Ngati Haua Piako: review of information available for freshwater resource management in the Piako River Catchment within Ngati Haua rohe

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Rawlinson, Z.J.; Gardiner, L. 2019 Ngāti Hauā Piako: review of information available for freshwater resource management in the Piako River Catchment within Ngāti Hauā rohe. Lower Hutt, N.Z.: GNS Science. GNS Science report 2019/35. 96 p.; doi: 10.21420/7HGH-RQ33


The Ngāti Hauā Piako Programme (NHP) is a collaborative programme between Ngāti Hauā Iwi Trust (Ngāti Hauā) and GNS Science that spans the period from May 2017 to May 2019. NHP aims to facilitate the sharing of resources and knowledge to enable Ngāti Hauā to make informed decisions regarding freshwater resource management in the Piako Catchment, Hauraki. Ngāti Hauā aspires to improve the health and vitality of the Piako River to ensure the mauri of the waterways is sustained for future generations. This requires informed decision making that constitutes a merger of scientific knowledge with Mātauranga Māori and cultural values. The geographic scope of this work is within the area intersection of the Piako River Catchment and the Ngāti Hauā Rohe (hereafter, termed Ngāti Hauā Piako). This report collates and summarises data and information of relevance to freshwater in Ngāti Hauā Piako, with a focus on groundwater; as well as key information from mātauranga-a-iwi gathering. The summarised data sets have been provided to Ngāti Hauā to enable further use. In Ngāti Hauā Piako, surface water is over allocated, both based on scientific estimation and on Ngāti Hauā oral tradition, which describes a reduction in depth and flow of surface water in the area. The groundwater resource is extensive and there are many bores accessing groundwater in the area. Current management limits in the area considers the groundwater resource only 4% utilised. Scientific information, however, also describes the strong link between surface water and groundwater – with significant amounts of surface water expected to be sourced from groundwater discharge. Sustainable yield for groundwater has not yet been estimated for the area, and such an estimation would need to consider the joint freshwater resource (groundwater and surface water together). In Ngāti Hauā Piako, surface water quality is poor, with both scientific estimation and Ngāti Hauā oral tradition describing the worst contamination as having occurred pre-1990s (before scientific environmental monitoring began in the area). This quality has a small improving trend, with modern contamination loads (post 2006) mostly being a result of agricultural landuse, and the improving trend likely to be from improving farm management practices. Groundwater quality is variable, but at several monitored locations nitrate levels are above or above half of the drinking water guideline values (often considered a management trigger level at which intervention is needed). The changed freshwater resource has had a significant effect on Ngāti Hauā’s traditional way of life. There used to be extensive kai resources; the rivers were used for swimming, drinking water and for baptisms. Traditional recreation, Tikanga, and gathering of kai related to freshwater resources are all no longer available. Recent national policy within New Zealand directs that regional management plans will be put in place by 2030 to ensure that national bottom-line freshwater quality and quantity targets are met, and that where they are currently not met, steps are put in place to work to improve the resources. Waikato Regional Council is starting a plan change process in 2019 that includes the Ngāti Hauā Piako area, with the intention to bring changes to freshwater management in the area to address current issues. For example, to better address the integrated nature of catchment water resources with respect to allocation. (auth)