surface and groundwater sources version 2, ref s1...plan guide: surface and groundwater sources,...

Water Safety Plan Guide

Surface and Groundwater Sources Version 2, Ref S1.1

January 2014

Citation: Ministry of Health. 2014. Water Safety Plan Guide: Surface and groundwater sources, version 2, ref s1.1. Wellington: Ministry of

Health.

Published in January 2014 by Ministry of Health

PO Box 5013, Wellington, New Zealand

ISBN: 978-0-478-41598-8 (print) ISBN: 978-0-478-41599-5 (online)

Previously published in 2002 as Public Health Risk Management Plan Guide: Surface and groundwater sources, version 2, ref s1.1. This publication’s title and any reference within the text to ‘public health risk management plan’ was changed in January 2014 to

reflect legislation change of the term ‘public health risk management plan’ to ‘water safety plan’. No other changes have been made to this

document.

This document is available at: www.health.govt.nz

Ref S1.1 Water Safety Plan Guide: iii Version 2, January 2014 Surface and Groundwater Sources

Contents

Introduction 1

Risk Summary 2

Risk Information Table 3

Contingency Plans 16

Water Safety Plan Performance Assessment 20

Appendix (S1.1): Source Protection Zones (SPZ) 21

Risk Estimation Explanatory Notes 22

Ref S1.1 Water Safety Plan Guide: 1 Version 2, January 2014 Surface and Groundwater Sources

Introduction Raw water is groundwater, surface water or rainwater that has not received any treatment to make it suitable for drinking. This Guide is concerned with groundwater and surface water; rainwater is covered in Guide S1.2. The quality of the raw water must be good enough to produce a safe and acceptable drinking-water when treated, and it must come from a source that can consistently provide sufficient required quantity. In many cases it can be better to protect the quality of the raw water than to treat it after it has become contaminated. Contaminated and poorly managed water sources can contain chemical, microbiological or radiological hazards which can lead to sickness. This Guide considers four methods for managing risks to raw water quality:

• regulation of activities by law (Resource Management Act 1991 – RMA)

• increasing people’s awareness of the effects their activities have on the drinking-water supply

• increasing awareness of natural activities and processes, so that the risks to raw water quality they create can be managed

• co-operation and communication with landowners whose activities can affect raw water quality; being aware of planned activities that might affect water quality.

These methods require water suppliers to work alongside regional and district councils and unitary authorities. The RMA can be used to manage some risks to raw water quality arising from land use activities. However, there are a number of risks that are not easy to manage using the RMA and interpretation of it differs among regional and district councils so that risk management is sometimes unsatisfactory. Law changes have not been suggested as a way of managing raw water quality, although these may be necessary if water suppliers are to have the information and the powers they need to manage their supplies effectively. Raw water quality has effects on many other supply elements, especially treatment processes. This Guide is therefore linked to a number of other Guides: those dealing with abstraction from the source (P1 series), pre-treatment processes (P4 series) and the various treatment processes (P5, P6, P7 and P8 series).

2 Water Safety Plan Guide: Ref S1.1 Surface and Groundwater Sources Version 1, January 2014

Risk Summary The events associated with raw water that create the greatest risks are animal or human waste (see S1.1.7, S1.1.13), or toxins from algae (see S1.1.21), getting into the source water, and not being able to draw enough water (see S1.1.22). The most important preventive measures are:

• monitoring, to decide if and where contamination of the water is occurring; this is best done when contamination is most likely

• knowing where the catchment (surface water) or re-charge zone (groundwater) of your source is and the nature of the land in this area

• identifying source protection zones for your source, so that possible contamination sources that need to be managed can be identified (source protection zones are discussed in the Appendix to this document)

• collection of all available information about possible sources of contamination – identifying gaps in information is an important part of this Guide.

(References in parentheses are to the Risk Information Table.)


Risk Information Table Estimates of the level of risk are provided for each event in this table. These are a guide only. The nature of each individual source, and the activities and land-use around it, will affect the actual level of risk. Some factors listed below will help you in estimating the level of risk for each event for you supply:

• An activity that is absent does not present a risk.

• In general, the closer an activity is to where you draw water from the source, the greater the chance of contamination (so long as the separation is not great).

• Continuing contamination is more likely, and the risk therefore higher, if there is already evidence of contamination.

• Activities leading to germs getting into the water generally create a greater risk to public health than those leading to chemical hazards.

In the Appendix there is a section entitled “Risk estimation explanatory notes”. These comments are intended to help in deciding how the characteristics of your source may affect the level of risk for each event in the Risk Information Table. Reliable information about water quality is essential for the proper management of a water supply. Knowledgeable and skilled staff are also essential for minimising the public health risks associated with water supplies. Please read the staff training guide (G1) and the monitoring guides (G2). While we haven’t pointed out every detail of how these documents are linked with the present document, the links are many and are important.


Abbreviations: DWSNZ – Drinking-Water Standards for New Zealand; MAV – Maximum acceptable value – see DWSNZ:2000. Council – unitary authority, regional council, or district council depending on the area concerned.

Causes Preventive measures Checking preventive measures Corrective action

What to check Signs that action is needed

Event: SOURCE WATER RECEIVES DISCHARGE OR LEACHATE FROM A CONTAMINATED SITE (including sheep dips, offal, tannery pits and carcass pits). Possible hazards: Germs; chemical determinands (depending on nature of site). Level of risk: Moderate-high

S1.1.1

• Contaminated sites close enough to source water to potentially affect its quality.

• Poor understanding of catchment or recharge zone.

• Poor identification of source protection zones.

• No knowledge of the contaminant’s existence.

• Possible effects of sites not recognised when source development consent was obtained.

• New contaminated site.

• Identify the source catchment or recharge zone, and source protection Zones I, II and III (see Appendix).

• Obtain all information available about known contaminated sites in the catchment or recharge zone.

• Once all contaminated sites have been identified, establish a strategy to: – develop a list of possible

contaminants – monitor water quality for

evidence of health-significant contaminants,1 and request the council to oversee site clean-up

– develop a plan with the council using monitoring and site inspection to provide early-warning of source contamination

– work with the council to identify and carry out measures that can be put in place to control the spread of contaminants.

• Arrange for water supplier to be informed of new discharge consent applications in the source protection zone.

• E. coli in raw water (12 consecutive monthly samples).

• Any chemical determinand that might possibly be present in the contaminated sites.

• Median E. coli count over 12 months is more than 500/100ml.

• Elevated levels of contaminants in source water.

• Reticulated water not compliant with DWSNZ: 2000.

• Lack of knowledge of catchment/ recharge zone, and contaminated sites in the area.

• Gather more information about catchment or recharge zone.

• Approach council for information about contaminated sites.

• Arrange for council to establish strategy to deal with the effects of any contaminated sites.

• Consider treatment options or development of a new source.

1 The monitoring plan should take into account seasonal changes, as lower flows can lead to lead to higher contaminant concentrations. Situations in which contamination is most likely to occur should be identified so that monitoring can be suitably timed.




Event: SOURCE WATER RECEIVES DISCHARGE FROM DOMESTIC OR INDUSTRIAL PROCESSES, EITHER DIRECTLY OR INDIRECTLY (excluding septic tanks) Possible hazards: Germs; chemical determinands (depending on the nature of the discharge). Level of risk: Moderate-high

S1.1.2

• Non-permitted or permitted activities2 within the source protection zone.


• No, or incomplete, knowledge of activities in the catchment or recharge zone.

• Insufficient consideration of potential impact of activities when consents granted.

• Council plan classes activity as permitted, and hence consent conditions do not exist.


• Conditions of the consent are not followed.

• Develop an understanding of the extent of the source catchment or recharge zone. Identify source protection Zones I, II and III.

• Obtain information about non-permitted activities in the catchment or recharge zone from the council.

• Obtain a list of permitted activities that are potential causes of contamination.

• Obtain information about permitted activities in the catchment or recharge zone by survey if not available elsewhere.

• Once all discharges are identified, liaise with council to establish a strategy to: – develop a list of possible

contaminants with distance from abstraction point

– monitor water quality for evidence of health-significant contaminants,1 and request that the council arrange for reduction of contaminant loading (if necessary)

– obtain monitoring results from consent holders

– develop a plan with the council using monitoring and site inspection to provide “early-warning” of source contamination

– work with the council to identify and carry out measures that can be put in place to control the spread of contaminants.

• Ensure water supplier is informed of new discharge consent applications in the source protection zone.


• Any chemical determinand that might possibly be present in the discharge.


• Elevated levels of chemical contaminants in source water.


• Lack of knowledge of catchment/ recharge zone, and sources of contamination in the area.

• Obtain more information about catchment or recharge zone.

• Approach councils for information concerning non-permitted activities in the area.

• Establish strategy to deal with the effects of any discharge (eg, deep abstraction).



2 Permitted activities are defined in regional and district plans. These are activities for which no resource consent is required, and because of this, councils often hold very little information that would help in managing them. The risks they create are often from non-point sources of contamination, rather than point sources.




Event: SOURCE WATER RECEIVES DISCHARGE FROM MINING OPERATIONS Possible hazards: Metal determinands and cyanide (depending on the ore and extraction process). Level of risk: Low-moderate

S1.1.3 Non-permitted or permitted activities2 within the source protection zone (see S1.1.2).

See S1.1.2.

Event: SOURCE WATER RECEIVES LEACHATE FROM LANDFILL SITE Possible hazards: Germs; chemical determinands. Level of risk: Moderate

S1.1.4 • Non-permitted activity

within the source protection zone.


• No, or incomplete, knowledge of activities in the catchment or recharge zone.

• Insufficient consideration of potential impact of activities when consents granted.

• Poorly constructed landfill. • Landfill liner is damaged. • Inappropriate use of

landfill (eg, wrong type of waste dumped).


• Conditions of the consent are not followed.

See S1.1.2.

Event: SOURCE WATER RECEIVES WASTE ORIGINALLY DISCHARGED TO LAND Possible hazards: Germs; chemical determinands. Level of risk: Moderate-high

S1.1.5 Non-permitted or permitted activities2 within the source protection zone (see S1.1.2).

See S1.1.2.

Event: SOURCE WATER RECEIVES SPILLAGE, OR LEAKAGE, ARISING FROM THE STORAGE OR USE OF HAZARDOUS SUBSTANCES Possible hazards: Germs; chemical determinands (depending on the nature of substances in use). Level of risk: Moderate-high

S1.1.6 Non-permitted or permitted activities2 that use hazardous substances within the source protection zone (see S1.1.2).

See S1.1.2.

2 Permitted activities are defined in regional and district plans. These are activities for which no resource consent is required, and because of this, councils often hold very little information that would help in managing them. The risks they create are often from non-point sources of contamination, rather than point sources.




Event: SOURCE WATER RECEIVES SEPTIC TANK DISCHARGES Possible hazards: Germs; chemical determinands (predominantly nitrate and nitrite). Level of risk: High

S1.1.7 Septic tanks within the source protection zone (see S1.1.2).


• Obtain information about the number and location of septic tank discharges in the catchment or recharge zone.

• Liaise with councils to identify all septic tank disposal fields located within source protection Zone II.

• Request that the council decline new applications for septic tank installation within source protection Zone II.

• Once the location of septic tank discharges are known, establish a strategy to: – monitor water quality for

evidence of health-significant contaminants1

– develop a plan with the council using monitoring and site inspection to provide ‘early-warning’ of source contamination

– in collaboration with councils, provide public information on recommended maintenance and use of septic tank systems

– identify and carry out measures that can be put in place to control contamination from the existing discharges.


• Nitrate.

• Nitrite.


• Elevated levels of nitrate, nitrite in source water.



• No information to allow establishment of satisfactory separation between bores/wells and tanks.

• Get more information about catchment or recharge zone.

• Approach council for information concerning discharge consents for septic tanks in the area.

• Establish strategy to deal with the effects of any septic tanks that are affecting the source.

• Consider treatment options (particularly disinfection – see P7 Guide series) or development of a new source.

1 The monitoring plan should take into account seasonal changes, as lower flows can lead to higher contaminant concentrations. Situations in which contamination is most likely to occur should be identified so that monitoring can be suitably timed.




Event: SOURCE WATER RECEIVES RUN-OFF FROM URBAN OR SEALED SURFACES Possible hazards: Germs; chemical determinands. Level of risk: Moderate-high

S1.1.8

• Urban or industrial area within source protection zone.


• Poor identification of areas where run-off may be influenced by land use activities.

• Inadequate collection, or treatment, of run-off, and inappropriate disposal.

• New activity in source protection zone.


• Obtain information about all sources of urban and industrial run-off and its treatment and disposal in the catchment or recharge zone.

• Once the presence of run-off sources is known, establish a strategy to: – monitor water quality for

evidence of health-significant contaminants,1 and request the council manages arrangements for reduced contaminant loading (if necessary)

– in association with councils, assess the risk management of areas where hazardous substances are stored and used, or high contaminant loading is expected (eg, petrol stations). Work with owners and councils to address any inadequacies

– develop a plan with the council using monitoring and site inspection to provide ‘early-warning’ of source contamination

– in collaboration with councils, provide public information on run-off from domestic activity and its impact on the water source

– identify and carry out measures that can be put in place to control contamination from run-off.

• Ensure water supplier is informed of new discharge consent applications in the source protection zone.


• Any chemical determinand that might possibly arise from activities in the catchment.



• Treated water not compliant with DWSNZ: 2000.



• Identify areas where land use is likely to affect run-off.

• Establish strategy to deal with the effects of contaminated run-off.


Event: SOURCE WATER RECEIVES MATERIAL FROM SURFACE IMPOUNDMENTS (WASTE PONDS OR LAGOONS) EITHER TREATED DISCHARGE OR LEAKAGE Possible hazards: Germs; chemical determinands. (depending on the nature of substances contained in the ponds). Level of risk: Low-high

S1.1.9 Impoundments within source protection zone (see S1.1.2).

See S1.1.2.





Event: SOURCE WATER RECEIVES TREATED EFFLUENT OR UNTREATED (LEAKAGE) FROM EFFLUENT PONDS Possible hazards: Germs; chemical determinands. (depending on the nature of the waste). Level of risk: Low-high

S1.1.10 Effluent ponds within source protection zone (see S1.1.2).

See S1.1.2.

Event: SOURCE WATER QUALITY INFLUENCED BY WASTE DISPOSAL DOWN HOLE OR BORES Possible hazards: Germs; chemical determinands. (depending on the nature of the waste). Level of risk: Moderate-high

S1.1.11 Waste disposal down holes or bores within source protection zone (see S1.1.2).

See S1.1.2.

Event: SOURCE WATER RECEIVES LEAKAGE OF CONTAMINANTS DOWN ABANDONED OR DECOMMISSIONED WELLS Possible hazards: Germs; chemical determinands. Level of risk: Moderate-high

S1.1.12 Abandoned or improperly decommissioned wells within source protection zone (see S1.1.2).

See S1.1.2.

Event: SOURCE WATER RECEIVES FAECAL MATTER FROM LIVESTOCK OR FERAL ANIMALS Possible hazards: Germs; chemical determinands. Level of risk: High

S1.1.13

• Animals within source protection zone.



• Limit stock density and irrigation of pastures in source protection Zone II so that faecal material does not pass into the groundwater. (Councils may be able to provide advice on the limits for stock numbers that will protect the water resource.)

(See P1 Guide series.)


• Nitrate.

• Nitrite.


• Elevated levels of nitrate or nitrite in source water.


• Lack of knowledge of catchment/ recharge zone.

• Stock with access to source water.

• Improve information available about catchment or recharge zone.

• Erect stock fence an appropriate distance from the source, and make sure stock are removed.




Event: AGRICHEMICALS (INCLUDING STOCK DIP) OR POISONS ENTER SOURCE WATER Possible hazards: Chemical determinands (depending on the nature of the agrichemicals). Level of risk: Low-moderate

S1.1.14

• Agrichemical and/or poison use within source protection zone.


• Inappropriate location of stock dips.

• Inappropriate construction of stock dips and post dip drainage area.

• Inappropriate disposal of used dip.

• Poor understanding by the farmer of the potential consequences of their farming practices.

• Lack of backflow prevention measures in chemical preparation facilities.


• Identify farming activities in the area. Prepare a list of agrichemicals used for these farming activities.

• Monitor water quality for evidence of health-significant contaminants,1 and request that the council manage arrangements that will help to reduce the contaminant loading.

• Ensure farmers are aware of codes of practice (if applicable) for agricultural chemical use, and the need for backflow prevention for their source water.

• Chemical determinands (depending on the agrichemicals in use).

• Concentrations of agrichemicals more than 50% of their MAV in the source water.


• Lack of knowledge of catchment/ recharge zone.

• Agrichemicals still being applied in a way that is likely to contaminate the source.


• Approach the council and MAF to arrange a seminar for farmers on good practices with respect to use of agrichemicals and poisons.





Event: CONTAMINANTS WASHED INTO SOURCE WATER DURING IRRIGATION Possible hazards: Germs; chemical determinands. Level of risk: Moderate-high

S1.1.15 Irrigation being undertaken within source protection zone.


• Ensure that farmers use appropriate irrigation systems for effective coverage without causing flooding.


• Chemical determinands (particularly nitrate and nitrite).

• Increasing conductivity of the water.

• Appearance of algal blooms.




• Farmers unaware of possible effects of irrigation.

• Development of algal blooms.

• Signs of salt migration into groundwater from the soil salinisation.

• Approach the council and MAF to arrange a seminar for farmers on good irrigation practices.

• Start periodic inspections of the catchment.

Event: SOURCE WATER RECEIVES SEDIMENT AND AGRICHEMICALS FROM FORESTRY ACTIVITIES Possible hazards: Germs; chemical determinands. Level of risk: Low

S1.1.16 Poor forestry management practices.


• Identify forestry in the source protection zone, and monitor water quality for evidence of health-significant contaminants.1 Where there is high contaminant loading seek assistance from the forestry company and council in reducing it.

• Seek assistance from the forestry company in making its workers aware of how their activities can affect source water quality. Correct practices should be compiled in a code of practice.

• Request erosion management plans from the forestry company when logging activities are planned, or new ground is prepared for planting.


• Chemical determinands (particularly agrichemicals used in forestry).

• Turbidity.


• Elevated levels of contaminants (including turbidity) in source water.


• Unsatisfactory practices still being used in the management of the forest.

• Visit forest owners to discuss how forestry management can affect source water quality.

• Start periodic inspections of the catchment.





Event: FERTILISER ENTERS SOURCE WATER DURING APPLICATION Possible hazards: Nitrate/nitrite; algal/cyanobacterial toxins from blooms caused by the nutrients. Level of risk: Low-high

S1.1.17

• Application of fertiliser in the catchment or recharge zone.

• Farmer unaware of the extent of the catchment or recharge zone.

• Poor fertiliser application practices.


• Gather information on the use of fertiliser in the source protection zone, and monitor water quality for evidence of health-significant contaminants.1 Where there is a high contaminant loading, seek assistance from the council in reducing it.

• Inform farmers with property in the catchment or recharge zone of this, and the effects their activities can have on source water quality.

• Inform farmers of correct fertiliser application practices.

• Nitrate.

• Nitrite.

• Other nutrients that may contribute to eutrophication of source waters.

• Algal/ cyanobacteria (bluegreen algae) counts.

• Elevated levels of contaminants, including algae/ cyanobacteria, in source water.


• Poor fertiliser application practices in use.

• Approach the council and MAF to arrange a seminar for farmers on good practices relating to fertiliser application.

• Lobby the council introduction of bylaw to limit fertiliser application (eg, through introduction of designated Nitrate Sensitive Areas).

Event: GEOTHERMAL CONTAMINANTS ENTER SOURCE WATER Possible hazards: Arsenic, boron, lithium and fluoride. Level of risk: Low-moderate

S1.1.18

• Geothermal activity in the source water catchment or recharge zone.

• Poor understanding of the catchment or recharge zone when the source was selected.

• No, or limited, water quality monitoring undertaken when selecting the source.

• Lack of information regarding the geology, and geothermal nature of the area.

• Before selecting a source in an area that may be subject to geothermal activity, undertake a monitoring programme for possible geothermal contaminants. From this determine whether they constitute a risk to public health, and if so, select another source. Extended monitoring may be required to determine whether their concentrations are changing with time (see Guide S2).

• Arsenic.

• Boron.

• Fluoride.

• Lithium.

• Concentrations of geothermal contaminants are more than 50% of their MAV in the source water.

• Reticulated water not compliant with DWSNZ:2000.

• New source developed with geothermal contaminant problems.

• Where an existing source is found to be contaminated, seek a second source of better quality. This should used instead of the existing source, or to dilute it, if its production is low.

• Obtain advice on appropriate treatment options.





Event: SOURCE WATER IN CONTACT WITH MINERAL DEPOSITS Possible hazards: Metals, fluoride (depending on the nature of the deposit). Level of risk: Low-moderate

S1.1.19

• Mineral deposit(s) in the catchment or recharge zone.

• Poor understanding of the catchment or recharge zone when the source was selected.

• No, or limited, water quality monitoring undertaken when selecting the source.

• Lack of information regarding the geology of the area.

• Before selecting a source in an area that may be subject to geothermal activity, undertake a monitoring programme for possible health-significant determinands. From this assess whether they constitute a risk to public health, and if so, select another source. Extended monitoring may be required to determine whether their concentrations are changing with time (see Guide S2).

• Heavy metals.

• Fluoride.

• Health-significant determinands are more than 50% of their MAV in the source water.

• Reticulated water not compliant with (note heavy metals due to corrosion are excluded) DWSNZ: 2000.

• New source developed with contaminant problems associated with minerals.



Event: SOURCE WATER INTRUDED BY SALINE WATER3 Possible hazards: Bromine-containing disinfection by-products brominated trihalomethanes (chlorination, chlorine dioxide, ozonisation) or bromate (ozonisation). Level of risk: Low-moderate

S1.1.20

• Bore too deep for its proximity to the sea.

• Abstraction of water too great leading to increased drawdown and ingress of seawater into the aquifer.

• Abstraction from other bores depresses water table.

• Changes in aquifer characteristics due to changes in meteorological conditions.

• Use a test bore to obtain water quality information when planning a source near the coast. Monitoring samples should be taken over a full tidal cycle, and data obtained during the lowest and highest tides.

• Ensure that the aquifer is properly developed and that its capacity to provide good quality water, at the maximum abstraction rate, is tested.

• Chloride.

• Conductivity.

• Chloride concentration more than its guideline value. (see DWSNZ: 2000).


• Complaints of salty taste.

• Finding sea-water intrusion in a new source.



3 Bromide in the water (from seawater) can lead to brominated disinfection by-products, and bromide is not removed by conventional treatment processes.




Event: SOURCE WATER EXPERIENCES ALGAL BLOOM Possible hazards: Algal/cyanobacterial toxins. Level of risk: High

S1.1.21 Conditions are suitable for algal growth:

– elevated nutrient levels

– sunshine

– warmth

– relatively still water.

• Take steps to limit nutrient concentrations in the source water (see S1.1.5, S1.1.7, S1.1.10, S1.1.13, S1.1.15, S1.1.17), starting with a survey of the catchment to identify any sources of nutrients.

• Temperature.

• Nutrient concentrations.

• Copper (from copper sulphate algicide).

• Algal or cyanobacterial toxins (as these analyses are expensive, sampling for these determinands should be targeted and used sparingly).

• Elevated levels of contaminants (nutrients and toxins) in source water.


• Complaints of symptoms consistent with toxin poisoning.

• Undertake catchment survey to determine nutrient sources.

• Start application of algicide earlier in future years (see Guide P4.1), or undertake destratification of the source water (see Guide P4.2).

(See also Figure and Table below.)

Event: NOT ENOUGH WATER AVAILABLE Possible hazards: Germs and chemicals that get into the water because of low system pressure; hazards associated with poor hygiene. Level of risk: High

S1.1.22 The causes, preventive measures, checks and corrective actions associated with this event are covered in each of the Guides dealing with abstraction from the source (see P1 Guide series).

Table (S1.1): Ability of oxidants to destroy cyanobacterial toxins

Oxidants Saxitoxin Microcystin Nodularin Cylindro-spermopsin

Ozone Yes# Yes Yes Yes

Chlorine No Yes Yes Yes

KMnO4 ? Yes ? ?

# When saxitoxin concentrations are low or moderate.

Ref: Steffensen D, Burch M, Nicholson B, Drikas M, and Baker P (1999) “Management of toxic blue-green algae (cyanobacteria) in Australia”, Environ. Toxicol., 14: 183–95.


Figure (S1.1): Rapid assessment of health hazard of a drinking-water supply system with possible toxic cyanobacteria at source

Figure based on a diagram from “Toxic Cyanobacteria in Water” (1999), Eds. I Chorus and J Bartrum, E & FN Spon, London.

Do you have advanced watertreatment facilities withozonisation and/or granularactivated carbon filtration?

Do you have regularmonitoring information toindicate potential forcyanobacteria in your watersupply source?

If cyanobacteria are present,could conditions lead to celllysis or rupture?

Is there likely to be effectiveremoval of cells by the watertreatment system in place?

Are the species present likelyto produce saxitoxins or

anatoxins?

Is chlorinationpractised?

Is chlorination beingoperated adequately to

destroy themicrocystins?

Relative risk ofhealth effects

Very High

High

Moderate

Low

Very Low

Conditions that can lead to cell lysis:• Use of algicides• Pre-chlorination• Senescent (eg late summer) bloom• Pumping regimes

Effective treatment methods:• Underground filtration• Coagulation/flocculation and filtration• Slow sand filtration

Taxa that can produce saxitoxins oranatoxins:• Aphanizomenon• Anabaena• Oscillatoria• Lyngbya• Cylindrosperum• Clyindrospermopsis

Chlorination conditions adequate todestroy microcystins requires 0.5mg/L free chlorine residual after afull 30 minutes contact time.Other cyanotoxins may not beinactivated under normalchlorination conditions.

No

Yes

No

No

No

Yes

No

No

No

Yes

Yes

Yes

Yes

Yes


Contingency Plans If an event happens despite preventive and corrective actions you have taken, you may need to consult with the Medical Officer of Health to assess how serious a problem is.

Event – Hazardous substances used or spilled from storage

Indicators: • Spill has been reported in the source protection zone.

• Elevated concentrations of hazardous substances, or their breakdown products, detected in the source water.

Required actions:

• Identify responsible body and inform relevant authorities including civil defence, if necessary.

• Ensure that spill is contained.

• Check quality of source water, use alternative drinking-water supply, if necessary and inform the public.

• Responsible body remediates area affected by spill.

• Monitor water quality to see whether corrective action has worked.

• Record incident and action taken.

• Request that responsible body document the incident and determine management procedures to prevent future spills

• Check quality of drinking-water throughout and at end of remedial work to determine whether alternative supply is needed.

• Determine whether there are any ways in which the source water can be protected from spills.

• Modify water safety plan (formerly known as a public health risk management plan, PHRMP) if necessary.

Responsibility: Manager designated responsible for the water supply must ensure that the source is protected. Body responsible for the spill must be responsible for all action to address the impact of the spill.


Event – Volcanic activity – leading to ash fall, pyroclastic flows and surges, lava flows, lahars, volcanic gases, landslides, tsunami, seiches and hydrothermal eruptions

Indicators: • Media coverage of activity.

• Notification from Institute of Geological and Nuclear Sciences.

Required actions:

• Normal range of conductivity and pH values need to be known (to provide baseline data, some monitoring needs to have been undertaken before the event).

• If conductivity values are not elevated and the pH is above 5, continue to use the source water. If conductivity is elevated (estimated increase of 5–10 mS/m), and pH is depressed below 5, inform MOH, use alternative source water or close the supply and obtain water from elsewhere until chemical analysis of the water shows it is acceptable, and inform the public.

• If turbidity is increased, take steps to make sure disinfection of the water is still effective.

• When the volcanic activity has ceased, measure conductivity, pH and other chemical determinands associated with the event until they return to normal range. Resume use of the source water.


• Modify water safety plan if necessary.

Responsibility: Manager designated responsible for the water supply.


Event – Extreme rain events

Indicators: • Quality of surface water visibly deteriorates.

• Sewer overflows occur.

Required actions:

• Increase frequency of measurements of turbidity, plus all other parameters that are critical to the satisfactory functioning of treatment processes.

• Increase disinfectant dose, if necessary, to make sure disinfection is still effective.

• If water quality is too poor to treat, use alternative source, or close the supply and obtain water from elsewhere until there is a return to acceptable levels, or issue ‘boil water’ notice. Inform MOH.

• See D2 Guide series for a contingency plan for the reticulation network.

• After extreme rain event, check all water supply infrastructure for maintenance requirements. Clean UV lamp if this form of disinfection is used.

• If source water is affected by rain events frequently, consider alternative source, or upgrade treatment to cope with the variability of source water quality (eg, pre-treatment storage).





Event – Earthquake

Indicators: • An earthquake may cause damage to the source, treatment plant or distribution system. The water supply may be shut down as a result.

Required actions:

• Contact the Ministry of Civil Defence in the event of an earthquake emergency. (Keep a list of the contact details for the nearest Ministry office and of the Earthquake Commission.)

• Check all structures associated with water storage, abstraction, treatment and distribution.

• If water supply structure is damaged so that water cannot be distributed, or cannot be distributed with a satisfactory quality, use alternative supply. Provide another source of potable water until water of acceptable quality can again be supplied. Contact the MOH.




Event – Water shortage

Indicators: • Low flow of rivers and springs, low level of lakes or dams, low water table of groundwaters.

• Unexpectedly high usage, or gradually increasing usage, due to increasing population.

Required actions:

• If low flow of river is the issue, determine whether water quality presents problems for adequate disinfection. Contact the MOH and issue ‘boil water’ notice if needed.

• Consider restricting water use.

• If water table has dropped to an extent where water can no longer be abstracted, use alternative source until water level has risen.

• If water shortages occur frequently, consider additional, or alternative source.





Water Safety Plan Performance Assessment To make sure that your supply’s water safety plan is working properly, periodic checks are needed. The Overview document outlines what needs to be done. The following table provides the detailed information for checking this particular supply element.

What to measure or observe:

• E. coli.

• High bacterial counts. • Protozoa if likely to be present in significant

numbers. • Chemical determinands expected from the source of

contamination. Follow the protocols set out in DWSNZ:2000.

How often: • See DWSNZ:2000 for E. coli and P2 determinands; minimum of twice per year (winter and summer) for all contaminants that are not P2 determinands, but that may arise from contaminant sources.

What to do with the results:

• Results need to be recorded to meet legislative requirements or to allow water safety plan performance assessment. The WINZ database is good for this.

• The collected data need to be periodically reviewed to see whether problems with this supply element are developing. This should be done as frequently as the manager responsible considers necessary to minimise risk to public health arising from this supply element.

• Should this review show any unusual incidents, indicate that proper procedures are not being carried out, highlight poor laboratory results or indicate that poor water quality is reaching customers, then review the procedures for managing raw water sources.

• Evaluate the monitoring results, and any actions taken as the result of having to implement a contingency plan, to see if the water safety plan needs modification – eg, preventive measures are up to date; the contingency plan steps are still adequate; any change to the source water used is recognised in the plan.



Appendix (S1.1): Source Protection Zones (SPZ) The actions needed to manage an activity that may contaminate your raw water will depend on the level of risk created by the activity. The level of risk is affected, amongst other things, by the closeness of the activity to the point where you draw water from the source (so long as the separation is not too great). SPZs are used in some countries to help assess the level of risk. This is done by identifying three areas, or zones, around the abstraction point. SPZ I is closest to the abstraction point, and activities within it present a high risk; those farthest away, in SPZ III, present a low risk. The methods for determining where these zones lie can be generally applicable, but the zones themselves will be specific to each source. New Zealand does not have a standard national method for defining SPZs, although some councils may have developed methods for deciding where SPZs lie. Seek advice from your regional council, district council or unitary authority as a first step in identifying SPZs for your source. Documents such as Guidelines for Delineation of Wellhead Protection Areas USEPA (1987) and Guide to Groundwater Protection Zones in England and Wales National Rivers Authority (HMSO) (1995) provide some indication of the methods used for identification of SPZs in the USA and UK. In the UK, the boundary for SPZ I is defined by a 50-day travel time of the water from that point to the source, and SPZ II by a 400-day travel time.


Risk Estimation Explanatory Notes Event Level of risk Comment

S1.1.1 Moderate-high • Germs present the greatest risk. • If leachate has had to travel some distance to the source, especially if it is

through the ground, this will have allowed time for some germs to die off, and so reduced the risk. Chemical contaminants will probably be unaffected.

• Higher risk arises from a discharge directly into the source water. Increased distance between the discharge and the point where water is taken from the surface water reduces the level of risk.

S1.1.2 Moderate-high • Germs present the greatest risk. • If leachate has had to travel some distance to the source, especially if it is

through the ground, this will have allowed time for some germs to die off, and so reduced the risk. Chemical contaminants will probably be unaffected.

• Higher risk arises from a discharge directly into the source water. Increased distance between the discharge and the point where water is taken from the surface water reduces the level of risk.

S1.1.3 Low-moderate • The level of risk will depend on the concentrations of chemical determinands in the water.

• Sickness caused by chemicals usually only arises after drinking the water for a long time. For this reason the level of risk associated with chemicals is not regarded as “high”. However, if an accident leads to very high chemical concentrations in the water, this should be dealt with by a contingency plan.

S1.1.4 Moderate • Germs present the greatest risk. • As this is leachate rather than a direct discharge, some die-off of germs while

the water is travelling underground is likely to reduce their numbers. The typical level of risk has not therefore been estimated as “high”. Chemical contaminants will probably be unaffected.

• If very high levels of germs can arise in the leachate, the level of risk may be higher than that indicated here.

S1.1.5 Moderate-high • Germs present the greatest risk. • The level of risk will be higher if there is surface run-off into the source water, or

if water is drawn from a shallow aquifer close to the area of waste disposal. • The level of risk will be less for deep bores, and when the distance between the

disposal area and the bore is large, because this allows more die-off of germs. Chemical contaminants will probably be unaffected.

S1.1.6 Moderate-high • Germs present the greatest risk, unless accidents result in very high chemical concentrations. These should be handled with contingency plans.

• The level of risk will decrease the farther the supply draw-off is from the leakage, and the greater the dilution by the receiving water (source).

S1.1.7 High • Germs present the greatest risk. • The level of risk will be highest when the bore is close to the tank, and the

groundwater flows in the direction of the bore.

S1.1.8 Moderate-high • Germs present the greatest risk. • The level of risk will be highest where there is a short travel time for the

contaminants to the draw-off for the water supply, and where there is little dilution by the receiving water (source).


Event Level of risk Comment

S1.1.9 Low-high • Germs present the greatest risk, unless accidents result in very high chemical concentrations. These should be handled with contingency plans.

• The level of risk will depend on the material held in the waste ponds. • Levels of risk will be lower for a treated discharge than an untreated leakage,

and where the discharge or leakage is being greatly diluted by the receiving water.

• If the material held in the ponds contains germs, the level of risk will also be reduced by a longer holding time in the ponds, and greater exposure to sunlight.

S1.1.10 Low-high • Germs present the greatest risk, unless accidents result in very high chemical concentrations. These should be handled with contingency plans.

• The level of risk will depend on the material held in the waste ponds. • Levels of risk will be lower for a treated discharge than an untreated leakage,

and where the discharge or leakage is being greatly diluted by the receiving water.

• If the material held in the ponds contains germs, the level of risk will also be reduced by longer holding time in the ponds, and greater exposure to sunlight.

S1.1.11 Moderate-high • Germs present the greatest risk. • Disposal close to the source bore may result in a high level of risk, especially if

the direction of groundwater flow is towards the source bore. • The level of risk will be lower when there is enough time before the water

reaches the draw-off of the supply for germs to die off. High levels of dilution by the receiving water (source) will also lower the risk. Chemical contaminants will be unaffected by die off.

S1.1.12 Moderate-high • Germs present the greatest risk. • Disposal close to the source bore may result in a high level of risk, especially if

the direction of groundwater flow is towards the source bore. • The level of risk will be lower when there is enough time before the water

reaches the draw-off of the supply for germs to die off. High levels of dilution by the receiving water (source) will also lower the risk. Chemical contaminants will be unaffected by die off.

S1.1.13 High • Germs present the greatest risk. • The level of risk from this event should always be regarded as “high”. However,

there may be some reduction in the level of risk if: – the number of animals having access to the water is small – there is a high level of dilution in the receiving water – there is sufficient time for some die-off of germs before the water reaches

the draw-off point.

S1.1.14 Low-moderate • Sickness caused by chemicals usually only arises after drinking the water for a long time. For this reason the level of risk associated with chemicals is not regarded as “high”. However, if an accident leads to very high chemical concentrations in the water, this should be dealt with by a contingency plan.

• Dilution by the receiving water, and reduction in the amount of chemical by decomposition or adsorption, will lower the level of risk.

S1.1.15 Moderate-high • Germs present the greatest risk. • The level of risk will be greater where stock numbers are high, the volume of

irrigation run-off is low (higher concentration of contaminants), and the receiving water has a low flow.

• Levels of contaminants in the water are likely to be highest in the first run-off reaching the receiving water.

S1.1.16 Low • Germs present the greatest risk when present, however, in most forestry situations, contamination by germs is expected to be low.

• Removal of germs during treatment may be made more difficult by sediment in the raw water.


Event Level of risk Comment

S1.1.17 Low-high • Algal toxins present the greatest risk from this event. Where there is no evidence of algal growth, level of risk from algal/cyanobacterial toxins will not be high.

• Nitrogenous fertiliser, if it leads to nitrate concentrations greater than the MAV in the receiving water, may present a moderate to high risk, otherwise the level of risk can be regarded as low.

S1.1.18 Low-moderate • The level of risk will depend on which determinands are present and their concentrations. Consistently low levels of these determinands will present a low risk.

• Catastrophic events, such as volcanic eruption, could result in very high concentrations of some of these contaminants. A contingency plan should be used to handle these situations.

S1.1.19 Low-moderate • The level of risk will depend on which determinands are present and their concentrations The concentrations of determinands in the water will be controlled mainly by the solubility of the mineral which is in contact with the source water.

• Contaminant concentrations from this source should be relatively constant, hence some monitoring, if contamination is suspected, will provide an indication of concentration and therefore level of risk.

S1.1.20 Low-moderate • Sickness caused by chemicals usually only arises after drinking the water for a long time. For this reason the level of risk associated with chemicals is not regarded as “high”.

• The level of risk can be regarded as low unless the concentrations of the brominated disinfection by-products are high.

S1.1.21 High • Unlike most chemical determinands, algal/cyanobacterial toxins at low concentrations can produce severe sickness in a short period of time.

• Where algal/cyanobacterial blooms occur frequently in a source water, the level of risk should be regarded as “high” until it can be demonstrated that the species of algae/cyanobacteria in the bloom do not produce toxins.

S1.1.22 High • Germs present the greatest risk when the quantity of water that can be obtained from a source is a problem.