Waikato Regional Council Technical Report 2014/59 Waikato region shallow lakes management plan: Volume 2 Shallow lakes resource statement: Current status and future management recommendations www.waikatoregion.govt.nz ISSN 2230-4355 (Print) ISSN 2230-4363 (Online) Prepared by Tracie Dean-Speirs & Keri Neilson (Waikato Regional Council) with input from Paula Reeves (Wildland Consultants) and Johlene Kelly (Alchemists Ltd.) For Waikato Regional Council Private Bag 3038 Waikato Mail Centre HAMILTON 3240 10 October 2014 Document #: 2256414 Approved for release by Clare Crickett Date May 2015 Disclaimer This technical report has been prepared for the use of Waikato Regional Council as a reference document and as such does not constitute Council’s policy. Council requests that if excerpts or inferences are drawn from this document for further use by individuals or organisations, due care should be taken to ensure that the appropriate context has been preserved, and is accurately reflected and referenced in any subsequent spoken or written communication. While Waikato Regional Council has exercised all reasonable skill and care in controlling the contents of this report, Council accepts no liability in contract, tort or otherwise, for any loss, damage, injury or expense (whether direct, indirect or consequential) arising out of the provision of this information or its use by you or any other party. Doc # 2256414 Page iii Acknowledgement The author wishes to acknowledge the contributions of Paula Reeves (Wildland Consultants Ltd, and later Waipa District Council), and Johlene Kelly (Department of Conservation and later Alchemists Ltd.) to Parts I and II of the Shallow Lake Management Plan. Members of the Waikato District Lakes and Freshwater Wetlands Memorandum of Agreement Group and of the Waipa Peat Lakes Accord (John Gumbley, Paula Reeves, David Klee, Tim Manukau, Jenny Charman, Giles Boundy and Ben Wolf) are also thanked for their valuable feedback on earlier versions. Several Waikato Regional Council staff (Bruno David, Mike Lake, Keri Neilson, Bruce McAuliffe, Matthew Vare, Vicki Carruthers, Bevan Jenkins, Dominique Noiton) have also provided feedback on aspects of the Shallow Lakes Management Plan and are thanked for their contributions. Page iv Doc # 2256414 Contents Acknowledgement iv Abstract ix 1 Introduction 1 1.1 Shallow lake information 2 2 Condition of shallow lakes 4 2.1 Lake water quality 4 2.1.1 Current condition 5 2.1.2 Water quality trends 6 2.2 Shallow lake health indicators 7 2.2.1 Zooplankton 9 2.2.2 Submerged aquatic plant indicators (Lake SPI) 9 2.2.3 Current condition 10 2.3 Restoration & management 12 2.3.1 Lake level setting 12 2.3.2 Riparian retirement and fencing 14 2.3.3 Enhancement of marginal habitat 16 2.3.4 Pest fish control 17 2.3.5 Reduction of nutrient and sediment inputs 19 2.3.6 Access to lakes 20 3 Waikato peat lakes 22 3.1 Hamilton city 25 3.1.1 Lake Rotokaeo (Forest Lake) 25 3.1.2 Lake Rotoroa (Hamilton Lake) 26 3.1.3 Lake Waiwhakareke (Horseshoe Lake) 29 3.2 Hauraki district 32 3.2.1 Kopuatai Burn Pools 32 3.3 Matamata- Piako district 33 3.3.1 Leesons Pond 33 3.4 South Waikato district 34 3.4.1 Lake Okoroire 34 3.5 Waikato district 36 3.5.1 Lake Areare 36 3.5.2 Lake Hotoananga 39 3.5.3 Lake Kainui (Lake D) 41 3.5.4 Lake Kaituna (Lake B) 43 3.5.5 Lake Komakorau (Lake C) 45 3.5.6 Lake Pikopiko 47 3.5.7 Lake Rotokaraka 49 Doc # 2256414 Page v 3.5.8 Lake Rotokauri 50 3.5.9 Lake Rotokawau (Black Lake) 53 3.5.10 Lake Te Kapa 56 3.5.11 Lake Tunawhakaheke (Lake E/ Tunawhakapeka/ Hurrell’s Lake) 57 3.5.12 Lake Waiwhata 60 3.5.13 Lake Whakatangi (Lake A) 61 3.6 Waipa district 63 3.6.1 Lake Cameron (Lake Kareaotahi) 63 3.6.2 Henderson’s Pond 65 3.6.3 Lake Koromatua 67 3.6.4 Lake Mangahia 69 3.6.5 Lake Mangakaware 72 3.6.6 Lake Maratoto 75 3.6.7 Lake Milicich 78 3.6.8 Lake Ngaroto 81 3.6.9 Lake Ngarotoiti 86 3.6.10 Lake Pataka 88 3.6.11 Lake Posa (Lake Pataka South) 90 3.6.12 Lake Rotomanuka (north and south) 92 3.6.13 Lake Rotongata 95 3.6.14 Rotopiko/Serpentine Lakes 97 3.6.15 Lake Rotopotaka 104 3.6.16 Lake Ruatuna 106 3.7 Waitomo district 109 3.7.1 Lake Rotokotuku (Kotukutuku) 109 4 Waikato riverine lakes 112 4.1 Hauraki district 115 4.1.1 Lake Patetonga 115 4.2 Waikato district 116 4.2.1 Lake Hakanoa 116 4.2.2 Lake Kimihia 119 4.2.3 Lake Kopuera (Rangiriri) 122 4.2.4 Lake Ohinewai 124 4.2.5 Lake Okowhao 127 4.2.6 Lake Penewaka (Penewaka Lagoon) 130 4.2.7 Lake Rotongaro 131 4.2.8 Lake Rotongaroiti 134 4.2.9 Te Otamanui Lagoon 136 4.2.10 Lake Waahi 139 Page vi Doc # 2256414 4.2.11 Lake Waikare 143 4.2.12 Lake Whangape 150 4.2.13 Lake Opuatia (Unnamed 9) 155 4.3 Waipa district 157 4.3.1 Lake Te Koutu (also Te Ko Utu) 157 5 Waikato dune lakes 160 5.1 Otorohanga district 162 5.1.1 Lake Parangi 162 5.1.2 Lake Te Rotopupu 164 5.2 Waikato district 165 5.2.1 Lake Otamatearoa 165 5.2.2 Lake Parkinson (Kohahuake) 167 5.2.3 Lake Puketi 169 5.2.4 Lake Rotoiti (Little Lake) 171 Waikato Regional Council holds no water quality information for Lake Rotoiti 171 5.2.5 Lake Un-named 3 172 5.2.6 Lake Waitamoumou 173 5.3 Waitomo district 174 5.3.1 Lake Harihari 174 5.3.2 Lake Piopio 177 5.3.3 Lake Rototapu 179 5.3.4 The Taharoa lakes – Taharoa, Numiti and Rotoroa 180 6 Waikato Karst lakes 186 6.1 Waikato District 187 6.1.1 Lake Disappear 187 6.2 Otorohanga district 188 6.2.1 Lake Koraha 188 7 Waikato volcanic lakes 190 7.1 Rotorua district 190 7.1.1 Lake Ngāhewa 191 7.1.2 Lake Tutaeinanga 193 7.2 Taupo district 195 7.2.1 Lake Rotopounamu 195 8 References 198 Doc # 2256414 Page vii Figures Figure 1 Location of lake groups within the Waikato region 1 Figure 2 The number of shallow and deep lakes within districts in the Waikato region 2 Figure 3 Estimated native vegetation cover in the catchments of shallow lakes (by type) in the Waikato region 17 Figure 4 Peat lakes in the Waikato region 22 Figure 5 Peat lake scores (including best estimates) for different aspects of the lake prioritisation method used to rank lakes in the Waikato region 24 Figure 6 Location of riverine lakes associated with the Waikato River 112 Figure 7 Riverine lake scores for different aspects of the lake prioritisation method used to score and rank the biodiversity values of lakes in the Waikato region 114 Figure 8 Dune lake scores (including best estimates) for different aspects of the lake prioritisation method used to rank lakes in the Waikato region 161 Figure 9 Volcanic and karst lake scores for different aspects of the lake prioritisation method used to rank lakes in the Waikato region for their biodiversity values 186 Page viii Doc # 2256414 Abstract This document is the second part of Waikato Regional Council’s Shallow Lake Management Plan. It has been developed as a resource statement (to accompany Volume I) that summarises available information and knowledge about the condition of shallow lakes in the Waikato region and identifies specific management recommendations for individual lakes. Volume I of the Shallow Lakes Management Plan summaries the statutory and policy framework for shallow lake management, and identifies the key management issues for shallow lakes in the Waikato region, with a specific focus on matters that WRC has responsibility for. Nine objectives and a suite of associated management strategies have been identified in Volume I to guide implementation over the next 10 years. Doc # 2256414 Page ix 1 Introduction The Waikato region contains 96 lakes greater than 1 ha in size. Seventy (71) of these are shallow lakes with a maximum depth of 10m or less. Figure 1 Location of lake groups within the Waikato region Shallow lakes are found throughout the region, having formed in conjunction with the Waikato River system, the region’s coast and cave systems, and the formerly extensive peat bogs of the region (Figure 1). Shallow lake ‘hotspots’ occur in the Waikato (peat, riverine, dune and karst lake types), Waipa (mostly peat lakes) and Waitomo Districts (mostly dune lakes) as shown in Figure 2. Doc # 2256414 Page 1 35 30 25 20 15 Shallow 10 Deep 5 0 Figure 2 The number of shallow and deep lakes within districts in the Waikato region This resource statement summarises available information about the current status of shallow lakes in the Waikato region, and identifies future management recommendations on a lake-by-lake basis. It has been prepared to accompany the Shallow Lakes Management Plan: Volume I, which identifies objectives and priorities for Waikato Regional Council’s shallow lake management programme over the next 10 years. 1.1 Shallow lake information Information for this resource statement has been sourced from a number of reports, databases and records that have been compiled by various agencies and individuals over several decades. In the 1980’s, the Waikato Valley Authority undertook several surveys of small lakes that focused on the usage, water quality and trophic status of 38 lakes within the region.