Catchment riparian characteristics survey of the Matahuru catchment 2024/25

Riparian margins occur along the interface between land and water and provide several important ecosystem functions, including filtering of contaminants, stabilisation of stream/riverbanks, and biodiversity values.

 Across New Zealand, land use intensification has resulted in large scale clearance of riparian vegetation, impacting on both the hydrology and water quality of the receiving environment. The Waikato Regional Council (WRC) has actively promoted enhanced management of riparian margins through initiatives such as Project Watershed (2002 – current), the Clean Streams project (2002 – 2010) and through the development and implementation of catchment management plans such as the Waipā Catchment Plan (WCP) and Waikato and Waipā River Restoration Strategy (Neilson et al., 2018).

To monitor the effectiveness of soil conservation work for improving water quality outcomes, WRC established the Catchment Environmental Monitoring (CEM) programme in 2003. An important part of the CEM programme is the monitoring of riparian margins across priority catchments to track changes in riparian characteristics over time and to assess the effectiveness of initiatives implemented by council, iwi, landowners, industry partners, and key co funders such as the Waikato River Authority (WRA).

The Matahuru catchment is situated in the Lower Waikato Catchment Management Zone (CMZ) and has a catchment area of approximately 11,000 ha. The main waterway is the Matahuru stream which flows the length of the catchment before draining into Lake Waikare. The Waikato Regional Council identified the Matahuru catchment as a ‘high priority’ catchment, mainly due to water quality concerns related to phosphorus (P), E. coli, and sediment. Furthermore, the catchment was marked as a high priority for hill-country erosion control and river management under the collaborative Waikato and Waipā River Restoration Strategy. This strategy, led by WRC, WRA, DairyNZ, and iwi (Neilson et al., 2018), acknowledges the significant sediment contributions from the Matahuru and surrounding catchments to Lake Waikare and the Waikato River.

To assess the current state of riparian margins across the catchment, a riparian survey was undertaken during the summer of 2024/2025, involving field assessments at 50 representative sites. Examples of monitored riparian characteristics include extent of fencing, stock access, buffer width, vegetation type and extent, and streambank erosion.

This report presents the findings from the most recent catchment-wide riparian characteristics survey in the Matahuru catchment, carried out during the summer of 2024/2025 (referred hereafter as the ‘2024 survey’).

A previous catchment wide survey was undertaken in 2020/2021.

Report: TR 2024/27

Author: Tim Norris