Monitoring & Mauri
Monitoring freshwater in Linkwater
Water quality in streams, rivers, lakes and wetlands are all highly influenced by surrounding land use. In Te Hoiere where native vegetation dominates, water quality is usually good. However, pastoral land use and production forestry have caused water quality in some catchments to degrade with sediment, E.coli and nitrogen as the main contributors. Project partners undertake a range of monitoring activities to assess the cultural and ecological health of Te Hoiere's waters and biodiversity that depends on it. Monitoring activities assess baseline health of freshwater, as well as changes over time, especially where Project partners and the community are working towards land management practices to improve water quality.
Cultural Health Monitoring
Ngāti Kuia, with support from Our Land and Water, has developed a tool to assess the mauri of restoration efforts in Te Hoiere, especially Ruapaka Wetland. As one of the aspirations woven into Te Hoiere Project, the team researched other cultural health monitoring tools in Aotearoa to design a unique one that upholds Ngāti Kuia values. The tool, Te Kupenga ā Kuia Mauri Assessment, aims to provide a unique Ngāti Kuia perspective on the health of te taiao, enabling tangata whenua to record and monitor changes over time. This will allow Ngāti Kuia to track the effectiveness of their restoration efforts. Ngāti Kuia has trialled monitoring techniques that may complement Te Kupenga ā Kuia, including the use of eDNA tests to trace the presence of species in the water. Testing has shown the presence of dwarf galaxias, shortfin tuna, inanga, and grey teal. Ngāti Kuia have used the same methods in the Whakamarino (Wakamarina) as well, showing the presence of various taonga species which all builds a baseline knowledge of each wai.
Read more about this work with Our Land and Water here.
Mitigation Monitoring
At the start of Te Hoiere Project, Marlborough District Council and the community carried out intensive water quality studies to support decision making about where to focus restoration efforts. A follow-up study has assessed how mitigation activities, such as fencing, planting natives, dung beetles and changes to land management practices, are influencing water quality. The 2025 Mitigation Effectiveness Monitoring Report shows measurable progress towards the Project’s aspiration Oranga Wai – waterways are healthy and resilient.
Initiated in late 2023, the monitoring programme assessed nine sites across Te Hoiere/Pelorus catchment, comparing current water quality data to Marlborough District Council's 2020/21 baseline water quality study. Improvements have been most evident at sites with extensive fencing and riparian planting. One site near Rai Valley showed significant decreases in nitrate, ammoniacal nitrogen and phosphorus levels, which aligned with large-scale fencing and planting. Other sites in Linkwater and lower Te Hoiere are showing improvements, likely through proactive land management and new farm practices.
Read more about the Rai Valley farm case study.
Water Quality in the Te Hoiere Catchment Restoration Project Area – A Summary of Baseline Monitoring
Te Hoiere Water Quality Mitigation Effectiveness Monitoring Report 2025
Shown below, mitigation monitoring includes sampling for vertebrates.
Ecological Integrity
Department of Conservation collects environmental monitoring data as part of the Ngā Awa river restoration programme. Eleven sites on public conservation land were used to measure indicators of ecological integrity.
Ecological integrity measures the health of an ecosystem by considering how native, pristine, diverse and resilient it is. This monitoring looked at indicators and measures of integrity classed into three high-level categories:
- aquatic life (including fish, macroinvertebrates, megainvertebrates, aquatic plants and periphyton)
- habitat (including habitat types, discharge, substrate stability and deposited sediment)
- water quality (including nutrients, other water chemistry data and visual clarity / suspended sediment).
All results indicated good water quality and that the catchment within public conservation land is a good point of reference for restoration efforts in other areas of the catchment. Aquatic life scores suggest there is high biodiversity across the sites. Similarly, the habitat and water quality measures were generally indicative of pristine conditions.
Ngā Awa Monitoring Programme: Te Hoiere Catchment Reporting 2021–22
Below: Photos show biodiversity monitoring in Te Hoiere by Cawthron Institute; six native and two introduced species were caught using electric fishing, including tuna (longfin eel) pictured here
Below: These photos were not taken in Te Hoiere, but show the techniques used by scientists to measure indicators of ecosystem health: eDNA collection, electric fishing, and periphyton cover assessments
Sediment Monitoring
Motuweka/Havelock Estuary is one of the muddiest estuaries in New Zealand. However, fine sediment cover isn’t a major problem within the freshwater channels of Te Hoiere catchment that flow into the estuary, likely because of the steep gradients in the river system. During floods, however, significant amounts of fine sediment are seen over short periods when substantial amounts can be carried through the system and eventually settle on the bed of the estuary.
A plan to monitor sediment in Te Hoiere catchment surfaced in 2023 to better understand the sources and to quantify sediment loads from sub-catchments. This plan will measure sediment loads through continuous turbidity monitoring, coupled with continuous flow measurements and targeted water sampling for concentrations of suspended sediment.
Four monitoring stations will be used to measure sediment coming from Rai, Upper Te Hoiere, Whakamarino (Wakamarina), and Kaituna. In Lower Te Hoiere, the tidal nature of flows makes continuous flow measurements difficult for the purpose of obtaining sediment loads.
Since new monitoring equipment can be costly, three of the four locations were chosen to take advantage of existing monitoring infrastructure run by Marlborough District Council and Earth Sciences NZ (formerly known as NIWA).
This project to monitor sediment will run across four phases:
- Phase 1: Turbidity sensors installed (2024 & 2025)
- Phase 2: Sediment monitoring to establish relationship between turbidity and sediment concentration (In progress)
- Phase 3: Identify main flow conditions and sub-catchments with the largest contribution to sediment loads
- Phase 4: Explore and implement mitigation measures to reduce sediment loads
Continuous measurements of flow and turbidity offer several advantages in estimating sediment loads. First, this enables real-time monitoring and provides a more comprehensive understanding of sediment dynamics, particularly during episodic events such as floods or changing environmental conditions. Continuous data sets also enable quicker detection of trends, patterns, and changes over time, providing valuable insights into sediment transport processes.
While the first two phases are funded by Te Hoiere Project, the third phase will be completed with existing resources at Marlborough District Council, combining previous work from Project partners relating to catchment and sediment understanding. Funding for the fourth phase is currently unknown, as it will depend upon the outcomes in previous phases.
Shown above, Marlborough District Council checks the calibration of newly installed turbidity sensors.
