RUAKURA STRUCTURE PLAN AREA

Transcription

1 RUAKURA STRUCTURE PLAN AREA Assessment of Ecological Values to inform an Integrated Catchment Management Plan Prepared for Tainui Group Holdings Ltd & Chedworth Park Ltd 11 June 2013

2 Document Quality Assurance Bibliographic reference for citation: Boffa Miskell Limited RUAKURA STRUCTURE PLAN AREA: Assessment of Ecological Values to inform an Integrated Catchment Management Plan. Report prepared by Boffa Miskell Limited for Tainui Group Holdings Ltd & Chedworth Park Ltd. Prepared by: Louise Clark Associate Principal / Ecologist Boffa Miskell Limited Reviewed by: Sharon De Luca Principal / Ecologist Boffa Miskell Limited Status: FINAL Revision / version: 5 Issue date: 11 June 2013 Use and Reliance This report has been prepared by Boffa Miskell Limited on the specific instructions of our Client. It is solely for our Client s use for the purpose for which it is intended in accordance with the agreed scope of work. Boffa Miskell does not accept any liability or responsibility in relation to the use of this report contrary to the above, or to any person other than the Client. Any use or reliance by a third party is at that party's own risk. Where information has been supplied by the Client or obtained from other external sources, it has been assumed that it is accurate, without independent verification, unless otherwise indicated. No liability or responsibility is accepted by Boffa Miskell Limited for any errors or omissions to the extent that they arise from inaccurate information provided by the Client or any external source. Template revision: File ref: A08274_Ecological_Assessment_Report.docx

3 CONTENTS Executive Summary Introduction Location and General Description Development Principles and Design Assessment Purpose and Scope Habitat Values Site Context Terrestrial Flora Waterways Water Quality Standards for Water Quality Structure Plan Area Waterways Receiving Waterways Discussion Sediment Quality Methods Results Discussion Macroinvertebrate Community Assessment Methods Results Discussion Fish Methods Results Fish Records Discussion Avifauna & Bats Herpetofauna Summary of Ecological Values 24 A08274I_Ecological_Assessment_DRAFT_Report_V5_ _LC.docx

4 11.1 Assessment of Ecological Effects Earthworks Stormwater Discharges Summary of Assessment of Ecological Effects Conclusion References 30 Appendices Appendix 1 Figures Appendix 2 Water and Sediment Analysis Reports Appendix 3 Aquatic Macroinvertebrate Results RUAKURA STRUCTURE PLAN AREA Assessment of Ecological Values to inform an Integrated Catchment Management Plan

5 Executive Summary The Ruakura area (known within the Local Government Boundary Reorganisation Scheme as R1 ) comprises a large area of land immediately to the east of the current urban extent of Hamilton City. Within the R1 area, a Structure Plan has been developed and is now included in the Proposed Hamilton City District Plan. Under the provisions of the Structure Plan, the area will be progressively developed primarily for industrial and residential land uses. Land development will require bulk earthworks that will remove most of the existing vegetation and waterways, and result in a change in the nature and volume of stormwater discharges from the site. The purpose of this ecological assessment is: to evaluate existing terrestrial and aquatic ecological values, water and sediment quality within the Ruakura Structure Plan area, and to assess the potential effects of urban development within the Structure Plan area and stormwater discharges relative to the existing catchment characteristics downstream of the Structure Plan area. Accordingly, this assessment is based on baseline field surveys of the ecological values present and existing information on indigenous fauna. It will be used to inform and provide direction for the Integrated Catchment Management Plan (ICMP) (Harrison Grierson & Boffa Miskell 2012). The land within the Ruakura Structure Plan area has the following identified characteristics: Existing vegetation consists mainly of pasture and shade trees, with limited habitat values for indigenous fauna. The waterways are predominantly artificial drains with poor water and habitat quality that provide poor conditions for fish and aquatic macroinvertebrates. Two modified tributary streams within the Structure Plan area have poor water quality but habitat quality is better. It is likely that some water quality parameters approach or exceed the tolerance of all but the hardiest aquatic species for a large part of the year. Sediment quality in waterways is generally suitable for aquatic organisms although some locations have elevated concentrations of contaminants. The waterways provide habitat for giant kokopu, shortfin eels and black mudfish although the size of the populations supported are yet to be established. It is unlikely that the Ruakura Structure Plan area provides habitat of value to bats, native birds, frogs or lizards. Downstream of the Structure Plan area, two tributary streams provide moderate ecological values and marginally better water quality. After fieldwork, baseline analysis and assessment, the following conclusions have been reached: The main potential adverse effects of the proposed development will be removal of waterways as a result of earthworks, changes in water and sediment quality, and changes to the extent of flooding and erosion and scour in downstream waterways. The significance of the ecological effect of drain removal is low. The significance of the ecological effect of the removal of the modified tributary streams is medium. This 1

6 ecological effect is considered to be adequately mitigated by the construction of the proposed stormwater swale network that will provide at least equivalent, and likely enhanced, habitat compared to that removed. The potential significance of the drains as a habitat for black mudfish is yet to be established, and requires further investigation. The significance of the ecological effect of stormwater discharges creating an altered flood regime in downstream waterways is very low. The significance of the ecological effect of stormwater discharges creating changes to erosion and scour conditions in downstream waterways is low to very low. Although not required as mitigation, progressive riparian planting in the gullies of tributary streams downstream of the Structure Plan area would contribute to enhanced bank stability. Beneficial changes arising from the development include a likely improvement in the water quality of stormwater discharges from the Structure Plan area as a result of the change in land use and the installation of stormwater treatment systems. The effect of stormwater discharge on sediment quality is likely to be negligible. 2

7 1.0 Introduction 1.1 Location and General Description Within the ICMP catchment area, the Ruakura Structure Plan area 1 comprises approximately 822 hectares situated to the east of Hamilton City, approximately 2.7 kilometres from the central business district (see Figure 1, Appendix 1). The Structure Plan area is proposed for urban development with residential land use in the northern portion, and industrial and commercial land uses through most of the central area. The existing rural-residential land use in the southern portion will be retained. Within the Structure Plan area, the landholdings consist of properties owned by: Chedworth Park Ltd in the northern portion; Tainui Group Holdings Ltd through most of the central portion; a cluster of private rural-residential landowners between Percival and Ryburn Roads; and A cluster of private rural-residential landowners on either side of Morrinsville Road (SH26). This report pertains to that part of the Structure Plan area proposed for urban development, which is an area of approximately 700 hectares. Most of the area is alluvial plains of the Waikato River which would originally have supported indigenous forest (Cornes et al. 2012). Historical maps show that the central and eastern portions of the Structure Plan area were part of a large wetland (Boffa Miskell 2010). The topography indicates that this area may also have included a small watercourse. By the mid 1900s, the wetland had been drained to create farmland (Boffa Miskell 2010), and the vegetative cover changed from predominantly alluvial secondary native vegetation to exotic pasture (Nicholls 2002). Existing urban development within the Structure Plan area is primarily situated at the Ruakura Agricultural Research Centre and Waikato Innovation Park. The farmland to the north and south, and rural-residential properties to the east, make up the balance of landuse types. There are few existing residential dwellings within the Structure Plan area. Vegetation is dominated by exotic pasture with shelterbelts and shade trees. To the south, the land uses are dominated by residential and rural-residential properties. To the west is the urban area of Hamilton City. 1.2 Development Principles and Design The ICMP and the provisions of the Proposed Hamilton City District Plan will direct and guide development of the Structure Plan area. There are two key activities associated with the urbanisation of the Structure Plan area that will affect ecological values at Ruakura, namely earthworks for land development and the generation of stormwater as a result of urbanisation. 1 As defined in the proposed Hamilton City Council Proposed District Plan

8 1.2.1 Land Development The ICMP and Ruakura Estate Environmental Framework (Boffa Miskell 2011) set out principles of land development which include objectives relating to the protection and enhancement of ecological values, and the provision of ecological restoration through design. The proposed development involves the creation of building platforms, roads, and the installation of infrastructure, particularly the stormwater network. Major excavation is likely to be required to remove unsuitable materials such as peat from areas where ground stability is important. The earthworks required necessitate the removal of vegetation, temporary stockpiling of topsoil and loss of waterways. Although most existing waterways within the Structure Plan area will be removed, they will be replaced with a network of open planted swales and ponds in addition to piped stormwater infrastructure. On retained waterways, and on the created swales and ponds, riparian margins will be managed for values including biodiversity and natural character Stormwater Discharges The quality, volume and flow rate of stormwater discharged from the urbanised areas will be different to the existing stormwater characteristics. Currently, the catchments are dominated by pervious pasture with small areas of less pervious farm tracks and impervious hardstands, buildings and roads. The current impervious area of the Structure Plan area is approximately 7.5%. After development, the amount of impervious area is likely to be around 66%. As a result, a greater volume of stormwater will be generated. It is expected that the change in land use from predominantly agricultural to a mix of residential, commercial and industrial land will also change the stormwater contaminant profile. The existing contaminants are primarily nutrients, sediment and bacterial pathogens. The future contaminants will be primarily sediment, petroleum hydrocarbons, and metals. However this will vary depending on the predominant future land use. For instance, nutrients and bacterial pathogens will be generated in future residential areas at lower rates than are currently experienced with agricultural land use but at higher rates than would be expected from future commercial and industrial areas. Stormwater treatment design (see Figure 2, Appendix 1) has been undertaken based on the principles of Low Impact Design, incorporating a treatment train approach. The stormwater devices proposed are intended to manage the effects of stormwater discharges in a sustainable and appropriate manner, with a particular emphasis on mitigating the effects on flows and ecological values of the waterways downstream (Harrison Grierson & Boffa Miskell 2012). The stormwater treatment system will also provide the additional benefits of habitat for indigenous wetland biota, biological diversity enhancement, enhancement of visual amenity, and provision of recreational and pedestrian linkages (Boffa Miskell 2011). The proposed design of the stormwater treatment system for the Structure Plan area incorporates: On-site interception and primary treatment of stormwater from individual properties on commercial and industrial land, prior to discharge to the stormwater network. Off-site treatment of stormwater from residential land within the stormwater network. Diverting all stormwater through a series of stormwater treatment devices including swales, ponds and wetlands to attenuate flow and remove a large proportion of contaminants. Intensive treatment of stormwater from particular land uses generating high contaminant loads. 4

9 2.1 Assessment Purpose and Scope The purpose of this assessment is to: Evaluate existing terrestrial and aquatic ecological values within the Structure Plan area, Evaluate existing water quality of watercourses within the Structure Plan area and in the waterways downstream, and Assess the potential effects of land development and stormwater discharges on ecological values and water quality. It is important to note that the urbanisation of the Ruakura Structure Plan area will occur over a timeframe of decades. However, this assessment takes a precautionary approach and has been completed on the basis of the anticipated effects of a fully executed development. As set out in Table 1, this assessment has been based on two main bodies of work, namely: Baseline surveys of riparian and aquatic habitat, biota, sediment quality and water quality values present in the waterways on and downstream of the Structure Plan area; and Evaluations of existing information relating to fauna values (birds, bats, and herpetofauna) within the Structure Plan area and surrounding areas. Table 1: Data collection and methodology Parameter Methodology Habitat values Water contaminants Sediment contaminants Aquatic macroinvertebrate fauna Fish fauna Avifauna Herpetofauna Stream habitat assessment (instream and riparian, qualitative and quantitative (SEV) assessments). Water samples analysed for ph, suspended sediment, turbidity, copper, iron, lead, zinc, nitrogen, phosphorus, carbonaceous biochemical oxygen demand, faecal bacteria and petroleum hydrocarbons. Sediment samples analysed for arsenic, cadmium, chromium, copper, lead, nickel, and zinc. Aquatic macroinvertebrate samples collected using Protocols C2 and C4 (MfE, 2001). Evaluation of Freshwater Fish Database records. Fish survey. Evaluation of Ornithological Society records and technical papers. Evaluation of NZ Herpetofauna Database records and technical papers. 5

10 3.0 Habitat Values 3.1 Site Context Ruakura is located within the Waikato Ecological Region and the Hamilton Ecological District. The indigenous vegetation of the Hamilton Ecological District is severely depleted, with only 1.6% of the original native vegetation remaining and at least 20% of its indigenous flora threatened or extinct (Clarkson & McQueen 2004). Almost all of the original alluvial floodplain vegetation and swamps of the Waikato lowlands have been cleared and drained for farming (Nicholls, 2002). Within Hamilton City, there is less than 20 hectares of high quality indigenous habitat remaining (Clarkson & McQueen, 2004). The Lands Environments of New Zealand (LENZ) database classifies most of the site as Environment A5.3 which is comprised of poorly-drained peat soils of low to very low fertility. Small areas to the north-west and south of the site are classified as Environment 7.2 which is very gently undulating hills with imperfectly drained soils of low fertility, comprised of volcanic soils, alluvium and peat. These classifications are shown on Figure 3 in Appendix Terrestrial Flora Vegetation The terrestrial flora at Ruakura mirrors the situation in the surrounding areas. Historic vegetation cover was secondary succession alluvial vegetation (Nicholls 2002), most likely kahikatea swamp forest, with mixed coniferbroadleaf forest on higher ground (Clarkson et al. 2007, Cornes et al. 2012). Some areas of peat bog vegetation (Clarkson et al., 2007) and lowland swamp vegetation may also have occurred, depending upon the type, depth and drainage properties of the soils present. Today, the area is almost entirely vegetated in exotic pasture grasses (see Plate 1). Larger trees and shrubs are limited to exotic species planted as shelterbelts, or for amenity and animal welfare purposes (livestock shade). Adjacent to waterways there is typically limited riparian vegetation (see Plate 1). Where drain margins are not regularly maintained, this is Plate 1: Typical vegetation and waterway within the Ruakura Structure Plan area. 6

11 comprised of rank grass, herbaceous weeds and shrub weeds such as Chinese privet, gorse and blackberry. Native plants are very occasionally present, including karamu, mapou, silver fern and mamaku 2 which have established naturally. The most recent vegetation survey of Hamilton City did not identify any key ecological sites of significance within the Structure Plan area (Cornes et al. 2012) Significant Vegetation Figure 4 (Appendix 1) shows sites of significant vegetation, most of which are small isolated features within the urban area on the alluvial plains, including Claudelands Bush, Southwell Bush, Caldwell Native Bush, Waikato University kahikatea, and Hillcrest kahikatea (Cornes et al. 2012). The Kirikiriroa Stream gully to the north also has two sites not directly connected with the gullies draining Ruakura, namely Kirikiriroa Gully Arm I and II adjacent to Gordonton Road. These sites have limited potential for creating connections with Ruakura. There are four key ecological sites located in gullies close to the Structure Plan area that have potential to benefit from connectivity with the proposed stormwater treatment system and amenity plantings within the Structure Plan area. The main part of the Kirikiriroa Stream gully has two sites, Kirikiriroa Gully Chartwell and Kirikiriroa Gully Mangaiti. These are both large well developed sites with mixed native scrubland/shrubland and large wetlands (Cornes et al. 2012). These sites are linked to the Waikato River and provide a habitat and corridor for native flora and fauna. The Mangaonua Stream gully to the south has two sites, Mangaonua Gully Chelmsford and Mangaonua Gully Silverdale. These are both large sites with a diverse indigenous understorey located on the tributary of the Mangaonua Stream discharging from Ruakura (Cornes et al. 2012). In total, this gully system has 11 key ecological sites totalling 9.7 hectares, linked to key sites such as Hammond Bush and the Waikato River, and is considered to be an important habitat and corridor for native flora and fauna (Cornes et al. 2012). Of the identified sites, three (Claudelands Bush, Southwell Bush, and Hillcrest kahikatea) are recognised in the HCC Operative District Plan as Significant Vegetation Sites in the Environment Protection Overlay (as shown in Figure 4 in Appendix 1) based on an ecological rank of 1 (very high ecological value) in Cornes et al. (2012). Kirikiriroa Gully Chartwell, Kirikiriroa Gully Mangaiti, and Mangaonua Gully Chelmsford have an ecological rank of 2 (high ecological value) and Mangaonua Gully Silverdale has an ecological rank of 3 (moderate ecological value) (Cornes et al. 2012). 3.3 Waterways There are numerous waterways within and adjacent to the Ruakura Structure Plan area (see Figure 5 in Appendix 1). These consist of natural watercourses, modified watercourses, private artificial waterways (drains) and artificial waterways managed by Waikato Regional Council (WRC). 2 Coprosma robusta, Myrsine australis, Cyathea dealbata and Cyathea medullaris. 7

12 3.3.1 Structure Plan Area Waterways Plate 2: Example of a regularly maintained drain. Plate 3: Example of a drain maintained less regularly. All the waterways within the Structure Plan area have been surveyed. Most are channelised farm drains (generally artificial watercourses created to drain historic wetlands or land with high groundwater/springs) with near uniform depth and velocity. The drains are cleaned out to maintain drainage for the adjacent farmland, but the frequency of drain excavation appears to vary such that some drains appear to be excavated regularly while others may not have been excavated in years. Regularly excavated drains provide poor habitat for fish and aquatic invertebrates, with low habitat diversity, and minimal stable habitat, shade and riparian vegetation (see Plate 2). Drains excavated less often generally have more riparian and instream vegetation and shade, and therefore generally Plate 4: Example of an ephemeral dish channel. 8

13 provide more suitable habitat for fish and aquatic invertebrates, though are still considered to be marginal habitats (see Plate 3). In addition to the drains, there are ephemeral dish channels running through many paddocks to facilitate the rapid drainage of surface water from pasture after rainfall (see Plate 4). These channels are typically vegetated with pasture, though some contain rushes and herbaceous weeds such as willow weed. As shown in Figure 5 (Appendix 1), there are two streams located within the Structure Plan area, a tributary of the Mangaonua Stream and a tributary of the Kirikiriroa Stream (see Plate 5). These are modified tributaries but have natural characteristics such as meandering channels, variability in water depth and flow rate, some stable habitat, shade and riparian vegetation. These waterways provide suboptimal and marginal habitat respectively for fish and aquatic invertebrates. Riparian vegetation varies across the Structure Plan area and includes grazed or sprayed short grass, ungrazed rank grass and weeds, shelterbelt/shade trees, and moderate Plate5: Modified Kirikiriroa Stream tributary. to dense cover of exotic trees/shrubs/vines. The effectiveness of the riparian vegetation in providing habitat and shade to the adjacent waterways depends on the height and density of the vegetation and the orientation of the waterway. However, only a very small area of these waterways currently benefits from tall dense riparian vegetation. Many of the waterways are fenced to exclude stock, but most of the ephemeral dish channels running through paddocks are not fenced. Within the waterways, there are a number of barriers to the passage of non-climbing fish species (see also Section 7.0), namely perched culverts and piped drains. However, given that the future development of the Structure Plan area will result in the removal of the waterways, an analysis of these barriers was not undertaken. None of the waterways within the Ruakura Structure Plan area has been classified under the WRC Regional Plan Water Management Class Maps, and therefore default to Waikato Surface Water class Receiving Waterways Waterways downstream of the Ruakura Structure Plan area that will receive future stormwater discharges from the Structure Plan area have been surveyed. 9

14 To the northwest and south respectively, the Kirikiriroa and Mangaonua Streams are largely natural waterways that flow through extensive gully systems and discharge into the Waikato River. A tributary of the Mangaonua Stream flows from the southern boundary of the Structure Plan area through a deeply incised gully and discharges into the main stem of the Mangaonua Stream via a culvert beneath Morrinsville Road. Two tributaries of the Kirikiriroa Stream flow from the northwestern boundary of the Structure Plan area beneath Gordonton Road into a gully system that discharges into the main stem of the Kirikiriroa Stream via a culvert under Wairere Drive. These streams provide a conduit for freshwater fish and aquatic invertebrates to migrate upstream to the waterways of the Structure Plan area. There are likely to be physical obstacles to fish passage, particularly pipes and culverts that are impassable to non-climbing species. For instance, one of the pipes connecting the Mangaonua Stream tributary with the Structure Plan area drains is approximately 180m long which exceeds the distance that most fish species will pass through. A second pipe is likely to be at a gradient that only eels could traverse. In general, the Mangaonua and Kirikiriroa Stream tributaries provide marginal to suboptimal habitat for fish and aquatic invertebrates, with moderate habitat diversity, habitat stability, shade and riparian vegetation. To the west of the Structure Plan area, farm drains discharge into the HCC reticulated stormwater system, prior to discharging into tributaries of or directly into the Waikato River. The length of the reticulated network is likely to preclude the passage of all fish. To the east of the Structure Plan area, farm drains discharge into WRC drainage board drain networks within the ICMP area. East of Powells Road and Percival Road, the drains discharge into the network known as the Brinkworth drain. The presence of obstacles to fish passage in these networks is not known. However, the relatively flat gradient is likely to allow fish passage while drain cleaning and spraying of channel vegetation will limit populations. As for drains within the Structure Plan area, these drains provide poor habitat for fish and aquatic macroinvertebrates. Only the Mangaonua Stream tributary has been classified under the WRC Regional Plan Water Management Class Maps as Waikato Surface Water. All other unclassified waterways default to Waikato Surface Water class. 4.0 Water Quality 4.1 Standards for Water Quality The Waikato Regional Plan rules for stormwater discharges refer to the ANZECC 2000 Australian and New Zealand Guidelines for Fresh and Marine Waters Quality as one of the standards against which hazardous substances in stormwater are to be assessed in order to achieve the conditions associated with the relevant rule. HCC was granted a comprehensive consent from WRC for the discharge of stormwater from its urban area. The comprehensive consent conditions refer to the USEPA (United States 10

15 Environmental Protection Agency) National Recommended Water Quality Criteria as the standard which the concentration of hazardous substances in discharges are required to meet. Based on correspondence with WRC staff, we understand that the USEPA criteria are considered more appropriate than the locally derived ANZECC criteria because they reference the dissolved fraction of stormwater contaminants (specifically metals such as copper, lead and zinc) and provide standards for acute (short-term) exposure as well as chronic (long-term) exposure. The dissolved fraction of contaminants is considered to be more relevant to the toxicity effects experienced by water column-dwelling biota compared to total concentrations which includes the particulate fraction. Acute exposure is considered to be more relevant to the intermittent nature of stormwater discharges. While it is likely that future discharge consents granted for the development at Ruakura will reference the USEPA criteria, it is appropriate to assess existing water quality against the ANZECC guidelines when establishing the quality of the existing environment. 4.2 Structure Plan Area Waterways The existing water quality of the waterways within the Structure Plan area waterways has been assessed as a baseline against which to evaluate changes that may occur from land development within this area of the catchment and associated stormwater discharges Methods Water samples were collected from the main waterways contributing to the stormwater currently discharging from the Structure Plan area (see Figure 6). The grab samples (and accompanying chain of custody documentation) were chilled and sent to Hill Laboratories for analysis Results A results summary is presented below in Table 2 and laboratory reports are provided in Appendix 2. In Table 2, the results are compared against the guideline values noted in the footnotes. Results in bold and shaded exceed the guideline value. Results in bold only are those values that are elevated but for which there is no guideline value. Table 2: Water Sample Analysis On-Site Waterways Units Ruakura Road drain Tramway Road drain Reeves Close drain Kirikiriroa Stm tributary at Wairere Dr Percival Road drain Sep 2012 Oct 2012 Oct 2012 Sep 2012 Sep 2012 Guideline Values Turbidity NTU ph ph Units Total Suspended Solids g/m < 3 - Total Copper g/m Total Iron g/m Total Lead g/m Total Zinc g/m Australian and New Zealand Environment and Conservation Council; Agriculture and Resource Management Council of Australia and New Zealand Australian and New Zealand Guidelines for Fresh and Marine Waters Quality. Trigger values for aquatic ecosystem protection at 90% protection of species. 11

16 Table 2: Water Sample Analysis On-Site Waterways Units Ruakura Road drain Tramway Road drain Reeves Close drain Kirikiriroa Stm tributary at Wairere Dr Percival Road drain Guideline Values Total Nitrogen g/m Nitrate-N + Nitrite-N g/m Total Kjeldahl Nitrogen g/m Dissolved Reactive Phosphorus g/m Total Phosphorus g/m Carbonaceous Biochemical Oxygen < 2 < 2 < 2 < 2 < 2 - Demand (CBOD5) g O2/m 3 Escherichia coli cfu/100ml , Total Petroleum Hydrocarbons C7-C36 g/m 3 <0.7 <0.7 <0.7 <0.7 <0.7 - There is no guideline value for turbidity. However, the ANZECC Guidelines refer to research relating to avoidance behaviour in banded kokopu at turbidity of 20NTU. Since this species is present in the wider catchment, this value has been used for information purposes as an indicator of potential impacts from turbidity and suspended sediments. Turbidity exceeded 20NTU at 3 of the 5 sites. However, this does not correspond with elevated suspended solids concentrations indicating water staining by other sources, namely peat and iron flocs. As expected in waterways draining peat soils, ph tends to be acidic at some sites. As expected based on the orange staining and iron flocs observed throughout the Structure Plan area, concentrations of iron are high at most sites. Although not analysed, it is expected that concentrations of manganese would be similarly elevated. There is no guideline value for total iron, but at these concentrations iron and manganese oxidation processes are likely to reduce the oxygen saturation of water. The concentration of copper exceeds the ANZECC guideline in the Percival Road drain. The drain receives road runoff but traffic volumes are likely to be low. The copper is more likely to be from an agricultural or groundwater source. Concentrations of copper approach but do not exceed the guideline at the Tramway Road and Reeves Close drains, although these drains discharge into the HCC reticulated network. There is little or no urban stormwater discharged into these drains so the copper is more likely to be from an agricultural or groundwater source. The concentration of zinc exceeds the ANZECC guideline at all sites except the Kirikiriroa Stream tributary upstream of Wairere Drive. Because there is little or no urban stormwater discharged into these drains, the zinc is likely to be from an agricultural or groundwater source. Elevated concentrations of nitrogen and phosphorus, and high numbers of microbial pathogens, are ubiquitous across the Structure Plan area waterways. Nitrogen and phosphorus are present at all sites at concentrations far exceeding that required to limit algal growths based on the Ministry for the Environment water quality guidelines. E. coli is present at levels that preclude use of the water for contact recreation or livestock watering. CBOD was below the detection limit at all sites. However, given the current agricultural land uses, it is likely that CBOD fluctuates in response to inputs of organic matter. Petroleum hydrocarbons were not detected. 4 Ministry for the Environment, Water Quality Guidelines No. 1: Guidelines for the Control of Undesirable Biological Growths in Water. 5 Australian and New Zealand Environment and Conservation Council; Agriculture and Resource Management Council of Australia and New Zealand Australian and New Zealand Guidelines for Fresh and Marine Waters Quality. Livestock drinking water guidelines Faecal coliforms. 12

17 Although not measured in these samples, observations of the beds of the waterways indicate that the watercourses regularly experience spikes of elevated suspended sediment. Observations also indicate that summer water temperatures are likely to regularly exceed the thermal tolerances of many fish and macroinvertebrate species on the parts of the drain that are not shaded by banks or vegetation, and where flows are low or ephemeral. 4.3 Receiving Waterways The existing water quality of waterways that will receive future stormwater discharges from the Structure Plan area was assessed. The results are interpreted as an indication of the state of the receiving environment against which to evaluate effects that may occur as a result of the future discharges Methods Grab water samples were collected from the Mangaonua Stream tributary and Brinkworth drain into which stormwater is expected to discharge when development occurs (see Figure 6). The samples were transported directly to Hill Laboratories for analysis with chain of custody documentation. Monitoring results for the period January 2008 to December 2012 were obtained from WRC for the two relevant water quality monitoring sites, namely the Mangaonua Stream at Hoeka Road and the Kirikiriroa Stream at Tauhara Drive Results The WRC Mangaonua Stream monitoring site at Hoeka Road is approximately 6km upstream of the confluence of the Mangaonua Stream tributary with the main stem of the Mangaonua Stream. Water quality records from this site should be interpreted with caution in relation the state of the receiving environment since its source catchments are almost entirely agricultural. The tributary of the Mangaonua Stream that will receive future stormwater discharges from the Structure Plan area currently receives stormwater from a catchment with agricultural, commercial (education) and residential land uses. Water quality in this tributary can therefore be expected to be quite different than that measured at Hoeka Road, and more representative of the state of the receiving environment at the proposed point of stormwater discharge. A summary of WRC monitoring results is presented below in Table 3 and Table 4 contains Boffa Miskell monitoring results. Full results are provided in Appendix 2. In Tables 3 and 4, the results are compared against the guideline values noted in the footnotes. Results in bold and shaded exceed the guideline value. Results in bold only are those values that are elevated but for which there is no guideline value. Table 3: WRC Water Sample Analysis Off-Site Waterways Kirikiriroa Stm, Tauhara Dr Jan Dec 2012, n = 60 Mangaonua Stm, Hoeka Rd Jan Dec 2012, n = 60 Units Ave Max Min Ave Max Min Dissolved Oxygen % Turbidity NTU Guideline Values ph ph Units Australian and New Zealand Environment and Conservation Council; Agriculture and Resource Management Council of Australia and New Zealand Australian and New Zealand Guidelines for Fresh and Marine Waters Quality. Trigger values for aquatic ecosystem protection at 90% protection of species. 13

18 Table 3: WRC Water Sample Analysis Units Kirikiriroa Stm, Tauhara Dr Jan Dec 2012, n = 60 Mangaonua Stm, Hoeka Rd Jan Dec 2012, n = 60 Total Suspended Solids g/m 3 NR NR NR NR NR NR - Guideline Values Total Copper g/m 3 NR NR NR NR NR NR Total Iron g/m 3 NR NR NR NR NR NR - Total Lead g/m 3 NR NR NR NR NR NR Total Zinc g/m Total Nitrogen g/m 3 NR NR NR NR NR NR Nitrate-N + Nitrite-N g/m Total Kjeldahl Nitrogen (TKN) g/m Dissolved Reactive Phosphorus g/m Total Phosphorus g/m Carbonaceous Biochemical Oxygen Demand (CBOD5) g O2/m 3 NR NR NR NR NR NR - cfu / Escherichia coli 100mL 1,066 3, ,020 11, Total Petroleum Hydrocarbons NR NR NR NR NR NR C7-C36 g/m 3 - NR: Analyte not recorded by WRC as part of regular monitoring programme. Table 4: Water Sample Analysis Off-Site Waterways Mangaonua Stm Tributary, Morrinsville Rd Brinkworth Drain Greenhill Rd drain Units Jan 2013 Sep 2012 Jan 2013 Sep 2012 Turbidity NTU Guideline Values ph ph Units Total Suspended Solids g/m Total Copper g/m < Total Iron g/m Total Lead g/m < < Total Zinc g/m Total Nitrogen g/m Nitrate-N + Nitrite-N g/m Total Kjeldahl Nitrogen (TKN) g/m Dissolved Reactive Phosphorus g/m <0.004 < Total Phosphorus g/m Carbonaceous Biochemical Oxygen Demand (CBOD5) g O2/m3 < 2 <2 < 2 2 cfu / Escherichia coli 100mL 1, Total Petroleum Hydrocarbons C7-C36 g/m 3 <0.7 <0.7 <0.7 <0.7-7 Ministry for the Environment, Water Quality Guidelines No. 1: Guidelines for the Control of Undesirable Biological Growths in Water. 8 Australian and New Zealand Environment and Conservation Council; Agriculture and Resource Management Council of Australia and New Zealand Australian and New Zealand Guidelines for Fresh and Marine Waters Quality. Livestock drinking water guidelines Faecal coliforms. 9 Australian and New Zealand Environment and Conservation Council; Agriculture and Resource Management Council of Australia and New Zealand Australian and New Zealand Guidelines for Fresh and Marine Waters Quality. Trigger values for aquatic ecosystem protection at 90% protection of species. 10 Ministry for the Environment, Water Quality Guidelines No. 1: Guidelines for the Control of Undesirable Biological Growths in Water. 11 Australian and New Zealand Environment and Conservation Council; Agriculture and Resource Management Council of Australia and New Zealand Australian and New Zealand Guidelines for Fresh and Marine Waters Quality. Livestock drinking water guidelines Faecal coliforms. 14

19 Turbidity exceeded 20NTU at 4 of the 5 sites. At the Boffa Miskell sites, except at the Brinkworth drain, elevated turbidity does not correspond with elevated suspended solids concentrations indicating water staining by other sources, namely peat and iron flocs. The Brinkworth drain had high turbidity and suspended solids at the time of sampling. As expected in waterways draining peat soils, ph was acidic at some sites. Although there are acidic waters contributing to the Mangaonua Stream tributary, ph is normalised at the sampling point by dilution from the Mangaonua Stream tributary west branch that takes large volumes of water from the Waikato University catchment. Both the WRC sites had neutral ph. As expected based on the orange staining and iron flocs observed, concentrations of iron are very high at the sites surveyed by Boffa Miskell. Although not analysed, it is expected that concentrations of manganese would be similarly elevated. Iron and manganese oxidation processes are likely to reduce the oxygen saturation of water. The concentration of copper does not exceed the ANZECC guideline at any of the sites surveyed by Boffa Miskell, but the concentration of zinc exceeds the ANZECC guideline at 3 of the 5 sites. Elevated concentrations of nitrogen and phosphorus, and high numbers of microbial pathogens, are ubiquitous throughout the waterways. Nitrogen and phosphorus are present at all sites at concentrations far exceeding that required to limit algal growths based on the Ministry for the Environment water quality guidelines. E. coli is present at all sites at levels that preclude use of the water for contact recreation or livestock watering. CBOD was at the detection limit at the Greenhill Road drain, but was below the detection limit at all other Boffa Miskell sites. However, given the current agricultural land use dominating these catchments, it is likely that CBOD fluctuates in response to inputs of organic matter. Petroleum hydrocarbons were not detected at any Boffa Miskell sites. Observations of the beds of the waterways indicate that many of these watercourses regularly experiences spikes of elevated suspended sediment. 4.4 Discussion In general, existing waterways are likely to receive ongoing inputs of turbidity, suspended sediment, faecal bacteria (from livestock and waterfowl) and nutrients resulting in low clarity, frequent algal blooms, and water unsuitable for human contact or livestock consumption. In many of these waterways, low dissolved oxygen concentrations will approach or exceed the tolerance of all but the hardiest aquatic species for a large part of the year as a result of: algal growths, elevated iron concentrations, high proportion of base flow sourced from groundwater, low or no summer flow; and/or elevated summer temperatures. For waterways within the Structure Plan area, when combined with naturally low ph from peat soils and high concentrations of metals (iron, zinc and copper), this water quality is very poor and provides harsh conditions suitable for only the most tolerant of aquatic organisms. The riparian vegetation that could mitigate some of these conditions is largely absent. This assessment is supported by aquatic macroinvertebrate samples showing MCI and QMCI scores which indicate high levels of disturbance and/or probable severe pollution (see Section 6.0). 15

20 Conditions are better in the waterways outside the Structure Plan due to neutral ph, higher flows and lower concentrations of metals. Riparian vegetation is also more substantial on most of the waterways outside the Structure Plan area, which will contribute to lower water temperatures, lower algal growths and improved habitat. 5.0 Sediment Quality The existing quality of sediment in waterways within the Ruakura Structure Plan area and receiving waterways downstream was assessed as a baseline against which to evaluate changes that may occur as a result of land development and future stormwater discharges. 5.1 Methods Sediment samples were collected from the bed of the main waterways into which stormwater is expected to discharge when development occurs. The samples were chilled and sent to Hill Laboratories for analysis under chain of custody documentation. 5.2 Results A results summary is presented below in Table 5 and full laboratory reports are provided in Appendix 2. In Table 5, the results are compared against the ANZECC 2000 Interim Sediment Quality Guidelines (ISQG) as noted in the footnotes. Results in bold and shaded equal or exceed the guideline value. Table 5: Sediment Sample Analysis Units Ruakura Road drain Tramway Road drain Reeves Close drain Kirikiriroa Stm tributary at Wairere Dr Greenhill Road drain Percival Road drain Brinkworth Drain Sep 2012 Oct 2012 Oct 2012 Sep 2012 Sep 2012 Sep 2012 Jan 2013 ISQG - Low Guideline Values 12 Total Recoverable Iron mg/kg 16,400 7,600 46,000 36,000 24,000 7, ,000 - Total Recoverable Arsenic mg/kg Total Recoverable Cadmium mg/kg 0.24 < 0.10 < Total Recoverable Chromium mg/kg Total Recoverable Copper mg/kg Total Recoverable Lead mg/kg Total Recoverable Nickel mg/kg 8 < 2 < Total Recoverable Zinc mg/kg Except for the Ruakura Road drain and the Brinkworth Drain, the concentration of metals in sediment is below the ISQG-Low trigger concentrations indicating a low risk of these contaminants causing biological disturbance to benthic fauna. In the Ruakura Road drain, the 12 Australian and New Zealand Environment and Conservation Council; Agriculture and Resource Management Council of Australia and New Zealand Australian and New Zealand Guidelines for Fresh and Marine Waters Quality. Interim sediment quality guidelines. 16

21 concentrations of copper and lead in sediment exceed the ISQG-Low concentration indicating the potential for adverse effects on benthic fauna. The concentration of zinc exceeds the ISQG- Low and -High concentrations indicating likely adverse effects on benthic fauna. In the Brinkworth Drain, the concentration of arsenic in sediment exceeds the ISQG-Low concentration indicating the potential for adverse effects on benthic fauna. 5.3 Discussion The Ruakura Road drain consists of a short open section of drain that discharges into the HCC reticulated network. The value of the drain for benthic fauna is likely to be very limited. In the Brinkworth Drain, the toxicity of arsenic to benthic fauna will depend on the conditions in the sediment contributing to bioavailability, including the extremely high concentration of iron. Except for these two sites, sediment quality in these waterways is typical of agricultural watercourses with most metals detected but at concentrations that are generally suitable for aquatic benthic fauna. 6.0 Macroinvertebrate Community Assessment 6.1 Methods Aquatic macroinvertebrates were collected using a 500 micron net following Protocol C1 and C2 (Ministry for the Environment 2001), preserved in ethanol and analysed according to Protocol P1: coded abundance. The hard-bottom or soft-bottom Macroinvertebrate Community Index (MCI or MCIsb) and Semi- Quantitative MCI (SQMCI) was calculated for each sample (Stark & Maxted 2007). Stream 1B was the only hard-bottom stream within the Structure Plan area. Species richness and number of EPT 13 taxa were also calculated. Table 6: Macroinvertebrate Sample Analysis Taxonomic richness 6.2 Results The full macroinvertebrate analysis report is provided in Appendix 3 and the summary table is shown below. Mangaonua Stm tributary west U/S Nevada Rd Mangaonua Stm tributary west D/S Silverdale Rd Mangaonua Stream tributary east Railway drain at Ryburn Rd Percival Road drain Reeves Close drain Greenhill Road drain Kirikiriroa Stream tributary at Wairere Dr No. of EPT Taxa MCI * SQMCI* Tramway Road drain 13 EPT: Ephemeroptera (mayflies), Plecoptera (stoneflies) and Trichoptera (caddisflies), the most sensitive aquatic macroinvertebrate species indicative of good water quality and habitat. 17

22 *Site 1B Mangaonua Stream tributary west downstream of Silverdale Road uses hard-bottom indices. All other sites are soft-bottomed. Macroinvertebrate diversity was low at all sites. A total of 28 macroinvertebrate taxa were found across the nine sites surveyed. The highest species richness was 13, found at the Greenhill Road drain and Mangaonua Stream tributary west branch upstream of Nevada Road. The Reeves Close drain had 10 taxa while the other sites had either 7 or 8 taxa present. Oligocheate worms, typically associated in poor water quality, were found at all sites and dominated most samples. Ostracod crustaceans were prevalent at 3 sites and Chironomid midges were recorded at 7 sites. No mayflies or stoneflies were recorded in any of the samples, and only two species of caddisfly were present. Oxyethira, a pollution-tolerant species which feeds on algal growths, was present at 2 sites. Triplectides, a stick caddisfly whose larvae live in slow flowing streams, was recorded at 2 sites. No other sites had EPT taxa recorded. MCI scores ranged from 65 to 99.14, which are low scores indicating poor to fair water and/or habitat quality (Stark & Maxted 2007). Four sites (Mangaonua Stream tributary east branch, Railway drain at Ryburn Road, Percival Road drain and Kirikiriroa Stream tributary at Wairere Drive) scored in the fair quality range. These slightly higher scores are the result of low numbers of taxa with slightly higher MCI scores that were collected in the sample. The SQMCI score takes into account the relative abundance of each taxa in the sample. These results were more consistent, with almost all sites falling into the poor category. Kirikiriroa Stream tributary at Wairere Drive had the highest SQMCI score of 5.36 due to very abundant Tanypodoninae flies and amphipods which raised the score relative to the other sites. Mangaonua Stream tributary west branch downstream of Silverdale Road had the lowest score of 1.64 as a result of the hard bottom sensitivity score for Oligochaete worms being 1, compared with 4 for the soft-bottom sites. This effectively reduces the SQMCI score at site 1B relative to the others. If the soft bottom tolerance score is used for site 1B, the SQMCI increases to 3.58, very similar to the other sites. 6.3 Discussion The MCI /SQMCI scores reflect the habitat and water quality present at the sites. While some of these factors could be improved with changed land use, enhancement of riparian vegetation and treatment of stormwater inputs, some water quality parameters are natural characteristics of the peat-derived groundwaters that comprise a large proportion of the base flow of these waterways. On balance, an improvement in the MCI/SQMCI scores could be expected with stormwater treatment and restoration of the Kirikiriroa Stream tributary site. The scores of the Greenhill Road Drain and the railway drain at Ryburn Rd are likely to be relatively unchanged because habitat values and water quality are unlikely to change sufficiently to influence the aquatic macroinvertebrate community. There is potential for the MCI/SQMCI scores of the future stormwater swales to be higher than in the existing waterways in the medium to long term. This could occur as a result of the proposed riparian/wetland/swale planting providing improved aquatic habitat and improved water quality resulting from land use changes and stormwater treatment. However, it will take some time for these future stormwater swale environments to provide stable habitats for aquatic macroinvertebrate communities to colonise. 18

23 7.0 Fish Table 7: Fish Survey Methods 7.1 Methods Nine waterways were identified as potentially supporting fish populations within or immediately adjacent to the Structure Plan area (Figure 6, Appendix 1). Farm drains that appear to be dry for a large proportion of the year were not surveyed for fish. Mangaonua Stm trib west U/S Nevada Rd Mangaonua Stm trib west D/S Silverdale Rd Mangaonua Stm trib east Railway drain at Ryburn Rd Mangaonua Stm trib D/S Nevada Rd Percival Road drain Reeves Close drain Greenhill Road drain Kirikiriroa Stm tributary at Wairere Dr Tramway Road drain Electric fishing * Fyke nets Box traps D/S = downstream. U/S = upstream. *Downstream of Sites 1A and 1B, outside study area. EFM only required. Where electric fishing was undertaken, an EFM 300 backpack electric fishing machine was used to make one pass moving upstream along a 50m section of stream. Where Fyke nets were used, 4 nets were set overnight. Where box traps were used, 10 box traps, 5 baited and 5 unbaited, were set at each site overnight. All fish caught were identified, measured, and released. Table 8: Fish Survey Results 7.2 Results Fish diversity was low across all sites (Table 8). No fish were captured at 4 sites. In total, only three species were caught, namely shortfin eels (Anguilla australis), giant kokopu (Galaxias argenteus) and black mudfish (Neochanna diversus). The latter two consisted of one individual and both are At Risk species (Allibone et al. 2010). Mangaonua Stm trib west U/S Nevada Rd Mangaonua Stm trib west D/S SilverdaleRd Mangaonua Stm trib east Railway drain at Ryburn Rd Mangaonua Stm trib D/S Nevada Rd Percival Road drain Reeves Close drain Greenhill Road drain Shortfin eel Giant kokopu 1 Black mudfish 1 Kirikiriroa Stm tributary at Wairere Dr No. of species Tramway Road drain 19

24 Plate 6: Immature giant kokopu on Manaonua Stream tributary, west branch, upstream of Nevada Road. 7.3 Fish Records In the Waikato River catchment, 17 native fish species have been recorded (David & Speirs 2010). As shown in Figure 7a and the associated table in Figure 7b (Appendix 1), the NIWA Freshwater Fish Database has 117 records for fish surveys undertaken on watercourses on or hydrologically connected to the Ruakura Structure Plan area 14 with a total of 14 identified species (excluding unidentified eels and galaxias species). Of these, 10 are native species. Fifteen percent of records were either for exotic species (mosquitofish, rudd, koi carp or trout) or had no fish caught. There are 14 records for peat-influenced waterways located on the alluvial plains on or near the Structure Plan area. All other records are located within the gully networks. Six records are located within the Structure Plan area itself, all of which are mudfish. All of the 13 mudfish records (11%) are in the peat-influenced waterways on the alluvial plains. The only other species recorded in these waterways is shortfin eel (1 record). Smelt have been recorded in the Kirikiriroa and Mangaonua Stream catchments close to the Structure Plan area. Inanga and giant kokopu have been recorded only in the Kirikiriroa Stream catchment, although based on the June 2010 survey reported in Section 7.2 above, giant kokopu are also found in the Mangaonua Stream tributaries. Koura and Crans bully have been recorded only in upper Mangaonua Stream tributaries, while common bully has been recorded only in lower Mangaonua Stream reaches. Shortfin and longfin eels are recorded throughout the entire area. 14 Included in the selected records are all surveys undertaken within the Ruakura Structure Plan area waterways and those streams/tributaries that are hydrologically connected to the site, therefore indicating the range of species in the catchment that could potentially inhabit small waterways within the Structure Plan area. 20

25 7.4 Discussion Fish Diversity There are a number of factors to consider when assessing the fish diversity associated with waterways within the Ruakura Structure Plan area. The low recorded diversity may be indicative of the poor aquatic and riparian habitat quality, poor water quality, and the likely presence of significant barriers to fish passage. The drains are likely to experience regular disturbance from excavation, spraying of riparian and channel vegetation, and inputs of sediment, nutrients and metals that adversely affect water and habitat quality for fish. However, most of the waterways within the Structure Plan area naturally experience low ph, high iron concentrations and low dissolved oxygen from peat-derived groundwater. Many of these drains will also dry out over the summer as groundwater levels drop. This combination of factors will naturally limit the number of species that can tolerate these conditions regardless of other habitat and water quality conditions. For instance, inanga, smelt, Crans bully, and giant kokopu are found in the wider catchment but would not be found naturally in waterways experiencing these conditions. Banded kokopu, koura, mudfish and eels could be expected to be found naturally in these conditions. Of these, koura and banded kokopu are not found in waterways within the Structure Plan area. Giant kokopu favour small to medium sized gently flowing streams or wetlands with riparian vegetation (McDowall 2000) and were found in a non-peat influenced tributary of the Mangaonua Stream within the Structure Plan area. Therefore, the low recorded fish diversity is unlikely to be substantially less than would normally be expected given the natural conditions but does have the potential to be improved. Another key factor influencing fish diversity is connectivity to downstream waterways. Two of the four sites at which no fish were caught discharge into the HCC reticulated stormwater network. Three other unsurveyed drains within the Structure Plan area also discharge into the reticulated stormwater network and could be expected to have low or no fish populations. The other two sites at which no fish were caught are on the eastern branch of the Mangaonua Stream tributary which includes a pipe on a steep gradient to convey water to the bottom of the Mangaonua Stream tributary gully. It is unlikely that fish could traverse this pipe to populate the drain network in this area Black Mudfish Mudfish usually occupy streams that dry out during summer (Hicks & Barrier 1996), prefer emergent vegetation over streams and wetlands (Ling 2001), and benefit from the exclusion of eels and other species (Hicks & Barrier 1996, McDonald 2007). Research also suggests that regular clearing of drains degrades habitat and eventually leads to elimination of mudfish (Ling 2001). On this basis, populations of mudfish could be expected to be low in waterways within the Ruakura Structure Plan area. However, Boffa Miskell s experience has been that regularly excavated Waikato drains with little emergent vegetation do support populations of black mudfish ranging from juveniles to adults. On the basis of the fish survey, Freshwater Fish Database records and our experience, we expect the Structure Plan area drains that are hydrologically connected to a downstream catchment will support a moderate to large population of black mudfish. The presence of adult eels may limit mudfish populations in smaller waterways. 21

26 The waterways of the Structure Plan area cover almost 21km (excluding pipes and minor dish channels), of which most are hydrologically connected to a downstream catchment. We recommend assessing the size of the mudfish populations within the Structure Plan area to determine the potential significance of the waterways as habitats of indigenous fauna. Plate 7: Adult black mudfish at Percival Road drain. 8.0 Avifauna & Bats The Ornithological Society records 25 native and 16 introduced species of birds that occur in and around Hamilton as shown in Table 9. Most species occupy open habitats and pasture, with few forest species present. There is also a large proportion of water birds and waders (including some threatened species) associated with the Waikato River and remnant wetlands. Morepork and occasional kereru are associated with the Hamilton gully systems (Clarkson & McQueen, 2004). No avifauna surveys have been recorded at Ruakura. Based on our observations, it is likely that the area is dominated by introduced and common native species that can occupy open farmland. The Structure Plan area is largely unsuitable for native forest birds due to the lack of native vegetation and bush areas. Table 9: Native and introduced bird species recorded in Hamilton (Source: Cornes & Thomson 2011) Latin name Common name Threat Status (Miskelly et al., 2008) Acridotheres tristis Mynah Introduced and Naturalised Anas gracilis Grey teal Not Threatened Anas platyrhynchos Mallard Introduced and Naturalised Anas rhynchotis NZ shoveller Not Threatened Anas superciliosa Grey duck Threatened: Nationally Critical Anser anser Domestic geese Introduced and Naturalised Anthornis melanura Bellbird Not Threatened Ardea novaehollandiae White faced heron Not Threatened 22