REPORT

Waikato River Water Take and Discharge Proposal - Board of Inquiry River Ecology Assessment

Prepared for Watercare Services Limited Prepared by Tonkin & Taylor Ltd Date December 2020 Job Number 1014753.100

Tonkin & Taylor Ltd December 2020 Waikato River Water Take and Discharge Proposal - Board of Inquiry - River Ecology Assessment Job No: 1014753.100 Watercare Services Limited Document Control

Title: Waikato River Water Take and Discharge Proposal - Board of Inquiry Date Version Description Prepared by: Reviewed Authorised by: by: 11/12/2020 1.0 Final Liza Kabrle Dean Miller Peter Roan

Distribution: Watercare Services Limited 1 electronic copy Tonkin & Taylor Ltd (FILE) 1 electronic copy Table of contents

1 Introduction 1 2 Project background 4 2.1 Description of the consent application 4 2.2 Proposed abstraction rate and intake design 5 2.3 Indicative construction methodology 6 3 Waikato Regional Plan 8 3.1 Planning limitations 8 3.2 Information requirements 8 3.3 Waikato Regional Plan Change 1 (Healthy Rivers) 9 3.4 National Policy Statement – Freshwater Management 9 4 Assessment methodology 11 4.1 Step one: Assigning ecological value 11 4.2 Step two: Assess magnitude of effect 11 4.3 Step three: Assessment of the level of effects 12 4.4 Assigning an RMA interpretation to level of effect 12 5 Ecology of the Waikato River 13 5.1 Waikato River water quality 13 5.1.1 WRC water quality records 13 5.1.2 Watercare Waikato River water quality records 14 5.2 River freshwater biota 15 5.2.1 Macroinvertebrates 15 5.2.2 Fisheries 16 5.3 Riparian and wetland values 19 6 Existing intake structure 21 6.1 Existing intake design 21 6.2 Intake impingement and entrainment records 21 6.3 Impingement and entrainment monitoring results 22 7 Existing WTP discharges 25 7.1 Quantity of the existing WTP discharges 25 7.2 Quality of the existing WTP discharges 26 7.2.1 Dimensions of the mixing zone 28 8 Assessment of ecological effects 30 8.1 Assigning ecological value 30 8.2 Construction effects 31 8.2.1 Effects on river water quality 31 8.2.2 Effects on the river bed 32 8.2.3 Effects on river freshwater biota 32 8.3 Operational effects 33 8.3.1 Effects on river temperature and dissolved oxygen due to reduced flow in the Waikato River 33 8.3.2 Effects on river water quality through routine cleaning of the screens 38 8.3.3 Effect of the WTP discharge on water quality and the ecology of the lower Waikato River 39 8.3.4 Effects on river freshwater biota through the abstraction of water and operation of the intake screens 44 8.4 Summary of effects 49

Tonkin & Taylor Ltd Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd 9 Reference list 54 10 Applicability 57 Appendix A : Waikato River Take - Wetland Classification for Waikato Intake Structure (Beca, 2020) Appendix B : EcIA Guidelines Tables Appendix C : Waikato Raw Water - Watercare 2016 – 2020 Appendix D : Effect of the proposed discharge on Waikato River FAC concentrations at Q5 low flow (185.9 m3/s) Appendix E : Bench testing of free available chlorine (Source: Watercare 2017)

Tonkin & Taylor Ltd Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Executive summary

Introduction Watercare Services Limited (Watercare) is seeking consent through the Board of Inquiry process to abstract a further 150,000 m3/day net from the Waikato River, year round, as well as consents for the construction and operation of a new water intake and the discharge of process water and off- spec water. This report provides an assessment of the river ecological effects prepared to inform the application to be considered by the Board of Inquiry. This report provides an assessment of the ecological values of the lower Waikato River, downstream of the Waikato Intake. An assessment is made of the effects associated with the construction and operation of the intake structure, the proposed water take and any associated changes in water levels and flow and proposed Water Treatment Plant discharges on these values. Specifically, the report: · Describes freshwater values within the lower Waikato River based on a desktop review and monitoring information from the existing Waikato Water Treatment plant. · Provides an assessment of effects on ecological values in general accordance with Ecological Institute of New Zealand (EIANZ) guidelines. · Describes measures to avoid, remedy, mitigate the potential adverse effects, where necessary. Freshwater values The Waikato River provides for a diverse range of native fish species, as well as a pathway for various species to migrate upstream and downstream to complete their lifecycles. Of the nineteen native fish species recorded in the lower Waikato River, two are considered to be ‘Threatened’ and eight are considered to be ‘At risk’ (Dunn et al., 2018). However, when assigning an overall ecological value to the lower Waikato River, a number of other factors have also been taken into consideration. For example: · Macroinvertebrate communities recorded at WRC sites closest to the intake do not appear to contain taxa that are particularly sensitive to changes in water quality or habitat disturbance; · Riparian vegetation is largely dominated by exotic species including willows and alder; and · Water quality is noted as “Unsatisfactory” for some key parameters such as total phosphorus and turbidity. When taking all these factors into consideration, for the purpose of this assessment we have considered the lower Waikato River as being of High ecological value. However, the Nationally and Regionally significant wetlands approximately 13 km downstream have specifically been given an ecological value of Very High. Freshwater effects The potential effects on freshwater values can be broken down into short term effects associated with the construction and long term effects relating to the operation of the intake and operational discharges. Potential effects related to the construction phase include effects on river water quality, the river bed and river freshwater biota associated with the piling activities and construction of a coffer dam. For the operational phase this effects assessment focuses on potential effects on water quality and river biota as a result of changes to water levels and flow due to the abstraction, changes to water quality associated with operational discharges into the Waikato River and the potential effects associated with the intake structure and screens on river biota.

Tonkin & Taylor Ltd Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Potential effects during the construction period have been minimised as far as practicable by minimising the footprint of temporary and permanent structures on the river bed, disposing any spoil from the pilling away from the river, ensuring water contaminated with cement is not discharged directly into the river and having appropriate emergency spill kits are held on site. Potential for longer term effects on native fish will be minimised or mitigated through locating the screens in fast flowing water away from the bank but not in the centre of the river, installing screens with a 1.5 mm slot widths on the wedge wire screen and “approach” velocities of less than 0.15 metres per second. To maximise the protection it is also proposed that water velocities parallel with the screen (i.e. the sweep velocity) would be at least twice the approach velocity. Water quality effects due to discharges will be managed by including limits for key contaminants in the consent, de-chlorination is proposed where necessary and high dosage glycerine removed from site rather than discharging into the river. Conclusion Overall, the level of effects on river ecological values associated with the construction and operation of the Waikato Intake structure, abstraction of the water from the Waikato River and operational discharges will be between Low and Very Low. Therefore, the proposal’s overall level of effect on river ecological values is Low. There can be a high level of confidence in our predictions of effects due to the existing monitoring that has occurred for a similar intake structure and WTP discharge regime operating immediately adjacent to the location proposed under this application. Given the proposed works and design, and overall effect on ecological values as determined through this assessment, no further mitigation measures beyond those identified in this report, and included as part of the proposal, are considered to be required.

Tonkin & Taylor Ltd Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd 1 Introduction

Watercare Services Limited (Watercare) is a lifeline utility providing water and wastewater services to a population of 1.7 million people in Auckland. Its services are vital for life, keep people safe and help communities to flourish. More specifically, Watercare is the council-controlled organisation of Auckland Council responsible for municipal water supply within Auckland, and the provider of bulk water supply services to Pokeno and Tuakau in the Waikato District1. Watercare supplies approximately 440,000 cubic metres of water per day (m3/day) on average across the year, derived from a range of sources and treated to the Ministry of Health Drinking Water Standards for New Zealand 2005 (revised 2018). Watercare’s three main water supply sources are:2 · Water storage lakes in the Hūnua and Waitākere ranges; · A groundwater aquifer in Onehunga; and · The Waikato River. The exact proportion supplied from each source varies daily, depending on a range of factors including the levels in the storage lakes, forecast rainfall, treatment plant capacity, and maintenance requirements. In December 2013, Watercare applied to the Waikato Regional Council (“WRC”) for resource consents to authorise abstracting an additional 200,000 m3/day (net) of water from the Waikato River, a new water intake structure and discharges from a new water treatment plant. Since that time, Watercare’s water take application (and the associated applications) have been on hold while the WRC processes and determines other applications to take water from the Waikato River Catchment that were lodged before Watercare’s application. During the period from late 2019 through to mid-2020, the Auckland region experienced one of the most extreme drought events in modern times with rainfall for the period between January and May 2020 being approximately 30 % of what would normally be expected for that period. At Watercare’s recommendation, in May 2020 Auckland Council imposed water use restrictions in Auckland for the first time since the early 1990s. Watercare also took additional steps to improve security of supply during the drought by exercising emergency powers under section 330 of the Resource Management Act 1991 (RMA),3 and by re-establishing supply from previously decommissioned sources.4 While the above steps have been taken to ensure Auckland’s short-term water supply requirements are met, the focus has now turned to the future. Watercare focus remains planning for water demand over the long term by securing sustainably sourced water to achieve: · Certainty of supply in up to a 1:100-year drought with 15 % residual dam storage; and · Certainty of supply to meet the peak demand. On 30 June 2020, after considering advice provided by the Environmental Protection Authority, the Minister for Environment issued a direction under section 142(2) of the RMA to call in Watercare’s 2013 application and refer the matter to a Board of Inquiry to determine the application. The Minister’s direction recognised Watercare’s application as a proposal of national significance.

1 Under a bulk supply agreement with Waikato District. 2 Watercare also operates individual water supplies from various sources including groundwater and surface water for several other communities such as Muriwai, Algies Bay, Snells Beach, Bombay, Waiuku, Warkworth, Helensville and Wellsford. 3 Reduced environmental flows from the Waitakere, Wairoa and Cosseys Storage Lakes, and a short term take from the Waikato River. 4 Groundwater bores at Pukekohe and the Hays Creek Storage Lake in Papakura.

Tonkin & Taylor Ltd 1 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Given the passage of time since the 2013 application was lodged, Watercare has updated the application to address a range of matters including updates to population and demand assessments, changes to the policy framework within which the application is to be considered, consultation that has taken place, reassessment of potential water supply sources and intake options, and updated assessments of environmental effects including the effect that granting Watercare’s application would have on the allocation available to other users. The updated application will be heard by the Board of Inquiry. The most significant revision to the 2013 application, resulting directly from Watercare’s ongoing engagement with Waikato-Tainui is a reduction in the volume of the proposed water take from 200,000 m3/day (net) to 150,000 m3/day (net). This reduction reflects Waikato-Tainui’s special relationship with the Waikato River as outlined in the Waikato-Tainui Raupatu Claims (Waikato River) Settlement Act 2010. It recognises Waikato-Tainui’s relationship with the Waikato River and its respect for the River lies at the heart of Waikato-Tainui’s spiritual and physical wellbeing, tribal identity and culture. Watercare currently holds three resource consents authorising the abstraction of water from the Waikato River adjacent to the Waikato Water Treatment Plant (Waikato WTP) near Tuakau as follows: a Resource consent 960089.01.04 authorising a net take rate of up to 150,000 m3/day at any time of the year; b Resource consent 141825.01.01 (referred to as the “Seasonal Water Take” consent) authorising a net take rate of up to: - 100,000 m3/day during the period 1 May to 30 September (inclusive); and - 100,000 m3/day during the period 1 October to 30 April (inclusive) when the seven-day rolling average flow of the Waikato River at Rangiriri exceeds 330.03 m3/second. c Resource consent 142090.01.01 (referred to as the “Hamilton City Council Water Allocation” consent), authorising a net take rate of up to 25,000 m3/day (or such lesser volume as determined by Hamilton City Council as being available for any given day) during the period 1 October to 30 April (inclusive). This is a short-term consent that expires on 1 May 2023. In the event that the consent sought through the Board of Inquiry process is granted for the volume sought, Watercare proposes that its Seasonal Water Take consent and Hamilton City Council Water Allocation consent would be surrendered. Watercare’s combined take from the Waikato River under its existing resource consent 960089.01.04, and the new water take consent sought through the Board of Inquiry would therefore not exceed a year round net take volume of 300,000 m3/day. This report provides an assessment of the river ecological effects associated with the construction and operation of the intake structure, the discharge of process water and off-spec water and river ecological effects associated with any changes in water levels and flow associated with the water take. This report has been prepared to inform the application to be considered by the Board of Inquiry. The report is presented in the following sections: · Section 1: Introduction; · Section 2: Project background; · Section 3: Summary of the Waikato Regional Plan (WRP) key provisions relevant to assessment; · Section 4: A summary of the assessment methodology; · Section 5: Review of the existing ecology of the Waikato River; · Section 6: Relevant monitoring data for the existing intake structure;

Tonkin & Taylor Ltd 2 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd · Section 7: Relevant monitoring data for the existing WTP discharges; and · Section 8: An assessment of the river ecological effects of the proposal. This report should be read in conjunction with the Waikato Intake Hydrological Assessment (T+T, 2020a). This document has been prepared in accordance with Tonkin & Taylor Limited’s (T+T) proposal dated 23 October 2020.

Tonkin & Taylor Ltd 3 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd 2 Project background

2.1 Description of the consent application Watercare is seeking consent through the Board of Inquiry process to take a further 150,000 m3/day (net) from the Waikato River year round. As outlined in the introduction above, in the event this consent is granted by the Board of Inquiry for the quantity sought, Watercare’s combined take from the Waikato River under its existing resource consent 960089.01.04 and the new water take granted by the Board of Inquiry would not exceed a year round take limit of 300,000 m3/day (net). Watercare would surrender its Seasonal Take and HCC Take. This additional water would be treated at a new treatment plant on the same site as the existing Waikato WTP. Watercare is applying for consent for the activities described in Table 2-1.

Table 2-1: Watercare’s resource consent application seeks authorisation for the following activities

Consent Activity Type Water To take and use up to 150,000 m3/day (net) of water from the Waikato River at or about New Permit Zealand Transverse Mercator [2000] (“NZTM”) Map Reference 1776957E, 5872040N for municipal supply purposes. This is the same as Application #AUTH131259.01.01 as lodged with WRC in 2013 except that the take volume is reduced from 200,000 m3/day. Land Use To operate and maintain water intake and discharge structures and pipelines partly in and on Consent the bed of the Waikato River and, partly in or over the Waikato River at or about NZTM Map Reference 1776957E, 5872040N. This is the same as Application #AUTH131259.02.01 as lodged with WRC in 2013. Discharge To discharge: Permit a) up to 20,000 m3/day of process water arising from various water treatment operations into the Waikato River in the vicinity of the intake structure; b) Treated water that does not meet New Zealand Drinking Water Standards into the Waikato River in the vicinity of the intake structure; and c) Water, air, and river material from the backwashing of intake screens into the Waikato River; all at a rate of up to 3.2 m3/second at or about NZTM Map Reference 1776957E, 5872040N. This is the same as Applications #AUTH131259.03.01, AUTH131259.04.01 and AUTH131259.05.01 as lodged with WRC in 2013 except that the three applications are combined into one consent, as has been done with the existing Waikato WTP discharge consent and the discharge volume has been reduced from 30,000 m3/day to 20,000 m3/day. Land Use To undertake activities in, on, under, or over the bed of the Waikato River for the purposes of Consent enabling the construction of water intake and discharge structures and pipelines, including erecting intake structures and pipelines, erecting, using and removing a coffer dam structure and temporary access platform and all associated disturbance of the bed of the Waikato River, all located at or about NZTM Map Reference 1776957E, 5872040N. This is the same as Application #AUTH131259.06.01 as lodged with WRC in 2013, although the potential river bed disturbance area will be less than that originally envisaged due to a smaller area to be retained by the proposed coffer dam. Water To dam, divert and take water associated with the construction of a coffer dam around the Permit construction area for the intake and discharge structures and pipelines and associated dewatering activities within the coffer dam area for the purposes of enabling the construction

Tonkin & Taylor Ltd 4 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Consent Activity Type of a new intake and discharge structures and pipelines at or about NZTM Map Reference 1776957E, 5872040N. This is the same as Application #AUTH131259.07.01 as lodged with WRC in 2013, although the extent of the area enclosed by the coffer dam will be less than that originally envisaged. Discharge To discharge water into the Waikato River from dewatering the work area behind a coffer Permit dam installed for the purposes of enabling the construction of an intake and discharge structures and pipelines adjacent to the existing Watercare intake, at or about NZTM Map Reference 1776957E, 5872040N. This is the same as Application #AUTH131259.09.01 as lodged with WRC in 2013, although the extent of the area enclosed by the coffer dam will be less than that originally envisaged.

2.2 Proposed abstraction rate and intake design Watercare proposes to increase the take from the Waikato River through the development of a new intake structure and a new WTP, referred to as the “Waikato A WTP”, located at the existing site. A summary of the existing abstraction, proposed new abstraction and combined abstraction is provided in Table 2-2.

Table 2-2: Existing maximum abstraction, new abstraction and combined abstraction rates used as part of this assessment

Activity Presently authorised abstractions Proposed new abstractions Takes 150,000 m3/day (net) from the river year round 2.45 Incremental: 3.20 m3/s* 150,000 m3/day m3/s* 250,000 m3/day (net) when river flow is equal to (net) from the river or greater than: year round · median flow at Rangiriri (330.03 m3/s) from 1 October to 30 April (inclusive); and 5.23 Combined: 3 3 3 · 90% of q5 at Rangiriri (163.53 m /s) for ten m /s* 300,000 m /day 5.65 consecutive days from 1 May to 30 September (net) from the river m3/s* (inclusive) year round To be surrendered following granting of this consent application.

3 25,000 m /day (net) transferred allocation from 2.45 Hamilton City Council m3/s* To be surrendered following granting of this consent application. Discharges 20,000 m3/day 2.45 Incremental: 2.45 (process m3/s 20,000 m3/day m3/s discharges only) Combined: 4.90 3 40,000 m3/day m /s *Maximum instantaneous rate of abstraction The Waikato A WTP and all land-based infrastructure (e.g. pipes and pump stations) do not form part of the proposal that is before the Board of Inquiry. However, a high level concept design for the

Tonkin & Taylor Ltd 5 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Waikato A WTP is set out in the Waikato A WTP Concept Report. The proposed location of the additional intake structures has been confirmed, following an options assessment process, and will be adjacent to the existing intake structures. The proposed additional intake structures will be largely the same as the existing intake structures, subject only to a decision being made (post consenting) as to whether a brushed system or sparging (as occurs now) is used for clearing the intake screens. The following assumptions have been made as part of our assessment of ecological effects: · Discharges from the new WTP will typically be of the same quality as current discharges (or better) as the treatment process will be the same as in the existing WTP, although the rate for process discharges will increase; and · The intake structure and screens will be designed to the same specifications as the current intake with regards to screen slot size, and approach and sweep velocities. For the purpose of this assessment we have considered the following design options: - wedge wire screens with an air sparging screen cleaning system (as per the existing intake); and - wedge wire screens with a mechanical brush cleaning system. · The assessments presented in this report have primarily used the existing 150,000 m3/day (net) take as the baseline with respect to river flow condition and for considering the effects of the proposed additional take. However, as can be noted from Table 2-2, it is proposed that the new additional take will be drawn from the river at a cumulative instantaneous rate only slightly greater than that authorised under existing consents, albeit year round rather than dependent on season or whether the River is above median flow. Thus, the cumulative effects reported below are similar to those for already consented activities with reference to the instantaneous rate.

2.3 Indicative construction methodology The high-level construction methodology for the proposed intake described below is as set out in the Waikato River Take – Waikato Intake Feasibility Report (GHD, 2020) based on using trenchless methods for constructing the tunnel between the raw water pump station and the intake. Depending on the final alignment and detailed geotechnical investigations, the trenchless methodology could utilise a tunnel boring machine (TBM), drill & blast or a road header. Note that the existing tunnel was constructed using a drill & blast method. The envisaged methodology is summarised as follows: · Construct a temporary access track and platform. These temporary works are envisaged to be on temporary steel piles driven into the riverbank and bed; · Install a piled cofferdam and pump out the cofferdam. These temporary works would be large enough to allow the TBM to be removed after drilling from the pump station site towards the river. If a TBM is not used, a cofferdam would still be required to provide a dry exit point for the tunnelling works; · Excavate the tunnelling launch pit in the same location as the pump station wet well; · Complete the tunnel and raw water pipeline installation and dispose of waste material to approved landfill or as fill on site; · Complete a trenchless conduit for airburst or control cable duct, depending on the screen cleaning option installed. Alternatively, these services could be installed in common tunnel that also houses the raw water pipeline; · Drive support piles for the intake manifold and intake pipe supports; · Construct the intake support structure on the piles;

Tonkin & Taylor Ltd 6 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd · Fabricate the intake manifold and pipework and install on the support structure, up to the cofferdam, by submerging the intake assembly (including screens); · Flood the cofferdam, remove the piles, and connect the submerged inlet pipework to the supply pipeline underwater using divers; · Extend and install the off-spec pipeline; · Remove the temporary access track and platform; and · Reinstate the riverbank.

Tonkin & Taylor Ltd 7 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd 3 Waikato Regional Plan

This section presents a summary of Waikato Regional Plan (WRP) planning limitations, information requirements and assessment criteria relevant to this ecology assessment. Further information in relation to planning requirements including the National Policy Statement for Freshwater Management 2020 is set out in the AEE.

3.1 Planning limitations The WRP contains policies and methods to manage the natural and physical resources of the Waikato region. The Waikato River at the water intake site is subject to a number of planning controls to ensure that adverse effects on the environment are appropriately managed. The Waikato River at the intake location is shown on the WRP Water Management Class Map R12 as having the following Water Management Classes: · Surface Water Class; · Both Trout Fisheries and Trout Spawning Habitat Water Class and Indigenous Fisheries and Fish Habitat Water Class (although Chapter 3.2 Policy 7 exempts the main stem of the Waikato River from matters relating to trout spawning habitat); and · Contact Recreation Water Class In addition, the river margins are a High Risk Erosion Area in terms of Chapter 5 of the WRP (land and soil). Suspended solids standards relevant to the application are as follows (3.2.4.6): a The activity or discharge shall not increase the concentration of suspended solids in the receiving water by more than 10 percent; and either b The suspended solids concentration of the discharge shall not exceed 100 grams per cubic metre; or c The activity or discharge shall not result in any of the following receiving water standards being breached: - i) in Indigenous Fisheries and Fish Habitat Class waters – 80 grams per cubic metre suspended solids concentration; - ii) in Significant Trout Fisheries and Trout Habitat Class waters – 25 grams per cubic metre suspended solids concentration; and - iii) in Contact Recreation Class waters – black disc horizontal visibility greater than 1.6 metres. Key intake velocity and screen size requirements are as follows (3.2.4.2): · Water intake structures to be screened with a mesh aperture size not exceeding 3 mm in diameter at locations less than 100 m above mean sea level (which is applicable for the proposed intake); and · Maximum intake velocity [approach] shall not exceed 0.3 m/s.

3.2 Information requirements Chapter 8 of the WRP sets out the information that is required to be submitted with a resource consent application. Each of the Chapters of the WRP sets out the objectives, policies, rules and assessment criteria (policies) and standards against which an application is to be assessed. A summary of the criteria and standards that are relevant to this ecological assessment are as follows:

Tonkin & Taylor Ltd 8 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd · Minimise fish entrapment and entrainment at water intake structures; · Minimise adverse effects on fish spawning patterns; · Minimise structural and temperature barriers and changes in flow regimes that would otherwise prevent fish from completing their life cycle and/or maintaining self-sustaining populations, including migration and spawning; · Minimise physical disturbance to aquatic habitat; · Minimise increases in undesirable aquatic growths; · Maintain sufficient flow and/ or water depth to allow for the unimpeded passage of fish and the maintenance of fish habitat and spawning; · Minimise effects on ecological values and biodiversity and the benefits of the natural flow regime variability, including sediment transport and natural flushing and flood flows; · Minimise effects on wetlands, areas of significant indigenous vegetation, or significant habitats for indigenous fauna; · Whether appropriate mitigation measures are implemented, including: environmental flows, the location of the abstraction, maintenance of upstream and downstream fish passage, riparian planting, etc; · Ensure discharges do not result in significant effects on the Coastal Marine Area, significant wetlands, cave ecosystems or lakes; · Minimise damage to riparian vegetation and soil, and effects on riverbed and bank stability; · Minimise effect of instream structures on water quality, flow regimes, aquatic ecosystems, fish passage for trout and indigenous fish; · Minimise effect of bed and bank disturbance on natural flow characteristics and hydraulic processes (such as sediment transport) of rivers or the pattern and range of natural water level fluctuations; and · Minimise effect of bed and bank disturbance on diversity and composition of aquatic and riparian habitat.

3.3 Waikato Regional Plan Change 1 (Healthy Rivers) It is noted that WRC has notified a plan change to the WRP with a focus on the Waikato River and its catchment (Healthy Rivers - Plan Change 1). The WRC made its decision on Plan Change 1 on 18 March 2020. At the time of this assessment the decision is still subject to an appeals process, and may therefore still be subject to change through that process. However, the abstraction and discharge activities proposed are unlikely to effect the key attributes/targets included in Plan Change 1 which focus on nitrogen, phosphorus, sediment (clarity and chlorophyll a) and microbial pathogens (using E. coli. as a proxy).

3.4 National Policy Statement – Freshwater Management The National Policy Statement for Freshwater Management 2020 (NPS FM) has to be given effect to in Regional Plans. The NPS FM introduces several new ‘attributes’ and ‘bottom lines’ for water quality and ecological health in streams as well as new policies around the avoidance of loss of streams and natural wetlands. The NPS FM requires that the management of water gives effect to Te Mana o Te Wai with the aim to improve degraded water bodies, and maintain or improve all others using the bottom lines defined in the Freshwater NPS. The proposed abstraction and discharges are unlikely to effect the key attributes included in the National Objectives Framework (NOF) of NPS FM. Effects on dissolved oxygen (DO, discussed in section 8.3.1) and suspended sediment (discussed in section 8.3.3.5) have been addressed in this

Tonkin & Taylor Ltd 9 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd report. NOF attributes for fish, macroinvertebrates and deposited fine sediments are relevant to wadable rivers of which the Waikato River is not. However, an assessment of effects on river biota is provided in sections 8.2.3 and 8.3.4 of this report. A classification assessment has been undertaken of wetlands within 100 m of the intake, pipework and discharge point (Beca, 2020, see Appendix A). This assessment concluded no natural wetlands as defined under the NPS FM are present within 100 m of the intake, pipework and discharge point. As are result wetlands within 100 m of the intake have not been discussed further.

Tonkin & Taylor Ltd 10 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd 4 Assessment methodology

The assessment of ecological effects broadly follows the Ecological Impact Assessment Guidelines (EcIAG) (Roper-Lindsay et al, 2018), with some adaptation for different fauna and ecosystem types. Using a standard framework and matrix approach such as this provides a consistent and transparent assessment of ecological effects and is considered to be best industry practice. The EcIAG framework provides structure but needs to incorporate sound ecological judgement to be meaningful. The guidelines include a three-step process for making an ecological impact assessment: 1 Assign an ecological value to the existing environment; 2 Assess the magnitude of ecological effects from the proposed activity on the environment; and 3 Assess the overall level of effect to determine if effects management is required. The three steps are described in more detail below.

4.1 Step one: Assigning ecological value Ecological values are assigned on a scale of ‘Negligible’ to ‘Very High’ based on species, communities, and habitats, using EcIAG criteria. Matters that may be considered when assigning ecological value to freshwater systems include representativeness, rarity/distinctiveness, diversity and ecological context. The relative importance of these matters is often driven by availability of empirical information (measured attributes such as Macroinvertebrate community index (MCI) or water quality data). For individual plant and animal species, the national threat status was also used to determine potential ecological values of the site. Aquatic ecological values have been assigned using ecological characteristics described in Appendix B Table B.1.

4.2 Step two: Assess magnitude of effect Magnitude of effect is a measure of the extent or scale of the effect of an activity and the degree of change that it will cause. The magnitude of an effect is scored on a scale of ‘Negligible’ to ‘Very High’ (Appendix B Table B.2) and is assessed in terms of: · Level of confidence in understanding the expected effect; · Spatial scale of the effect; · Duration and timescale of the effect (Appendix B Table B.3); · The permanence of the effect; and · Timing of the effect in respect of key ecological factors. The spatial scale for effects is considered in the context of the local and landscape scale as appropriate. In the case of this application we have considered the reach of the Waikato River downstream of the intake to the river month. We have called this the “Lower Waikato”. We have also assessed the magnitude of effect on the wetlands in the lower river specifically referred to as “lower wetlands”. Nationally significant wetlands are located in the islands and river margins that make up the Waikato River delta. These wetlands are located approximately 13 km downstream of the intake and extend downstream to river mouth (approximately 36 km downstream of the intake).

Tonkin & Taylor Ltd 11 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd 4.3 Step three: Assessment of the level of effects An overall level of effects is identified for each activity or habitat/fauna type affected by the application using a matrix approach (Appendix B: Table B.4) that combines the ecological values with the magnitude of effects resulting from the activity. The matrix describes an overall level of effect on a scale of ‘Very Low’ to ‘Very High’. Positive effects are also accounted for within the matrix to capture any positive effects on ecological values proposed as part of a project. The level of effect is then used to guide the extent and nature of the ecological management response required, which may include avoidance, remediation, mitigation, offsetting or compensation. The overall level of effects on each value (habitat or species) is assessed before and after recommendations to avoid, remedy or mitigate effects. Therefore, the need for and extent to which recommendations can reduce effects, if implemented, are clearly understood.

4.4 Assigning an RMA interpretation to level of effect The EcIAG process provides for the overall level of ecological effects to be translated to an ‘RMA effect’. The level of ‘RMA effect’ is determined by planners in consultation with ecologists and set out in the AEE report, rather than in an ecology report. This approach provides for consistency between the descriptions of ecological effects and other types of effects that may arise from a proposed activity, which may be considered elsewhere in the application documents.

Tonkin & Taylor Ltd 12 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd 5 Ecology of the Waikato River

This section provides a review of the water quality and river freshwater ecology of the Waikato River receiving environment.

5.1 Waikato River water quality

5.1.1 WRC water quality records WRC has been monitoring the water quality of the Waikato River and catchment since 1983. Samples are collected from 10 sites along the Waikato River between Taupo and the mouth on a monthly basis. At the confluence of the Waikato River and the Waipa River, a major tributary joining at Ngāruawāhia, turbidity concentrations increase as a result of turbid water from the Waipa catchment. On occasion, Waipa River turbidity can inhibit the upstream migration of some native galaxiid fish species (WRC, 2008). This turbid water is largely due to land use activities and areas of instability in the upper Waipa catchment (WRC, 2008). Overall, water quality in the Waikato River decreases with distance downstream. Turbidity levels increase with distance downstream largely due to the increased sediment load of the Waipa River. Nutrient levels also increase with distance downstream due to a range of diffuse and point discharge sources. Temperature does show an increase between the cooler waters discharged from and downstream of Lake Taupō compared to the Lower Waikato River. Dissolved oxygen (DO), pH and ammonia levels are usually at Satisfactory levels. WRC monitoring sites most relevant to the Watercare intake are the site at Mercer Bridge six kilometres upstream, and at Tuakau Bridge approximately 5 km downstream. Subsets of results for the Mercer Bridge and Tuakau Bridge monthly monitoring between January 2012 and November 2020 are presented in Table 5-1 and in Table 5-2 respectively (WRC, 2020a).

Table 5-1: Monthly water quality at Mercer Bridge between January 2012 and November 2020

Parameter Mercer Bridge Range Average Median Average Ecological Health (WRC, 2020a) DO (% saturation) 74.4 to 115.6 95.5 95.5 Excellent Conductivity (mS/m at 25 12.8 to 17.5 15.4 15.4 Not applicable °C) Nitrate/Nitrite Nitrogen 0.034 to 1.59 0.47 0.43 Not applicable (g/m3) Total Phosphorus (g/m3) 0.026 to 0.05 0.05 Unsatisfactory 0.186 pH 6.7 to 8.1 7.5 7.5 Excellent Temperature (°C) 9.7 to 25.6 16.8 16.6 Not applicable Turbidity (NTU) 2.4 to 74 11.1 8.15 Unsatisfactory

Tonkin & Taylor Ltd 13 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Table 5-2: Monthly water quality at Tuakau between January 2012 and November 2020

Parameter Mercer Bridge Range Average Median Average Ecological Health (WRC, 2020a) DO (% saturation) 67.6 to 124.9 97.1 97 Excellent Conductivity (mS/m at 25 12.3 to 18.6 15.5 15.5 Not applicable °C) Nitrate/Nitrite Nitrogen 0.01 to 1.39 0.46 0.42 Not applicable (g/m3) Total Phosphorus (g/m3) 0.026 to 0.058 0.047 Unsatisfactory 0.480 pH 6.8 to 8.2 7.5 7.5 Excellent Temperature (°C) 10.3 to 25.7 17.2 17.0 Not applicable Turbidity (NTU) 2.2 – 84 11.3 8.85 Unsatisfactory

Water quality conditions at Mercer and Tuakau are generally similar although Tuakau does have a greater tidal influence than upstream at Mercer that affects water levels. DO and pH levels were generally classified as Excellent with regards to average ecological health (WRC, 2020a), whereas total phosphorus and turbidity were classified as Unsatisfactory.

5.1.2 Watercare Waikato River water quality records Watercare collects water quality data for the raw water abstracted from the Waikato River at the existing intake. Raw river water samples are analysed for a range of parameters with a subset of those presented in Table 5-3 below.

Table 5-3: Quality of the raw water abstracted from the Waikato River at the existing water intake.

Parameter Number of Range Average Median tests pH 275 6.6 – 8.2* 7.5 7.5 Aluminium Total (mg/L) 283 0.005 – 3.400 0.688 0.550 Fluoride (mg/L) 56 0.09 – 0.20 0.14 0.13 Total suspended solids (mg/L) 76 5 - 100 23 18.5 *Outlier of pH 10.5 removed (24/01/2018) During the construction phase associated with this application one of the key water quality considerations is total suspended solids due to the potential for sediment release during piling activities. Figure 5-1 shows graphically the variability of total suspended solids within the raw water abstracted at the existing Waikato intake. Total suspended solids in the raw water at the Waikato Intake tend to vary between 5 mg/L and 30 mg/L with one off events where levels reach up to 100 mg/L. Details around discharge water quality can be found in Section 7 of this assessment.

Tonkin & Taylor Ltd 14 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Figure 5-1: Raw Waikato River water total suspended solids between 29/01/2015 and 18/3/2020 (collected by Watercare).

5.2 River freshwater biota

5.2.1 Macroinvertebrates Data from key studies of macroinvertebrates communities in the Lower Waikato River have been summarised in Table 5-4. Aquatic macroinvertebrate communities in the lower Waikato River are characterised by species that prefer soft bottomed, macrophyte dominated habitats. Littoral macroinvertebrate communities downstream of Karapiro Dam become increasingly dominated with distance by crustacea, including the freshwater shrimp Paratya curvirostris and the amphipod Paracalliope fluviatilis (Collier & Lill, 2008; Collier & Hogg, 2010). The dominance of crustacea has been linked to the food sources associated with phytoplankton and fine particulate organic matter (Collier et al, 2011). Benthic macroinvertebrate communities have been found to be less dominated by crustacea and more dominated by taxa tolerant of fine sediment such as oligochaete worms (Collier & Hamer, 2014).

Table 5-4: Lower Waikato River macroinvertebrate data

Study WRC, 2001a WRC, 2011 Collier, K. C. WRC, 2014 WRC, 2014 and Lill, A. (2008) Site Tuakau Bridge Rangiriri Bridge Tuakau (Site 41) Mercer (T22) Mercer (T22) Sampling Littoral Artificial Littoral D Net, Littoral D Net, Air lift, method macrophyte substrates sweep of sweep of benthic samples (Egeria, (perspex and vegetation, vegetation, Elodea) wood) wood, benthic wood, submerged roots Timing Mid-summer Sept, Jan and February Autumn 2012 Autumn May (2 months) 2012

Tonkin & Taylor Ltd 15 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Study WRC, 2001a WRC, 2011 Collier, K. C. WRC, 2014 WRC, 2014 and Lill, A. (2008) Number of taxa 18 8.9 and 10.8 13 18 1 MCI 67.5 - - - - Dominant Platyhelminthes, Crustacea, Mollusca, Crustacea Oligochaeta groups Mollusca Trichoptera, Crustacea Oligochaeta Dominant taxa Cura (flatworm), - Paracalliope Naididae Ferrissia (limpet)

Standard macroinvertebrate community metrics (e.g. Macroinvertebrate Community Index or MCI) used to assess water and habitat quality cannot be meaningfully applied to large river systems like the lower Waikato River. Indices specific to large rivers have also not yet been developed. However, the communities recorded in the lower river (below the hydro dams) do not appear to contain taxa that are particularly sensitive to changes in water quality or habitat availability. Macroinvertebrate communities within the littoral zone close to the shore will also be adaptive to large water level fluctuations as a result of both flow regulation due to the Waikato Hydro Scheme and tidal influences on water level.

5.2.2 Fisheries

5.2.2.1 Waikato River fish community The Waikato River is the longest river in New Zealand and is a significant migration pathway for many native fish species (WRC, 2001b). Nineteen native fish species have been identified in the river and its hydro lakes, along with ten exotic species (WRC, 2020b). Of these native fish species, two are considered to be ‘Threatened’, and seven are considered to be ‘At risk’ (Dunn et al, 2018). ‘Threatened’ species include lamprey (Geotria australis) and short-jawed kokopu (Galaxias postvectis). The ‘At risk’ species include: · īnanga (Galaxias maculatus); · longfin eel (Anguilla dieffenbachii); · torrent fish (Cheimarrichthys fosteri); · giant kokopu (Galaxias argenteus); · koaro (Galaxias brevipinnis); · black mudfish (Neochanna diversus); and · giant bully (Gobiomorphus gobiodes). Of the native species found in the river, three species tend to spend the majority of their life cycle in the marine environment (yellow-eyed mullet, grey mullet and flounder). The remaining species range between being catadromous (living in freshwater but migrating to spawn at sea), anadromous (spending the majority of their lives at sea then migrating upstream from the sea to spawn in freshwater), or amphidromous (spending part of their life at sea, but this marine stage is not directly related to spawning). Black mudfish and Cran’s bullies do not migrate as part of their lifecycle. Ten exotic fish species are present in the lower Waikato River. Koi carp dominates fish biomass, and its distribution extends up the Waipa River as far as Te Kuiti (WRC, 2008). Many of the exotic species can affect native fish communities through competition for space and food. Exotic species

Tonkin & Taylor Ltd 16 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd (particularly koi carp) can also modify habitats as a result of their own feeding behaviours, for example through uprooting aquatic plants and increasing water turbidity (WRC, 2008). Table 5-5 and Table 5-6 outline the native and exotic freshwater fish species found in the lower Waikato River respectively.

Table 5-5: Native freshwater fish and large crustaceans found in the lower Waikato River catchment

Common name Māori name Scientific name Risk classification* Migration classification** Yellow-eyed mullet Aua Aldrichetta forsteri NT marine species Shortfin eel Hao Anguilla australis NT catadromous Longfin eel Kuwharuwharu Anguilla AR-D catadromous dieffenbachii Australian longfin Anguilla reinhardtii C catadromous eel Lamprey Pirahau Geotria australis T-NV anadromous Torrentfish Papamoko Cheimarrichthys AR-D amphidromous fosteri Giant kokopu Kokopu Galaxias argenteus AR-D amphidromous Koaro Galaxias AR-D amphidromous brevipinnis Banded kokopu Para Galaxias fasciatus NT amphidromous Īnanga Galaxias maculatus AR-D amphidromous Short-jawed Galaxias postvectis T-NV amphidromous kokopu Black mudfish Neochanna AR-D non-diadromous diversus Giant bully Gobiomorphus AR-NU amphidromous gobiodes Common bully Pako Gobiomorphus NT amphidromous cotidianus Redfin bully Gobiomorphus NT amphidromous huttoni Cran’s bully Gobiomorphus NT non-diadromous basalis Grey mullet Mugil cephalus NT marine species Common smelt Ngaoire Retropinna NT anadromous Black flounder Patiki Rhombosolea NT marine species retiaria Freshwater Koura Paranephrops NT - crayfish planifrons Shrimp Kouraura Paratya curvirostris - - Source: New Zealand Freshwater Fish Database queried March 2020, WRC, 2008 * Dunn et al, 2018; Risk classification: NT =Non-threatened T-NV = Threated – National Vulnerable,

Tonkin & Taylor Ltd 17 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd AR-D = At risk – declining AR-NU = At risk- Naturally Uncommon C = Coloniser AR-R = At risk – relict. ** WRC, 2007; Definitions: Diadromous, general term meaning migrating at some stage of the lifecycle between freshwater and the sea Catadromous, living in freshwater but migrating to spawn at sea Anadromous, spend the majority of their lives at sea then migrate upstream from the sea to spawn in freshwater amphidromous, spend part of their lives at sea, but this marine stage is not directly related to spawning.

Table 5-6: Exotic (introduced) freshwater fish found in the lower Waikato River

Common name Scientific name Catfish Ameiurus nebulosus Goldfish Carassius auratus Grass carp Ctenopharyngodon idella Koi carp Cyprinus carpio Gambusia or mosquito fish Gambusia affinis Rainbow trout Oncorhynchus mykiss Perch Perca fluviatilis Brown trout Salmo trutta Rudd Scardinius erythropthalmus Tench Tinca Sources: WRC website and New Zealand Freshwater Fish Database March 2020

5.2.2.2 Spawning habitat Spawning habitat varies depending on fish species, with some species having more than one type of habitat. Freshwater eels spawn in the Pacific Ocean. Kokopu and koaro spawn along stream margins during freshes. Bullies lay their eggs on rocks, vegetation or other structures that are permanently inundated. During monitoring of the existing intake īnanga and smelt were identified as the species most likely to be affected by the intake. This is because the larvae of both species have been detected within the intake (penstock) and in the adjacent river channel. For this reason, the focus is on īnanga and smelt in the remainder of our assessment. Īnanga Īnanga (an ‘At Risk’ species) is the most important species of whitebait, as it makes up the majority of the yearly whitebait catch in most New Zealand rivers (Taylor, 2002). Īnanga are generally found in lowland and coastal rivers, lakes and wetlands. Unlike other galaxiid species, īnanga are poor climbers and therefore do not generally penetrate far inland. However, due to its low gradient, the lower Waikato River provides an uninterrupted migration pathway for īnanga upstream to the Karapiro Dam and over 200 km upstream in the Waipa River (New Zealand Freshwater Fish Database queried January 2020). Īnanga spawn in the freshwater intertidal zone during high spring tides. This spawning strategy requires that īnanga migrate downstream to appropriate spawning habitats. Not all īnanga migrate at the same time because spawning is spread out over several months, and some fish do not mature until their second or even third year (McDowall, 2000). Eggs are deposited amongst bankside vegetation so that they are immersed for prolonged periods of time. Īnanga show strong preferences

Tonkin & Taylor Ltd 18 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd for vegetation types that provide a cool, moist microclimate conducive to egg incubation (Hickford et al, 2010). It is known that īnanga egg fertilisation is possible in salinities up to 20 psu (Hicks et al, 2010). Although īnanga spawning has been recorded in all months other than August, peak spawning activity occurs from March to May (WRC, 2005; Hamer, 2007). Spawning sites have been known to move in response to changes in the range of tidal movement and disturbance of spawning sites (Mitchell, 1994; WRC, 2005). Eggs hatch on the following high spring tide and the larvae are washed out to sea where they grow into whitebait. Īnanga return to freshwater after spending about 21 to 23 weeks at sea (Meredith et al, 1989). Īnanga have been recorded rearing entirely in freshwater although it is much less common than the amphidromous life cycle. A range of sites on the lower Waikato River has been identified as known or possible īnanga spawning habitat. A number of spawning habitat surveys in lower Waikato River in the 1980s (Mitchell, 1990) and by NIWA in 2013 (Jones & Hamilton, 2014) detected īnanga spawning as far upstream as the Elbow Boat Ramp, which is approximately 10 km downstream of the existing intake. However, spawning sites are likely to extend much further upstream within the zone of tidal influence given that īnanga larvae have been detected in the river at the intake. Tidal influences on levels in the Waikato River extend as far as Rangiriri, however, saline intrusion is restricted to the lower reaches (approximately 10 km to 13 km upstream from the river mouth (Jones and Hamilton, 2014)). In the lower Waikato River, floodgates and the grazing of riverside margins have limited both the extent and quality of potential īnanga spawning habitat (WRC, 2008). Stopbanks close to the river margins may mean that īnanga habitat is more spatially constrained at high water levels than it is at low water levels (Jones and Hamilton, 2014). Smelt Smelt spawning is thought to occur on sand bars in the mid-channel and on sandy beaches in autumn (Mitchell, 1990). Fry then drift in the current towards the sea returning to the estuary between September and November. No specific smelt spawning areas have been identified in the Waikato River although smelt are known to be abundant there. Smelt are not threatened.

5.3 Riparian and wetland values Riparian vegetation along the lower Waikato River is largely dominated by willows (Salix sp.) and alder (Alnus glutnosa). However, there are still relatively extensive remnants of the original native vegetation, comprising Kahikatea (Dacrycarpus dacrydioides) forest, manuka (Leptospermum scoparium) and flax (Phormium tenax) (Clarkson et al., 2002). Riparian vegetation in the vicinity of the intake site is shown in Photograph 5.1, with willows dominating the left bank. The right bank is dominated by rock walls and limited riparian vegetation. The margins of the lower Waikato River include a number of Regionally, Nationally and Internationally significant wetlands (van der Zwan &Kessels, 2017). Nationally significant wetlands are located in the islands and river margins that make up the delta. The wetlands are noted as significant due to the likely presents of range of Threatened and At Risk birds and fish, the presence of breeding and foraging grounds for birds and potential īnanga spawning habitat (Envirostart Consulting Ltd, 2018; van der Zwan and Kessels, 2017). These wetlands are located approximately 13 km downstream of the intake. Regionally significant wetlands are present along the elbow around 9 km downstream of the intake. The Internationally significant Ramsar-listed Whangamarino wetland is located off the main stem of the Waikato River on the Whangamarino River and therefore well upstream of the intake. Water levels in the Whangamarino are also set by the Whangamarino Weir and would therefore be

Tonkin & Taylor Ltd 19 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd unaffected by downstream water levels in the Waikato River, except on the rare occasion that downstream river levels are very high.

Photograph 5.1: View looking downstream along the banks of the Waikato River looking downstream from the Waikato intake site. Buoy indicates the location of the current water intake.

Tonkin & Taylor Ltd 20 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd 6 Existing intake structure

This section describes the design of the existing intake structure including the design parameters used to minimise any potential impacts on the Waikato River fisheries. The results of impingement (capture on the screens) and entrainment (movement through the screens) and monitoring undertaken since the current intake was commissioned are outlined to demonstrate how effective the intake design has been in minimising impacts on fisheries. These data therefore inform our assessment of ecological effects for the proposed intake on the basis that the proposed screen parameters will be the same.

6.1 Existing intake design The design for the current Waikato intake was developed following a detailed literature review of available fish protection technology for water intakes undertaken by Boubee (1994). The current intake is designed with Johnson T-54 Passive Intake screens. The use of wedge wire screening material with low through-screen velocities acts to minimise potential for fish impingement. The screens are also designed to minimise entrainment of small animals and plants such as larval fish and algae. Key design parameters of the current intake include: i The current intake structure is located approximately 25 m off the true right bank and off the river bed, ensuring that passage along the banks and river bed for upstream migrants is not hindered; ii The screens are four Johnson T-54 Passive Intake screens with 1.5 mm slot widths consistent with WRP’s mesh size criteria, to minimise entrainment of fish; iii Screen through-slot velocities (approach velocities) are less than 0.15 m/s (thus less than WRP’s maximum intake velocity of 0.3 m/s), to minimise fish impingement on the surface of the screens; and iv To provide maximum protection water velocities parallel with the screen (i.e. the sweep velocity) are at least twice the approach velocity, to minimise both impingement and entrainment of fish.

6.2 Intake impingement and entrainment records Since the commissioning of the intake, Watercare has undertaken routine entrainment monitoring to assess the effectiveness of the intake screens and approach/sweep velocities to prevent the impingement and entrainment of fish eggs or larvae, which are known collectively as ichthyoplankton. Monitoring is undertaken in accordance with Watercare’s Fisheries Management Plan (T+T, 2007). As fish eggs and larvae are often smaller than the 1.5 mm mesh size, some entrainment does occur. The objective of the monitoring was to determine if entrainment was occurring at greater densities than would be expected within the river on average. If higher densities were being entrained it would indicate that the intake screens are located in a position where fish egg and larvae are at higher than average densities within the river. The monitoring that has been carried out at the Waikato intake is described below. Refer to Figure 6-1 for schematic of monitoring (T+T, 2007): · 2003 – present: Bi-annual dive surveys to assess screen condition, flow velocities and river bed levels at various points around the screens, accumulation of debris, and possible impingement of aquatic organisms on the screens;

Tonkin & Taylor Ltd 21 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd · 2004 – 2006: Four annual surveys (at night, during the winter spawning season) of native fish egg and larvae densities at three sites; one in the main river channel, one adjacent to the intake screens, and one in the penstocks of the WTP. These data give an indication of fish egg and larvae entrainment through the screens and a baseline dataset for more targeted monitoring from 2007 onwards; and · 2007 – present: Annual survey of native fish egg and larvae densities at one site in the penstocks of the WTP, with additional, more intensive, monitoring if trigger values (based on 2003 – 2006 river monitoring data) are exceeded. This has happened on two occasions, once in 2011 and again in 2017.

Figure 6-1: Entrainment monitoring sample sites. (P) = Penstocks, (S) = Screen sample, (1-9) = river sample sites5

6.3 Impingement and entrainment monitoring results Over the past sixteen years of bi-annual dive surveys no adult or juvenile fish have been found impinged on the intake screens. Figure 6-2 shows the average number of fish eggs and larvae per cubic metre of water flowing in the river compared to that abstracted into the intake per second, based on samples collected between 2004 and 2020. Data show that the proportion of fish egg and larvae being abstracted compared to the total passing downstream in the river is small.

5 Sites (S) and 1-9 are only monitored if densities in the Penstocks are elevated. During usual sampling procedures only site (P) in monitored.

Tonkin & Taylor Ltd 22 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Figure 6-2: Average number of fish eggs and larvae per cubic metre flowing down the river compared to that measured inside the intake penstocks between 2004 and 20206.

During the autumn 2011 fish eggs and larvae entrainment monitoring event, smelt larvae were detected in the penstocks of the WTP at levels slightly higher than the alert level set in the Fisheries Management Plan (T+T, 2007). Consequently, three additional surveys were undertaken in June 2011 to investigate entrainment of the total downstream ichthyoplankton migration. Smelt larvae were found in the penstocks area on 16 June (Survey 1) and 23 June (Survey 2) in very small numbers (1.04 % and 0.28 % entrainment respectively), but were absent on 30 June (Survey 3). Smelt larvae were found in the Waikato River on all three occasions. An average entrainment value of 0.44 % for smelt larvae compared to the larvae found in the river was calculated from the three June sampling rounds. This value is below the 2 % trigger value of the total downstream fish eggs and larvae migration estimated at the intake site as set out in Section 4.3.2 of the Waikato Intake Fisheries Management Plan (T+T, 2007). If this value had been exceeded it may have indicated that an elevated proportion of fish eggs and or larvae are being entrained through the intake screens. During the autumn 2017 fish eggs and larvae entrainment monitoring event, smelt larvae were again detected in the penstocks of the WTP at levels slightly higher than the alert level set in the Fisheries Management Plan (T+T, 2007). Consequently, three additional surveys were undertaken in June 2017, to investigate entrainment of the total downstream ichthyoplankton migration. Smelt larvae were found in the penstocks area and in the Waikato River on all three sampling runs. An average entrainment value of 12.73 % for smelt larvae compared to the larvae found in the river was calculated from the three June sampling rounds. This elevated entrainment result was due to higher numbers of smelt found in the wet well on one of the three sampling occasions. This value is

6 Data up to 2016 has been based on river mean flow of 407 m3/s and an abstraction rate of 0.464 m3/s as determined during the 2011 additional monitoring Data for 2017 was based on river mean flow of 407 m3/s and abstraction rate of 0.835 m3/s. Fish eggs and larvae numbers are based on yearly averages between 2004-2019.

Tonkin & Taylor Ltd 23 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd above the 2 % trigger value of the total downstream fish eggs and larvae migration estimated at the intake site as set out in Section 4.3.2 of the Waikato Intake Fisheries Management Plan (T+T, 2007). In summary, monitoring since the establishment of the Waikato intake has not recorded any impingement of aquatic organisms on the surface of the screens. Twenty-nine entrainment surveys carried out between 2004 and 2020 have shown that on average entrainment of fish eggs and larvae occurs at levels no greater than would be expected based on densities in the main river channel. The positioning of the intake screens has therefore been demonstrated to be appropriate, as the monitoring data show that the screens are not located in a position within the river where egg and larvae densities are greater than average.

Tonkin & Taylor Ltd 24 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd 7 Existing WTP discharges

Watercare monitors the quality of its discharges to the Waikato River for consent compliance purposes. Watercare also routinely undertakes a wider suite of testing on the raw water from the Waikato River including microbes, herbicides, nutrients, trace elements (total concentrations), trihalomethanes and volatile organic compounds (VOCs). As part of existing WTP operations, partially treated water is discharged to the Waikato River via the “off-spec” pipeline, which is connected to the downstream end of the intake structure when necessary. Potential discharge scenarios also arise where water from the WTP overflows from some latter compartments of the treatment process and can discharge into the unnamed tributary of the Waikato River. Discharges from the current WTP fall into one of three categories:

7.1 Quantity of the existing WTP discharges Watercare currently exercises a consent to discharge up to 20,000 m3/d of process water to the Waikato River (Table 7-1) under section 124 of the RMA. Watercare has applied for a replacement consent and it is anticipated this will have been issued by the time this application is heard by the Board of Inquiry. Between 2015 and 2019 the maximum daily planned discharge was 18,539 m3/d with an average maximum daily discharge of 7,416 m3/d. Watercare also has consent for unplanned discharges; between 2015 and 2019 the maximum unplanned discharge was 13,807 m3/d with a maximum discharge rate of 1.844 m3/s.

Tonkin & Taylor Ltd 25 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Table 7-1: Existing maximum discharge rates between 2015 and 2019 vs the proposed discharge rate

Existing discharge rate (existing Proposed discharge rate consent) (currently in draft conditions of replacement consent) Unit m3/day m3/s m3/day m3/s Discharges (consented maximum 20,000 2.45* 20,000 2.45* for process discharges) Discharges (actual maximum 18,539** 0.959* - - process discharge) * Maximum instantaneous rate ** The washwater recycled volume has been subtracted from the total process discharge to the off-specification pipeline and miscellaneous discharges have been added.

7.2 Quality of the existing WTP discharges Watercare test for a range of parameters in the water discharged back into the Waikato River. The following graphs present the monitoring data for some of the key parameters which have discharge quality limits as set out in Watercare’s resource consents. A review of discharge quality by T+T in 2016 (T+T 2016), noted that there were some exceedances of ANZECC guidelines7 for total phosphorus, nitrate, aluminium (total), copper and zinc in the discharge prior to mixing. These exceedances correlate with concentrations found in the raw water abstracted from the Waikato River and are not a result of the water treatment processes. Results from 2016 to 2020 as provided by Watercare are shown in Appendix C and show a similar pattern to that reported in 2016. The key water quality parameters affected by the treatment process are pH, soluble aluminium, total suspended solids (TSS), free available chlorine (FAC) and fluoride. Figure 7-1, Figure 7-2, Figure 7-3, Figure 7-4 and Figure 7-5 present discharge quality data collected by Watercare for each parameter over the past five years. Over this time there has been the occasional exceedance of consent limits for pH, soluble aluminium and TSS. These exceedances are reported by Watercare and where appropriate an Event Investigation Report prepared, procedures reviewed and results monitored.

7 Updated to the ANZ guidelines for freshwater and marine water quality (ANZG (2018). https://www.waterquality.gov.au/anz-guidelines/guideline-values/default/water-quality-toxicants/search

Tonkin & Taylor Ltd 26 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Figure 7-1: pH levels in the planned/process water discharges into the Waikato River between 14/04/2015 and 07/04/2020 (collected by Watercare) (Consent limits for pH of between 6 and 9 are shown as red lines (to be updated to between 6.5 and 9 in the proposed conditions for the Waikato WTP discharge consent)).

Figure 7-2: Soluble aluminium levels in the planned/process water discharges into the Waikato River between 06/01/2015 and 07/04/2020 (collected by Watercare) (Consent limit of 5 mg/L is shown as a red line (to be updated to 4 mg/L in the proposed conditions for the new Waikato WTP discharge consent)).

Figure 7-3: Total suspended solids (TSS) concentrations in the planned/process water discharges into the Waikato River between 16/06/2015 and 07/04/2020 (collected by Watercare) (Consent limit of 50 mg/L is shown as a red line and is included in the proposed conditions for the Waikato WTP discharge consent).

Tonkin & Taylor Ltd 27 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Figure 7-4: Free available chlorine (FAC) levels in the planned/process water discharges into the Waikato River between 14/04/2015 and 07/04/2020 (collected by Watercare)8 (Consent limit of 0.5 mg/L (to be updated to 0.25 mg/L in the proposed conditions for the new Waikato WTP discharge consent)).

Figure 7-5: Fluoride levels in the planned/process water discharges into the Waikato River between 16/06/2015 and 07/04/2020 (collected by Watercare) (Consent limit 2 mg/L).

7.2.1 Dimensions of the mixing zone There is currently limited information available to describe the mixing zone downstream of the existing Waikato WTP discharge point. A previous dye release study was undertaken by the National Institute of Water and Atmospheric Research (NIWA) for Watercare’s Pukekohe Waste Water Treatment Plant located approximately 11 km downstream of the Waikato WTP (T+T, 2017). The purpose of that study was to assist in understanding the mixing of discharges into the lower Waikato River (Hudson et al, 2016) associated with the Pukekohe Waste Water Treatment Plant. The results of the NIWA study suggest the dye plume attached to the true right bank in a relatively narrow plume as it flowed downstream (approximately 20 – 90 m wide) and that full mixing would not occur for some distance downstream (in the order of 1.1 km – 2.8 km downstream of the Pukekohe Waste Water Treatment Plant). It is important to note that the Pukekohe site is 11 km downstream of the intake site and therefore has a greater tidal influence than that at the Waikato WTP. It should also be noted the river splits into two at this location reducing mixing potential. Additionally, the dye was released near the bank rather than in the main river flow. All of these

8 Outlier of 54 mg/L removed (20/09/2016).

Tonkin & Taylor Ltd 28 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd factors indicate that the mixing zone indicated in the NIWA study is very conservative with respect to the proposed WTP discharge under this application. An important conclusion from the NIWA study with respect to existing and proposed WTP discharges is that the discharge plume would not affect the majority of the main river channel width therefore allowing fish (the most sensitive species in the river) to avoid the plume by moving across the channel if it was causing distress.

Tonkin & Taylor Ltd 29 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd 8 Assessment of ecological effects

This section identifies and assesses the water quality and river ecological effects that may arise from construction and operation of the intake structure, the proposed water take and proposed discharges. The methodology for undertaking this assessment is detailed in Section 4 and Appendix B. We note that while the EcIAG can be applied to determine ecological effects within the river, the guidelines are not necessarily applicable to determining effects on water quality. Actual and potential effects on river ecology have been identified as follows. Construction effects: · Effects on river water quality associated with sediment release and potential spills; · Effects on the river bed from piling and coffer dam activities; and · Effects on river freshwater biota associated with the piling and coffer dam activities; Operational effects of the water take along with effects associated with the screens and discharges: · Effects on river temperature and DO due to reduced flow in the Waikato River; · Effects on river water quality through routine cleaning of the intake screens; · Effect of the discharge on water quality and the ecology of the lower Waikato River: - Soluble aluminium; - FAC; - Glycerine; - Fluoride; and - TSS. · Effects on river freshwater biota and habitat through the abstraction of water and the operation of the intake screens including effects on: - River habitat; - Īnanga spawning habitat; - Upstream and downstream migration; - Fish, fish eggs and larvae impingement; - Fish eggs and larvae entrainment; - Riparian and wetland values; and - Disturbance due to intake screen cleaning.

8.1 Assigning ecological value When considering only native fish, the ecological value of the lower Waikato River would be considered Very High (Appendix B Table B.1). This is based on the habitat provided for a diverse range of native fish species, as well as a pathway for various species to migrate upstream and downstream to complete their lifecycles. Of the nineteen native fish species recorded in the lower Waikato River, two are considered to be ‘Threatened’ and eight are considered to be ‘At risk’ (Dunn et al., 2018). However, when assigning an overall ecological value to the lower Waikato River, there are a number of other factors that must also be taken into consideration. For example: · Macroinvertebrate communities recorded at WRC sites closest to the intake do not appear to contain taxa that are particularly sensitive to changes in water quality or habitat conditions;

Tonkin & Taylor Ltd 30 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd · Riparian vegetation is largely dominated by exotic species including willows and alder; and · Water quality is noted as “Unsatisfactory” for some key parameters such as total phosphorus and turbidity. When taking all these factors into consideration, for the purpose of this assessment we have considered the lower Waikato River as being of High ecological value. High value is representative of a watercourse with high ecological or conservation value, but which has been modified through loss of riparian vegetation, fish barriers, and stock access or similar, to the extent it is no longer reference quality (Roper-Lindsay et al, 2018). There is slight to moderate degradation, e.g. exotic forest or mixed forest/agriculture catchment. For the purpose of this assessment the wetlands located approximately 13 km downstream of the intake have been valued separately to the lower Waikato River. Given the presence of Nationally and Regionally significant wetlands (van der Zwan and Kessels, 2017), these have specifically been given an ecological value of Very High. The very high value is due to the likely presence of range of Threatened and At Risk birds and fish along with the potential īnanga spawning habitat (Envirostart Consulting Ltd, 2018; van der Zwan and Kessels, 2017).

8.2 Construction effects

8.2.1 Effects on river water quality The main potential for adverse water quality effects relates to elevated suspended sediment and reduced clarity immediately downstream of the pile and coffer dam locations due to disturbance of the river bed during construction. It is proposed to install up to nine permanent piles as part of the intake structure. The number of temporary piles associated with the temporary access platform (temporary staging area) is still to be confirmed. A temporary coffer dam will also be installed near the river bank to allow the tunnel boring machine (TBM) to be removed after drilling from the pump station site towards the river. There is the potential for bed disturbance through both the piling and installation of the cofferdam as well and removal of these temporary structures. Some bed disturbance and temporary sediment discharges will be unavoidable during this process. However, this will be localised and short term in nature (approximately one day for each pile and 2 weeks for the coffer dam). Removal of the temporary structures is proposed to occur over a three month period. As the bed of the Waikato River at the intake site is dominated by sand and pumice (which is constantly moving), it is not anticipated that there will be a significant amount of sediment released and subsequently any adverse effects on water quality are expected to be temporary and negligible in nature. Sediment disturbance and temporary sediment discharges will be limited to the period of the works and shortly after (hours) and may result in a slight reduction in clarity within the mixing zone to conditions similar to or less than what would occur during flood flows, which can reach up to 100 mg/L for total suspended solids and 84 NTU for turbidity (refer to total suspended solids and turbidity data presented in Section 5.1). Additional temporary disturbance of a similar scale will also occur at the time temporary piles and coffer dam are removed. Additional to sediment release there is also the risk to water quality through any accidental spills associated with concrete (used during the construction of the permanent piles) and diesel or hydraulic fluid used during the construction works. In order to minimise the potential for adverse water quality effects associated with construction, a coffer dam will be installed at the tunnel portal to allow work within the vicinity to be undertaken in the dry and isolated from the river. During the temporary and permanent pile works in the river it is recommended any water contaminated with cement is not discharged directly into the river as this can negatively effect pH levels. It is also recommended appropriate emergency spill kits are held on site.

Tonkin & Taylor Ltd 31 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Overall, the potential magnitude of effect from the construction of the intake on river water quality is considered to be Negligible resulting in an overall Very Low9 level of effect.

8.2.2 Effects on the river bed A contractor has confirmed that approximately 760 mm (diameter) of the river bed will be disturbed at each permanent pile location with the temporary piles being slightly smaller at 710 mm (diameter). The piles for the new intake will be located at various locations adjacent to or downstream of the existing intake. The pilling work requires installation of up to nine permanent piles resulting in approximately 760 mm (diameter) of bed disturbance (i.e. approximately 4 m2 in area, 0.45 m2 per pile)10. For the purpose of this assessment, it has been assumed an area of 200 m2 will be occupied by permanent works (manifold and pipework). This is conservative as the river bed will not be directly effected over that whole area. Instead permeant river bed loss will only occur where the structures are located on the river bed, which as noted above will equate to approximately 4 m2. Temporary construction effects include the installation of the sheet pile coffer dam resulting in the temporary disturbance to an approximately 240 m2- of river bed. The total area of bed disturbance associated with the temporary piles has yet to be confirmed however it is estimated approximately 20 piles would be installed. This would result in a small in scale disturbance of approximately 8 m2 in area, 0.4 m2 per pile. River bed habitat disturbance during the temporary works will therefore be approximately 248 m2 in total. The piling itself will be short-term in duration (approximately one day for each pile), however, the duration of the temporary works will be approximately three months and permanent works carried out over a 15 month period. Conservatively it has been assumed some degree of intermittent bed disturbance could occur over this duration within the vicinity of the project footprint. The temporary piles and cofferdam are anticipated to be in place for approximately 21 months including a three month period over which the temporary piles would be removed. Following the removal of the temporary piles and coffer dam it is anticipated the river bed will reform and any habitat is expected to quickly return to its pre-works condition. In summary the permanent river bed disturbance due to occupation by permanent structures as part of the proposal would be small and localised in extent (approximately 200 m2 in total of which 4 m2 will be permanent loss of river bed habitat). During construction there will be additional areas of temporary bed disturbance (approximately 248 m2) over a 21 month period (ref Appendix B Table B.3). Overall the potential magnitude of effect from the construction of the new intake on the river bed is considered to be Low due to only a minor shift away from existing baseline conditions (ref Appendix B Table B.2) resulting in an overall Low9 level of effect.

8.2.3 Effects on river freshwater biota Bed disturbance works and the water quality effects described in the previous sections can impact on river fauna through reduced water clarity for visual feeders (trout), sedimentation to the bed of the river and associated habitat quality effects, direct disturbance to benthic habitats, and disruption to fish passage and upstream migrating fish species. Effects on water clarity and sedimentation will be localised and temporary (section 8.3.3.5) with no lasting adverse effects on trout habitat or benthic habitat quality anticipated. Direct impacts on benthic habitats and associated macroinvertebrate communities within the footprint of the piles will be unavoidable. The total scale of disturbance is estimated to be 740 m2.

9 As determined using the matrix presented in Appendix A Table 4. 10 Subject to detail design.

Tonkin & Taylor Ltd 32 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd This area includes both the area of temporary bed disturbance (approximately 240 m2), permanent bed disturbance (approximately 200 m2 of which 4 m2 would be river bed habitat loss) and the area of which a work platform will be positioned above the water surface potentially reducing the level light infiltration into the river (approximately 300 m2 including 8 m2 of river bed loss associated with the temporary piles). Existing data suggested macroinvertebrates communities within the Waikato River are characterised by species typically found in soft bottom environments that are not particularly sensitive to changes in water quality or habitat disturbance and availability. Due to the small scale (area of ground disturbance) and temporary nature of the proposed works it is not anticipated that any changes to macroinvertebrate communities would occur beyond the area of immediate disturbance. A range of native fish (and trout) will almost certainly be present within or migrate through the river past the site, several of which are classified as At Risk or Threatened. When all of these species are considered together, the peak migration seasons cover most of the year and can therefore not be avoided. However, the works area within the water column and river bed will be small relative to the size of the Waikato River and as a result fish passage will be maintained within the river at all times during the construction activities. While there may be some avoidance of the specific construction locations, fish can make their way past while avoiding this area. Bank conditions near the current intake are characterised by natural rock walls and fast moving currents thus the site is naturally not ideal for fish migration (banks with low velocities and shelter are preferred). River currents and turbulence around the cofferdam are expected to increase during the construction period. This may lead to fish avoidance of this area by smaller fish with poor swimming ability over this time. This effect is expected to be temporary and fish are expected to find other areas to migrate past the coffer dam such as further out in the river or along the opposite bank were bankside vegetation currently provides for comparatively low velocity areas. Overall, the potential magnitude of effects from the construction of the new intake on river freshwater biota are Low due to only a minor shift away from existing baseline conditions (ref Appendix B Table B.2) resulting in an overall Low9 level of effect.

8.3 Operational effects

8.3.1 Effects on river temperature and dissolved oxygen due to reduced flow in the Waikato River In order to determine the effects of the proposed abstraction on temperature and dissolved oxygen (DO) levels in the river, the computer software SEFA (System for Environmental Flow Analysis) has been used. SEFA implements the River Flow Incremental Methodology (IFIM) to provide a set of tools that allow the effects of flow alteration on various physical parameters to be assessed. For the purpose of this assessment we have modelled a summer scenario (late February early March) assuming a cumulative effect of the existing abstraction of 150,000 m3/day (net) plus the additional 150,000 m3/day (net) applied for as part of this application at a maximum combined rate of 5.65 m3/s.

8.3.1.1 Methods The following section outlines methods carried out to assess changes in temperature and DO within the Waikato River as a result of the proposed take. Modelling has been carried out based on flow and cross-sectional data at the flow recording site at Mercer, sourced from WRC at the time water quality datasondes were deployed (i.e. between 23 February 2013 and 3 March 2013). Due to drought in the Waikato catchment at this time the river was in low flow condition. River levels in the summer of 2013 were the lowest compared with that recorded in the following seven years including flows in 2020.

Tonkin & Taylor Ltd 33 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd The Mercer river cross-section has been used as it is the closest recorded upstream cross-section to the Waikato intake with river flow information. The distance between Mercer and the Waikato intake is approximately 6 km. Over this section of river, additional catchment inflows on average is approximately 3 m3/s (at MALF). Consequently, modelling results based on a cross section at Mercer are conservative. It is proposed to update the 2013 data with supplementary information collected during the 2021 summer depending on drought conditions in the river (i.e. if conditions were similarly low to those experienced in 2013 which reflects a worst case scenario).

8.3.1.1.1 Temperature model A water temperature model11 has been developed using water temperature data collected at Mercer and at the Waikato intake between 23 February 2013 and 3 March 2013. Water temperature was recorded at three sites. Two datasondes were deployed one approximately 30 m upstream of the Waikato intake and the other downstream of the intake below the Tuakau Bridge. Datasondes were calibrated to the manufacturer’s specifications. Both datasondes were deployed on the true right bank of the Waikato River. Datasondes were programmed to log temperature, DO and pH at 15 minute intervals. Upstream at Mercer a TidbiT temperature logger was deployed recording temperature every 15 minutes. Water temperatures recorded by the datasondes and the TidbiT logger were checked against spot measurements of river temperature taken with a calibrated meter (ProDO DO meter and Eutech pH pen) when the recorders were installed and removed. The recorders were also immersed in a bucket of water prior to and following deployment with readings of the meter and all temperature recorders noted. A temperature adjustment of +0.18 °C has been made to the intake temperature record to calibrate it with the meter and the temperature recorder at Mercer. Climate data12 for the corresponding period from the automatic weather station at Pukekohe has also been used to calibrate the model. The river cross-section at Mercer was used to obtain average water depth and velocity for the flows recorded at Mercer between 23 February 2013 and 3 March 2013. The calibrated model assumed a shade factor of 0.2, wind reduction of 1, and bed conductivity of 31.8 J/m/s/C. Predicted daily mean water temperature was within 0.04 °C (Figure 8-1) and daily maximum water temperature within 0.27 °C of water temperatures recorded at the Waikato intake (Figure 8-2), validating model calibration.

11 Lagrangian model described in Rutherford, J. C.; Blackett, S.; Blackett, C.; Saito, L.; Davies-Colley, R. J. 1997. Predicting the effects of shade on water temperature in small streams. New Zealand Journal of Marine and Freshwater Research 31: 707-721. 12 Surface wind, temperature, earth temperature, radiation, relative humidity and sunshine hours.

Tonkin & Taylor Ltd 34 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Figure 8-1: Comparison of measured “corrected” and predicted daily mean water temperatures at the Waikato intake.

Figure 8-2: Comparison of measured, "corrected" and predicted daily maximum water temperatures at the Waikato intake.

8.3.1.1.2 Dissolved oxygen model Measurements of DO concentration and water temperature at the Waikato intake (Figure 8-3) were used to calculate the DO parameters (re-aeration coefficient (/d), daily respiration rate (mg/L/d), ratio of production to respiration (P/R), and the ratio of respiration rates 10 °C apart) that gave the best fit to measured DO concentrations for each day between 23 February 2013 and 3 March 2013.

Tonkin & Taylor Ltd 35 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Figure 8-3: Measured water temperature and DO concentration at the Waikato intake and river flow at Mercer.

8.3.1.2 Results

8.3.1.2.1 Temperature model The water temperature model has been used to predict the effect of the Watercare abstraction on water temperature 10 km downstream (Tuakau) and 20 km downstream (Port Waikato) of the proposed abstraction, with flow and the climatic conditions that prevailed during late February to early March 2013. February and March conditions represent a time of highest temperatures and stable low flows and is therefore indicative of conditions at which the abstraction is likely to have its greatest impact. Results showed that the maximum change in daily mean water temperature would be a reduction of less than 0.02 °C, both 10 and 20 km downstream of the intake (Table 8-1). The maximum change in maximum daily water temperature varied between +0.02 °C and –0.04 °C. Water temperature is largely dependent on weather conditions. Overall, the changes in temperatures shown through this model are small indicating the abstraction will have little effect on water temperatures. The river is influenced by the tide between the intake and estuary. At high tide the river water velocity would be lower and depth greater compared to conditions at low tide. A reduction in depth would increase daily maximum water temperature, so that if high tide occurred near midday, the predicted change in maximum water temperature would be slightly less than predicted and vice- versa at low tide. An increase in velocity would decrease the change in mean water temperature, so that at high tide the change in mean temperature would be slightly greater and at low tide slightly smaller. Overall, variations in tidal effects and average water depths and velocities do not alter the conclusion that abstraction of an additional 150,000 m3/day net will have a negligible effect on water temperature.

Tonkin & Taylor Ltd 36 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Table 8-1: Predicted change in downstream water temperature resulting from Watercare’s existing and proposed abstractions.

Date Water Flow Change in water Change in water Change in water temp at just temperature with temperature with temperature with intake above existing maximum proposed additional proposed (°C) intake abstraction (150,000 abstraction (150,000 combined (m3⁄s) m3/day net at a rate of m3/day net at a rate of abstraction 2.45 m3⁄s) 3.2 m3⁄s) (300,000 m3/day net at a rate of 5.65 m3⁄s) Daily Daily max Daily Daily max Daily Daily mean mean mean max 10 km downstream of the intake 23⁄2⁄13 23.224 193.359 0.000 -0.001 0.000 -0.002 -0.001 -0.003 24⁄2⁄13 23.484 195.516 -0.001 -0.001 -0.001 -0.001 -0.001 -0.002 25⁄2⁄13 23.364 198.407 0.000 -0.001 0.000 -0.002 -0.008 -0.020 26⁄2⁄13 23.248 204.743 -0.001 -0.001 -0.001 -0.001 0.000 -0.002 27⁄2⁄13 23.263 210.498 -0.007 -0.019 -0.007 -0.019 -0.006 -0.018 28⁄2⁄13 22.785 218.576 0.000 -0.001 0.000 -0.001 -0.001 -0.001 1⁄3⁄13 22.574 231.433 -0.005 -0.017 -0.006 -0.018 -0.002 -0.002 2⁄3⁄13 22.661 221.285 0.000 0.000 0.000 0.000 -0.002 -0.002 3⁄3⁄13 22.606 215.085 -0.001 -0.001 -0.001 -0.001 -0.001 -0.001 20 km downstream of the intake 23⁄2⁄13 23.224 193.359 -0.001 -0.002 -0.007 -0.029 -0.008 -0.032 24⁄2⁄13 23.484 195.516 0.000 -0.003 -0.001 -0.004 -0.007 -0.035 25⁄2⁄13 23.364 198.407 -0.007 0.004 -0.007 0.004 -0.008 0.005 26⁄2⁄13 23.248 204.743 0.000 0.001 -0.005 0.015 -0.005 0.016 27⁄2⁄13 23.263 210.498 -0.006 -0.026 -0.006 -0.027 -0.006 -0.027 28⁄2⁄13 22.785 218.576 0.000 0.001 -0.004 0.007 -0.004 0.008 1⁄3⁄13 22.574 231.433 -0.007 -0.024 -0.008 -0.024 -0.009 -0.026 2⁄3⁄13 22.661 221.285 -0.001 -0.002 -0.002 -0.003 -0.012 -0.030 3⁄3⁄13 22.606 215.085 0.000 0.001 0.000 0.001 -0.001 0.002

8.3.1.2.2 Dissolved oxygen model Model results showed that minimum DO concentrations decreased linearly with flow, with a DO reduction of 0.00046 mg/L for each m3/s reduction in flow using parameters measured on 23/2/2013, and a DO reduction of 0.00015 mg/L per m3/s of flow reduction using median parameters (Figure 8-4). The predicted reduction in minimum DO resulting from the baseline current abstraction of 150,000 m3/day net and an additional 150,000 m3/day net are less than 0.0011 and 0.0024 mg/L, respectively. The additional abstraction will therefore likely result in a reduction in DO of approximately 0.0015 mg/L, which would not be measurable and would not result in an adverse ecological effect.

Tonkin & Taylor Ltd 37 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Figure 8-4: Comparison of measured and predicted DO concentration at the Waikato intake for the 9 days 23/2/2013 to 3/3/2013 using median DO parameters.

8.3.1.3 Summary The lower Waikato River is considered to be of High ecological value. Modelling indicates the magnitude of the effect from the reduction of flows in the Waikato River by both 150,000 m3/day net and Watercare’s proposed additional 150,000 m3/day net will result in negligible changes to temperature and DO concentrations 10 to 20 km downstream of the intake. Changes will not be within the resolution of most data recorders, at less than 0.02 °C and less than 0.01 mg/L, and will therefore be largely undetectable. Although seven years old, data collected in 2013 is representative of a summer where flows were at their lowest in the Waikato River over the seven year period and is therefore still considered relevant to this assessment. It is proposed to collect additional temperature and DO data in the summer of 2021 if flows are lower or similar to those in 2013 to validate that this information is still applicable to current conditions in the Waikato River. While the lower Waikato River is considered to be of High value, the magnitude of the changes to temperature and DO as a result of the proposed increase in take at the Waikato intake is considered to be Negligible. Overall, the potential overall level of ecological effect from the change in temperature and DO is considered to be Very Low9.

8.3.2 Effects on river water quality through routine cleaning of the screens Cleaning of the intake screens mobilises organic (algal) material into the water column of the lower Waikato River. The mobilising of screen detritus has the potential to affect water clarity through the suspension of algae / organic material present on the intake screens. For the purpose of this application the use of a brush screen and sparging have been considered with an effects assessment provided for each. The existing intake screens have been designed to permit back flushing by air “sparging”. In 2016 an assessment of the effects associated with the sparging of the existing Waikato WTP screens was undertaken by T+T (T+T, 2016). As part of this assessment TSS and chlorophyll a concentrations in samples were collected from the Waikato River pre and post sparging. The assessment indicated that sparging resulted in an observable change in water colour near the intake screens immediately after sparging was carried out. Statistical analysis showed that the sparging of Screen 4 had no effect on chlorophyll a concentrations at the surface of the river 20 m downstream of the intake screens, suggesting that

Tonkin & Taylor Ltd 38 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd any potential increase in chlorophyll a concentrations due to the sparging had mixed completely within the river at that point. TSS levels were also similar pre and post screen sparging and phaeophytin a13 concentrations were nearly all below laboratory detection pre and post sparging. While the lower Waikato River in the vicinity of the existing and proposed intake screens is considered to be of high value, the lower river is known to have water clarity issues, with both five year turbidity and water clarity measurements falling within the WRC ‘unsatisfactory’ category. The magnitude of any potential effect on water clarity associated with the cleaning of the screens is considered to be negligible based on previous assessments of the existing sparging process. The brush cleaning process would not result in such an instantaneous discharge as what would be observed for the sparge cleaning process. Instead the screens would rotate one clockwise rotation and one anti-clockwise cycle at pre-set intervals. The number of cycles per day may vary depending on debris load in the river but are anticipated to typically occur once a day. The slower release relative to the sparging means the mobilised material can quickly be mixed with the river water with the material being detritus which is already conveyed by the river. It has been noted in the Waikato River Take – Waikato Intake Feasibility Report (GHD, 2020) that the proposed brushed screens would be rotated using either electric or hydraulic motors. Under the hydraulic motor scenario it is proposed food grade hydraulic oil would be used for the hydraulic system to mitigate the effect of any accidental oil spill. Any maintenance work could be undertaken above water level, using extendable lengths of hydraulic hose. If a spill occurs it is expected that this would be short term and of minimal quantity due to the relatively small diameter hoses used and therefore volume of oil in the system. Additional to this, emergency shutdown measures can be included within the hydraulic system to minimise the extent of any spill (e.g. system isolation due to loss of hydraulic pressure). Under the electric scenario there would not be any use of hydrologic fluids and therefore any risks of spills. Overall, the potential magnitude of effect from the cleaning of the screens either using the sparging or brush screen arrangement during operation the intake on river water quality are Negligible resulting in an overall Very Low9 level of effect.

8.3.3 Effect of the WTP discharge on water quality and the ecology of the lower Waikato River The potential for effects from the Waikato WTP discharge is likely to be greatest at the point of discharge into the Waikato River where little / no dilution would have occurred. The predicted maximum concentrations of the specific parameters that are will be discharged are presented in Table 8-2 below, along with the maximum recorded concentrations in the receiving waters and relevant receiving environment water quality guidelines.

Table 8-2: Comparisons between river water quality, proposed discharge quality and appropriate receiving environment guidelines after reasonable mixing.

Parameter Units Maximum Proposed Receiving environment guidelines concentration in maximum after reasonable mixing Waikato River concentration in (2015 – 2020)* discharge (prior to mixing) Aluminium (Total) mg/L 3.4 4.0 0.055 – ANZG (2018).

13 Phaeophytin is one of the breakdown products of Chlorophyll.

Tonkin & Taylor Ltd 39 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Parameter Units Maximum Proposed Receiving environment guidelines concentration in maximum after reasonable mixing Waikato River concentration in (2015 – 2020)* discharge (prior to mixing) FAC mg/L - 0.25 0.003 - ANZG (2018) (chronic) (trigger value for a 95% level of protection). 0.019 - USEPA acute guideline (1-hour maximum value) for the protection of aquatic species. Glycerine mg/L - 10 250 - (OCED Screening Information Dataset (SIDS) - UNEP PUBLICATIONS (CAS ID number 56-81-5)) pH pH 6.6 - 8.214 6.5 - 9 6.5 – 9 / 7.0 – 8.0 – WRC guideline (Satisfactory / Excellent values) TSS mg/L 100 50 WRC - The activity or discharge shall not increase the concentration of suspended solids in the receiving water by more than 10 percent Fluoride mg/L 0.2 2 5.14 - Camargo (1996) * Watercare raw water quality data 2015 - 2020 The following sub-sections provide an assessment of the magnitude and overall level of effect for each key parameter in the proposed discharge. As noted in Section 7.2.1 there is currently limited information on the mixing zone downstream of the existing Waikato WTP discharge point. The estimated 1.1 to 2.8 km is highly conservative and contaminants in the proposed discharge are likely to be fully mixed over a much shorter distance. We have therefore used a basic calculation to assess potential concentrations in the Waikato River downstream of the discharge under various mixing / dilution scenarios for key contaminants such as FAC.

8.3.3.1 Soluble aluminium Naturally-occurring aluminium concentrations in Waikato River water (without the addition of the Waikato intake discharges) exceed relevant guideline values. Gensemer and Playle (1999) provide a detailed summary of aluminium toxicity to various aquatic organisms. Among freshwater aquatic plants, single celled plants (algae) are generally the most sensitive to aluminium. In terms of freshwater fauna, fish are generally more sensitive to aluminium than aquatic invertebrates. Aluminium is a gill toxicant to fish, causing both ionoregulatory and respiratory effects at low pH levels (<6.0) (Gensemer and Playle, 1999). Bioavailability and toxicity of aluminium is determined primarily by solubility, which is generally greatest in acidic solutions but also increases in strong alkaline conditions. The ANZG (2018) provide a moderate reliability 95% trigger value of 0.055 mg/L for aluminium at pH > 6.5 in freshwaters. A low reliability 95% trigger value of 0.0008 mg/L is provided at pH < 6.5. These figures are based on the results of toxicity tests (LC50) on freshwater animals and algae. Dissolved aluminium is generally at lower concentrations in water of neutral pH due to its insolubility at this pH range (Quiroz- Vázquez, 2010).

14 Outlier of pH 10.5 removed (24/01/2018)

Tonkin & Taylor Ltd 40 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd The toxicity of dissolved aluminium to aquatic life is highest through a pH range of 4.4 – 5.4 (ANZG, 2018). The median pH value (7.5) and the range of pH values from Watercare’s Waikato raw river water dataset (6.6 – 8.2) is therefore outside of the range of concern. Where pH of natural waters is outside this low pH toxicity range, river values (including fish and invertebrate diversity) would tend to be limited due to pH in any event, and environmental sensitivity reduced (Auckland Council, 2004). The discharge dissolved aluminium levels will remain below the proposed concentration limit of 4 g/m3. As a result of this and the pH levels in the discharge and the Waikato River receiving environment, dissolved aluminium is unlikely to have potential for toxicity effects on aquatic life beyond the mixing zone. Overall, the potential magnitude of effect from dissolved aluminium in the discharge on aquatic life is Low within the mixing zone resulting in a Low level of effect and Negligible outside the zone of reasonable mixing resulting in a Very Low9 level of effect.

8.3.3.2 Free available chlorine (FAC) Chlorine is added as part of the drinking water treatment process to help disinfect the water. The existing discharge consents require Watercare to test for the total residual chlorine (TRC) present in the discharge. The concentration of TRC present in water consists of FAC, as well as combined chlorine (i.e., chlorine that has chemically reacted with inorganic and organic compounds, such as ammonia). FAC is the most toxic component of TRC in terms of effects on aquatic organisms. The proposed consent limit for chlorine15 in water discharged back into the Waikato River is 0.25 mg/L. Relevant guidelines for an assessment of ecological effects associated with FAC, are as follows: · ANZG (2018) (chronic) guideline of 0.003 mg/L (trigger value for a 95 % level of protection); and · USEPA acute guideline (1-hour maximum value) for the protection of aquatic species 0.019 mg/L. In order to assess potential effects associated with FAC we have undertaken some basic calculations to assess potential concentrations in the Waikato River downstream of the discharge under various mixing / dilution scenarios. These calculations are summarised in Appendix D and assume dilution only, with no degradation of the discharged FAC and a concentration of zero in the Waikato River upstream of the discharge point, i.e. very conservative assumptions. The two scenarios assessed are as follows: · The chronic effects assessment scenario is represented by a discharge with a median FAC concentration (0.03 mg/L) and upper non-outlier range (0.8 mg/L) and a discharge rate of 0.722 m3/s (it has been assumed that the median discharge rate for the new plant will be the same as the existing plants median discharge rate16); and · The acute effects scenario is represented by the maximum proposed FAC concentration of 0.25 mg/L at the maximum discharge rate of 2.45 m3/s. For a chronic effects scenario, the calculations show that for a median FAC concentration, dilution with 3.2 % of the q5 low flow in the Waikato River is required to meet the ANZG (2018) 95 % protection trigger level. Dilution with 9.1 % of the q5 flow is required to reduce the FAC

15 TRC tested by Watercare as FAC primarily because FAC can be tested for in the field with handheld equipment, which means corrective actions can be undertaken more quickly. 16 As provided by Watercare summarising discharges between 2015 and 2020 at the existing water treatment plant.

Tonkin & Taylor Ltd 41 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd concentration to the ANZG (2018) 95 % protection trigger level at the upper non-outlier range of FAC discharge data (0.8 mg/L). For an acute scenario (maximum FAC and discharge rate), the relevant guideline would be achieved when the discharge was fully mixed with 15.6 % of the q5 flow. Overall, the calculations demonstrate that “normal” discharges need to fully mix with 6 to 17 m3/s 3 (e.g. 3.2 to 9.1 % of the q5 flow (185.9 m /s)) of Waikato River water to meet guideline levels for FAC (assuming median discharge rate of 0.722 m3/s). For the maximum concentration and discharge scenario mixing with 29 m3/s of Waikato River water is needed to meet guideline levels. In 2017 Watercare completed bench testing (Appendix E) of chlorine levels. The bench testing exercise was undertaken using samples of raw water spiked with chlorine with testing over time to monitor FAC degradation. Results showed that FAC reduced quickly (mostly within 1 minute) and to background concentrations within 4 to 10 minutes depending on the initial concentration. This indicated rapid degradation of FAC levels over time. Based on measured degradation within 1 minute and measured average velocities at the existing screens (generally around 1 m/s), it was determined that the actual mixing zone within which concentrations exceed background is expected to be no more than 60 m. The likelihood that FAC from the discharge would affect aquatic organisms within the mixing zone would be influenced by the following factors: · The stability of FAC in natural water is very low, due to chlorine being a strong oxidising agent, rapidly reacting with inorganic and organic compounds. As such, it is likely that the FAC from the discharge would break down quickly, reducing the likelihood of the FAC having an effect on aquatic organisms; · Temperature influences the toxicity of FAC, with toxicity reducing in warmer water temperatures (ANZG, 2018). This suggests that under qs flow conditions, when water temperatures could be expected to be warmer due to dry summer conditions, FAC toxicity would be further reduced; · Aquatic organisms (in particular fish) would be expected to show avoidance behaviour if FAC levels were causing stress and could move away to avoid the discharge point; and · Any FAC discharge at the maximum concentration would likely be for short duration. FAC is unlikely to have an effect on aquatic life after reasonable mixing. When the factors that influence FAC toxicity are considered alongside the natural avoidance behaviours of mobile aquatic life, it is considered that the magnitude of the effect on aquatic life is Low within the mixing zone resulting in a Low9 level of effect and Negligible outside the zone of reasonable mixing resulting in a Very Low9 level of effect.

8.3.3.3 Glycerine New membrane filter modules for the Waikato WTP arrive on site stored in glycerine. Glycerine is purged from the modules before they are added to service with the majority of the glycerine disposed of offsite. Once the concentration of glycerine remaining in the modules (measured as COD) is below 10 g/m3 the contents are discharged to the Waikato River. As such, the discharge of glycerine from Waikato WTP will only occur as new water filter modules are installed. Although no monitoring data are available, it is likely that the concentration of glycerine in the Waikato River upstream of the Waikato WTP would be zero.

Tonkin & Taylor Ltd 42 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd The glycerine discharge concentration will be well below the lowest eco-toxicity value for glycerine, 17 3 where a LC0 value (i.e. no deaths of fish recorded) of 250 g/m was determined (CAS ID number 56- 81-5). As a result, glycerine will have no effect on aquatic life. Overall, the potential magnitude of effect from glycerine on aquatic life is Low within the mixing zone resulting in a Low level of effect and Negligible outside of the zone of reasonable mixing resulting in a Very Low9 level of effect.

8.3.3.4 Fluoride Of the species present in the Waikato River, fish are likely to be the most sensitive species to fluoride in the discharge. Research into fluoride toxicity using acute mortality data has calculated safe concentrations of fluoride for trout species (Camargo, 1996). The calculated estimated safe concentration (infinite hour LC0.01 value) of fluoride for rainbow trout fry (8 – 10 cm long) in soft water (21.2 – 22.4 mg CaCO3/L) was 5.14 mg/L (approximately 2.6 times the proposed consent limit). Camargo (1996) also noted that bioavailability of fluoride ions is reduced with increased hardness. Watercare data show the median hardness of the Waikato River near the point of discharge was 30 g/m3, which would therefore further reduce any potential for adverse effects to occur to fish within the mixing zone. Overall, the potential magnitude of effect from the fluoride concentrations on aquatic life is Negligible inside and outside of the mixing zone resulting in a Very Low9 level of effect.

8.3.3.5 Total suspended solids The maximum level of TSS in the existing WTP discharge and what is expected in the discharge as part of this application is lower than the maximum recorded concentration recorded in the Waikato River. Therefore, the maximum discharge value for TSS is likely to be well within the natural levels experienced by the river and therefore would be unlikely to have an effect on aquatic organisms at the point of discharge. Median TSS concentrations within the process water discharges between 2015 and 2020 from the existing WTP was 7.4 mg/L while the median concentration in water from the Waikato River was 18.5 mg/L. This indicated that discharge will typically have lower TSS concentrations than that in the river. Overall, the potential magnitude of effect from the TSS on aquatic life is Low within the mixing zone resulting in a Low level of effect and Negligible outside the zone of reasonable mixing resulting in a Very Low9 level of effect.

8.3.3.6 Potential cumulative effects It is possible the discharges from the proposed Waikato A WTP could occur at the same time as any consented planned or unplanned discharges from the existing Waikato WTP. Therefore in order to understand worst case scenario cumulative effects, particularly in regard to FAC, we have repeated the basic mixing calculations to assess potential concentrations in the Waikato River downstream of the commissioning discharge under various mixing / dilution scenarios. We have focussed on FAC because of all the parameters FAC is the most toxic in terms of effects on aquatic organisms. In order to understand the cumulative effect of the proposed discharge combined with the effects of the existing discharge we have based the discharge rate on a combination between the proposed and consented planned discharges. These calculations are summarised in Appendix D and assume dilution only, with no degradation of the discharged FAC and a concentration of zero in the Waikato River upstream of the discharge point, i.e. very conservative assumptions. The two scenarios assessed are as follows:

17 Highest concentration of a substance in an environmental medium that does not cause death of test organisms or species.

Tonkin & Taylor Ltd 43 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd · The chronic effects assessment scenario is represented by a discharge with a concentration of FAC at the median FAC concentration (0.03 mg/L) and upper non-outlier range (0.8 mg/L) and a discharge rate of 1.44 m3/s (it has been assumed that the median discharge rate for the new plant will be the same as the existing 0.722 m3/s18 therefore resulting in a combined median intake rate of 1.44 m3/s); and · The acute effects scenario is represented by the maximum proposed FAC concentration of 0.25 mg/L at the maximum combined discharge rate of 4.9 m3/s (2.45 m3/s combined with 2.45 m3/s). For a chronic effects scenario, the calculations show that for a median FAC concentration, dilution with 5.9 % of the q5 low flow in the Waikato River is required to meet the ANZG (2018) 95 % protection trigger level under median discharge rates. Dilution with 17.2% of the q5 flow is required to reduce the FAC concentration to the ANZG (2018) 95% protection trigger level at the upper non- outlier range of FAC discharge data (0.8 mg/L). For an acute scenario (maximum FAC and maximum discharge rate at both WTP), the relevant guideline would be achieved when the discharge was fully mixed with 31.2 % of the q5 flow. It should be noted that this value is very conservative. In reality a maximum FAC would rarely coincide with the maximum discharge rate and even less likely to coincide with q5 flow conditions. Additional to this, the assumptions used in this calculation are very conservative by not accounting of the level of FAC degradation that would occur rapidly the river. Overall, our assessment indicates that FAC is unlikely to have an adverse effect on aquatic life after reasonable mixing. When the factors that influence FAC toxicity are considered alongside the natural avoidance behaviours of mobile aquatic life, it is considered that the magnitude of the effect on aquatic life from a cumulative perspective is Low within and beyond the mixing zone resulting in a Low9 level of effect.

8.3.4 Effects on river freshwater biota through the abstraction of water and operation of the intake screens

8.3.4.1 Effects on river habitat River flow regimes are one of the driving forces for river habitat availability and quality. Water flow supports the respiration of invertebrates and reproduction of some fish species. Aquatic life in streams and rivers such as the Waikato River are adapted to the ‘natural’ flow regime which includes periodic disturbances such as floods or droughts. Changes to the flow regime can have negative effects on river ecology by changing currents, reducing available instream habitat and altering water quality such as temperature and dissolved oxygen. River aquatic habitat includes river bank margins, river vegetation and river bed substrates. Fish and invertebrates are found in a wide range of aquatic habitats with many species having preferences for certain conditions. Water abstraction can affect the frequency of floods and the duration and magnitude of low flow. An assessment of the effects on river habitat has been carried out by determining the degree to which the Waikato River water level will change following the abstraction. This has then been compared to the degree at which, river levels change at the Waikato intake (and downstream) by the tide on a daily basis. The hydraulic assessment indicates worst case scenario incremental water level reduction, if the consented baseline of 150,000 m3/day (net) is taken into account approximately 46 mm and cumulative (including the existing Watercare take) water level reductions of 82 mm in the river reach

18 As provided by Watercare summarising discharges between 2015 and 2020.

Tonkin & Taylor Ltd 44 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd in the vicinity of the intake (T+T, 2020). Cumulative changes in mean flow velocity are no greater than 0.006 m/s (incremental change of 0.003 m/s). The magnitude of these changes would progressively decrease at higher flows and with distance downstream: for instance, in the lower wetland reaches at the delta the incremental reduction in water level will be approximately 11 mm, with a cumulative effect of 19 mm around spring high tide. The influence of tides on the lower Waikato River mean that the water regime is dynamic. As discussed in Hydrology report, the tidal range at the river mouth is approximately 1.8 m during a neap tide and 3.2 m during a spring tide. At the intake site, the average tidal range is 500 mm but up to 1.0 m during a spring tide coinciding with low flow conditions. The daily changes in water level downstream of the intake due to the tide would be a far more significant influence on habitat than the changes due to the proposed additional water take. A range of fish species and invertebrates use the low water velocity zones close to the riverbank to move upstream and downstream, away from the main current. While the lower Waikato River is considered to be of high ecological value, the magnitude of the changes to water levels along the river margins due to the proposed increase in take is considered to be negligible in comparison to daily influences from the tide and frequent increased flows due to catchment freshes and floods. The potential for indirect effects on freshwater biota through changes to water quality such as increases in temperature or dissolved oxygen have also been assessed as being negligible in section 8.3.1. Overall, the potential magnitude of ecological effect from the change in water depth from the 3 abstraction of an additional 150,000 m /day (net) from the Waikato River under q5 conditions (worst case) is considered Low resulting in an overall Low9 level of effect.

8.3.4.2 Effects on īnanga spawning habitat As noted in section 5.2.2.2 īnanga spawning in the Waikato River is known to occur up to the elbow (approximately 10 km downstream of the intake), however, is likely to extend further upstream. Modelling of hydraulic effects (T+T, 2020) in the lower wetlands reach of the river has been undertaken based on conservative q5 conditions at spring high tide to best align with the tidal conditions of when īnanga spawning typically occurs. It is unlikely that cumulative reductions in water level of up to 82 mm in the intake reach (incremental change of 46 mm19) and up to 19 mm (incremental change of 11 mm19) in the lower wetlands at spring high tide would have an adverse effect on īnanga spawning given the highly variable environment in which īnanga spawn. Spawning vegetation in the tidally influenced zone and īnanga spawning behaviour will likely adjust to small changes to the water regime. Further, changes in mean flow velocity in the lower wetlands reach at high tide would not be measurable equating to 0.001 m/s (an incremental change of 0.000 m/s). According to the Waikato River Independent Scoping Study (NIWA, 2012) the main limiting factor to īnanga in the Waikato River is the loss of adult habitat. In 1989, it was noted that there were large amounts of intact spawning habitat in the Waikato River that were sparsely used (Mitchell, 1990). Habitat for inanga spawning within the Waikato River is appears to be largely limited by changes to channel morphology and bankside vegetation as a result of human activities such as flood protection works and stock access (NIWA, 2012) rather than changes in flow. Spawning sites are known to shift around in response to changes in tidal movement, river flow and disturbance. Given the average daily tidal range of 0.5 m at the intake and 1.8 m downstream in the wetland, īnanga will be capable of selecting new spawning sites even if the small change in water level does result in shifts in spawning habitat. If vegetation used for spawning responds to

19 Change in water level specifically associated with the 150,000 m3/day (net) take

Tonkin & Taylor Ltd 45 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd reductions in water level, then it is likely that it will shift laterally down the channel banks and longitudinally upstream and may not result in any net loss of spawning habitat area. Hydrodynamic modelling in the lower Waikato River indicates that īnanga spawning may be more constrained by high river flows than by low river flows due to the presence of stopbanks close to the main river constricting potential spawning habitat during higher flows (Jones & Hamilton, 2014). The lower Waikato River is considered to be of high value and the wetlands further downstream considered very high value. Based on our assessment above, the magnitude of the effects on the īnanga spawning habitat in the lower Waikato River from the proposed abstraction at the Waikato intake are considered to be negligible to low in comparison to influences from the tide and climatic conditions. Overall, the magnitude of effect on īnanga spawning habitat resulting from the abstraction of an additional 150,000 m3/day (net) is considered Low in the Lower Waikato downstream on the intake where the incremental change in water levels under q5 conditions would be up to 46 mm resulting in an overall Very Low9 level of effect. Further downstream in the lower wetlands and delta where the incremental change in water levels under q5 conditions would be up to 11 mm the magnitude of effects on īnanga spawning habitat is considered Negligible resulting in an overall Low9 level of effect.

8.3.4.3 Effects on upstream and downstream migration Fish migration occurs in both an upstream direction, such as whitebait moving up into the catchment, and downstream direction such as fish eggs, larvae and migrating fish moving seaward. The installation of an intake structure within these migration corridors could potentially have a negative effect on migration, potentially resulting in a localised barrier to fish passage. Fish and some invertebrates (such as shrimp) use the low water velocity zones close to the river margins to ease upstream progress. Elvers (juvenile eels) and torrent fish migrate mainly along the river bed. Zones of high water velocity which could be generated by the intake, particularly along the riverbanks, could delay and even prevent migration of some fish and shrimp species. Downstream (seaward) migration of fish eggs and larvae generally occurs in autumn and early winter. Previous studies on the lower Waikato River (e.g. Meredith et al., 1989) have found that the greatest density of fish larvae (and eggs) occurs in the middle of the river channel, which is consistent with larvae seeking regions of higher flow velocity to enhance seaward transport. The location of the proposed intake screens being no less than 25 m off the true right bank20, but not in the centre of the river channel) not only reduces the risk of interference with upstream migration of juvenile fish along the river margins, but also reduces the risk of interfering with the downstream migration of larvae and eggs in the mid channel. The proposed abstraction will decrease the volume of water flowing downstream of the water take. The predicted cumulative reduction in flow is not considered likely to have any effect on fish due to the dynamic tidal nature of the river at the point of abstraction and the fact that the take is located 36 km upstream from the sea. Reductions in mean flow velocity in the intake river reach associated with the abstraction (estimated to be a maximum of 0.006 m/s when considered cumulatively) are unlikely to have any effect on upstream and downstream migration, even for passively migrating larvae (e.g. Galaxias spp. and Gobiomorphus spp.). Passive downstream fish passage mostly occurs during the winter months when Waikato River flows are usually much higher than q5 and reductions in flow velocities will be smaller. Overall, the potential magnitude of effect with mitigation (including locating the screens away from key migration zones) on upstream and downstream fish migration is considered to be Negligible

20 Dependent on river water levels.

Tonkin & Taylor Ltd 46 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd resulting in an overall Very Low9 level of effect. The effects of impingement of eggs, larvae, juvenile or adult fish on the intake screens, or entrainment into the water supply system, are discussed below.

8.3.4.4 Fish, fish eggs and larvae impingement Fish and larvae impingement can occur when approach velocities are high enough to pin larger fish onto the screens and prevent them from moving away. Whether fish get impinged on a screen is dependent on a number of factors such as: · If screen slot widths are too wide, allowing fish to pass through the screen; · If the through-slot “approach” velocity is too high, allowing fish to be pulled towards the screen; and · If the sweep velocity is too low, fish are not assisted to move away from the screen. The current Waikato intake and proposed intake screens have 1.5 mm slot widths, consistent with the WRP and are designed to have “approach” velocities of less than 0.15 metres per second. WRP specifies approach velocity must be less than 0.3 m/s. To provide maximum protection it is desirable for water velocities parallel with the screen (i.e. the sweep velocity) to be at least twice the approach velocity. Previous surveys of the current intake screen have shown sweep velocities to be at least twice that of the approach velocities. Under such conditions, fish (and debris) is more likely to move along the screen than to become impinged upon it. Monitoring undertaken since the establishment of the current Waikato intake (outlined in section 6) has not recorded any aquatic organisms impingement on the surface of the screens. The existing intake is located approximately 25 m from the river bank and the proposed intake structure will be located at a similar distance from the bank directly downstream of the existing intake. This location further minimises the risk of impingement, with the screens positioned as far as practicable away from the banks and river bed where most upstream migration occurs and in deep fast water where sweep velocities are highest. In summary key mitigation proposed include: · locate the screens away from the bank but not in the centre of the river, · 1.5 mm slot widths on the wedge wire screen; · “approach” velocities of less than 0.15 m/s; and · sweep velocity to be at least twice the approach velocity. Overall, the potential magnitude of effect with mitigation from the operation of the intake on fish eggs and larvae impingement are Negligible resulting in an overall Very Low9 level of effect.

8.3.4.5 Fish eggs and larvae entrainment Fish egg and larvae entrainment occurs when fish eggs and larvae pass through the screens of the intake. The risk of fish eggs and larvae entrainment is reduced by the use a fine mesh size and to ensure the placement of the intake structure is away from the location at which fish egg and larvae movement will be in its highest densities. The proposed mesh size of 1.5 mm is consistent with the current intake design and is intended to reduce the rate of passage through the screens. Further, the entrainment of fish eggs and larvae smaller than the nominal 1.5 mm slot size has been minimised by placing the intake away from the centre of the river channel, where their densities are expected to be the highest. Since 2003 routine monitoring has been carried out of the current screens to assess their effectiveness of preventing fish egg and larvae entrainment. As outlined in section6, the entrainment surveys carried out at the current intake structure between 2004 and 2020 have shown

Tonkin & Taylor Ltd 47 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd that on average entrainment of fish eggs and larvae occurs at levels no greater than would be expected based on densities in the main river channel. While the lower Waikato River is considered to be of high value, the magnitude of the effects of the intake screens with regards to the entrainment of fish eggs and larvae are considered negligible due to the results of the entrainment monitoring programme indicating that entrainment of fish eggs and larvae occurs at levels no greater than would be expected based on densities in the main river channel. In summary key mitigation proposed include: · locate the screens away from the bank but not in the centre of the river; · 1.5 mm slot widths on the wedge wire screen; and · “approach” velocities of less than 0.15 m/s. Overall, the potential magnitude of effect with mitigation from the operation of the Waikato Intake on fish eggs and larvae entrainment are Low resulting in an overall Low9 level of effect.

8.3.4.6 Effects on riparian and wetland values The lower Waikato River supports regionally and nationally significant wetlands along the main channel and islands of the delta. Wetlands are known to be sensitive to changes in hydrology, to the extent that even relatively small changes can influence the structure and function of wetlands. Modelling presented as part of the Hydrological Assessment (T+T, 2020) indicates that under the worst case scenario21 there would be a cumulative water level reduction of 19 mm (incremental change of 11 mm22) at spring high tide and 25 mm (incremental change of 14 mm) at spring low tide in the river reaches through the wetlands (approximately 13 km from the river mouth). At Hood’s Landing within the delta water level vary with the 12 hour daily tidal cycle, up to 1.0 m and 1.8 m at neap and spring tides respectively. These regular fluctuations in water level are significantly greater than, and are expected to mitigate, any impacts caused by the changes in water level associated with the Watercare take. The hydrodynamic processes in the estuarine area (i.e. from the river mouth for approximately 16 km through the wetland reach) are generally dominated by river flows (Hume et al., 2007; Jones and Hamilton, 2014). Therefore, while the effects on water level are small (relative to tidal fluctuations), the reduction in flow rate as a result of this proposed take could have an effect on the wetlands. However, considering the average flow reduction at the intake is less than 1% of both the median and q5 rates, such effects are also considered to be low in magnitude. Overall, the magnitude of effect on wetlands resulting from the abstraction of additionally up to 3 150,000 m /day (net) from the Waikato River under q5 conditions is considered Negligible. Because wetland values were assessed as Very High the overall level of effect was determined to be Low9.

8.3.4.7 Intake screen cleaning For the purpose of this application the use of sparging and a brush screen have been considered with an effects assessment on river freshwater biota provided for each. The existing intake screens have been designed to permit back flushing by air “sparging”. In addition to this regular sparging, the screens are cleaned periodically by high pressure water blasting. The sparging and cleaning processes remove biofilm and deposited sediment from the outside of the screens, in quantities that are unlikely to affect downstream water quality (as discussed in section

21 Combined abstraction of 300,000 m3/day at spring high tide. 22 Change in water level specifically associated with the 150,000 m3/day (net) take

Tonkin & Taylor Ltd 48 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd 8.3.2). During the sparging process air is flushed through the screens resulting in a large burst of air through the screen and up through the water column. The location of the screens in the deep, faster-flowing water means that there are unlikely to be any fish present to be disturbed by this activity. Any disturbance would also be temporary only lasting a matter of minutes. The use of the brush screen has the potential to affect any fish located on or close to the screens as the screens rotate. As noted above, the location of the screens in the deep, faster-flowing water means that fish are unlikely to be present in this area. As noted in section 8.3.4.4 previous surveys of the current intake screen have shown sweep velocities to be at least twice that of the approach velocities. Under such conditions, any fish present and debris are more likely to move along the screen than to become impinged upon it. It is therefore likely that fish would simply move out of the way of the brush as the screen rotates. Due to the rate at which the screens rotate it is anticipated that any fish would freely move away from the screen surface. The key mitigation proposed for both proposed screen cleaning mechanisms focuses on positioning and operation of the intake to avoid the presence of fish around the intake itself. In summary this includes: · locating the screens away from the bank but not in the centre of the river; · 1.5 mm slot widths on the wedge wire screen to avoid fish impingement and entertainment; and · “approach” velocities of less than 0.15 m/s to also fish impingement and entertainment. Overall, the potential magnitude of effect from the operation from either intake screen cleaning system are Negligible resulting in an overall Very Low9 level of effect.

8.4 Summary of effects Table 8-3 provides a summary of the effects addressed in this river ecological assessment. Overall, the effects on river ecological values associated with the construction and operation of the Waikato Intake structure and abstraction of the water from the Waikato River and operational discharges are between Low and Very Low. Therefore, the overall level of effect on river ecological values is Low. There can be a high level of confidence in our predictions of effects due to the existing monitoring that has occurred under a similar intake structure and WTP discharge regime operating immediately adjacent to the location proposed under this application. Given the proposed works and design, and overall effect on ecological values as determined through this assessment, no further mitigation measures beyond those identified above such as specific parameters around the screens, and included as part of the proposal, are considered to be required.

Tonkin & Taylor Ltd 49 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Table 8-3: Magnitude and level of effect for activities before and after mitigation. Magnitude and overall level of effects determined using the tables in Appendix B.

Phase Effect/activity Effect without mitigation Magnitude of Key mitigation measures Magnitude Overall effects with no of effects level of mitigation with effect with mitigation mitigation Construction Effects on river water quality Elevated suspended Low Spoil disposed of offsite, operate Negligible Very Low sediment and reduced within a coffer dam. clarity immediately downstream of the pile or coffer dam locations due to disturbance of the river bed Effects on the river bed Permanent river bed Low Minimise temporary and permanent Low Low disturbance would be structures on the river bed. No approximately 200 m2. specific mitigation provided / Temporary disturbance required. would be approximately 540 m2. Effects on river freshwater Reduced water clarity for Low No specific mitigation provided / Low Low biota visual feeders (trout), required. sedimentation to the bed of the river and associated habitat quality effects, direct disturbance to benthic habitats, and disruption to fish passage and upstream migrating fish species. Operational Effects on river temperature Changes will not be within Negligible No specific mitigation provided / Negligible Very Low effects and DO due to reduced flow the resolution of most data required. in the Waikato River recorders, at less than 0.02 °C and less than 0.01 mg/L

50 Tonkin & Taylor Ltd Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Phase Effect/activity Effect without mitigation Magnitude of Key mitigation measures Magnitude Overall effects with no of effects level of mitigation with effect with mitigation mitigation Effects on river water quality Mobilisation of organic Negligible No specific mitigation provided / Negligible Very Low through routine cleaning of (algal) material into the required. the intake screens water column of the lower Waikato River. Effect of the Soluble Toxicity to river biota. Negligible No specific mitigation provided / Negligible Very Low discharge on aluminium required. water quality Free available Toxicity to river biota. Moderate De-chlorination; Negligible Very Low and the chlorine ecology of the lower Glycerine Toxicity to river biota. Moderate Removal of high dosage glycerine off Negligible Very Low Waikato site; River Fluoride Toxicity to river biota. Negligible No specific mitigation provided / Negligible Very Low required. Total Toxicity to river biota. Negligible No specific mitigation provided / Negligible Very Low suspended required. solids Effects on River habitat Maximum incremental Low No specific mitigation provided / Low Low river water level change up to 46 required. freshwater mm (cumulative 82 mm) biota through and flow velocity reduction the operation up to 0.003 m/s (cumulative of the intake 0.006 m/s) at the intake. screens Īnanga Maximum incremental Negligible No specific mitigation provided / Negligible Low (based spawning water level change in the required. on lower habitat lower wetlands of up to 11 wetland mm (cumulative 19 mm) at ecological spring high tide. value of very high)

Tonkin & Taylor Ltd 51 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Phase Effect/activity Effect without mitigation Magnitude of Key mitigation measures Magnitude Overall effects with no of effects level of mitigation with effect with mitigation mitigation Upstream Have a negative effect on Low Locate the screens away from the Negligible Very Low and migration corridors, bank but not in the centre of the downstream potentially resulting in a river. migration localised barrier to fish passage. Fish, fish egg Fish impinged onto the Moderate Locate the screens away from the Negligible Very Low and larvae screen. bank but not in the centre of the impingement river, 1.5 mm slot widths on the wedge wire screen and “approach” velocities of less than 0.15 metres per second. Fish egg and Fish eggs and larvae Moderate Locate the screens away from the Low Low larvae entrained through the bank but not in the centre of the entrainment screen. river, 1.5 mm slot widths on the wedge wire screen and “approach” velocities of less than 0.15 metres per second. Effects on Due to the width of the Negligible No specific mitigation provided / Negligible Low (based riparian and delta and influence of tidal required. on lower wetland fluctuations water level, wetland values change in the wetlands are ecological predicted to be small value of (incremental water level very high) change up to 14 mm, cumulative 25 mm based on spring low tide conditions). Intake screen Fish being damaged by the Low Locate the screens away from the Negligible Very Low cleaning rotating brush screen. Fish bank but not in the centre of the disturbance through river, 1.5 mm slot widths on the sparging. wedge wire screen and “approach” 52 Tonkin & Taylor Ltd Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Phase Effect/activity Effect without mitigation Magnitude of Key mitigation measures Magnitude Overall effects with no of effects level of mitigation with effect with mitigation mitigation velocities of less than 0.15 metres per second to avoid fish entrainment.

Tonkin & Taylor Ltd 53 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd 9 Reference list

ANZG (2018). Australia New Zealand Freshwater and Marine Water Quality Guidelines. https://www.waterquality.gov.au/anz-guidelines/guideline-values/default/water-quality- toxicants/search Auckland Regional Council, (2004). Overview of the Effects of Residual Flocculants on Aquatic Receiving Environments. Auckland Regional Technical Publication Number 226. Boubee, J.A.T., 1994, Waikato River Pipeline – Review of Fish Protection Technology for Water Intakes. Prepared for Watercare Services Limited. Camargo, JA. 1996. Comparing levels of pollutants in regulated rivers with safe concentrations of pollutants for fishes: a case study. Chemosphere 33, 81-90. Clarkson. B, Merrett. M, Downs. T. (2002). Botany of the Waikato, Waikato Botanical Society. Collier, K. C. and Lill, A. (2008). Spatial patterns in the composition of shallow-water macroinvertebrates of a large New Zealand river. New Zealand Journal of Marine and Freshwater Research, 42, 129–141. Collier, K. C., Hamer, M. P., and Davenport, M. W. (2011). Artificial substrate monitoring of macroinvertebrates in the Waikato River: 25 years on (Technical Report 2011/25). Waikato Regional Council Technical Report 2011/25. Collier, K. J. and I. D. Hogg. (2010). Macroinvertebrates. In Collier, K. J., Hamilton, D. P., Vant, W. N. & Howard-Williams C. (eds), The Waters of the Waikato: Ecology of New Zealand's longest river. Waikato Regional Council, Hamilton, 175-192. Collier, K. J., and Hamer, M. P. (2014). Aquatic invertebrate communities and functional indicators along the lower Waikato River (Waikato Regional Council Technical Report 2014/02). Waikato Regional Council. https://www.waikatoregion.govt.nz/assets/WRC/WRC-2019/TR201402.pdf Dunn, N. R., Allibone, R. M., Closs, G. P., Crow, S. K., David, B. O., Goodman, J. M., Griffiths, M., Jack, D. C., Ling, N., Waters, J. M., and Rolfe, J. R. (2018). Conservation status of New Zealand freshwater fishes, 2017 (New Zealand Threat Classification Series 24). Department of Conservation, Wellington. Envirostart Consulting Ltd. 2018. Waikato and Waipā River restoration strategy - Volume 1 & Volume 2 Waikato Regional Council TR 2018/08 Gensemer, R.W and Playle, R.C. (1999). The Bioavailability and Toxicity of Aluminium in Aquatic Environments. Critical Reviews in Environmental Science and Technology - 29. 315-450. 10.1080/10643389991259245. GHD. (2020) Waikato River Take – Waikato Intake Feasibility Report. Prepared for Watercare Services Limited. Hamer, M. (2007). The Freshwater Fish Spawning Calendar Report. Environment Waikato Technical Report 2007/11. Hickford, M., Cagnon, M., and Schiel, D. R. (2010). Predation, vegetation and habitat-specific survival of terrestrial eggs of a diadromous fish, Galaxias maculatus. Journal of Experimental Marine Biology and Ecology, 385, 66–72. Hicks, A., Barbee, N.C., Swearer, S.E., Downes, B.J. (2010). Estuarine geomorphology and low salinity requirement for fertilisation influence spawning site location in the diadromous fish, Galaxias maculatus. Marine and Freshwater Research 61, 1252 – 1258.

Tonkin & Taylor Ltd 54 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Hicks, M. and Hill, R. (2010). Sediment Regime – sources, transport and changes in the river bed. In K. J. Collier, D. P. Hamilton, W. N. B. Vant, and C. Howard-Williams (Eds.) The Waters of the Waikato: Ecology of New Zealand's longest river (pp. 71-92). Hamilton, New Zealand: Environment Waikato and the Centre for Biodiversity and Ecology Research (The University of Waikato). Hudson, N., Nagels, J., McGrath, W., van Assema, G., Heubeck, S., Bellingham, M. 2016. Summary of water quality monitoring undertaken in Parker Lane Stream and the lower Waikato River. Prepared for Watercare Services Limited. Jones, HFE., and Hamilton, DP. (2014). Assessment of the Waikato River estuary and delta for whitebait habitat management: field surveys, GIS modelling and hydrodynamic modelling. Report prepared for Waikato Regional Council. MacMurray, H.L. and Henderson, V.J. (2019). Morphological modelling of the Waikato river between Hamilton and Port Waikato to assess the long term effects of sand extraction. The 11th Symposium on River, Coastal and Estuarine Morphodynamics – RCEM 2019, International Association for Hydro- Environment Engineering and Research (IAHR) and the Engineering New Zealand/Water New Zealand Rivers Group in association with the University of Auckland. McDowall, R.M. 1990: New Zealand Freshwater Fishes: A Natural History and Guide. Heinemann Reed, Auckland. McDowall, R. M. (2000). The Reed Field Guide to New Zealand Freshwater Fishes. Reed Books. Meredith, A.S, Empson, P.W., Boubee, J.A.T and Mitchell, C.P. (1989). Ichthyoplankton studies on the lower Waikato River. II. Larval distributions at Huntly. Freshwater Fisheries Centre, MAFish. Report to Electricorp. New Zealand Freshwater Fisheries Report No. 109. Mitchell, C. P. (1990). Whitebait Spawning Ground on The Lower Waikato River (New Zealand Freshwater Fisheries Miscellaneous Report No. 42). Report prepared for the Department of Conservation by MAF Fisheries. Mitchell, C.P., (1994). Whitebait Spawning Ground Management (Science and Research Series No. 69). Report prepared for the Department of Conservation & Western Bay of Plenty Council by Charles Mitchell & Associates. New Zealand Topography Map. Accessed March 2020. www.topomap.co.nz NIWA. (2012). Waikato River Independent Scoping Study. Quiroz-Vázquez, P., Sigee, D.C., White, K.; (2010). Bioavailability and toxicity of aluminium in a model planktonic food chain ( Chlamydomonas– Daphnia) at neutral pH. Limnologica - Ecology and Management of Inland Waters 40(3):269-277.Roper-Lindsay, J., Fuller S.A., Hooson, S., Sanders, M.D., Ussher, G.T. (2018). Ecological impact assessment. EIANZ guidelines for use in New Zealand: terrestrial and freshwater ecosystems. 2nd edition. Taylor, M.J. (2002). The national īnanga spawning database: trends and implications for spawning site management. Science for Conservation 188. Department of Conservation Wellington. Tonkin + Taylor Ltd. (2020). Waikato River Water Take and Discharge Proposal – Board of Inquiry: River Hydrology Assessment. Prepared for Watercare Services Limited. 1014753.100 Tonkin + Taylor Ltd. (2016). Hydrology and Ecology Assessment of water abstraction at the Waikato Water Treatment Plant - Proposed Water Harvesting Application. Prepared for Watercare Services Limited. 29133.600 Tonkin + Taylor Ltd. (2013). Hydrology and Ecology Assessment associated with the extension of the Waikato Intake. Prepared for Watercare Services Limited.

Tonkin & Taylor Ltd 55 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Tonkin + Taylor Ltd. (2008). Waikato Water Intake Sedimentation Assessment. Prepared for Watercare Services Limited. 20973.800. Tonkin & Taylor Ltd. (2007). Waikato Water Supply Intake: Fisheries Management Plan (v.3). Prepared for Watercare Services Ltd, Ref. 20973.310. van der Zwan, W., and Kessels, G. (2017). Significant natural areas of the Waikato District: Terrestrial and wetland ecosystems [Waikato Regional Council Technical Report 2017/36]. Prepared for Waikato Regional Council by Kessels Ecology. Waikato Regional Council (Environment Waikato). (2001a). The Freshwater Macroinvertebrate Communities of the Waikato, Waihou and Waipa Rivers. Environment Waikato Technical Report 2001/12 Waikato Regional Council (Environment Waikato). (2001b). The Diversity and Distribution of Freshwater Fish and their Habitat in the Major Rivers of the Waikato Region. Technical Report 2001/11 Waikato Regional Council website (http://www.waikatoregion.govt.nz/Environment/Natural- resources/Water/Rivers/Waikato-River/What-lives-in-the-Waikato-River/) Waikato Regional Council. (2005). Environment Waikato (now Waikato Regional Council). (2005). Estuarine vegetation survey - Port Waikato. Environment Waikato Technical Report 2005/41. Waikato Regional Council. (2007). The freshwater fish spawning and migration calendar report. Environment Waikato Technical Report 2007/11 Waikato Regional Council. (2008). Environment Waikato (now Waikato Regional Council), (2008), The health of the Waikato River and catchment, Information for the Guardians Establishment Committee. Waikato Regional Council (2011). Artificial substrate monitoring of macroinvertebrates in the Waikato River: 25 years on. Waikato Regional Council Technical Report 2011/25 Waikato Regional Council. (2012). Lower Waikato River main channel sand abstraction policy report. Prepared for River and Catchment Services Group. Waikato Regional Council (2014). Aquatic invertebrate communities and functional indicators along the lower Waikato River. Waikato Regional Council Technical Report 2014/02 Waikato Regional Council. (2020a). Waikato River water quality monitoring programme data. Supplied by Waikato Regional Council. Waikato Regional Council. (2020b). Website and New Zealand Freshwater Fish Database March 2020

Tonkin & Taylor Ltd 56 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd 10 Applicability

This report has been prepared for the exclusive use of our client Watercare Services Limited, with respect to the particular brief given to us and it may not be relied upon in other contexts or for any other purpose, or by any person other than our client, without our prior written agreement. We understand and agree that our client will submit this report as part of an application for resource consent and that Waikato Regional Council as the consenting authority will use this report for the purpose of assessing that application.

Tonkin & Taylor Ltd

Report prepared by: Authorised for Tonkin & Taylor Ltd by:

...... …...... …...... Liza Kabrle Peter Roan Project Manager Project Director Specialist technical review by: • Dean Miller, Team Leader, Senior Freshwater Ecologist

LMI \\ttgroup.local\files\aklprojects\1014753\1014753.1000\issueddocuments\final\1014753.100.waikato boi_ecology final.docx

Tonkin & Taylor Ltd 57 Waikato River Water Take and Discharge Proposal – Board of Inquiry River Ecology Assessment Watercare Services Ltd Appendix A: Waikato River Take - Wetland Classification for Waikato Intake Structure (Beca, 2020) 21 Pitt Street, PO Box 6345, Auckland, 1141, New Zealand T: +64 9 300 9000 // F: +64 9 300 9300 E: [email protected] // www.beca.com

7 December 2020 Watercare Services Ltd Private Bag 92521 Wellesley Street Auckland 1141 New Zealand

Attention: Tanvir Bhamjii

Waikato River Take - Wetland Classification for Waikato Intake Structure

1 Scope and Purpose

The purpose of this assessment is to identify wetlands within 100m of the proposed Waikato River intake structure and pipework at the existing Waikato Water Treatment Plant (WTP) for Waikato A WTP. The assessment of identified wetlands being in accordance with Operative Waikato Regional Policy Statement and the National Policy Statement: Freshwater Management (NPS:FM).

The wetland identification and delineation are based on ecological investigations and assessments undertaken as part of the Waikato 50 WTP project as follows:

◼ Waikato 50 - Earthworks and Streamworks associated with the WTP Upgrades: Ecological Impact Assessment, August 2020, Beca Ltd. ◼ Review of historical aerial photography – Retrolens – historical image resource, http://retrolens.nz and licensed by LINZ CC-BY 3.0.

2 Freshwater Wetlands at Waikato Water Treatment Plant

Several overland flow paths run through the steep gullies down to a permanent, unnamed watercourse that flows through the site into the Waikato River (Fig. 1). Narrow wetlands have formed alongside and within the stream and are dominated by dense sward of Glyceria maxima, an aggressive aquatic weed.

Wetland habitat at the site is not assessed as naturally occurring, but rather the result of human modification of the site. This is evident particularly where the unnamed tributary has been subject to streams works such as channel widening, banks re-contouring and upstream culverting, most likely during the construction of the existing WTP and pump station.

An area of modified wetland occurs within 100m of the temporary works (~10m) and permanent works (~30m) area for the proposed intake structure and pipework for Waikato A WTP as shown in Fig. 2.

The area is similarly dominated by the aquatic weed, Glyceria maxima with the occasional willow and is bounded by armouring on the true right bank beneath the existing pump station and by steep headland on the true left (Fig. 3). Flows disperse through the Glyceria and ultimately discharge into the Waikato River across a basalt cascade which is recognised as Wāhi tapu.

Waikato River Water Take and Discharge Proposal – Board of Inquiry | Page 1

A review of historical photos (1926-1988) from the Retrolens website1 show the discharge point of the unnamed tributary prior to the construction of the pump station. In the 1957 and 1963 aerials, the natural tributary channel is visible as a narrow stream corridor within an unmodified topography with no obvious evidence of wetland or the widened current state (Fig.4).

Figure 1. Aquatic features within the designation2.

1 Retrolens: Historical Imagery Resource. https://retrolens.co.nz/ accessed 5th December, 2020

2 Beca, 2020. Waikato50 - Interim Water Treatment Plant Upgrades. Earthworks and streamworks for the Treated Water Rising Main – Ecological Impact Assessment.

Waikato River Water Take and Discharge Proposal – Board of Inquiry | Page 2

Figure 2. Modified Glyceria-dominated wetland (light green) within the lower reach of the unnamed tributary (proposed intake structure and pipework for Waikato A shown in purple)3.

3 GHD, 2020. Waikato WTP Intake Upgrade: Option 2b Intake.

Waikato River Water Take and Discharge Proposal – Board of Inquiry | Page 3

Figure 3. Wetland adjacent proposed intake structure (Left: looking downstream; Right: looking upstream with existing pump station to the left of the tributary).

Figure 4. Unnamed tributary in 1957 (left) and 1963 (right) visible as unmodified narrow channel discharging into the Waikato River (source: Retrolens).

Date taken: 1/04/1957 Date taken: 6/09/1963 Survey Number: SN1031 Copyright: Crown Survey Number: SN1397 Copyright: Crown Elevation: 9300 Run Number: C Elevation: 16500 Photo Number: 6 Run Number: 3253 Scale: 13500 Photo Number: 21 Scale: 23900

Waikato River Water Take and Discharge Proposal – Board of Inquiry | Page 4

3 Assessment Against Statutory Wetland Definitions

Waikato Regional Policy Statement and NPS Freshwater 2020 definitions:

The Operative Waikato Regional Policy Statement wetland definition is adapted from the Resource Management Act. “Wetland” is defined as;

“permanently or intermittently wet areas, shallow water, and land/water margins that support a natural ecosystem of plants and animals that are adapted to wet conditions, including within the coastal marine area.”

Under the NPS FM, natural wetland means a wetland (as defined in the Act) that is not:

(a) A wetland constructed by artificial means (unless constructed to offset impacts on, or restore an existing or former wetland); or

(b) A geothermal wetland; or

(c) Any area of improved pasture that, at the commencement date, is dominated by (that is more than 50% of) exotic pasture species and is subject to temporary rain derived water pooling.”

Assessment: The wetland mosaic present within the unnamed tributary and more specifically the area adjacent the proposed intake structure meets the definition of a wetland under the Waikato RPS. This is due to the presence of hydrophytic vegetation (Glyceria maxima4) i.e. plant species capable of growing in soils that are often or constantly saturated with water during the growing season5. Furthermore, Glyceria maxima is considered a facultative wetland species6 i.e. usually found in wetlands (67%-99%) and as such, in its current state, provides wetland-like habitat. The NPS FW however, narrows the definition of a natural wetland by providing exclusion criteria to account for historic modification that may have resulted in functional, but not “natural” wetlands. The subject wetland has developed by ‘artificial means’ as a result of historic cut and fill to create the building platform for the existing pump station and existing plant. The true right bank of the unnamed tributary has been widened and armoured. Changes in hydrology upstream of this reach due to widening of the stream banks for attenuation purposes has also reduced stream flows and Glyceria has established, further altering the stream, dispersing flows evenly through the widened stream profile resulting in the modified wetland now present.

As such, the subject site is not considered a natural wetland under the NPS Freshwater 2020.

4 https://www.nzpcn.org.nz/flora/species/glyceria-maxima/

5 Clarkson, BR. 2018. Wetland Delineation Protocols,. Landcare Research, Hamilton.

6 Clarkson BR, Champion PD, Johnson PN, Bodmin KA, Forester l, Gerbeaux P, Reeves PN 2013. Wetland indicator status ratings for New Zealand species. Landcare Research, Hamilton.

Waikato River Water Take and Discharge Proposal – Board of Inquiry | Page 5

Yours sincerely

Claire Webb Associate - Ecologist on behalf of Beca Limited Phone Number: +6493002496 Email: [email protected]

Copy Jon Reed, Jenny Vince

Waikato River Water Take and Discharge Proposal – Board of Inquiry | Page 6

Appendix B: EcIA Guidelines Tables Appendix B Table A.1: Ecological values assigned freshwater ecology (adapted from Roper- Lindsay et al., 2018)23

Value Explanation Characteristics Very High A reference quality Benthic invertebrate community typically has high diversity, watercourse in condition species richness and abundance. close to its pre-human Benthic invertebrate community contains many taxa that are condition with the expected sensitive to organic enrichment and settled sediments. assemblages of flora and Benthic community typically with no single dominant species fauna and no contributions of or group of species. contaminants from human MCI scores typically 120 or greater. induced activities including agriculture. Negligible EPT richness and proportion of overall benthic invertebrate degradation e.g., stream community typically high. within a native forest SEV scores high, typically >0.8. catchment. Fish communities typically diverse and abundant. Riparian vegetation typically with a well-established closed canopy. Stream channel and morphology natural. Stream banks natural typically with limited erosion. Habitat natural and unmodified. High A watercourse with high Benthic invertebrate community typically has high diversity, ecological or conservation species richness and abundance. value but which has been Benthic invertebrate community contains many taxa that are modified through loss of sensitive to organic enrichment and settled sediments. riparian vegetation, fish Benthic community typically with no single dominant species barriers, and stock access or or group of species. similar, to the extent it is no MCI scores typically 80-100 or greater. longer reference quality. Slight to moderate EPT richness and proportion of overall benthic invertebrate degradation e.g., exotic forest community typically moderate to high. or mixed forest/agriculture SEV scores moderate to high, typically 0.6-0.8. catchment. Fish communities typically diverse and abundant. Riparian vegetation typically with a well-established closed canopy. No pest or invasive fish (excluding trout and salmon) species present. Stream channel and morphology natural. Stream banks natural typically with limited erosion. Habitat largely unmodified.

23 Boffa Miskell Limited have developed these assessment criteria and applied them to a wide range of projects. Value Explanation Characteristics Moderate A watercourse which contains Benthic invertebrate community typically has low diversity, fragments of its former values species richness and abundance. but has a high proportion of Benthic invertebrate community dominated by taxa that are tolerant fauna, obvious water not sensitive to organic enrichment and settled sediments. quality issues and/or Benthic community typically with dominant species or group sedimentation issues. of species. Moderate to high degradation MCI scores typically 40-80. e.g., high-intensity agriculture catchment. EPT richness and proportion of overall benthic invertebrate community typically low. SEV scores moderate, typically 0.4-0.6. Fish communities typically moderate diversity of only 3-4 species. Pest or invasive fish species (excluding trout and salmon) may be present. Stream channel and morphology typically modified (e.g., channelised) Stream banks may be modified or managed and may be highly engineered and/or evidence of significant erosion. Riparian vegetation may have a well-established closed canopy. Habitat modified. Low A highly modified Benthic invertebrate community typically has low diversity, watercourse with poor species richness and abundance. diversity and abundance of Benthic invertebrate community dominated by taxa that are aquatic fauna and significant not sensitive to organic enrichment and settled sediments. water quality issues. Very high Benthic community typically with dominant species or group degradation e.g., modified of species. urban stream MCI scores typically 60 or lower. EPT richness and proportion of overall benthic invertebrate community typically low or zero. SEV scores moderate to high, typically less than 0.4. Fish communities typically low diversity of only 1-2 species. Pest or invasive fish (excluding trout and salmon) species present. Stream channel and morphology typically modified (e.g. channelised). Stream banks often highly modified or managed and maybe highly engineered and/or evidence of significant erosion. Riparian vegetation typically without a well-established closed canopy. Habitat highly modified.

Appendix B Table A.2: Criteria for describing magnitude of effect (Roper-Lindsay et al., 2018)

Magnitude Description Very high Total loss of, or very major alteration to, key elements/features/ of the existing baseline1 conditions, such that the post-development character, composition and/or attributes will be fundamentally changed and may be lost from the site altogether; AND/OR Loss of a very high proportion of the known population or range of the element/feature Magnitude Description High Major loss or major alteration to key elements/features of the existing baseline conditions such that the post-development character, composition and/or attributes will be fundamentally changed; AND/OR Loss of a high proportion of the known population or range of the element/feature Moderate Loss or alteration to one or more key elements/features of the existing baseline conditions, such that the post-development character, composition and/or attributes will be partially changed; AND/OR Loss of a moderate proportion of the known population or range of the element/feature Low Minor shift away from existing baseline conditions. Change arising from the loss/alteration will be discernible, but underlying character, composition and/or attributes of the existing baseline condition will be similar to pre-development circumstances or patterns; AND/OR Having a minor effect on the known population or range of the element/feature Negligible Very slight change from the existing baseline condition. Change barely distinguishable, approximating the ‘no change’ situation; AND/OR Having negligible effect on the known population or range of the element/feature 1 Baseline conditions are defined as ‘the conditions that would pertain in the absence of a proposed action’ (Roper-Lindsay et al., 2018).

Appendix B Table A.3: Timescale for duration of effects (Roper-Lindsay et al., 2018)

Timescale Description Permanent Effects continuing for an undefined time beyond the span of one human generation (taken as approximately 25 years) Long-term Where there is likely to be substantial improvement after a 25 year period (e.g. the replacement of mature trees by young trees that need > 25 years to reach maturity, or restoration of ground after removal of a development) the effect can be termed ‘long term’ Temporary1 Long term (15-25 years or longer – see above) Medium term (5-15 years) Short term (up to 5 years) Construction phase (days or months) 1 Note that in the context of some planning documents, ‘temporary’ can have a defined timeframe

Appendix B Table A.4: Criteria for describing overall levels of ecological effects (Roper-Lindsay et al., 2018)

Ecological Very high High Moderate Low Negligible value Magnitude Very high Very high Very high High Moderate Low High Very high Very high Moderate Low Very low Moderate High High Moderate Low Very low Low Moderate Low Low Very low Very low Negligible Low Very low Very low Very low Very low Positive Net gain Net gain Net gain Net gain Net gain Appendix C: Waikato Raw Water - Watercare 2016 – 2020

Component Name Unite ANZG (2018) Average Max Min 1-1-1-2-tetrachloroethan mg/L 0 0 0 1-1-1-trichloroethane mg/L 0 0 0 1-1-2-2-tetrachloroethan mg/L 0 0 0 1-1-2-trichloroethane mg/L 0 0 0 1-1-dichloroethane mg/L 0 0 0 1-1-dichloroethene mg/L 0 0 0 1-1-dichloropropene mg/L 0 0 0 1-2-3-trichlorobenzene mg/L 0 0 0 1-2-3-trichloropropane mg/L 0 0 0 1-2-4-trichlorobenzene mg/L 0 0 0 1-2-4-trimethylbenzene mg/L 0 0 0 1-2-dibromo-3-chloroprop mg/L 0 0 0 1-2-dibromoethane mg/L 0 0 0 1-2-dichlorobenzene mg/L 0 0 0 1-2-dichloroethane mg/L 0 0 0 1-2-dichloropropane mg/L 0 0 0 1-3-5-trimethylbenzene mg/L 0 0 0 1-3-dichlorobenzene mg/L 0 0 0 1-3-dichloropropane mg/L 0 0 0 1-4-dichlorobenzene mg/L 0 0 0 2-2-dichloropropane mg/L 0 0 0 2-chlorotoluene mg/L 0 0 0 4-chlorotoluene mg/L 0 0 0 Acenaphthalene µg/L 0 0 0 Acenaphthene µg/L 0 0 0 Alachlor µg/L 0 0 0 Aldrin µg/L 0 0 0 alpha-BHC µg/L 0 0 0 alpha-Chlordan µg/L 0 0 0 Aluminium mg/L 0.055 0.421287377 3.4 0 Ammonia mg/L 0.9 0.016125 0.045 0 Anthracene µg/L 0 0 0 Antimony mg/L 0.009 0 0 0 Arsenic mg/L 0.014395 0.025 0.0076 Atrazine µg/L 0 0 0 Azinphos methyl µg/L 0 0 0 Barium mg/L 0.023782609 0.032 0.018 Benz[a]anthracene µg/L 0 0 0 benzene mg/L 0 0 0 Benzo[a]pyrene µg/L 0 0 0 Benzo[b]fluoranthene µg/L 0 0 0 Benzo[g,h,i]perylene µg/L 0 0 0 Benzo[k]fluoranthene µg/L 0 0 0 Component Name Unite ANZG (2018) Average Max Min Benzylbutyl phthalate µg/L 0 0 0 Beryllium mg/L 0.00013 4.91304E-06 5.8E-05 0 beta-BHC µg/L 0 0 0 Boron mg/L 0.37 0.157434783 0.23 0.092 Bromacil µg/L 0 0 0 bromobenzene mg/L 0 0 0 bromodichloromethane mg/L 0 0 0 bromoform mg/L 0 0 0 bromomethane mg/L 0 0 0 Cadmium mg/L 0.0002 0 0 0 Calcium mg/L 7.738947397 10 6 Calcium Hardness mg/L 19.32258065 25 15 carbon tetrachloride mg/L 0 0 0 chlorobenzene mg/L 0 0 0 chloroform mg/L 0 0 0 chloromethane mg/L 0 0 0 Chlorpyriphos µg/L 0 0 0 Chromium mg/L 0.0033 0.000810435 0.0019 0 Chrysene µg/L 0 0 0 cis-1-2-dichloroethylene mg/L 0 0 0 cis-1-3-dichloropropene mg/L 0 0 0 Copper mg/L 0.0014 0.000763913 0.0018 0.00026 Cyanazine µg/L 0 0 0 delta-BHC µg/L 0 0 0 Di(2-ethylhexyl) adipate µg/L 0 0 0 Di(2-ethylhexyl) phthalate µg/L 0 0 0 Diazinon µg/L 0 0 0 Dibenz[a,h]anthracene µg/L 0 0 0 dibromochloromethane mg/L 0 0 0 dibromomethane mg/L 0 0 0 dichlorodifluoromethane mg/L 0 0 0 Dieldrin µg/L 0 0 0 Diethyl phthalate µg/L 0 0 0 Dimethyl phthalate µg/L 0 0 0 Di-n-butyl phthalate µg/L 0 0 0 E.coli cfu/100 mL 398.42 5300 16 Endosulfan I µg/L 0 0 0 Endosulfan II µg/L 0 0 0 Endosulfan sulfate µg/L 0 0 0 Endrin µg/L 0 0 0 Endrin aldehyde µg/L 0 0 0 Epichlorhydrin mg/L 0 0 0 Escherichia coli MPN/100 mL 109.5 170 49 ethylbenzene mg/L 0 0 0 ethylchloride mg/L 0 0 0 Filtration Status (blank) Fluorene µg/L 0 0 0 Fluoride mg/L 0.137962962 0.2 0.09 Component Name Unite ANZG (2018) Average Max Min Fluoroanthene µg/L 0 0 0 fluorotrichloromethane mg/L 0 0 0 Formaldehyde mg/L 0 0 0 gamma-BHC (lindane) µg/L 0 0 0 Gamma-chlordane µg/L 0 0 0 Heptachlor µg/L 0 0 0 Heptachlor epoxide µg/L 0 0 0 Hexachlorobenzene µg/L 0 0 0 hexachlorobutadiene mg/L 0 0 0 Hexazinone µg/L 0 0 0 Indeno[1,2,3-c,d]pyrene µg/L 0 0 0 Iron mg/L 0.3 0.538491072 1.8 0.032 iso-propylbenzene mg/L 0 0 0 Lead mg/L 0.0034 0.000354783 0.00087 0.00014 Lithium mg/L 0.052 0.077 0.03 m- & p-xylene mg/L 0 0 0 Magnesium mg/L 1.9 2.701098887 3.1 2.3 Magnesium Hardness mg/L 11.11720431 13 9.6 Manganese mg/L 0.038047589 0.12 0.00051 Mercury mg/L 0.0006 0 0 0 Metalaxyl µg/L 0 0 0 Methoxychlor µg/L 0 0 0 methylene chloride mg/L 0 0 0 Metolachlor µg/L 0 0 0 Metribuzin µg/L 0 0 0 Molinate µg/L 0 0 0 Molybdenum mg/L 0.034 0.000183478 0.00047 0 naphthalene µg/L 0 0 0 n-butylbenzene mg/L 0 0 0 Nickel mg/L 0.011 0.000493043 0.0016 0.0002 Nitrate mg/L 0.523633334 1.1 0.019 Nitrite mg/L 0.003579661 0.014 0 n-propylbenzene mg/L 0 0 0 Oryzalin µg/L 0 0 0 Oxadiazon µg/L 0 0 0 o-xylene mg/L 0 0 0 PCB congener #101 µg/L 0 0 0 PCB congener #138 µg/L 0 0 0 PCB congener #183 µg/L 0 0 0 PCB congener #28 µg/L 0 0 0 PCB congener #8 µg/L 0 0 0 Pendimethalin µg/L 0 0 0 Permethrin (cis + trans) µg/L 0 0 0 pH pH unit 7.489449536 10.5 6.6 Phenanthrene µg/L 0 0 0 Pirimiphos-meth µg/L 0 0 0 p-isopropyl toluene mg/L 0 0 0 Potassium mg/L 3.0779661 3.6 2.6 Component Name Unite ANZG (2018) Average Max Min pp-DDD µg/L 0 0 0 pp-DDE µg/L 0 0 0 pp-DDT µg/L 0 0 0 Procymidone µg/L 0 0 0 Propanil µg/L 0 0 0 Propazine µg/L 0 0 0 Pyrene µg/L 0 0 0 sec-butylbenzene mg/L 0 0 0 Selenium mg/L 0.011 0 0 0 Silicon mg/L 33.56521739 42 29 Silver mg/L 0.00005 0 0 0 Simazine µg/L 0 0 0 Sodium mg/L 15.7826087 20 12 styrene mg/L 0 0 0 Terbuthylazine µg/L 0 0 0 tert-butyl benzene mg/L 0 0 0 tetrachloroethylene mg/L 0 0 0 THM Ratio 0 0 0 Tin mg/L 9.13043E-06 0.00011 0 toluene mg/L 0 0 0 Total Hardness mg/L 30.4516129 37 25 trans-1-2-dichloroethene mg/L 0 0 0 trans-1-3-dichloropropen mg/L 0 0 0 trichloroethylene mg/L 0 0 0 Trifluralin µg/L 0 0 0 Uranium mg/L 4.02609E-05 8.6E-05 2E-05 vinyl chloride mg/L 0 0 0 Zinc mg/L 0.008 0.004804348 0.019 0.0016 Appendix D: Effect of the proposed discharge on Waikato River FAC concentrations at Q5 low flow (185.9 m3/s) Discharge concentrations and loads at the In river concentration scenarios Dilution with proposed discharge rate river water Upstream Guideline Parameter / scenario Assumed concentration Assumed concentration after Assumed concentration after required to Discharge concentration value Concentration Mass Load after full mixing with 5 % of full mixing with 10 % of the Q5 full mixing mixing with 20 % achieve the rate in Waikato 3 3 3 guideline River the Q5 flow (9.3 m /s) flow (18.6 m /s) of the Q5 flow (37.2 m /s) (g/m3) (m3/s) g/s g/m3 g/m3 FAC as g/m3 FAC as g/m3 FAC as g/m3 m3/s FAC median 0.03 0.72 0.02 0.000 0.003 0.002 0.0011 0.0006 6 FAC upper non-outlier range 0.08 0.72 0.06 0.000 0.003 0.006 0.0030 0.0015 17 FAC Maximum 0.25 2.45 0.61 0.000 0.019 0.052 0.0291 0.0154 29 FAC cumulative median 0.03 1.44 0.04 0.000 0.003 0.004 0.0022 0.0011 11 FAC cumulative upper non-outlier range 0.08 1.44 0.12 0.000 0.003 0.011 0.0058 0.0030 32 FAC cumulative maximum 0.25 4.90 1.23 0.000 0.019 0.086 0.0521 0.0291 58 Appendix E: Bench testing of free available chlorine (Source: Watercare 2017) Chlorine breakdown bench test

Raw water chlorine 0.06 mg/L

Time (min) Jar 1 Jar 2 Jar 3 Jar 4 Jar 5 Jar 6 Initial Concentation(mg/L) 0 0.22 0.44 0.66 0.88 1.1 1.33 1 0.15 0.13 0.14 0.14 0.07 0.11 4 0.08 0.09 0.06 0.09 0.07 0.08 8 0.07 0.08 0.09 0.06 0.06 0.07 10 0.05 0.06 0.09 0.07 0.09 0.1 Method Hypo added to jars to obtain the concentrations in 'intial concentration' Jar tester stirrers were set as 200RPM Decay was measured over time Samples taken using Hach Pocket Colorimeter II

Breakdown of FAC at various concentrations in Waikato Raw Water 1.4 1.35 1.3 1.25 1.2 1.15 1.1 1.05 1 0.95 0.9 0.85 )

L 0.8 /

g 0.75 m

( 0.7

C 0.65 A

F 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 0 2 4 6 8 10 12 Time (minutes)

Jar 1 Jar 2 Jar 3 Jar 4 Jar 5 Jar 6