Te Heriheri Wetland System

Overview

Metis Consultants partnered with the Bay of Plenty Regional Council (BOPRC) to design and deliver a nature-based solution to improve water quality in the Waihī Estuary. As part of its Sustainable Land Use Incentives (SLUI) programme, BOPRC prioritised the wider Waihī Estuary Catchment—a 35,000-hectare system impacted by intensive agricultural land use. The lower catchment is dominated by dairy farming on low-lying land, where nutrient-rich runoff is pumped through canal networks before discharging to the estuary.

The Challenge

Elevated levels of nutrients, sediment, and E. coli were degrading water quality in a sensitive receiving environment. These pressures not only affected ecological health but also cultural values and recreational use of the estuary.

BOPRC required a solution that was practical, cost-effective, and capable of delivering measurable improvements at scale—without disrupting existing land use.

Our Approach

Metis was engaged to assess water quality improvement options across the lower catchment. Our feasibility study identified freshwater treatment wetlands, strategically located upstream of pump stations, as the most effective intervention. Following land acquisition at Cutwater Road by BOPRC and a local iwi collective, we led a second-stage feasibility study confirming the viability of an integrated freshwater–coastal wetland system. Close collaboration with stakeholders, including local farmers and iwi partners, helped shape a solution that balanced environmental performance with cultural and community outcomes. We then supported the project to progress efficiently through detailed design, consenting, and construction.

Solution

Metis delivered the full project lifecycle—from feasibility and concept design through to detailed design and construction support. The final system includes:

• 27 ha freshwater treatment wetland
• 3 ha coastal wetland
• Inlet and outlet control structures
• New pump station integrated with the canal network
• Public access features

Outcomes

The system now treats runoff from over 600 hectares of intensively farmed land, significantly reducing nutrients, sediment, and microbial contaminants before discharge to the estuary. It also enhances habitat diversity, supporting native wetland species and improving overall ecosystem resilience.

Impact

This project demonstrates how targeted, catchment-scale investment in engineered natural systems can deliver measurable water quality improvements while restoring ecological function. The Te Heriheri Wetland is now a flagship example of integrated catchment management—combining environmental performance, cultural partnership, and community value in a single, enduring solution.