On 6 April 2017, the Rangitāiki River breached a stopbank at College Road, Edgecumbe resulting in the flooding of much of the township. Around 15 houses were rendered permanently uninhabitable, and more than 250 other homes had to be evacuated to allow for the required repairs.

On 10 April 2017, the Bay of Plenty Regional Council commissioned an independent review to provide answers to the people of Edgecumbe and the wider Eastern Bay of Plenty about what happened and why. The review panel was chaired by Sir Michael Cullen and its report “Rangitāiki River Scheme Review – April 2017 Flood Event” (Report) was made public on 3 October 2017.

The Report highlights the challenges faced by councils in managing natural hazards, the needs and concerns of local communities, and the application of limited resources to meet those challenges. It records that “there is no reason to believe that any of those involved did anything less than their best”.

Strategic themes

Three strategic themes emerge from the Report, which have relevance for other councils tasked with managing the interface between communities and the natural environment:

• Scheme sustainability and climate change: the Rangitāiki River Scheme has been in place since the 1960s. Such schemes may need to be updated, particularly in light of the increased challenges posed by climate change and an increase in extreme weather events. The Report notes that “making room for rivers” may be the best way of managing rivers in future.

• Leadership and governance: the Report emphasises the importance of raising community awareness of the risks associated with living on a flood plain, and managing the sustainability of current lifestyles in light of those risks.

• Converging worldviews: a distinction is made between the Māori (existing with the natural state of the river) and Pākehā (flood protection) world view, and suggests that both need to come together to best manage the river.

Circumstances leading to the breach

The breach of the stopbank on 6 April 2017 followed periods of heavy rain in the Bay of Plenty between February and April, culminating in Cyclone Debbie hitting the region around 3 April.

The panel concluded that there was not one single attributable factor that caused the breach. The reasons for the breach are complex. The concrete floodwall itself did not fail. Instead, it is likely that water found its way through the material forming the stopbank and did not then dissipate via the drainage system, as intended. This caused water pressure to build underneath the floodwall, which eventually caused the cribwall to shear off and move inland, and the resulting breach.

The Report considers other aspects of the Rangitāiki River Scheme that may have contributed to the volume of water in the Rangitāiki River at the time of the breach. For example, the panel concluded that Trustpower managed the level of the upstream Lake Matahina dam in accordance with the applicable Flood Management Plan, and it is unlikely that any further drawdown – and lower lake level – would have prevented the failure of the stopbank at College Road. The development of Reid’s Floodway is also discussed at length in the Report. The Floodway was a major feature of the flood protection structure, and an enlargement of it was still being undertaken as at April 2017.

The report makes 29 recommendations, relating to: the legal and planning framework for flood hazard management, the Floodwall itself, the operation of the Matahina Dam, evacuation planning, long term strategy and design philosophies, and community engagement. We understand that many of the recommended actions were already being undertaken by the Bay of Plenty Regional Council at the time that the Report was released.

Conclusion

It is plain from reading the report that there are a myriad of factors and competing considerations that are relevant to the Bay of Plenty Regional Council’s decision making. During the flood event, Council staff were under enormous pressure, working around the clock to manage the river for the community while many of their own homes and families were directly affected.

We understand that the Council is continuing to repair damage from the April flood event, and to work with the community to ensure that it is sufficiently informed of and protected from the risks of living next to the Rangitāiki River.

Rice + Co advised the Bay of Plenty Regional Council throughout the independent review process, including on fact-gathering exercises, issues associated with insurance cover, and legal risk arising from the indicated class action.