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3 Leadership and responsibility for lakes management - Environment Bay of Plenty and Rotorua District Council

New Zealand is a leader in natural resource management having recognised early, by world standards, that effective management of our precious natural resources (land, soils, water, lakes, rivers, estuaries, oceans, vegetation and animals) needs a co-ordinated and integrated approach. Through its Resource Management Act, New Zealand has established a number of processes to achieve this approach, including the establishment of 16 regional councils to achieve integration at the regional level.

Environment Bay of Plenty (EBOP) is the council charged with overall water quality and catchment management of the Rotorua lakes as part of its broader role in sustainably managing all of the natural resources in the Bay of Plenty region. The Rotorua District Council (RDC) plays an important role in land use planning and management, including certain specific aspects such as sewerage and urban stormwater management.

3.1 Regional management framework - the Proposed Regional Water and Land Plan

Management of the Rotorua lakes, and especially Lakes Rotorua and Rotoiti, come under the Regional Water and Land Plan. This is nearly completed after an extensive public consultation period although the decisions of the Council will still be open to appeal. This comprehensive plan covers management of land and water resources under the Resource Management Act 1991, including:

  • land and water integration
  • discharges to water and land
  • beds of rivers, streams and lakes
  • geothermal resources
  • wetlands
  • regional rules
  • financial contributions
  • information to be submitted with resource consent applications
  • anticipated environmental results
  • cross boundary issues
  • plan review process.

Figure 1. Rotorua lakes and their catchments

Map showing location of Rotorua lakes and their catchment areas. See this figure at its full size.

The Proposed Regional Water and Land Plan (the Water and Land Plan) covers all the area in the Bay of Plenty Regional Council boundary, excluding the coastal marine area, the areas covered by the Operative Rotorua Geothermal Regional Plan and the proposed Regional Plan for the Tarawera River Catchment, which is shortly to be made operative. The Water and Land Plan covers land (including soil), water (including rivers, streams, lakes, wetlands, modified watercourses and groundwater) and geothermal resources in the Bay of Plenty. It addresses issues relating to the adverse environmental effects of the use and development of land, water and geothermal resources that are within the scope of EBOP's functions and responsibilities under the Resource Management Act 1991.

The purpose of the Plan is to achieve the following aims:

  1. promote the sustainable management of land, water and geothermal resources
  2. achieve the integrated management of land and water resources
  3. maintain or improve environmental quality in the Bay of Plenty region
  4. protect existing high quality environment and resources
  5. protect sensitive receiving environments
  6. sustain the life-supporting capacity of soil, water and ecosystems
  7. maintain or enhance the heritage values of land, water and geothermal resources
  8. establish appropriate environmental standards to achieve c) to f)
  9. address the adverse environmental effects of the use and development of land, water and geothermal resources
  10. take a permissive approach to the use and development of land, water and geothermal resources where it is consistent with a) to g).

The links between the identified values and environmental standards are set out in a useful figure on page 4 of the proposed Plan.

Considerable attention is paid to the strong relationship of the Māori people to the land and waters and the concepts of kaitiakitanga and mauri. Section 2 of the proposed Plan begins with a quote of the Māori aphorism, "Mankind perishes, the land remains eternal", as this epitomises Māori beliefs on kaitiakitanga or guardianship of the land and its resources.

Broadly speaking kaitiakitanga involves a wide set of practices based on a world and regional environmental view that includes the ideas and principles of:

  • guardianship
  • care
  • wise management
  • that the condition of the natural resources indicates the state of their own mauri
  • maintenance of the spiritual and cultural aspects of the natural resources
  • protection, enhancement and restoration of the mauri
  • appropriate development of resources where necessary.

As mentioned earlier, mauri is the life force present in all animate and inanimate objects. It binds one resource to every other element in a natural order, both physical and spiritual, and pervades and influences all that we do.

Thus the Regional Land and Water Plan will contain an iwi and pakeha view of integrated natural resource and ecosystem management, which is consistent with, and embraces the best approaches in the world. These deeply held views and proposed approaches in the Land and Water Plan provide a very good framework for consideration of how the Rotorua lakes can be better protected, restored and managed.

While the proposed Land and Water Plan goes into considerable detail on the methods and processes that are proposed to be used, it is important to now set the specific context for protection and restoration of the Rotorua lakes.

3.2 Strategy for the lakes of the Rotorua district - 'Te Kaupapa mo Nga Taonga o Rotorua' (Protecting the Jewels in the Crown of the Lakes of the Rotorua district)

This important document, which was developed and adopted by Environment Bay of Plenty, Rotorua District Council and the Te Arawa Māori Trust Board, sets out a Vision, Goals and Priorities for protection and restoration of the beautiful Rotorua lakes. It was preceded by a public discussion document entitled Towards a Te Arawa Lakes Strategy, which identified a significant range of concerns and interests in the long-term welfare of the lakes. To quote from the Foreword:

"This strategy is not a statutory document under either the Resource Management Act or the Local Government Act or any other Act. Our aim is rather to identify and address the problems arising from a lack of co-ordination between many interests in management of the lakes and then to consider how the law and those concerned can work together to solve those problems effectively and efficiently as possible. We see the Lakes Management Strategy as being an ongoing process with regular review and accountability for achieving key goals that will make a difference and protect the lakes.

We acknowledge that various authorities are carrying out a variety of ongoing activities aimed at protecting the lakes. However, we believe that there is a pressing need to unite efforts and resources to achieve sustainable lake and catchment management, so that this and future generations can continue to use and enjoy the lakes. For the most effective use of community resources, we believe that it is essential to establish and maintain an overview group with a mandate to ensure accountability and action. We seek not only to identify what needs to be done but also to identify the costs involved and that the greatest benefit can be achieved for each dollar spent in meeting these goals."

The vision for the lakes is:

"The lakes of the Rotorua District and their catchments are preserved and protected for the use and enjoyment of present and future generations, while recognising and providing for the traditional relationship of Te Arawa with their ancestral lakes."

Fourteen key goals are set out:

Protection

  1. Address the causes of lake water pollution.
  2. Deal with pollution from septic tanks.
  3. Determine the extent of pollution from stormwater runoff.
  4. Define and refine lake water quality standards.
  5. Examine the status and future of the catchment bank protection scheme.
  6. Address plant and animal pest problems.
  7. Determine present and future reserve areas.

Use

  1. Establish an urban development policy.
  2. Establish a rural development policy.

Enjoyment

  1. Develop a recreation strategy.
  2. Monitor and report on recreation activities.
  3. Define esplanade reserve areas to ensure public access to each lake.

Management goals

  1. Establish in partnership with Te Arawa a co-management framework that achieves the best integrated management.
  2. Establish meaningful and binding working relationships with the iwi/hapu and their ancestral lakes.

The aspects covered in the strategy as set out in the 'parts' are:

  1. Establishing a Community Vision
  2. The Elements of the Vision
  3. Key Goals to Achieve the Vision
  4. Targeting Lake Priorities
  5. Meeting the Costs
  6. Ensuring Accountability
  7. Putting it All Together

Appendix A contains a 'Schedule of Tasks' for each of the 14 key goals. Appendix B provides a summary for each of the lakes covering a description of the lake and its catchment, a vision for the lake and its catchment, issues facing the lake, possible options for addressing the issues, analysis of options and recommended actions. It was useful to review these sections for Lakes Rotorua and Rotoiti in the light of this report.

Overall co-ordination and direction for the strategy is vested in the Lakes Strategy Joint Committee, comprising the Chair of the Te Arawa Māori Trust Board, the Chair of Environment Bay of Plenty and the Mayor of Rotorua District Council plus a further representative from each of the three organisations. This is a key body bringing the three responsible stakeholders and organisations together to ensure all of the work is done cost effectively and to achieve the goals that have been set. Paul Dell of Environment Bay of Plenty has been appointed as the co-ordinator for implementation of the strategy by the three organisations.

The management structure provides for direct involvement of the Māori people at the highest level and this will be important in view of the special relationship that the Te Arawa have with the lands surrounding the lakes and the lakes themselves. It will be especially important in the early identification of sites that will be affected by management measures that are significant for Te Arawa.

3.3 Rotorua Lakes Restoration and Protection Programme

As can be seen from sections 3.1 and 3.2, there is a strong strategic, legal and policy framework in place for protection, restoration and management of the Rotorua lakes. A more detailed programme for all of the supporting information and processes that will be needed is currently being developed and has been well summarised in papers presented by Paul Dell and John McIntosh at the Rotorua Lakes 2003 Symposium held in Rotorua on 9-10 October 2003 (Refs 1 and 2).

These papers summarise the overall approach through the Strategy for the Lakes of the Rotorua District and the Water and Land Plan. As well as the aspects of these two documents summarised above, the following aspects are important.

The strategy identifies seven key projects:

  • water quality
  • catchment and riparian protection
  • reserves and recreation
  • urban and rural growth management
  • water recreation
  • co-management
  • iwi liaison.

The Water and Land Plan sets Trophic Level Index (TLI) targets for each lake. The TLI, which is discussed further below, integrates measures of key nutrients and algal production over a year through averaging of the following measurements:

  • chorophyll a, which is a measure of the density of micro algae or phytoplankton blooms
  • Secchi disc depth, which is a measure of water clarity
  • total phosphorus, which is a measure of the nutrient phosphorus in its various forms that may be available for plant and algae growth
  • total nitrogen, which is a measure of the nutrient nitrogen in its various forms that may be available for plant and algae growth.

The TLI is a useful measure of the trophic status (level of nutrient enrichment and plant growth) for each lake and provides a good target for the community. It is not such a good indicator for overall ecosystem health or to understand the causes of particular events, such as the blue-green algal blooms in Lakes Rotorua and Rotoiti last summer. EBOP clearly understands these distinctions and is taking them into account in the development of lake action plans and implementation of the agreed management options.

In this context, the Rotorua Lakes Restoration and Protection Programme has not been fully documented as it is a 'work in progress'. It is well summarised in Figure 2 on page 15, which is taken from the Dell paper (Ref 1). As can be seen from Figure 2 there are a large number of elements that need to be brought together to implement the Water and Land Plan and the 'Lakes Strategy', including:

  1. reviews of completed research and monitoring to identify information that improves the understanding of processes in the catchments and lakes, that in turn will lead to viable management options
  2. ongoing research and monitoring that is targeted towards understanding key processes and supporting the best management options
  3. action plans for each lake that will set out the best management options for implementation
  4. identification of the funding requirements, including economic analyses to determine the most cost-effective approaches and negotiations to determine the best sources of funding
  5. identification of the works that will be needed to implement the best management options, including the investigations to determine how to best implement them
  6. identification of the 'best management practices' that can be used to reduce or eliminate nutrient inputs from the various land uses and practices in the catchments, and how these can best be implemented in collaboration with landowners and managers
  7. education and communication to keep the community fully informed and appropriately involved at all stages
  8. use of regulations as part of a 'toolbox' of management options to complement and strengthen the management approach when appropriate and needed.

While all of the work that makes up the Rotorua Lakes Restoration and Protection Programme is evolving over time, it would be useful to write the programme up as a document that explains the purpose of each element, how each element builds on and implements the Water and Land Plan and Lakes Strategy, how each element is being done, who is involved and how all of the elements are brought together in the action plans.

Recommendation 1: That the Rotorua Lakes Restoration and Protection Programme is written up as a brief document to explain how all of the elements, from research and monitoring to regulations, are brought together to produce and implement the best management options through lakes action plans.

3.4 Lake action plans

A key step in implementing the Water and Land Plan and Lakes Strategy for the lakes of the Rotorua district is the development in close consultation with all stakeholders, of action plans for each lake where the current TLI exceeds the target TLI. These are typically preceded by 'Draft Working Papers', to set out the issues and options and then a process, including a full SWOT analysis with the community, to identify the preferred management options. The result is the lake action plan, which is then progressively implemented.

Each action plan will:

  • define the existing Catchment Nutrient Budget
  • determine what level of nutrient inputs is sustainable
  • identify agreed nutrient reduction targets
  • determine actions to achieve the agreed targets.

These processes are led by a working party made up of local stakeholders and representatives of relevant organisations. Perhaps the most advanced action plan is that for Lake Okareka where four main management options have been identified:

  1. reticulated sewerage to eliminate nutrient inputs from septic tanks
  2. retirement and revegetation of stream and lake foreshores to reduce nutrient inputs and improve ecosystem health
  3. use of enhanced natural wetlands and artificial wetlands to reduce nutrient and sediment inputs
  4. 'in lake' treatments such as dosing with alum and oxygenation to reduce the internal availability of nutrients and frequency of low oxygen conditions.

These action plans will be an important step involving all of the key stakeholders, including the community, in identifying and then implementing the best management options for each lake.

A single action plan for Lakes Rotorua and Rotoiti is being developed, because of the way they are strongly linked by the Ohau Channel, and should be ready early in 2004.

Figure 2. Rotorua Lakes Restoration and Protection Programme

See this figure at its full size (table text).

 

3.5 Lakes water quality - Environment Bay of Plenty strategic and policy approach

While section 6 provides a fuller summary of the historical monitoring and investigations that have been carried out in Lakes Rotorua and Rotoiti, it is important to first summarise the basis that EBOP uses to set water quality targets. This is well done in EBOP's publication, Rotorua Lakes Water Quality 2002 (Ref 3), which is briefly summarised here.

The introduction of the Executive Summary of the report usefully sets out the basis for EBOP's monitoring, which has been undertaken since 1990, and how this leads to the targets set for each lake. This is reproduced below:

"The Natural Environment Regional Monitoring Network (NERMN) is Environment Bay of Plenty's programme for general 'state of the environment' monitoring. The programme is divided into modules with lake monitoring budgeted as a separate module. Lake monitoring results are reported annually because of their relevance to lake management issues.

The major thrust in reporting the lakes results is calculation of an annual figure for the Trophic Level Index (TLI). This is composed of four interrelated factors that come together and form a sensitive indicator of lake water quality. The four factors are total phosphorus, total nitrogen, Secchi disc depth (clarity) and chlorophyll a (amount of algae).

In the Proposed Regional Water and Land Plan (PRW&LP), the TLI has been used as one method of assessing lake quality in the classification of waters. A baseline quality has been set for each lake at a specific TLI level. A trigger has been proposed using the baseline, so that land management options for reducing nutrient inputs can be evaluated when a lake is definitely deteriorating."

EBOP also considers the Percent Annual Change, which is the average annual rate of change of the Secchi depth, Chorophyll a, total nitrogen, total phosphorus and the oxygen depletion rate (HVOD). Both measures have been used to document changes in all of the lakes as set out in Tables 1 and 2 in Rotorua Lakes Water Quality 2002, which are reproduced as Appendix 1 and 2 in this report. The shaded area in Table 2 in Appendix 2 shows the lakes that are most severely degraded and are priorities for development of action plans.

Table 1 shows the annual average TLI values and Water and Land Plan Targets for Lakes Rotorua and Rotoiti as presented at the Rotorua Lakes 2003 Symposium (Ref 3).

Table 1. Current and management target trophic level indices for Lakes Rotorua and Rotoiti

Lake

TLI in Objective 10

Current TLI (at 2002)

Rotorua

4.2

4.6

Rotoiti

3.5

3.9

As can be seen in Appendices 1 and 2, no overall trend has been detected in the TLI over the reporting periods. But the Rotorua Lakes Water Quality 2002 document also provides graphical summaries of the Secchi disc, Chorophyll a, total nitrogen and total phosphorus concentrations for all of the monthly monitoring from 1990 to 2002. This is valuable data and even a cursory examination shows a number of cause and effect relationships between the four parameters.

Cause and effect relationships, especially between nitrogen, phosphorus and Chlorophyll a, are important because they indicate 'events' that have caused particular algal blooms. An understanding of these events is vital if targeted management measures are to be put in place and this is discussed further in section 6.

EBOP is aware that the TLI measurements are just one way of representing the condition of the lakes and are to be commended on the detailed monitoring it is doing and reporting. Another useful method for characterising the state of the Rotorua lakes has been developed by Professor David Hamilton of Waikato University and this is summarised below.

3.6 Anoxia as a measure of lake health

Professor David Hamilton, who holds the Environment BOP Chair in Lakes Management and Restoration, has analysed all of the available data on the Rotorua lakes (paper in production) and developed four categories based on mixing regimes and dissolved oxygen. Professor Hamilton's work is presented in this section as it is part of EBOP's strategic approach to managing and restoring the lakes, including the creation of the Waikato University Chair to carry out key research to support the development of management options.

The four categories and the lakes that fall into these categories are shown in Table 2.

Professor Hamilton's analysis, as shown in Table 2, clearly shows that Lakes Okaro and Rotoiti are degraded and that conditions in them, especially from late spring through to autumn, are likely to cause algal blooms and stress fish and other aquatic fauna. Lake Rotorua is a shallower lake that is eutrophic and, during periods of stratification, significant amounts of nutrients are released from the sediments and become available for algal blooms. Professor Hamilton is leading other studies that will aid in lakes management and these are discussed further in section 7.

Table 2. Classification of the Rotorua lakes according to their mixing regimes and levels of dissolved oxygen

Rotorua lakes category

Lakes within categories

Lakes that undergo seasonal stratification of temperature and moderate levels of oxygen depletion.

These lakes show trends of reduced levels of oxygen in the bottom waters compared to previous years.

Okareka

Tikitapu

Okataina

Lakes that show a strong seasonal stratification of temperature but where oxygen levels in bottom waters rarely decline below 50% of saturation.

These lakes have remained relatively stable through time, especially with respect to the duration and extent of seasonal decline in oxygen.

Tarawera

Rotoma

Rotomohana

Lakes that are strongly stratified but undergo severe seasonal decline in oxygen to the extent that the entire bottom layer (hypolimnion) is anoxic early in the stratified period.

These lakes are eutrophic and were originally well oxygenated over the full year but have suffered severe declines in oxygen in their bottom waters over the last 30 to 40 years.

Okaro

Rotoiti

Lakes that are shallower that do not stratify seasonally but rather, intermittently, on time scales of a few hours to several days.

These lakes are mesotrophic to eutrophic and the deoxygenation events contribute significant inputs of nitrogen and phosphate to the water column, that over a year are likely to exceed those arising from point and diffuse sources in the catchments.

Rotorua

Rotoehu

Rerewhakaaitu

3.7 Lake quality indicators

While the TLI is a useful indicator for targeting overall lakes water quality, it has limitations and, as identified by EBOP, needs to be supplemented by other measures to present a full picture of the condition of the lakes and hence the priorities for management. Based on Professor Hamilton's recent work and consideration of other factors such as the concentrations of nutrients coming from the catchments and broader ecosystem health, it would be desirable to have additional 'lake quality indicators' to represent the key factors that affect lake quality. Such indicators could include shorter-term concentrations of nutrients in the water column at critical times for algal blooms and the N:P ratio.

Initially, any indicators that are developed should focus on the factors that cause algal problems in the lakes, but consideration should be given in the near future to broader ecosystem indicators.

Recommendation 2: That Environment Bay of Plenty (EBOP) considers developing supplementary lake quality indicators to focus on the factors that cause algal problems in the Rotorua lakes that will complement the Trophic Level Index.


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