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4. How Does the National Environmental Standard Apply to Water and Discharge Consents?

4.1 Introduction

Regulations 6, 7 and 8 of the NES apply to applications for water and discharge permits issued by regional councils. The provisions apply only to activities that may affect the quality of a registered drinking water supply providing 501 people or more with drinking water for 60 or more calendar days in a year.

It is important to bear in mind that these regulations should not place a large burden on most consent applicants. Normally an applicant would be required to prepare an assessment of environmental effects for a water or discharge permit. At present these reports may include assessments of effects on the water quality of aquatic ecosystems, recreation or livestock drinking water. What the NES does is explicitly state that the effects on drinking water sources must also be considered in this assessment.

In many instances, particularly for surface water, the requirements for the effects of an activity on aquatic ecosystems, recreational uses or other uses are likely to be more stringent than those for drinking water. Therefore, it is unlikely that many activities will adversely affect the quality of a drinking water source while meeting all other requirements of a regional plan (especially for surface waters). As a result, adding consideration of effects on drinking water should not be a major additional requirement.

As with any other potential effect, the onus is on the applicant to provide an assessment of the effects of their proposal on drinking water sources. If applications for consents do not contain the information needed to make such an assessment, then the application should not be accepted or a further information request should be made (under section 92 of the RMA).

These regulations are relevant for both water and discharge permits. Water permits include all activities listed in section 14 of the RMA (ie, water take, use, damming and diversion).

4.2 Registered drinking water supplies

The NES only applies to sources from which water is abstracted for use in registered drinking water supplies. These supplies are those recorded in the drinking water register maintained by the Ministry of Health. A registered drinking water supply is defined in the NES as “a drinking-water supply that is recorded in the drinking-water register maintained by the chief executive of the Ministry of Health (the Director-General) under section 69J of the Health Act 1956”.

4.3 Treatment status

A consent applicant must consider the status of a drinking water treatment process at the time the application is lodged. Specifically, this means considering both the quality of water from the drinking water supply, in terms of compliance with the DWSNZ, and the type of treatment process in place at the time of the consent application.

Regulation 3 of the NES states that existing treatment:

means the treatment process in respect of a registered drinking-water supply at the time an application for resource consent is made or a proposal to include or amend a rule in a regional plan is notified, as the case may be.

This precautionary approach is used to ensure public safety, because planned treatment upgrades may not occur before consent is given effect to, or, in a worst-case scenario, may not happen at all.

4.4 Effects of the national environmental standard on plan rules and resource consents

The NES applies equally to all consent applications, whether they are for a controlled, a restricted discretionary, or a non-complying activity. This is because a rule or resource consent cannot be more lenient than a national environmental standard under section 43B(3) of
the RMA.

The NES is a regulation, so it is binding and prevails over rules and resource consents. Plan rules and consents operate only to the extent that they are consistent with the NES (section 43B). A consent authority cannot grant a consent contrary to any regulations (section 104(3)(c)(iii)). In other words, if an application for a controlled activity is considered not to comply with the NES, then the application cannot be granted even though the activity has controlled status in the regional plan (section 104 (3)(c)(iii)).

4.5 Steps to consider when processing a consent under the national environmental standard

Figure 4 gives a basic overview of the general steps to follow to assess the potential effects of an activity on drinking water quality.

Figure 4: Basic overview of suggested steps to follow when considering a water or discharge consent under the National Environmental Standard for Sources of Human Drinking Water

This flowchart shows a summary of steps to follow when considering a water or discharge consent under the NES for Human Drinking water.

Step 1 – Identify contaminants in the discharge that are determinands (or precursors)
Step 2 – Identify location of abstraction point(s)
Step 3 – Identify treatment plant location and check compliance of drinking water
Step 4 – Assess concentration of determinands at abstraction point
Step 5 – Assess concentration of determinands after treatment

Compare steps 4 and 5 against the effects thresholds in Reg.7 and Reg. 8(2)(b)

Figure 5 on the following page gives a step-by-step description of making a decision on a resource consent under the NES. On pages 21 – 27 is a more detailed explanation of each step, which should be read in conjunction with Figure 5.

Figure 5: Flow diagram for considering water take and discharge permits under the National Environmental Standard for Sources of Human Drinking Water

This flow chart summarises the steps to follow when considering water take and discharge permits under the NES for Sources of Human Drinking Water. A detailed description of each step can be found in the text following the figure on pages 21 to 27.

Notes:

1 DWSNZ – Drinking Water Standards for New Zealand 2005.

2 Aesthetic determinands must not exceed guideline values in drinking water after existing treatment.

3 This assessment needs to take into consideration the possible dilution, inactivation or degradation that will occur between the activity and the abstraction point.

4 Determinand includes aesthetic determinands.

5 This relates only to granting or declining consents in terms of compliance with the national environmental standard. This does not include consideration of any other aspects requiring consent.

4.5.1 Step 1: Does the NES apply?

The first question a resource consent officer should ask to determine whether or not the NES applies to a resource consent application is: What type of resource consent is being applied for? The NES applies to water and discharge permits only. If the application is for any other kind of permit, Regulations 6, 7 and 8 do not apply (although Regulations 11 and 12 may, as discussed in chapter 6).

[6] Type of activity to which regulations 7 and 8 apply

Regulations 7 and 8 only apply to an activity that has the potential to affect a registered drinking-water supply that provides no fewer than 501 people with drinking water for not less than 60 days each calendar year.

The NES applies to discharge permits because they are likely to result in the discharge of contaminants into water. It may be less obvious why this regulation applies to water permits for takes, uses, damming and diversions. The reason is that these consents can affect river volume and flow, which in turn can affect the dilution of determinands, the settlement of sediment and the growth of algal blooms.

Example: discharge consent

A meat-processing plant is applying for consent upstream from the abstraction point of a water treatment plant. The proposed plant requires a consent to discharge contaminated water into the river. The discharge will include several determinands, including E. coli (which indicates the potential presence of other microbes that can cause disease).

If the increase in the amount of E. coli can not be treated by the existing water treatment processes, this could result in the drinking water not meeting the health quality criteria of the DWSNZ and ultimately causing consumers to become ill.

The effects of the proposal on drinking water quality therefore need to be considered when processing this consent. If the assessment shows that the increase in E. coli can be satisfactorily treated by the existing treatment process, so that drinking water still meets health quality criteria and is safe to drink, then consent can be granted. If, however, the assessment shows that the increased concentration of E. coli cannot be satisfactorily treated by the existing process, the consent can not be granted. Modification of the proposed activity will be needed before consent can be granted (eg, additional treatment of meat-processing waste before discharge).

Example: water take or diversion

A factory located upstream from the abstraction point of a water treatment plant discharges nutrients. A consent application is made to take water from the river inbetween the factory and abstraction point. This activity could decrease the flow of the river, which could lead to decreased dilution of nutrients, an increase in the travel time for nutrients and/or increased water temperature. Dilution of nutrients, and/or warmer water, can produce an algal bloom, which could flow downstream to the abstraction point for the drinking water plant.

Algal blooms can produce toxins that cause health effects, and can also affect the aesthetic properties of the water. Thus, an algal bloom could affect both the safety and aesthetic properties of finished drinking water. The effects on drinking water therefore need to be considered and minimised before the consent can be approved.

4.5.2 Step 2: Is the application for an activity located upstream of a drinking water source?

The second question to ask is whether or not the application is for an activity that would be likely to affect a registered drinking water supply that provides 501 or more people with drinking water for at least 60 days each year. To determine this, the council officer needs to know the location of drinking water sources in the region. A database including information on the location of these sources is kept by the Ministry of Health for all of New Zealand. The Ministry for the Environment makes a version of this database, which is modified for use by council officers. The database has been developed to be compatible with Geographical Information Systems (GIS), so the data could be shown as another layer in the council’s GIS. This database is available to appropriate regional council staff upon request.8 More detail is provided in Appendix 2 of this report.

Individuals outside local government should contact a drinking water assessor at their local public health unit if they require information about the location of a drinking water source or the quality of drinking water from a particular supply. Some public information on individual drinking water supplies is also available at the website http://www.drinkingwater.org.nz/

4.5.3 Step 3: Will the activity produce any determinands?

At this point the question that needs to be asked is: Will the activity discharge, or lead to the formation of, contaminants that can adversely affect human health or the aesthetic properties of drinking water?

The NES does not apply to all contaminants,9 only to a group of substances that can adversely affect human health or the aesthetic properties of drinking water. Specifically, it applies to specific substances identified in the DWSNZ. The NES uses the term ‘determinand’ instead of ‘contaminant’ to refer to these substances. ‘Determinand’ has a specific meaning, which is narrower than that of ‘contaminant’ (as defined in the RMA). It refers only to substances listed in the DWSNZ.10

The NES is intended to apply only if the activity will:

  • discharge contaminants that have human health effects if present in drinking water

  • discharge contaminants that could lead to the formation of determinands that could affect human health. This includes activities that alter the properties of water in a way that could increase the concentration of contaminants or lead to their formation (eg, discharge of warm water could increase the risk of algal blooms, which can produce harmful toxins)

  • affect a water body in a way that could lead to increased concentrations of contaminants (eg, diversion of water could lead to reduced volumes and thus reduced capacity for dilution of contaminants; damming of water could decrease the flow and/or increase the retention time, thus increasing the potential for algal blooms)

  • generate contaminants that could reduce the effectiveness of drinking water treatment processes (eg, sediment)

  • adversely affect the aesthetic properties of the drinking water (eg, taste, smell, appearance).

The DWSNZ specify two main kinds of determinand that can adversely affect human health microbiological (eg, bacteria, viruses) and chemical (eg, arsenic, nitrate). The DWSNZ specify maximum acceptable values (MAVs) for these determinands. Concentrations of determinands above these levels could adversely affect human health. Under the NES, consent cannot be granted if an activity is likely to result in concentrations of a determinand above the MAV in treated drinking water.

Appendix 1 contains more information on determinands regulated by the NES. Appendix 4 lists the types of determinands produced by different activities.

4.5.4 Step 4: Does the application include adequate information to assess its effect on drinking water?

The next issue to consider is whether the applicant has provided sufficient information for the consent officer to determine the effects of the proposal on drinking water sources. The onus is on the applicant to provide this information for a full assessment of effects. If the application does not include the information required, then further information can be requested under section 92 of the RMA.

4.5.5 Step 5: Is the drinking water tested in accordance with the compliance monitoring requirements in the DWSNZ?

The next consideration is whether the drinking water supply that is potentially affected by the proposed activity currently complies with health quality criteria. ‘Health quality criteria’ is a shorthand phrase for water that is safe to drink in accordance with the monitoring and regulatory requirements of the Ministry of Health. Definitions of ‘meet the health quality criteria’ and ‘does not meet the health quality criteria’ are given in Regulations 4 and 5 of the Standard, which state:

[4] Meaning of ‘meets the health quality criteria’

(1) In these regulations, in relation to drinking water, meets the health quality criteria means drinking water that –

(a) is tested for determinands –

(i) at the point where the drinking water leaves the treatment process concerned but has not yet entered the distribution system concerned; or

(ii) at some point in the distribution system, if any particular determinand is not tested at the point referred to in subparagraph (i); and

(b) is tested in accordance with the compliance monitoring requirements in the Drinking-water Standard; and

(c) when analysed, does not contain or exhibit 1 or more determinands exceeding their maximum acceptable values for more than the allowable number of times as set out in Table A1.3 in Appendix 1 of the Drinking-water Standard.

(2) For the purposes of subclause (1)(c), the most recent complete annual results for the drinking water contained in the Water Information New Zealand database maintained on behalf of the Ministry of Health must be used.

[5] Meaning of does not meet the health quality criteria

(1) In these regulations, in relation to drinking water, does not meet the health quality criteria means drinking water that –

(a) is tested for determinands –

(i) at the point where the drinking water leaves the treatment process concerned but has not yet entered the distribution system concerned; or

(ii) at some point in the distribution system, if any particular determinand is not tested at the point referred to in subparagraph (i); and

(b) is tested in accordance with the compliance monitoring requirements in the Drinking-water Standard; and

(c) when analysed, contains or exhibits 1 or more determinands exceeding their maximum acceptable values for more than the allowable number of times as set out in Table A1.3 in Appendix 1 of the Drinking-water Standard.

(2) For the purposes of subclause (1)(c), the most recent complete annual results for the drinking water contained in the Water Information New Zealand database maintained on behalf of the Ministry of Health must be used.

This part of the regulation and some parts of the definitions (Interpretation: Regulation 3) have the purpose of defining what type of water is safe to drink. It is important to note that this does not mean regional councils now need to be in the business of defining whether water is safe to drink. Nor do they need to become experts in drinking water quality. This role will continue to be filled by water suppliers, drinking water assessors and contractors to the Ministry of Health. The purpose of Regulations 4 and 5 is simply to clarify the situations in which later parts of the NES apply.

Both Regulations 4 and 5 of the NES refer to water that has been “tested in accordance with the compliance monitoring requirements in the DWSNZ”. Therefore, these definitions do not apply to water that has not been tested or monitored to these requirements. Figure 5 gives a summary of situations in which the regulations apply.

The testing requirements outlined in the Ministry of Health’s DWSNZ require that drinking water supplies are not only monitored, but that monitoring is carried out correctly, including taking a sufficient number of samples for statistical validity and using acceptable sampling and analytical methods. If monitoring is not carried out correctly, it is not possible to have confidence in the results and the quality of water from the supply cannot be known for certain.

Therefore, there are three different situations in which a water treatment facility could fall under Regulation 8:

  • the water has not been tested at all (section 8[1])

  • the water has been tested, but not in a way that complies with the DWSNZ requirements (section 8[1])

  • the water has been tested and does not meet health quality criteria (section 8[2]).

4.5.6 Step 6: Does the drinking water meet the health quality criteria?

The next question is whether the drinking water meets or does not meet health quality criteria. These criteria are not met when monitoring shows that the water contains determinands that exceed the maximum acceptable values (MAVs) specified for the health-based criteria more often than is allowed for by the DWSNZ. The MAVs for determinands are specified in the DWSNZ. For more detail on these standards, please consult the two ESR technical reports A Guide to the Ministry of Health Drinking-water Standards for New Zealand and An Introduction to Drinking Water Contaminants, Treatment and Management. These guides are available here

The DWSNZ also specify the number of allowable MAV exceedances. This number increases in line with the number of samples taken. Basically, the greater the number of samples taken, the greater the number of exceedances allowed.

Appendix 5 lists the number of exceedances that can be tolerated for 95 per cent confidence that a benchmark is not being exceeded more than 5 per cent of the time. Table 3 is taken from Appendix 5 to give an example of the number of exceedances allowed compared to the number of samples taken.

Table 3: Allowable exceedances (for 95% confidence that the maximum acceptable value is exceeded no more than 5% of the time)

Number of allowable exceedances Number of samples
0 38–76
1 77–108
2 109–138
3 139–166
4 167–193
5 194–220
6 221–246
7 247–272
8 273–298
9 299–323
10 324–348

Source: Drinking-water Standards for New Zealand 2005, p. 129.

Returning to Regulations 7 and 8, the consent application should address whether the water delivered by the supply that may be affected by the activity currently complies or does not comply with the health quality criteria.

Information about whether or not drinking water supplies comply with the health quality criteria is contained in the previously mentioned database supplied to regional councils by the Ministry for the Environment. This is developed from the Water Information New Zealand national database of health quality information on drinking water, maintained on behalf of the Ministry of Health by ESR. Public information on individual drinking water supply compliance with the DWSNZ is available at the website http://www.drinkingwater.org.nz/

Other parties who require information about the compliance status of a drinking water supply (eg, applicants or their agents) should contact a drinking water assessor at the public health unit for the district where the supply is located. The drinking water supplier could also be contacted for this information.

Different regulations apply to the water source depending on whether the source meets the criteria, and whether it is tested. In summary:

  • Regulation 7 applies to water that is tested and meets health quality criteria

  • Regulation 8(1) applies to water that is not tested, or water that has been tested but not in a way that complies with the DWSNZ requirements

  • Regulation 8(2) applies to water that has been tested but does not meet health quality criteria.

Each of these regulations is explained in more detail in section 4.6 below.

4.5.7 Step 7: Will the proposal have an adverse effect on the quality of the drinking water?

The final consideration is whether the proposed activity will affect the quality of drinking water. An initial assessment could ask the following questions.11

  • For a discharge permit, will the activity produce any:

    • determinands
    • aesthetic determinands (eg, sodium)
    • precursors of determinands (eg, dissolved organic matter)
    • substances that reduce the efficiency of disinfection (eg, sediment).
  • For a water permit, will the activity substantially reduce the assimilative capacity of the receiving water to the extent that concentrations of determinands (or precursors) may increase in the source water (eg, consideration of increased temperature because of decreased flows, which can lead to algal blooms)?

If the answer to these questions is Yes, then further work and assessment will be required before the consent can be granted. It may be useful to contact the operators of the treatment plant potentially affected at this stage (or before) as they may have relevant knowledge which could be helpful.

The NES allows different levels of effects depending on the current status of the drinking water. The different levels of effects are discussed in the explanations of Regulations 7 and 8 in section 4.6 below.

4.6 More detail on Regulations 7 and 8

4.6.1 Regulation 7

[7] Granting of water permit or discharge permit upstream of abstraction point where drinking water meets health quality criteria

A regional council must not grant a water permit or discharge permit for an activity that will occur upstream of an abstraction point where the drinking water concerned meets the health quality criteria if the activity is likely to –

(a) introduce or increase the concentration of any determinands in the drinking water, so that, after existing treatment, it no longer meets the health quality criteria; or

(b) introduce or increase the concentration of any aesthetic determinands in the drinking water so that, after existing treatment, it contains aesthetic determinands at values exceeding the guideline values.

Regulation 7 applies to water supplies that currently meet the health quality criteria. More specifically, it applies to applications for activities that can affect the quality of a drinking water source where the drinking water currently meets the health quality criteria, as specified in Regulation 4.

Regulation 7 states that an activity is not allowed if it will increase the concentration of determinands in the water at the abstraction point to the extent that existing treatment cannot deliver water that is safe to drink. This requirement not only applies to determinands that may affect human health, but also to aesthetic determinands (see also Appendix 1).

In summary, if water is sufficiently tested and meets the health quality criteria, an activity cannot obtain consent if it will result in any determinand exceeding the MAV or guideline value (GV) in drinking water after existing treatment.

4.6.2 Regulation 8

Regulation 8 is more complex than Regulation 7 because it applies to two different circumstances. The first, as described in Regulation 8(1), is for a drinking water supply where water has not been adequately tested as required by the DWSNZ. The second circumstance, specified by Regulation 8(2), applies to drinking water that has been sufficiently tested but fails to meet the health quality criteria, which means this water already contains determinand levels above those specified by the MAV in the DWSNZ.

Regulation 8(1)

[8] Granting of water permit or discharge permit upstream of abstraction point where drinking water not tested or does not meet health quality criteria

(1) A regional council must not grant a water permit or discharge permit for an activity that will occur upstream of an abstraction point where the drinking water concerned is not tested in accordance with the compliance monitoring procedures in the Drinking-water Standard if the activity is likely to –

(a) increase the concentration of any determinands in the water at the abstraction point by more than a minor amount; or

(b) introduce or increase the concentration of any aesthetic determinands in the drinking water so that, after existing treatment, it contains aesthetic determinands at values exceeding the guideline values.

Regulation 8(1) states that if water supplied by a specific registered drinking water supplier is not sufficiently tested,12 then consent for an activity cannot be granted if that activity is likely to increase the concentration of any determinands in the water at the abstraction point. This is a more stringent requirement than that in Regulation 7, which discusses the concentration of determinands after treatment.

If water is not sufficiently tested, the level of contamination at its source cannot be increased. The reason behind this stricter requirement is public health protection. When a water supply is not tested, or is insufficiently tested, health authorities can not say whether the water is safe to drink. Limiting the increase of any determinands in the water at the abstraction point ensures there will be no increase in determinand concentrations after the existing treatment.

In other words, only one determinand needs to be insufficiently or incorrectly monitored for the drinking water supply to be classified as not sufficiently tested under Regulation 8(1).

Water that fits into this category (ie, has been tested, but not correctly) needs to be considered under the regulations as if it had not been tested at all. This precautionary approach is taken in the interest of public health, because without appropriate testing the quality of the water can not be determined and therefore the water can not be considered safe for human consumption.

Example: monitoring not adequate

Consider a plant with the following test results:

  Treatment plant number Determinand Adequately monitored (in accordance with DWSNZ) Too many exceedances of maximum acceptable values?  
TP09999 E. coli No Unknown*
  Arsenic Yes No

In this example, two determinands require monitoring. For this supply, monitoring is adequate for arsenic, but not for E. coli (because E. coli has not been correctly monitored). Therefore, drinking water from this supply is considered not to have been tested in accordance with the compliance monitoring procedures in the DWSNZ. As a result, applications for new water or discharge consents which could affect this drinking water supply would fall under Regulation 8(1).

* As E. coli is not adequately monitored (eg, an insufficient number of samples have been taken), it is not possible to assess whether the MAV for E. coli is exceeded.

Regulation 8(2)

[8] Granting of water permit or discharge permit upstream of abstraction point where drinking water not tested or does not meet health quality criteria

(2) A regional council must not grant a water permit or discharge permit for an activity that will occur upstream of an abstraction point where the drinking water concerned does not meet the health quality criteria if the activity is likely to –

(a) increase, by more than a minor amount, the concentration of any determinands in the water at the abstraction point that in the drinking water already exceed the maximum acceptable values for more than the allowable number of times as set out in Table A1.3 in Appendix 1 of the Drinking-water Standard; or

(b) increase the concentration of any determinands in the water at the abstraction point that in the drinking water do not exceed the maximum acceptable values for more than the allowable number of times as set out in Table A1.3 in Appendix 1 of the Drinking-water Standard to the extent that the drinking water, after existing treatment, exceeds the maximum acceptable values for more than the allowable number of times as set out in the table in relation to those determinands; or

(c) introduce or increase the concentration of any aesthetic determinands in the drinking water so that, after existing treatment, it contains aesthetic determinands at values exceeding the guideline values.

Regulation 8(2) applies to source waters for supplies where the drinking water has been sufficiently tested, but at least one determinand does not meet health quality criteria. In these circumstances two criteria apply. The first, specified in 8(2)(a), applies to determinands that already exceed maximum acceptable values specified in the DWSNZ:

(a) increase, by more than a minor amount, the concentration of any determinands in the water at the abstraction point that in the drinking water already exceed the maximum acceptable values for more than the allowable number of times as set out in Table A1.3 in Appendix 1 of the Drinking-water Standard.

Example: MAV for one determinand already exceeded

A drinking water treatment plant has been sufficiently tested and the MAV for E. coli is already being exceeded. In this circumstance, Regulation 8(2)(a) requires that any new activity for which a water or discharge permit is being sought cannot be granted if the activity is likely to increase concentrations of E. coli by a more than a minor amount at the abstraction point.

Different criteria apply in a situation where the supply may be complying with maximum acceptable values for some determinands but not for others. Regulation 8(2)(b) applies specifically to those determinands that are currently complying with the MAV specified by the DWSNZ:

(b) increase the concentration of any determinands in the water at the abstraction point that in the drinking water do not exceed the maximum acceptable values for more than the allowable number of times as set out in Table A1.3 in Appendix 1 of the Drinking-water Standard to the extent that the drinking water, after existing treatment, exceeds the maximum acceptable values for more than the allowable number of times as set out in the Table in relation to those determinands;

For example, if a supply is not providing safe drinking water but it complies with the criteria for E. coli specified in the DWSNZ, then Regulation 8(2)(b) states that the concentrations of this determinand in the drinking water after existing treatment should not exceed the MAV specified in the DWSNZ.

Therefore, an activity that produces additional E. coli may only be granted consent if the concentration of E. coli at the abstraction point will not be increased to a level that the existing treatment plant cannot safely treat. In other words, the consent cannot be granted if the activity will result in the water exceeding the DWSNZ for E. coli. (This case is similar to that of Regulation 7.)

The reason for this approach is to provide some flexibility in situations where a treatment plant may be adequately removing some contaminants but not others.

The circumstances in which Regulations 7 and 8 apply are summarised in Figure 6 on the following page.

Example: one MAV exceeded and one not

A supply currently complies with the MAVs for E. coli but not for arsenic. This supply is tested in accordance with the DWSNZ, so Regulation 8(2) applies.

Because the supply water does not currently comply with the MAV for arsenic, the test for a consent that would discharge arsenic is more stringent than if E. coli would be discharged. Consent for an activity that would discharge arsenic into the source water upstream from the abstraction point could be granted only if the proposal will not result in an increase in the level of arsenic in the water at the abstraction point which is more than minor (Regulation 8(2)(a)).

A consent for an activity that releases E. coli can be granted as long as the water will still meet the MAV for E. coli after treatment.

A precautionary approach is taken because the current treatment plant is known not to sufficiently remove arsenic to protect public health. Therefore, from a health perspective any further increase in the level of arsenic in the finished water is unacceptable.

 

Figure 6: Summary of Regulations 7 and 8

Figure 6 diagrammatically represents how regulations 7 and 8 apply, depending on the compliance of a drinking water supply with the DWSNZ.  This is explained more fully in the text of this chapter (pages 27 to 34).

* MAV = maximum acceptable value.

** Regulation 8(2)(b) applies where two or more determinands are produced by an activity and one of the determinands does not currently exceed its MAV in treated drinking water.

4.7 Applying the national environmental standard to determinands that were not previously monitored

The following examples give an idea of how the NES can be applied to determinands that have not previously been monitored. Note that chemical contaminants are only monitored if the Ministry of Health requires a specific supply to do so, based on risk factors in a catchment. Concentrations of chemical contaminants that do not require monitoring are assumed by the Ministry of Health to be below MAVs for that supply.

Example: new determinand; currently no MAVs exceeded

A water supply monitors E. coli and arsenic for compliance with the DWSNZ. For this supply monitoring is carried out in accordance with the DWSNZ and no MAV is exceeded for the measured determinands. Therefore Regulation 7 applies when processing a resource consent application for an activity that may affect the source for this supply.

Regulation 7 applies even if an application is made for an activity that will, for example, discharge nitrate to water, even though nitrate has not previously been monitored for this drinking water supply.

Example: new determinand; currently one MAV compliant, one exceeded

A drinking water supply monitors E. coli and arsenic for compliance with the DWSNZ. The monitoring is done in accordance with the DWSNZ. E. coli complies but arsenic exceeds its MAV. This means that consent applications for activities upstream must be assessed under Regulation 8(2).

An applicant is seeking resource consent for a discharge that includes E. coli, arsenic and nitrate. Different parts of Regulation 8(2) apply when assessing an application for resource consent, depending on which contaminant is discharged by the activity.

Regulation 8(2)(a) applies for arsenic. Because arsenic exceeds the MAV, a consent can not be granted if the activity will increase the concentration of arsenic at the abstraction point by more than a minor amount.

Regulation 8(2)(b) applies for E. coli and nitrate. Because E. coli concentrations in the water supply are below the MAV, the effects of the activity are assessed in terms of what the concentrations of E. coli will be in the drinking water after existing treatment (Regulation 8[2][b]).

Nitrate is not monitored for this drinking water supply. However, it is assumed that the concentrations of nitrate are below the MAV. Chemical contaminants are only monitored if the Ministry of Health requires a specific supply to do so, based on risk factors in a catchment. As explained above, concentrations of chemical contaminants that do not require monitoring for that supply are assumed by the Ministry of Health to be below MAVs. Therefore, the effects of the activity for nitrate will be assessed based on what the post-consent concentrations of nitrate would be in the drinking water after existing treatment (Regulation 8[2][b]).

More information on monitoring chemical contaminants in drinking water can be found in Appendix 1.

4.8 Aesthetic determinands

Aesthetic determinands do not have direct adverse health effects. However, elevated levels of aesthetic determinands are still of public health importance. If drinking water is unpleasant to taste or smell, people may use alternative sources of water (eg, untreated aquifer or river water), which may not be safe.

An aesthetic determinand is defined in the DWSNZ as:

A constituent or property of the water that can adversely affect the water’s taste, odour, colour, clarity or general appearance, including substances such as manganese and iron compounds that can stain washing and utensils.

The NES manages aesthetic determinands differently from determinands of health significance because they are not required to be tested under the DWSNZ. The regulation requires that aesthetic determinands be benchmarked against something measurable. The requirement that aesthetic determinands not exceed guideline levels after existing treatment gives councils and applicants a threshold for decision-making.

Most drinking water treatment plants do not routinely monitor aesthetic determinands because their testing can be expensive and it is not required by the DWSNZ. This can create difficulties when estimating concentrations of aesthetic determinands in finished water, given the concentration in the source water is unknown.

To assess the effects of an activity on aesthetic determinands, we suggest applicants follow these steps.

  1. Estimate the concentration of an aesthetic determinand arising from an activity at the abstraction point for a drinking water treatment plant.
  2. Estimate the concentration of the aesthetic determinand that will be present in the treated drinking water after the water has passed through the existing treatment process at the plant.
  3. Compare the estimated concentration of the aesthetic determinand in the treated water with the guideline value given in Table A2.1 of the DWSNZ.

Once again, the onus is on the applicant to prepare an assessment of all of the effects of their proposed activity on the environment. If the information provided is not sufficient, then more information should be requested (under section 92 of the RMA). Councils simply need to assess and evaluate this assessment as they would for any other effect.

Example: consent sought for an activity that generates an aesthetic determinand

An applicant is seeking resource consent for an activity that generates ammonia as a waste product. Ammonia can have an unpleasant odour above certain concentrations. The current concentration of ammonia in the source water is unknown, but the treatment plant operator has not received any complaints about the smell of the water (note that ecological values may have lower ammonia thresholds than drinking water values), so the concentrations are assumed to be below the guideline value for ammonia (1.5 mg/L).

The applicant has several samples of water from near the abstraction point analysed for ammonia. This shows an average ammonia concentration of 0.3 mg/L. Calculations show that the proposed new activity will lead to an increase in ammonia concentrations of 0.5 mg/L above the existing concentrations at the abstraction point (taking into account dilution, etc). This means there will be a total ammonia concentration of 0.8 mg/L at the abstraction point.

As this is well below the aesthetic guideline value of 1.5 mg/L, the NES will not cause the consent to be declined.

It should be noted, however, that ammonia can have adverse ecological effects at lower concentrations than those that cause aesthetic problems for humans. Thus the consent may be declined on other grounds, or have to be modified before the proposal can be granted.

8 The database is available only to regional councils because it contains technical data on aspects of supply monitoring and performance relevant to individual supplies, which can be commercially sensitive and requires Ministry of Health permission for distribution. It is not necessary for understanding the quality of the water supplied for public health purposes; public information on individual drinking water supply compliance with the DWSNZ is available at the website http://www.drinkingwater.org.nz/. It is also restricted because it contains technical information relevant only to individual plants, which is not necessary for other plant operators or water suppliers to know. It is made available to regional councils only because each region contains many water supplies for which the council will need technical information to implement the NES. Some simplified information (ie, the location of abstraction points from source water for individual treatment plants) will be made available by the Ministry for the Environment to territorial authorities to assist with the implementation of Regulations 11 and 12.

9 The RMA definition of contaminant is (emphasis added):

‘Contaminant’ includes any substance (including gases, odorous compounds, liquids, solids, and micro-organisms) or energy (excluding noise) or heat, that either by itself or in combination with the same, similar, or other substances, energy, or heat –

(a) when discharged into water, changes or is likely to change the physical, chemical, or biological condition of water; or

(b) when discharged onto or into land or into air, changes or is likely to change the physical, chemical, or biological condition of the land or air onto or into which it is discharged.

10 The NES definition of determinand states: “Determinand means a determinand described in Table 2.1, 2.2, 2.3, or 2.4 of the DWSNZ”.

11 In many cases this will require technical assessment by a qualified professional as part of an applicant’s assessment of environmental effects.

12 ‘Tested’ is defined in the NES in Regulation 4(1)(b) as “is tested in accordance with the compliance monitoring requirements in the Drinking-water Standard”. More details of the required testing required by the DWSNZ are included in the report A Guide to the Ministry of Health Drinking-water Standards for New Zealand by ESR, available from the Ministry for the Environment's website here