10 February 2021

@ ^{simpson Grierson}

10 February 2021

Environmental Protection Authority Private Bag 63002

WELLINGTON 6140

Partner Reference Padraig McNamara - Auckland Writer's Details Direct Dial: +64-9-977 5095 E-mail: [email protected]

For: Jillian Kennemore

By email: [email protected]

Watercare's Waikato River Take Application: Response to Stantec Report

1. In its report to the Environmental Protection Authority (EPA) entitled Review of Watercare Services Limited Resource Consent Applications for New Waikato River Take dated 3 February 2021 (Report), Stantec has recommended that Watercare provide further information on six matters before its application is publicly notified. This letter addresses those six matters, under headings taken verbatim from section 3.0 of the Report.

A map that shows the spatial extent of

the Waikato River catchment that is subject to the allocable flow calculations (noting that the allocable flow applies to both surface water and groundwater)

2. Watercare understands that the EPA has been liaising directly with the Waikato Regional Council (WRC), which will be providing a map of the catchment taken from the Waikato Regional Plan.

An explanation in the AEE of how the volume of the take (150,000m

/day) has been derived

3. In response, Watercare notes:

(a) The Assessment of Environmental Effects (AEE) provided with Watercare's application summarises, at section 5, the supply/demand assessment undertaken by Watercare and set out in more detail in two reports attached to the AEE: Demand Forecast- 2020 Update (Beca Limited and Tonkin & Taylor Limited, 2020) and Outage, Headroom and Supply Demand Balance (Beca Limited and Tonkin & Taylor Limited, 2020).

(b) The AEE identifies (at section 5.1.3) that using the demand forecast model, peak day demand is forecast to be approximately 833 MLD by 2055, while dry year annual average demand is forecast to be approximately 639 MLD by 2055.

(c) The AEE identifies (at section 5.2.1) that peak day deployable output as at 2020 is 622 MLD rising to a projected 660 MLD by 2028, while annual drought deployable output is 483 MLD in 2020 rising to a projected 501 MLD by 2028, noting that these figures do not include allowances for outage and headroom.

(d) Figures 11 and 12 in the AEE (at section 5.3) show the Baseline Annual Drought Supply Demand Balance and the Baseline Peak Period Supply Demand Balance respectively. They show the supply demand balance as being in deficit (i.e. a "gap" between the water available for use or WAFU, and

AUCKLAND: Lumley Centre, 88 Shortland Street, Private Bag 92518, Auckland 1141, New Zealand. T +64 9 358 2222 WELLINGTON: HSBC Tower, 195 Lambton Quay, PO Box 2402, Wellington 6140, New Zealand. T+644 499 4599

CHRISTCHURCH: Level 1, 151 Cambridge Terrace, West End, PO Box 874, Christchurch 8140, New Zealand. T+64 3 365 9914

wv .simpsongrierson, m

both forecast dry year average day demand and forecast dry year peak day demand) starting in 2025 - 2028 and increasing out to 2055. Tables 6-2 and 6- 3 in the Outage, Headroom and Supply Demand Balance report (at section 6.3) show the annual drought supply demand balance as being in deficit by 205 MLD by 2055, and the peak supply demand balance as being in deficit by 240 MLD by 2055.

(e) Growth in the connected population is the most significant driver of increased demand. The connected population (excluding Papakura and Waikato District populations, which are also supplied indirectly by Watercare) will increase from an estimated 1.43m in 2018 to an estimated 2.1 m people by 2055.

(f) The application as lodged with WRC in 2013 was for an additional 200 MLD, in order to meet the increase in demand driven by population growth over a 35- year term (at that time, to 2048).

(g) Notwithstanding this population growth, Watercare's ongoing consultation with Waikato-Tainui and its recognition of the special status of the River for Waikato- Tainui, has resulted in it agreeing with Waikato-Tainui to reduce its reliance on the Waikato River as a water source for Auckland over time. As part of that commitment, it has agreed to reduce its take application from 200 MLD (net) to 150MLD (net).

{h) An additional 150 MLD meets a significant portion of Auckland's demand growth over the coming decades, and will provide enough additional supply and lead time to plan for and commission another new large water source by the early 2040s.

Information on the effects of the take on the relationship of tangata whenua and their culture and traditions with their ancestral lands, water, sites, wahi tapu and other taonga and the position of other iwi and hapü on the Kawenata Whakawhanaunga

4. In response, Watercare notes:

(a) The stretch of the river in which Watercare's current take occurs and the additional 150 MLD (net) take is proposed is in the rohe of Waikato-Tai nui.

(b) The cultural effects of the application are addressed at section 9.3 of the AEE.

That section acknowledges that for Waikato-Tainui, the river is an ancestor which has prestige and represents the mana and mauri of the tribe. The cultural effects of the application extend beyond the physical/environmental effects which are described elsewhere in the AEE. However, it is not for Watercare (as opposed to mana whenua themselves) to articulate the cultural effects of the application, or in particular how mana whenua consider their relationship with the Waikato River may be affected by the application.

(c) Watercare understands that the effects of the proposed take and related activities that Waikato-Tainui are concerned about are succinctly summarised in the four fundamental issues set out in Te Ture Whaimana (the Vision and Strategy), notwithstanding that those statements relate to the effects of all human activities on the Waikato River.

Those issues have been at the forefront

Those four issues are summarised in Te Ture Whaimana as follows:

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of consultation with iwi which has taken place kanohi ki te kanohi, and are integral to the Watercare proposal including the reduction in the proposed take to 150 MLD (net).

(d) Watercare considers it is for Waikato-Tainui and other mana whenua entities to provide evidence to the Board of Inquiry on what they consider the effects of Watercare's application to be, after considering the application as lodged, AEE and supporting documentation.

(e) The AEE also discusses (in the executive summary and elsewhere) key aspects of the kawenata whakawhanaunga entered into between Watercare and Te Whakakitenga o Waikato Inc. The matters covered in the kawenata whakawhanaunga address many key concerns of Te Whakakitenga o Waikato Inc and Waikato-Tainui, but again it is for these entities to speak for themselves as to the extent to which the kawenata whakawhanaunga mitigates the effects of the application. A media statement from Waikato-Tainui relating to the kawenata whakawhanaunga is attached to this letter as Appendix A.

Clarification that allocable water is both groundwater and surface water, and an assessment of the effects of the take on groundwater levels and groundwater users.

5. Attached to this letter as Appendix B and Appendix C respectively are reports from Mitchell Daysh Limited (planning) and Tonkin & Taylor Limited (hydrology) assessing the effects of the proposed take on groundwater levels and groundwater users.

Information about of the process water discharge mixing zone

6. Further detail on the information sought appears at section 2.5.1.1 of the Report:

The Ecology Assessment should characterise the mixing zone associated with the proposed discharge of 'process water' including:

• The distance to full mixing (where the discharge plume is evenly distributed across the full width of the river);

• The lateral extent of the discharge plume between the point of discharge and point of full mixing;

• The proportion of full mixing achieved at several locations between the point of discharge and point of full mixing (say 100m, 300m and 600m below outfall).

7. The mixing zone for both the existing water treatment plant discharge and the proposed discharge are addressed in the River Ecology Assessment prepared by Tonkin & Taylor Limited which is attached to the AEE: see in particular section 7.2.1 and 8.3.3 of that report. The report identifies a "highly conservative" mixing zone of 1.1 km - 2.8km downstream of the proposed discharge point, based on a 2016 NIWA study in relation to the mixing zone for the Pukekohe Wastewater Treatment Plant treated wastewater discharge, located 11 km downstream of the proposed intake and discharge point. The

1. The degradation of the Waikato River and its catchment has severely compromised Waikato River iwi in their ability to exercise mana whakahaere or conduct their tikanga and kawa;

2. Over time, human activities along the Waikato River and land uses through its catchments have degraded the Waikato River and reduced the relationships and aspirations of communities with the Waikato River;

3. The natural processes of the Waikato River have been altered over time by physical intervention, land use and subsurface hydrological changes. The cumulative effects of these uses have degraded the Waikato River; and 4. It will take commitment and time to restore and protect the health and wellbeing of the Waikato River.

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AEE and Tonkin & Taylor Limited report identify the impact on water quality, and the ecological effects, of the proposed discharge both within and outside the zone of reasonable mixing.

8. Watercare notes that WRC did not require additional information or further detail regarding the mixing zone for the existing Waikato Water Treatment Plant discharges when the applications for these consents were considered in 2020. This reflects the nature of the water treatment plant discharges (both existing and proposed), that the magnitude of the effects of the discharges on water quality has been assessed as negligible, and that the overall level of effects has been assessed as very low.

9. The criterion used by Stantec to determine whether more information is required before notification is "whether application contains sufficient information for a person interested in the application to understand if they could potentially be affected by the proposal and may need to lodge a submission". Watercare considers the analysis of the reasonable mixing zone and the effects of the proposed discharge (both within and beyond the mixing zone) provide a sufficient level of information to allow a person to understand the effect of the application and whether they need or wish to lodge a submission. On that basis Watercare has already provided sufficient information with the application as lodged.

An assessment of the cumulative effects of the current discharge rate of process water/off spec water and the proposed discharge

10. This assessment has been provided at section 8.3.3.6 of the submitted River Ecology Assessment prepared by Tonkin &Taylor Limited.

Yours faithfully

SIMPSO GRIERSON

k-

ara I Matt Conway

Page4

From: Taipu Paki <[email protected]>

Date:

18 December 2020 at 10:37:09 AM NZDT

To:

"RFisher (Rob) 1" <[email protected]>, Rukumoana Schaafhausen <[email protected]>, Margaret Devlin <[email protected]>

Cc: Jason Ake <[email protected]>

Subject: RE: MEDIA RELEASE: Waikato-Tainui and Watercare sign Kawenata for the protection of Waikato River CAUTION:External Email!

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APPENDIX A

ii'iiiü

Press Release

Waikato-Tai nui and Watercare sign kawenata for protection of Waikato River

Restoration and protection of the Waikato River is at the heart of a new agreement signed between Waikato-Tainui and Watercare.

The kawenata between the parties provides for reduction over time in Auckland's reliance on the Waikato River

its municipal water supply, which will

an ongoing kaupapa of

signatories to the agreement.

Watercare will reduce the amount of water sought under its proposed consent application from 200,000 to 150,000 cubic metres a dsy.

The key is reducing the percentage contribution that the awa makes to Auckland's water supply needs, which means finding alternative solutions over time," Te Arataura

Rukumoana Schaafhausen says.

We've always said the health and wellbeing of our wa is paramount and this kawenata reflects this kaupapa," she ^said.

"Our agreement balances the needs of our communities with the needs of our awa for future generations."

Watercare Chair Margret Devlin acknowledged the importance of reducing Auckland's reliance on water from the Waikato River over time.

Through this kawents, we are committed to working collaboratively and in good faith with Waikato- Tainui to advance the wellbeing of the river and to explore alternative solutions for Auckland's water needs."

Ms Devlin said the kawenst would see the establishment of a Trust to fund activities to support the natural environment such as stream bank stabilisation, fish hatcheries and riparian planting as well as

monitoring and research programmes.

The kawenots is sepsrate to sny agreement between Waikato-Tainui and Auckland Council.

ENDS

Taipu Paki General Manager, Rights and Interests Mobile:

Tel:

Email:

Web:

Address: PO Box 648, 4 Bryce Street, Hamilton 3204

--~□

2

MITCHELL

DAYSH

1 O February 2021

PO Box 300 673 Albany Auckland 0752 New Zealand +64 9 486 5773 Reference: MDL001425

Tanvir Bhamji

Watercare Services Limited By email

[email protected]

Dear Tanvir

Watercare Services Limited Waikato River Take Application - Stantec Questions

Stantec has reviewed the Watercare application on behalf of the Environmental Protection Authority ("EPA"). In its report to the EPA entitled "Review of Watercare Services Limited Resource Consent Applications for New Waikato River Take" dated 3 February 2021 (the "Report"), Stantec has

recommended that Watercare provide further information on six matters before its application is publicly notified.

In relation to hydrology the Report states (at 2.2 Hydrology Review):

"We understand from WRC that the take is from the Waikato River catchment not just the Waikato River. The Waikato Regional Plan requires that all takes from the Waikato River catchment, including both groundwater and surface water, are assessed against the WRC allocable flow limits. References to ground water in the AEE relate only to water source alternatives and Watercare's existing water supplies, rather than to any effects on groundwater as a result of the proposed take. It is considered that an assessment of the proposed take on groundwater and groundwater users should be included in the application documents prior to public notification."

The Report recommends (3.0 Conclusion) that Watercare provides, prior to public notification:

"Clarification that allocable water is both groundwater and surface water, and an assessment of the effects of the take on groundwater levels and groundwater users."

This letter provides a brief assessment of the planning framework relevant to the questions asked.¹

This issue was raised informally, prior to the release of the Report in an email dated 23 December 2020, 11 :46, Stantec to EPA.

Mitchell Daysh Limited Auckland

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APPENDIX B

1. Overall Framework

As set out in the refreshed Assessment of Effects accompanying the Watercare Services Limited ("WSL") application to take up to 150,000 m?/day (net) of water from the Waikato River provided to the EPA on 11 December 2020, the Water Module section (Section 3) of the Waikato Regional Plan ("WRP") gives effect to the Waikato Regional Policy Statement and no further reference is required to higher-order documents in determining the planning matters relevant to the questions asked. This assessment therefore focusses on the WRP provisions relevant to the connection between

groundwater and surface water.

The effect of the proposed WSL Waikato River take on groundwater is assessed in the Tonkin &

Taylor document "Further information for proposed additional Watercare take from Waikato River Assessment of groundwater effects" dated 5 February 2021.

2. Groundwater vs Surface Water Allocation

The WRP is largely silent on whether surface water allocation has the potential to affect the allocation of groundwater and there are no policy provisions relating to the effects of surface water takes on groundwater. Similarly, Section 8 (Information Requirements) in the WRP does not explicitly identify any information requirements relating to the assessment of the effect of a surface water take on groundwater.

The assessment of allocation limits and flows for the application used allocation information

provided by the WRC and includes existing allocations of groundwater that may affect surface water flows in the Waikato River and applications for the taking of groundwater that were lodged with the WRC before the WSL application in December 2013. The allocation levels shown in Figure 7 (Section 4.11, page 22) and Figure 25 (Section 9.7, page 104) of the refreshed AEE include water allocated for groundwater takes that may affect surface water flows in the Waikato River.

We note that the overall objective (3.1.2) for Section 3 of the WRP recognises that groundwater should be managed to ensure that sustainable yield and that shallow groundwater takes do not affect surface water values:

3. 1.2 Objective

The management of water bodies in a way which ensures:

m) ground water quality is maintained or enhanced and ground water takes managed to ensure sustainable yield

n) shallow ground water takes do not adversely affect values for which any potentially affected surface water body is managed

The focus of the WRP is on managing groundwater to protect surface water rather than managing surface water to protect groundwater.

Mitchell Daysh Limited Auckland

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3. Groundwater - Sustainable Yield

In establishing sustainable yields for groundwater aquifers, Policy 4 requires consideration of effects on surface water and giving effect to the overarching purpose of Te Ture Whaimana:

Policy 4: Establish Sustainable Yields from Groundwater

Establish, set and review sustainable yields from groundwater resources which ore to be used when assessing authorised water tokes and resource consent applications from aquifers while having particular regard to the following matters:

o) Giving effect to the overarching purpose of the Vision and Strategy to restore and protect the health and wellbeing of the Waikato River for present and future generations.

b) The recognition of the relationship between tongoto whenuo with groundwater resources and providing for tongoto whenuo input in determining their values and interests, and reviewing the sustainable yields for those groundwater resources.

c) The protection of groundwater resource from soit intrusion.

d) The need to ensure that any groundwater discharges into surface waters ore not reduced such that there is o resultant significant adverse effect on in-stream uses and values (including wetlands and korst systems) and on other allocated use.

e) The need to ensure groundwater depletion or dewotering of aquifers does not result in significant adverse effects on resource availability.

Again, the focus is on the effect of groundwater allocation on surface water flows and surface values rather than the effect of surface water takes on groundwater. However, it is clear from this that aquifers connected to the Waikato River form part of the allocation regime for the river. This is reflected in the assessment undertaken for the WSL application, which has included any groundwater allocation that may affect surface water flows as reflected in data provided by the WRC. We note that the matters identified under Policy 4c, d and e (in terms of surface water effects) have been assessed in the Tonkin & Taylor assessment dated 5 February 2021.

If consent is granted in respect of the WSL application, any remaining allocation within the limits provided for under the Waikato Regional Plan would be available for surface water take applications or the taking of groundwater that may affect surface water flows.

There are no policy provisions relating to the assessment of surface water effects on sustainable yields from groundwater or in relation to hydraulic connections between surface water and groundwater. However, we note that Policy 1 O (i) (How Groundwater Takes will be Classified) addresses hydraulic connections between ground and surface water and the effect that a groundwater take could have on surface water. Policy 1 O (i) states that:

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i) Notwithstanding Policies a) to h), assessing the nature of hydraulic connection (if any) between groundwater takes and surface water bodies and, if there is such a connection as defined by Policy 12 w), having regard to relevant parts of Policy 11 and Policy 12 when making decisions on groundwater takes.

There is no equivalent policy relating to decisions on surface water takes where hydraulic connections are identified between surface and ground waters.

Policy 12 (w) (Consent Application Assessment Criteria - Groundwater) reinforces the WRP approach that when assessing resource consent applications for groundwater takes and/or any associated water use, particular regard will be given to the effect of a take on surface water:

w) The nature of hydraulic connection (if any) between the groundwater resource from which water is proposed to be taken and surface water bodies will generally be assessed on a case by case basis by evaluating:

i) groundwater depletion of surface water bodies (i.e., the replacement of abstracted groundwater by flows from surface water bodies); and ii) where no Table 3-6 Sustainable Yield has been identified for the

groundwater resource, groundwater interception (i.e., the reduction of groundwater flows to surface water bodies)

No equivalent "hydraulic connection" assessment is referred to in Policy 11 (Consent Application Assessment Criteria - Surface Water) with respect to the assessment of surface water take applications.

Finally, Implementation Method 3.3.4. 7 provides for management of the depletion of surface water flows by groundwater takes as follows:

3.3.4. 7 Groundwater Depletion of Surface Water

Waikato Regional Council will manage the surface water depletion effects identified by Policy 1 O i) and Policy 12 w) using either one or both of the following methods.

a) A groundwater take will have surface water restrictions imposed where there is a hydraulic connection between the two systems, and a restriction of the

groundwater take will result in an increase in surface water flows during times of restrictions.

b) Where a groundwater take is assessed under Policy 1 O i) as impacting on surface water resources and this cannot be solely managed with restrictions on the groundwater take, the reduction in surface water flow occasioned by the groundwater take will be quantified and included in the surface water allocation regime used for assessing the cumulative allocation for the surface water takes in Chapter 3.3. The remainder of the groundwater take (the actual rate of take

4

less the amount quantified as being a reduction in surface water flow) will be allocated against the sustainable yield in Table 3-6.

There is no equivalent implementation method providing for management of depletion of groundwater yields by surface takes.

The Tonkin & Taylor assessment dated 5 February 2021 concludes that the magnitudes and levels of effects based on the changes to river hydrology measured against the proposed 150,000 m?/day (net) abstraction, including effects on other groundwater users, saline intrusion to aquifers and water budgets will be negligible. There are no WRP groundwater policy implications for the proposed WSL taking of water from the Waikato River.

4. National Policy Statement for Freshwater Management 2020

Section 1.5 of the National Policy Statement for Freshwater Management 2020 ("NPSFWM ") states that the NPSFWM applies to groundwater. The proposed WSL Waikato River take will not affect the health and well-being of groundwater or any freshwater ecosystems dependant on groundwater, nor will it affect the health needs of people reliant on groundwater (including drinking water). The proposal will not affect the ability of people and communities to provide for their social, economic, and cultural well-being, now and in the future through the use of groundwater (other than by using a portion of the allocation that might otherwise be available for such uses if consent applications are made for this purpose). Similarly, the effect on groundwater arising from the proposed WSL Waikato River take will not result (directly or indirectly) in any loss of extent or values of any wetland.

We consider that the proposed WSL Waikato River take is consistent with the NPSFWM objectives and policies that relate to groundwater.

S. Water Allocation

Policy 3 (Determining the combined level of surface water allocation within a catchment) in the WRP states that in determining the combined level of surface water allocation in catchments and the activity classification of a particular surface water take, the Waikato Regional Council shall:

a) Assess all the takes on a net take basis at the point of take and at each affected downstream reach;

b) Assess all the takes for the months of the year for which the particular take will be authorised to abstract water;

c) Classify the particular surface water take on the basis of the relevant reach in the catchment (part a)) and the time of year (part b)) that gives the most onerous activity classification.

Based on this policy, and Policies 1 (Establish Allocable and Minimum Flows for Surface Water) and 2 (Determining the level of minimum flows, primary, secondary and water harvesting allocable flows) in the WRP, the Waikato River water allocation regime takes a "whole-of-river" approach. This means that an application seeking an allocation of water from the Waikato River can affect the available

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allocation in other parts of the river catchments to ensure that river flow requirements are met throughout the river system.

The allocation sought by WSL in its application to take water from the Waikato River is assessed in relation to the river flow available for allocation at the Coastal Marine Area boundary (some 27 kilometres downstream of the existing WSL intake). The assessment of available allocation at this point includes upstream allocations as well as Waikato River flows.

In practical terms, the catchment to which the WSL application to take water from the Waikato River, allocations to existing consent holders and potential allocations in respect of applications that were lodged prior to the WSL application in 2013 relates is the Waikato River catchment (including groundwater with a surface water connection).

6. Summary

In summary:

a) The water allocation assessment for the proposed WSL Waikato River water take application has included allocations of water to groundwater users where there is a connection between the groundwater aquifer where water is taken from and the Waikato River (or its tributaries);

b) There are no explicit policy provisions in the WRP relating to the effect of surface water takes on groundwater connected to surface water resources in the Waikato River catchment and in that regard, the proposed WSL Waikato River water take is consistent with WRP requirements;

c) The effect of the proposed WSL Waikato River take on groundwater is consistent with the NPSFWM objectives and policies; and

d) In practical terms, the catchment to which the WSL Waikato River take application, allocations to existing consent holders and potential allocations in respect of applications that were lodged prior to the WSL application in 2013 relates is the Waikato River catchment (including groundwater with a surface water connection).

Yours sincerely,

Richard Matthews Mitchell Daysh Ltd

[email protected]

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7Fr rnkin +rayor

Job No: 1014753.1010 5 February 2021 Watercare Services Ltd

By email

Tanvir. [email protected]

Attention: Mr T Bhamji

Dear Tanvir

Further information for proposed additional Watercare take from Waikato River Assessment of groundwater effects

In accordance with our Letter of Engagement dated 22 January 2021, we are pleased to provide this assessment of the effect on groundwater in the Waikato catchment of the Watercare Services Ltd (Watercare) proposed additional 150,000 m?/day (net) take from the Waikato River.

1 Introduction

In 2013 Watercare lodged an application with Waikato Regional Council (WRC) to take

200,000 m?/day net of water from the Waikato River near Tua kau. In August 2020, the Minister for the Environment appointed a Board of Inquiry (BOI) to hear this application, which had been in a queue of applications since its lodgement.

Tonkin and Taylor Ltd (T + T) provided ecological and hydrological assessments on the effects of the then proposed take as part of the Assessment of Effects on the Environment (AEE) for the original application, and for the revised application to the BOI 150,000 m?/day (net). As part of this work, T+T assessed the potential hydrological impacts relating to the proposed Waikato River water take'.

This letter report provides technical responses to a recommendation from Stantec to the Environmental Protection Agency (EPA) for further information relating to groundwater matters.

2 Background

2.1 Request from Stantec

Stantec has reviewed the Watercare application on behalf of the EPA. In its report to the EPA entitled Review of Watercare Services Limited Resource Consent Applications for New Waikato River Take dated 3 February 2021 Stantec has recommended that Watercare provide further information on six matters before its application is publicly notified. One of these matters relates to Hydrology, specifically groundwater as outlined below.

1 T + T, December 2020, Waikato River Water Take and Discharge Proposal- Board of Inquiry-River Hydrology Assessment, prepared for Watercare Services Ltd, reference 1014753. l00vl

Exceptional thinking together www.tonkintaylor.co.nz

---+

Tonkin & Taylor Ltd I 105 Carlton Gore Rd, Newmarket, Auckland 1023, New Zealand

PO Box 5271, Victoria Street West, Auckland 1142 P +64-9-355 6000 F +64-9-307 0265 E [email protected]

APPENDIX C

2

In relation to Hydrology the Report states (at 2.2 Hydrology Review):

We understand from WRC that the take is from the Waikato River catchment not just the Waikato River. The Waikato Regional Plan requires that all takes from the Waikato River catchment, including both groundwater and surface water, are assessed against the WRC allocable flow limits. References to ground water in the AEE relate only to water source alternatives and Watercare's existing water supplies, rather than to any effects on groundwater as a result of the proposed take. It is considered that an assessment of the proposed take on groundwater and groundwater users should be included in the application documents prior to public notification.

The Report recommends (3.0 Conclusion) that Watercare provides, prior to public notification:

Clarification that allocable water is both groundwater and surface water, and an assessment of the effects of the take on groundwater levels and groundwater users.

This assessment has been commissioned in response.²

2.2 Relevant hydrology effects

The T

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The hydraulic analysis indicates mean velocity change (reduction) in the intake reach at the qs4 threshold due to the proposed additional take is no greater than 0.003 m/s, with the

incremental effect on water level being up to approximately 46 mm (during Spring tides). For smaller tides (i.e. less than Springs) the effects will be less.

Further downstream, the effects are reduced. In the lower reaches through the wetlands mean velocity changes at the qs threshold due to the proposed additional take are no greater than 0.001 m/s, with water levels reduced by up to 14 mm incrementally.

The effects of the proposed take on water levels in the river are considered minor given the effects of the twice daily tidal fluctuation at the intake site (which result in tidal induced water level changes up to 1m)...

Salinity intrusion extends from 1.05 km upstream from the river mouth, during mean flow and mean sea level conditions, to approximately 10.3 km upstream, during low flows and high tide.

The analysis, based on sustained qs flows and mean tide conditions, predicts changes in extent of salinity intrusion resulting from the increased abstraction of approximately 150

The magnitude of change in extent of salinity intrusion due to the increased abstraction will be negligible considering the other changes that will affect the flow regime of the lower river, e.g.

due to for instance flows greater than qsand expected sea level rise.

2 This issue was raised informally, prior to the release of the Report in an email dated 23 December 2020, 11:46, Stantec to EPA.

3 T+T, December 2020, Waikato River Water Toke and Discharge Proposal- Board of Inquiry-River Hydrology Assessment, prepared for Watercare Services Ltd, reference 1014753.l00vl

4 The Waikato Regional Plan {WRP) defines the qs as the "one in five year 7-day low flow", that being the "stream flow at any point that has a 20 per cent chance of occurring in any one year (or a likelihood of occurrence of once in every five years, also termed a '5-year return period'). The qs is calculated from the lowest seven consecutive days of flow

in

Tonkin & Taylor Ltd

Further information for pro posed additional Watercare take from Waikato River Assessment of groundwater effects

Watercare Services ltd

5 February 2021 Job No: 1014753.1010

3

This assessment conservatively evaluates the effect of a 50 mm reduction in surface water level on the likely ability of groundwater users to continue to obtain their authorised water supplies and the potential effect on local groundwater budgets. Our assessment assumes that this change will cause a similar change in water table groundwater levels (i.e. up to 50 mm maximum) upstream and downstream of the intake. We consider that this is a "worst case" assessment of decline in groundwater level.

This assessment also evaluates the effect of an increase of 150 min the upstream extent of saline intrusion along the Waikato River under the proposed Watercare abstraction regime. The limit of this saline intrusion occurs amongst the wetlands and islands in the Waikato River reaches upstream of Hoods Landing.

3 Scope

The T

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22 January 2021:

• Based on our experience with other water table systems estimate the effect of an up to 50 mm reduction in surface water levels at Spring high tide - assuming that these cause a similar change in water table groundwater levels.

• Our analysis is based on:

An assumed standardised groundwater pumping well configuration.

An assumed bank profile and topography from the river edge based on readily available topographical information.

Use of standard techniques for modelling phreatic seasonal and pumping drawdowns, and the effect of the reduced river level on these.

• Evaluate the significance of shift inland of the saline front/wedge in the water table aquifer.

• Provide our findings in this short letter report, suitable for submission to EPA/Stantec following Watercare review.

3.1 Groundwater Information

The surface geology in the Lower and Middle Waikato River (LMW) catchment is shown on Figure 3.1 below, sourced from a recent WRC report⁵ prepared by GNS. This summarises the surface geology in the LMW catchment, which comprises the following geological sequences with a brief description of their water-bearing properties:

• Tau ranga Group- which is an important aquifer but has heterogeneous composition and hydrogeological behaviour

• Paka u manu Group - both a fractured and porous aquifer

• Kerikeri Volcanic Group - both a fractured and porous aquifer

• Kaawa Formation important aquifer (porous and fractured, with highly variable hydraulic properties)

• Miocene sediments with limited discrete fractured and limestone water sources

5 Waikato Regional Council Technical Report 2018/33, Groundwater resource characterisation in the Waikato River catchment for Healthy Rivers project ISSN 2230-4363 (Online)

Tonkin & Taylor Ltd

Further information for proposed additional Watercare take from Waikato River Assessment of groundwater effects

Watercare Services Ltd

5 February 2021 Job No: 1014753.1010

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• Te Kuiti Group- with limited discrete fractured and limestone water sources

• Basement- generally not regarded as an aquifer but may have limited discrete fractured water sources.

The primary near surface aquifers along the Waikato River from the proposed intake location downstream to the sea are located within the Tau ranga and Kerikeri Volcanic Group geology. The Kaawa Formation is typically below these two groups, with little or no surface expression. We note that WRC has directed users to take water from this deeper Kaawa Formation, where present, to reduce the risk of surface water depletion or interception that may occur with groundwater takes from the Tauranga or Kerikeri Groups.

N

A

Legend

Simplified model units Tauranga Group

Pakauranu Group Lakes

K

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l

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Figure 3.1: Summary geological map of the LMW area (WRC TR 2018/33}

3.1.2 Groundwater allocation

WRC identifies four assessed aquifers adjacent to and/or downstream of the Watercare intake location. Three are located on the northern side (true right bank) of the river identified as the

6 https://waikatoregion.govt.nz/environment/water/groundwater/pukekohe-groundwater/

Tonkin & Taylor Ltd

Further information for proposed additional Watercare take from Waikato River Assessment of groundwater effects

Watercare Services ltd

5 February 2021 Job No: 1014753.1010

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Pukekohe, Waiuku Discharge Zone, and Waiuku Recharge Zone assessed aquifers. The Pukekawa unit is located on the southern side ofthe river (true left bank). The management level reported for each unit is set by WRC' on a conservative basis considering:

• Average annual recharge over the aquifer

• Area of land above the aquifer

• Distribution of groundwater users.

The management level represents a portion of an aquifer's likely recharge and is used as a trigger point for the setting of a sustainable yield. WRC has stated⁸ that it will review sustainable yields in aquifers when the allocation reaches or exceeds 70 % of the management level (inter alia).

These four assessed aquifers are shown on the WRC figure⁹ included in Appendix A, and details of the existing groundwater management level which guide allocation are tabulated below. In total 14 % of

the

groundwater levels up-gradient considering the typical variations in river level and magnitude of groundwater flows into the river.

3.1.3 Groundwater users

There are 20 groundwater users located within 2 km of river and 2 km upstream of the intake. Of these there are 18 existing consented groundwater takes and two are applications in process. Figure 3.2 shows the intake as a red dot, and groundwater takes within the 2 km buffer as blue dots.

30698

Figure 3.2: Groundwater users within 2 km of the intake or river downstream - blue dots indicate location

7 Waikato Regional Plan, Module 3, Policy 5.

8 Waikato Regional Plan, Module 3, Section 3.3.4.9 Review Allocable Flows/Sustainable Yields

9 Waikato Regional Plan - Water Allocation Maps, Management Level - Assessed Aquifers Chapter 3.3 Table 3-6, Map 5

10 Data extracted from https://www.waikatoregion.govt._nz/assets/RC/Environment/Environmental- indicators/groundwater/gw18.xlsx. which reports allocation as updated to 2019.

Tonkin & Taylor Ltd

Further information for proposed additional Watercare take from Waikato River Assessment of groundwater effects

Watercare Services Ltd

5 February 2021 Job No: 1014753.1010

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The nearest groundw ater take is a take and divert co nsent fo r quarrying activities (de-w atering as w ell as w ater fo r dust suppression and m anagem ent) appro xim ately 1,500 m dow nstream of the intake, on the true left bank.

4 Potential hydrogeological effects of proposed surface water take

4.1 Effect on other groundwater users

Typically, the effect of one groundwater take on another is assessed by pump testing and calculation of drawdown effects during the proposed pumping period.

However, in this case we have assessed the effect of the small reduction in surface water (i.e. less than 50 mm) level on groundwater flowing toward the river and on the potential ability of existing groundwater users to continue to access their supply. We note that contoured groundwater levels⁵ confirm that groundwater flow is generally from higher ground towards the river. We have used specialist hydrogeological judgement to evaluate the potential water level changes at groundwater take locations within the assessed area. As part of this assessment, we have assumed that in a typical situation groundwater takes are from the water table using wells 20 m deep with the following features:

• 4 m depth to static water level, including an allowance for seasonal water level variation.

• A typical in-well drawdown of a further 4 m, which would place the pumping water level at 8 m below ground.

On this basis there is sufficient drawdown still available to account for a potential maximum 50 mm reduction in the level of the water table. This assessment also allows for a submersible pump and 3 m screen in the well.

Based on this assessment existing groundwater users will still be able to obtain their groundwater supplies after Watercare has commenced its proposed water take.

4.2 Effect on saline intrusion

As noted in Section 2.2 salinity intrusion in the lower Waikato River presently extends up to 10.3 km from the river mouth. As a result of the proposed Watercare abstraction regime it is predicted this will extend a further 150 m upstream.

The limit of this saline intrusion occurs amongst the wetlands and islands in the Waikato River upstream of Hood Landing. The process of saline intrusion is caused by sea water moving upstream along the bed of the river beneath and mixing with the fresh Waikato River water. Sea water could potentially then flow into adjacent groundwater. This may occur if the fresh groundwater pressures are less than the equivalent head of sea water on the bed ofthe river.

We note that the surface water level in the river is at or above the sea water level, and that the phreatic groundwater level would generally be at or higher than the river level. Thus, we consider it is unlikely that the predicted small increase in saline intrusion distance would cause a measurable increase in saline water entering the aquifer system.

We also note that there is one groundwater take shown on the true right bank of the river downstream of Hood's Landing. This take is already downstream of the maximum extent of the saline intrusion front. Therefore, we consider that it is unlikely to be affected by a slight change in the location of the front.

Based on this assessment any increase in sea water intrusion into the aquifer is likely to be negligible and would not affect the ability of existing users to take groundwater from the aquifers.

Tonkin & Taylor Ltd

Further information for proposed additional Watercare take from Waikato River Assessment of groundwater effects

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5 February 2021 Job No: 1014753.1010

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4.3 Effect on water budgets

It is conceivable that there might be a slight increase in groundwater flows to the river because of the slight reduction in river level (and thus the slightly increased gradient of the phreatic surface) once the Watercare intake is in operation.

We have assessed the potential change in groundwater flow within 2 km extent of the river. Based on a range of gradients⁵ of the groundwater surface, our estimate is that the change in groundwater flow to the river once the full proposed water take is operational would be less than 1 %. This change is very small, and significantly less than expected changes in river flows as a result of climate variations in rainfall and evapotranspiration.

5 Conclusions

The magnitudes and levels of effects presented below are based on the changes to river hydrology measured against the baseline 150,000 m³/day (net) authorised abstraction.

Effect/ activity Effect without mitigation Magnitude of effects Key mitigation Overall level with no mitigation measures of effect Other Very small (i.e. less than Negligible - no None required Negligible groundwater 50 mm depending on impairment of

users proximity to river) existing users.

reduction in groundwater level at existing bores.

Saline intrusion to Unlikely to cause a Negligible- no effect None required Negligible aquifer measurable increase in on the ability of

saline water entering the existing users to take aquifer system groundwater from

the aquifers.

Water budgets Change is water flows less Negligible - not None required Negligible than 1 % significant compared

to other natural factors that affect the groundwater regime

Tonkin & Taylor Ltd

Further information for proposed additional Watercare take from Waikato River Assessment of groundwater effects

Watercare Services Ltd

5 February 2021 Job No: 1014753.1010

8

6 Applicability

This short report has been prepared for the exclusive use of our client Watercare Services Ltd, 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 being processed by the EPA, to be decided by a Board of Inquiry, and that this report will be used for the purpose of assessing that application.

Tonkin & Taylor Ltd

Environmental and Engineering Consultants

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

Tony Reynolds Senior Hydrogeologist

Tom Bassett Project Director

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Tonkin & Taylor Ltd

Further information for proposed additional Watercare take from Waikato River Assessment of groundwater effects

Watercare Services ltd

5 February 2021 Job No: 1014753.1010

Appendix A: Assessed aquifers near proposed

intake

Waikato

Ia"a

REGIONAL COUNCIL