term operations and maintenance planning, helping to futureproof the asset and deliver long-term value for ratepayers.

As Owner’s Engineer, our role also included shaping the procurement strategy to meet critical funding deadlines and providing technical guidance through tender, fabrication, construction and commissioning.

The Moutoa Floodgate Upgrade Project has accomplished more than merely prolonging the lifespan of this iconic piece of infrastructure; it has celebrated a heritage of innovative engineering and delivered sustained flood resilience. The upgrades have improved the floodgates’ reliability, helping protect over 280 km² of pastoral, horticultural and urban land in the Foxton and Shannon townships, and the surrounding areas.

With extreme weather events becoming more frequent, these improvements mean greater peace of mind and long-term security for communities, farms and infrastructure across the Horowhenua District.