Project Start Year: 2026
The Lower Piako River Stopbank Upgrade addresses challenges to maintaining existing levels of service of the stopbank on the true right of the river. These stopbanks were built primarily in the 1960s and are experiencing increasing pressure from riverbank erosion, sediment build-up in the riverbed, and frequent tidal inundation of the berms.
Works include raising stopbank crests to provide protection from events with a 1% annual exceedance probability (AEP, likelihood of a flood of this magnitude happening in a given year), shifting some sections of stopbank away from the river’s edge to improve their long-term stability, and increasing berm width and height to sit above the spring tide level.
The project will reduce the risk of localised flooding and stopbank failure, helping protect the communities of Pipiroa and Ngātea, surrounding high value production rural land and critical infrastructure.
Benefits
Upgrading the stopbank will provide the continued direct protection of:
- 2016ha of rural productive farmland (approximately $149.5m capital value)
- Ngātea and Pipiroa townships
- State Highways 2 and 27, which are key lifelines to Thames and the Coromandel Peninsula and part of the "Golden Triangle" between Auckland, Hamilton and Tauranga
Construction will be delivered by local contractors, providing local economic and employment benefits.
Adaptation and resilience
The Piako River catchment has around 20,000ha of land below tide level and a further 100,000ha of low-lying land vulnerable to flooding.
Rising water levels on stopbank berms – a result of sediment buildup on the riverbed and higher tides – contribute to stopbank destabilisation.
The project increases the resilience of the stopbanks between Ngātea and Pipiroa by strengthening their foundations and upgrading sections that do not meet the required level of service.
This in turn supports continued community resilience to flooding by reducing risk of stopbank failure.
Collaboration
This project has been co-funded through the Regional Investment Fund (RIF) and Waikato Regional Council, reflecting a shared commitment to protecting people, property, productive land and critical infrastructure across the Waikato.
The Lower Piako Stopbank Upgrade project maintains the current flood protection level of service, ensuring continued protection of people, property, productive farmland and State Highway lifelines from a 1% annual exceedance probability event (AEP, likelihood of a flood of this magnitude happening in a given year).
This project prevents the need for permanent restrictions on land use and the relocation of buildings and infrastructure, including bridges and roads.
