&EPA
United States
Environmental Protection
Agency
CLIMATE READY
WATER UTILITIES
&EBV
Climate Resilience Evaluation and
Awareness Tool 2.0 Exercise with
Southern Nevada Water Authority
-------
&EPA
United States
Environmental Protection
Agency
EPA 817-S-13-002
January 2014
Climate Resilience Evaluation and
Awareness Tool 2.0 Exercise
with Southern Nevada Water Authority
CLIMATE READY
WATER UTILITIES
-------
GREAT Exercise with Southern Nevada Water Authority
TABLE OF CONTENTS
Table of Contents ii
Executive Summary 1
Background 2
Exercise Goals and Process 3
Progress and Accomplishments 4
Setup 4
Threats- Climate Scenarios 7
Assets 11
Risk Assessment 11
Adaptation Planning 14
Adaptation Package Design 14
Preliminary CREAT Results 15
Status and Lessons Learned 18
Current Status 18
Lessons Learned 19
Conclusion and Next Steps 20
Appendix A - Exercise Participants 21
Appendix B - Consequence Matrix 22
Appendix C - Climate Scenario Data 23
Appendix D - Scenarios with Threat Likelihoods 26
Appendix E - Baseline Analysis - Preliminary Results 27
Appendix F -Existing Adaptive Measures 30
Appendix G- Adaptation Packages 34
Appendix H - Recommendations for Future Tool Development and Training 35
Prepared for the U.S. Environmental Protection Agency under contract EP-C-10-060
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GREAT Exercise with Southern Nevada Water Authority
EXECUTIVE SUMMARY
The mission of the Southern Nevada Water Authority (SNWA) is to manage the region's water
resources and develop solutions that will ensure adequate future water supplies for the Las Vegas
Valley. Historically, drought and large population growth have stressed water management in
this region of the country. Recently, due largely to concerns about the additional impact of
climate change on current drought conditions, the SNWA participated in an exercise with the
U.S. Environmental Protection Agency (EPA) to demonstrate use of the recently released
Climate Resilience Evaluation and Awareness Tool (GREAT) version 2.0 by beginning an
assessment of overall risks to its system and identifying opportunities for adaptation. Through a
series of internal collaborations and webinars with EPA, SNWA participants discussed their
approach to a risk assessment and began collecting information related to available climate data,
anticipated climate change impacts and potentially vulnerable assets.
The exercise, which took place over approximately three months, culminated in a two-day in-
person exercise. SNWA participants considered impacts across three potential climate scenarios,
based on the projections provided within GREAT, in two future time periods (2035 and 2060).
Informed by these projections, participants defined numerous threats under each scenario and
time period and conducted a preliminary risk assessment for only the most relevant priority
assets. As part of this exercise, SNWA participants identified more than 60 current and potential
future actions to take in response to climate change.
Major accomplishments of the exercise included: obtaining a range of future climate projections
to consider, identification of priority threats and assets, completion of a preliminary risk
assessment and increased understanding and consensus building around key risk assessment
parameters (e.g., likelihood, consequences, climate data). Moving forward, SNWA is
considering using the consequence matrix and climate scenarios defined through this exercise
with an updated, more comprehensive database of its threats, assets and adaptive measures.
Based on the lessons learned during the exercise process, SNWA participants plan to revisit their
threat selection under each scenario, refine asset-threat pairing selections and preliminary risk
assessments and begin the design of packages to consider as possible adaptation plans. Another
benefit from this exercise was the opportunity to provide important feedback to EPA regarding
how utilities approach and use the tool.
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GREAT Exercise with Southern Nevada Water Authority
BACKGROUND
Southern Nevada Water Authority (SNWA) is a cooperative of seven member agencies founded
in 1991 with the collective mission to manage the region's water resources and develop solutions
that will ensure adequate future water supplies for the Las Vegas Valley. Drinking water is
primarily (nearly 90%) sourced from the Colorado River via Lake Mead and processed through
two water treatment plants to provide for Las Vegas valley residents and businesses.
Groundwater production provides additional water supply during summer months. Recent
extended drought has increased the challenge of continuing to provide a sustainable supply of
water. In response, over the past two decades, SNWA has implemented an effective water
resource plan1 focused on water resource diversification through demand management,
development of interim and in-state water resources, as well as efforts to address the uncertainty
of the ability of the Colorado River to meet future demand. In addition to the uncertainty of
future growth (and therefore demand forecasts) and existing drought challenges, SNWA must
cope with uncertainties related to how climate change may impact the supply of and demand for
water resources. To help assess future supply and demand imbalances for the region as well as
potential solutions to those imbalances, the US Bureau of Reclamation, in collaboration with
Basin States2, supported and participated in the Colorado River Basin Water Supply and Demand
Study3 from 2010 to 2012. The study considered four Colorado River water supply scenarios that
took into account two major uncertainties: changes in stream flow variability and changes in
climate variability and trends. When considered as averages across multiple supply and demand
scenarios for the region, the study found a median supply and demand imbalance of 3.2 million
acre feet by 2060. In the past, Colorado River droughts and subsequent reductions in water
supply have been largely dealt with by tapping in to reservoir storage supplies. However, from
1999-2008, average inflow from the Colorado River was 66% of normal resulting in storage of
only 52% of total capacity in the primary reservoirs4. With reservoir levels continuing to drop
since 2008 due to drought conditions, SNWA has pursued multiple strategies to manage water
resources including enacting drought contingency plans, including development of additional
water resources and increased conservation measures. Due to the concern of continued drought
and potential exacerbation of water management issues by climate change, SNWA is taking
additional action to assess and respond to potential system vulnerabilities.
1 Southern Nevada Water Authority Water Resource Plan online at http://www.snwa.com/ws/resource_plan.html.
2 Basin States are Wyoming, Colorado, Utah, Nevada, New Mexico, Arizona and California.
3 Hereafter referred to as "Basin Study" in this report. Information and links to study documents can be found at
http://www.usbr.gov/lc/region/programs/crbstudy.html.
4 Lake Mead and Lake Powell, as described in 2009 Southern Nevada Water Authority Water Resource Plan.
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GREAT Exercise with Southern Nevada Water Authority
EPA's Climate Resilience Evaluation and Awareness Tool (GREAT) version 2.0 was developed
to help water and wastewater utilities evaluate and assess the potential impacts of climate change
on utility system assets. GREAT 2.0 includes three climate scenarios for every location in the
U.S., based on available climate projections to assist utilities in scenario planning to support
robust decision making. By guiding users through a decision-making framework, GREAT helps
utilities understand risks and assess opportunities to reduce risks from future climate impacts.
The GREAT framework is flexible and can support utilities at any stage in the risk assessment
process, from those considering only a few priority assets to those pursuing a more complex
assessment of assets and threats across a range of climate scenarios and time periods.
EXERCISE GOALS AND PROCESS
SNWA partnered with EPA in an exercise to conduct a full risk assessment using GREAT 2.0 to
determine the potential impacts of climate change on its operations and identify adjustments to
management of future water supplies. Specific exercise goals included using GREAT to:
• Obtain a range of future climate projections for the Las Vegas Valley for both short- and
long-term time periods (i.e., 2035 and 2060)
• Identify the assets most vulnerable to weather and climate-related threats, based on
climate projections
• Develop cost-effective adaptation strategies to minimize threats using the CREAT-
provided risk reduction unit (RRU) metric and demonstrate resilience (or lack of
resilience) to future climate threats both with and without adaptation.
• Familiarize staff with the climate change risk assessment process and develop a database
file including SNWA assets, threats and adaptive measures for use in future assessment
iterations.
• Develop a report of process and findings.
EPA introduced participants to the GREAT software and risk assessment process (Figure 1) over
a series of two webinars. Between webinars, SNWA participants collaborated through subgroup
meetings and used Excel spreadsheets to facilitate data collection. Ongoing productive
discussions constantly refined the data being input. The exercise culminated in a two-day in-
person event at SNWA which provided an opportunity for participants from SNWA and the Las
Vegas Valley Water District (LVVWD) to conduct assessments as a group, build and discuss
potential adaptation packages and identify a path forward for future work (Appendix A).
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GREAT Exercise with Southern Nevada Water Authority
Local Historical & Projected Climate Data
-Temperature
-Precipitation
-Intense Precipitation
-Sea-level rise
Regional Projected Climate Information
Resilience
Analysis
Results
and
Reports
Adaptive
Measures
Adaptation
Planning
Figure 1. CREAT process
PROGRESS AND ACCOMPLISHMENTS
During this exercise, SNWA completed a preliminary risk assessment to assist with climate
change and adaptation planning. CREAT provided relevant climate data and a framework that
facilitated discussion and assessment of specific threats on priority assets. Participants gained a
more thorough understanding of the climate data, the risk assessment process and how to think
strategically about adaptation despite an uncertain future. The first three steps of the CREAT
process - Setup, Threats and Assets - provided an important opportunity for SNWA to collect
and organize relevant data and make key decisions related to its analysis parameters including
the use of climate scenarios. To date, specific accomplishments include: identification of analysis
parameters, selection of climate data to use in analyses, identification of priority threats,
identification of vulnerable assets, completion of baseline and resilience analyses for priority
asset/threat pairs, documentation of existing and potential adaptive measures and preliminary
design of adaptation packages.
SETUP
The Setup step of CREAT provides users with the opportunity to catalog basic utility
information and to customize their assessment in terms of locations considered and desired
analysis parameters. CREAT allows users to select between one and four locations for analysis.
The location feature helps users understand the scale at which climate projection data are being
provided before beginning assessments and can help determine where impacts should be
assessed. The ability to utilize climate projection data from multiple locations is particularly
important for utilities that have geographically widespread assets and for those that depend on
large watersheds for system supply (Figure 2).
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GREAT Exercise with Southern Nevada Water Authority
a
CD
North Las
Vegas
®
'
.
Lake Mead
National
Recreation Are;
Figure 2. Map of SNWA's primary operating area with overlay of CREAT-provided
grid cells at 0.5 by 0.5 degrees, also the resolution of climate data.
GREAT users can select from pre-loaded NOAA weather stations or provide their own data for
historical annual and monthly temperature and precipitation. During early discussions, SNWA
participants considered four separate locations representing strategic areas of both lower and
upper portions of the watershed (e.g., McCarran Airport; Las Vegas Wash; Ely, NV; and
Fontenelle Dam). However, the group decided to focus on the McCarran Airport location which
is closest to its customer base and drinking water facilities and is the site SNWA relies on for
weather data. One parameter, daily maximum temperature, is an important metric used by
SNWA for planning but is not provided in GREAT and therefore wasn't used as part of this
assessment.
There were also slight differences between the historical data provided by GREAT and that
typically used by SNWA from the McCarran station. These minor differences result from the
fact that historical average data in GREAT are based on multi-station averages by grid cell as
provided in the Parameter-elevation Regressions on Independent Slopes Model5 (PRISM),
whereas SNWA historical data is sourced directly from one individual weather station. In
addition, the historical intense precipitation data are based on a curve fit to a Generalized
Extreme Value curve. Differences between CREAT-provided and other data sets are likely due
to methodological differences (e.g., rules for excluding data outliers, years included in the data
set and curve fit method). After reviewing the CREAT-provided data and comparing to its own
data, SNWA opted to use the data provided from the McCarran station. Within GREAT,
' The PRISM Climate Group website is http://www.prism.oregonstate.edu/.
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GREAT Exercise with Southern Nevada Water Authority
selection of historical data is important because this designates the data set to which changes in
climate (projection deltas) will be applied.
In addition to accommodating utility weather and climate data sets, GREAT also gives users
flexibility in how they may approach the two standard components of risk: likelihood and
consequence. These decisions are made during Setup and applied uniformly to all subsequent
analyses. For likelihood, there are two options. Users can choose to assess the likelihood of
various climate-related threats on a four-point qualitative scale (from Low to Very High) or they
can simply assess each threat as if it would occur by using conditional likelihood, which sets all
likelihood assessments to Very High (i.e., providing a 'what-if approach). It is important to note
that within GREAT likelihood refers specifically to the likelihood of a threat occurring given a
certain climate scenario (e.g., likelihood of lower lake levels assuming the Hot and Dry scenario
occurs). The likelihood assessment does not imply that users can assess how likely climate is to
change, rather that under specific projected conditions, they can assess the likelihood of
particular impacts or threats (e.g., if temperature rises 3 degrees and precipitation drops by 5%,
how might this impact source water availability). The ability to assess threat likelihood is greatly
improved when threats are explicitly and quantitatively defined. In some cases, this requires the
help of tools and datasets outside of the GREAT process. During initial discussions, SNWA
elected to consider the likelihood parameter within its risk assessment. However, during the in-
person exercise SNWA also ran a sensitivity analysis by switching the likelihood setting to
conditional and reviewing how this changed overall risk results.
The review and refinement of consequence categories and weightings is also an important
determination within Setup that impacts analysis results. GREAT provides five categories
representing the different types of consequences a utility might face from climate-related
impacts. These categories include: Utility Business Impacts, Utility Operational/Equipment
impacts, Source/Receiving Water Impacts, Environmental Impacts and Community/Public
Health Impact (Figure 3). Within the tool, users can modify these categories, their definitions
and the weights assigned to them. Category definitions are significant because they are used to
systematically assess consequences for all threats on all assets. Following discussion, SNWA
refined its consequence categories; those related to business, source water, and community health
impacts were defined in terms of capital investment costs, water shortage duration and loss of
life, respectively. Quantification of consequence levels for equipment impacts was based on
insurance deductibles (Appendix B).
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GREAT Exercise with Southern Nevada Water Authority
Utility Business Impacts
Revenue or operating
income loss evaluated in
terms of the magnitude
and recurrence of service
interruptions.
Utility
Operational/Equipment
Costs of rep lacing the
service equivalent
provided by a utility or
piece of equipment
evaluated in terms of the
magnitude of damage
(minimal, minor.
Source/Receiving Water
Impacts
Environmental Impacts
Degradation or loss of Evaluated in terms of
water quality and/or
quantity evaluated in
terms of the recurrence."
(minimal, temporary,
seasonal or episodic.
loss (aside from source
water or other assets) and
compliance with
environmental regulations
(minimal, short term.
Community/Work Force
Health Impact
Evaluated in terms of the
duration (short or long-
term) and extent (minimal,
minor, localized, or
widespread)
Weight
Figure 3. Consequence categories and definitions as provided within GREAT.
In addition, the option to weight different categories equally, variably or to use the highest-level
consequence category for each asset/threat pair being analyzed gives utilities the opportunity to
further customize their parameters. Equal weighting essentially implies that the utility views
consequences in all five categories as equally debilitating to their environmental and public
health missions; whereas, weighting some categories more heavily than others reflects where a
utility is unwilling to accept losses. In contrast, those categories weighted less heavily reflect
areas where a utility is willing to accept some losses. Within its analysis, SNWA chose to accept
the default of equal weighting across consequence categories. However, as with likelihood, they
were curious about the sensitivity of results to this setting and they explored the effect of using
the highest weight setting for consequences on their analysis results.
THREATS - CLIMATE SCENARIOS
GREAT allows users to consider threats to utility assets under different climate scenarios as part
of the risk assessment process. Within GREAT, scenarios are defined as projected changes in
climate with respect to average conditions (temperature and precipitation), extreme events
(intense precipitation) and sea-level rise (not applicable to SNWA analysis). For each user-
defined location, GREAT provides three scenarios that represent a range of potential future
climate conditions. The method used by GREAT for climate model selection is described in the
GREAT v2.0 Methodology Guide, available in the software downloaded from the EPA GREAT
website6. Climate model results are plotted in terms of their projected average annual change in
temperature and precipitation for each location in the 2060 time period (Figure 4).
' http ://water. epa. gov/infrastructure/watersecuritv/climate/creat. cfm
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GREAT Exercise with Southern Nevada Water Authority
I
• 4.7
fMRf]
|MIRO|
4.3 4.6
Temp Change (F)
Figure 4. Scatter plot showing the range of model projections (squares with model
name in each flag) for the SNWA McCarran airport location in terms of changes in
temperature (in degrees Fahrenheit) and precipitation (as percentage) relative to
today's conditions. Green circles indicate statistical targets (with temperature and
precipitation percentiles in each flag), while blue squares show selected model
projections for this location.
GREAT calculates statistical targets based on the distribution of projected changes in
temperature and precipitation (95th percentile temperature /5th percentile precipitation, 50/50 and
5/95) and then selects the model closest to these targets. These models represent a future that
relative to today tends to look hot and dry (i.e., increase in temperature, decrease or minimal
increase in precipitation), warm and wet (i.e., some increase in temperature, but greater increase
in precipitation) and a central model projection between these two outer bounds. These projected
conditions are based on the projected changes applied to the historical data provided by exercise
participants (Table 1). This method of applying model projected changes to user-provided
historical conditions gives users a consistent comparison between current and projected
conditions founded in their experience and informed by climate model data.
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GREAT Exercise with Southern Nevada Water Authority
Table 1. SNWA defined historical data for defining scenarios.
Annual
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
Average
Temp (F)
68.10
47.00
52.20
58.30
66.00
75.40
85.60
91.20
89.30
81.30
68.70
55.00
47.00
Total Precip
(inches)
4.49
0.59
0.69
0.59
0.15
0.24
0.08
0.44
0.45
0.31
0.24
0.31
0.40
Total precipitation (in) during 24-hour event
5-year
1.18
0.75
0.55
0.79
0.75
10-year
1.42
0.91
0.79
1.22
0.98
15-year
1.54
0.98
0.91
1.54
1.1
30-year
1.73
1.14
1.18
2.17
1.3
50-year
1.89
1.26
1.38
2.8
1.46
100-year
2.09
1.38
1.73
3.98
1.69
The purpose of providing multiple scenarios within GREAT is to help users grapple with the
uncertainty inherent in all climate projections. Considering the range of possible conditions often
facilitates identification of worst-case scenarios and prioritization of assets and threats that
should be examined in greater detail. In regards to their risk assessment, SNWA wanted to
consider multiple scenarios and choose to adopt the GREAT-provided Hot and Dry, Central and
Warm and Wet scenarios within their analysis file. The decision to adopt the GREAT data, even
though SNWA also had data available from the Basin Study, was based on the fact that both use
the same available climate models in their analysis7. Because of the high percentage of overlap,
the adoption of GREAT data was deemed the most efficient path forward. Within each scenario,
users can consider impacts in both mid- and long-term time periods. Specifically, GREAT
provided SNWA with projected conditions for 30-year periods centered on 2035 and 2060.
The temperature and precipitation data used as the three scenarios in GREAT are provided in
Appendix C. Going forward, SNWA may opt to switch historical data sets to adjust the baseline
climate while still using the CREAT-provided scenarios. The average condition data was based
on data collected and used by SNWA. The intense precipitation data provided in GREAT for the
same station (COOP 264436) was adopted as part of the historical climate data set.
Under each climate scenario, SNWA defined more than a dozen possible threats for analysis
(Table 2). Many of the climate-related threats of concern for SNWA are those occurring as a
7 Data from World Climate Research Programme (WCRP) Coupled Model Intercomparison Project phase 3
(CMIP3) multi-model dataset. Available online at http://gdo-dcp.ucllnl.org/downscaled_cmip3_projections/
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GREAT Exercise with Southern Nevada Water Authority
result of climate conditions outside the service area, specifically drought in the Colorado River
Basin which largely controls Lake Mead reservoir levels and changes in reservoir water quality
(e.g., concentrations of total dissolved solids, bromide and total organic carbon). Defining threats
within GREAT involved the identification of specific parameters such as the magnitude of
concern, changes through time and an assessment of the likelihood of each threat under each
scenario (Appendix D).
Table 2. SNWA-defined threats for application in GREAT risk assessment. Threats
with * were part of priority analysis.
Threat
* Low Lake
* Extreme Low
Lake
* Warm H2O
H2O Demand
H2O Quality
Pwr Grid
Pest
Fire
Flood
GW recharge
Runoff time
Snow
Wetlands
High Temps
High H2O Cost
Unhealthy
Environment
Living Cost
Description
1075-1000 ft are trigger levels to shortage (13,000 to 20,000 acre-feet per year) on CRB
Note: Below elevation 1025, shortages may exceed 20,000 acre-feet per year.
<1000 ft amsl - Loss of capacity to draw water
Warm water inflow and/or warm water in distribution system
Changing evaporative demand for residential/commercial landscapes may cause
consumptive use to rise. Greater system demand. Rising maximum daily temperatures,
increasing number of extreme heat days may impact peak demand during summer months.
Lengthening of the (Landscape) growing season is expected.
Separate from warm water to include changing concentrations of TDS, Bromide and TOC
The number of cooling degree days are expected to rise (and the number of heating degree
days will fall), causing increased strain on the power grid.
Invasive species
Rise in wildfires
Extreme flooding
Reduced groundwater recharge
Change in timing of runoff (Distribution volume and temperature challenges)
Reduced winter snowpack accumulation
Loss of wetlands
Higher working temperatures
Increasing cost of water
Unhealthy environment (air quality i.e. high ozone or high particulate levels)
Higher cost of living (power, gas, food, medical care, etc.)
During the exercise, SNWA focused on the scenario of greatest concern given recent drought
trends, the Hot and Dry Scenario. Due to the critical nature of drought, participants opted to
include both lower lake levels (1000-1075 ft), and extreme lower lake levels (<1000 ft) as threats
to the Lake Mead water resource. Instead of basing the definition of these threats on the CREAT-
provided climate scenarios, SNWA used information available from the Basin Study on
projected changes in lake levels associated with similar projected climate scenarios. Although
low lake levels have historically resulted in water quality challenges, the warmer water threat
was explored within the assessment to a limited extent because of the lack of supporting
quantitative data available during the exercise.
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GREAT Exercise with Southern Nevada Water Authority
ASSETS
SNWA participants cataloged numerous assets related to their water and environmental
resources, infrastructure and personnel that might be impacted by climate-related threats within
GREAT. However, during the discussion of scenarios and threats, they recognized the need to
keep the number of analyses within scope and were able to exclude cataloged assets from
analysis. Assets were prioritized based on having three characteristics, 1) the asset is critical to
achieve SNWA's mission, 2) the asset has been sensitive to climate parameters historically, and
3) there are potential adaptation options available to SNWA that could minimize risk. Priority
assets were easily identified with the priority threats of reduced lake levels and warmer water.
Furthermore, SNWA prioritized three asset/threat pairs for assessment to understand the impact
of lower lake levels on the Lake Mead asset and warmer water on the water treatment system
asset.
RISK ASSESSMENT
In contrast to the previous steps in the GREAT process, the risk assessment steps guide users
through an assessment process for each asset and threat. These assessment results provide the
data needed to gauge effectiveness of adaptation and develop plans. The results presented within
this section of the report are demonstrative of the tool process and should not be taken as a final
risk assessment for SNWA assets.
During the second webinar, the Baseline Analysis steps in GREAT were conducted using the
asset/threat pair of Lake Mead intakes and lower lake levels. In GREAT, Baseline Analysis
consists of three steps:
(1) Identify existing adaptive measures - These measures include any actions or
infrastructure planned or currently being used to reduce the consequences of a threat on
an asset. For the example, SNWA indicated that it is already conducting demand
management practices and constructing a new intake (by 2014); both of which were
included as existing measures.
(2) Assess consequences - For each asset/threat pair and time period, the severity of impact
for each of the consequence categories can then be assessed. The group assessed the
overall impact as medium, but did not resolve the level by category. The levels for each
category were set to medium for demonstration purposes with the agreement to revisit
later.
(3) Review results - In the final step of baseline; GREAT provides a summary of results for
the impacts of lower lake levels on the Lake Mead asset. Results display the overall
qualitative metrics for likelihood, if applicable, and consequence. All steps provide
optional comment fields to capture any assumptions or rationale used during assessment.
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GREAT Exercise with Southern Nevada Water Authority
Similarly, a preview of the Resilience Analysis steps in GREAT was provided with the
asset/threat pair of Lake Mead intakes and lower lake levels. Resilience Analysis in GREAT
consists of four steps:
(1) Identify potential adaptive measures - Unlike Baseline Analysis, potential measures are
defined as any additional actions that are possible to reduce the consequences of a threat
on an asset. In lieu of any specific measures ready for discussion, the concept of a
hypothetical 'Healthy-sized Water Resource Acquisition' was used as a placeholder.
(2) Adjust consequences - The assessment of consequences in Resilience Analysis is an
adjustment of the baseline consequences to a new level based on any changes once
potential measures are implemented. This assessment is a "what-if' assessment of the
gains attributable to adaptation. In this case, consequences from lower lake levels would
decrease with the addition of the hypothetical water resource acquisition.
(3) Assign adaptive measure contributions - Each potential measure used receives a fraction
of the 'credit' for assessed reductions consequences following implementation. Some
measures may provide a larger gain in resilience than others and providing these fractions
better informs decisions when considering performance of adaptive measures across
several assets and threats. For this example, the single measure used is assigned 100%
contribution.
(4) Review results - As in Baseline Analysis, GREAT provides a summary of all risk
assessment results for this asset/threat pair.
The baseline analysis results give a snapshot of projected risks in future time periods (2035 and
2060) if SNWA continues business as usual, but takes no additional action to adapt to climate
change. The majority of the work related to SNWA assessments on priority asset/threat pairs was
conducted during the in-person portion of the exercise (Appendix E) which allowed for group
discussion and consensus building related to consequence assessment and adaptive measure
contribution. As part of the work between events, SNWA completed a baseline analysis for each
priority asset/threat pair in both time periods of the Hot and Dry scenario. Results are displayed
for equal weighting of consequence categories (Figure 5).
As part of the baseline analysis process, participants brainstormed those utility practices that
could be considered adaptive measures. Collectively, participants identified more than 60
existing and potential adaptive measures for potential use in its assessments (Appendix F). The
group used an iterative process to populate information (i.e., descriptions, relevant threats and
costs) with respect to these adaptive measures within GREAT. Qualitative or quantitative cost
information for both initial capital and operation and maintenance were provided to the extent
possible.
In the initial baseline analysis results, many threats were assessed as an overall low risk. Upon
re-visiting these assessments, participants noted that the low risks were a result of the
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GREAT Exercise with Southern Nevada Water Authority
consequence weighting method which was set to equal across all categories. For example, for the
extreme low lake levels threat, even though the consequence assessment for the source/receiving
water category was rated high, the low consequence rating of the four other consequence
categories produced an overall consequence assessment of low. To better understand how
consequence weighting methods impacted results, SNWA produced multiple versions of its
analysis results using different settings. From this point on during the exercise, the highest-level
setting was used to reveal the overall higher levels of consequence assessed for each category.
Infrastructure
B M Intakes and raw water conveyance system
Altered water quality fLISI)
Changes in residential use (L1S1)
Invasive species (L1S1)
Lower lake and reservoir levels (L1S1)
Poor Power Grid Performance (LI SI)
Warmer Water Temperatures (L1S1)
B!X1 LWWD Distribution Grid and Conveyance
Changes in residential use (L1S1)
Extreme low lake level (US1)
High flow events (L1S1)
Lower lake and reservoir levels (L1S1)
Poor Power Grid Performance (L1S1)
Warmer Water Temperatures (L1S1)
B]M SNWA Water Treatment Systems
Altered water quality (L2S1)
Changes in residential use (L1S1)
Extreme low lake level (L1S1)
High flow events (L1S1)
Invasive species (L1S1)
Lower lake and reservoir levels (L1S1)
Poor Power Grid Performance (L1S1)
Warmer Water Temperatures (L1S1)
B Kl Natural Resources
B M Surf ace water
El W Lake Mead
Extreme low lake level (L1S1)
Lower lake and reservoir levels (L1S1)
2035 '(
2035
2035
2035
2035
2035
2035
2035 '
2035
2035
2035
2035
2035
2035
2035 i
2035
2035
2035
2035 '
2035 ''
' 2060
2060
2060
2060
2060
2060
2060
2060
2060
2060
2060
2060
2060
2060
2060
2060
2060
2060
2060
2060
'i 2035 ( 2060
'4 2035 '4 2060
Figure 5. Preliminary baseline analysis results for all asset/threat pairs in the Hot
and Dry scenario using the weighted sum method of consequence assignment.
Additional assessment during the in-person exercise focused on resilience analysis for priority
asset/threat pairs in the Hot and Dry scenario. Specifically, participants discussed and assessed
adaptation options to reduce the threat of extreme low lake levels on Lake Mead and the threat of
warmer water temperatures for their water treatment process. To address the issue of drought-
induced extreme low lake levels, participants proposed a variety of adaptive measures including:
using groundwater to augment supplies, optimizing use of the third intake, strengthening existing
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GREAT Exercise with Southern Nevada Water Authority
measures (demand management, leakage reduction, drought contingency plan), maintenance of
interim supplies (bank recovery and/or ICS), re-allocation (as designated in the Colorado River
Basin Study report) as well as modeling supply and demand and monitoring weather. With these
options in place, the group adjusted consequences for the source/receiving water category from
high to low (i.e., seasonal or episodic impacts would be reduced to minimal impacts).
The rationale for the contribution of each adaptive measure to the overall reduction in risk was
based on the ability of each to make up the resource lost with groundwater resources and interim
supplies contributing the most (>50%). The group also elected to include access to the Las Vegas
Valley groundwater bank as a short-term bridging resource (a potential measure), but set its risk
reduction contribution to zero percent to reflect the limited amount of water available for
withdrawal in any given year. Inclusion of this measure within the analysis was for the purpose
of keeping track of all options to respond to drought-induced lower lake levels.
The group also discussed and assessed options to reduce the consequences of warmer water
temperatures on its treatment system. To address the medium level risk for 2035 (as determined
in the Baseline Analysis), participants proposed well-use optimization and accessing
groundwater supplies as bridging efforts. Research to help identify critical factors would be low-
cost and could be pursued to help refine existing efforts. Following these bridging efforts, the
group proposed that altering treatment by increasing the use of air stripping would be pursued
until addition of chloramination became more economical. Further alteration of treatment
processes, such as through the installation of influent cooling systems and use of advanced
treatment (i.e., reverse osmosis or microfiltration) would only be considered as a last resort.
Other last resort options included engaging in discussions of regulatory flexibility and point-of-
use treatment. With this full suite of measures in place, the group assessed that risks would drop
to a low level of consequence. Although resilience analyses were only completed for a few
conditions, the process was instructive and the preliminary results are presented in Figure 6.
Participants noticed that although the first assessment was rather difficult, subsequent
assessments became easier as the group increased its comfort and familiarity with the process.
ADAPTATION PLANNING
AD APIA TION PA CKA GE DESIGN
Adaptation planning refers to the process of considering potential impacts from climate change
and developing strategies to address those impacts. Comparison of different options includes
taking a critical look at costs, the time required to implement different measures and an
assessment of how effective these options may be in mitigating consequences. Using the results
of the baseline and resilience analyses, the tool calculates risk metrics (i.e., risk reduction units
or RRUs).The comparison of different packages of adaptive measures is done within the
Adaptation Planning tab. Adaptation packages in GREAT do not necessarily need to be discrete
as long as users understand how to compare them. For example, package design may reflect
funding availability, represent a tiered approach to adaptation or focus on specific portions of the
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GREAT Exercise with Southern Nevada Water Authority
system. SNWA participants elected to pursue the development of packages based on 'trigger
points' which align with their general approach to planning (i.e., pursue lower cost options first
and consider additional actions when certain thresholds or trigger events are reached).
McCarran International Airport (LI) Location 2 (12) | Location 3 (13) | Location 4 (14)
Asset/Threat
* 'Hot and dry model projection (SI)
BjKflnfrastructure
BjNllntakes and raw water conveyance system
Altered water quality (L1S1)
Changes in residential use fLISI)
Invasive species (L1S1)
Lower lake and reservoir levels fLISI)
Poor Power Grid Performance (L1S1)
Warmer Water Temperatures fLISI)
E)Wl-WWD Distribution Grid and Conveyance
Changes in residential use (L1S1)
Extreme low lake level (L1S1)
High flow events (L1S1)
Lower lake and reservoir levels fLISI)
Poor Power Grid Performance (L1S1)
Warmer Water Temperatures fLISI)
B|^SNWA Water Treatment Systems
Altered water quality (L1S1)
Changes in residential use fLISI)
Extreme low lake level (L1S1)
High flow events (L1S1)
Invasive species fLISI)
Lower lake and reservoir levels (L1S1)
Poor Power Grid Performance fLISI)
Warmer Water Temperatures (L2S1)
BiN"Natural Resources
BlN* Surface water
2035
2060
2035
2035
2035
1*2035
12035
2035
2035
2035
2035
|'2035
2035
•'2035
2035
2035
2035
2035
2035
2035
2035
>'2035
4 2060
4 2O60
2060
'2050
4 2050
2060
4 2060
2060
4 2060
'2060
4 2060
'2060
2O60
4 2060
( 2060
2060
2060
2060
| 2060
•'2060
Extreme low lake level (U.S1)
Lower lake and reservoir levels (L1S1)
i |'2O35 i tr'2060
2060
Figure 6. Refined preliminary baseline analysis results (using highest level
consequence method) and resilience analysis results for priority asset/threat pairs.
SNWA designed five adaptation packages to address two main threats: challenges related to
water quality and challenges related to temperature management in the distribution system. Four
of these packages included short- and long-term solutions to these respective issues, while the
fifth package included last resort measures. The types of triggers for each package were
identified, although the exact thresholds are yet to be determined (Appendix G).
PRELIMINARY GREAT RESULTS
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GREAT Exercise with Southern Nevada Water Authority
Assessment results are presented in GREAT through three types of data displays within the
Results tab. The results summary screen shows an overview of progress within the tool by
displaying a risk profile and a risk index. The risk profile is a series of stacked bars that display
baseline and resilience results in each defined scenario. The risk index graph shows two overlaid
bars that illustrate how much resilience is gained in each scenario via the difference between
baseline and resilience results. Displays can be modified to show results from select locations,
time periods or adaptation packages.
Following the conclusion of the in-person exercise, preliminary results indicated that SNWA
may experience a broad range of climate impacts with the most severe consequences occurring in
the Hot and Dry scenario. Because assessments to date have focused on prioritized asset/threat
pairs in a single scenario, it is difficult to assess the potential for adaptation (the ability to gain
resilience through remedial actions) across scenarios. Although preliminary baseline analyses
were conducted for all three scenarios, SNWA may choose to revisit analyses conducted in the
Central and Warm and Wet scenarios at a later date to ensure that the thought process and
assumptions are consistent with those for the Hot and Dry scenario.
In this particular case, the results summary screen may be less instructive when the weighted
sum method is used because of the high number of asset/threat pairs that have low baseline
consequence results. This situation provides few opportunities for users to assess improvement
during the resilience analysis. In order to reveal assessments where higher consequence levels
were assigned to individual categories, you can either choose to weight certain categories at a
higher percentage or select the highest-level option during Setup. Switching to highest-level
option provided more results with high and very high consequences to address through
implementation of adaptive measures during resilience analysis (Figure 7).
Baseline/Resilience Consequence Risk Profile
Figure 7. The SNWA risk profile under highest level consequence method shows
improvement going from Baseline to Resilience, illustrated by a greater number of
asset/threat pairs with low risk (green) and fewer with high and medium risk
(orange and yellow) for Scenario 1. Scenarios 2 and 3 show inconsistent results
because no resilience analyses were conducted.
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GREAT Exercise with Southern Nevada Water Authority
The second type of result display, the risk index graph, currently provides minimal information
because not all asset threat pairs with a baseline analysis have a corresponding resilience analysis
and therefore the RRU values provide an incomplete representation of potential resilience
gained. The power of this graphic will be more apparent once the full risk assessment is
complete and it can be used to help understand the relative risks under different climate scenarios
and the potential to reduce risks through adaptation (Figure 8).
Risk Index by Scenario
•o
c
S4
S5
Figure 8. The SNWA risk index by scenario (SI through S5 on axis) shows some
potential for reducing overall risk levels (blue bars) through adaptation for each
scenario. Additional resilience (inset white bar in SI) will become apparent upon
completion of the remaining assessments and any refinement of existing
assessments.
Results for each analysis are also presented on the risk matrix drill down tab. This tab includes a
series of 4-by-4 risk matrices which display the number of asset/threat pairs in each combination
of likelihood (from low to very high) and consequence (from low to very high). Comparing the
numbers between baseline and resilience analyses within each scenario, it is desirable to see
numbers shift from right to left, indicating a reduction in the consequences due to the
implementation of adaptive measures. For climate risks, it is very unlikely that users will be able
to locally influence the likelihood factor for risk and therefore there is no shift anticipated from
top to bottom within the matrices. Preliminary SNWA results show similar patterns in baseline
results across scenarios, with a clustering of assessments of high likelihood and medium
consequence. Available results in the resilience matrices indicate a shift towards lower
consequences (Figure 9). However, the main purpose of this screen is to compare the movement
between baseline and resilience within individual scenarios, which is difficult to do given the
incomplete assessment status and without knowing which specific asset threat pairs fall into each
category and comparing them one to one. Once all assessments are complete, it will be much
easier to detect patterns and identify solutions that are effective across scenarios.
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GREAT Exercise with Southern Nevada Water Authority
Scenario 1
(Hot and dry mode
projection)
Scenario 2
(Central model
projection)
Scenario 3
(Warm and wet
mode) projection)
Baseline
Resilience
Figure 9. Preliminary risk matrices under highest-level consequence weighting
method. The presence of multiple asset threat pairs in the very high category for
consequences is the result of just one category being assessed as a very high
consequence. These results do not reflect the final risk assessment and are meant to
demonstrate the display within GREAT.
STATUS AND LESSONS LEARNED
CURRENT STATUS
The majority of exercise goals have been accomplished, including the following.
• SNWA obtained a range of future climate projections for the Las Vegas area for both
mid- and long-term time periods (i.e., 2035 and 2060).
• SNWA identified the assets most vulnerable to weather- and climate-related threats based
on climate projections.
• SNWA partially completed the third goal by conducting resilience analyses for two
asset/threat pairs; for each pair, participants developed cost-effective adaptation strategies
to minimize threats using the CREAT-provided risk reduction unit (RRU) metric and
demonstrated resilience (or lack of resilience) to future climate threats both with and
without adaptation.
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GREAT Exercise with Southern Nevada Water Authority
• SNWA participants have a good understanding of the risk assessment process and have
developed a GREAT database file that includes SNWA assets, threats and adaptive
measures that can be used for reference and to help support future assessment iterations.
In addition to these goals, SNWA completed a preliminary assessment of risks from climate
impacts based on local climate projections, as well as asset and threat prioritization (an important
early step in the GREAT process). SNWA also accomplished consensus building among its
diverse group of participants regarding consequence categories, use of climate data, contribution
of adaptive measures, prioritization of threats and assets and discussion of adaptation planning.
All of these decisions are critical parts of the GREAT process, and building consensus on these
decisions gives greater weight to and a sense of wider ownership of the results of the analyses.
LESSONS LEARNED
Throughout the exercise, participants developed an understanding of how to use GREAT to
conduct a risk assessment and identified key questions to address in future planning sessions.
During this process, some of the more challenging steps within the GREAT process provided an
opportunity for participants to question existing assumptions, refine use of terminology,
understand the differences between different analysis parameters in GREAT (e.g., likelihood and
consequence weighting) and think critically about the definition of threats and the assessment of
consequences from those threats. Participants provided important feedback regarding their
process and recommendations for future GREAT users including the following:
• Risk assessments can be conducted in many different ways. It is important that a utility
have a clear sense of its goals and how to accomplish them within the software and that
the utility reference the appropriate worksheets and other materials to aid in key decisions
related to data population. It is generally easier to start small and build out than to start
with a large data set and narrow it down.
• Creating scenarios and defining meaningful threats under each (e.g. details about the
magnitude or frequency of a threat) is a necessary precursor to the risk assessment
process. Additionally, utilities may want to identify other tools and models that can
inform the GREAT analysis process (e.g., hydrologic or water quality models that have
temperature or precipitation as input parameters).
• Users may need to consider the time necessary to implement adaptive measures (planning
versus implementation).
• Within risk assessment, the adaptive measure contribution step was challenging.
Specifically, users need guidance on how to capture high-cost or last-resort options, how
to incorporate the likelihood of adaptive measures into this decision, how co-benefits are
captured within the two and feel comfortable deciding when to lump and when to split
adaptive measures.
• In some cases, users may need to consider unintended consequences of adaptation
packages (impacts and consequences that are not covered by external costs).
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GREAT Exercise with Southern Nevada Water Authority
• Additional suggestions related to future tool development and training exercises are
cataloged in Appendix H.
CONCLUSION AND NEXT STEPS
SNWA described its progress to date as 'a good first cut general assessment to be followed up
with a more comprehensive assessment'. SNWA foresees the potential to use additional
locations if the assessment extends to its other water purveyors and possibly to the flood control
district. In the short-term, SNWA plans to refine its approach to the use of scenarios by:
• Revisiting threat selection and definition for each scenario and revisiting which assets are
designated as vulnerable or as priorities under these conditions;
• Including any underlying assumptions about what low lake levels mean in terms of
dissolved oxygen (DO), turbidity, mixing, and overall water quality and supply; and
• Differentiating threats by the adaptive measures that can be applied to them.
Based on the newly defined scenarios (that is, groups of threats), SNWA will revisit baseline and
resilience analyses with the new information on threats and any available information on
likelihood of implementing adaptive measures. SNWA will then generate results using the
revised data, and its adaptation planning may also be revised pending results and adaptive
measure cost data. SNWA plans to complete a more comprehensive climate change vulnerability
assessment using GREAT at a later date based on a completed analysis for all priority
asset/threat pairs to report the relative RRUs and cost per RRU information to aid in decision
making and additional more detailed work in planning for the future.
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GREAT Exercise with Southern Nevada Water Authority
APPENDIX A - EXERCISE PARTICIPANTS
Keely Brooks - Climate Change Policy Analyst (SNWA)
Keiba Crear - Manager Environmental Monitoring and Management (SNWA)
Rick Holmes - Senior Strategic Advisor (SNWA)
Kevin Fisher - Director-Operations (LVVWD)
Laura Jacobsen- Planning Manager (LVVWD)
Marc Jensen - Director- Engineering (SNWA)
Joe Leising - Hydrologist II (SNWA)
Zane Marshall - Director-Environmental Resources (SNWA)
Tom Maher - Senior Resource Analyst (SNWA)
Larry Tamashiro - Resource Analyst (SNWA)
Todd Tietjen - Limnology Project Manager (SNWA)
Jim Watrus - Senior Hydrologist (SNWA)
Gary Wood - Renewable Energy Program Manager (SNWA)
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GREAT Exercise with Southern Nevada Water Authority
APPENDIX B - CONSEQUENCE MATRIX
The following table contains the consequence category definitions and levels defined during the exercise.
Category
Description
Very High
High
Medium
Low
Utility Business Impacts
Revenue or operating income
loss evaluated in terms of the
magnitude and recurrence of
service interruptions.
Long-term and/or significant
loss of expected revenue or
operating income or need for
significant capital investment >
$5,000,000. Increase in
operational expenses (difficulty
recruiting, increased power
cost)
Seasonal or episodic - but minor
- compromise of expected
revenue or operating income, or
need for large capital
investments $1,000, 000 -
$5,000,000
Minor and short-term
reductions in expected revenue
or operating income, or the
need for capital investments
between $100,000 and
$1,000,000. This could include
lowering pumps (~$100,000 per
pump)
Minimal potential for any
attributable loss of revenue or
operating income, and capital
investment requirements are
<$ 100,000
Utility Operational/ Equipment
Damage
Costs of replacing the service
equivalent provided by a utility
or piece of equipment evaluated
in terms of the magnitude of
damage (minimal, minor,
significant, complete loss) and
financial impacts (flexible cost
scale, "$X," can be customized
by each user)
Complete loss of asset;
replacement costs of
>$5,000,000 (e.g., need to
expand capacity to meet higher
peak demands, or need for
improved operational flexibility;
loss of Intake 2/3 pumping
Significant damage to
equipment; costs estimated at
$1,000,000-$5,000,000
($1,000,000 is insurance
deductible for losses other than
earth movement, flooding, or
weather)
Minor damage to equipment;
costs estimated at $100,000-
$1,000,000 (need to adjust
pump levels to low water levels)
Minimal damage to equipment
(<$100,000)
Source/Receiving Water
Impacts
Degradation or loss of source
water or receiving water quality
and/or quantity evaluated in
terms of the recurrence
(minimal, temporary, seasonal
or episodic, long-term)
Long-term compromise of water
quality and/or quantity
(specifically: reduced gw
recharge, increased ET, long-
term extraordinary shortage
condition on CR)
Seasonal or episodic
compromise of water quality
and/or quantity (reduced gw
recharge, increased ET, 3
consecutive years of 40kafy
shortage on CR)
Temporary impact on water
quality and/or quantity (quality
+/or quantity of local gw
aquifers reduced, 3 consecutive
years of 20kafy shortage on CR)
No more than minimal changes
to water quality and/or quantity
Environmental Impacts
Evaluated in terms of
environmental damage or loss
(aside from source water or
other assets) and compliance
with environmental regulations
(minimal, short term, persistent
/ permit violations significant
impact and/or regulatory
enforcement and actions)
Significant environmental
damage - may incur regulatory
action (e.g., climate changes
baseline environment
considered in ESA, making it
more difficult for action agency
to be in compliance)
Persistent environmental
damage - may incur regulatory
action
Short-term environmental
damage - compliance can be
quickly restored (e.g., flood
event temporarily changes temp
& turbidity for key habitats)
No and low impact or
environmental damage
Community/Work Force Health
Impact
Evaluated in terms of the
duration (short or long-term)
and extent (minimal, minor,
localized, or widespread)
Long-term and/or widespread
public health impacts. Health
impact that results in a single
death (e.g., loss of life in a fire)
Short-term and localized public
health impacts
Minor public health impacts
(more challenges for treatment)
No and low impact on public
health
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GREAT Exercise with Southern Nevada Water Authority
APPENDIX C - CLIMATE SCENARIO DATA
The following plots and tables contain the climate data for scenarios defined during the exercise.
Hot and dry model projection: Projected climate conditions for 2060
Average Temperature Data (F)
Annual
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
73.79
52.00
56.52
62.17
70.19
81.81
92.98
97.86
97.45
88.63
75.02
59.25
51.37
Total Precipitation Data
(inches)
Annual
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
3.66
0.53
0.68
0.56
0.11
0.10
0.03
0.32
0.27
0.27
0.20
0.26
0.32
•
98.8
H 937
.c 88.5
£ 833
r67.7
62.6
57.4
52.2
47.0
X*
f
//^
//
/if
//
jff
^'
^Vvv/^
i IF
y*
ejected
\
c
7,
•
,
**
•
•^
^
^
, 77.5
1
/
69.7
62.0
31.0
23.2
15.5
11
.0
Month
Individual symbols
in upper-right of
graphs indicate historical
and projected
annual averages.
Total precipitation (in) during 24-h event
neium
interval
5-y
10-y
15-y
30-y
50-y
100-y
Annual
1.36
1.63
1.76
1.99
2.17
2.40
Winter
(DJF)
0.86
1.04
1.13
1.31
1.45
1.58
Spring
(MAM)
0.63
0.90
1.04
1.36
1.58
1.99
Summer
(JJA)
0.90
1.40
1.76
2.49
3.21
4.57
Fall
(SON)
0.86
1.13
1.27
1.49
1.67
1.95
Projected
Historical | Projected
Return Interval
Page 23
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GREAT Exercise with Southern Nevada Water Authority
Central model projection: Projected climate conditions for 2060
Average Temperature Data (F)
Annual
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
72.28
50.47
55.03
61.34
69.71
79.79
90.32
94.93
93.8
86.99
74.21
59.91
50.64
Total Precipitation Data (inches)
Annual
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
4.61
0.63
0.78
0.57
0.12
0.17
0.09
0.62
0.33
0.39
0.28
0.22
0.43
Total precipitation (in) during 24-h event
r\eiui n
interval
5-y
10-y
15-y
30-y
50-y
100-y
Annual
1.31
1.58
1.72
1.95
2.15
2.39
Winter
(DJF)
0.83
1.01
1.10
1.29
1.43
1.58
Spring
(MAM)
0.61
0.88
1.01
1.33
1.56
1.99
Summer
(JJA)
0.87
1.36
1.72
2.44
3.17
4.56
Fall
(SON)
0.83
1.10
1.23
1.47
1.65
1.94
O Historical | Projected
39
34
23
2.4
1.9
15
1
.5
Return Interval
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GREAT Exercise with Southern Nevada Water Authority
Warm and wet model projection: Projected climate conditions for 2060
Average Temperature Data (F)
Annual
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
71.45
49.45
54.47
60.51
68.12
78.35
89.04
95.34
93.49
86.54
72.35
59.05
50.4
5- 91.4
'£ 864
£ 81.5
IS 76.6
— 71.6
S 667
M 618
Q 569
470
Total Precipitation Data (inches)
Annual
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
5.67
0.76
0.67
0.64
0.14
0.19
0.12
1.18
0.88
0.1
0.25
0.32
0.49
Total precipitation (in) during 24-h event
rceiurn
interval
5-y
10-y
15-y
30-y
50-y
100-y
Annual
1.38
1.65
1.78
2.01
2.20
2.43
Winter
(DJF)
0.87
1.05
1.14
1.33
1.46
1.60
Spring
(MAM)
0.64
0.91
1.05
1.37
1.60
2.02
Summer
(JJA)
0.92
1.42
1.78
2.51
3.25
4.63
Fall
(SON)
0.87
1.14
1.28
1.51
1.69
1.97
hfetorcal • Projected
- sioncsl • Projected
75.3
67.5
6G.G
525
45.0
37.5
30.0
225
15.0
7.5
• .0
f ^ ^ f jf J? ^ jf £ J?
*jT
-------
GREAT Exercise with Southern Nevada Water Authority
APPENDIX D - SCENARIOS WITH THREAT LIKELIHOODS
The following table contains the level of likelihood assessed for each threat, from Low to Very High, in each time period and scenario.
Threats
Changes in SNWA energy use and availability
Changes in residential use
Poor power grid performance
Runoff timing
Reduced snowpack
Lower lake and reservoir levels
Extreme low lake level
Reduced groundwater recharge
High temperatures
Warmer water temperatures
Altered water quality
High flow events
Wildfire
Loss of wetlands
Unhealthy environment
Water cost
Living cost
Invasive species
Likelihood
(Hot & Dry)
2035
n/a
Medium
Medium
n/a
High
High
Low
n/a
Very High
High
High
High
Medium
Medium
Medium
Medium
Medium
Medium
2060
High
Medium
Medium
n/a
High
High
Medium
Medium
Very High
High
High
High
Medium
Medium
Medium
Medium
Medium
Medium
Likelihood
(Central)
2035
n/a
Medium
Medium
Medium
Medium
Medium
Low
n/a
High
High
Medium
High
Medium
Medium
Medium
Medium
Medium
Medium
2060
Medium
Medium
Medium
Medium
High
High
Medium
Medium
High
High
High
High
Medium
Medium
Medium
Medium
Medium
Medium
Likelihood
(Warm & Wet)
2035
n/a
Medium
Medium
Low
Medium
Low
Low
n/a
High
High
Medium
High
Medium
Medium
Medium
Medium
Medium
Medium
2060
Low
Medium
Medium
Medium
Medium
Medium
Low
Medium
High
High
High
High
Medium
Medium
Medium
Medium
Medium
Medium
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GREAT Exercise with Southern Nevada Water Authority
APPENDIX E - BASELINE ANALYSIS - PRELIMINARY RESULTS
The following table lists the preliminary baseline analysis results, using highest consequence level method, for the Hot and Dry
climate scenario (Scenario 1). Consequence levels range from green (lowest risk) to red (highest risk). Source water refers to
consequences that impact quality or quantity of water.
Hot and Dry Climate Scenario
Threat
Lower lake and
reservoir levels
Extreme low
lake level
Asset
Intakes and raw
water conveyance
system
Lake Mead
(Colorado River
Resource)
Power Supply (In
Valley)
SNWA Water
Treatment Systems
Las Vegas Valley
Aquifers
Intakes and raw
water conveyance
system
LVVWD Distribution
Grid and
Conveyance
Lake Mead
(Colorado River
Resource)
SNWA Water
Treatment Systems
Time
Period
2035
2060
2035
2060
2035
2060
2035
2060
2035
2060
2035
2060
2035
2060
2035
2060
2035
2060
Consequence Levels
Business
Low
Medium
Low
Low
Medium
High
Medium
Medium
High
High
High
High
Low
Low
High
High
Equipment
or Facility
Medium
Medium
Low
Low
Medium
High
Medium
Medium
High
High
High
High
Low
Low
High
High
Source
Water
Low
Low
Medium
Low
Medium
High
Medium
Medium
High
Very High
Low
Low
High
High
Very High
Very High
Environmental
Low
Low
Medium
Low
Medium
High
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Community
Low
Low
Low
Low
Medium
High
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Overall
Result
Medium
Medium
Medium
Low
Medium
High
Medium
Medium
High
Very High
High
High
High
High
Very High
Very High
RRUs
45
45
45
40
45
55
45
45
55
75
40
45
40
45
50
60
Page 27
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GREAT Exercise with Southern Nevada Water Authority
Hot and Dry Climate Scenario
Threat
Poor power grid
performance
Warmer water
temperatures
Altered water
quality
Changes in
residential use
Asset
Las Vegas Valley
Aquifers
Intakes and raw
water conveyance
system
LVVWD Distribution
Grid and
Conveyance
Power Supply (In
Valley)
SNWA Water
Treatment Systems
Intakes and raw
water conveyance
system
LVVWD Distribution
Grid and
Conveyance
SNWA Water
Treatment Systems
Intakes and raw
water conveyance
system
SNWA Water
Treatment Systems
Intakes and raw
water conveyance
system
LVVWD Distribution
Time
Period
2035
2060
2035
2060
2035
2060
2035
2060
2035
2060
2060
2035
2060
2035
2060
2035
2060
2035
2060
2035
2060
2035
Consequence Levels
Business
High
High
Low
Low
Low
Low
Medium
High
Very High
Very High
Low
Low
Low
Low
Medium
Low
Low
Low
Low
Low
Low
Low
Equipment
or Facility
High
High
Very High
Very High
Low
Low
Medium
High
Very High
Very High
High
High
High
Medium
Medium
Very High
Very High
Medium
Medium
Low
Low
Low
Source
Water
High
Very High
Low
Low
Low
Low
Medium
High
Low
Low
Low
Low
Low
Medium
Very High
Low
Low
Medium
Medium
Low
Low
Low
Environmental
Low
Low
Low
Low
Low
Low
Medium
High
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Community
Low
Low
Low
Low
Low
Low
Medium
High
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Overall
Result
High
Very High
Very High
Very High
Low
Low
Medium
High
Very High
Very High
High
High
High
Medium
Very High
Very High
Very High
Medium
Medium
Low
Low
Low
RRUs
55
75
60
60
37
37
40
45
60
60
55
55
55
45
^
75
75
45
45
37
37
37
Page 28
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GREAT Exercise with Southern Nevada Water Authority
Hot and Dry Climate Scenario
Threat
High flow events
Invasive species
Reduced
groundwater
recharge
Asset
Grid and
Conveyance
Power Supply (In
Valley)
SNWA Water
Treatment Systems
Las Vegas Valley
Aquifers
LVVWD Distribution
Grid and
Conveyance
Power Supply (In
Valley)
SNWA Water
Treatment Systems
Intakes and raw
water conveyance
system
SNWA Water
Treatment Systems
Las Vegas Valley
Aquifers
Time
Period
2060
2060
2035
2060
2060
2035
2060
2035
2060
2035
2060
2035
2060
2035
2060
2060
Consequence Levels
Business
Low
Low
Low
Low
Medium
Low
Low
Medium
Medium
Medium
Medium
Low
Low
Low
Low
Low
Equipment
or Facility
Low
Low
Low
Low
Medium
Low
Low
Medium
Medium
Medium
Medium
Medium
Medium
Medium
Medium
Medium
Source
Water
Low
Low
Low
Low
Medium
Low
Low
Low
Low
Medium
Low
Low
Low
Medium
Medium
Medium
Environmental
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Community
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Overall
Result
Low
Low
Low
Low
Medium
Low
Low
Medium
Medium
Medium
Medium
Medium
Medium
Medium
Medium
Medium
RRUs
37
37
37
37
40
40
40
45
45
45
45
40
40
40
40
40
Page 29
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GREAT Exercise with Southern Nevada Water Authority
APPENDIX F - EXISTING ADAPTIVE MEASURES
The following table lists some of the adaptive measures defined in the GREAT analysis with the assets and threats where they were
used (selected) during assessments.
Existing Measures for Intakes
Ambient water temperature monitoring
Back-up power
Demand management
Diversify power supply
Drought contingency plan
Emergency response plan - water supply
(power)
Energy efficiency improvements
Groundwater/ aquifer recharge
Groundwater Monitoring Program
(Includes In Valley and CLWP)
Keep all ground water available
Leakage reduction program
New third intake
Optimize well system
Optimized chemical use
Optimized pumping
Stakeholder engagement
Storm storage (capture excess CR flows)
Water quality models (dist sys in-house)
Altered water
quality
SI
X
X
Changes in
residential use
SI
X
X
X
X
S2
X
X
X
X
S3
X
X
X
X
Extreme low
lake level
SI
S2
S3
Lower lake and
reservoir levels
SI
X
X
X
S2
X
X
X
S3
X
X
X
Poor power grid
performance
SI
X
X
X
X
X
X
X
X
S2
X
X
X
X
X
X
X
X
S3
X
X
X
X
X
Warmer water
temperatures
SI
X
X
S2
S3
Page 30
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GREAT Exercise with Southern Nevada Water Authority
Existing Measures for Lake Mead
Access LVV bank
Additional demand management
CLWP Groundwater Development Project
CRBS Options for CR System benefit
CRBS Options for Nevada benefit
Expand groundwater monitoring program
(Includes In Valley and CLWP)
Interconnections
Maintain interim supplies (bank recovery
and/or ICS)
Optimize use of the 3rd intake
Regional electricity demand models
Strengthen drought contingency plan
Strengthen leakage reduction program
Supply-demand models
Weather forecast monitoring
Existing Measures for Treatment
Adaptive rates
Add advanced treatment
(Microfiltration/RO) (Altered treatment)
Add chloramination (Altered treatment)
Addtl flood control - dirt levees
Addtl flood control - Long-term project
Alternate water supplies
CLWP Groundwater Development Project
Community outreach
Altered water
quality
SI
SI
Changes in
residential use
SI
SI
S2
S2
S3
S3
X
X
Extreme low
lake level
SI
X
X
X
X
X
X
X
X
X
X
X
X
X
X
SI
S2
X
S2
S3
X
S3
Lower lake and
reservoir levels
SI
X
X
X
X
X
X
X
X
X
X
X
X
SI
X
X
X
S2
X
S2
S3
X
S3
Poor power grid
performance
SI
SI
S2
S2
S3
S3
Warmer water
temperatures
SI
SI
X
X
X
S2
S2
S3
S3
Page 31
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GREAT Exercise with Southern Nevada Water Authority
Existing Measures for Treatment (cont.)
Demand management
Development code changes
Effluent re-use
Energy efficiency improvements
Improve well use optimization
Increase air stripping dist sys (Altered
treatment)
Install influent cooling systems (Altered
treatment)
New third intake
Optimized pumping
Point of use DW treatment (carbon/filt)
Stakeholder engagement
Water resource acquisition
Existing Measures for Distribution
Add chloramination (Altered treatment)
Additional water quality model runs (Lake
only)
Air stripping with dist sys (Altered
treatment)
Alt water supply (bottled water, etc.)
Aquifer recharge for water age manag
CLWP Groundwater Development Project
Connect to CLWP GW Devel Pro]
Deeper intake (upstream pipeline)
Demand management
Dist sys temperature monitoring
Altered water
quality
SI
SI
Changes in
residential use
SI
SI
S2
S2
S3
S3
Extreme low
lake level
SI
X
SI
S2
S2
S3
S3
Lower lake and
reservoir levels
SI
X
X
X
X
X
SI
X
S2
S2
X
S3
S3
X
Poor power grid
performance
SI
X
X
SI
S2
X
X
X
X
X
S2
S3
X
X
X
X
X
S3
Warmer water
temperatures
SI
X
X
X
X
SI
X
X
X
X
X
S2
S2
X
X
X
X
X
X
S3
S3
X
X
Page 32
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GREAT Exercise with Southern Nevada Water Authority
Existing Measures for Distribution (cont.)
Emergency response plan - water supply
Expand distribution flexibility
Groundwater models (LVV)
Improve well use optimization
Increase air stripping dist sys (Altered
treatment)
Leakage reduction program
New technol or chemicals (treatment)
Optimize use of the 3rd intake
Point of use DW treatment (carbon/filt)
R&D predictive methods / ID critical
factors
Regulatory flexibility
Regulatory flexibility (lite)
Temperature monitoring
Water quality models (dist sys in-house)
Altered water
quality
SI
Changes in
residential use
SI
X
S2
X
S3
X
Extreme low
lake level
SI
X
X
S2
X
X
S3
X
X
Lower lake and
reservoir levels
SI
X
S2
X
S3
X
Poor power grid
performance
SI
S2
S3
Warmer water
temperatures
SI
X
X
X
X
X
X
X
S2
X
X
X
X
X
X
S3
X
X
Page 33
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GREAT Exercise with Southern Nevada Water Authority
APPENDIX G - ADAPTATION PACKAGES
The following table lists the preliminary adaptation packages discussed during exercise, each based on a trigger or threshold related to
assessed threats.
Adaptation
Package
Description
Triggers/
Thresholds
Adaptive
Measures
Short-term package
for challenge with
lake water quality
Increased algal
blooms
Lower lake levels
Decreased dissolved
oxygen
Additional water
quality modeling
R&D to identify
critical factors
Monitor
temperature
Monitor weather
Optimize third
intake
Long-term package for
challenge with lake
water quality
Increased algal blooms
Lower lake levels
Decreased dissolved
oxygen
Alter treatment by
adding chloramination
CBRS options for CR
benefit
Supply and demand
models
New
technology/chemicals
Advanced treatment
(microfiltration/RO)
Regulatory flexibility
(Phase 1)
Short-term package
for challenge with
temperature mgmt in
distribution system
Increased
trihalomethanes
Resident water
outage
Taste and odor
complaints
Improve well use
optimization
R&D to identify
critical factors
Increase air stripping
Aquifer recharge for
water management
Management of
chloramination
Maintain
partnerships with
land developers
Volume reduction
mgmt
Long-term package
for challenge with
temperature mgmt in
distribution system
Increased
trihalomethanes
Resident water
outage
Taste and odor
complaints
Connect to CLWP
groundwater project
Add chloramination
to treatment
Aquifer recharge for
water management
Maintain partnerships
with land developers
New
technology/chemicals
Access LVV GW bank
Regulatory flexibility
(Phase 1)
Package to address
temperature
challenge beyond all
other options
Regulatory violation
Install influent
cooling system
Extend third intake
deeper into lake
Point of use
treatment/ supply
bottled water
Pursue regulatory
flexibility (Phase II)
Page 34
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GREAT Exercise with Southern Nevada Water Authority
APPENDIX H - RECOMMENDATIONS FOR FUTURE TOOL
DEVELOPMENT AND TRAINING
Overall
• Develop separate tracks for basic versus advanced users, possibly several opportunities
where users can throw the switch to go to the alternate track
• Check accessibility of training videos
• Add Equal button to consequence weighting screen
Baseline and Resilience Analysis
• Include a way to filter analysis summary trees to just show current work (default should
be to show all so you can identify gaps)
• Refine adaptive measure contribution screen
• Percentages for adaptive measure contribution screen are not intuitive, change method
here to rank order, rank weight or other means or comparison (for interface, consider
click and drag or star system, also consider adding positive and negative switch)
• Add scale of likelihood of implementation
• Add note for options to be used 'if-available' (e.g. for groundwater development project)
• Add note or guidance regarding the need to consider likelihood of implementation in
addition to (as part of) any cost-benefit analysis
• Add import of 2035 adaptive measures to 2060 analysis (SNWA group kept having to re-
populate the same measures)
Planning
• Add a drop down to allow user to put in their description of cost info (adaptive measure
screen)
• Add an option to go back and modify or split adaptive measures during Adaptation
Planning
• Update energy and green infrastructure options in GREAT with those from updated
Adaptation Strategies Guide
• Identify method to modify adaptive measures ad hoc (e.g., during Planning)
• Include button to grab all adaptive measures related to each asset to avoid the repetition
of considering adaptive measures related to analyses again during package design
Results and Reports
• Add interim products, or exports of results to encourage users and document progress
• Add functionality to display results under different assumptions
• Add functionality for right-click to generate report for a specific asset
Page 35
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GREAT Exercise with Southern Nevada Water Authority
• Add functionality to track items that need to be modified (e.g., flag items and add
comments about future modifications), consider adding comment report
• Add check on generated reports to highlight areas that need to be re-visited (SNWA
assessment and costs not complete)
With regard to future training and tool guidance, SNWA suggested that EPA:
• Consider developing a training module or class to train utility representatives.
• Explore additional ways to facilitate group collaboration (e.g., other ways to enter data
into the tool, such as importing MS Excel spreadsheets, coupled with hands-on time with
the tool). Participants noted that interacting with the tool during the exercise greatly
increased their understanding of how it worked.
• Consider providing a facilitation package (e.g., PowerPoint presentations, worksheets,
Excel templates and fact sheets describing common pitfalls and how to avoid them).
• Consider ways to convey information to utilities regarding the time commitment involved
in conducting a full risk assessment.
• Emphasize that GREAT is focused on assessing effectiveness of adaptation plans and that
other considerations such as financial capacity, trade-offs and political feasibility are not
explicitly taken into account.
Page 36
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Climate Resilience Evaluation and Awareness Tool (GREAT)
Exercise with Southern Nevada Water Authority
CLIMATE READY
^WATER UTILITIES
&ER&
Office of Water (4608-T) EPA 817-S-13-002 January 2014
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