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Rotorua Te Arawa Lakes Programme – Three Year Plan 2016/2017 – 2018/2019 5

Lake Rotoehu

The short-term interventions for water quality on Lake Rotoehu will continue while land use change agreements are implemented in the catchment and their effects reach the lake. The two short-term interventions planned for Lake Rotoehu to maintain water quality are: weed harvesting and phosphorus locking (alum dosing) as follows:

Table 2 Regional Council Long Term Plan – Rotoehu Funds

2016/2017 2017/2018 2018/2019

Alum Dosing (Deed) $179,000 $181,000 $182,000

Weed Harvesting (Deed) $101,000 $102,000 $103,000

The Rotoehu community are also considering whether they would like a wastewater scheme and how that could be funded. No funds are currently allocated for this purpose in either Council’s Long Term Plan. For the Programme to commit funds to such an intervention a clear water quality benefit would need to be established, the Programme is currently considering what decision-making criteria could be used in these cases.

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Lake Rotoiti

1.1 Ohau Wall

The main intervention for Lake Rotoiti was the construction of the Ohau Wall which was completed in the early life of the programme. However, there are two large pieces of work in respect of the Ohau Wall for the programme in these years:

1 The re-consenting of the wall. The existing resource consent expires in 2017 and a new application needs to be with the consent authority at least nine months prior to the expiry of that consent.

2 The wall has been the subject of serious corrosion and requires protection of the remaining wall to be implemented shortly. A Request for Proposal process is being run currently to establish options and competitive pricing for protection. A preferred option and Business Case will be put to Council in December. Should Council decide to go ahead with protection of the wall, it will need to allocate adequate funds. There is currently no allocation of funds for the protection set aside in the Long Term Plan. However, if the protection goes ahead the estimated cost is $2.5 million and the bulk of the project will be undertaken in the 2016/2017 financial year.

Table 3 Regional Council Long Term Plan - Rotoiti Funds

2016/2017 2017/2018 2018/2019

Re-consenting funds (Deed) $526,000 $329,000 $0

Monitoring (Non-deed) $160,000 $164,000 $169,000

The bulk of the work on re-consenting will take place in the 2016/2017 and 2017/2018 financial years including consultation with stakeholders, final preparation and submission of the application, notification, hearings and, hopefully, resolving any appeals.

1.2 Wastewater schemes

Rotorua Lakes Council have adopted a preferred option for the final reticulation of the Rotoiti lakeside communities Gisborne Point/Hinehopu. Construction of a scheme will occur in 2018/2019 and the following are key activities in the three years of this plan:

2015/2016 - Acquire site for wastewater treatment and land disposal including completion of preliminary design and resource consent application.

2016/2017 - Submissions, hearing and approval of resource consent application. Completion of detailed design of the wastewater treatment plant and land disposal system and Rotoma reticulation system.

2017/2018 - Tendering, construction and commissioning of wastewater treatment plant, land disposal system and Rotoma reticulation system. Completion of detailed design of Rotoiti reticulation system.

2018/2019 - Tendering, construction and commissioning of Rotoiti reticulation system.

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Lake Rotorua

Implementation of the integrated framework, engineering solutions and continued alum dosing on Lake Rotorua will be actions which are the focus of the Programme in the three years which are the subject of this work programme.

The budgets allocated to each of these is set out in the table below, they are indicative and it is expected that change requests will be made to move funds between years, particularly in respect of the Incentives Scheme and the Low Nitrogen Land Use Fund as a better understanding of how they will be implemented is established.

Table 4 Regional Council Long Term Plan – Rotorua Funds

2016/2017 2017/2018 2018/2019

Alum dosing

Ongoing to maintain TLI $748,000 $752,000 $756,000

Gorse

Approximately 10T available plus further investment to secure gains from existing agreements may be required.

$573,000 $355,000 $257,000

Incentives

Target of 100T in lake by 2022 with $40m investment.

$3 million

$500,000 admin

$4 million

$500,000 admin

$6 million

$500,000 admin

Advice and support service

No associated nitrogen reduction but assist landowners affected to develop a Nitrogen Management Plan and access business support for land use change – total spend $2.2 million until 2022.

$818,000 $838,000 $860,000

$3.3 million Low Nitrogen Land Use Fund

Tikitere De-nitrification Plant

The plant is planned for construction in 2018/2019. Activities leading up to construction include consenting, site preparation, detailed design and securing a contractor for construction. Maintenance and lease of the site also continues in the interim. It is expected the plant will provide 20-25T N annually.

$150,000 $500k $4,350,000

Engineering Shortfall –

Budget is provided starting in 2018/2019 to commence other interventions in addition to the Tikitere plant for nitrogen removal. Staff are continuing to investigate options before this money becomes available.

N/A N/A $334,000

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Rotorua Land Treatment System – Rotorua Wastewater Treatment Plant

In relation to moving the wastewater treatment plant disposal site from its current location the following steps are expected (no deed funding currently allocated):

2015/2016 - Agreement and adoption of a preferred option following the completion of a comprehensive consultation process. Completion of preliminary design and submission of resource consent application for the preferred option.

2016/2017 - Submission, hearing and approval of resource consent application.

2017/2018 - Detailed design and tendering of physical works.

2018/2019 - Construction and commissioning.

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Non-Deed lakes

The Regional Council has approximately $70,000 set aside in each year for works that promote sustainable land use in all of the lake catchments, e.g. excluding stock access to water, land retirement and riparian management. It uses these funds (as well as funding staff) to provide advice and financial assistance to landowner and community groups who seek to undertake projects which support sustainable land use. There is also approximately $200k available in each year for projects which protect and enhance biodiversity values in any of the lakes catchments, as well as staff available to assist landowners and community groups with these projects.

There is a budget of approximately $50,000 each year available to support continued water quality monitoring interventions and trials in the Lake Okaro Catchment.

Lake Okataina has approximately $160,000 per year allocated to water quality interventions in that catchment. The use of these funds needs to be considered against the outcomes of the research currently being undertaken in the catchment looking at the sources of nutrient to the lake, particularly from introduced pests. There is also potential for negotiating land use change in the catchment and staff are working through this.

Lake Rerewhaakaitu is a success story in terms of how the whole community have rallied together to own the water quality solution for their lake and take voluntary steps to protect it. The community have signalled their strong support for continuing this work and extending their members to the other surrounding lakes such as Rotomahana, Okaro and Tarawera. The Regional Council has made it clear that it wishes to continue its support for this community effort into the future and has allocated just over $50,000 per year to support community initiatives e.g. continuing to fund an independent facilitator role and contributing towards the construction of detainment bunds on farms.

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14 Rotorua Te Arawa Lakes Programme – Three Year Plan 2016/2017 – 2018/2019

The Regional Council has set aside funds to enable actions in the Lake Rotoma Catchment if necessary. The District Council is also constructing a wastewater scheme there in 2018/2019 with subsides from the Ministry of Health and the Regional Council.

Approximately $77,000 is set aside in the Regional Council’s Long Term Plan in 2017/2018 and 2018/2019 for any action that may be required on Lake Rotoma. A further $93,000 is set aside in 2018/2019 for any phosphorus mitigations that may be required as a result of forestry harvesting expected in the catchment around that time. Water quality in Lake Rotoma remains good and new rules to protect non-Rule 11 lakes are in planning to manage the risk of any land use intensification in

that catchment.

Substantial funds are also set aside over these years to implement actions from the Lake Tarawera Restoration Plan. The Restoration Plan has been notified for public submissions and further work is required with the community before the aspirational plan is adopted. However, in anticipation of actions being required in that catchment to combat declining water quality the Regional Council has set aside in its Long Term Plan approximately $250,000 in 2016/20 17, $207,000 in 2017/2018 and $159,000 in 2018/2019 for interventions in the Tarawera Catchment. A major intervention in the Draft Reconstruction Plan is sewerage reticulation; no funding is set aside in either Council’s Long Term Plan for this. $65,000 is available in 2018/2019 to implement interventions that may be required as a result of monitoring and information gathering work on Lake Rotokakahi which is currently being planned and worked through with that lake’s Board of Control.

The Regional Council in its Long Term Plan has also made a commitment of funds for amenity weed harvesting and control purposes. This investment will be approximately $210,000 per annum for amenity weed control activities across the Rotorua Te Arawa Lakes, which staff are authorised to spend these funds to provide the best amenity outcome. Nutrient gains will be able to be calculated from any removal undertaken.

The Regional Council also has funds set aside for the administration and governance of the programme and ongoing science work, through the partnership with the University of Waikato, which is a critical and substantial under pinning of the Programme.

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File Reference:

4.00909

Significance of Decision: Low

Report To: Regional Direction and Delivery Committee

Meeting Date: 17 November 2015

Report From: Andy Bruere, Lakes Operations Manager

Endorsement of the Tarawera Lakes Restoration Plan

Executive Summary

The target trophic level index (TLI) for Lake Tarawera is 2.6, while its current TLI is 3.1. Provisions of the Regional Water and Land Plan (RWLP) require any lake that is exceeding its 3 year average TLI by more than 0.2 units for more than 2 years must have an action plan to improve water quality to meet the target. Lake Tarawera is required to have an action plan on this basis.

To meet this target, phosphorus must be reduced by at least 1,200 kilograms of phosphorus per year and to cap nitrogen discharges. As water from the seven surrounding lakes (Ōkāreka, Ōkaro, Ōkataina, Rerewhakaaitu, Rotokakahi, Rotomahana, and Tikitapu) drains to Lake Tarawera, these reductions must come from all activities and land-uses in the greater Tarawera System.

The extent of the groundwater boundary is currently uncertain making it difficult to determine the exact nutrient contribution from the outer catchment. A groundwater model is currently being developed which will fill some information gaps. There was an option to delay further development of the Action Plan until the groundwater model became available. However, there is sufficient information to determine an interim reduction target. Some actions, such as sewage reticulation, do not rely on groundwater information. Staff opted to continue development of the Action Plan to ensure restoration of the lake was not unnecessarily delayed.

The Tarawera Lakes Restoration Plan (the Restoration Plan) sets out actions to achieve the interim reduction target of 1,200 kilograms of phosphorus per year and cap nitrogen. The five key actions are:

Action 1 – sewage reticulation of the lakeside community of Lake Tarawera.

Actions 2 and 4 – environmental management plans for all farms in the Tarawera System.

Action 3 – control of silver wattle (aimed at capping nitrogen).

Action 5 – limit on land-use change.

In December 2014 the Rotorua Te Arawa Lakes Strategy Group approved the release of the draft Restoration Plan to the public for feedback. Staff set up a working party of interested

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stakeholders to discuss the draft actions, and the document was released for public comment in May 2015.

There was widespread public support for the actions in the Restoration Plan. The biggest concern was regarding the cost of actions. Funding for most actions is allocated in the Regional Council’s Long Term Plan. However, the estimated $12.4 million cost for sewage reticulation (Action 1) has not been included in the Long Term Plans for either Rotorua Lakes Council or the Regional Council.

Due to the cost and potential impacts on the community, extensive consultation is required between the councils and the community. The Rotorua Lakes Council will set up and administer a steering group to assess options for reticulation and the associated costs.

The final draft of the Restoration Plan is now presented for its final approval. If the Tarawera Lakes Restoration Plan is approved, staff will commence implementation of the actions.

1 Recommendations

That the Regional Direction and Delivery Committee under its delegated authority:

1 Receives the report, “Endorsement of the Tarawera Lakes Restoration Plan”.

2 Endorses the Tarawera Lakes Restoration Plan.

3 Confirms that the decision has a low level of significance.

2 Purpose

The report seeks the endorsement of the Regional Direction and Delivery Committee for the Tarawera Lakes Restoration Plan.

3 Background

The target trophic level index (TLI) for Lake Tarawera is 2.6, while its current level is 3.1. Provisions of the Regional Water and Land Plan (RWLP) require any lake that is exceeding its 3 year average TLI by more than 0.2 units for more than 2 years must have an action plan to improve water quality to meet the target. Lake Tarawera is required to have an action plan on this basis.

Development of the Lake Tarawera Action Plan started in 2006. Staff set up and consulted with the Lake Tarawera Action Plan Working Group and the first draft of the Lake Tarawera Action Plan (the Action Plan) was completed in February 2008.

Before the Action Plan could be released for public comment, the lakes action plans were placed on hold and reviewed by an independent consultant. The review and a recommended streamlined approach were approved by the Strategy, Policy and Planning Committee of the Regional Council in March 2011 and by the Rotorua Te Arawa Lakes Strategy Group (the Strategy Group) in June 2011. Development of the draft Lake Tarawera Action Plan recommenced at this time.

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The draft developed from this point was significantly different to the original draft. This was mostly due to the significant contribution of groundwater and surface water from the seven surrounding lakes (the outer catchment). Actions in the original draft only considered nutrients from within the catchment of Lake Tarawera (the inner catchment). The new draft expanded the scope to include nutrients from in the outer catchment.

However, the extent of the groundwater boundary particularly to the south of Lake Tarawera is currently uncertain, making it difficult to determine the exact nutrient contribution from the outer catchment. A groundwater model is currently being developed which will fill some information gaps.

There was an option to delay further development of the Action Plan until the groundwater model became available. However, there is sufficient information to determine an interim reduction target. Some actions, such as sewage reticulation, do not rely on groundwater information. Staff opted to continue development of the Action Plan to ensure restoration of the lake was not unnecessarily delayed.

Staff held a workshop with Regional Councillors in September 2014 to discuss these issues. The Action Plan was adjusted following this feedback and renamed the Tarawera Lakes Restoration Plan (the Restoration Plan) to better reflect its content and scope.

In December 2014 the Strategy Group approved the release of the draft Restoration Plan to the public for feedback.

4 The Tarawera Lakes Restoration Plan

The draft Tarawera Lakes Restoration Plan is included as Appendix 1. Changes made since December 2014 are shown in red font.

4.1 Reduction target

Because of the interaction between lakes in the area, preparing a nutrient budget and reduction target has been challenging.

A nutrient budget prepared for Lake Tarawera in 2012 estimated nutrient reduction targets for nitrogen and phosphorus. A 2014 review of the budget indicates that the 2012 reduction targets are no longer accurate and places a greater focus on phosphorus than the original targets indicate. This change in the science advice was partially related to concerns over changes to analytical techniques since 2008 and the effect on the nutrient budget.

The recommendation was to focus resources on reducing phosphorus input to the lake by at least 1,200 kilograms per year (kgP/year) while capping nitrogen to ensure further water quality decline does not occur. These are included in the Restoration Plan as interim targets.

4.2 Approach

An estimated 80% of the water flowing to Lake Tarawera is through groundwater. The exact extent of the groundwater boundary is currently unknown however current information indicates that water from lakes Ōkāreka, Ōkaro, Ōkataina, Rerewhakaaitu, Rotokakahi, Rotomahana, and Tikitapu all drain to Lake Tarawera. Groundwater modelling is underway that will fill some of these information gaps.

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In the meantime, it is difficult to identify actions to reduce phosphorus when its source is uncertain. Actions that target only land-use in the inner catchment will not achieve the required reduction and will unfairly impact on those home and landowners. However, it is also unfair to target the outer catchment when the proportion of their contribution is currently uncertain.

Nutrient reductions can have several adverse impacts on the community including a high cost of infrastructure and reduced viability of farms. To ensure that these impacts are shared between all sectors of the community, the required reductions have been distributed as fairly as possible between the outer and inner catchment.

Scientists currently estimate that 57% of the phosphorus that reaches Lake Tarawera is from the inner catchment, while the remaining 43% is from the outer catchment. Required reductions from the inner and outer catchments have therefore been calculated according to the proportion of phosphorus they contribute. All actions will achieve the interim target of 1,200 kgP/year and cap the amount of nitrogen.

4.3 Key actions

There is no one single action that will achieve the target. Any reasonable action that would remove phosphorus was considered during development.

The Restoration Plan contains ten actions that take into account the interim targets and spreads the burden of reductions as fairly as possible across inner catchment and outer catchment, and between urban and rural properties.

Of the ten actions, there are five key actions that will reduce phosphorus and cap nitrogen:

Action 1 – The community of Lake Tarawera is the one remaining lakeside community without reticulated sewage. This action is to investigate options for sewage treatment via a steering group to be set up and administered by the residents and Rotorua Lakes Council. This will reduce phosphorus run-off from septic tanks and promote sustainable lakeside lifestyles. This action will remove an estimated 283 (kgP/year).

Actions 2 and 4 – These actions are both targeted towards farms in the inner and outer catchments to develop environmental management plans. These plans are voluntary and should achieve a combined reduction of 401 kgP/year from the inner catchment, and 516 kgP/year from the outer catchment.

Action 3 – This action will remove 230 kilograms of nitrogen from the catchment through the removal of silver wattle. It also contributes to the aesthetic value of the lake by removing pest plants.

Action 5 – This action would develop a rule to limit land-use change that may increase nutrients to the Tarawera System. No reductions will be achieved by this action, but it safeguards the lake against increased nutrient loading.

The remaining five actions involve further research (including the groundwater investigation) and keeping the community informed. Engineering options such as alum dosing have been included as contingency actions at this stage.

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The key actions are summarised in the table below:

Action Description Catchment Estimated P Reduction (kg/year)

Proportion

1 Wastewater management Inner 283

2 Agricultural land management (inner catchment)

Inner 401

3 Nitrogen fixing plants Inner n/a

Total inner catchment 684 53%

4 Agricultural land management (outer catchment)

Outer 516

Total outer catchment 516 47%

5 Limit land-use change Whole n/a

Total 1,200 100%

5 Community consultation and engagement

During the long development of what is now the Restoration Plan, the community has had several opportunities to comment. Engagement included working parties, public drop in days, workshops, farm visits and meetings. Attendees have included the Department of Conservation, Lake Tarawera Ratepayers Association, Rotorua Lakes Water Quality Society, Fish and Game, Rotorua Lakes Community Board, Te Mana o Ngāti Rangitihi, Tūhourangi Tribal Authority and various independent landowners and residents.

In May 2015, Regional Council staff set up the Tarawera Lakes Restoration Working Party (the working party). Membership of the working party was as broad as possible and kept open to anyone who wished to attend. The main purpose was to discuss the draft Restoration Plan, assess actions and give feedback to improve the document.

At this stage, farmers from the outer catchment had not been approached as the previous action plan had only addressed nutrients from the inner catchment. Staff attended a meeting with landowners from Rerewhakaaitu and Rotomahana catchments to discuss the implications of the actions. Representatives from these catchments also attended a working party meeting in August.

The draft Restoration Plan was released for public comment in May 2015 and the period for feedback closed early July 2015.

Fifty-nine feedback forms were received, with 57 in support of the Restoration Plan. There was widespread support for the key five actions, in particular for sewage reticulation. This action is seen not only as necessary, but urgent. Farm environmental plans are also supported but as a voluntary measure until the groundwater investigation is complete.

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The biggest concern for both sewage reticulation and farm environmental plans is the cost. Some respondents advocate for residents or farmers to meet the full costs themselves, however others support the actions only if they receive financial support.

There was also considerable concern from many farmers who have already carried out protection and environmental work on their farms. In many cases there are few options remaining for further work and their concern was about recognition for the work already done.

Following feedback the Restoration Plan was amended as appropriate.

A summary of feedback and the discussions of the working group are included as Appendix 2.

6 Next steps

If the Committee approves the recommendations, staff will:

• Publish the Restoration Plan as a web based document (limited hard copies).

• Make any minor changes to the document if necessary.

• Start working with farmers on farm environmental management plans.

• Continue work on the land-use change rule to limit new nutrient sources.

7 Financial Implications

Current Budget

Funding for most actions is allocated in the Regional Council’s Long Term Plan. However, the estimated $12.4 million cost for sewage reticulation (Action 1) has not been included in the Long Term Plans for either Rotorua Lakes Council or the Regional Council.

Due to the cost and potential impacts on the community, extensive consultation is required between the councils and the community. A steering group will be set up as part of implementation of Action 1. The steering group will assess options and costs.

Future Implications

Depending on the outcome of steering group discussions, funding for sewage reticulation may need to be included in the next Long Term Plan.

Karen Parcell Natural Resources Policy Manager for Lakes Operations Manager

9 November 2015 Click here to enter text.

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APPENDIX 1

Draft Tarawera Lakes Restoration Plan - October 2015

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Title Title part 2

Tarawera Lakes Restoration PlanOctober 2015

Bay of Plenty Regional CouncilEnvironmental Report

5 Quay StreetPO Box 364Whakatāne 3158NEW ZEALAND

ISSN: 1175-9372 (Print)ISSN: 1179-9471 (Online)

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Summary

Lake Tarawera’s TLI is currently 3.0 and does not meet its target of 2.6. The target TLI was established through a public process and confirmed within the Regional Water and Land Plan.

The main cause of the declining water quality (indicated by a high TLI) is an increase in nitrogen and phosphorus flowing from the catchment. To solve the problem, the level of nutrients entering the lake needs to be reduced to a sustainable load. This involves calculating how many nutrients are flowing to the lake from each source, and estimating the reduction to achieve the target.

The most recent nutrient budget indicates that phosphorus is more of a concern than past nutrient budgets may have signalled. The recommendation is to focus resources on reducing phosphorus, while capping nitrogen, to ensure further water quality decline does not occur.

Therefore, the interim reduction targets are:

• Phosphorus: at least 1,200 kg per year

• Nitrogen: no increase

These targets should be considered the absolute minimum required to improve water quality.

Approximately 44% of the phosphorus flowing to Lake Tarawera is from the seven surrounding lakes. Any restoration scheme to improve Lake Tarawera must consider these outer lakes as well as the inner catchment.

Required reductions from the inner and outer catchments have been calculated according to the proportion of phosphorus that they contribute. Therefore, actions have been selected that require 56% of the required reduction in phosphorus from the inner catchment. The remaining 44% of reductions is assigned to the outer catchment.

The key actions are as follows:

Action Nitrogen reduction Phosphorus reduction

Reticulation of sewage 2,829 kg 283 kg

Better management of agricultural land-use (inner catchment)

n/a 389 kg

Control of nitrogen fixing plants 230 kg n/a

Better management of agricultural land-use (outer catchment)

n/a 528 kg

Develop a rule to limit land-use changes that increase nutrients in the Tarawera System

n/a n/a

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Contents

Part 1: Background 3

1 Introduction 3

2 Background 4

3 Lake characteristics 9

4 Defining the problem 17

5 Solving the problem 22

Part 2: Initial actions 27

1 Target reductions 27

2 Inner catchment 27

2.1 Action 1 – Wastewater management 27

2.2 Action 2 – Agricultural land management (inner catchment) 29

2.3 Action 3 – Control of nitrogen fixing plants 30

3 Outer catchment 30

3.1 Action 4 – Agricultural land management (outer catchment) 31

4 Whole catchment 32

4.1 Action 5 – Limit on land-use change 32

4.2 Action 6 – Groundwater modelling 32

4.3 Action 7 – Cultural health assessment 33

4.4 Action 8 – Geothermal source investigation 33

4.5 Action 9 – Consolidation of science 34

4.6 Action 10 – Informed community 34

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5 Contingency actions 34

6 The Tarawera Lakes approach 35

7 Summary of actions 37

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Part 1: Background

Introduction 1

1.1 Purpose

The Tarawera Lakes Restoration Plan (the Restoration Plan) seeks to identify actions to cap the total nitrogen and reduce total phosphorus concentrations in Lake Tarawera to improve water quality.

1.2 Scope and approach

Lake Tarawera receives the water from all the lakes in the Ōkataina Caldera. Lakes Ōkāreka, Ōkataina, Rotokakahi, Rotomahana and Tikitapu all drain into Lake Tarawera, either via surface water or groundwater flows. Lake Ōkaro and Lake Rerewhakaaitu drain first to Lake Rotomahana, then to Lake Tarawera.

Because of this interaction between lakes the catchment of Lake Tarawera, (the Tarawera System) is made up of an inner catchment and an outer catchment:

• Inner catchment – includes the land, surface water and groundwater that drain directly to Lake Tarawera.

• Outer catchment – includes the land, surface water and groundwater that drain to the seven other lakes in the Tarawera System before draining to Lake Tarawera.

The approach up until now has been to address each lake in isolation, without consideration of the interaction between lakes1. This approach is effective, as a reduction in nutrients in the catchment of any of the outer lakes will benefit both the immediate lake and Lake Tarawera. However, it doesn’t consider the interactions between lakes or Lake Tarawera as the final destination of the nutrients.

Work is also underway to build a groundwater model of the area, which will provide more information on the interactions between lakes. This work is expected to be completed in about twelve months, at which time a more accurate nutrient budget can be prepared with updated reduction targets.

In the meantime, the best information available recommends capping nitrogen at its current level, and focusing resources and effort on reducing phosphorus. Actions to reduce phosphorus will be split between the inner and outer catchment, proportional to the total load contributed by each catchment.

1.3 Community engagement

In April 2015, the Tarawera Lakes Restoration Working Party (the Working Party) was set up to discuss the draft Tarawera Lakes Restoration Plan.

Representatives from a number of established organisations and groups were specifically invited to be members of the working party. Membership was kept open and additional groups and individuals joined as required. Members included iwi and hapū, councillors and staff from the Regional Council and Rotorua Lakes Council, landowners, Rerewhakaaitu Project and the Lake Tarawera Ratepayers Association.

1 Four lakes in the Tarawera system already have approaches in place (Ōkāreka, Ōkaro, Ōkataina, and Tikitapu) and investigations are underway to develop actions for the remaining lakes (Rotokakahi, Rotomahana and Rerewhakaaitu).

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The Working Party discussed the draft Restoration Plan – its approach, science, and actions. Regional Council staff also attended a meeting at Lake Rerewhakaaitu to explain the action plan and its implications to the outer lakes community.

From May to August 2015 the draft Restoration Plan was released to the public for feedback. The Regional Council received 59 feedback forms, 57 in support of the actions in the Restoration Plan. Two submissions were in opposition, specifically to reticulation of sewage in Action 1.

Following a Working Party meeting in August to discuss community feedback, alterations were made to the Restoration Plan.

Background 2

2.1 A brief history

Unless otherwise referenced, the information in this section was sourced from Tarawera: The Volcanic Eruption of 10 June 18862.

Before colonisation, the Rotorua lakes provided food, shelter, economic resources and primary transport routes for Te Arawa. The iwi used Mount Tarawera as a burial ground for chiefs and other persons of importance and the mountain is considered tapu.

Te Arawa is made up of iwi and hapū, based predominantly in Rotorua, tracing their ancestry back to the Arawa waka. Presently, Te Arawa has a population of about 35,1273.

After colonisation, the “Hot Lakes” district attracted tourists from all over the world as stories of the boiling mud, geysers and other geothermal wonders spread. In particular, the Pink and White Terraces (Otukapuarangi and Te Tarata) on the shores of Lake Rotomahana were becoming known as one of the natural wonders of the world. Te Arawa played a major role in developing tourism in Rotorua, and acted as guides for visitors. They kept a significant degree of control over access and transport to the attractions of the area.

Settlers introduced trout and other exotic species into the Rotorua lakes, which depleted indigenous fish stocks and forced a reliance on the introduced species. The introduction of fishing licences led to further hardship for some members of Te Arawa already affected by the reduction of indigenous species.

Over the years, Te Arawa negotiated with the Crown for customary fishing rights, trout fishing licences and burial reserves in the lakes.

Developments in the late nineteenth century led to an increase in nutrients flowing into the lakes from clearing forestry, farming and septic tanks. The environmental degradation of the lakes has affected their mana and wairua4.

2.1.1 Mount Tarawera eruption

Mount Tarawera has three domes – Wahanga (bursting open), Ruawāhia (the split hole), and Tarawera (the burnt cliff). Prior to its eruption in June 1886, Mount Tarawera was believed to be extinct. At the time, most volcanoes in New Zealand other than White Island (Whakaari) and Tongariro were considered dormant.

2 Keam, R. G., 1988 Tarawera: The Volcanic Eruption of 10 June 1886. 3 Statistics New Zealand Census 2006. 4 The New Zealand Government, 2006 Te Arawa Lakes Settlement Act 2006.

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Visitors to the Pink and White Terraces started at the town of Te Wairoa, located at Lake Tarawera. A steep track went from Te Wairoa to Lake Rotomahana for those who hired horses, but the preferred travel route was by boat across Lake Tarawera to Te Ariki and then up the Kaiwaka Stream.

About two weeks prior to the eruption, unusual events created unease. Tourists and locals noticed strange surges in lake level, and at the Terraces there was evidence of recently ejected mud from the geysers.

The most unusual event was the sighting of the waka, or “phantom canoe” as it became known. Eyewitnesses in a tourist boat, both Māori and Pakeha, saw a large war canoe with a high prow and stern being paddled on the main body of Lake Tarawera. The day was clear and bright with no clouds, and they could see the waka and the flashing of the paddles clearly. The canoe did not respond to hails and disappeared around a headland. Local Māori regarded the canoe as an apparition, as they had no waka like the one seen on the lake. Spectral appearances such as this indicated calamity.

Mount Tarawera erupted in the very early hours of 10 June 1886. Strong earthquakes were felt in the Rotorua area and lightning was seen around Mount Tarawera. By 2:30 am all three peaks had erupted, sending ash and smoke thousands of metres into the air. A rift tore open the domes of Ruawāhia and Tarawera and a large new crater emerged at Rotomahana. The Rotomahana crater generated a surge of hot scoria, mud pellets, and balls of fire that destroyed Te Wairoa and other surrounding villages. Buildings collapsed and were buried under mud and ash. Approximately 120 people were killed.

Lakes Rotomahana and Rotomakariri were now one crater which later filled with water to become the present day Lake Rotomahana. There was no trace of the Pink and White Terraces and they were long believed to be destroyed. In 2011, researchers mapping the bottom of Lake Rotomahana found their remnants5. They are now believed to be buried in sediment under the lake, rather than destroyed.

2.1.1 Farming development

In the late 1920s, the land to the south of the lake was identified as third class land, heavily faulted with some steeper contours, bush sickness (cobalt deficiency), and unsuitable for farming. Allen Ford, while hunting, on what was then called Run 78 on the Government maps, saw possibilities for the land as sheep and cattle country. After petitioning the Commissioner of Crown Lands to open this area for farming, Allen Ford, in partnership with his father Henry Ford, were granted a lease for part of Run 78.

Despite its contours, Run 78 was fertile volcanic soil, ranging from medium pumice clay to Rotomahana mud and ash from the recent Tarawera eruption. The biggest drawback to the property was the inaccessibility of water. Although the property has high rainfall (1500 millimetres per year on average) and surface water on two boundaries (Wairua Stream and Rotokakahi) water supply for domestic and stock use had to be pumped 120 m up from the swamp in the lagoon valley, leading to Rotokakahi.

The land was covered in scrub and regenerating forest populated with wild animals, mainly cattle, horses, and deer. The early days of what would become Highlands Station were spent clearing tracks, digging a water reservoir, clearing trees and removing stumps.

All topdressing and sowing was carried out by hand until 1951 when aerial topdressing was introduced. This was a turning point for hill country farms. The farm was connected to electricity in 1954 which allowed the Ford family to live permanently on the farm.

5 www.gns.cri.nz/Home/News-and-Events/Media-Releases/Scientists-find-part-of-Terraces.


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In the 1950s the Government bought land for settlement by returned servicemen and in the 1960s neighbouring farms were developed. The families of these farms, Travers, Keeling, Doney, Ross, Armer and Lambie have been on the land for generations. For all but one, the families that originally purchased the land from the Government are still farming there today.

Although some dairying was carried out on Highlands Station, the contour of the land was better suited to dry stock and in 1961 dairying ceased and the farm became all sheep and cattle. From 1968 and through to the 2001, deer were added to the stock during the venison and velvet boom.

2.2 Te Arawa Lakes Treaty Settlement

On 18 December 2004, a Deed of Settlement was signed between The Crown and Te Arawa for the cultural, financial and annuity redress and the transfer of 13 lake beds to Te Arawa6. These 13 lakes include Lake Tarawera and six other lakes of the Ōkataina Caldera – Ōkataina, Ōkāreka, Rerewhakaaitu, Rotomahana, Tikitapu and Ōkaro. The content of the Deed is enshrined in legislation which was passed in 2006.

The Te Arawa Lakes Settlement Act returns the title of the lakebeds to Te Arawa. This includes the ownership of the lake beds (including plants attached to the lake beds) and the subsoil of the lake. At this stage the water column and the airspace remain in Crown ownership. The water itself is a public asset and continues to be regulated according to the Resource Management Act 1991.

The Settlement Act protects all existing rights, including public access and use of the lakes. Any new structures or modification to existing structures need the consent of both Te Arawa and the Crown.

In 2007, a Memorandum of Understanding (MoU) was signed between the Crown, Te Arawa Lakes Trust, Rotorua District Council and Bay of Plenty Regional Council. The MoU acknowledged, that although the lake beds had been returned to Te Arawa ownership, the water quality was poor and the lakes infested with exotic weeds. It recognised that these legacy issues were created over a long time and that restoration of the lakes would take significant time, effort and financial resources. The MoU also set out the roles for each of the four parties.

2.3 Legislation

In May 2010, the Government released the National Policy Statement for Freshwater Management (the NPS) which was updated in 2014. The policy explicitly requires regional councils to improve the water quality of degraded water bodies and make changes or variations to plans to introduce policies and rules7 to achieve this.

According to the definition in the NPS, most of the Rotorua Te Arawa Lakes are degraded. The Regional Council has also identified the Rotorua Te Arawa Lakes as at risk in the Regional Policy Statement.8The Bay of Plenty Regional Water and Land Plan (the RWLP) contains objectives, policies and methods to specifically address the issue of declining water quality in these lakes.

The Regional Plan for the Tarawera River Catchment (the Tarawera River Plan) has provisions that control activities within the catchments of lakes Ōkaro, Ōkāreka, Ōkataina, Rotokakahi, Rotomahana, Tarawera, Tikitapu and the catchment of the Tarawera River.

6 The New Zealand Government (2006) Te Arawa Lakes Settlement Act 2006. 7 The New Zealand Government (2011) National Policy Statement Freshwater Management 2011. 8 The Bay of Plenty Regional Council (2010) Bay of Plenty Regional Policy Statement October 2014.


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The main focus of this plan is to control discharges in the lower reaches of the river. Many of the provisions have been superseded by the RWLP. The Tarawera River Plan is being reviewed according to the Resource Management Act (requirements for regional plans). The current intention is to incorporate the Tarawera River Plan into the RWLP9, however, the final decision will be made once the review is complete.

Currently, Te Arawa and Affiliate Te Arawa Iwi and Hapū have statutory acknowledgments in place that cover Lake Tarawera and its catchments10. A statutory acknowledgment is a formal acknowledgement by the Crown of the mana of tangata whenua over a specified area. It recognises the particular cultural, spiritual, historical and traditional association of an iwi with the site, which is identified as a statutory area. These statutory acknowledgments require consent authorities, the Environment Court and the Historic Places Trust to have regard to the statutory acknowledgement, to forward summaries of all applications for resource consents to the trustees and enable the trustees and members to cite the statutory acknowledgment as evidence of their association with the statutory area.

2.4 Importance to the community

The community of Lake Tarawera (both permanent residents and visitors) is passionate about the lake and is anxious to keep it in good condition. The aspects of the lake that the community like are:

• Native bush and scenery.

• Water quality good enough to allow fishing, boating and swimming.

• Iconic features like Mount Tarawera and Hot Water Beach.

The community’s main concerns are:

• Declining water quality - once water quality has deteriorated it may never recover.

• Number of pests, both aquatic and land-based (pest trees on Mount Tarawera, catfish, hornwort, rats, wattles, possums, swans).

2.5 Importance to tangata whenua

2.5.1 Māori environmental management

The relationship of Māori and their culture and traditions with their ancestral lands, water, sites, waahi tapu and other taonga is recognised as a matter of national importance in the RMA. The concept of kaitiakitanga and the ethic of stewardship are included as other matters to consider when carrying out duties under the RMA.

For Māori, water is a taonga, a treasure, and is very highly regarded. Māori identify themselves in terms of their ancestors and their rivers and mountains. Māori consider water bodies to be their ancestor, a part of their family and a part of them. When a freshwater body is mismanaged, it hurts not only the water body itself, but the tangata whenua who identify with it.

In the past when travelling away from the coast, Māori relied heavily on freshwater bodies as a source of food including tuna (eels), kakahi (mussels) and koura (crayfish) as well as edible plants. Māori of today still use freshwater bodies as important food sources as well

9 The Bay of Plenty Regional Council (2012) Ten Year Plan 2012-2022 Page 95. 10 The Bay of Plenty Regional Council Nga Whakaaetanga-a-Ture ki Te Taiao a Toi – Statutory Acknowledgments in the Bay of Plenty.


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as for ceremonial purposes. Rivers, lakes and streams are an important part of their cultural heritage and identity.

In Māori environmental management, all resources have mauri (an energy which binds and supports life). The mauri of each water body is a separate entity and cannot be mixed with the mauri of another. This conflicts with the traditional western view that water can be diverted, dammed and used to take away waste. The pollution and alteration of a water body diminishes its mauri and affects its ability to provide food from this source.

Practices, or tikanga, are used to maintain the mauri of resources. The ongoing observation of these tikanga has led to the development of the ethic of kaitiakitanga. Kaitiakitanga is most simply translated as guardianship, but it also includes care, wise management and the use of resource indicators (where resources themselves indicate the state of their own mauri).

The degradation of Lake Tarawera and its surrounding catchments, is of concern to all tangata whenua who are connected to the lake by whakapapa (genealogy) within their rohe. The extent to which the landuse changes and declining water quality has impacted on tangata whenua values is currently unknown. This has been identified in this document as an area for further investigation and action.

2.5.2 Iwi and hapū of Lake Tarawera

This section discusses the issues of the three core iwi and hapū that identify Lake Tarawera as part of their rohe. There are many other iwi and hapū which have an interest in Lake Tarawera who have not been included here.

2.6 Te Arawa

Te Arawa is one of seven Māori Tribes of New Zealand whose rohe extends from Maketū to Tongariro in the central North Island. Te Arawa has a long history with the Rotorua Te Arawa Lakes and Lake Tarawera, as summarised in the sections above.

The Te Arawa Lakes Trust is a partner in the Rotorua Te Arawa Lakes Strategy Group (alongside Rotorua District Council and the Bay of Plenty Regional Council). As a partner, they are committed to ensuring the lake water quality does not decline further, and that action is taken to improve Lake Tarawera.

2.7 Tūhourangi Tribal Authority11

Tūhourangi Tribal Authority was established to manage the Treaty of Waitangi settlement benefits relating to the Hapū of Tuhourangi (part of the Te Pumautanga o Te Arawa settlement in 2008).

Their rohe is from Moerangi (including the Whakarewarewa Forest), Haparangi and Horohoro bluffs to the west, south to Kakaramea (Rainbow Mountain) and east to Ruawāhia (Mount Tarawera). Hapū of Tūhourangi also reside in the Te Puke area.

Environmental concerns include the contamination of the Puarenga Basin, the geothermal fields and the health of waterways, including Lake Tarawera and Lake Rotokakahi.

11 Tūhourangi Tribal Authority (2011) Enhanced Iwi Environment Resource Management Plan.


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2.8 Ngāti Rangitihii12

Ngāti Rangitihi is descended from Rangitihi, the great great grandson of Tametekapua, the commander of Te Arawa Waka. Although he was born at Maketū, he and many of his descendants moved inland to other areas, including Lake Tarawera. They resided at the inland lakes for hundreds of years alongside Tūhourangi and other Te Arawa iwi.

In 1886, the Tarawera eruption caused significant loss of life as well as devastating villages, pā, gardens and the landscape. Whānau gathered at Matatā and travelled inland to look for survivors. The survivors and their whānau settled at Matatā and remain there to this day.

Their rohe covers the Maketū area (the birth place of Rangitihi and the arrival place of Te Arawa waka), the Kaituna River, Lake Tarawera, Tarawera River, Kāingaroa Plains, Rangitaiki River and south to specific places on the Waikato River.

The Ngati Rangitihi Iwi Environmental Management Plan, includes objectives to address the issues of alteration of water bodies and their ability to support fish and bird habitats. The restoration and enhancement of specific water bodies, including Lake Tarawera, is identified as an objective. Other objectives relating to water, concern the issue of the discharge of contaminants and the overuse of finite freshwater resources.

Lake characteristics 3

3.1 The lake today

Lake Tarawera is the second largest lake of the twelve Rotorua lakes managed for water quality by the Bay of Plenty Regional Council (the largest is Lake Rotorua).

At a glance:

• Lake size: 4,138 ha

• Catchment area: 14,472 ha

• Elevation: 298 m

• Average depth: 50 m

• Deepest point: 87.5 m

• Formed: 5,000 years ago

• Outflow: Surface via the Tarawera River

About 391 houses are located at the lake with about 25% occupied all year round by 290 residents. The remaining 75% of houses are used as holiday accommodation. There are anecdotal reports of an emerging trend of bach owners that have been holidaying at the lake for the past few decades, retiring and living at the lake permanently.

Lake Tarawera is a popular lake, providing a variety of recreational uses for residents and visitors:

• Water activities – kayaking, sailing, water-skiing, ski-biscuiting, jet-skiing, swimming.

• Fishing – Lake Tarawera has a well-stocked trout fishery.

12 Te Mana o Ngāti Rangitihi Trust (2011) Te Mahere a Rohe mo Ngāti Rangitihi – Ngāti Rangitihi Iwi Environmental Management Plan.


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• Walking, tramping and camping – there are several walking and tramping tracks around Lake Tarawera with camping grounds located at The Outlet, Humphries Bay and Hot Water Beach.

• Tourist attractions – the Buried Village of Te Wairoa, Hot Water Beach, trout fishing and an ascent of Mount Tarawera attract visitors to the lake.

• General activities – parks and reserves adjacent to the lake provide public facilities such as boat ramps, playgrounds and public toilets.

Map 1 shows the main recreational uses of Lake Tarawera.

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Map 1 Lake Tarawera – Recreational usesLand-use (inner catchment)13

13 McIntosh, J. (2012) Lake Tarawera Nutrient Budget, Bay of Plenty Regional Council.


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The inner catchment includes the land, streams, and groundwater that run directly into Lake Tarawera. Land cover in the inner catchment is mostly native and exotic forest with some pasture as shown in Figure 1 and Map 2 (information sourced from the 2012 nutrient budget).

Figure 1 Graph of land cover in the inner catchment of Lake Tarawera

3.2 Inflows

An estimated 20% of the water entering the lake is from rainfall and surface water flows. Groundwater is the dominant source of inflow to Lake Tarawera with 80% of water entering the lake from sources other than streams.

Surface water flows into Lake Tarawera, predominantly from Lake Rotokakahi via Te Wairoa Stream and from Lake Ōkāreka via the Waitangi Stream. A number of minor inflows also contribute freshwater to the lake, with one stream intermittently sourced from Lake Rotomahana when the lake level is high. Sub-surface inflows connect to Lake Tarawera from lakes Tikitapu, Ōkataina and Rotomahana. Lake Ōkaro and Lake Rerewhakaaitu flow to Lake Rotomahana, then to Lake Tarawera via sub-surface flows.

This represents a particular challenge for the lake, as it can take several decades for groundwater to reach the lake. Any changes made within the groundwater catchment to improve water quality will take many years to show a measurable effect. With the dominant inflow to Lake Tarawera coming from groundwater, the lake will respond slowly to any landuse changes.

Septic tanks are generally closer to the lake edge and their effluent affects the shallow groundwater. The removal of this source would most likely lead to quicker improvements in water quality.

Pasture 1,965 ha

19% Exotic forest

1,524 ha 15%

Native forest 6,421 ha

62%

Other 330 ha

3%

Urban 94 ha

1%

Land-use - Lake Tarawera Catchment


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Map 2 Land Cover in the Lake Tarawera Catchment Environmental Publication 2014/12 - Tarawera Lakes Restoration Plan 13 Page 155 of 436

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3.3 Lake dynamics and sediments

During spring, the water in deep lakes like Lake Tarawera, stratifies into two layers and remains stratified throughout summer and autumn. The layers remain separate until the surface cools again in June of the each year. The bottom layer of water is isolated from the air and oxygen cannot be replenished for the whole nine months of stratification. During this time the decomposition of dead algal cells in the bottom layer uses up the oxygen. There is a risk that with increased algal concentrations, that the bottom layer oxygen could be used up, releasing nitrogen and phosphorus from the lakebed into the water column.

During winter (July to September) the surface waters cool to the same temperature as the bottom waters. All water mixes from top to bottom and any nutrients that have been released from the lake bed during stratification, may be brought to the surface where they can stimulate algal blooms during the following summer. Increased algal growth in the surface waters results in further deposition of algae on the lake bed, further fuelling the cycle. A diagram of this process is shown in Figure 2 below.

Figure 2 Diagram of lake dynamics during mixing and stratification

Currently in Lake Tarawera, there is insufficient algal matter dropping into the bottom layer to use up all the oxygen. However, if water quality continues to decline and algal matter in the lake increases, there may be enough matter dropping into the bottom layer to use all the oxygen during the stratification months. If this happens, nitrogen and phosphorus in the lake bed is released into the water. This leads to an algal cycle as illustrated in Figure 3 (page 17).

Lake Tarawera has the most phosphorus enriched sediments of any of the Rotorua Te Arawa lakes. If the bottom waters of the lake were to become deoxygenated, this phosphorus would release from the sediment and further contribute to the phosphorus levels.


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Figure 3 Nutrient cycling within lakes during stratification

3.4 Outer catchment – the interaction between lakes in the Tarawera System

Lake Tarawera is downstream of the eight lakes in the Tarawera System. Lakes Ōkāreka, Ōkataina, Rotokakahi, Rotomahana and Tikitapu all drain directly into Lake Tarawera either via surface or sub-surface flows. Lake Ōkaro and Lake Rerewhakaaitu drain into Lake Rotomahana, then to Lake Tarawera. The outer catchment of Lake Tarawera is estimated at 50,000 ha and the full extent of the groundwater boundary is unknown. A project is currently underway to investigate the groundwater relationships in the Tarawera System. Map 3 shows the ground and surface water flows as they are currently understood.

Large blue-green algae blooms form by taking

up excess nutrients during summer.

Algae die off and bacteria decompose them. This process

uses oxygen.

Because the bottom waters do not mix with aerated upper waters, all the oxygen in the

bottom waters is used by bacteria.The oxygen demand

causes a number of chemicals bound to the lakebed to be released,

including N and P.

Before winter, the lake water column remixes and new nitrogen and

phosphorus compounds are spread through the lake for algae to use.

The extra phosphorus release favours blue-

green algae (which can ‘fix’ nitrogen) over other

algae.

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Map 3 Ground and surface water flows to Lake Tarawera


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Defining the problem 4

4.1 The target

The Trophic Level Index (TLI) is the indicator used to indicate the health of lakes. The poorer the water quality, the higher the number. The TLI is calculated using four separate water quality measurements: total nitrogen, total phosphorus, water clarity and chlorophyll-a.

• Total nitrogen and total phosphorus are nutrients that plants thrive on. Large amounts of these nutrients in the lakes encourage the growth of algae, which can lead to poor water quality.

• Water clarity is how clear the water in the lake is (measured by secchi disk). Clear water usually means better water quality.

• Chlorophyll-a is the green colour in plants. Knowing how much chlorophyll-a is in a lake gives us a good idea of the concentration of algae in the lake. The greater the concentration of algae, the poorer the water quality.

These four measurements are combined into one number which is the Trophic Level Index.

During development of the Bay of Plenty Regional Water and Land Plan (RWLP), the community set target TLIs for each of the Rotorua Te Arawa Lakes and the RWLP contains objectives, policies and methods, to specifically address the issue of declining water quality in these lakes.

Objective 11 of the RWLP is to maintain or improve water quality in the Rotorua Te Arawa Lakes to meet the TLI for each lake. If the TLI is not met, Method 41 of the plan requires the development and implementation of an action plan to maintain or improve lake water quality to meet the three year average index.14 The target TLI for Lake Tarawera is 2.6. The current TLI is 3.0. Table 1 summarises the most recent TLIs.

Table 1 Summary of TLIs for Lake Tarawera

TLI 2008 2009 2010 2011 2012 2013 2014 2015

Three-year average TLI 2.9 2.9 2.8 2.8 2.9 3.0 3.0 3.0

Annual TLI 2.9 2.9 2.6 3.0 3.0 3.0 3.0 3.1

An increasing trend of phosphorus and nitrogen concentrations was recorded from 1994 to 2008. Since 2009, nitrogen concentration fell, but the phosphorus concentration remains high and is increasing15.

The main cause of the increasing TLI (indicating declining water quality) in Lake Tarawera is the increase in nitrogen and phosphorus flowing to the lake. This is caused by changes in landuse within both the inner and outer catchment of Lake Tarawera. This increase, combined with the characteristics of Lake Tarawera, has the potential to lead to an increase in algal blooms.

14 Environment Bay of Plenty (2008) The Bay of Plenty Regional Water and Land Plan. 15 Scholes, P. (2011) 2010/2011 Rotorua Lakes TLI Update Environmental Publication 2011/1 Bay of Plenty Regional Council.


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Nutrients can take several years to reach the lake through groundwater and surface water. Developments and activities that occurred decades ago have caused the state of the lake that we are measuring today. This means that if no action is taken, and/or further landuse change occurs that increases the nutrients going to the lake, then the lake will not improve or further water quality degradation may occur over the coming decades.

4.2 Nutrient sources

The following sources contribute to the total nutrient load of the lake.

4.3 Pasture

Sheep and beef farming is the main landuse (after native bush) in the Lake Tarawera inner catchment. Nutrient loss comes from a number of sources:

• Erosion and sediment run-off – phosphorus attached to the soil flows to the lake.

• Urine patches and dung – the nitrogen concentration in a patch of urine or dung is far greater than what the grass can use.

• Fertiliser spray drift – application of fertiliser when the soil is waterlogged and excessive fertiliser application, can all cause nitrogen and phosphorus leaching and run-off.

There are four main agricultural landuses in the Lake Tarawera Catchment; mixed scrub/pasture, mixed sheep/beef/deer, beef, and horse/lifestyle grazing. The outer catchment, particularly the land around Lake Rerewhakaaitu, is used for dairy farming. Dairy farming has a much higher rate of nutrient loss than sheep and beef.

4.4 Urban

The predominant source of urban nutrients are septic tanks. The Lake Tarawera community in the inner catchment is the only urban community in the greater catchment that still uses septic tanks.

Most of the homes within the Lake Tarawera Catchments discharge their wastewater to conventional septic tanks. These effectively break down organic matter and filter bacteria as the fluid passes through the ground, but do not remove nitrogen and phosphorus.

The nutrient load from septic tanks is difficult to estimate due to the large proportion of holiday homes at the lake. The average occupancy has been estimated as 775. This amount takes into account the permanent population of 291 and an additional annual visitor load of 484. This number differs from Rotorua District Council’s estimates which are derived from the anticipated maximum load.

The urban area also increases stormwater run-off from the impermeable surfaces such as roofs and roads into the lake, carrying nutrients (and other contaminants like heavy metals) with it.

4.5 Native and exotic forest

Nutrient loss from native bush and scrub reflects nutrient loss to the lake before human activity. Lakes Tarawera, Tikitapu, Ōkataina and Ōkāreka have large proportions of their catchments in native forest.


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Exotic forest includes commercial plantations of trees that are harvested approximately every 30 years. All lakes in the Tarawera System have some proportion of their catchment in exotic forest. Lake Rotokakahi has the highest proportion, with 50% of its catchment in exotic forestry.

4.6 Sewage disposal field in Whakarewarewa Forest

The Rotorua District Council discharges effluent from the wastewater treatment plant to a spray irrigation field in Whakarewarewa Forest. This reduced the nitrogen load to Lake Rotorua from 100 t to about 30-40 t per year.

However, when water quality in Rotokakahi declined, the Whakarewarewa Forest sewage disposal field was identified as a possible source. To investigate this, a bore located between the disposal field and the lake was proposed. Groundwater testing from this bore would have been able to determine whether water from the irrigation field was contaminating Rotokakahi.

Unfortunately, construction of this bore did not go ahead. Instead, the Regional Council commissioned GNS Science to investigate the groundwater from the existing bores in the area, to determine whether effluent from the disposal fields was flowing through groundwater to Rotokakahi.

The study investigated the geology, surface water data, and hydrogeologic data of the area. The findings were:

• Modelled groundwater flows are consistent with the surface water catchments. Water discharged to the Whakarewarewa Forest flows into the Waipa Catchment.

• Most (94%) of the disposal fields are below 394 m, the elevation of Rotokakahi.

• A small proportion (6%) of disposal fields are between 394 and 415 metres. At this height, groundwater is significantly lower than ground level and is lower than 394 m.

The investigation concluded that due to topography and groundwater levels, it is highly unlikely that the treated wastewater from the Whakarewarewa Forest disposal field flows into Rotokakahi.

4.7 Other sources

Other sources of nutrients include rainfall on lake, bare land (Mount Tarawera) and recreation/other grass. Rainfall adds nitrogen and phosphorus directly to the lake from dissolved gases in the air.

4.8 Nutrient loads – inner catchment

The most recent nutrient budget for Lake Tarawera was prepared in 201416. The nutrient budget calculated nutrient inflows to the lake from the inner catchment as shown in Table 2 and in Figures 4 and 5.

16 Hamilton, D. (2014) Memo: Nutrient Budget for Lake Tarawera.


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Table 2 Summary of nutrient sources and loads from the inner catchment

Landuse Rate of loss (kg/ha/year) Total load (kg/year)

Area (ha)

Phosphorus Nitrogen Phosphorus Nitrogen

Pasture

Mixed scrub/pasture 137 0.5 5 68 683

Mixed sheep/beef/deer

1,726 1 10 1,726 17,259

Beef 81 1 15 81 1,217

Horse/lifestyle grazing

21 0.8 8 17 169

Total pasture 1,965 1,892 (42%) 19,328 (29%)

Total exotic forest 1,524 0.18 2.81 274 (6%) 4,283 (6%)

Total native forest 6,421 0.12 3.67 771 (17%) 23,565 (35%)

Other sources

Bare ground 280 1 5 280 1,398

Rainfall on lake 4,139 0.17 3.5 704 14,486

Recreation/other grass

50 0.3 4 14 200

Total other sources 4,469 1,183 (27%) 16,583 (25%)

Urban

Urban (stormwater) 93.5 0.7 3 66 281

Urban (septic tanks) 775 (people)

283 2,829

Total urban 94 348 (8%) 3,109 (5%)

Total nutrient sources 14,473 4,469 kg/year 66,868

(kg/year)


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Figure 4 Graph of total phosphorus load from land-use in the Lake Tarawera

Catchment

Figure 5 Graph of total nitrogen load from landuse in the Lake Tarawera Catchment

Other 1183.1 kg/year

27%

Exotic forest 274.4 kg/year

6% Native forest 770.5 kg/year

17%

Pasture 1892.2 kg/year

42%

Urban 348.3 kg/year

8%

Inner Catchment - Total Phosphorus

Other 16583 kg/year

25% Exotic forest 4284 kg/year

6% Native forest

23565 kg/year 35%

Pasture 19327 kg/yearw

29%

Urban 3109 kg/year

5%

Inner Catchment - Total Nitrogen


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4.9 Nutrient loads – outer catchment

Although information on the outer catchment is still incomplete, it is possible to estimate the contribution of nutrients from the lakes that flow to Lake Tarawera as shown in Table 3.

Table 3 Summary of nutrient sources and loads from the outer catchment

Lake Total load (kg/year)

Phosphorus Nitrogen

Tarawera (inner catchment) 4,690 66,868

Rotomahana (also includes loads from lakes Ōkaro and Rerewhakaaitu) 2,530 18,200

Ōkataina 630 10,500

Rotokakahi 190 3,500

Ōkāreka 110 3,400

Tikitapu 10 500

Buried Village septic tank 18 183

Total kg/year 8,178 kg/year 103,151

As Table 3 demonstrates, the Lake Tarawera Inner Catchment contributes most of the nutrients to the lake. However, a significant proportion comes from the outer lakes, particularly Lake Rotomahana (which, in turn, receives water and nutrients from lakes Ōkaro and Rerewhakaaitu).

Map 4 shows the inner and outer catchments of the Tarawera Lakes System.

Solving the problem 5The solution is to determine the sustainable load for the lake and reduce the inflow of nutrients from sources until the sustainable load is reached.

The 2012 nutrient budget estimated reduction targets for Lake Tarawera as 1,200 kg of phosphorus per year and 12,000 kg of nitrogen per year.17

However, a review of all nutrient budgets indicates that these targets require further review.18 In particular, a greater focus on phosphorus may be necessary than is signalled by these targets. The recommendations were to focus the majority of resources on reducing phosphorus while capping nitrogen to ensure that further water quality decline does not occur as a result of an increase in total nitrogen.

Recent monitoring data show that phosphorus levels are highly elevated relative to nitrogen, water clarity and levels of chlorophyll-a and the levels are higher than previously estimated.

Contributions from the lakes in the outer catchment represent a substantial portion of the total nutrient load to the lake and need to be considered in the Tarawera nutrient budget and targets.

17 McIntosh, J. (2012) Lake Tarawera Nutrient Budget. 18 Hamilton, D. (2014) Memo: Nutrient Budget for Lake Tarawera.


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The high background load from geothermal sources also increases the level of phosphorus in Lake Tarawera. This reinforces the importance of effectively targeting manageable sources of phosphorus to the lake (e.g. septic systems, best management practices on low-intensity farmland, forestry harvesting methods), concurrently with ensuring that increases in nitrogen, which could drive further water quality decline, do not occur.

Therefore, the interim reduction targets based on the best information currently available are:

• Phosphorus: at least 1,200 kg per year


These targets will change when further science is available.

Nitrogen is still an issue for the lake, therefore, some actions are proposed that target nitrogen reductions, but the majority of actions focus on phosphorus.

As the lake is impacted by the surface and groundwater inputs from seven other lakes, the development of the groundwater model is vital in establishing more robust information on water and nutrient inputs and finalising nutrient reduction targets. Until these targets have been developed more thoroughly, the 1,200 kg reduction of phosphorus can be considered the minimum reduction required to stabilise water quality.


Lake Tarawera

Lake Rotomahana

Lake Okataina

Lake Rerewhakaaitu

Lake Rotokakahi

Lake Okareka

Lake Tikitapu

Lake Okaro

1890000

1890000

1900000

1900000

1910000

1910000

5750

000

5750

000

5760

000

5760

000

5770

000

5770

000

Tarawera Lakes Surface Water Catchment

GIS - 501293Sheet 1 of 11.5 0 1.5 3

Kilometres Printed 19/08/2015

Scale 1:125000

Projection and Grid InformationHORIZONTAL DATUM: New Zealand Geodetic Datum 2000

For practical purposes, NZGD2000 equates to WGS84PROJECTION: New Zealand Transverse Mercator 2000

© Bay of Plenty Regional Council, 2015© Sourced from Land Information New Zealand data.

CROWN COPYRIGHT RESERVED

Surface Water CatchmentsTarawera Lakes CatchmentLake Tarawera (inner catchment)Other Lakes (outer catchment)

Land UseNative ForestExotic ForestPastureUrbanOther

¯Map 4 Inner and outer catchment of Tarawera Lakes System

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The solution must also fairly distribute the required reductions between the inner and outer catchments and between urban and rural sources (where applicable). Figure 6 shows the proportion of phosphorus load from the main contributors in the Tarawera System. Contributions from the Buried Village septic tank and from Lake Tikitapu are negligible and have not been included.

Figure 6 Graph of total phosphorus load from lakes within the Tarawera System

Using the proportions as shown in Figure 6, interim phosphorus reductions from each lake can be calculated. These proportions have been taken into consideration when selecting actions (see Action 4).

Once the groundwater model is completed, (Action 6) more detailed information will be available regarding phosphorus sources from each lake. These numbers will be reassessed once this information has been assessed.

Tarawera 4,469 kg/year

57%

Rotomahana 2,530, kg/year

31%

Okataina 630 kg/year

8%

Rotokakahi 190 kg/year

3%

Okareka 110 kg/ear

1%

Whole Catchment - Total Phosphorus


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Part 2: Initial actions

Target reductions 1• Phosphorus: at least 1,200 kg per year


One single intervention focussed on one nutrient source will not achieve the required reduction. To ensure the target is met and that costs are shared across the community, a range of actions have been selected for this document. The estimated cost of each intervention has been included in the key action areas, but where the costs may fall for each intervention has not yet been established. The initial actions have been developed to ensure that reductions in nutrient sources are started but a further review of the necessary actions will take place in 2016, once the groundwater model is available and the source of nutrients to Lake Tarawera is more certain from a revised nutrient budget.

Inner catchment 2Landuse in the inner catchment is responsible for 57% of the phosphorus input to Lake Tarawera. Using the interim reduction target of 1,200, this equates to a reduction of 684 kg of phosphorus per year from the inner catchment.

The two main sources of phosphorus in the inner catchment are urban wastewater run-off from pasture. If reductions are allocated proportionally to their input, urban wastewater should be responsible for removing 106 kg and pasture 578 kg.

The best option to remove phosphorus from urban wastewater is to reticulate (see discussion below) which will remove 283 kg of phosphorus. This proportion is in excess of the urban community’s “share”.

However, it would not be reasonable or feasible to reticulate only that proportion of the community that achieves the fair proportion (approximately 40%). Sewage reticulation will be installed for the entire Lake Tarawera community and remove all the nutrients from this source. The remaining reductions (401 kg/year) will be allocated to the rural sector to achieve.

In future, the reduction target will be revised, and most likely increased. Once urban wastewater has been removed, the responsibility for any additional reductions within the inner catchment will fall to the rural sector.

2.1 Action 1 – Wastewater management

Reticulate houses in the Lake Tarawera urban community and upgrade conventional septic tanks outside the future reticulation zone.

Ensure that existing septic tanks are maintained regularly while options for reticulation are investigated.

• Phosphorus removed: 283 kg

• Nitrogen removed: 2,829 kg


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2.1.1 Background

At present, the 391 houses in the Lake Tarawera community rely on conventional septic tanks to process their wastewater. This community is the only remaining lakeside community out of the eight lakes in the Tarawera System that relies on septic tanks to treat human sewage.

Septic tanks are a source of both nitrogen and phosphorus. The total discharge is 283 kg of phosphorus and 2,829 kg of nitrogen, based on estimated population of 291 permanent residents and 484 visitors.

The preferred option to remove nutrients from this source is to reticulate sewage from all developed properties along the north-western shore of the lake and remove it for treatment at the wastewater treatment plant in Rotorua. This will permanently remove phosphorus and nitrogen from this source.

A steering group, coordinated by the Rotorua Lakes Council is being set up to discuss options for reticulation. The steering group will assess the various reticulation methods and associated costs, as well as investigating funding options.

This work is expected to take several years. With the expectation that reticulation will go ahead, maintenance of septic tanks may not be occurring as required for optimum performance. This is likely leading to increased discharges to the lake and health risks. Therefore, an action to ensure that septic tanks continue to be maintained while reticulation options are investigated.

The option to upgrade properties to advanced on-site treatment systems will not remove phosphorus from this source, and therefore is not a viable option to achieve the target. In addition, these systems require 400 m2 of undeveloped or hard surfaced land for a soakage field and reserve field. On that basis, about half of all sections at the lake would not be able to install these systems19.

2.1.2 Benefits and risks

Reticulation will remove the health issues associated with bacteria and other pathogens that may cause illness being discharged to land near the lake. It also removes the issue of shock loading – when septic tanks left dormant for long periods of time suddenly become active again (e.g. during holidays), sewage may not be treated properly before discharging to the water table.

If reticulation goes ahead, it is likely that the wastewater will be treated at the wastewater treatment plant in Rotorua. Despite the issues associated with transferring the nutrients from one at-risk catchment to another, treating the waste at a modern plant is preferable to partial treatment on individual sites.

2.1.3 Financial cost

Although reticulation is the only feasible method to remove phosphorus from this source, it comes at a high cost. A feasibility study carried out by Rotorua District Council indicates that the total cost will be $12.4 m (plus GST). This equates to $24,453 per house.

The Rotorua District Council or the Regional Council are currently consulting with the community about how and when this will be funded through the Long-Term Plan.

19 Pers comm, Terry Long, October 2012.


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2.2 Action 2 – Agricultural land management (inner catchment)

All agricultural properties within the Lake Tarawera Inner Catchment to have voluntary environmental management plans. farm nutrient plans by 1 December 2016.

• Phosphorus removal target: 401 kg

This target may be revised once further information becomes available.

An environmental management plan is an agreement between the landowner and the Regional Council on what is the ideal nutrient discharge from the property, and sets out a pathway to achieve the required reductions. The environmental management plan must should set out how phosphorus reductions will be achieved.

Environmental management plans may include actions such as:

• Riparian protection – streambanks fenced and planted.

• Land retirement in steep areas.

• Sediment retention structures.

• Phosphorus reduction plan.

This list of actions is not exhaustive and some actions may not be suitable for some farms within the catchment. The Regional Council will work directly with farmers to discuss options for nutrient environmental management plans. These plans will be similar to those developed for the farmers in the Lake Rotorua Catchment, but the focus for this lake is on phosphorus reductions rather than nitrogen reductions.

The basic plans should contain as a minimum, a map of the farm with an explanation of any restoration work carried out and a plan of what work may be carried out in the future. At this stage, the plans will not require Overseer®.

The total reductions from all farms must should be at least 401 kg.

2.2.1 Background

A third of all nutrients leaching to Lake Tarawera from the inner catchment come from agricultural landuse which includes sheep, beef and deer. The Regional Council will work with farmers on voluntary actions to minimise phosphorus run-off from their properties. This builds on actions that farmers have already carried at their own expense, such as fencing and planting of streams, retirement of pasture to native bush, and detention dams in steep gullies.


Other Council programmes have benefited from one on one relationships with stakeholders. These relationships are particularly effective when there are small numbers of stakeholders committed to solving the problem.

Environmental management plans follow this same method of designing a tailored approach for each farm. This allows landowners to choose which nutrient management and reduction options will work best for them and help achieve the overall goal. It builds trust and respect between parties.

However, any reductions in environmental management plans are will not have regulatory support at this stage. If necessary, rules can be introduced to alleviate this risk.


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The cost of employing a consultant to discuss options with landowners and assist with farm nutrient plans is estimated to cost $60,000.

2.3 Action 3 – Control of nitrogen fixing plants

Control nitrogen fixing pest plants in the Lake Tarawera Inner Catchment.

• Nitrogen removed: 230 kg

The Regional Council will work with landowners to target approximately 46 ha of silver wattle over a three year programme. Initial treatment is by stem injection with herbicide. This is followed up after two years to treat re-emergent plants.

2.3.1 Background

Nitrogen fixing plants come from the family of Fabaceae or legumes. These plants use the process of nitrogen fixation to take nitrogen from the air and convert it to a form that is used by the plant. Excess nitrogen is leached into the groundwater so these plants are an additional source of nitrogen.

The current land-cover of silver wattle is estimated at 230 ha throughout the southern part of the catchment. This is estimated to be leaching 1,150 kg of nitrogen per year. The full 230 ha would cost an estimated $805,000 to remove over a three year programme. At this stage, resources are best spent on phosphorus removal. Therefore, only 20% of the 230 ha will be targeted for this phase.


The total cost of removing 46 ha is $161,000.

Removing these plants will also have a beneficial effect on the amenity value of the area. There is little risk in a three year programme to control silver wattle. This is a non-native plant that has little to no amenity value for the area. Provided that landowners are in agreement for its removal, controlling wattle will have more benefits than risks.

Outer catchment 3Land-use in the outer catchment is responsible for an estimated 43% of the phosphorus input to Lake Tarawera. Using the interim reduction target of 1,200, this equates to a reduction of 516 kg of phosphorus per year from the water flowing to Lake Tarawera from the lakes of the outer catchment.

Two thirds of the phosphorus from landuse in the outer lakes catchments ends up in the bottom sediments of the lake. The remaining one third of the phosphorus stays dissolved in water and can flow from lake to lake, eventually reaching Lake Tarawera20.

Therefore, the phosphorus concentration in Lake Tarawera is only one third of the original concentration from the landuse source. The amount of phosphorus in the water flowing into Lake Tarawera is approximately one third of the total amount of phosphorus from the contributing catchment. Two thirds of the phosphorus that reaches the lake is deposited to the lake sediments To reduce phosphorus in the water flowing to Lake Tarawera, the reduction from landuse in the catchments of the outer lakes must be three times the amount of the reduction required.

20 Hamilton, D., Hamilton, M., McBride, C. (2006) Nutrient and Water Budget for Lake Tarawera, University of Waikato.


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Therefore, to achieve a reduction of 516 kg per year, landuse in the outer lakes catchments need to reduce their phosphorus discharges by a total of 1,548 kg.

The main source of phosphorus in the outer catchment is from pastoral landuse. Farms range from dry stock (beef, deer and sheep) to dairy support and dairying.

3.1 Action 4 – Agricultural land management (outer catchment)

All agricultural properties within the Lake Tarawera Outer Catchment to have environmental management farm nutrient plans by 1 December 2020.

• Landuse phosphorus removal target: 1,548 kg (equivalent to 516 kg flowing to Lake Tarawera).

This target may be revised once further information becomes available.

The environmental management farm nutrient plans in this action should follow the same process as those developed for the inner catchment.

The plans must set out how phosphorus reductions will be achieved in the outer catchment and the total reductions from all farms must should be at least 1,548 kg. Note that these numbers are temporary until the groundwater modelling in Action 6 is completed.

The outer lakes should be prioritised and targets allocated according to Table 4, with the largest proportion of phosphorus addressed first. Inputs from Lake Tikitapu and the Buried Village septic tank are negligible and not targeted from reductions.

Table 4 Summary of interim phosphorus reductions from the Tarawera System

Lake Proportion of total (%)

Phosphorus reduction (kg/year)

Rotomahana (also Ōkaro and Rerewhakaaitu) 73 1,130

Ōkataina 18 279

Rotokakahi 6 93

Ōkāreka 3 46

Total 100 kg/year 1,548

As Rotomahana is itself a system of three lakes (water from lakes Ōkaro and Rerewhakaaitu both flow to Rotomahana before flowing to Lake Tarawera), an action plan will be prepared to reduce phosphorus from Rotomahana, taking into account the contribution from the two contributing lakes.

Rotokakahi is currently closed to the public and under legal guardianship of Ngāti Tumatawera and Ngati Wahiao/Tūhourangi. The Rotokakahi Board of Control and Regional Council are working together to draft an action plan.

Lakes Ōkataina and Ōkāreka already have action plans in place and are being implemented. As detailed in Section 6, these will be assessed and updated as part of the Tarawera Lakes System approach. Reduction required from landuse in these catchments will be considered at that time.


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3.1.1 Background

Nutrients leach to Lake Tarawera from the outer catchment from agricultural landuse which includes sheep, beef, deer, and dairy. The Regional Council will work with farmers on voluntary actions to minimise phosphorus run-off from their properties.


This action has the same benefits and risks as Action 2 (above). The cost of employing a consultant to discuss options with landowners and assist with farm nutrient plans for the outer catchment is estimated to cost $120,000.

Whole catchment 4

4.1 Action 5 – Limit on landuse change

Develop a rule to limit landuse changes that increase nutrients in the Tarawera System.

Currently, landuse change in the catchments of any lake in the Tarawera System (except Ōkaro) is a permitted activity under Rule 12 of the Regional Water and Land Plan. A change of ownership and/or economic pressures may drive landuse change. This places the lakes at risk of increased nutrient loading, if land is converted from a low impact activity to a high impact activity. The impact of these higher nutrient activities could completely negate all other actions completed at high cost.

Research and development of these rules has already commenced. Once drafted, the rules will be included in a change to the Regional Water and Land Plan. Any change to a Regional Plan requires full public consultation and input under the Resource Management Act. The change, when prepared, will be notified to the community for submissions.

If necessary, this change will include a regulatory mechanism to reinforce the farm nutrient plans of Actions 2 and 4.

The benefits and risks of rules will be considered as part of the assessment requirements for plan changes under the Resource Management Act 1991.

4.2 Action 6 – Groundwater modelling

Build a model of the Lake Tarawera groundwater system.

The Regional Council will continue with its groundwater investigations to identify relative sources of nutrients from all sources within the Tarawera System.

Drilling and monitoring of the groundwater system of Lake Tarawera has been ongoing for several years. The drilling and testing of groundwater to determine the depth, origin, age and nutrient level of the aquifers in the caldera is completed.

The next phase is to build a model of the groundwater system of the area. This model can then be used to simulate landuse scenarios to determine the potential effect of different landuse changes on Lake Tarawera, and to identify how actions throughout the outer and inner catchments will contribute to the water quality of Lake Tarawera. This information will take some time to process and we can expect a good scientific understanding of the groundwater system by early 2016.

This work is already substantially complete, therefore, an assessment of benefits and risks is unnecessary.


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4.3 Action 7 – Cultural health assessment

Carry out a cultural health assessment of the Tarawera System.

Māori have a distinctive world view that is not necessarily reflected or measured by modern scientific techniques. For generations, Māori have been concerned with the degradation of the waterways within their rohe and have been seeking greater recognition of their cultural beliefs, values and practices.

In 2003, the Ministry for the Environment (the Ministry) developed a model to carry out cultural health index assessments that collected data specific to Māori culture, such as mauri, mahinga kai, wahi tapu and wahi taonga21. A recent assessment on the Puarenga River was carried out by tangata whenua. This assessment adapted the Ministry’s model to assess the cultural health of the river. The report provides an opportunity for the views of the tangata whenua to be heard and recorded, and is an extension of mana whenua and kaitiakitanga.22

A cultural health assessment carried out for Lake Tarawera and its surrounding areas, would provide valuable information on the effects of landuse changes and declining water quality on values. This assessment will also take into account values that are important to Pākehā.

Estimated cost to carry out this investigation is $60,000.

4.4 Action 8 – Geothermal source investigation

Investigate geothermal inputs into Lake Tarawera.

Early estimations of geothermal inputs into Lake Tarawera did not consider them to be a significant source of nutrients23. However, recent evidence suggests that the concentration could be much higher.

Geothermal loads are difficult to quantify because flows may be sub-surface, and geothermal waters also flow to Lake Tarawera from Lake Rotomahana. In 2004, a study by the Department of Chemistry at the University of Waikato, used sodium concentrations to infer the contribution of water sources and concluded that 5-10% of the hydraulic load was from geothermal sources.

Estimated geothermal loads for nitrogen and phosphorus can be calculated by multiplying the observed concentrations with estimated flow. Monitoring of Tarawera inflows found high concentrations of both nitrogen and phosphorus. For example, average concentrations at the geothermal inflow to Hot Water Beach of 0.4 g/m3 of phosphorus Estimated geothermal loads for nitrogen and phosphorus can be calculated by multiplying the observed concentrations with estimated flow. Monitoring of Tarawera inflows found high concentrations of both nitrogen and phosphorus. For example, average concentrations at the geothermal inflow to Hot Water Beach of 0.4 g/m3 of phosphorus and 0.5 g/m3 of nitrogen. All geothermal inflows contribute an estimated 5 tonnes/year of phosphorus and 6.3 tonnes/year of nitrogen.

This is a significant phosphorus load to the lake. One way of addressing this source is to use engineering methods such as dosing, to reduce the phosphorus. There are a number of issues with this approach. First, this is only effective if the sources can be located and if

21 Tipa. G, Teirney, L (2003) A Cultural Health Index for Streams and Waterways –Indicators for recognising and expressing Māori

values, Ministry for the Environment. 22 Tangata whenua (2012) Cultural Impact Assessment – Adverse environmental effects on hapū communities, Tūhourangi Tribal Authority. 23 Hamilton, D., Hamilton, M., McBride, C. (2006) Nutrient and Water Budget for Lake Tarawera, University of Waikato 24 Hamilton, D. (2014) Memo: Nutrient Budget for Lake Tarawera.


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they are not diffused. Sources are easier to treat if they can be identified as coming from a single point.

Another issue is the effects that chemical dosing can have on the lake. It is currently uncertain whether there is a long term effect of this type treatment and investigations are ongoing. There is also the issue of using a chemical treatment to reduce phosphorus while anthropogenic sources continue unchanged.

These implications are currently being explored and will be considered when further information is available.

4.5 Action 9 – Consolidation of science

Summarise science around minor nutrient sources.

The community raised a number of concerns with additional sources that could be contributing nutrients to the lake. These include pine pollen, swans and recreational boating.

The current science around these issues is scattered. This action would investigate and consolidate the science to give the community a clear explanation of minor sources that contribute to the lake.

Estimated cost to carry out this investigation is $10,000.

4.6 Action 10 – Informed community

Keep community informed (in plain English) of science updates and reports when available.

The numbers included in this restoration plan are all interim figures until the groundwater model in Action 6 is completed. Once the groundwater model is available, the target reductions to improve lake water quality will be re-looked at. Current information suggests that further reductions will be required.

The uncertainty around the science leads to concern in the community. Particularly for the farming sector who will be the most affected by any further reductions required. This action keeps the community informed about updates to scientific information when it is available, and in a form easily understandable by most of the community.

Contingency actions

5

Of the several interventions assessed for inclusion in this document, some options were not considered suitable for inclusion. For example, as water quality in the lake is generally good, chemical intervention is unsuitable at this stage.

However, this document was prepared with a number of assumptions including the sewage reticulation project going ahead. If this situation were to change, additional actions may need to be investigated further.

5.1 Engineering solutions

This includes treatment of inflows, sediment capping of the lake bed. These types of interventions have been successful in lakes where water quality was extremely poor, algal blooms common, and rapid intervention necessary (e.g. lakes Rotorua, Rotoiti, Rotoehu). These lakes have improved in a short time due to this type of intervention, and this allows time to develop the long term, sustainable solutions.


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However, scientists are unsure about the longevity of these treatments, but information is growing as the Regional Council’s programme progresses. For a lake such as Lake Tarawera that is generally still in good condition, chemical intervention within the lake is a less preferred option. It may be a suitable option for treatment of geothermal inputs once the investigation in Action 8 is completed, but this will be reassessed at that time.

If monitoring shows that Lake Tarawera is approaching a condition where these actions become more appropriate, they will be investigated further.

5.2 Weed removal

Weed removal targets nitrogen which is not a current concern for Lake Tarawera. It is also not a viable option as the hornwort beds are not of a suitable size or location. Accessing these beds on a regular basis using current technology makes their removal expensive and less effective.

If technology improves and nitrogen removal becomes necessary, weed removal may become a more viable option and can be re-investigated.

5.3 Residential stormwater management

Residential stormwater has been highlighted by the community as an area of concern. This is not a significant source of nutrients to the lake and on its own is not a targeted area for action.

The Tarawera Lakes approach 6Most lakes in the Tarawera System had action plans completed or substantially underway when this document was first drafted. These include:

• Lake Ōkāreka (2004)

• Lake Ōkaro (2006)

• Lake Tikitapu (2011)

• Lake Rerewhakaaitu (implemented by landowners in the catchment)

• Lake Ōkataina (2013)

These action plans were prepared by assessing each lake in isolation and did not consider the interactions between the lakes, or the impact on Lake Tarawera. This approach is suitable at this scale, as each lake must meet its own water quality target.

However, the development process for this Restoration Scheme has shown, that in order to select appropriate actions to improve water quality in Lake Tarawera, all nutrients from the outer catchment must be considered, particularly phosphorus.

Once the groundwater science is complete, this will also provide an opportunity to review the action plans for all lakes in the Tarawera System and potentially consolidate them into a single Tarawera Lakes Action Plan. The Tarawera Lakes Action Plan would:

• Assess current water quality and trends for each lake.

• Reassess nutrient budgets and targets.

• Track progress of actions completed and reductions achieved.

• Assess any further actions necessary to ensure each lake achieves its target.


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• Assess actions necessary to ensure Lake Tarawera achieves its target, taking into account all inputs, including surface and groundwater from the other lakes in the system.

• Consolidate all action plans in the Tarawera System into one document.

In the meantime the Regional Council will continue to implement actions currently included in the lakes’ action plans and will complete action plan development for the remaining lakes (Rotokakahi and Rotomahana). These action plans will be designed, taking into account the Tarawera Lakes approach.


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Summary of actions 7All actions included in the document including expected reductions and estimated costs are summarised in Table 5.

Table 5 Summary of all actions

Actions to reduce nutrients

Action Nitrogen reduction kg/year

Phosphorus reduction kg/year Cost Cost per kgN

and kgP

Action 1 – Reticulate houses in the Lake Tarawera urban community and upgrade conventional septic tanks outside the future reticulation zone.

2,829 283 $12,400,000 (+GST) $43,816 /kgP $4,383 /kgN

Action 2 – All agricultural properties within the Lake Tarawera Inner Catchment to have farm nutrient plans by 1 December 2016.

n/a 389 $60,000* $154 /kgP

Action 3 – Control nitrogen fixing pest plants in the Lake Tarawera Catchment.

230 n/a $161,000 $700 /kgN

Action 4 – All agricultural properties within the Lake Tarawera Outer Catchment to have farm nutrient plans by 1 December 2020.

n/a 528 $120,000* $227 /kgP

Total reduction 3,059 1,200 $12,741,000 $10,618 /kgP $4,165 /kgN


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Actions with no reductions

Action Outcome Cost

Action 5 – Develop a rule to limit landuse changes that increase nutrients in the Tarawera System.

Cap on total nutrients in the catchment will safeguard the lake from increased nutrient loading.

Costs met by other Council work streams or projects.

Action 6 – Build a model of the Lake Tarawera groundwater system.

Better understanding of the landuses that contribute to water quality in Lake Tarawera.


Action 7 – Carry out a Cultural Health Assessment of the Lake Tarawera Catchment.

Better understanding of the interrelationship between lake water quality and tangata whenua values.

$60,000*

Action 8 – Investigate geothermal inputs into Lake Tarawera.

Better understanding of the geothermal inputs into Lake Tarawera.


Action 9 – Summarise science around minor nutrient sources.

Consolidated science around minor sources of nutrients in Lake Tarawera.

$10,000

Action 10 – Keep community informed (in Plain English) of science updates and reports when available.

Well informed and engaged community. No cost

* Includes cost of consultant only. Does not include cost of any nutrient reduction actions identified as a result of the assessment or farm nutrient plan.


APPENDIX 2

Summary of feedback to Draft Tarawera Lakes

Restoration Plan

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Summary of feedback – Draft Tarawera Lakes Restorat ion Plan

Overall summary The Bay of Plenty Regional Council (the Regional Council) received 59 feedback forms. Fifty-seven feedback forms were in support. The support ranged from complete support of actions, to conditional support (eg. the action is supported provided financial assistance is available).

Two submissions were in opposition and this opposition was to the sewage reticulation.

There was a split between urban and rural feedback. Farmers are concerned with the agricultural actions while those in the urban community gave feedback on the sewage reticulation.

The feedback is summarised in the sections below. On 4 August 2015, the Rotorua Lakes Restoration Working Group discussed the feedback at their meeting. This working group is made up of interested members of the community. Comments from the working group, and the outcome of all comments are included at the end of each section.

Feedback Urban sewage reticulation – Action 1

Summary of public feedback

The feedback shows widespread support for sewage reticulation of the lakeside community. This action is not only supported but seen as urgent, and should not wait until the groundwater model is built.

The biggest concern regarding reticulation is the cost and this is where the community is divided. There are those that believe residents should pay for the system themselves, and others that want regional and national support.

One argument for government support is that the lakes are a regional and national treasure therefore the wider community should also contribute to its improvement. However, most of the rationale for external funding is based on fairness – that this community should receive financial support to the same or similar extent as other lakes communities have received.

In opposition was that private benefits of having a property at Lake Tarawera were significant and these reflected property values. Those who own these high value properties should therefore pay to improve their wastewater, not expect the wider community to subsidise. Council’s role in this scenario is to investigate innovative funding options to assist those who will face financial difficulties.

There was also feedback in opposition to the buried village septic tank not being included in actions. The reason for this opposition was that everyone has to do their part to fix the lake.

The two feedback forms in direct opposition to the plan were specifically focussed on sewage reticulation. The main reasons were that it is an expensive action for little gain to the lake. Alternative sewage plans were suggested, such as installing ozone purification units at the outlet of every septic tank which will achieve the same result for fraction of the cost.

Comments from working group

• Discharge of sewage into lake and then taking water from same source has health issues.

• Sewage reticulation may increase property values around lake – reason for why cost should be shared – other lakes had deals such as some level of subsidy. Precedent from subsidy set at other lakes.

• No subsidy earmarked for this lake in either council LTP. Councils have been lucky so far that central government has had funds available. It is getting harder to get funding for these things both from central government and local government.

• We can estimate costs but largely unknown until system decided and job goes up for tender.

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• Sewage treatment no longer about just getting rid of waste, but stripping nutrients for water quality so cost increases. If no support from central government then it falls on ratepayers.

• Has water quality improved around lakes with sewage reticulation – another question is what would have happened if they didn’t get reticulation – University of Waikato is looking at this. Anecdotal evidence is that property values have improved from having sewage reticulation.

• But if we’re spending lots of money on scheme for little nutrients out, it’s a waste of money – can we get these out a better way. Cost of reducing phosphorus from other method comparison. This question comes up all the time is it worth it. Discussion was, yes it’s expensive, but a modern society should have sewage reticulation. In general people know it’s expensive but believe they should have reticulation, and having some financial support makes it more palatable.

• Is an issue of fairness, other lakes have had the support. Paying high rates and don’t have a number of amenities that others have (eg. footpaths, water, lighting, wastewater etc).

Overall outcome from feedback and discussion

Support for sewage reticulation but concern around cost. This is a matter that will be discussed in the steering group set up for this purpose.

Agriculture – whole catchment – Actions 2 and 4

Summary of public feedback

Voluntary farm nutrient plans are supported but as a voluntary measure until groundwater studies are complete. Opinions are divided once again on where costs should fall, and the timing for when they should be completed.

Some feedback is that farmers should pay for their own farm nutrient plans. Others believe that while land owners should pay their share, because the lakes are a regional and national treasure, council and government need to contribute financially.

There is concern regarding the short timeframes for developing the plans. This could result in a rush to meet the deadline with substandard plans. It would be better to give sufficient time for farmers to develop high quality nutrient plans that would benefit the lake. Opposing opinion is that the timeframes are too long and should be shortened.

There was also considerable concern about recognition for the work that has already been done. Infrastructure is expensive and a lot of restoration and environment work has already carried out. There are few options remaining for further work.


• Rerewhakaaitu farmers have just been through this process and set up a farm nutrient plan – it takes a while to everyone’s buy in. Involved someone in the field talking to all farmers and went through options for farms and farmer agreed what they could do and farmer signed off.

• Currently we’re unsure of what the adverse effect is from outer catchment – farm nutrient plans what problem are they solving.

• Prior to Tarawera plan, farmers were aware of runoff to Tarawera from outer catchment – just didn’t know how much – farm nutrient plans were intended to fix Rerewhakaaitu without regard to Tarawera

• Tripling of P leaching from outer – not enough pasture to retire –until we have science we don’t know what that means.

• Farm nutrient plans are a part of the future, farmers need to get up to speed and get FNPs.

• Equity issue – asking for residential people to pay for reducing load, so want to know that everybody else is doing their fair share of reductions

• Reductions made can be undone by new operator coming in at high intensity

• Best to have one agency doing the process

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• It is feasible – reflection of what has already been done

• Need example – who’s going to see and audit it, on the table before we can decide what is needed and how long it will take. The information in the FNPs shouldn’t be open to the public

• Why have a timeframe at all if voluntary?


Support for voluntary FNPs but not for timeframes. This support is conditional on what exactly is required, who will see it (preference that they are not made public), who audits (eg. third party).

Since the working party meeting further feedback from farmers in the outer catchments have requested that the due date remains at 2016 and that they pay for their own plans.

Agriculture – outer catchment – Action 4

There was additional feedback from the agricultural sector specific to the outer catchment.

One concern was that the outer catchment has not been consulted on early enough and while farmers in this area are committed to decreasing environmental impact they are is now overwhelmed by this new plan. The Regional Council needs to ensure they are actively involved from now on.

There is also concern about the science used, first to allocate P reduction to the outer catchment, then to allocate the bulk of that reduction to three lakes. The science needs to be robust.

Some feedback was that the outer catchment should be the main priority. The reason for this is that sewage reticulation has not improved water quality in Lake Ōkāreka and this is felt to be because there is insufficient rural land management. Lake Tarawera has two outer lakes with declining water quality and dairying intensification. This will exacerbate the water quality degradation.


• If numbers left in clearly state that they are conditional and subject to change

• Because of late notification to outer timeframe for delivery should be reassessed.

• See as frequently as possible progress of science – communication as often as information available and technical reports translated to layman’s terms

• Add another action to keep community informed on science as often as possible and understandable in layman’s terms.


Allocation numbers are fine provided it is clear that they are conditional. Additional action required regarding ongoing community engagement.

Nutrient capping – Action 5

There are conflicting opinions on capping rules. Some believe that rules are not conducive to cooperation between council and landowners unless the council has already tried collaboration. However, others see rules as necessary to ensure all landowners cooperate.

Again, there was concern with consultation, particularly with landowners in the outer catchment. Consultation on any capping rules is key and needs to be started early.

There is concern with constraining future land use with capping rules as drystock farming relies on dynamic mix of farming different livestock classes and crops. The cap needs to be science based or farm values could erode.

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• This is urgent – won’t take many hectares converted to dairying to undo everything - hard work of number of years

• Some initial investigations done by council staff – based on high level activity – eg. dairying can go down to dry stock or dry stock to forest but not the other way – not an Overseer benchmark

• Needs a clear explanation of what capping means – can be a fearful word

• Difficult to come up with solution across all land uses, and equitable, some who have been polluting for years, those who haven’t can’t change their use and improve business even though they haven’t been polluting

• Limit on land use change – maybe a better way to describe

• Concern with more intensive farming on land classed as 6 and 7 land where not ideal

• Forestry land has to stay as forestry but no recognition for intensification of current land use

• What is fairer is no change – which means benchmarking

• Fear is when science comes back, will it mean reductions, not just caps

• Consultation important with all landowners – land values drop and rent values drop


Urgent and supported but we need to make sure it is consulted on and a system used that is as fair as possible.

Other actions

There was general support for groundwater work, the cultural impact assessment, and for the reassessment of all action plans.

There was also a request for gorse control/eradication, however another comment concerned the action to control nitrogen fixing plans. As the main issue identified in the plan was phosphorus, the query was whether this was an aesthetic action.

Feedback suggests using alum dosing as a short-term fix while long-term solutions are put in place.

There was some feedback concerned with the high cost and minimal benefit from actions.


• Geothermal is a big contributor – unsure of how much though

• Climate this year Lake Rotorua – very settled weather and high temperatures. Lake Rotorua stratified and was anoxic for one month. Unusual summer with high temperatures causing blooms. Lake Tarawera isn’t anoxic during stratification

• Unusual blip in P could possibly be drought related. The theory is that water level drops and changes soil then during winter highs so more flushing of P because of dry summers.

• At this stage not appropriate for alum dosing and it would take a really good case to dose Lake Tarawera – partners in the lakes strategy group may be okay with Lake Rotorua but not Lake Tarawera

• We would need to look at science of geothermal inputs and consider whether we would dose it, is it emotional that stops us doing this type of thing – we need to wait and see what the science is and have discussions.

• Dosing is temporary and may not be appropriate for Lake Tarawera which is a deep lake


We need to investigate geothermal sources. Other methods, such as alum dosing should be re-looked at once science is complete.

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Other concerns

There were several concerns that fall outside the scope of the restoration plan. These include:

• Urbanisation of the lake edge – should we cap the number of houses?

• Recreational use of the lake – Tarawera Trail and boating which contributes uncontrolled sewage. Are any of the algal blooms associated with high number of boats?

• Public toilets are smelly and not working properly

• Claims that the Whakarewarewa disposal field from RLC wastewater treatment plant is contributing to the nutrient load to the lake

• Pollen from exotic forests contributes nutrients

• High swan population contributes to nutrients

There were also a number of general comments and questions not related to specific actions as follows:

• Water quality is of importance to Maori but also many non-Maori

• No mention of health risk of swimming and drinking lake side water contaminated with septic tank discharge

• Discussion of climate change and how it may be affecting thermocline needed

• Clearer explanation of why phosphorus and not nitrogen.

• Define the inner and outer catchments more accurately

• A better understanding of all causes.

• Funding for investigation of geothermal inputs

• Is there a measurable improvement in lake quality in the lakes which have implemented sewage system

• How confident are we that these actions will achieve TLI of 2.6

• Are the P reduction targets attainable and realistic

• Lack of in depth information in plan – no one really knows what they are signing up for

• Once groundwater studies completed the nutrient limits need to be updated

• We need a non-technical explanation of phosphorus cycle – many don’t understand that it can dissolve into lake water and move from lake to lake. Also, when the groundwater modelling comes out, a non-technical explanation alongside would be really helpful


• Maintenance of septic tanks – if it’s going to take a while to reticulate then this should be followed up

• Extra actions - Further consolidation of science around these issues – how much do we know

• Timeline of actions – diagram to link community groups, councils, strategy groups etc


Further actions required:

• Timeline of actions.

• Diagram to show links of groups.

• Action to consolidate science around concerns listed above.

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File Reference:

1.00062

Significance of Decision: Receives Only - No Decisions

Report To: Regional Direction and Delivery Committee

Meeting Date: 17 November 2015

Report From: Ken Tarboton, General Manager Technical Services

Rotorua Lakes and Maritime Operations Asset Management Plans

Executive Summary

The purpose of this report is to present the draft Rotorua Lakes and Maritime Operations Asset Management Plans for adoption. These plans have an operational focus that directs how Council’s key Rotorua Lakes and Maritime Operations assets are managed over their useful life.

The AMPs align with Council’s 2015-2025 LTP and fulfils the requirements of Schedule 10 of the Local Government Amendment Act 2002. They also provide a formal performance monitoring and reporting framework to demonstrate that the activities are meeting their obligations.

Executive summaries of the Rotorua Lakes and Maritime Operations AMPs are attached for consideration by the Committee. Copies of the full AMPs are available on request.

1 Recommendations

That the Regional Direction and Delivery Committee under its delegated authority:

1 Receives the report, Rotorua Lakes and Maritime Operations Asset Management Plans.

2 Adopts the draft Rotorua Lakes and Maritime Operations Asset Management Plans.

2 Introduction

The purpose of asset management is to provide:

“a desired level of service through the management of assets in the most cost-effective manner for present and future customers” (Audit New Zealand).

Council has adopted a systematic approach to the long-term management of its assets and services and is committed to best appropriate practice asset management in order to achieve the following key objectives:

Meet the service expectations of stakeholders.

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2

Ensure capital projects and maintenance activities achieve efficient results that align with required outcomes.

Demonstrate Council’s approach to managing risk and working towards a sustainable future.

Comply with all statutory requirements.

A recent gap analysis was carried out to determine the current level of asset management across Council and within each asset management activity area. For the Rotorua Lakes and Maritime Operations activities the main improvement gap was the development of ‘core’ AMPs. This was agreed and recognised by Council with the budged approved in the TYP 2012-2022.

Council currently has three operational AMPs, one for each of Rivers & Drainage; Property and Regional Parks activities. Adopting the Rotorua Lakes and Maritime Operations AMPs will increase the number of Council adopted asset management plans to five.

3 Purpose of these plans

The purpose of the Maritime Operations and Rotorua Lakes Asset Management Plans (AMPs) is to outline the management of the activities’ asset portfolios in the most cost effective and sustainable manner to meet the levels of service required under the activities.

The AMPs align with Council’s 2015-2025 LTP. The LTP sets the levels of service and budget framework for the assets, while the AMPs set out how the assets will be managed and maintained. The AMPs also provide a formal performance monitoring and reporting framework to demonstrate that the activities are meeting their obligations.

The AMPs will be revised annually with full three yearly reviews under the LTP process to incorporate and document changes to works programmes, outcome of service level reviews and new knowledge resulting from the AMP improvement programme.

4 Rotorua Lakes Activity

Council manages 12 lakes under the Rotorua Te Arawa Lakes Programme activity, which focuses on water quality protection and restoration. Council manages $11.7 million of assets to implement the goals of the Rotorua Lakes Strategy. The assets under the Rotorua Lakes activity are very unique, ranging from floating wetlands to Phosphorous-Locking plants with the main asset being the Lake Rotoiti Diversion Wall.

5 Maritime Operations Activity

The Maritime Operations Activity ensures navigational safety and maritime oil spill response is provided 24/7 in the Bay of Plenty region. Council currently manages and maintains approximately $1.8 million worth of Maritime assets. These assets range from moorings and specific navigational aids (lights, beacons, buoys, markers and signs).

Executive summaries of the Rotorua Lakes and Maritime Operations AMPs are attached for consideration by the Committee. Copies of the full AMPs are available on request.

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6 Financial Implications

The Rotorua Lakes and Maritime Operations Assets Management Plans were funded from within the 2013/2014 and 2014/2015 Corporate Improvement budget.

For the Rotorua Lakes AMP this includes consultancy fees of $26,388 for the following services:

Darroch Limited (registered valuation of assets)

Elevate Solutions Limited (AMP assistance).

Audit New Zealand (final review of draft AMP)

For the Maritime Operations AMP this includes consultancy fees of $25,858 as follows:

Beca Limited (registered valuation of assets)

Elevate Solutions Limited (AMP assistance).

Kirsty Brown Asset Management Officer for General Manager Technical Services

9 November 2015 Click here to enter text.

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APPENDIX 1

Rotorua Lakes Asset Management Plan Draft 2015

Executive Summary

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Rotorua Lakes Asset Management Plan

Executive Summary

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Rotorua Lakes Asset Management Plan Executive Summary – June 2015 i

Document Control

Document Information

Document name: 2015 Rotorua Lakes Asset Management Plan Executive Summary – June 2015.

Programme responsibility Rotorua Te Arawa Lakes Programme.

Status: For Council to approve.

Document review and history

Author Description of change Date Version

Kirsty Brown Review by Organisational Asset Management Steering Group

15/09/2015 1.1

Future review

Review timeframe: 2017/2018 In line with the requirements of Council’s Long Term Plan.

Distribution control

Person Role Date of issue Version

Kirsty Brown Asset Management Officer 1.0

Reviewed:

Signed: .......................................................... Date: ......................................

Kirsty Brown Asset Management Officer

Signed: .......................................................... Date: ......................................

Helen Creagh Rotorua Catchments Manager

Approved for issue:

Signed: .......................................................... Date: ......................................

Warwick Murray General Manager Environmental Services

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ii Rotorua Lakes Asset Management Plan Executive Summary – June 2015

Asset Management Team

Bay of Plenty Regional Council Rotorua Lakes Asset Management Team

Warwick Murray General Manager Environmental Delivery

Helen Creagh Rotorua Catchments Manager

Andy Bruere Lakes Operations Manager

Niroy Sumeran Lakes Operations Officer

Janine Barber Senior Environmental Scientist

Kirsty Brown Asset Management Officer

This is the first edition of the Rotorua Lakes Asset Management Plan.

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Rotorua Lakes Asset Management Plan Executive Summary – June 2015 iii

Contents

1 Introduction 1

2 Purpose of this document 3

2.1 Asset management objectives 3

2.2 Plan timeframe 3

3 Strategic environment 4

3.1 Purpose 4

3.2 Rotorua Te Arawa Lakes Programme Vision 4

3.3 Community Outcomes 4

3.4 Rationale for Council’s involvement 5

3.5 Programme’s objectives 6

3.6 Levels of Service 7

4 Business overview 7

4.1 Funding and expenditure 7

5 Major capital works programme summary 8

6 Risk Management 8

7 Lifecycle Management 8

8 Asset summary 9

8.1 Phosphorus locking (P-locking) plants 10

8.2 De-stratification plant (Lake Rotoehu) 10

8.3 Tikitere zeolite plant – Lake Rotorua 10

8.4 Water quality monitoring buoys 11

8.5 Koaro fish pass/trout barrier 12

8.6 Ohau diversion wall 12

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iv Rotorua Lakes Asset Management Plan Executive Summary – June 2015

8.7 Wetlands 13

8.8 Groundwater monitoring bores 14

9 AMP review 14

10 Improvement Plan 14

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Rotorua Lakes Asset Management Plan Executive Summary – June 2015 1

1 Introduction

This Asset Management Plan (AMP) Executive Summary describes how Bay of Plenty Regional Council (BOPRC) manages 12 lakes on behalf of the community via the Rotorua Te Arawa Lakes Programme. These lakes are of regional and national significance as well as being a taonga to the people of Te Arawa.

Improving the health of these lakes is of key importance and has been a significant driver in the capital works and stakeholder engagement that has taken place so far (see the Levels of Service (LoS) and Lifecycle Management (LCM) sections for more information).

The 12 lakes that are considered as part of this Asset Management Plan (AMP) are outlined in Table 1 and the assets they contain and their location as shown in the map on the following page. Deed funded lakes are those out of the 12 lakes that have been identified as the most in need of action and has Crown funding (as formalised under a Memorandum of Understanding dated 18 April 2007) towards improving their water quality, subject to BOPRC and Rotorua Lakes Council (RLC) matching the Crown’s contribution.

Table 1 Lakes covered under the Rotorua Te Arawa Lakes Programme.

Deed funded lakes Non-deed funded lakes

Rotorua Tikitapu

Rotoehu Ōkataina

Rotoiti Rotokakahi

Ōkāreka Tarawera

Okaro

Rotomā

Rerewhakaaitu

Rotomahana

The physical assets managed by Council for the Lakes activity is shown in Table 2:

Table 2 BOPRC Assets for the Rotorua Te Arawa Lakes Programme.

Asset Replacement Value

P-Locking plants: One at Lake Rotoehu, two at Lake Rotorua $1,092,800

Zeolite plant: Lake Rotorua $469,400

De-stratification plant: Lake Rotoehu $456,600

Fish passage: Lake Rotorua $26,000

Monitoring buoys: Lakes Rotorua, Rotoiti and Rotoehu $204,500

Wetlands: Lakes Okaro and Rotoehu (floating) $1,119,200

Groundwater monitoring bores: Lakes Rerewhakaaitu, Ta $1,353,218

Diversion wall: Lake Rotoiti. $11,368,500

Total Asset Replacement Value $16,090,218

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