Water Quality Risk ManagementMicrobial Risk Assessment and its management implications for Urban Water Supply Systems ** Risk matrix provided in the 2011Australian Drinking Water Guidelines

Local Government & Shires Association Water Management Conference, Wagga Wagga, 22-24 July 2012

Water Quality Risk Management:

Accounting for a Variable Climate

Dr Ryan Signor

Water & Environment – Risk Management Consultant GHD Water

A variable and uncertain climate will pose

challenges to water authorities.

Regardless, a safe and reliable water supply

will always be a major priority for

communities, and those who serve them.

• Future climate and weather patterns represent a

major uncertainty that requires monitoring,

management and planning

• Scenarios have been modelled based on storylines

about global responses to climate change

• Models are complex and there can be significant

variability among the scenario outputs; for example,

projections for Dubbo (NSW):

What to do about the weather? A1FI

B2

A2

B1

A1T

A1B

Greenhouse Gas Emission Scenarios to inform climate change

projections, from Intergovernmental Panel on Climate Change

(IPCC), 2007, Climate Change 2007: Synthesis Report.

Contribution of Working Groups I, II and III to the Fourth

Assessment Report of the Intergovernmental Panel on Climate

Change [Core Writing Team, Pachauri, R.K and Reisinger, A.

(eds.)]. IPCC, Geneva, Switzerland.

Climate change projections under

different year and emission scenarios

for Dubbo, NSW. From Appendix B of

Commonwealth Scientific and

Industrial Research Organisation and

Australian Bureau of Meteorology

(CSIRO & BoM), 2007, Climate

change in Australia: Technical Report

2007, Australian Government,

Canberra, Australia.

Risk is “the impact of uncertainty on objectives” (ISO 31000:2009)

Adaptive management involves a process of identifying objectives and continually

assessing, better understanding, monitoring and responding to the risks that a

changing climate may present to meeting them

Risk management lends itself to climate adaptation

Adaptive management for the water industry*

* The depicted planning cycle is Figure 1 from: Short et

al; 2012, ‘Managing Adaptation of Urban Water Systems

in a Changing Climate’, Water Resources Management,

26(7):1953-1981

“Ensuring drinking water safety and quality

requires the application of a considered

risk management approach…

This requires steering a sensible course

between the extremes of failing to act when

action is required and taking action when

none is necessary.”

Australian Drinking Water Guidelines (National Health & Medical Research Council, 2011)

• Risk management is de rigueur in Australia for managing drinking water quality, and this is

legislated in many Australian jurisdictions

• Opportunity exists to embed climate adaptation risk processes into existing drinking water quality

management planning requirements

• Advantages are that authorities can address multiple planning and operating needs in one activity

and it contextualises the climate risks to impacts on tangible water quality objectives

• Appreciate that both climate change and water quality risk management guides already

incorporate similar principles from the ISO 31000:2009 Risk Management standard

Water quality risk management in a changing climate

Presentation overview:

• Review of potential water quality and public health impacts

• Describes common components of water quality and climate change risk management

frameworks

• Addressing challenges for integrating the approaches

• Framework and information needs for addressing climate change within existing drinking water

quality risk management plans

Water quality risk management in a changing climate

Projected trends in NSW:

• Reduced long-term rainfall

perhaps with more intense

storm events

• Higher evaporation

• Diminished stream flow

• More prolonged droughts

• Exacerbate the characteristics

of the land of “drought and

flooding rains”

Water quality impacts of variable climate

Refer to:

Commonwealth Scientific and Industrial Research Organisation and Australian Bureau of Meteorology (CSIRO &

BoM), 2007, Climate change in Australia: Technical Report 2007, Australian Government, Canberra, Australia.

NSW Department of Environment, Climate Change and Water, 2010, NSW Climate Impact Profile, accessed 10 June

2012 at http://www.environment.nsw.gov.au/resources/climatechange/10171climateimpactprof.pdf

Potential impacts on drinking

water quality* (catch-to-tap):

• Reviews generally describe a

degrading trend if not managed

• Dissolved organic matter,

micropollutants and pathogens

may present greater

challenges

• Sea-level changes can affect

groundwater quality

• May impact treatment

efficiency and needs

Water quality impacts of variable climate

*For example:

Delpla et al; 2009, ‘Impacts of climate change on surface water quality in relation to drinking water production’, Environment International, 35:1223-1233 [NB: The figure on

this slide is Figure 1 from this article]

Hunter, P; 2003, ‘Climate change and waterborne and vector-borne diseases’, Journal of Applied Microbiology, 94:37S-46S

Cromwell, et al. (2010), ‘Implications of climate change for urban water utilities’, Association of Metropolitan Water Agencies, Washington DC. Accessed 10 June 2012 at

http://www.amwa.net/galleries/climate-change/AMWA_Climate_Change_Paper_12.13.07.pdf

Water Services Association of Australia; 2012, Climate Change Adaptation and the Australian Urban Water Industry, Occasional Paper #27

Risk frameworks for water quality & climate management

Risk Management Step (ISO 31000:2009)

Context setting

Risk identification

Risk analysis

Risk evaluation

Risk treatment

Monitor and review

Consult

Framework for drinking water quality, from the Australian Drinking Water Guidelines, NHMRC, 2011

Draft framework for climate change adaptation decision-making for

infrastructure, from DR AS 5334 (draft open for public comment)

Water quality risk management is aimed at

ensuring safe and reliable water supplies...

In a variable climate, these same objectives

will still need to be met. It is useful to frame

risks not so much as being from climate, but

to the water quality, public health and the

authority


Risk Management Step

(ISO 31000:2009)

Applied to Drinking Water Quality

Management

Considering a Changing Climate

Context setting Set water quality objectives and commit to

meeting them

The same objectives and commitments

are required

Risk identification Identify hazards, their sources, and

how/what influences their presence in the

system

Would projected changes in temperature,

rainfall, etc. impact on hazard source

types, quantities or propagation?

Risk analysis Determine how effectively current hazard

controls operate, and assess the risk

based on likelihoods and consequences

associated with customer exposure to

hazards

Would projected changes in temperature,

rainfall, etc. impact on the effectiveness or

overwhelmingly challenge the current

controls?

Risk evaluation Take stock of what is driving the

assessed risk: inherent conditions,

variability or information gaps/uncertainty?

Re-evaluate the level of risk that may

ensue under a changing climate: can the

system cope with the scenarios?

Risk treatment Operate, monitor and verify the controls.

Investigate uncertainties to better

understand risks

Accommodate or plan to develop

indicators of, watch for and respond to

the changes

Monitor and review Is the plan working? Were the tested scenarios relevant and

informative? Consider the latest science

and observations

Risk frameworks for water quality & climate management Describing the system, identifying hazards, and conceptualising risks to drinking-water quality


RISK = Consequence

Lik

elih

oo

d

x 1 2 3 4 5

1 Low Low Medium High High

2 Low Low Medium High Very High

3 Low Medium High Very High Very High

4 Medium High High Very High Very High

5 Medium High Very High Very High Very High

R2 = 0.1428

0

1

2

3

4

5

6

7

8

9

10

0.001 0.01 0.1 1 10 100

Average flowrate (m3/s)

oo

cysts

/ L

Baseflow

Runoff

Assessing and evaluating risks associated with meeting drinking water quality objectives – common approach

0

1

2

3

4

5

A B C n = 12 n = 12 n = 12

Tot. coliforms – measured log reductions

* Charts based on

data from real

drinking water

catchments and

treatment plants,

reported in Signor, R;

2007, Probabilistic

Microbial Risk

Assessment and its

management

implications for

Urban Water Supply

Systems

** Risk matrix

provided in the

2011Australian

Drinking Water

Guidelines

Evaluate risk based on effectiveness of all controls,

and further manage accordingly**

Understand the sources and drivers of hazard presence*

Understand control efficacy*

Evaluate risk based on understood impacts and

responses


RISK = Consequence

Lik

elih

oo

d

x 1 2 3 4 5






R2 = 0.1428

0

1

2

3

4

5

6

7

8

9

10

0.001 0.01 0.1 1 10 100

Average flowrate (m3/s)

oo

cysts

/ L

Baseflow

Runoff

Assessing risks associated with meeting drinking water quality objectives – example of re-evaluation for a changing climate

0

1

2

3

4

5

A B C n = 12 n = 12 n = 12

Tot. coliforms – measured log reductions

Understand the sources and drivers of hazard presence

Understand control efficacy

E.g. Disinfection efficacy is related to

water temperature (among other

things)

An average 5ºC increase in surface

water temperature can benefit

disinfection** (provided turbidity

stays low)

E.g. High rain/runoff events drive

pathogen loads entering the

reservoir

How might more frequent high

intensity runoff events challenge

the existing treatment and

controls?*

Re-evaluate under the described climate scenario:

• What’s the net change in risk?

• Would it become intolerable?

• What should be monitored to establish baselines

and extents of change over time?

• What can be done now to prepare should some

extent of climate change ensue?

RISK = Consequence

Lik

elih

oo

d

x 1 2 3 4 5






* NSW planning advice is to assume intensity of rainfall events with some average recurrence interval (e.g. 1 in 10, 1 in 100 years, etc.) estimated from Australian Rainfall &

Runoff (Engineers Australia, 1987) may increase by up to 30% (New South Wales Department of Environment, Climate Change and Water; 2007, New South Wales

Floodplain Risk Management Guideline, Residential Flood Damages). The chart demonstrates implications for 72-hour rainfall events for a coastal region near Sydney.

** Chart demonstrates improvement in disinfection by assuming a 5ºC increase in water temperature at a water treatment plant in South Australia (assuming all other

parameters remain constant). Figures derived by applying probabilistic modelling techniques and assuming continuous stirred tank reactor conditions.

Risk frameworks for water quality & climate management Raw water storage – responses to climate and variable inflow conditions (a storage in the Murrumbidgee catchment)

Challenges incorporating climate change

1. What climate scenarios and timeframes are relevant to use?

2. Understanding impacts of changes on water quality hazards, and

implications for likelihood and consequence

3. Timeframes for actions, decisions under uncertainty and continuous

change


1. What climate scenarios and timeframes are relevant to use?

• As drinking water quality compliance is assessed over annual

timeframes, use relevant, near-term projections (link to strategic

planning horizons)

• Useful to consider extreme changes for the purpose of overlay on

current assessment techniques: this can help to rule out non-

material risks…

… planning needs to balance scenario assumptions vs. response to

changes that arise over time


2. Understanding impacts of changes on water quality hazards, and

implications for likelihood and consequence:

• Workshops

• Models

• Scenario assessments

Further reading: Jones & Preston (2010); Adaptation and Risk Management, Climate Change Working Paper #15, Centre for Strategic Economic Studies, Melbourne

University. Accessed 12 July 2012 at http://www.cfses.com/documents/climate/15_Jones_&_Preston_Adaptation_and_Risk_Management_2010.pdf


3. Timeframes for actions, decisions under uncertainty and continuous

change:

• Develop monitoring informed by risk assessment to examine

baseline vs. future conditions

• Determine thresholds for action based on observations

• Plan now so to be able to act swiftly to changes or specific events if

necessary

Further reading: Fisk, G., & Kay, R, (2010) ‘Dealing with Uncertainty in Climate Change Adaptation Planning and Developing Triggers for Future Action’, Proceedings

Practical Responses to Climate Change National Conference, 29 Sep – 1 Oct 2010, Melbourne.

Framework for considering climate changes

Examples of practical adaptation

planning outcomes for water utilities:

• Model changes to pathogen catchment

loads under longer dry periods, higher

intensity rain conditions

• Establish water temperature and N.

Fowleri (a “warm water pathogen”)

monitoring program

• Assessment of treatment capability

against manganese, iron and

cyanobacteria spikes – develop

protocols for dealing with extreme

challenges

• Develop thresholds and monitor

organic content in raw water to

manage THMs

• Survey community tolerance and

resilience against water supply with

higher salt content

Conventional Water Quality Risk

Management Process

Incorporating climate change impacts Identify hazards

Assess RISK

Monitor, manage, review

Are aspects

of these

climate-

dependent?

Determine climate scenarios

(relate to planning horizons) Pathways - how do hazards

enter the system?

Controls – how are hazards

managed and how well?

Collate climate projection data

Re-assess RISK for relevant

hazards under different climate

scenarios

Determine planning priorities

Summary

1. Climate adaptation planning will be most effective when embedded into existing

organisational business and process

2. Risk management is prescribed for drinking-water quality and climate adaptation

planning; there’s an opportunity to embed them within core water planning activities

3. Continue to focus on water quality objectives as the basis of risk management; this will

contextualise/simplify the climate assessments

4. Scenario based assessments of impacts of climate change on source and treated water

quality are the most useful ways to identify possible future risks and to start planning for

them

5. Models and geographically downscaled climate projections will be needed to assist with

understanding future risks; pre-emptive monitoring and planning will keep authorities

ready to respond to changes

Footnote

This presentation is based on preliminary findings of a study to be reported in

Signor, R. S; 2012, ‘Drinking water quality risk management in Australia: accounting for a

variable climate’, in preparation

www.ghd.com

Documents

Water Quality Risk ManagementMicrobial Risk Assessment and its management implications for Urban Water Supply Systems ** Risk matrix provided in the 2011Australian Drinking Water Guidelines