The Ahuriri Estuary/Te Whanganui a Ōrotu is a nationally-significant Wildlife Refuge, home to diverse flora and fauna, and is a vital wetland ecosystem under constant pressure from urban untreated stormwater, invasive pests, rural nutrient run-off and sediment, and commercial/industrial toxin impacts.

The Ahuriri Regional Park Stormwater Project proposal, in association with the Ahuriri Regional Park Project, promises to address the challenges of untreated stormwater.

As we understand it, the core objective of the Stormwater proposal is the cleaning of the untreated Napier stormwater going into the estuary. This will be done within the 284 hectares of NCC-owned farm land (Lagoon Farm). The man-made wetlands (85 hectares) will be filled with extensive native plantings designed to filter urban stormwater before it enters the estuary. 

Surrounding the proposed wetland, a multi-faceted recreational area has been designed on the remainder of Lagoon Farm, from Prebensen Drive to the Ahuriri Estuary channel. 

While the whole proposal emphasizes ecological restoration, the inclusion of certain ‘passive’ recreation on the estuary channel, including visitor hub with toilet, a kiosk, towers, and waka landings, introduces risks of increased human disturbance to the wildlife sensitive habitats. We have previously witnessed the negative impacts of human disturbance on bird nesting areas.

As our organisation follows the process with interest, and digs deeper into the progress of the wetland plans, we discover there are huge challenges to getting all polluted stormwater discharges into the new wetland, e.g. The Taipō, the Old Tutaekuri Riverbed, the County, and Plantation – discharging continuously by pump, and which are known to carry high loads of hydrocarbons, heavy metals, sediment, e-coli, nitrates, and consistently-elevated phosphorus. So far, the only waterway able to be easily connected to the new wetlands appears to be the relatively-cleaner Pirimu catchment. 

Without comprehensive treatment of all major in-flows, the estuary will continue to receive daily loads of toxic contaminants, putting birdlife, aquatic species and the overall ecosystem health at further risk. How will this be achieved? 

From an environmental perspective, the Ahuriri Regional Park Stormwater project proposal represents a significant step towards protecting and restoring the water quality of the estuary. Transforming farmland into native wetlands to treat stormwater is a proven approach that should reduce pollution and enhance biodiversity. Its soundness will depend on:

• strict limits on recreational access to sensitive wildlife areas in the neighbouring estuary channel
• ongoing monitoring and adaptive management of wetland performance
• strong, unified governance focused on ecological outcomes above all else.

If these conditions are met, the Ahuriri Regional Park could become a model for urban wetland restoration and estuary protection.

The Ahuriri Estuary Protection Society supports the Ahuriri Regional Park proposal in principle, but urges the decision-makers to keep environmental priorities at the forefront, ensuring the health of the Ahuriri Estuary (Te Whanganui a Ōrotu) is never compromised for convenience or recreation. The proposal must intercept and treat the high risk discharges of stormwater to be truly beneficial, and ensure wildlife are not ‘squeezed out’ by human disturbance.