River ecology in Tāmaki Makaurau: Annual data summary 2025

Author:

Graham Surrey

Source:

Auckland Council Environmental Evaluation and Monitoring Unit, EEMU

Publication date:

2025

Topics:

Environment

Auckland Council's online interactive Water Quality and River Ecology Data Explorer presents State of the Environment (SoE) monitoring data for rivers, lakes, groundwater and the coast. Groundwater quality data can be compared across the region, between aquifers and over time.¹

This report provides a summary of river ecology monitoring results for the period July 2020 to June 2025, or 2021-2025 based on the hydrological year.

Key findings

Land use impacts stream ecological health

Stream ecological health was generally poorest in urban streams and best in streams within catchments dominated by either exotic or native forest.
The macroinvertebrate communities within forested streams were dominated by pollution-sensitive taxa, indicating high water quality.
Urban streams contained mainly pollution-tolerant macroinvertebrates due to poor water and habitat quality. This is reflected in lower ecological metric scores.

The majority of monitoring sites had either 'excellent' or 'good' SEV scores

Sixty-nine percent of sites had median Stream Ecological Valuation (SEV) scores that placed them within either the 'excellent' or 'good' categories for ecological value. This compares to 49% of sites that were rated as 'excellent' or 'good' for the MCI metric and 28% for QMCI, reflecting differences in the attributes measured.

Urban streams had the worst overall ecological quality

Nine of the 10 worst-ranked sites across all ecological metrics were located in urban catchments, with Ōmaru Creek, a soft-bottomed urban site in Glen Innes, ranking as the worst overall.

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1. This does not include the detailed statistical analysis that is required to assess trends in water quality over time and is reported in our five-yearly State of the Environment reports.

Auckland Council, December 2025