Case Studies

Pokaiwhenua Catchment

The Pokaiwhenua Catchment Group formed in early 2021. The group governance structure is set up as a trust, with the trustees formed from local community, Iwi and business representatives. The group’s vision is “to restore and enhance the wellbeing of the Pokaiwhenua catchment for the benefit of the community”. The group’s strategic plan includes seven interconnected objectives focussed on water quality, biodiversity, cultural and community goals.

The Pokaiwhenua catchment is in the south Waikato region andincludes the townships of Tokoroa and Putāruru. The Pokaiwhenua stream originates in the hills of the Mamaku Plateau and ends at Lake Karapiro, eventually draining into the Waikato River.

The aim of the case study was to test the WebApp in the context of the Pokaiwhenua catchment and, in working with the catchment community, develop monitoring recommendations to assess the freshwater restoration outcomes of the Pokaiwhenua action plan, using both biophysical and mātauranga Māori tools.

The development of a cultural monitoring framework focused on rejuvenating traditional Raukawa mahinga kai practices to monitor freshwaters within the Pokaiwhenua catchment. It involved integrating both science and mātauranga Raukawa to inform better practice monitoring methods. The reestablishment of a Pā Tuna site on the Pokaiwhenua was initiated as part of a monitoring plan.

The Pā Tuna project monitoring plan draws on Te Ārohirohi a Raukawa (Raukawa’s freshwater assessment tool) which guides kaitiaki on how to conduct freshwater assessment initiatives as aligned with Raukawa tikanga, values and philosophies.

The biophysical monitoring section focused on assessing the performance of the current monitoring network to detect improvements in water quality indicators over time including those required by the Waikato Regional Plan Change 1. Further, the case study demonstrates the capability of the WebApp to customise the underlying land mitigation layer to test different mitigation scenarios. Two mitigation bundles were developed with farmer input for this purpose. Each mitigation bundle was based on the likelihood of application and considered elements of cost, opportunity, and existing knowledge.

Read the full report here

More information on this project:

• Visit the Pokaiwhenua Catchment Group website
• Te Mana o Te Wai Case Ruakawa case study
• Te Ārohirohi o Raukawa - Raukawa Freshwater Monitoring Framework video
• Te Ārohirohi a Raukawa (Raukawa’s freshwater assessment tool) - This publication is available to Raukawa iwi members only, to request a digital copy please email environment@raukawa.org.nz

Selwyn Waihora Zone

Te Waihora/Lake Ellesmere is a hāpua (a shallow, brackish coastal lake-lagoon). It is the largest in Waitaha Canterbury, fifth largest in Aotearoa/New Zealand, and an important wildlife area both nationally and internationally. Whakaora Te Waihora is an extensive ecological and cultural restoration programme underway now.  For Ngāi Tahu, Te Waihora has outstanding significance as a tribal taonga, representing a major mahinga kai/food resource and an important source of mana tewaihora.org.

Over the years, flows in lowland streams and the Waikirikiri/Selwyn River have decreased, while nitrate concentrations have increased, and the health of Te Waihora/Lake Ellesmere has deteriorated. About 200 farms in the area are required to reduce their nitrogen loss from 1 January 2022. Read more

The purpose of our case study was to assess whether the current SoE monitoring network is likely to detect water quality improvements associated with regional plan rules (Plan Change 1 of the Canterbury Land and Water Regional Plan. The key findings of our study were as follows:

• The current monitoring programme is not well suited to detecting reductions in nitrate at the scale required by PC1.
• It will likely be 30 or more years before PC1 reductions can be detected by the current monitoring regime.
• Obtaining water age data for all key monitoring sites, particularly in surface water courses, is a key recommendation.
• There is a trade-off between the scale of NO₃-N mitigations and the cost of the monitoring programme required to detect the effectiveness of these mitigations. Very large mitigations are easy to detect, but may not be realistic for other reasons. Smaller mitigations are typically more tenable, but require a more expensive monitoring programme to detect.
• Our report shows that bespoke monitoring programmes may often be required to assess the effectiveness of a plan change. We suggest that an analysis of an effectiveness monitoring programme and its cost should be a component of the plan change itself.
• Finally, detecting PC1 or similar changes requires a significant investment in monitoring infrastructure and data collection

Read the full report here