Lake Wahakari MANAGEMENT PLAN CONTENTS

Lake Wahakari MANAGEMENT PLAN CONTENTS 1. PURPOSE .....................................................................3 2. INTRODUCTION ...........................................................3 3. LAKE LOCATION MAP ..................................................5 4. LAKE OVERVIEW ..........................................................6 5. SOCIAL AND CULTURAL DIMENSION ...........................7 6. PHYSICAL CHARACTERISTICS ......................................8 7. CHEMICAL CHARACTERISTICS .....................................17 8. BIOLOGICAL CHARACTERISTICS ..................................21 9. LAND USE ....................................................................25 10. MONITORING PLAN .....................................................26 11. WORK IMPLEMENTATION PLAN ...................................28 12. BIBLIOGRAPHY ............................................................28 13. APPENDIX 1. GLOSSARY ..............................................29 2 LAKE WAHAKARI MANAGEMENT PLAN | Introduction 1. Purpose LAKE WAHAKARI MANAGEMENT PLAN The purpose of the Outstanding Northland Dune Lakes Management Plans is to implement the recommendations of the Northland Lakes Strategy Part II (NIWA 2014)1. PURPOSE by producing Lakes Management formedPlans, between starting stabilised with sand the dunes 12 along ‘Outstanding’ the west coast, represent a large proportion of warm, lowland valueThe purposelakes ,of and the Outstanding by facilitating Northland actionsDune with mana whenua iwi, landowners and other lakes in New Zealand which still have relatively good stakeholdersLakes Management in thePlans lakeis to implement catchments the to deliver priority work which will protect water water quality and high ecological values. qualityrecommendations and mitigate of the Northland current Lakes pre Strategyssures. Part II (NIWA 2014) by producing Lakes Management Plans, starting with the 12 ‘Outstanding’ value The outstanding dune lakes are grouped on the 2. Introduction lakes, and by facilitating actions with mana whenua Aupouri, including Sweetwater, Karikari and Pöuto iwi, landowners and other stakeholders in the lake Peninsulas and the Kai Iwi group North of Dargaville. Thecatchments following to deliver text priority is worktaken which directly will protect from the Northland Lakes Strategy. Northland dunewater lakesquality and and mitigate their current pressures.associated wetlandsThe lakes vary are in size, of with nationalthe majority beingand international significance. These lakes, most of whichbetween have 5 beenand 35 hectaresformed in areabetween and generally stabil less ised sand dunes2. INTRODUCTION along the west coast, represent athan large 15 metres proportion deep. Lake Taharoa of warm, of the Kailowland Iwi lakes in Group is one of the largest and deepest dune lakes in NewThe followingZealand text iswhich taken directly still from have the Northland relatively good water quality and high ecological the country, covering an area of 211.07 hectares and values.Lakes Strategy. Northland dune lakes and their being 38.81 metres deep. Lake Taharoa also has the associated wetlands are of national and international deepest recorded submerged vegetation of any lake Thesignificance. outstanding These lakes, dune most oflakes which haveare been grouped on the Aupouri, including Sweetwater, Karikari and Pōuto Peninsulas and the Kaiin the Iwi North group Island, North to 24 metres. of Dargaville. The lakes vary in size, with the majority being between 5 and 35 hectares in area and generally less than 15 metres deep. Lake Taharoa of the Kai Iwi Group is one of the 3 largest and deepest dune lakes in the country, covering an area of 211.07 hectares and being 38.81 metres deep. Lake Taharoa also has the deepest recorded submerged vegetation of any lake in the North Island, to 24 metres. The dune lakes generally have little or no continuous surface inflows or outflows, being primarily fed by rainfall directly onto their surfaces and surrounding wetlands. As a result, their levels fluctuate considerably with climatic patterns. As most of the lakes are relatively small and shallow, they have limited capacity to assimilate any contaminants. They are prone to nutrient enrichment from stock and fertiliser, 3 LAKE WAHAKARI MANAGEMENT PLAN | Introduction The dune lakes generally have little or no continuous Recreational and commercial activities on or around surface inflows or outflows, being primarily fed by some of the lakes can affect water quality, lake rainfall directly onto their surfaces and surrounding ecology and increases the risk of introduction of pest wetlands. As a result, their levels fluctuate considerably weeds and fish. with climatic patterns. As most of the lakes are relatively small and shallow, they have limited capacity The Northland Lakes Strategy (NIWA 2012) presents a to assimilate any contaminants. They are prone classification and ranking system for Northland lakes to nutrient enrichment from stock and fertiliser, including assessment of ecological values and lake particularly where lakeside vegetation has been grazed pressures and threats. The 12 highest ranked lakes or removed, and where there is direct stock access from north to south are: to the lake. Further effects on the lakes result from Outstanding (12) forestry fertilisation, sediment mobilisation during • Lakes - Wahakari, Morehurehu, Waihopo, harvest and water budget dynamics. Ngatu, Waiporohita, Waikare, Kai iwi, Taharoa, Humuhumu, Kanono, Rotokawau These lake and wetland ecosystems are important and Mokeno habitats for a wide variety of plant and animal species, some of which are regionally or nationally significant Northland Lakes Strategy (NIWA 2012, 2014) because of their rarity. These include birds such as recommends that individual lake management plans the pateke/brown teal, banded rail, New Zealand should be developed for each high value lake. This dabchick, marsh crake, fern bird and Australasian would include: bittern, the aquatic plants Hydatella inconspicua and • Descriptions of each lake and lake catchment Myriophyllum robustum and native freshwater fish • Outline of lake values and significance including the giant kokopu, banded kokopu, short (including ecological and social) jawed kokopu, inanga, dwarf inanga and dune lakes • List of agencies and individuals involved in galaxias. management The most outstanding characteristic of these lakes is • Communications plan the limited impact of invasive species on their biota, • Monitoring plan which is unparalleled elsewhere on mainland New • Identification of gaps in knowledge/research Zealand. Despite these values, the status of these lakes plan is not secure and the overall trend has been gradual • Current threats and pressures deterioration. • Management actions to mitigate or ameliorate threats and pressures Northland Regional Council monitors water quality • Work implementation plan quarterly in 26 dune lakes and undertakes ecological monitoring, along with NIWA, for ~90 dune lakes on an annual rolling basis. Annual weed surveillance Key principals of lake management are: is undertaken at high value lakes with public access. • Balance between protection and utilization Threats and pressures include biosecurity (aquatic • Managing the environmental quality of the weeds, pest fish and the risk of invasion and spread), catchment, in particular water quality eutrophication from surrounding land use for farming • Integrated management of habitat and species and forestry, occurrence of algal blooms and water (including pests) level fluctuations, especially dropping lake levels. • Monitoring as a key environmental Natural events such as summer droughts and high management tool rainfall events place further pressure on these lakes. 4 LAKE WAHAKARI MANAGEMENT PLAN | Lake Location Map The plan takes the approach of presenting robust Further south within Northland, on the west coast information on all aspects of the lakes. This includes north of Dargaville, are the three Kai Iwi Lakes (Lake Kai social and cultural, physical, chemical and biological Iwi itself, and Lakes Taharoa and Waikare, sometimes summaries of information not generally available to referred to as Waikere). the public in a condensed format. This data is the best available at the time of writing and does not represent Finally, four outstanding lakes on the Pöuto Peninsula, peer-reviewed science in the sense that errors may be on the north head of the Kaipara Harbour, round out inherent in the raw data and presence and absence the final twelves lakes of covered in the Outstanding of species changes over time. Yet it offers trends for dune lake plans. These include the west Pöuto Lake further discussion among partners involved in protection Mokeno and the east Pöuto lakes Humuhumu, Kanono and restoration activities. The plan goes on to scope and Rotokawau (Pöuto). required work for the mitigation of threats and offers a communication strategy to implement this work. Most lake names come from te reo Mäori and, therefore, some names refer to several lakes around 2.1. Geographic Lake Groupings Northland. Rotokawau is a name given to several The outstanding dune lakes within these plans all sit lakes, with one in Pöuto, two in Karikari and one in within two broad ecological districts; Aupouri and Sweetwater. Additionally, the word “kawau” means Kaipara. Within these two districts there are further the waterbird shag or cormorant and two additional geographical associations of lakes, especially relevant

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