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Rangitāiki River – major upgrades to flood management infrastructure

The Rangitāiki River has a long history of flooding. While numerous flood management projects have occurred along the river since the 1960s, the last decade has involved Council working closely with the community to develop and deliver major upgrades to infrastructure, the most significant being the Rangitāiki River Floodway and Spillway.

Rangitāiki River Floodway and Spillway

Completed May 2025

The Rangitāiki Floodway and Spillway is a multi-stage project designed to take pressure off the Rangitāiki River in a flood event, by diverting some of its flow, via a spillway, into near-by farmland between stopbanks (known as the floodway) and out the Rangitāiki River mouth at Thornton.

This project involved increasing the floodway’s capacity and upgrading the existing spillway to provide more assurance during a flood event.

Find out more about the floodway and spillway.

Between the 1960s and 1980s, the Rangitāiki Floodway was created by the Eastern Bay of Plenty Catchment Commission to provide flood protection to the community in and around Edgecumbe.

Over time, the level of flood protection that the floodway offers had decreased, due to the impacts of a changing climate – plus, as technology has advanced, we can better predict what flood events may look like and how our flood defences need to be constructed to meet future demands.

Crown infrastructure funding

Regional Council receiving funding ($3.367M) in the early stages of this project through the Department of Internal Affairs. 

Additional funding was received for Stage 6 of the floodway and the spillway from Central Government’s Crown Infrastructure Funding for this project as part of the Climate Resilience Programme ($10.275M). This funding was granted as part of the Covid-19 Response and Recovery Fund, and was one of six projects Regional Council received funding for. 

Learn more about this funding.

Rangitāiki River floodwalls

Completed February 2024

The Rangitāiki River floodwall project saw three existing floodwalls at Greig Road, Thornton School and College Road removed and replaced with new, upgraded flood defences.

The new defences were constructed by inserting sheet piles (big sections of sheet steel with interlocking edges) into the ground and covering them with an earth stopbank or concrete floodwall. This design provides more effective seepage control.

Construction was completed in three stages:

  • Stage 1: Grieg Road (completed April 2021)
  • Stage 2: Thornton School (completed December 2021)
  • Stage 3: College Road (completed February 2024)

This project was prompted by the discovery of seepage (the slow escape of water through spongy earth) at three floodwall sites along the Rangitāiki River (Greig Road, Thornton School and College Road) and is part of Regional Council’s ongoing work to upgrade flood defences around the rohe.

Crown infrastructure funding

Regional Council received funding from Central Government’s Crown Infrastructure Funding for this project. This funding was granted as part of the Covid-19 Response and Recovery Fund. The funding covered 75% of the initial project cost and was one of six projects Regional Council received funding for. 

Learn more about this funding.

Lower Rangitāiki stopbank upgrade

Complete June 2024

We’ve upgraded around 1.25km of stopbanks along the lower Rangitāiki River (next to Thornton Beach Road).

The stopbank upgrades included:

  • Deconstructing the stopbanks and rebuilding them with suitable soil.
  • Raising the height of the stopbanks and the land level in the properties across the road.
  • Upgrading culverts.
  • Installing drainage. This involves building a trench at the base of the stopbank (land side) and filling it with drainage material (such as gravel). This will allow water to pass through in a controlled manner, and relieve the water pressure building up inside and under the stopbank.

The completed stopbank has been covered with a gravel layer to future-proof the infrastructure. This ensures the stopbank can support potential new developments, making the area more adaptable and durable for different recreational and transportation uses.

Flood protection assets (such as stopbanks) are periodically checked to ensure they are still fit for purpose to help reduce the risk of flood events on local communities.

Soil testing and computer modelling were undertaken on the flood defences along sections of the Rangitāiki River (awa).
Using this information, as well as what we know about climate change, several flood defences along the awa have been identified as needing an upgrade – including this stretch of stopbanks along Thornton Beach Road. 

This upgrade addressed the identified issues in the stopbank and ensured these defences can continue to reduce the impacts of flooding on the community, now and into the future.