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Appendix 3: Environmental Flows and Water Levels

The process of setting environmental flows and water levels

The process of setting environmental flows and water levels is undertaken by regional councils under the Resource Management Act (RMA). This process requires community participation and allows stakeholders to make submissions on the form and content of proposed provisions. The process also provides a right of appeal to the Environment Court against decisions made by council.

The setting of environmental flows or water levels requires a judgment to be made by a regional council on the management interventions required to provide for the values attributed to a water body, taking into account both natural and development values. This judgement is made in accordance with the priorities set in Part II of the RMA, national policy statements, regional policy statements and regional plans, and is informed by technical and subjective assessment of the likely consequences of changes to water flows or water levels to the values attributed to the water body.

Regional plans adopt a wide range of approaches to setting environmental flows and water levels for surface and groundwater resources. Approaches vary significantly in terms of the technical assessment methods used and may be applied at scales ranging from catchment-specific plans to more generic (or default) regional approaches. Regional plans also differ significantly between individual regions with regard to the specific provisions relating to the management of lakes, wetlands and hydraulically connected groundwater.

The role of science

Science plays an important role in the process of setting environmental flows and water levels. Science has a particular application in characterising the physical attributes of a water body and providing assessments of how changing flows or water levels may impact on these features. However, not all attributes of a water body can be readily assessed in quantifiable terms, particularly those more subjective values.

Determination of an appropriate environmental flow or level, therefore, has to incorporate both quantitative and qualitative information on the potential impacts of changes to flows or water levels on values associated with the water body. Science can help provide information on the relationships between flows and values. However, the decision-making process also requires a judgement to be made on the extent to which individual values are provided for in the final environmental flows or water levels adopted, especially where there may be conflict between these values.

It is important that the quantifiable and measurable parameters of a water body are clearly presented, separately from more subjective measures, so that all interested parties and decision-makers can see and understand what the final flow limits have been based on.

Dealing with uncertainty

One of the major challenges facing councils in determining appropriate environmental flows and water levels is dealing with the uncertainties inherent in many of the data used to inform the decision-making process. This uncertainty results from a combination of the variability inherent in natural hydrological systems, scientific error in technical assessment methodologies, and the subjective nature of the assessments required to quantify potential impacts of altering the flows and/or water levels on values associated with a particular water body (eg, impacts on landscape, amenity and cultural values).

Methods for dealing with uncertainty include:

  • clearly identifying uncertainties in information and methodologies used in the decision-making process and recording how these were considered in that process

  • adopting an approach to setting environmental flows and water levels that reflects uncertainty and potential cumulative effects where limited information is available to describe the physical characteristics of the resource

  • developing a flexible management approach whereby the volume of available water changes as more information becomes available

  • providing an adaptive mechanism that allows for environmental monitoring information (including impacts on associated natural values) to be incorporated into a review of environmental flows and water levels.

Determination of appropriate environmental flows and water levels also has to take into consideration future uncertainty associated with the potential impacts of both climate variability and climate change. Both factors should be taken into account, particularly where information on historical flows and water levels is used to inform the decision-making process.

The catchment context

Environmental flows cannot be set without consideration of the management of the surrounding existing and future catchment. If a catchment is intact and has high water quality, then the in-stream environment is more robust and the amount of water taken can have a lesser effect than in a very modified catchment. Mitigation in the form of catchment land-use changes (eg, provision of tall shading riparian vegetation and other improvements to water quality) can make a water body more robust to changes in flow, and when calculating the environmental flow, it may be possible to take more water. When setting environmental flows it is, therefore, best practice to integrate decisions with land-use and water quality management so that all potential effects of future use can be considered holistically.

Challenges in practice

Consultation with regional councils undertaken as part of the Sustainable Water Programme of Action identified a number of challenges in the development and timely inclusion of environmental flows and water levels in regional plans. These include:

  • some decision processes have become very litigious, resulting in long timeframes to collect and analyse robust and defensible data, consult with polarised stakeholders and go through contentious hearing and Environment Court processes

  • limitations on financial resources as well as the availability of appropriate technical skills and experience

  • a lack of defendable scientific data and other information that often requires years of collection to be statistically valid. Even what is considered good science and adequate data may still be contested by stakeholder experts in hearings and court

  • outcomes of resource consent and environment court processes that deliver outcomes not entirely consistent with policies and objectives in regional plans

  • a historical focus on minimum flows rather than environmental flows, which means that some existing plans provide limited guidance about how to address environmental flows when demand for water is high. This results in limited protection for instream values if demand should increase, and a lack of assurance that key ecosystem function is safeguarded

  • the lack of consistent methods for responding to the potential impacts of future climate variability or climate change on the availability of water resources

  • the lack of flexibility in existing planning instruments that prevent implementation of adaptive approaches. Such approaches would enable environmental flows and water levels to be adjusted over time as knowledge increases.

A particular issue for practitioners is the need to clearly distinguish the technical tools used to generate and assess options from the fundamental resource management decisions required. A great deal of time can be spent arguing about an appropriate method for setting environmental flows, because flows cannot be ‘standardised’ in the same way that a water quality standard can. The water quality requirements for trout can be described relative to a specified and measurable level of contaminant, but trout requirements cannot be related to a given flow applicable in all rivers. The national environmental standard aims to reduce significantly the need for technical debate to be repeated countless times in separate plan and/or consent decisions. However, this debate should not be confused with two, more important resource management questions, which are: What environmental values should be sustained? and: What level of protection is appropriate, given all the interest in a water body?

Another issue is the need for a more flexible, responsive system for water allocation. In particular, the development of many water resources in recent years has proceeded at a faster rate than corresponding rules and policies can be developed through the regional plan process. As a result, some water resources do not have adequate environmental flows and/or water levels in place, resulting in resource consent decisions being made on an ad hoc basis rather than at a catchment scale.

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