Spillway opening marks completion of major capital works for the Rangitāiki River

A key piece of Eastern Bay of Plenty flood protection infrastructure has been officially opened, showing how innovation, collaboration and technology can come together for the benefit of the community.

On Saturday, 10 May, Toi Moana Bay of Plenty Regional Council, Ngāti Awa representatives and Associate Regional Development Minister, Hon. Mark Patterson gathered with local community members to officially open the Rangitāiki Floodway and Spillway.

The event marked the completion of the $50m project, which has been engineered to take pressure off the flood prone Rangitāiki River by diverting some of its flow into the floodway during significant weather events.

Over the lifecycle of construction, Central Government funded nearly $14m through the Department of Internal Affairs and the Ministry of Business, Innovation and Employment.

Regional Council Chair Doug Leeder acknowledged the collaborative effort to reach this milestone.

“This project would not have happened without the combined effort of the community, Ngāti Awa, the Regional Council, Whakatāne and Kawerau District Councils, and Central Government.

“These contributions are tangible recognition of the importance of regional New Zealand and, more specifically, the role the Eastern Bay of Plenty plays in the social and economic fabric of the wider region and the country.

“It also demonstrates the importance of listening to and working with ratepayers to develop and fund key infrastructure, particularly in an environment where the impact of climate change is increasingly ‘front and centre’ in decisions underpinning long term community resilience.”

Associate Regional Development Minister Mark Patterson said the project significantly strengthened the region’s infrastructure.

“This is one of the biggest flood resilience efforts completed in New Zealand in recent years. It will deliver vital protection for local communities and unlock economic potential across the Eastern Bay of Plenty.”

Regional Council Engineering Manager Mark Townsend says he is proud to see this project completed and thanks the teams involved for their mahi.

“Flood protection, such as the Spillway, is the first line of defence in a flood event. This is why the Regional Council continually invests in the management and maintenance of flood protection assets around the rohe.”

Mr Townsend says the key to doing this is an integrated approach by Regional Council’s engineering, assets and operations teams, as well as implementing best practise approaches and exploring innovation when it comes to engineering designs.

“The Spillway upgrade is a great example of what happens when you mix robust data and modelling with innovative engineering and community input. The design choices we have made will help ensure longevity of these assets.”

Now complete, the Rangitāiki Floodway and Spillway assets form part of a network of flood defences along the Rangitāiki River. This includes the recent upgrades to Rangitāiki River Floodwalls and Lower Rangitāiki Stopbanks at the river mouth near Thornton.

ENDS

History of the Rangitāiki River scheme

In the late 1800s and early 1900s European settlers sought to drain the Rangitāiki swamp and create farmland. Initial efforts began with the establishment of the Rangitāiki Drainage Board in early 1900s.

The Board directed numerous land drainage works and interventions to create the conditions for agricultural productivity to grow and thrive. These included diverting the river through a new channel near Thornton. This provided a direct outlet to the sea. A growing a network of drains and canals followed.

These early works allowed for new roads, bridges and rail infrastructure to be constructed, all fundamental to supporting the expanding eastern Bay of Plenty community and economy.

As agricultural benefits were realised other industries established, such as the Rangitāiki Plains Dairy Company, and the Edgecumbe township grew.

Due to the frequency and impact of river flooding events during the 1940s and 50s a system of stopbanks, canals and floodgates for flood protection were constructed, under the control of the Eastern Bay of Plenty Catchment Commission.

The initial scheme works between 1960s-1980s focused on stopbanking the Rangitāiki River between Te Teko and Thornton, and flood pump infrastructure. These works also included the very beginning of the floodway creation, via Reid’s Central Canal.

The next major development came with the construction of the Matahina Dam in the early 1960s, which provided the opportunity to regulate river flows from the upper Rangitāiki. The dam continues to play a significant role in managing river flows and reducing flood peaks downstream during high rainfall events.

The impact of the magnitude 6.5 Edgecumbe earthquake on 2 March 1987 had a major effect on flood protection infrastructure.

The earthquake caused extensive damage to stopbanks, drainage canals, and pumping systems across the plains. Stopbanks cracked and slumped, compromising their integrity. Drainage channels were disrupted by lateral spreading, ground deformation and changes in elevation.

The scheme faced another pivotal moment following flooding in 2004. This resulted in a decision and commitment to significantly modernise the floodway and spillway scheme. That work began in 2011, and the spillway marks the completion of the major capital works programme on the Rangitāiki River.