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The Condition of 41 Lakes in the Waikato Region Using LakeSPI

TR 2007/35
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Report: TR 2007/35

Author: Tracey Edwards, John Clayton, Mary de Winton (NIWA)

Abstract

NIWA was contracted by Environment Waikato to assess the condition of forty-one lakes using LakeSPI; a method that uses Submerged Plant Indicators (SPI) to assess, monitor and report on lake condition. LakeSPI assessments were carried out on each lake to describe:

  • Pristine condition (lake plant communities in pre-impacted times).
  • Historical condition (lake condition as described by historical data).
  • Present day condition (most recent data).

Lakes in the Waikato region were chosen to develop and apply indicators. Phase 1 of the project included lakes for which NIWA held data and for which significant changes were not expected, therefore no site visits were required. This phase was completed in December 2003 (Edwards and Clayton 2003). Phase 2 included selected additional lakes that required surveys to provide an up-to date assessment and was completed by December 2005 (Edwards et al. 2005). Phase 3 has seen the addition of a further 12 lakes and brings the total of lakes reported here to forty-one.

The study brief also required all lakes to be placed into one of the following categories: “excellent”, “satisfactory” or “unsatisfactory” based upon their current day condition.

LakeSPI indices for these Waikato lakes will provide valuable inter-lake comparisons and enable long term monitoring of future changes in their condition. For lake managers, LakeSPI provides relevant information for regional and national reporting requirements and can be used to help assess the effectiveness of catchment and lake management initiatives.

The Condition of 41 Lakes in the Waikato Region Using LakeSPI [PDF, 328 KB]

Contents
  Executive Summary v
1. Introduction 1
1.1 Study brief 1
2.   2
2.1 History of the Waikato lakes 2
2.2 Lake vegetation changes 3
2.3 Plants as indicators of lake condition 5
3. Study methods 6
3.1 LakeSPI 6
3.2 Baselines 7
3.3 Information sources 8
3.4 Study lakes 8
4. Results 12
4.1 Lake Areare 12
4.2 Lake Hakanoa 13
4.3 Lake Harihari 13
4.4 Lake Hinemaiaia (B) 14
4.5 Lake Hotoananga 14
4.6 Lake Kainui (D) 15
4.7 Lake Kimihia 15
4.8 Lake Kaituna (B) 16
4.9 Lake Koromatua 17
4.10 Lake Mangakaware 17
4.11 Lake Mangahia 18
4.12 Lake Ngahewa 18
4.13 Lake Ngaroto 19
4.14 Lake Ohinewai 20
4.15 Lake Okowhao 20
4.16 Lake Opouri 21
4.17 Lake Otamatearoa 21
4.18 Lake Parkinson 22
4.19 Lake Pataka 23
4.20 Lake Posa 23
4.21 Lake Puketi 24
4.22 Lake Rotoaira 24
4.23 Lake Rotoiti 25
4.24 Lake Rotokauri 26
4.25 Lake Rotokawau 26
4.26 Lake Rotomanuka 27
4.27 Lake Rotongaro 27
4.28 Lake Rotongaroiti 28
4.29 Lake Rotopounamu 28
4.30 Lake Rotoroa 29
4.31 Lake Ruatuna 30
4.32 Lake Serpentine East (Rotopiko East) 31
4.33 Lake Serpentine North (Rotopiko North) 31
4.34 Lake Serpentine South (Rotopiko South) 32
4.35 Lake Taharoa 33
4.36 Lake Taupo 33
4.37 Lake Tunawhakapeka (E) 34
4.38 Lake Tutaeinanga 35
4.39 Lake Waahi 35
4.40 Lake Waikare 36
4.41 Lake Whangape 36
5. Discussion 38
6. Recommendations 43
7. References 44