Mataura flood infrastructure upgrade
These upgrades strengthened priority parts of Mataura’s flood-infrastructure network, reducing flood impacts on homes, businesses and essential services. The works support reliable performance during high flows and help sustain agreed service levels as climate pressures increase.
In February 2020, floodwaters tested Mataura’s flood banks to near capacity and about 1,500 residents were evacuated. Alongside planned upgrades to the Boundary Creek and Waimumu Stream flood banks, engineering assessments identified sections of the main Mataura River flood banks that required urgent reinforcement to address erosion ahead of the next high-flow period.
Key upgrades completed
- Strengthened and extended the Boundary Creek flood bank.
- Reinforced the Waimumu Stream flood bank.
- Added rock armouring to vulnerable sections of flood bank along the Mataura River upstream of Te Au Nui Pīhapiha Kanakana / Mataura Falls.
- Removed high-risk trees on and immediately adjacent to flood banks.
- Extracted gravel from the gravel island in Mataura township to reduce riverbed build-up and improve channel performance.
Why these upgrades matter
Engineering assessments in November 2022 found that high flows in the Mataura River could drive bank erosion and elevate the risk of flood bank failure on the true left upstream of the former paper mill. The upgraded flood banks are built to allow future height adjustments, helping sustain agreed levels of service as climate pressures increase.
Removing trees and shrubs from flood banks reduces the risk of roots weakening the structure and of windthrow ripping out root balls that leave holes or gaps in the bank. It also lowers the chance of woody debris damaging infrastructure during floods.
Benefits
- Reduced flood impacts for Mataura’s people, property and essential services.
- Future-ready design that allows for staged adaptations as needs change.
- Co-funded with central government (Kānoa), bringing work forward from the Long-term Plan and lowering costs for ratepayers.
What's next
On 16 October 2025, central government confirmed new co-funding through Kānoa – the Regional Economic Development & Investment Unit (MBIE) under the national Resilient River Communities initiative. This supports the next phase of work in Mataura: the Mataura River Flood Resilience Project.
This phase includes applying 2D hydraulic flood modelling across the Mataura River (including Mataura, Gore and Wyndham). The modelling will assess existing flood bank capacity and performance, identify priority improvements and inform the development of an integrated, whole-of-catchment plan for the river system.
Building on insights from Murihiku Slow the Flow, the plan will test how engineered and nature-based measures can work together to reduce flood impacts. Nature-based measures such as wetland restoration, detainment bunds, floodplain reconnection and riparian planting can help slow, store and safely convey water while supporting ecological, cultural and community outcomes.
Insights from modelling and community engagement will guide the design and sequencing of future flood infrastructure works and longer-term adaptation options.
Funding
This project is part of the national Resilient River Communities initiative — a joint programme between Kānoa and Te Uru Kahika – Regional and Unitary Councils Aotearoa. It is one of Environment Southland’s RRC projects, delivered with central government co-funding during 2021–2024.
