Auckland lake assessments 2024

Author:

Ebrahim Hussain, Submerged Environmental Ltd

Source:

Auckland Council Environmental Evaluation and Monitoring Unit, EEMU | Submerged Environmental Ltd

Publication date:

2025

Topics:

Environment

Auckland Lake Assessments 2024

Executive summary

Auckland Council contracted Submerged Environmental to assess the ecological condition of eleven lakes using the Lake Submerged Plant Indicators (LakeSPI) methodology. These assessments are part of the council’s statutory environmental monitoring requirements and were completed between November and December 2024.

Across the 11 surveyed, 18% (Rototoa and Pokorua) were classed as being in high ecological condition, 9% (Whatihua) in moderate condition, 36% (Pupuke, Ōkaihau, Kawaupaku, and Kuwakatai) in poor condition and 27% (Spectacle, Slipper, Tomorata, and Te Kanae) in a non-vegetated state.

A comparison in LakeSPI score between the two most recent assessments indicate that two of the lakes (Whatihua and Kuwakatai) are likely in a declining state. Two lakes (Pupuke and Ōkaihau) showed signs of improvement, and the remaining seven lakes are in a stable state with nominal shifts in the overall LakeSPI scores.

None of the surveyed lakes achieved an A band for either of the NPS-FM 2020 National Objective framework Native Condition Index and Invasive Impact Index attributes. Lakes Pokorua (B band) and Rototoa (C band) were the only lakes that scored above the national bottom line for the Native Condition Index attribute, the remaining 82% of surveyed lakes were all in D bands.

All the vegetated lakes except for Rototoa (B band) and Kuwakatai (D band) scored C bands for the Invasive Impact Index attribute. This attribute does not apply to non-vegetated lakes (Slipper, Spectacle and Tomorata), so no banding is presented.

Auckland lakes face multiple threats including invasive species (macrophytes and fish), poor riparian buffers, eutrophication, climate change and extreme weather events.

The 2024 Auckland Lakes Assessment highlights the need for site specific lake management plans aimed at maintaining the current high value lakes and restoring the impacted lake where possible. Suitable monitoring programs should be developed in tandem to ensure accurate impact identification and intervention effectiveness.

Auckland Council, Submerged Environmental Ltd

September 2025