Lake Waihopo MANAGEMENT PLAN CONTENTS

1. PURPOSE...... 3

2. INTRODUCTION...... 3

3. LAKE LOCATION MAP...... 5

4. LAKE OVERVIEW...... 6

5. SOCIAL AND CULTURAL DIMENSION...... 6

6. PHYSICAL CHARACTERISTICS...... 7

7. CHEMICAL CHARACTERISTICS...... 16

8. BIOLOGICAL CHARACTERISTICS...... 22

9. LAND USE...... 26

10. MONITORING PLAN...... 28

11. WORK IMPLEMENTATION PLAN...... 29

12. BIBLIOGRAPHY...... 29

13. APPENDIX 1. GLOSSARY...... 30

2 LAKE WAIHOPO MANAGEMENT PLAN | Introduction

1. Purpose LAKE WAIHOPO 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 1. PURPOSE formed between stabilised sand dunes along the west 2014) by producing Lakes Management Plans, starting with the 12 ‘Outstanding’ The purpose of the Outstanding Northland Dune coast, represent a large proportion of warm, lowland valueLakes lakes Management, and Plans by isfacilitating to implement the actions withlakes mana in New Zealand whenua which iwi,still have landowners relatively good and other stakeholdersrecommendations in of the the Northlandlake catchments Lakes Strategy to deliverwater quality priority and high work ecological which values. will protect water qualityPart II (NIWAand 2014)mitigate by producing current Lakes pre Managementssures. Plans, starting with the 12 ‘Outstanding’ value The outstanding dune lakes are grouped on the 2. lakes,Introduction 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 area between and generally stabil less ised sand dunes2. INTRODUCTION along the west coast, represent thana 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, Northto 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 3one of the 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,

LAKE WAIHOPO 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 WAIHOPO 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 to lakes are also called Shag Lake. To avoid confusion, biosecurity species spread. lakes sharing a name are further referred to with their sub-regional area following in parentheses. Within the Aupouri group, there are three lakes situated near Parengarenga and Houhora Harbours on the narrow LINZ topographic maps do not legally name every Aupouri Peninsula (Lakes Wahakari, Morehurehu and freshwater body. Therefore, for the purposes of the lake Waihopo). plans, additional common lake names are used which are the same as those used in the NIWA ecological At the base of the Aupouri peninsula, another cluster of surveys. These may not be the same as traditional lakes form the west coast Sweetwater group and Lake names used by iwi, which are yet to be known by the Ngatu is the only outstanding lake in this area. To the east, NRC. NRC will endeavour to consult with mana whenua on the Karikari Peninsula, Lake Waiporohita is found. iwi on their preferred traditional names for each lake.

3. LAKE LOCATION MAP

4. Lake Overview

Lake Waihopo (NRC Lake Number 78) is a shallow, 3.3 ha (3.74 m max and 1.395 mean depth) lake located on the central Aupōuri Peninsula in Far North Northland, west of Route 1 and north-west of the northern tip of Houhora Harbour. The lake is classified as a Class 1 Perched dune lake (Timms, 1982), meaning it sits above the water table.

The lake is situated in a catchment dominated by high producing grassland, closed canopy exotic pine forest and freshwater sedgeland/rushland. The NRC-defined catchment, including the lake, is 188.9 ha. The lake surface area is 3.3 ha.

The shallow water is wind-mixed and does not thermally stratify, with excess nitrogen and phosphorus stirred into the water column and available to phytoplankton. The chlorophyll-a levels mainly stay in State B but consistently rise to State C during algal blooms.

Nitrogen levels are erratic, probably entering the lake during storm events through farm/horticulture drains. Levels have declined since 2012 but the lake remains in State C. Ammonia toxicity remains in state A. Phosphorus tends to vary within state B, periodically entering State C. A major event in August 2010 saw lake phosphorus levels spike into State D. The trend is one of a slight decline in phosphorus.

Waihopo varies between the current high mesotrophic (average water quality) trophic level and low eutrophic (poor water quality). The current trend is one of slight improvement.

There is a deoxygenation phase in summer and spring in water below 1-2 m. Given the presence of black mudfish in the lake, this is a concern. pH varies around neutral (7). No water level exists for this lake. A staff gauge is due to be installed. The lake has an estimated lake residence time of 0.077 years, meaning any water entering the lake will remain for just under one month.

The lake hosts 20 native aquatic plants and three exotic non-invasive plants; water purslane, ferny azolla and bladderwort. There are no pest fish present. The lake hosts the at-risk black mudfish. Native Condition Index and Submerged Plant Index

LAKE WAIHOPO MANAGEMENT PLAN | Lake Overview

4. LAKE OVERVIEW are Thehigh lake hosts and 20 native steady, aquatic plants andowning three to native plant diversity. Invasive Impact Index is Lake Waihopo (NRC Lake Number 78) is a shallow, 3.3 exotic non-invasive plants; water purslane, ferny azolla ha (3.74 m max and 1.39 mean depth) lake locatedrelatively on and bladderwort. high There aredue no pest to fish thepresent. presence The of three exotic species. the central Aupōuri Peninsula in Far North Northland, lake hosts the at-risk black mudfish. Native Condition west of Route 1 and north-west of the northern tip Index and Submerged Plant Index are high and steady, of Houhora Harbour. The lake is classified as a ClassThe owning lake to native has plant a diversity. high Invasive level Impact Index of bird diversity and has no game species present. Of 1 Perched dune lake (Timms, 1982), meaning it sitsinterest is relatively is high the due to thesole presence record of three exotic of chestnut-breasted shelduck in this region. species. above the water table. The lake is situated in a catchment dominated by high5. TheSocial lake has a highand level ofCultural bird diversity and Dimension has no producing grassland, closed canopy exotic pine forest game species present. Of interest is the sole record of and freshwater sedgeland/rushland. The NRC-defined chestnut-breasted shelduck in this region. catchment, including the lake, is 188.9 ha. The lake 5.1. Mana whenua surface area is 3.3 ha. 5. SOCIAL AND CULTURAL DIMENSION The shallow water is wind-mixed and does not Three5.1. iwiMana/hapu whenua have rohe whenua Area of Interest in the area of Lake Waihopo; thermally stratify, with excess nitrogen and Three iwi/hapu have rohe whenua Area of Interest phosphorus stirred into the water column and Ngāinti the Kur area ofī Lake (grey), Waihopo; Ngäti Ng Kurïā (grey),i Takoto Ngäi (green) and Te Aupōuri (pink). All three iwi/hapu have available to phytoplankton. The chlorophyll-a levelsreached Takoto (green) Deed and Te Aupöuri of Settlement(pink). All three iwi/ with the Crown and the lake property has been returned. mainly stay in State B but consistently rise to State C hapu have reached Deed of Settlement with the during algal blooms. Crown and the lake property has been returned.

Nitrogen levels are erratic, probably entering the lakeRohe Rohe whenuawhenua is displayed is in thedisplayed maps below and was in the maps below and was sourced from Te Puni Kōkiriʼs during storm events through farm/horticulture drains.Te Kahuisourced from MangaiTe Puni Kökiri’s Te web Kahui Mangai pages web (www.tpk.govt.nz). Levels have declined since 2012 but the lake remains pages (www.tpk.govt.nz). in State C. Ammonia toxicity remains in state A. Phosphorus tends to vary within state B, periodically entering State C. A major event in August 2010 saw lake phosphorus levels spike into State D. The trend is one of a slight decline in phosphorus.

Waihopo varies between the current high mesotrophic (average water quality) trophic level and low eutrophic (poor water quality). The current trend is one of slight improvement.

6 5.2. Land Tenure

5.2.1. Catchment landowners and Lake bed owners

Eight landowners own 15 parcels within the lake catchment. The lake bed is owned by privately by two landowners.

5.3. Community involvement

Other than work undertaken by landowners to protect the lake, there has been no community involvement at this lake.

5.4. Public use

5.4.1. Access

Access to the lake is from Kimberley Road over private farmland.

5.4.2. Boating

5.4.2.1. Boat access

8 areare high high and and steady, steady, owning owning to to native native plant plant diversity. diversity. Invasive Invasive Impact Impact Index Index is is relativelyrelatively high high due due to to the the presence presence of of three three exotic exotic species species. .

TheThe lake lake has has a ahigh high level level of of bird bird diversity diversity and and has has no no game game species species present present. Of. Of interestinterest is isthe the sole sole record record of of chestnut chestnut-breasted-breasted shelduck shelduck in inthis this region. region.

5.5. Social Social and and Cultural Cultural Dimension Dimension

5.1.5.1. Mana Mana whenua whenua

ThreeThree iwi iwi/hapu/hapu have have rohe rohe whenua whenua Area Area of of Interest Interest in inthe the area area of of Lake Lake Waihopo; Waihopo; NgNgātiā Kurti Kurī (grey),ī (grey), Ng Ngāi āTakotoi Takoto (green) (green) and and Te Te Aup Aupōuriōuri (pink). (pink). All All three three iwi iwi/hapu/hapu have have reachedreached Deed Deed of of Settlement Settlement with with the the Crown Crown and and the the lake lake property property has has been been returned. returned.

RoheRohe whenua whenua is isdisplayed displayed in inthe the map maps belows below and and was was sourced sourced from from Te Te Puni Puni K ōKkiriōkiriʼs ʼs

TeTe Kahui Kahui Mangai Mangai web web pages pages (www.tpk.govt.nz (www.tpk.govt.nzLAKE). WAIHOPO ). MANAGEMENT PLAN | Social and Cultural Dimension

5.2.5.2. Land Land Tenure Tenure 5.2. Land Tenure 5.4.2. Boating 5.2.1 Catchment landowners and Lake 5.4.2.1. Boat access 5.2.1.5.2.1. bed ownersCatchment Catchment landowners landownersAccess and and for aLake light Lake boat isbed easy, bed but owners larger owners power boats Eight landowners own 15 parcels within the lake on trailers are more difficult due to the muddy lake catchment. The lake bed is owned by privately by bottom and thick reed beds. two landowners. EightEight landowners landowners own own 15 15 parcels parcels within within the the lake lake catchment. catchment.6. PHYSICAL The The CHARACTERISTICS lake lake bed bed is isowned owned byby privately privately by by two two landowners landowners5.3. Community. . involvement 6.1. Catchment Area with Map Other than work undertaken by landowners to The image overleaf shows the extent of the lake protect the lake, there has been no community catchment. On the left is the FENZ boundary and 5.3.5.3. Community Community involvement involvementinvolvement at this lake. a rationalised boundary prepared by NRC staff is on the right. By the end of 2018, a highly accurate 5.4. Public use LiDAR boundary will be available. The NRC-defined OtherOther than than work work undertaken undertaken5.4.1. by by landownersAccess landowners to to protect protectcatchment the the lake, area, lake, including there therethe lake hasitself, has is 188.9been been no no communitycommunity involvement involvement at at thisAccess this tolake. the lake. lake is from Kimberley Road over hectares. private farmland.

5.4.5.4. Public Public use use

5.4.1.5.4.1. Access Access

AccessAccess to to the the lake lake is isfrom from Kimberley Kimberley Road Road over over private private farmland. farmland. 7

5.4.2.5.4.2. Boating Boating

5.4.2.1.5.4.2.1. BoatBoat access access

8 8

Access for a light boat is easy, but larger power boats on trailers are more difficult due to the muddy lake bottom and thick reed beds.

6. Physical Characteristics

6.1. Catchment Area with Map

The following image shows the extent of the lake catchment. On the left is the FENZ boundary and a rationalised boundary prepared by NRC staff is on the right. By the end of 2018, a highly accurate LiDAR boundary will be available. The NRC-defined catchment area, including the lake LAKEitself WAIHOPO, is 188.9 MANAGEMENT hectares. PLAN | Physical Characteristics

The following map ((C) GNS Science 2016) of the Aupōuri Peninsula and table below it shows the geological history of the lake catchment. Waihopo has a geology comprised of weakly cemented to uncemented Early Quaternary dune, dating back 12,000 years when sea levels were higher, with loose to poorly consolidated Late Quaternary dune to the west of the catchment. 6.2. Catchment Geology and soil types 6.2. Catchment Geology and soil types The following map ((C) GNS Science 2016) of the Pōuto Peninsula and table below it shows the geological history of the lake catchment. Mokeno has a geology The following map ((C) GNS Science 2016) of the comprised of Late Quaternary dunes (lQd). These ancient dunes are now poorly Aupöuri Peninsula and table below it shows the consolidated sand. geological6.2. historyCatchment of the lake catchment. Geology Waihopo and soil types has a geology comprised of weakly cemented to uncemented Early Quaternary dune, dating back 12,000 years when sea levels were higher, with loose to poorly consolidated Late Quaternary dune to the 9 west of the catchment.

Lake Name/Plot Symbol eQd lQd (Q1d) Waihopo x x Name Early Quaternary dunes Late Quaternary dunes Description Weakly cemented and Loose to poorly uncementedLAKE WAIHOPO dune sand MANAGEMENT and consolidated PLAN | Physical sand Characteristics in mobile associated facies. Clay-rich and fixed dunes locally with sandy soil. These dunes paleosols and peat. Minor Lake Name/Plot Symbol eQd lQd (Q1d) Waihopo arose during higherx sea level sand, xmud and peat in Name 12,000Early years Quaternary ago dunes and earler.Late Quaternaryinterdune dunes lake and swamp Description Weakly cemented and Loose to poorly uncemented dune sand and consolidateddeposits. sand in mobile Geologic history Early associatedQuaternary facies. Clay-rich and fixedLate dunes Quaternary locally with sandy soil. These dunes paleosols and peat. Minor Simple name Zealandiaarose during Megasequence higher sea level sand, Zealandiamud and peat inMegasequence Terrestrial12,000 andyears agoShallow and earler. interduneTerrestrial lake and swamp and Shallow Marine Sedimentary Rocksdeposits. Marine Sedimentary Rocks Geologic history Early Quaternary Late Quaternary Simple name (Neogene)Zealandia Megasequence Zealandia(Neogene) Megasequence Absolute minimum age Terrestrial and Shallow Terrestrial and Shallow Marine Sedimentary Rocks Marine Sedimentary Rocks (millions of years before (Neogene)0.78 (Neogene) 0 present) Absolute minimum age (millions of years before 0.78 0 Absolute maximumpresent) age (millions of yearsAbsolute before maximum age 2.6 0.12 (millions of years before 2.6 0.12 present) present) Supergroup equivalentSupergroup equivalent Pakihi Pakihi Supergroup Supergroup PakihiPakihi Supergroup Supergroup stratigraphic name stratigraphic Terranename equivalent name Terrane equivalentLithology name sand sand Lithology sand sand Soil type in the catchment is portrayed in the soil map and table below. The lake is sitting within a soil type of Houhora yellow-brown sand (HO) and Tangitiki sandy Soil type in theloam catchment (TT) to the north, is portrayed west and south in andthe Pinaki soil yellowmap-brown and sandtable (PNH) below. and The lake is Soil type in the catchmentRuakaka ispeaty portrayed sandy loam in the further soil to the west.Tangitiki sandy loam (TT) to the north, west and sitting within a soil type of Houhora yellow-brown sand (HO) and Tangitiki sandy map and table below. The lake is sitting within a south and Pinaki yellow-brown sand (PNH) and loam (TT) to the north, west and south and Pinaki yellow-brown sand (PNH) and soilRuakaka type of Houhora peaty sandyellow-browny loam sand further (HO) toand the west.Ruakaka peaty sandy loam further to the west.

9 LAKE WAIHOPO MANAGEMENT PLAN | Physical Characteristics

Soil Genetic soil Geological Suite Subgroup Series Soil name Description Symbol group origin RK Organic soils Ruakaka Ruakaka Ruakaka Ruakaka peaty sand loam (RK) is found throughout Northland (except pe aty around the Kaipara where there is PZ) in what were swampy basins sand loam adjoining dunes, for example, in inter-dune swamps and the fringes of peaty sand plains. A representative profile of this low to very low fertility soil would have 150 mm of black fine sandy peaty loam, on 450 mm of black to reddish brown fine sandy peaty loam, on black loamy peat, which will contain wood fragments. There may well be ash layers where the swamp has been burnt and then peat has developed on top.

HO Yellow-brown Sands of Pinaki Moderately Houhora Hourhora Houhora series – on older west coast dunes, more mature than sands Upper to strongly sand Pinaki series, having more soil development, more organic matter and Quaternary leached stronger structure. Can have iron cementing but generally iron content dune series is a much lower than Red Hill series. [Either developed on sand from a separate source – (Central North Island rhyolitic/feldspathic sand rather than Taranaki iron sands) or the iron had settled out before this sand reached the Aupouri Peninsula.] A typical profile of Houhora sand (HO & HOH) may include: 80 to 150 mm of very dark greyish brown to olive brown loamy sand, on 80 to 150 mm of yellowish brown to pale brown sand, on brownish yellow to strong brown loamy sand.

PNH Yellow-brown Soils of Pinaki Weakly to Pinaki Pinaki Pinaki series - Pinaki sand (PN & PNH), the youngest soil in the sands Holocene moderately sand suite, is found on rolling, stabile former dunes inland of the loose sand sands and leached along the west coast. Its natural vegetation is sand grasses and scrub. sand flats A typical profile would have: 0 to 150 mm of black to very dark grey brown fine to medium sand, on 150 mm dark grey brown to very dark brown fine sand, on light olive brown to light yellowish brown medium sand. TT Podzolised Soils of Pinaki Weakly to Tangitiki Tangitiki Tangitiki series – usually rolling to steep with some very steep yellow-brown Lower moderately sandy escarpments. Is usually a mosaic of more or less podzolised soils earths Quaternary podzolised loam determined by slope and the presence or absence of kauri. Soils terraces brownish with a relatively shallow topsoil. A typical profile of Tangitiki and dunes sandy loam (TT & TTH) may include: 90 to 150 mm of very dark grey to greyish brown loamy sand, on 100 to 200 mm of pale brown to yellowish brown sandy loam to loamy sand, on 300 to 350 mm of yellowish brown to light yellowish brown sandy loam, over a 250 to 350 mm cemented brownish yellow with grey veins and mottled sandy loam. This overlies brownish yellow, strongly consolidated weathered sands.

6.3. Catchment Hydrogeology 6.5. Geomorphology - Lake type The Aupöuri sands hold an extensive groundwater and origin, area, depth, volume aquifer but, Waihopo being a Class 1 Perched dune In common with other dune lakes on the Aupöuri lake, sits above groundwater levels. Peninsula (Katavich, Yelavich and Waiparera to the south, Salt, Te Arai, Taeore, Morehurehu South 1, Te 6.4. Catchment drainage and Kahika South, Wahakari and Waipara to the north), sedimentation rates Waihopo is a Class 1 Perched dune lake formed as an The NRC-defined catchment area, including the lake elevated deflation hollow, with a sealed organic basin itself, is 188.9 hectares and produces a mean annual with humic waters. The lake has a maximum depth flow, based on hydrological models, of 453,021.8 m³/ of 3.74 m with a mean overall depth of 1.39 m. The year. The lake has an estimated lake residence time surface area of the lake is 3.3 hectares with a volume of 0.077 years, meaning any water entering the lake of 34,764.7 m³. The NRC-defined catchment area, will remain for just under one month, which is a very including the lake itself, is 188.9 hectares. high turnover in comparison to other dune lakes in the region. The average particle size of surface rock in the catchment is 1.72 on a scale of 5, a value of 1 being sand (FENZ database).

10 The following bathymetric depth map comes from a survey done by NIWA for the NRC. Waihopo’s deepest point is the single central 3.74 m basin. Waihopo has extensive shallow areas with emergent vegetation which could not be navigated by boat and therefore only 62% of the lake area was surveyed. This may have resulted LAKE WAIHOPOin an underestimate MANAGEMENT of the lake PLAN volume. | Physical Characteristics Please note that the scale of this map is in feet, not meters.

6.6. Bathymetry map The following bathymetric depth map comes from a survey done by NIWA for the NRC. Waihopo’s deepest point is the single central 3.74 m basin. Waihopo has extensive shallow areas with emergent vegetation which could not be navigated by boat and therefore only 62% of the lake area was surveyed. This may have resulted in an underestimate of the lake volume. Please note that the scale of this map is in feet, not meters.

6.7. Natural inlets and outlets 6.7. Natural inlets and outlets

There are no natural inlets and there is only one outlet There are no natural inlets and there is only one outlet to Waihopo Stream to the east, through wetland to Houhora Harbour. However, farm/horticulture drains enter to Waihopo Stream to the east, through wetland to the lake in direct point-discharges. 6.8. Wetland associations Houhora Harbour. However, farm/horticulture drains Waihopo is surrounded by a “Top 150” wetland. enter the lake in direct point-discharges.

6.8. Wetland associations Waihopo is surrounded by a “Top 150” wetland.

13 6.9. Connectivity

The lake is not connected to any other waterbody other than through its one outlet through6.9. wetlandConnectivity to the east.

6.9.The lake isConnectivity not connected to any other waterbody other than through6.10. its one Airoutlet Temperature through6.10. wetland to theAir east temperature. The lake is not connected to any other waterbody Temperature recordings of Kaitaia air temperature are 6.10. Air temperature other than through its one outlet through wetland to used as a proxy. TemperatureTemperature recordings recordings of Kaitaia air oftemperature Kaitaia are air used temperature as a proxy. are used as a proxy. the east. Kaitaia Observatory Mean Monthly Temperature deg C Kaitaia Observatory Mean Monthly Temperature deg C 25 20 15 25 10 5 20 0 15 10 Jan 2006 Jan 2007 Jan 2008 Jan 2009 Jan 2010 Jan 2011 Jan 2012 Jan 2013 Jan 2014 Jan 2015 Jan 2016 Sep 2006 2006 Sep 2007 Sep 2008 Sep 2009 Sep 2011 Sep 2013 Sep 2015 Sep 2016 Sep Sep 2010 2010 Sep 2012 Sep 2014 Sep May 2006 May 2007 May 2008 May 2009 May 2011 May 2013 May 2015 May 2016 5 May 2010 May 2012 May 2014

0 6.11. Thermal stratification

The graphs below show temperature at depth throughout the water column, by

season. EachJan 2006 colouredJan 2007 line representsJan 2008 oneJan 2009 sample. WaterJan 2010 temperaturesJan 2011 throughoutJan 2012 Jan 2013 Jan 2014 Jan 2015 Jan 2016 Sep 2006 2006 Sep 2007 Sep 2008 Sep 2009 Sep 2011 Sep 2013 Sep 2015 Sep 2016 Sep Sep 2010 2010 Sep 2012 Sep 2014 Sep May 2006 May 2007 May 2008 May 2009 May 2011 May 2013 May 2015 May 2016 the year range from 12.98 degrees C to 26.88 degrees C.May 2010 May 2012 May 2014

The lake, being very shallow, does not thermally stratify and temperature is fairly uniform at all depths year round. 6.11. Thermal stratification Due to lack of stratification, nutrients are available throughout the water column 11 throughout the year due to wind mixing. The graphs below show temperature at depth throughout the water column, by season. Each coloured line represents one sample. Water temperatures throughout the year range from 12.98 degrees C to 26.88 degrees C. 14

The lake, being very shallow, does not thermally stratify and temperature is fairly uniform at all depths year round.

Due to lack of stratification, nutrients are available throughout the water column throughout the year due to wind mixing.

LAKE WAIHOPO MANAGEMENT PLAN | Physical Characteristics

6.11. Thermal stratification The lake, being very shallow, does not thermally The graphs below show temperature at depth stratify and temperature is fairly uniform at all depths throughout the water column, by season. Each year round. coloured line represents one sample. Water temperatures throughout the year range from 12.98 Due to lack of stratification, nutrients are available degrees C to 26.88 degrees C. throughout the water column throughout the year due to wind mixing.

Waihopo Summer Temperature Depth Proﬁles

28 26 24 22 20 18 Temp C Temp Temp C Temp 16 14 12 10 0.5 1 1.5 1 2 2.5 1.5 3 3.5 2 4 2.5 3 3.5 4 Depth m

06/12/05 30/01/08 08/02/11

21/02/12 19/02/13 12/02/14

Waihopo Autumn Temperature Depth Proﬁles

28 26 24 22 20 18 Temp C Temp Temp C Temp 16 14 12 10 0.5 1 1.5 1 2 2.5 1.5 3 3.5 2 4 2.5 3 3.5 4 Depth m

14/03/06 25/05/06 08/05/07 11/03/09

26/05/09 24/05/11 15/05/12 14/05/13

Waihopo Winter Temperature Depth Proﬁles

28 26 24 22 20 18 Temp C Temp Temp C Temp 16 14 14 12 12 10 0.5 1 1.5 2 2.5 3 3.5 4 Depth m

09/08/06 07/08/07 01/07/08 18/08/09

17/08/10 01/08/11 07/08/12 14/08/13

Waihopo Summer Temperature Depth Proﬁles

28 26 24 22 20 18 Temp C Temp 16 14 12 10 0.5 1 1.5 2 2.5 3 3.5 4 Depth m

06/12/05 30/01/08 08/02/11

21/02/12 19/02/13 12/02/14

Waihopo Autumn Temperature Depth Proﬁles

28 26 24 22 20 18 Temp C Temp 16 14 12 10 0.5 1 1.5 2 2.5 3 3.5 4 Depth m

LAKE WAIHOPO MANAGEMENT PLAN | Physical Characteristics 14/03/06 25/05/06 08/05/07 11/03/09

26/05/09 24/05/11 15/05/12 14/05/13

Waihopo Winter Temperature Depth Proﬁles

28 26 24 22 20 18 Temp C Temp 16 14 12 10 0.5 1 1.5 2 2.5 3 3.5 4 Depth m

09/08/06 07/08/07 01/07/08 18/08/09

17/08/10 01/08/11 07/08/12 14/08/13

Waihopo Spring Temperature Depth Proﬁles

28 26 24 22 20 18 Temp C Temp 16 14 12 10 0.5 1 1.5 2 2.5 3 3.5 4 Depth m

03/11/04 30/10/06 07/11/07 09/09/08

17/11/08 16/11/10 23/11/11 07/11/12

6.12. Rainfall and drought

The graph below shows cumulative rainfall by year displayed as seasons within each bar. Note that summer includes December from the year prior along with January and February of the year shown on the X axis. 2006 summer data is not available. Greyed season indicates that a one month of the three months for that season, has no data available so this portion of the bar in underestimated.

Waiharaha mean annual rainfall by season 13

1600 1400 1200 1000 800 mm 600 400 200 0 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

summer autumn winter spring

6.13. Lake level

No water level exists for this lake. A staff gauge is due to be installed.

6.14. Sunshine

Kaitaia sunshine recordings are used as a proxy.

Waihopo Spring Temperature Depth Proﬁles

28 26 24 22 20 18 Temp C Temp 16 14 12 10 0.5 1 1.5 2 2.5 3 3.5 4 Depth m

03/11/04 30/10/06 07/11/07 09/09/08

17/11/08 16/11/10 23/11/11 07/11/12

6.12. Rainfall and droughtLAKE WAIHOPO MANAGEMENT PLAN | Physical Characteristics

6.12. TheRainfall graph and below drought shows cumulative rainfallX axis. 2006 by yearsummer displayed data is not asavailable. seasons Greyed within each bar. Note that summer includes December from the year prior along with January The graph below shows cumulative rainfall by year season indicates that a one month of the three and February of the year shown on the X axis. 2006 summer data is not available. displayed as seasons within each bar. Note that months for that season, has no data available so this Greyed season indicates that a one month of the three months for that season, has portion of the bar in underestimated. summer noincludes data December available from so the this year portion prior along of the bar in underestimated. with January and February of the year shown on the Waiharaha mean annual rainfall by season

1600 1400 1200 1000 800 mm 600 400 200 0 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

summer autumn winter spring

6.13. Lake level 6.14. Sunshine NoKaitaia water level6.13. exists Observatory for thisLake lake. levelA staff monthly gauge is due total Kaitaia sunshine sunshineSUMMER hours recordings AUTUMN are used WINTER as a SPRING proxy. to be installed. 300 No water level exists for this lake. A staff6.15. gauge Wind is speeddue to be installed. 250 200 Kaitaia wind speed recordings are used as a proxy. 150 6.14. Sunshine 100 50 Kaitaia Observatory monthly total sunshine SUMMER hours AUTUMN WINTER SPRING 0 Kaitaia sunshine recordings are used as a proxy. 300 250 200 Jan 2006 Jan 2007 Jan 2008 Jan 2009 Jan 2011 Jan 2013 Jan 2015 Jan 2016 Jan 2010 Jan 2012 Jan 2014 Sep 2006 2006 Sep 2007 Sep 2008 Sep 2009 Sep 2011 Sep 2013 Sep 2015 Sep 2016 Sep Sep 2010 2010 Sep 2012 Sep 2014 Sep May 2006 May 2007 May 2008 May 2009 May 2011 May 2013 May 2015 May 2016 150 May 2010 May 2012 May 2014 100 50 0 6.15. Wind speed 16

Kaitaia wind speed recordings are used as a proxy. Jan 2006 Jan 2007 Jan 2008 Jan 2009 Jan 2011 Jan 2013 Jan 2015 Jan 2016 Jan 2010 Jan 2012 Jan 2014 Sep 2006 2006 Sep 2007 Sep 2008 Sep 2009 Sep 2011 Sep 2013 Sep 2015 Sep 2016 Sep Sep 2010 2010 Sep 2012 Sep 2014 Sep May 2006 May 2007 May 2008 May 2009 May 2011 May 2013 May 2015 May 2016 May 2010 May 2012 May 2014

Kaitaia 6.15. Wind Ews speed monthly mean wind speed (m/s) SUMMER AUTUMN WINTER SPRING

6 Kaitaia5 wind speed recordings are used as a proxy. 4 3 2 1 Kaitaia Ews monthly mean wind speed (m/s) SUMMER AUTUMN WINTER SPRING 0 6 5 4 Jan 2006 Jan 2007 Jan 2008 Jan 2009 Jan 2011 Jan 2013 Jan 2015 Jan 2016 Jan 2010 Jan 2012 Jan 2014 Sep 2006 2006 Sep 2007 Sep 2008 Sep 2009 Sep 2011 Sep 2013 Sep 2015 Sep 2016 Sep Sep 2010 2010 Sep 2012 Sep 2014 Sep May 2006 May 2007 May 2008 May 2009 May 2011 May 2013 May 2015 May 2016 3 May 2010 May 2012 May 2014 2 1 0 6.16. Light incidence (Secchi, Total Suspended Solids, Chlorophyll-a) 14

Three measures which are indicators of water clarity include chlorophyll-a (presence Jan 2006 Jan 2007 Jan 2008 Jan 2009 Jan 2011 Jan 2013 Jan 2015 Jan 2016 Jan 2010 Jan 2012 Jan 2014 Sep 2006 2006 Sep 2007 Sep 2008 Sep 2009 Sep 2011 Sep 2013 Sep 2015 Sep 2016 Sep Sep 2010 2010 Sep 2012 Sep 2014 Sep May 2006 May 2007 May 2008 May 2009 May 2011 May 2013 May 2015 May 2016 of micro-algal growth in the water column,May 2010 total suspendedMay 2012 solidsMay 2014 and the direct measure of visibility at depth by lowering a black and white Secchi disk until it is no longer6.16. visible. Light As seen incidence from the(Secchi, graph Total below, Suspended Waihopo experiencesSolids, Chlorophyll regular-a) a lgal blooms (green line). Visibility, based on Secchi depth, is poor as a result. Three measures which are indicators of water clarity include chlorophyll-a (presence ofThe micro table-algal below growth the graph in the shows water thecolumn, National total Policy suspended Statement solids for and Freshwater the direct measureManagement of visibility states atfor depth phytoplankton by lowering (chlorophyll a black and-a). whiteConsistent Secchi algal disk blooms until it is into no longerState C visible., from aAs mainstay seen from in Statethe graph B, have below, marked Waihopo the lake’s experiences history. regular algal blooms (green line). Visibility, based on Secchi depth, is poor as a result.

The table below the graph shows the National Policy Statement for Freshwater Management states for phytoplankton (chlorophyll-a). Consistent algal blooms into State C, from a mainstay in State B, have marked the lake’s history.

LAKE WAIHOPO MANAGEMENT PLAN | Physical Characteristics

6.16. Light incidence (Secchi, Total regular algal blooms (green line). Visibility, based on Suspended Solids, Chlorophyll-a) Secchi depth, is poor as a result. Three measures which are indicators of water clarity include chlorophyll-a (presence of micro-algal growth The table below the graph shows the National Policy in the water column, total suspended solids and the Statement for Freshwater Management states for direct measure of visibility at depth by lowering a black phytoplankton (chlorophyll-a). Consistent algal blooms and white Secchi disk until it is no longer visible. As into State C, from a mainstay in State B, have marked seen from the graph below, Waihopo experiences the lake’s history.

14 Lake Waihopo Water Clarity (NPS State colours apply to green line only) 12 Total Suspended Solids g/m3 10 Secchi Depth m Chlorophyll a (low level) mg/m3 8

0 4/6/2006 8/6/2006 4/6/2007 8/6/2007 4/6/2008 8/6/2008 4/6/2009 8/6/2009 4/6/2010 8/6/2010 4/6/2011 8/6/2011 4/6/2012 8/6/2012 4/6/2013 8/6/2013 4/6/2014 8/6/2014 4/6/2015 8/6/2015 4/6/2016 12/6/2005 12/6/2006 12/6/2007 12/6/2008 12/6/2009 12/6/2010 12/6/2011 12/6/2012 12/6/2013 12/6/2014 12/6/2015

Attribute Unit Lake Type State Annual Median Annual Maximum Narrative State Lake ecological communities are healthy and resilient, similar to natural Phytoplankton mg Chlorophyll-‐a/m³ All A ≤2 ≤10 reference conditions. Lake ecological communities are slightly impacted by additional algal and/or Phytoplankton mg Chlorophyll-‐a/m³ All B >2 and ≤5 >10 and ≤25 plant growth arising from nutrients levels that are elevated above natural reference conditions. Attribute Unit Lake Type State Annual Median Annual Maximum NarrativeLake State ecological communities are moderately impacted by additional algal and Lakeplant ecological growth communities arising are healthy from and nutrients resilient, levels similar to natural that are elevated well above natural PhytoplanktonPhytoplankton mg mg Chlorophyll-a/m Chlorophyll-‐a/m³³ AllAll AC >5 ≤2 and ≤12 >25 ≤10 and ≤60 referencereference conditions. conditions. Reduced water clarity is likely to affect habitat available Lakefor ecological native communities macrophytes. are slightly impacted by additional algal and/or Phytoplankton mg Chlorophyll-a/m³ All B >2 and ≤5 >10 and ≤25 plantLake growth ecological arising from nutrients communities levels that are are elevated moderately above natural impacted by additional algal and National referenceplant conditions. growth arising from nutrients levels that are elevated well above natural Phytoplankton mg Chlorophyll-‐a/m³ All 12 60 Bottom Line Lakereference ecological communities conditions. are Reduced moderately water impacted clarity by additional is likely algal and to affect habitat available plant growth arising from nutrients levels that are elevated well above natural Phytoplankton mg Chlorophyll-a/m³ All C >5 and ≤12 >25 and ≤60 for native macrophytes. referenceLake conditions. ecological Reduced communities water clarity have is likely to undergone affect habitat or available are at high risk of a regime for shift native macrophytes. to a persistent, degraded state (without native macrophyte/seagrass Phytoplankton mg Chlorophyll-‐a/m³ All D >12 >60 Lakecover), ecological due communities to impacts are moderately of elevated impacted by nutrients additional algal leading and to excessive algal and/or National plant growth arising from nutrients levels that are elevated well above natural Phytoplankton mg Chlorophyll-a/m³ All 12 60 plant growth, as well as from losing oxygen in bottom waters of deep lakes. Bottom Line reference conditions. Reduced water clarity is likely to affect habitat available for native macrophytes. Lake ecological communities have undergone or are at high risk of a regime shift to a persistent, degraded state (without native macrophyte/seagrass 7.Phytoplankton Chemicalmg Chlorophyll-a/m Characteristics³ All D >12 >60 cover), due to impacts of elevated nutrients leading to excessive algal and/or plant growth, as well as from losing oxygen in bottom waters of deep lakes. 7.1. Water Quality

7.1.1. Nutrients

7.1.1.1. Limiting nutrient assay

Max Gibbs (pers. comm.) from NIWA conducted limiting nutrient assays on several lakes, including Waihopo. Significant results are highlighted. For the years and 15 seasons assayed, nitrogen plus phosphorus is the limiting nutrient combination in summer. Lack of these nutrients regulate the ability of plants to grow optimally.

Autumn 2014 Summer 2015 Autumn 2014 Summer 2015 Autumn 2014 Summer 2015 Lake Initial Chla Initial Chla Change in Change in Proportional change over control Proportional change over control ( mg m-3) ( mg m-3) Control Control +N +P +N+P NP-‐P +N +P +N+P Waihopo 2.45 3.5 1.20 1.13 1.10 1.09 1.07 -‐0.02 0.97 1.03 1.10

7.1.1.2. Ammoniacal Nitrogen (Toxicity)

Ammoniacal nitrogen (NH4-N), also often called ‘ammonium’, covers two forms of nitrogen; ammonia (NH3) and ammonium (NH4). It enters waterways primarily through point source discharges, such as raw sewage or livestock effluent. It is toxic to aquatic life at high concentrations.

14 Lake Waihopo Water Clarity (NPS State colours apply to green line only) 12 Total Suspended Solids g/m3 10 Secchi Depth m Chlorophyll a (low level) mg/m3 8

Attribute Unit Lake Type State Annual Median Annual Maximum Narrative State Lake ecological communities are healthy and resilient, similar to natural Phytoplankton mg Chlorophyll-‐a/m³ All A ≤2 ≤10 reference conditions. Lake ecological communities are slightly impacted by additional algal and/or Phytoplankton mg Chlorophyll-‐a/m³ All B >2 and ≤5 >10 and ≤25 plant growth arising from nutrients levels that are elevated above natural reference conditions. Lake ecological communities are moderately impacted by additional algal and plant growth arising from nutrients levels that are elevated well above natural Phytoplankton mg Chlorophyll-‐a/m³ All C >5 and ≤12 >25 and ≤60 reference conditions. Reduced water clarity is likely to affect habitat available for native macrophytes. Lake ecological communities are moderately impacted by additional algal and National plant growth arising from nutrients levels that are elevated well above natural Phytoplankton mg Chlorophyll-‐a/m³ All 12 60 Bottom Line reference conditions. Reduced water clarity is likely to affect habitat available for native macrophytes. Lake ecological communities have undergone or are at high risk of a regime LAKE WAIHOPO shift MANAGEMENT to a persistent, PLAN degraded | Chemical state (without Characteristics native macrophyte/seagrass Phytoplankton mg Chlorophyll-‐a/m³ All D >12 >60 cover), due to impacts of elevated nutrients leading to excessive algal and/or plant growth, as well as from losing oxygen in bottom waters of deep lakes. 7.1.1.2. Ammoniacal Nitrogen (Toxicity) 7. CHEMICAL CHARACTERISTICS 7.7.1. Chemical Water Characteristics Quality Ammoniacal nitrogen (NH4-N), also often called ‘ammonium’, covers two forms of nitrogen; ammonia 7.1.1.7.1. NutrientsWater Quality (NH3) and ammonium (NH4). It enters waterways primarily through point source discharges, such as raw 7.1.1.1. Limiting nutrient assay 7.1.1. Nutrients sewage or livestock effluent. It is toxic to aquatic life at Max Gibbs (pers. comm.) from NIWA conducted high concentrations. limiting nutrient7.1.1.1. assays on severalLimiting lakes, nutrient including assay Waihopo. Significant results are highlighted. For the Maxyears andGibbs seasons (pers. assayed, comm.) nitrogen from plus NIWA phosphorus conducted The table limiting following nutrient the graph assays shows on the several National lakesis the limiting, including nutrient Waihopo combination. Significant in summer. Lackresults arePolicy highlighted. Statement Freshwater For the Management years and limits for seasonsof these nutrients assayed, regulate nitrogen the ability plus of plants phosphorus to grow lakeis the state. limiting Waihopo nutrient has remained combination in State A orin low summer.optimally. Lack of these nutrients regulate theammonia ability of toxicity plants levels. to grow optimally.

7.1.1.2. Ammoniacal Nitrogen (Toxicity)

Attribute Unit Lake Type State Annual Median Annual Maximum Narrative State Ammonia mg NH4-N/L (mg ammoniacal- 99% species protection level: No observed effect on any All A ≤0.03 ≤0.05 (Toxicity) nitrogen per litre) species tested Ammonia mg NH4-N/L (mg ammoniacal- 95% species protection level: Starts impacting occasionally All B >0.03 and ≤0.24 >0.05 and ≤0.40 (Toxicity) nitrogen per litre) on the 5% most sensitive species 80% species protection level: Starts impacting regularly on Ammonia mg NH4-N/L (mg ammoniacal- All C >0.24 and ≤1.30 >0.40 and ≤2.20 the 20% most sensitive species (reduced survival of most (Toxicity) nitrogen per litre) sensitive species) 80% species protection level: Starts impacting regularly on Ammonia mg NH4-N/L (mg ammoniacal- National All 1.3 2.2 the 20% most sensitive species (reduced survival of most (Toxicity) nitrogen per litre) Bottom Line sensitive species) Ammonia mg NH4-N/L (mg ammoniacal- Starts approaching acute impact level (ie risk of death) for All D >1.30 >2.20 (Toxicity) nitrogen per litre) sensitive species

16 LAKE WAIHOPO MANAGEMENT PLAN | Chemical Characteristics

7.1.1.3. Nitrogen The table following the chart shows the National Policy Total nitrogen levels are erratic, most likely entering Statement for Freshwater Management limits for lake the lake during storm events through farm/ state. There is a decreasing trend in nitrogen, yet the horticultural drains. Overall, nitrogen levels have lake has yet to leave State C. declined gradually since 2012.

Attribute Unit Lake Type State Annual Median Narrative State Total Nitrogen Lake ecological communities are healthy and resilient, similar to natural reference g/m3 Polymictic A ≤.3 (Trophic state) conditions. Lake ecological communities are slightly impacted by additional algal and/or plant Total Nitrogen g/m3 Polymictic B >.3 and ≤.5 growth arising from nutrients levels that are elevated above natural reference (Trophic state) conditions. Lake ecological communities are moderately impacted by additional algal and plant Total Nitrogen g/m3 Polymictic C >.5 and ≤.8 growth arising from nutrients levels that are elevated well above natural reference (Trophic state) conditions. Lake ecological communities are moderately impacted by additional algal and plant Total Nitrogen National g/m3 Polymictic 0.8 growth arising from nutrients levels that are elevated well above natural reference (Trophic state) Bottom Line conditions Lake ecological communities have undergone or are at high risk of a regime shift to a persistent, degraded state (without native macrophyte/seagrass cover), due to impacts Total Nitrogen g/m3 Polymictic D >.8 of elevated nutrients leading to excessive algal and/or plant growth, as well as from (Trophic state) losing oxygen in bottom waters of deep lakes.

7.1.1.4. Phosphorus state. The lake tends to vary within State B, periodically Total phosphorus is relatively low, other than periodic entering State C. A major event in August 2010 saw spikes, most notably in August 2010. lake phosphorus push into State D. Then trend is one of slight decline in phosphorus. The table following the chart shows the National Policy Statement for Freshwater Management limits for lake

17 LAKE WAIHOPO MANAGEMENT PLAN| Chemical Characteristics

Lake Waihopo Total Phosphorus (TP) g/m3-‐P

0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 1/12/2005 1/05/2006 1/10/2006 1/03/2007 1/08/2007 1/01/2008 1/06/2008 1/11/2008 1/04/2009 1/09/2009 1/02/2010 1/07/2010 1/12/2010 1/05/2011 1/10/2011 1/03/2012 1/08/2012 1/01/2013 1/06/2013 1/11/2013 1/04/2014 1/09/2014 1/02/2015 1/07/2015 1/12/2015 1/05/2016

Attribute Unit Lake Type State Annual Median Narrative State Total Phosphorus Lake ecological communities are healthy and resilient, similar to Attribute g/m3Unit LakeAll Type StateA Annual≤ Median .01 Narrative State (Trophic state) natural reference conditions. Total Phosphorus Lake ecological communities are healthy and resilient, similar to g/m3 All A ≤ .01 Lake ecological communities are slightly impacted by additional algal Total (Trophic Phosphorus state) natural reference conditions. g/m3 All B > .01 and ≤ .20 and plant growth arising from nutrients levels that are elevated above (Trophic state) Lake ecological communities are slightly impacted by additional algal Total Phosphorus natural reference conditions. g/m3 All B > .01 and ≤ .20 and plant growth arising from nutrients levels that are elevated above (Trophic state) Lake ecological communities are moderately impacted by additional Total Phosphorus natural reference conditions. g/m3 All C > .02 and ≤ .05 algal and plant growth arising from nutrients levels that are elevated (Trophic state) Lake ecological communities are moderately impacted by additional Total Phosphorus well above natural reference conditions. g/m3 All C > .02 and ≤ .05 algal and plant growth arising from nutrients levels that are elevated (Trophic state) Lake ecological communities are moderately impacted by additional Total Phosphorus National well above natural reference conditions. g/m3 All 0.05 algal and plant growth arising from nutrients levels that are elevated (Trophic state) Bottom Line Lake ecological communities are moderately impacted by additional Total Phosphorus National well above natural reference conditions. g/m3 All 0.05 algal and plant growth arising from nutrients levels that are elevated (Trophic state) Bottom Line Lake ecological communities have undergone or are at high risk of a well above natural reference conditions. regime shift to a persistent, degraded state (without native Total Phosphorus Lake ecological communities have undergone or are at high risk of a g/m3 All D > .05 regimemacrophyte/seagrass shift to a persistent, cover), degraded due state to (without impacts native of elevated nutrients (Trophic Total Phosphorus state) g/m3 All D > .05 macrophyte/seagrassleading to excessive cover), due algal to impacts and/or of elevated plant nutrients growth, as well as from losing (Trophic state) leadingoxygen to in excessive bottom algal and/or waters plant of growth, deep lakes. as well as from losing oxygen in bottom waters of deep lakes. Trophic Level Index

The trophic level index (TLI) is used in New Zealand as a measure of the nutrient status of lakes. The index combines four variables; phosphorus, nitrogen, visual clarity7.1.1.5. (SecchiTrophic Level disk Index depth) and algal biomassshows, each an overlyweighted nutrient-rich equally. lake prone to algal The trophic level index (TLI) is used in New Zealand as blooms and poor light incidence, this shading affecting A low TLI score indicates a healthy lake with clear water and little algal bloom a measure of the nutrient status of lakes. The index the health of submerged native plant communities. occurrence. A high TLI shows an overly nutrient-rich lake prone to algal blooms and combines four variables; phosphorus, nitrogen, visual The TLI trend for Waihopo varies between the current poor light incidence, this shading affecting the health of submerged native plant communitiesclarity (Secchi disk. depth) and algal biomass, each high mesotrophic (average water quality) and low weighted equally. eutrophic (poor water quality). Currently, the trend is The TLI trend for Waihopo varies between theone currentof slight improvement. high mesotrophic (average waterA low TLI quality) score indicates and low a healthy eutrophic lake with (poor clear water quality). Currently, the trend is one of slightwater and improvement. little algal bloom occurrence. A high TLI

LAKE WAIHOPO MANAGEMENT PLAN | Chemical Characteristics

Lake Waihopo Trophic Level Index Score

Water Trophic TLI 5 Quality Level Score Very Good Microtrophic <2

4 Good Oligotrophic 2-3 Average Mesotrophic 3-4

3 Poor Eutrophic 4-5 Very Poor Supertrophic >5 No Data No data 2 available 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

Water TLI Trophic Level Quality Score The graph below is a display of TLI scores. This allows nitrogen is the consistently main contributor to the TLI Very Good Microtrophic <2 Goodinterpretation ofOligotrophic the four contributing 2-‐3 variables which score followed by Secchi disk (water clarity). Averageare combined intoMesotrophic an overall TLI score.3-‐4 From this chart, Poor Eutrophic 4-‐5 Very Poor Supertrophic >5 No data No Data available

The graph below is a display of TLI scores. This allows interpretation of the four contributing variables which are combined into an overall TLI score. From this chart, nitrogen is the consistently main contributor to the TLI score followed by Secchi disk (water clarity).

7.1.2. Dissolved Oxygen g/m³

Although the lake does not thermally stratify due to its shallow nature, there is a 19 deoxygenation phase in summer and spring in water deeper than 1-2 m. Given the presence of black mudfish in the lake, which are unlikely to tolerate deoxygenated conditions, this is a concern.

The table below shows the dissolved oxygen (at 15 degrees C) limits for New Zealand freshwater fish from https://www.niwa.co.nz/freshwater-and- estuaries/research-projects/dissolved-oxygen-criteria-for-fish. These guidelines help interpret the depth profiles as to the depth of the water column usable by fish species during the different seasons displayed in the graphs.

LAKE WAIHOPO MANAGEMENT PLAN | Chemical Characteristics

7.1.2. Dissolved Oxygen g/m³ The table below shows the dissolved oxygen (at 15 Although the lake does not thermally stratify due to degrees C) limits for New Zealand freshwater fish its shallow nature, there is a deoxygenation phase in from https://www.niwa.co.nz/freshwater-and- summer and spring in water deeper than 1-2 m. Given estuaries/research-projects/dissolved-oxygen- the presence of black mudfish in the lake, which are criteria-for-fish. These guidelines help interpret the unlikely to tolerate deoxygenated conditions, this is a depth profiles as to the depth of the water column concern. usable by fish species during the different seasons displayed in the graphs.

Waihopo Summer DO Depth Proﬁles 10 Waihopo Summer DO Depth Proﬁles 8 6 10 DO 4 8 2 6

0 DO 4 0.5 1 1.5 2 2.5 3 3.5 4 2 Depth m 0 0.5 1 1.5 2 2.5 3 3.5 4 06/12/05 30/01/08 Depth 08/02/11 m 21/02/12 19/02/13 12/02/14

06/12/05 30/01/08 08/02/11 21/02/12 19/02/13 12/02/14 Waihopo Autumn DO Depth Proﬁles 10 8 Waihopo Autumn DO Depth Proﬁles 6

DO 4 10 2 8 20 0 6

DO 0.5 1 1.5 2 2.5 3 3.5 4 4 Depth m 2 0 14/03/06 25/05/06 08/05/07 11/03/09 26/05/09 0.5 1 1.5 2 2.5 3 3.5 4 18/05/10 24/05/11 15/05/12 14/05/13 Depth m

24 14/03/06 25/05/06 08/05/07 11/03/09 26/05/09

18/05/10 24/05/11 15/05/12 14/05/13

Waihopo Summer DO Depth Proﬁles

10 8 6

DO 4 2 0 0.5 1 1.5 2 2.5 3 3.5 4 Depth m

06/12/05 30/01/08 08/02/11

21/02/12 19/02/13 12/02/14 LAKE WAIHOPO MANAGEMENT PLAN | Chemical Characteristics

Waihopo Autumn DO Depth Proﬁles

10 8 6

DO 4 2 0 0.5 1 1.5 2 2.5 3 3.5 4 Depth m

14/03/06 25/05/06 08/05/07 11/03/09 26/05/09

18/05/10 24/05/11 15/05/12 14/05/13

Waihopo Winter DO Depth Proﬁles Waihopo Winter DO Depth Proﬁles 24 10 10 8 8 6

DO 6 4 DO 4 2 2 0 0 0.5 1 1.5 2 2.5 3 3.5 4 0.5 1 Depth 1.5 m 2 2.5 3 3.5 4 Depth m 09/08/06 07/08/07 01/07/08 18/08/09 09/08/06 07/08/07 01/07/08 18/08/09 17/08/10 01/08/11 07/08/12 14/08/13 17/08/10 01/08/11 07/08/12 14/08/13

Waihopo Spring DO Depth Proﬁles Waihopo Spring DO Depth Proﬁles 10 10 8 8 6

DO 6 4 DO 4 2 2 0 0 0.5 1 1.5 2 2.5 3 3.5 4 0.5 1 1.5 2 2.5 3 3.5 4 Depth m Depth m

03/11/04 30/10/06 07/11/07 09/09/08 03/11/04 30/10/06 07/11/07 09/09/08 17/11/08 16/11/10 23/11/11 07/11/12 17/11/08 16/11/10 23/11/11 07/11/12

7.1.3. pH 21 7.1.3. pH The pH levels in Waihopo vary around 7 (neutral). The pH levels in Waihopo vary around 7 (neutral).

25 25

LAKE WAIHOPO MANAGEMENT PLAN | Biological Characteristics

7.1.3. pH The pH levels in Waihopo vary around 7 (neutral).

8. BIOLOGICAL CHARACTERISTICS The table presents plant communities in nearby dune 8.1. Lake Biodiversity and Biosecurity lakes as a comparison and indication of biosecurity species species of concern which should be contained wherever possible. Data is derived from annual NIWA 8.1.1. Plants ecological surveys. Waihopo hosts 20 native aquatic plants and three exotic non-invasive plants; water purslane, ferny Two rare ferns, Cyclosorus interruptus and marsh azolla and bladderwort (Utricularia gibba), all fern (Thelypteris confluens) grow on the swampy lake displayed in the table below. margins. The native bladderwort, Utricularia australis which is ranked as Nationally Critical, the highest The table is organised as a depth gradient, from threat category, was common in Lake Waihopo but emergent plants to those which are submerged, for has not been seen since 2004. This is most likely due each of the invasives and natives. Rare natives are to a decline in water quality. presented last. Waihopo contains one rare native, the bladderwort (Utricularia australis).

22 LAKE WAIHOPO MANAGEMENT PLAN | Biological Characteristics

Depth and Plant Type Zone Biogeography Common Name Species Waitahora lagoon Waitahora Lakes Te Werahi Lagoon Ngakeketa North/Te Paki Ngakeketa South Te Paki Dune Lake Austria Pretty Waipara/Dead Kihona Wahakari Te Kahika Te Kahika South Morehurehu 1 Morehurehu South 2 Morehurehu South (driedTaeore out) Te Arai Lake Wetland Ephemeral Arai Te Bulrush Salt Waihopo Yelavich Katavich Waiparera Frequency Erect emergent Invasive exotic royal fern Osmunda regalis x 1 Erect emergent Non-‐invasive exotic bulbous rush Juncus bulbosus x 1 Sprawling emergent Invasive exotic alligator weed Alternanthera philoxeroides x x 2 Sprawling emergent Invasive exotic gypsywort Lycopus europaeus x 1 Sprawling emergent Invasive exotic mercer grass, paspalum Paspalum distichum x 1 Sprawling emergent Non-‐invasive exotic water purslane Ludwigia palustris x x x x x x x x 8 Low growing turf Non-‐invasive exotic water starwort Callitriche stagnalis x 1 Floating leaved Non-‐invasive exotic swamp lily Ottelia ovalifolia x x 2 Free floating Non-‐invasive exotic ferny azolla Azolla pinnata x x 2 Free floating Non-‐invasive exotic bladderwort, yellow bladderwort Utricularia gibba x X x x x x X x x x X 11 Submerged tall pondweed Invasive exotic hornwort, coontail Ceratophyllum demersum x x x 3 Submerged tall pondweed Invasive exotic lakeweed, egeria Egeria densa x x x 3 lagarosiphon, lakeweed, oxygen x 1 Submerged tall pondweed Invasive exotic weed Lagarosiphon major curly leaved pondweed, curled x x 2 Submerged tall pondweed Non-‐invasive exotic pondweed Potamogeton crispus Erect emergent Native oioi, jointed wire rush Apodasmia similis x x x x x x 6 Erect emergent Native kiokio, horokio, palm leaf fern Blechnum novazelandiae x 1 Erect emergent Native maori sedge Carax maorica x x 2 Erect emergent Native pukio Carex secta x 1 Erect emergent Native swamp sedge, pukio, toitoi, toetoe Carex virgata x 1 Erect emergent Native swamp coprosma, hukihuki Coprosma tenuicaulia x 1 Erect emergent Native cabbage tree, ti, ti kouka, palm lily Cordyline australis x 1 Erect emergent Native giant umbrella sedge, Upokotangata Cyperus ustulatus x x 2 Erect emergent Native sharp spike sedge Eleocharis acuta x x x x x x 6

x x x x x x x x x x x x x x x x x x x x x x 22 Erect emergent Native bamboo spike sedge, tall spike sedge Eleocharis sphacelata Erect emergent Native wire rush, lesser wire rush Empodisma minus x x 2 Empodisma robusta x x 2 Erect emergent Native wire rush, lesser wire rush (haplotype of E. minus) Juncus kraussii var. x 1 Erect emergent Native sea rush australiensis Erect emergent Native leafless rush Juncus pallidus x 1 Erect emergent Native manuka, tea tree, kahikatoa Leptospermum scoparium x 1 Machaerina arthrophylla (syn. x x x x x x 6 Erect emergent Native sedge Baumea arthrophylla) Machaerina articulata (syn. x x x x x x x x x x x x x x 14 Erect emergent Native jointed baumea, jointed twig rush Baumea articulata) Machaerina juncea (syn. x x x x x x x 7 Erect emergent Native sedge, tussock swamp twig rush Baumea juncea) Machaerina rubiginosa (syn. x x x 3 Erect emergent Native baumea Baumea rubiginosa) Machaerina teretifolia (syn. x x x 3 Erect emergent Native pakihi rush Baumea teretifolia) Erect emergent Native flax, harakeke, korari Phormium tenax x x x x 4 softstem bulrush, grey club-‐rush, Schoenoplectus x x x x 4 Erect emergent Native great bulrush tabernaemontani Erect emergent Native burr-‐reed, maru Sparganium subglobosum x x 2 Erect emergent Native raupo Typha orientalis x x x x x x x x x x x x x x x 15 Erect emergent Rare native none known Cyclosorus interuptus x x 2 swamp blueberry, swamp ink berry, x 1 Erect emergent Rare native swamp Dianella Dianella haematica Erect emergent Rare native pygmy sundew Drosera pygmaea x x 2 Erect emergent Rare native Marsh fern, swamp fern Thelypteris confluens x 1 Erect emergent Rare native Royal Fern, Hard todea, King fern Todea barbara x x x 3 Sprawling emergent Native centella Centella uniflora x 1 Sprawling emergent Native tangle fern, swamp umbrella fern Gleichenia dicarpa x x 2 Sprawling emergent Native swamp millet Isachne globosa x x x x 4 Sprawling emergent Native swamp willow weed Persicaria decipiens x x x 3 Sprawling emergent Rare native New Zealand sneezewort Centipeda aotearoana x 1 Sprawling emergent Rare native sneezeweed, centipeda Centipeda minima x 1 native hibiscus, swamp hibiscus, x x 2 Sprawling emergent Rare native prickly hibiscus Hibiscus diversifolius native musk, maori musk, native x 1 Sprawling emergent Rare native monkey flower Mimulus repens Low growing turf Native starwort Callitriche petriei x 1 Low growing turf Native waterwort Elatine gratioloides x 1 Low growing turf Native none known Glossostigma diandrum x 1 Low growing turf Native none known Glossostigma elatinoides x x x x 4 Low growing turf Native none known (sedge) Isolepis prolifera x x x 3 Low growing turf Native Zelandiae chain sword Lilaeopsis novae-‐zelandiae x x x x x x 6 Low growing turf Native mudwort Limosella lineata x 1 Low growing turf Native waoriki Ranunculus amphitrichus x x 2 Sea primrose, shore pimpernel, water x 1 Low growing turf Native pimpernel, maakoako Samolus repens Low growing turf Native moss Sphagnum sp. x 1 Low growing turf Native arrow grass Triglochin striata x x x x x 5 Floating leaved Native red pondweed Potamogeton cheesemanii x x x x x x x x x x x x 12 Free floating Rare native none known (sedge) Isolepis fluitans x x 2 Submerged milfoil Native common water milfoil Myriophyllum propinquum x x x x x x x x x x 10 Submerged milfoil Native water milfoil Myriophyllum triphyllum x 1 Submerged milfoil Rare native Stout water milfoil Myriophyllum robustum x 1 Submerged milfoil Rare native small water milfoil Myriophyllum votschii x x x 3 Submerged tall pondweed Native blunt pondweed Potamogeton ochreatus x x x x x x x x x x x 11 Submerged tall pondweed Native horses mane weed, lakeweed Ruppia polycarpa x 1 Submerged tall pondweed Rare native bladderwort, yellow bladderwort Utricularia australis x x x x x x x x x x x 11 Submerged charophyte Native stonewort Chara australis x x x x x x x x x x x x x x x x 16 Submerged charophyte Native stonewort Chara fibrosa x x x x x x 6 Submerged charophyte Native stonewort Chara globularis x 1 Submerged charophyte Native stonewort Lamprothamnium sp. x 1 Submerged charophyte Native stonewort Nitella hyalina x 1 Submerged charophyte Native stonewort Nitella leonhardii x x x x x 5 Submerged charophyte Native stonewort Nitella pseudoflabellata X x x x 4 Submerged charophyte Native stonewort Nitella sp. aff. cristata x x x x x x x x x 9 Total Plant Diversity 12 13 13 15 5 20 9 7 4 13 28 11 8 31 7 12 3 8 10 6 8 23 6 4 16 Exotic Plant diversity 0343121003310111113113104 Native Plant Diversity 12 10 9 12 4 18 8 7 4 10 25 10 8 30 6 11 2 7 7 5 7 20 5 4 12

8.1.1.1.1. Lake Submerged Plant Index (LakeSPI) and Native Condition Index and Invasive Impact Index 23

LAKE WAIHOPO MANAGEMENT PLAN | Biological Characteristics

Three8.1.1.1.1. indices Lake Submerged are valuable Plant Indexfor considering (LakeSPI), theNative health Condition of aIndex lake’s and Submergedplant community; Plant Index LakeNative Submerged Condition Index Plant and InvasiveIndex, ImpactNative Index conditionare high Index and steady,and Invasive owning to Plantnative plant Index. diversity Three indices are valuable for considering the health and cover. Invasive Impact Index is relatively high due Nativeof a lake’s Condition plant community; Index Lake and Submerged Submerged Plant Plantto three Index exotic are species high being and present. steady, owning to native plant diversity and cover. Invasive Impact Index is relatively high due to three Index, Native condition Index and Invasive Plant exotic species being present. Index.

80 Lake Waihopo 70

50 Lake Submerged Plant Index 40 % Na[ve Condi[on Index % 30 Invasive Impact Index % 20

10 Submerged Plant Ecological Health Index Score 0 Excellent 75-100% High 50-75% Moderate 20-50% 1/1/2004 1/1/2005 1/1/2006 1/1/2007 1/1/2008 1/1/2009 1/1/2010 1/1/2011 1/1/2012 1/1/2013 Poor 1-20% Non-Vegetated 0% Ecological Submerged Plant Health Index Score 8.1.2. Fish fish diversity and no pest fish are present. However, TheExcellent table below displays the fish75 of -‐the100% upper the nationally threatened black mudfish have been reported from this lake but their current status needs AupöuriHigh Peninsula. Pest fish are shown50-‐75% in green and conservation species in pink. Lake Waihopo appears to be ascertained 20-‐50% inModerate yellow. The lake has a very low level of native Poor 1-‐20% Non-‐Vegetated 0% No Data

Conservation Degree common name species status of loss 8.1.2. Fish Waitahora lagoon Waitahora Lakes Te Werahi Lagoon Ngakeketa North/Te Paki Ngakeketa South Te Paki Dune Lake Pretty Kihona Wahakari Te Kahika Morehurehu Morehurehu 1 South 2 Morehurehu South Waihopo Yelavich Katavich Waiparera frequency golden bell frog Litoria Aurea x 1 hylidae tree frog Litoria x 1 Thegoldfish table belowCarassius auratus displays the fish of the upper Aupōuri Peninsula. Pest fish are xshown 1 Gambusia Gambusia affinis x x x 3 inrudd green andScardinius conservation erythrophthalmus species in pink. Lake Waihopo appears in yellow. The? lake 1 shortfinned eel Anguilla australis x x x x x x 6 haslongfinned a very eel Anguillalow level dieffenbachii of nativeat risk fish decliningdiversity and no pest fish are present. However,x 1 the nationallyeel threatenedAnguilla sp black mudfish have been reported fromx this lake but their 1 inanga Galaxias maculatus at risk declining x x x 3 currentcommon bully statusGobiomorphus needs cotidianus to be ascertained x x x x x x x x x x x 11 grey mullet Mugil cephalus x x x x 4 black mudfish Neochanna diversus at risk relict x 1 smelt Retropinna retropinna x 1 diversity pest fish 00000000100000013 diversity native 10212113313111124

8.1.3. Waterbirds

The table below displays the waterbirds of the Aupōuri Peninsula (north of Sweetwater). Game birds are shown in green and non-game bird native species in pink. Canada goose is an exception as a non-game bird able to be hunted year- 24 round. Lake Waihopo appears in yellow. The lake has a high level of bird diversity and has no game species recorded. Of interest is the sole record of chestnut- breasted shelduck in this region in 2000.

Conservation Criteria / status ( DOC: Conservation status Degree of common name species , 2016) loss of Not threatened NZ birds lagoon Waitahora Lakes Waitahora Te Werahi Lagoon Ngakeketa Paki North/Te Ngakeketa South Lake Dune Paki Te Austria Pretty Waipara/Dead Kihona Wahakari Te Kahika Te Kahika South Morehurehu Morehurehu South 1 Morehurehu South 2 Taeore (dried out) Lake Te Arai Te Arai Wetland Ephemeral Bulrush Salt Waihopo Yelavich Katavich Waiparera frequency Anas rhynchotis (resident native (resident x Australasian (NZ) shoveler (not introduced) on game bird list) native) 1 Cygnus atratus (resident native (not x x x x x black swan introduced) on game bird list) Not threatened 5 Porphyrio m. melanotus (resident native (not introduced) on game x x pukeko bird list) not threatened 2 Tardorna variegata (resident native x x x x x x paradise shelduck (not introduced) on game bird list) Not threatened 6 Branta canadensis (Introduced & naturalised, not protected, able to Introduced & x x x x Canada goose be hunted at any time) naturalised 4 brown teal Anas chlorotis at risk recovering x 1 New Zealand scaup Aythya novazeelandiae not threatened x x x x 4 nationally x x x x x x x Australasian bittern Botaurus poiciloptilus threatened critical 7 North Island fernbird Bowdleria punctata vealeae at risk declining x x x x x x x x x x x x x 13 nationally x Caspian tern Hydroprogne caspia threatened vulnerable 1 naturally x little black shag Phalacrocorax sulcirostris at risk uncommon 1 pied shag Phalacrocorax v. varius at risk recovering x x 2 New Zealand dabchick Poliocephalus rufopectus at risk recovering x x x x x x 6 marsh crake Porzana pusilla affinis at risk declining x 1 spotless crake Porzana t. tabuensis at risk declining x x x x 4 Australasian little grebe Tachybaptus n. novaehollandiae coloniser x 1 chestnut-‐breasted shelduck Tadoma tadornoides vagrant x 1 diversity resident native (not introduced) on game bird list 0 0 1 3 2 0 0 0 0 3 0 0 0 0 0 0 0 0 1 0 1 0 0 1 2 diversity introduced & naturalised 0 0 1 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 1 0 0 0 0 0 0 diversity native 3 2 0 1 1 1 5 0 2 2 3 5 0 2 1 1 0 3 0 1 0 6 0 1 2

8.1.4. Invertebrates

Invertebrates are of interest in lake systems as indicators of lake health. They are generally very sensitive to poor water quality. In the case of Waihopo, no species which are sensitive to poorer states of water quality are present, although diversity is

Conservation Degree common name species status of loss Waitahora lagoon Waitahora Lakes Te Werahi Lagoon Ngakeketa North/Te Paki Ngakeketa South Te Paki Dune Lake Pretty Kihona Wahakari Te Kahika Morehurehu Morehurehu 1 South 2 Morehurehu South Waihopo Yelavich Katavich Waiparera frequency golden bell frog Litoria Aurea x 1 hylidae tree frog Litoria x 1 goldfish Carassius auratus x 1 Gambusia Gambusia affinis x x x 3 rudd Scardinius erythrophthalmus ? 1 shortfinned eel Anguilla australis x x x x x x 6 longfinned eel Anguilla dieffenbachii at risk declining x 1 eel Anguilla sp x 1 inanga Galaxias maculatus at risk declining x x x 3 common bully Gobiomorphus cotidianus x x x x x x x x x x x 11 grey mullet Mugil cephalus x x x x 4 black mudfish Neochanna diversus at risk relict x 1 smelt Retropinna retropinna x 1 diversity pest fish 00000000100000013 diversity native 10212113313111124 LAKE WAIHOPO MANAGEMENT PLAN | Biological Characteristics 8.1.3. Waterbirds 8.1.3. Waterbirds non-game bird able to be hunted year-round. Lake The table below displays the waterbirds of the Aupōuri Peninsula (north of The table below displays the waterbirds of the Waihopo appears in yellow. The lake has a high level Sweetwater). Game birds are shown in green and non-game bird native species in Aupöuri Peninsula (north of Sweetwater). Game of bird diversity and has no game species recorded. pink. Canada goose is an exception as a non-game bird able to be hunted year- Of interest is the sole record of chestnut-breasted birdsround. are shownLake Wain greenihopo and appea non-gamers in bird yellow. native The lake has a high level of bird diversity shelduck in this region in 2000. speciesand has in pink. no gameCanada speciesgoose is an recorded exception .as Of a interest is the sole record of chestnut- breasted shelduck in this region in 2000.

8.1.4. Invertebrates

25 LAKE WAIHOPO MANAGEMENT PLAN | Land Use

8.1.4. Invertebrates which are sensitive to poorer states of water quality are Invertebrates are of interest in lake systems as indicators present, although diversity is highest out of all Aupöuri of lake health. They are generally very sensitive to lakes, probably due to the health of submerged poorhighest water out quality. of Inall the Aup caseō ofuri Waihopo, lakes, noprobably species duevegetation to the and health the lakes of productivity.submerged vegetation and the lakes productivity.

Pollution minimum tolerance -‐ Clean Water (>5.99) Mild Pollution (5.00-‐5.90) Moderate Pollution (4.00-‐4.99) Order or phylum and common name Family or species Severe Pollution (<4.00) Waitahora lagoon Waitahora Lakes Te Werahi Lagoon Ngakeketa North/Te Paki Ngakeketa South Dune Lake Paki Te Austria Pretty Waipara/Dead Kihona Wahakari Te Kahika South Te Kahika Morehurehu Morehurehu South 1 Morehurehu South 2 Taeore (dried out) Te Arai Lake Te Arai Ephemeral Wetland Bulrush Salt Waihopo Yelavich Katavich Waiparera frequency Mollusc, snail Physa (Physella) acuta 0.1 x x x x x 5 Mollusc, snail Pseudosuccinea x 1 Coleoptera, dytiscid diving beetle Onychohydrus hookeri x x 2 Coleoptera, whirigig beetle Gyrinus x x x 3 Crustacea, Isopoda Sphaeromatoidea 4.5 x 1 Crustacea, Ostracoda, koura Paranephrops planifrons 8.4 0 Diptera, midge, non-‐biting, Chironomid Chironomas sp 3.4 x x x x x x x 7 Diptera, midge, non-‐biting, Chironomid Orthocladiinae 3.2 x x 2 Diptera, midge, non-‐biting, Chironomid Tanypodinae 6.5 x 1 Diptera, non-‐biting midge, Chironomid Parachironomus x 1 Hemiptera, bug, backswimmer Anisops 2.2 x x x x x x x 7 Hemiptera, bug, backswimmer Sigara arguta 2.4 x x x x x x 6 Hemiptera, bug, waterboatman Diaprepocoris sp 4.7 x x x 3 Hemiptera, bug, waterboatman Corixidae sp x x 2 Hirudinea, leech Alboglossiphonia x 1 Hirudinea, leech Richardsonianus mauianus x 1 Hydrozoa, hydra Hydra sp x 1 Lepidoptera, aquatic moth Hygraula nitens 1.3 x 1 Mollusca, freshwater mussel Hyridella menziesi 6.7 shells x 2 Mollusca, pea mussel Musculium novazelandiae x x x x x ? 6 Mollusca, pea mussel Sphaerium novaezelandiae x 1 Mollusca, snail Gyraulus corinna 1.7 x 1 Mollusca, snail, native Potamopyrgus antipodarum 2.1 x x x x x x 6 Neuroptera, spongillafly larvae Sisyra x x 2 Odonata, damselfly Xanthocnemis sp 1.2 x x x x x x x x x x 10 Odonata, dragonfly Hemicordulia australiae 0.4 x x x x x 5 Odonata, dragonfly sp x x x x 4 Porifera, freshwater sponge sp x x x x x x x 7 Trichoptera, caddisfly Leptoceridae x 1 Trichoptera, caddisfly Oecetis unicolor 6.8 x 1 Trichoptera, caddisfly Paroxyethira hendersoni 3.7 x x ? 3 Trichoptera, caddisfly sp x 1 Trichoptera, caddisfly Triplectides sp 5.7 x 1 diversity invasive 000 0 0000020000000101010016 diversity native 0 0 0 9 5 9 0 0 11 6 3 10 0 5 2 0 0 1 0 9 0 12 0 0 8

9. Land Use

9. LAND USE 9.1. Catchment land cover table and map 9.1. Catchment land cover table and mapThe lake is situated in a catchment dominated by high producing grassland, closed canopy exotic pine forest and freshwater sedgeland/rushland. The lake is situated in a catchment dominated by high producing grassland, closed canopy exotic pine forest Total FENZ Total Hand-‐ andLake freshwater sedgeland/rushland.Cover Type (ha) drawn (ha) Waihopo Lake Exotic Forest 47.92 74.06 Waihopo Lake Herbaceous Freshwater Vegetation Total FENZ10.67 Total Hand-13.27 LakeWaihopo Lake CoverHigh Type Producing Exotic Grassland (ha) 38.99drawn (ha)92.33 Waihopo Lake Exotic Forest 47.92 74.06 Waihopo Lake Lake or Pond 6.80 7.86 Waihopo Lake Herbaceous Freshwater Vegetation 10.67 13.27 Waihopo Lake Orchard, Vineyard or Other Perennial Crop 0.00 1.36 Waihopo Lake High Producing Exotic Grassland 38.99 92.33 Waihopo Lake Total 104.39 188.87 Waihopo Lake Lake or Pond 6.80 7.86 Grand Total 14034.62 9575.00 Waihopo Lake Orchard, Vineyard or Other Perennial Crop 0.00 1.36 Waihopo Lake Total 104.39 188.87 Grand Total 14034.62 9575.00

LAKE WAIHOPO MANAGEMENT PLAN | Land Use

9.2. Pastoral farming and horticulture

9.2.1. Drains

A key issue for Waihopo is the influence of land drains entering the lake, increasing nitrogen inputs, which is prompting excessive reed growth and infilling the shallows into a wetland environment. This is not uncommon for shallow lakes to eventually 9.2. Pastoral farming and 9.4. Fire-fighting mitigationsbecome wetland, but the influence on drainage is accelerating this beyond the natural, longer-term geological timeframe. horticulture Waihopo, like other lakes in the immediate region, 9.3. Forestry 9.2.1. Drains are a moderate risk (orange square) for use as a water Forestry in the catchment will likely contribute to nutrient loads, specifically at source for forest fire-fighting usingfertilisation helicopter, harvest andtimes and during the break-down of material post-harvest. The A key issue for Waihopo is the influence of land drains phosphorusbuckets. spikes Waihopo observed is may at have risk come due from to thisits sourcedepth, linked being back to soil entering the lake, increasing nitrogen inputs, which disturbance. 31 under the four-metre limit for bottom damage from is prompting excessive reed growth and infilling the 9.4. Fire-fighting mitigations fire buckets, as well as posing a biosecurity risk to shallows into a wetland environment. This is not Waihopo, like other lakes in the immediate region, are a moderate risk (orange square)other for water use as abodies water source due for to forest the fire presence-fighting using of helicopter the exotic and bucke ts. uncommon for shallow lakes to eventually become Waihopo is at risk due to its depth being under the four-metre limit for bottom 9.2. Pastoral farming and horticulture damagebladderwort, from fire buckets, Utricularia as well as gibba posing a. biosecurity risk to other water bodies due to the presence of the exotic bladderwort, Utricularia gibba. wetland, but the influence on drainage is accelerating 9.2.1. Drains this beyond the natural, longer-term geological timeframe.A key issue for Waihopo is the influence of land drains entering the lake, increasing nitrogen inputs, which is prompting excessive reed growth and infilling the shallows into a wetland environment. This is not uncommon for shallow lakes to eventually become wetland, but the influence on drainage is accelerating this beyond the 9.3.natural, longerForestry-term geological timeframe.

Forestry9.3. Forestryin the catchment will likely contribute to nutrient loads, specifically at fertilisation, harvest times Forestry in the catchment will likely contribute to nutrient loads, specifically at andfertilisation during ,the harvest break-down times and of materialduring the post-harvest. break-down of material post-harvest. The The phosphorus spikes observed may have come from this source, linked back to soil disturbance. 31

10. Monitoring Plan

The map below shows the five transect lines surveyed during ecological surveys. The dark triangle on the northern shore is the access point for the NRC vessel for water quality sampling. The pink point in the middle of the lake is the water quality sampling point, corresponding to the deepest part of the basin.

LAKE WAIHOPO MANAGEMENT PLAN | Monitoring Plan

10. MONITORING PLAN The map (right) shows the five transect lines surveyed during ecological surveys. The dark triangle on the northern shore is the access point for the NRC vessel for water quality sampling. The pink point in the middle of the lake is the water quality sampling point, corresponding to the deepest part of the basin.

10.1. NIWA ecological monitoring KEY 10.1. NIWA ecological monitoring O = Outstanding The lake is scheduled to be fully ecologically HThe = High lake is scheduled to be fully ecologically monitored every five years. There have monitored every five years. There have been seven Mbeen = Medium seven full surveys since 1985. The value class of the lake began at L=Outstanding Low and was down-graded to High in 2013. The next full survey is likely to be full surveys since 1985. The value class of the lake Ecologicaldone in Survey 2022. Reconnaissance or Visit began at Outstanding and was down-graded to High WeedKEY Surveillance GrassO = Outstanding Carp Assessment in 2013. The next full survey is likely to be done in H = High EndothallM = Medium Assessment L= Low 2022. SPIEcological = Submerged Survey Plant Index Reconnaissance or Visit SurveillanceWeed Surveillance Grass Carp Assessment Endothall Assessment Eco Weed SPI = Submerged Plant Index Surveillance Survey survey Lake (yr) (yr) 1984 1985 1986 1987 1988 1989 1990 1991 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 Austria M M Bulrush L Half Mile Lagoon L Katavich L Kihona L SPI Morehurehu 1 H O O H H H Morehurehu South 1 L-‐M Morehurehu South 2 1 HH M M M Ngakeketa L SPI Ngakeketa North/Te Paki 5 H M-‐H Ngatuwhete L Pretty M M-‐H SPI Salt (Taumatawhaua) L Taeore L-‐M Te Arai Ephemeral Wetland M Te Arai Lake L Te Kahika 5 OO H M-‐H M-‐H Te Kahika East 33 Te Kahika South 5 H Te Paki dune 5 H O H H

Te Paki Stream 1 (nearest carpark) Te Paki Stream 2 (nearest sea) Te Werahi Lagoon H M Wahakari 5 1 O O O O Waihopo 5 O O O H Waipara/Dead H H Waiparera 5 M-‐H M-‐H Waitahora lagoon 10 OO O Waitahora Lakes 10 M M M Yelavich 5 H H M-‐H

10.2. NRC Ecological monitoring

28 10.2.1. Water quality and quantity monitoring

Water quality sampling occurs quarterly in February, May, August and November. Number of samples per year are shown below.

Row Labels 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Grand Total Waihopo lower 1444343444451 45 Waihopo surface 1444444444451 47

10.2.1.1.1. Lake level

Installation of a staff gauge and a continuous electronic water-level recorder is proposed.

11. Work implementation plan

Ongoing work includes:

The NRC/NIWA ecological surveys will continue every five years. The next full survey will be in 2022. Quarterly NRC water quality monitoring will continue.

Freshwater Improvement Fund work, due to begin in early 2018, includes nutrient mitigation modelling and mitigation, especially of the main drain entering the lake for which $5000 in earthworks has been dedicated for this action. The project will include a catchment assessment which will result in recommendations for any further mitigation works required.

Further mitigation work to consider includes:

• Waihopo, like other lakes in the immediate region, are a moderate risk for use as a water source for forest fire-fighting using helicopters. Waihopo is at risk due to its depth being under the four metre limit for bottom damage from fire buckets, as well as posing a biosecurity risk to other water bodies due to the presence of the exotic bladderwort, Utricularia gibba.

Eco Weed Survey survey Lake (yr) (yr) 1984 1985 1986 1987 1988 1989 1990 1991 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 Austria M M Bulrush L Half Mile Lagoon L Katavich L Kihona L SPI Morehurehu 1 H O O H H H Morehurehu South 1 L-‐M Morehurehu South 2 1 HH M M M Ngakeketa L SPI Ngakeketa North/Te Paki 5 H M-‐H Ngatuwhete L Pretty M M-‐H SPI Salt (Taumatawhaua) L Taeore L-‐M Te Arai Ephemeral Wetland M Te Arai Lake L Te Kahika 5 OO H M-‐H M-‐H Te Kahika East Te Kahika South 5 H Te Paki dune 5 H O H H

Te Paki Stream 1 (nearest carpark) Te Paki Stream 2 (nearest sea) Te Werahi Lagoon H M Wahakari 5 1 O O O O Waihopo 5 O O O H Waipara/Dead H H Waiparera 5 LAKE WAIHOPO MANAGEMENTM-‐H M-‐H PLAN | Work Implementation Plan Waitahora lagoon 10 OO O Waitahora Lakes 10 M M M Yelavich 5 H H M-‐H

10.2. NRC Ecological monitoring Number of samples per year are shown below. 10.2. NRC Ecological monitoring 10.2.1. Water quality and quantity 10.2.1.1.1. Lake level monitoring10.2.1. Water quality and quantity monitoring Installation of a staff gauge and a continuous Water quality quality sampling sampling occurs quarterlyoccurs inquarterly February, in February,electronic water-level May, August recorder and is proposed. November . May,Number August of and samples November. per year are shown below.

11. WORK IMPLEMENTATION10.2.1.1.1. Lake PLANlevel Cawthron Institute for the Northland Regional Council, 2016. Kelly, D., L. Peacock and W. Jiang, 2016. Nutrient Ongoing work includes: Installation of a staff gauge and a continuousManagement electronic for water Northland’s-level Dune recorder Lakes. is •proposed. The NRC/NIWA ecological surveys will continue every five years. The next full survey will be in Department of Conservation, Freshwater Ecosystems of 11.2022. Work Quarterly implementation NRC water quality plan monitoring will New Zealand (FENZ) database, www.doc.govt.nz/our- continue. work/freshwater-ecosystems-of-new-zealand. Ongoing work includes:

• Freshwater Improvement Fund work, due to Doole, G. and D. Marsh, 2015. Conceptual modelling The NRC/NIWA ecological surveys will continue every five years. The next full survey of shallow dune lakes in the Northland region of New willbegin be inin early2022. 2018, Quarterly includes nutrient NRC watermitigation quality monitoring will continue. Zealand. modelling and mitigation, especially of the main Freshwaterdrain entering Improvement the lake for which Fund $5000 work, in due to begin in early 2018, includes nutrient Jacobs for the Northland Regional Council, 2017. mitigationearthworks modelling has been dedicated and mitigation, for this action. especially The of the main drain entering the lake for Hydrological Assessment for Potential Window Lakes whichproject $5000 will include in earthworks a catchment assessmenthas been which dedicated for this action. The project will include (Update). a catchmentwill result in recommendations assessment whichfor any furtherwill result in recommendations for any further mitigationmitigation worksworks required. required. LWP for Northland Regional Council, 2016. Lake Further mitigation work to consider includes:FMUs for Northland, Recommendations for Policy Further mitigation work to consider includes: development. • Waihopo,• Waihopo, like other lakeslike otherin the immediate lakes in region, the immediate region, are a moderate risk for use are a moderateas a water risk for source use as a forwater forest source fire for -fightingMinistry using for the helicopters Environment,. Waihopo2014. National is Policyat risk forest fire-fightingdue to its depth using helicopters. being under Waihopo the is fourStatement metre limit for Freshwater for bottom Management damage 2014. from fire at risk duebuckets, to its depth as wellbeing asunder posing the four a metre biosecurity risk to other water bodies due to the limit forpresence bottom damage of the from exotic fire buckets, bladderwort, as well UtriculariaNicol, E. R., 1997. gibba Common. Names of Plants in New as posing a biosecurity risk to other water bodies Zealand, Press, Lincoln, Canterbury, New Zealand, Manaki Whenua press. due to the presence of the exotic bladderwort, Utricularia gibba. 34 NIWA for the Ministry for the Environment, 2002. • Installation of a staff gauge and a continuous Champion, P., J. Clayton and D. Rowe, 2002. Lake electronic water-level recorder is proposed. Manager’s Handbook, Alien Invaders.

NIWA for the Ministry for the Environment, 2002. 12. BIBLIOGRAPHY Rowe, D. and E. Graynoth, 2002. Lake Manager’s AgResearch Ltd. for Northland Regional Council 2016. Handbook, Fish in New Zealand Lakes. Lucci, G., 2016. Revisiting the Guidelines for Pastoral Management in the Catchment of Dune Lakes in NIWA for the Northland Regional Council, 2012. Northland. Champion, P. and de Winton, M. (2012). Northland Lakes Strategy, NIWA Project: ELF12213, NIWA Client

29 LAKE WAIHOPO MANAGEMENT PLAN | Appendix 1

Report No: HAM2012-121, prepared for Northland Te Puni Kokiri, Te Kähui Mängai (Directory of Iwi and Regional Council: 42. Mäori Organisations) http://www.tkm.govt.nz

NIWA for the Northland Regional Council, 2014. Timms, B.V., 1982. Coastal dune waterbodies of north- Champion, P. (2014) Northland Lakes Strategy Part eastern New South Wales. II update and implementation strategy. NIWA Client Report No: HAM2014-038, prepared for Northland Australian Journal of Marine and Freshwater Research Regional Council: 35. 33: 203–222.

NIWA for the Department of Conservation, 1996. 13. APPENDIX 1. GLOSSARY Collier, K. J. 1996. Potential impacts of plantation Largely adapted from https://www.lawa.org.nz/Learn forestry on dune lakes in Northland with interim guidelines for riparian management. Aquatic - Refers to anything that is related to water. For example, aquatic organisms are plants or animals NIWA for the Northland Regional Council, 2015. de that live in or near water. Winton, M., Taumoepeau, A. and Macdonald, A. (2015). Northland Lakes hydro-acoustic survey and Algal or phytoplankton bloom - A rapid increase in bathymetric resources, NIWA CLIENT REPORT No: the population of algae in an aquatic system. Blooms HAM2015-116, Prepared for Northland Regional can reduce the amount of light and oxygen available to Council. 56 pp. other aquatic life.

NIWA for the Northland Regional Council, 2014. Rowe, Bathymetry – The measurement of depth of water. D., 2014. Biosecurity status of non-native freshwater fish species in Northland. Biodiversity - The variety of lifeforms at a given time in a given place. NIWA for the Northland Regional Council, 2014. Wells, R., and P. Champion, 2014. Northland Lakes Ecological Biosecurity - The precautions taken to protect against Status 2014. the spread harmful organisms and diseases.

NIWA for the Northland Regional Council, 2014. Wells, Catchment (area) - The total area of land draining into R., P. Champion and T. Edwards, 2014. Northland Lakes a lake, expressed in hectares (ha). – Annual Report 2014. Chlorophyll a – Chlorophyll a is a green pigment in NIWA for the Northland Regional Council, 2015. Wells, all plants, including algal phytoplankton, that is used R. and P. Champion, 2015. Northland Lakes – Annual for photosynthesis and is a good indicator of the Report 2015. total quantity of algae present. It can be measured in micrograms per litre (ug/l) or reflective florescence units NIWA for the Northland Regional Council, 2016. Wells, (RFU). Large amounts of algae in a lake can decrease R. and P. Champion, 2016. Northland Lakes – Annual the clarity of the water, make the water green, form Report 2016. surface scum, reduce dissolved oxygen and alter the pH of the water. Northland Regional Council, 2013. Cathcart, B., 2013. Soils of Northland. Clarity (of water) - Refers to light transmission through water and has two important aspects: visual Northtec for Northland Regional Council, 2009. Ball, clarity and light penetration. Visual clarity indicates O. J.-P., S. R. Pohe and M. J. Winterbourn, 2009. The how much sediment or runoff is in the water. Light littoral macroinvertebrate fauna of 17 dune lakes of the penetration is also important as it controls light Aupöuri Peninsula, Northland. availability for growth of aquatic plants.

30 LAKE WAIHOPO MANAGEMENT PLAN | Appendix 1

Classification of dune lakes (Timms, 1982) Dune lake class (Timms, 1982) Description 1. Perched lakes in deflation hollows Perched in leached dunes, in deflation hollows in elevated leached dunes where organic material has sealed the basin floor and provided humic (tea-stained) water. 2. Swamp-associated perched lakes Similar to Class 1 but close to the sea, associated with extensive swamps. 3. Window lakes Water table window lakes in a drowned valley or interdune basin, fed by springs with clear water character. 4. Dune contact lakes Waterbodies where at least one shore is in contact with a coastal dune, often but not exclusively humic. 5. Marine contact lakes Freshwater lakes with marine contact, where there may be intermittent connection with the sea. 6. Ponds in frontal sand dunes Ponds where wind erodes sand to form deflation hollows.

Deoxygenation – Also called hypoxia. Air is 20.9% oxygen in summer resulting in potential death of oxygen, whereas water contains around 1% oxygen animal life. In the Trophic Level Index (TLI), a trophic and this fluctuates depending on the presence level of 4-5, meaning the water quality is poor. of photosynthetic organisms (higher submerged plants and microalgae) and the distance to the Exotic species (also called introduced, alien, non- surface, as air diffuses oxygen into surface waters. indigenous or non-native) - A species living outside Hypoxia can occur throughout the water column its native distributional range, which has arrived as well as near sediments on the bottom. It usually by human activity, either deliberate or accidental. extends throughout 20-50% of the water column, Exotic species can have various effects on the local but depending on the water depth, it can occur in ecosystem. Exotic species that become established 10-80% of the water column. For example, in a and spread beyond the place of introduction are 10-meter water column, it can reach up to 2 meters called invasive species. below the surface. In a 20-meter water column, it can extend up to 8 meters below the surface. Oxygen Hapü - Te reo Mäori for a sub-tribe or a clan. Each depletion can result from a number of natural iwi can have a number of hapü. For example, the factors, but is most often a concern as a consequence Ngäti Whätua iwi has hapü including Te Uri-o-Hau, of pollution and eutrophication in which plant Te Roroa, Te Taou, and Ngäti Whätua ki öräkei. nutrients enter a lake, and phytoplankton blooms are encouraged. While phytoplankton, through Humic - Of, relating to, or derived from humus, photosynthesis, will raise Dissolved Oxygen (DO) which is a dark brown or black mass of partially saturation during daylight hours, the dense decomposed organic matter in the soil. Humic acids population of a bloom reduces DO saturation during are present in peats. Humic acids are produced by the night by respiration. When phytoplankton the bacterial decomposition of dead plant residues cells die, they sink towards the bottom and are and by the prolonged action of atmospheric oxygen decomposed by bacteria, a process that further or water on organic matter. Run-off from land of this reduces DO in the water column. If oxygen depletion soil type can stain lake-water a dark brown (known progresses to hypoxia, fish kills can occur and as humic or tanin staining), limiting light for plant invertebrates like freshwater mussels on the bottom growth. Forestry harvest has been shown to disturb may be killed as well. this soil type, leading to lake water quality decline.

Dissolved oxygen (DO) - The oxygen content of Invasive exotic plant – An exotic species that water. Dissolved oxygen is important for fish and becomes established and spreads beyond the place other aquatic life to breathe. For example, water of introduction, posing a risk to native ecology. quality guidelines recommend that water should be more than 80 percent saturated with DO for aquatic Invasive Impact Index - The percentage of invasive plants and animals to be able to live in it. weeds within a lake. A high Invasive Impact is undesirable. Eutrophic – A trophic level referring to a lake having an abundant accumulation of nutrients that support Invertebrate - An animal that has no backbone or a dense growth of algae and other organisms, the spinal column, such as insects, worms, snails and decay of which may deplete the shallow waters of freshwater mussels.

31 LAKE WAIHOPO MANAGEMENT PLAN | Appendix 1

Lake Submerged Plant Index (SPI) - A method of nutrients and algae, high oxygen levels due to a lack characterizing the ecological health of lakes based on or decaying organic material. The lake is clear and the amount of native and invasive plants growing in blue, with very low levels of nutrients and algae. them. Higher Lake SPI scores are associated with the better ecological health. pH - The degree of acidity or alkalinity as measured on a scale of 0 to 14 where 7 is neutral, less than 7 Limiting nutrient assay – An analytic procedure is more acidic, and greater than 7 is more alkaline. to determine what nutrient is limiting algal growth Most natural waters fall within the range between pH in a lake. If the limiting nutrient becomes available, 6.5 to 8.0 and in the absence of contaminants most increased growth of algal phytoplankton will occur. waters maintain a pH value that varies only a few tenths of a pH unit. Macrophyte - Large water plants and algae that live in freshwater and are visible to the naked Phytoplankton - Microscopic algae and eye, as opposed to the microscopic periphyton cyanobacteria that drift or float in the water and phytoplankton. Macrophytes can be either column and are able to produce oxygen through submerged, floating or emergent. Most macrophytes photosynthesis. When overgrowth or algal bloom in Northland are rooted to the bottom. occurs, it is an indication that excess nutrients are a problem. Algal blooms can shade light from Mana whenua – Te reo Mäori for territorial rights, reaching submerged plants and if a bloom collapses, power from the land, authority over land or territory, deoxygenation of the water may occur. jurisdiction over land or territory - power associated with possession and occupation of tribal land. The Quaternary dunes – We are currently still living tribe’s history and legends are based in the lands in the Quaternary period of geological time. The they have occupied over generations and the land Quaternary period is subdivided into the Pleistocene provides the sustenance for the people and to epoch (2.6 million years ago to 11,700 years ago), provide hospitality for guests. the Holocene epoch (11,700 years ago to 1950) and the Anthropocene epoch (1950-present or the Mesotrophic - A trophic level of 3-4 meaning the period when the Industrial Revolution began to alter water quality is average. The lake has moderate levels climate). When we refer to dune sand types, they are of nutrients and algae. informally divided into Early/Lower Quaternary (dunes formed 2.6 million-78,000 years ago) and Late/Upper Native Condition Index - The percentage of native Quaternary (dunes formed 12,000 years ago to the vegetation within a lake. A high native condition is present, basically during the Holocene epoch). desirable. It is one of the measures used to determine the Lake Submerged Plant Index. The material in present-day river valleys and beaches has been mainly deposited since the last glacial stage Native species (also indigenous species) - A ended, about 14 000 years ago. From then, until about species found naturally in an ecosystem, including 6000 years ago, there was a substantial warming of naturally-arriving migrant species which may be climate which caused a rise in sea level; some dune found in other countries as well. Endemic natives are deposits are recognised as having formed at the time found only in one place or country. that sea level rise ended.

Non-invasive exotic plant - Exotic species of plants Sea level has dropped again slightly since that time. that become established and do not readily spread Lakes are collecting mud and sand and will eventually beyond the place of introduction, posing little threat fill. Sand dunes naturally advance, blown by the wind to native species. until stabilised by vegetation.

Oligotrophic - A trophic level of 2-3 meaning the Periods of cold climate occurred throughout the water quality is good. The lake has low levels of Quaternary, not only in New Zealand but globally. The

32 LAKE WAIHOPO MANAGEMENT PLAN | Appendix 1 worldwide glaciations caused sea level to drop, as much Supertrophic - A trophic level greater than 5 meaning water was bound up in ice and snow. During warmer the water quality is very poor. The lake is fertile and interglacial periods, the ice melted and sea level rose. saturated in phosphorus and nitrogen, often associated The effect of these oscillating sea levels is clearly seen in with poor water clarity. uplifted coastal terraces, each flat surface marking the position of an earlier high sea level. Periods of low sea Thermal stratification - Refers to a change in the level and cold climate created expanses of bare earth lake water temperature at different depths in the and sand with little vegetation. Winds blew the coastal lake, and is due to the change in water’s density with sand into dunes. In the North Island, there was little temperature. Cold water is denser than warm water active glaciation except in the very highest mountain and the epilimnion, or shallower waters, generally areas. The build-up of sand dunes was a result of low consists of water that is not as dense as the water in sea levels and cold climate. the hypolimnion, or deeper waters. When stratification occurs, the two water masses are not mixing, leading Rare native plant - A rare plant is one that is not to nutrients and lower oxygen levels being captured in commonly found in the wild. It may be naturally rare or deeper, colder water. This generally occurs in warmer sparse or may have a restricted range. Rare plants may months. When the upper water cools in colder months, or may not be of conservation concern. A threatened mixing will occur, providing nutrients throughout the plant is a rare plant which is at risk of extinction in the lake, which can lead to algal bloom conditions. wild. An endangered plant is a category of threatened plant. It is a technical term for describing the degree of Total Phosphorus (TP) - Total phosphorus is a risk of extinction a plant is under. Some technical terms, measure of all forms of phosphorus that are found in such as endangered, are commonly and inaccurately a sample, including dissolved and particulate, organic used to refer to all threatened plants. and inorganic. High levels of total phosphorus in water can come from either wastewater or run-off from Residence time (also retention time, water age or agricultural land. Too much phosphorus can encourage flushing rate) – A calculated quantity expressing the the growth of nuisance plants such as algal blooms. mean time that water spends in a particular lake. Total Nitrogen (TN) - Total Nitrogen is a measure of all Riparian zone - A strip of land, usually of varying organic and inorganic forms of nitrogen that are found width, that is directly adjacent to a waterway and which in a sample. High total nitrogen, like total phosphorus contributes to maintaining and enhancing the natural can be a cause of eutrophication in lakes, estuaries and functioning, quality, and character of the waterbody. coastal waters and can cause algal blooms. This area is commonly planted in native species to reduce sediment and nutrient inflows. Total Suspended Solids (TSS) - Solids in water that can be trapped by a filter for measurement. TSS can Sp. aff. or aff. (short for “species affinis”) indicates include a wide variety of material, such as silt, decaying a potentially new and undescribed species has an plant and animal matter, industrial wastes, and sewage. affinity to, but is not identical to, the named species. High concentrations of suspended solids can adversely ... spp.; short for “species”) indicates potentially new affect aquatic life. species without remarking on its possible affinity. Trophic Level Index (TLI) - Used in New Zealand as a Secchi disk - Lake clarity is measured using a Secchi measure of nutrient status of lakes. The TLI is calculated disc attached to a measured line. The disc is lowered from data from 4 parameters: water clarity (Secchi), into the water until it disappears and this depth is chlorophyll a content, total phosphorus and total noted. The disc is lowered a little further and then nitrogen. slowly raised until it reappears, this depth is noted. The average of the two readings is the final Secchi depth Volumetric flow rate (as a mean annual total) - The visibility depth. amount of water entering a lake in a year, expressed in m3/s or cubic meters per second.

33 LAKE WAIHOPO MANAGEMENT PLAN | Appendix 1

Acknowledgements • The forestry industry for their open engagement and the farmers who are taking steps to protect these Sincere thanks to those who have generously provided lakes. their time to the twelve outstanding dune lake plans • The Ministry for the Environment and ratepayers project, including: of Northland for the Dune Lakes Freshwater • Lisa Forester for the guidance, support, knowledge Improvement Fund project which will address many and editing. of the actions in these plans over the next five years.

• Andrew Macdonald for countless analyses, data presentation and editing.

• Bruce Howse for guidance and support along the way.

• Katrina Hansen and Bruce Griffin in Biodiversity for their editing.

• Ngä Kaitiaki o ngä roto tähuna – Each iwi/hapu/ whanau and marae who have engaged in this process and in the korero and mahi to come.

• The NRC teams: Biodiversity, GIS, Biosecurity, Hydrology, State of the Environment, Area Offices in Dargaville and Kaitaia, Land Management, Consents, IS&T, Planning and Policy, Communications, Finance and our Kaiarahi who all made valuable contributions of time, information and thought.

• The Northland Regional Council councillors and our CEO Malcolm Nicolson who are passionate about our region and our lakes.

• Paul Champion and the team at NIWA for data provision and insight.

• Kevin Matthews of the Bushland Trust for local knowledge of the Aupouri and Karikari Peninsulas ecology.

• Graeme Doole at the Ministry for the Environment and Chris Tanner at the Cawthron Institute for the modelling approach to nutrient mitigation presented in the Humuhumu and Kanono plans.

• Our friends at DOC, Taharoa Domain Committee at Kaipara District Council and Lake Ngatu Action Group for collaborations.

• The Catchment Groups, especially Pouto and Doubtless Bay, for their lakes-related planning.