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Proposed National Environmental Standard on Ecological Flows and Water Levels: Discussion Document

• Acknowledgements
• Executive Summary
• 1 Introduction
• 2 Ecological Flows and Water Levels in the Context of Environmental Flows and the Resource Management Act
• 3 How Could National Direction Address Issues with Ecological Flows and Water Levels?
• 4 The Options
• 5 Proposal for an NES on Ecological Flows and Water Levels
• 6 Preliminary Evaluation of Costs and Benefits of Preferred Option
• 7 Future Actions to Complement the NES
• 8 What Next?
• 9 References
• Appendix 1: Definitions
• Appendix 2: Existing Approaches to Ecological Flows
• Appendix 3: Environmental Flows and Water Levels
• Appendix 4: Executive Summary and Recommendations from: Draft Guidelines for the Selection of Methods to Determine Ecological Flows and Water Levels (Beca 2008)

2 Ecological Flows and Water Levels in the Context of Environmental Flows and the Resource Management Act

The scope of the proposal set out in this document is limited to ecological flows and water levels. To assess and comment on the proposal and its scope, it is important to understand the wider context of environmental flows and water levels, of which ecological flows are a component. This section of the document describes the resource management framework for environmental flows and water levels by:

• highlighting the importance of environmental flows and water levels to freshwater management

• providing definitions for: environmental flows and water levels; ecological flows and water levels; and available water

• outlining the current process for determining environmental flows and water levels under the Resource Management Act

• describing how environmental flows and levels are implemented

• outlining the technical methods currently used to assess the ecological component of environmental flows and water levels.

While this section concentrates on the wider context of environmental flows and water levels, the proposed national environmental standard addresses some specific issues around the ecological component of environmental flows only. This section is added to assist submitters to understand the boundaries of the proposal.

2.1 Importance of environmental flows and water levels

Water is an integral part of the natural and physical environment. Lakes, rivers, streams, wetlands and aquifers have significant environmental, social and cultural values for New Zealanders. Consumptive uses of water⁵ also provide essential services for the economic and social wellbeing of the country. Water is used for human and stock drinking, firefighting, urban water supply, industry, electricity generation and irrigation.

Environmental flow and water level decisions are made in a context of environmental, social, cultural and economic values. The broad objectives for an effective water allocation system are to develop a decision-making process that makes provision to protect water ecosystems and to provide for existing and future uses of water, while optimising environmental, social, cultural and economic outcomes for the community. Within any water allocation framework, setting environmental flows and water levels is a critical first step.

Environmental flows and water levels provide for a given set of ecological, cultural, recreational and amenity values associated with a particular water body. The flows and levels are established through regional planning processes that determine how much water must stay in a river, lake, wetland or groundwater system, and how much water is available for consumptive uses. Having an environmental flow or water level set ensures that the amount of water needed to sustain a given set of values is clearly specified and the total amount of water available for development uses is also clear, so that decisions can be made about how the available water should be used.

2.2 Defining key concepts

2.2.1 Environmental flows and water levels

The definition of environmental flows and water levels⁶ used in this document is the “the flows and water levels required in a water body to provide for a given set of values which are established through a regional plan or other statutory process”. Environmental flows and water levels may provide for ecological, tangata whenua, cultural, amenity, recreational, landscape, natural character and other values associated with water.

Decisions on the setting of environmental flows and water levels involve consideration of natural, community and development values associated with a water body and how these relate to flow and/or level. Environmental flow decisions determine how much water will stay in a water body, but that decision is influenced by existing and potential demands for water. Decisions are made within the framework of the RMA, national and regional policy statements, and the objectives and policies of relevant regional plans.

Figure 3 illustrates the components of a simplified environmental flow or water level. The values provided for, and the level of protection afforded to each, will depend on the characteristics of an individual water resource and be determined by the outcomes of the decision-making process outlined in the Section 2.3. As shown in the figure, several of the individual values provided for may overlap to a significant degree and it is typically the case that provision for ecological values forms a significant component of the final environmental flow and water level. However, additional flows or higher water levels might be required to provide adequately for these other values.

2.2.2 Ecological flows and water levels

Ecological flows and water levels are a component of the overall environmental flow and water level, and are established to provide for the ecological values attributed to a particular water body. In the context of the proposed standard, ecological flows and water levels are defined as “the flows and water levels required in a water body to provide for the ecological function of the flora and fauna present within that water body and its margins”.

2.2.3 Available water

In order to provide a level of certainty for existing and potential resource users about the amount of water available for allocation, environmental flows and water levels must clearly define the total amount of water available for consumptive uses. This is the amount of water that is not required to maintain the environmental flow or water level defined for a particular water body.

For clarity, this document uses the term available water to mean “the total quantum of water that can be allocated from a resource for consumptive use, including both existing and potential authorised uses”. It includes uses for reasonable stock and domestic water supplies provided by the RMA section 14(3), as well as small-scale abstractions permitted by regional plans.

Because environmental flows and water levels cater for natural variability in water systems, the volume of available water may vary seasonally and possibly between years.

These definitions, and definitions of some other hydrological terms used in this document, are presented in Appendix 1.

2.3 Decisions on environmental flows and water levels

Consultation on the Sustainable Water Programme of Action has highlighted issues with environmental flows and water levels, including how various social, economic and cultural factors are considered and provided for. The proposal set out in this discussion document, because it concentrates on ecological aspects only, does not address those wider issues. However, the following discussion on environmental flows is provided to help submitters understand the context of the proposed national environmental standard and its boundaries.

Decisions on environmental flows and water levels are usually made as part of a regional plan process. Existing approaches to setting environmental flows are contained in proposed and operative regional plans. Eleven out of 16 councils currently have operative regional plans to address freshwater issues, the remainder having proposed plans.

An environmental flow decision incorporates both quantitative and qualitative information on values and on the potential impacts of these values on changing flows and water levels. No matter how comprehensive and robust the information, decision-makers will always be required to make a judgement on the extent to which each value will be provided for and how conflicting values will be addressed. The judgement is made using the framework set out in Part II of the Resource Management Act, national policy statements, regional policy statements and regional plans.

The process of developing a regional plan involves significant consultation and community involvement, with the resulting plan development, submission and hearing processes often taking several years. Regional and national policy statements can also provide guidance on the resolution of environmental flow and water level issues. This consultative process is assisted by a clear decision-making framework and the application of relevant technical methodologies. The overall aim is to determine the most appropriate way of managing a region’s water body for a given set of ecological, cultural, social and economic values associated with alternative uses of the resource.

Environmental flows and water levels have also been set through decisions on resource consents (particularly when a regional plan does not specify environmental flows) or via a water conservation order.

In the setting of environmental flows and water levels, there are three distinct elements:

• a robust scientific methodology for assessing the ‘ecological needs of freshwater ecosystems’ over a range of flow and seasonal conditions

• methods for assessing how other values (including recreational, amenity and tangata whenua values) change over a range of flow and seasonal conditions

• a clear approach to assessing the extent to which an environmental flow or water level will provide for natural and development values attributed to a water body by Māori and the wider community.

The proposals outlined in this discussion document concentrate on ecological flows and water levels and, therefore, on only the first element listed above.

Appendix 2 contains an overview of the technical part of the approaches to environmental flows currently adopted by each regional council. Appendix 3 contains a fuller explanation of environmental flow decisions.

It is important to note that in some cases where the in-stream values are very high and/or the community wishes to see a higher level of protection for a water body, there may be no, or very little, consumptive use and the majority of the flow may be protected in its natural state.

2.4 Implementation of environmental flows and water levels

Environmental flows and water levels are implemented by rules in regional plans and resource consent conditions that place controls on the taking, damming, diversion and use of water. These decisions are guided by regional policy statements, regional plans and water conservation orders. Guidance could also be provided by a national policy statement.

Environmental flows and water levels must take account of the natural variability in water systems. As a result, a combination of numbers may be required to provide for the values associated with an individual water body rather than a single number. In some applications, the term ‘environmental flow or level regimes’ is used to better indicate that environmental flows and water levels need to reflect and respond to the natural variability in water systems.

The range of measures required to implement the environmental flows and water levels will depend on physical characteristics of the water resource, the nature and magnitude of water demand and, most importantly, the significance of the values of the water body and its connected environments (eg, groundwater and downstream ecosystems).

The complexity of environmental flows and water levels should match both existing knowledge of the physical characteristics of the resource as well as the availability of relevant, on-going monitoring information. For example, there is little to gain from setting a complex environmental flow and water level in a river system with little or no flow- or water-use monitoring. In systems where there is a possibility of storage and likely capacity to take water at high river flows, or there is potential for off- or on-stream storage, a more complex regime is warranted.

Environmental flows for rivers and streams are usually described with a combination of measures such as minimum flows,⁷ allocation caps, flow sharing⁸ and limits on abstraction during higher flows and floods. Environmental flows usually include two parts – a threshold or minimum flow and a cap or limit (an allocation limit) set on the amount of water that can be taken. The allocation limit can vary with time and flow. The allocation limit provides for the ecological and habitat components that are related to flow variability and maintaining a range of flows in a river or stream. The allocation limit is linked to the minimum flow – as the allocation limit increases, the minimum flow is reached more often.

As the level of allocation from a river increases, environmental flows and water levels usually become more complex. Complex environmental flows for rivers can include provision for low flows, channel-forming / maintenance flows, wetland inundation flows, flushing flows for removal of vegetation or fine sediments, and groundwater recharge flows.

Groundwater environmental flows and water levels can be set as limits to the amount of water that can be taken, and provide a means of maintaining spring flow, aquifer pressure and recharge flows to rivers or wetlands. Groundwater trigger water levels (or pressures) are also used for preventing salt-water intrusion or adverse pressure gradients.

For lakes and wetlands, environmental flows and water levels usually specify permitted ranges in water levels and rates of fluctuation. Water level fluctuations are particularly critical for ecological values and they control the distribution of organisms in most wetlands and the littoral zone in lakes. The timing and duration of the connectivity of wetlands to their parent water-body controls the migration of fish and feeding cycles of birds.

Environmental flows or water levels, although possibly developed following a generic methodology, will be specific to an individual water body.

2.4.1 Resource consents and environmental flows and water levels

Regional plans also adopt a variety of approaches to deal with resource consent applications that would, if granted, lead to established environmental flows and/or water levels being exceeded (or breached). While some regions classify such applications as being for discretionary activities, others deem them to be for non-complying activities. This difference in activity status can make a significant difference to the potential outcomes of the resource consent process and the resulting effectiveness of environmental flows and water levels developed through the regional plan process.

In practice, applicants have been successful in applying for a water permit even where the permit would breach allocation limits set in a plan and even where further abstraction is a non-complying activity.

2.5 Examples of environmental flows applied to a river

Figures 4 and 5 illustrate environmental flows applied to river flow. The figures illustrate how specifying the environmental flow also determines the available water. The same concept applies to groundwater, lakes and wetlands, where the variable may be water levels or flow and the timescales, particularly for groundwater, may be years rather than days. The illustrations could apply to each component of environmental flows or water levels – flows could be those that provide for ecological, recreational, cultural and other values. The discussion below, therefore, relates to both ecological flows and the wider concept of environmental flows.

Figure 4 illustrates a very simple environmental flow which is defined by:

• a minimum flow specifying when abstraction must cease or be reduced

• a single allocation limit specifying the quantum of available water, which is over time except when it must be reduced to ensure that the minimum flow is not breached.

The example given in Figure 4 does not illustrate one common feature of many environmental flows and water levels – that some water will be taken even when a river is below its minimum flow. Water taken under section 14(3)b or 14(3)e of the RMA (ie, water taken for human and stock drinking and firefighting). This is often exempt from minimum flow restrictions, because this type of abstraction is a permitted activity in a plan and some resource consents (these usually specify water for community supplies of human and stock drinking). Guidance on exemptions is usually contained in regional plans.

In Figure 5, a further measure (flow sharing) is introduced at higher flows – this approach enables more water (compared to Figure 4) to be taken when river flows are high. The smaller box to the right shows the same arrangement but with all the environmental flow components plotted together. The effect of flow sharing on maintaining flow variability is evident. Flow sharing is not the only, nor necessarily the best, way to provide flow variability and has been included as one example of a commonly used approach.

2.6 Technical methodologies used for setting ecological flows and water levels

Regional councils use a variety of approaches for establishing ecological flows and water levels. Approaches range from a detailed modelling-based assessment of the potential impacts of water use scenarios, to simpler approaches based on historical data. Environmental flows and water levels may also be applied at a range of scales, from generic (default) regional approaches to water body-specific management plans.

At the current time, there are no specific guidelines on which technical methods to use, and how, for establishing environmental flows and water levels through the resource consent or regional plan processes. The 1998 Ministry for the Environment publication Flow guidelines for instream values lists several methods for the determination of environmental flows and water levels for surface water bodies, but does not prescribe their application to any particular physical setting. As a result, individual regional councils determine ecological flows and water levels in a manner suited to both the physical characteristics of individual water resources and their communities.

The key methods for establishing ecological flows and water levels implemented by councils are default hydrological methods (eg, based on a proportion of the mean annual (seven-day) low flow, or MALF) and instream habitat methods (ie, the Instream Flow Incremental Method IFIM or WAIORA⁹). Modelling methods have generally been used on larger rivers and streams because these water bodies have more information available on water flows and values. Councils have noted the difficulty of determining ecological and environmental flows where there are minimal data (on water flows and ecological values), especially in areas with many smaller streams.

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