Part 4: Freshwater quality monitoring

Managing Freshwater quality: Challenges and opportunities.

In this Part, we discuss:

Summary of findings

Each of the four regional councils have robust freshwater monitoring programmes. Some councils have a better understanding of freshwater quality in their regions than others. The four regional councils could make changes to produce a more representative picture of the state of freshwater in their regions.

The four regional councils were at various stages of incorporating mātauranga Māori into their monitoring programmes. This includes integrating cultural monitoring indicators into freshwater quality monitoring programmes.

Monitoring freshwater quality

Monitoring long-term trends in freshwater quality allows regional councils to understand what is happening to freshwater quality in different sites.

Monitoring freshwater quality supports a range of regional council activities. These include:

  • reporting on the state of environment;
  • monitoring the effectiveness of regional plans;
  • monitoring compliance with resource consents and regional rules on resource use;
  • informing resource consent processes; and
  • helping determine nutrient thresholds to manage the effects on ecological health.

Collecting good information and using it well is essential to making well-informed, evidence-based policy decisions.

Regular monitoring is also needed to effectively implement the National Policy Statement. As discussed in Part 2, the National Policy Statement directs regional councils to set objectives for the state of freshwater in their regions and to set limits on resource use to meet these objectives. Knowledge of states and trends is necessary to appropriately manage freshwater quality (for freshwater quality to be maintained or improved). Figure 4 describes what regional councils measure and report on.

Figure 4
What regional councils measure and report on

The most common variables that regional councils and NIWA measure and report on include:

Bacteria – Faecal coliforms, E. coli, and enterococci indicate the presence of human or animal faeces and the associated risk of infectious disease for people swimming in or drinking the water, and for livestock from drinking the water.

Nutrients – Increased levels of various forms of nitrogen and phosphorus in water bodies can cause excessive plant growth rates, which can lead to blooms of algae and nuisance weeds. These can then reduce the recreational and aesthetic value of water bodies and affect fish and other aquatic animals.

Visual clarity – A river or lake with low clarity can indicate significant erosion in the catchment or algal growth in the water. Low clarity affects fish feeding and spawning habits, plants' growth rates, and recreational uses.

Macroinvertebrate Community Index (MCI) – This measures the composition of the invertebrate animals that live on the river beds. The MCI gives an overall indication of river health and water quality.

Periphyton – The algae that grow on the beds of rivers, streams, and lakes turn dissolved nutrients into nutritious food (periphyton biomass) for invertebrates, which are themselves food for fish and birds. Elevated levels of nutrients can cause periphyton blooms – long filamentous growths or thick mats that cover much of the streambed. Too much algal growth can be a nuisance for swimming, fishing, and kayaking and can adversely affect fish and insect life in rivers.

Analysis of monitoring networks

In 2011, we commissioned NIWA to provide an independent expert view of the four regional councils' freshwater quality networks. NIWA found that the four regional councils had "well-planned and operated networks for assessing the current state and long-term trends in physical and chemical quality of rivers, lakes, and groundwater".

In particular, "the distribution of sampling sites across each region was deemed representative", and the four regional councils were monitoring an appropriate range of variables, employed adequate quality assurance and quality control processes, and followed acceptable data storage procedures.

We asked NIWA to assess of the effectiveness of the freshwater quality monitoring networks and approaches so we could provide a view of how fit for purpose they are.

NIWA's analysis took into account substantial changes to freshwater quality management regulation and laws since 2011. The National Policy Statement for Freshwater Management is the most significant change. It establishes national objectives to be met for multiple freshwater attributes including physical, chemical, and biological properties of rivers and lakes. These attributes are to be managed to ensure that regional water quality is maintained or improved within freshwater management units.

The Australian and New Zealand Environment Conservation Council updated its guidelines for fresh and marine water quality in 2018. The revised guidelines provide default values for finer spatial-scale ecoregions compared to the previous guidelines.

Monitoring networks overall

NIWA found that the four regional councils each have robust freshwater monitoring programmes that regularly sample a common subset of physio-chemical, microbiological, and biological variables in rivers, lakes, and groundwater. NIWA also suggested ways in which the four regional councils could improve the representativeness and "statistical power" of their networks.

River monitoring

The four regional councils monitor the attributes for river ecosystem and human health identified in the National Policy Statement. The four regional councils also sample most of the core variables recommended by the National Environmental Monitoring and Reporting working group for river monitoring.26

The four regional councils have also begun adapting their practices to new regulations. For example, Environment Southland and Taranaki Regional Council have introduced monthly periphyton sampling programmes to meet the new requirements under the National Policy Statement.27 Waikato and Horizons Regional Councils have introduced more sites for monitoring recreational bathing. This reflects the increasing focus on freshwater swimmability.

Lake monitoring

The four regional councils measure all the lake attributes identified in the National Policy Statement, except for planktonic cyanobacteria.28 Waikato Regional Council measured planktonic cyanobacteria in some of its lakes. Environment Southland has provided information showing that it has consistently monitored cyanobacteria at its lake-monitoring sites over the last two years. Taranaki Regional Council provided information showing that it monitors all of the lake attributes identified in the National Policy Statement and consistently measures all variables at each monitoring site.

Groundwater monitoring

The four regional councils sample a common subset of groundwater variables. NIWA advised that groundwater monitoring is currently spread across several different programmes within each region. It recommended combining the various programmes into one network (with the same set of variables at all sites) to improve consistency and enable power analyses to be conducted.29

Water quality sampling, analysis, and data storage

Each of the four regional councils follow established sample collection and analytical procedures for the majority of water quality variables measured in river, lake, and groundwaters. All data are stored in accessible database formats. However, there was some variance in methods.


All four regions have an over-representation of river monitoring networks in lowland and pastoral areas. It also found an under-representation of monitoring networks in upland sites (sites dominated by natural land cover, particularly indigenous forest).

NIWA suggested that the four regional councils could improve the representativeness of their monitoring networks by adding specific river-based monitoring sites to their networks.

Statistical power

Statistical power refers to the likelihood that a study will detect an effect when there is an effect to be detected. One of the factors affecting power analyses is the size of the sample being considered. In short, large samples offer greater test sensitivity than small samples.

NIWA assessed the statistical power of regional river monitoring networks as the ability to distinguish mean values of water quality variables within each class from relevant guideline values. It noted that, in many cases, there are less than two sites in a given class, which prevents power analysis from being conducted. It suggested that a useful first step to address this would be to add at least one or two sites in these classes to enable future analysis.

Recommendation 2

We recommend that Waikato Regional Council, Taranaki Regional Council, Horizons Regional Council, and Environment Southland consider how they might use the analysis conducted by National Institute of Water and Atmospheric Research Limited to improve their monitoring of freshwater quality.

Mātauranga Māori and citizen science in freshwater monitoring

We looked at how effectively the four regional councils incorporated mātauranga Māori and citizen science initiatives into their monitoring programmes. The 2017 amendments to the National Policy Statement require every regional council to prepare a monitoring plan that includes methods for monitoring whether the values identified under its policy requirements are being provided for. This includes mātauranga Māori values.

Mātauranga Māori can been defined as "the knowledge, comprehension, or understanding of everything visible and invisible existing in the universe" and is often used synonymously with wisdom.30 Mātauranga Māori is an important part of freshwater quality management because it values the perspectives of Treaty partners and can lead to insights into the health of the ecosystem as a whole.

The most common way regional councils implemented mātauranga Māori in their monitoring programmes was by including cultural health monitoring indicators. These indicators can include water clarity and flow, the form of the riverbank, the presence of certain fish, insect and bird species, or the smell of the water.

At the time we visited them, the four regional councils had made variable progress in incorporating mātauranga Māori into their monitoring programmes. Councils were supportive and had taken the first steps towards implementing cultural health monitoring indicators or were actively looking at how to make those first steps.

Since we visited the councils, Waikato Regional Council has advanced a programme to incorporate mātauranga Māori perspectives into all the work the Council carries out. The desired outcome is that incorporating mātauranga Māori perspectives becomes the business-as-usual approach.

One of the potential benefits of the programme will be improvements to the Council's ability to align the Waikato Regional Policy Statement, the Waikato Regional Plan, the Vision and Strategy for the Waikato River, the National Policy Statement for Freshwater Management, and iwi environmental/management plans with mātauranga Māori. Implementing this programme is under way and scheduled to be completed by the end of 2020/21.

People in the wider community can also carry out freshwater monitoring. This is called citizen science and is more widely supported and advanced in the four regional councils than it was in 2011. Some councils have been providing stream health monitoring and assessment kits prepared by NIWA to iwi and community groups so that they can test freshwater quality.

We encourage the four regional councils to continue working closely with iwi and hapū to implement and use mātauranga Māori monitoring in their monitoring programmes.

26: Taranaki and Horizons Regional Councils are the only two to measure total suspended solids and river flow.

27: NIWA concluded that Horizons Regional Council had introduced monthly periphyton sampling to meet the requirements of the National Policy Statement. Horizons Regional Council staff advised us that monthly periphyton sampling began in 2007.

28: Cyanobacteria (commonly known as blue-green algae) are potentially toxic and can multiply and form blooms in rivers or lakes (where they are known as planktonic cyanobacteria). For more information, see

29: For a short description of power analysis, see paragraphs 4.21 and 4.22.

30: For more information, see