&EPA
EPA/600/
F/March 2011/www.epa.gov
United States
Environmental Protect! o
Agency
Climate Change Vulnerability
Assessments: Four Case Studies
of Water Utility Practices
United States Environmental Protection Agency
Office of Research and Development, National Center for Environmental Assessment
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EPA/600/R-10/077F
March 2011
Climate Change Vulnerability Assessments:
Four Case Studies of Water Utility Practices
Global Change Research Program
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Washington, DC 20460
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DISCLAIMER
This document has been reviewed in accordance with U.S. Environmental Protection
Agency Policy and approved for publication. Mention of trade names or commercial products
does not constitute endorsement or recommendation for use.
Preferred citation:
U.S. Environmental Protection Agency (EPA). (2011) Climate change vulnerability assessments:
four case studies of water utility practices. Global Change Research Program, National Center
for Environmental Assessment, Washington, DC; EPA/600/R-10/077F. Available from the
National Technical Information Service, Springfield, VA, and online at
http ://www. epa.gov/ncea.
ii
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CONTENTS
LIST OF TABLES v
LIST OF FIGURES v
FOREWORD vi
AUTHORS, CONTRIBUTORS, AND REVIEWERS vii
EXECUTIVE SUMMARY viii
1. INTRODUCTION 1
1.1. SELECTION OF CASE STUDIES 2
1.2. DATA COLLECTION 4
2. EAST BAY MUNICIPAL UTILITY DISTRICT 5
2.1. BACKGROUND 5
2.2. DESCRIPTION OF THE WATER SYSTEM 6
2.2.1. Drinking Water Supply System 6
2.2.1.1. Water Sources 6
2.2.1.2. Water Distribution 8
2.2.1.3. Water Use 8
2.2.1.4. Demand Management 8
2.2.2. Wastewater System 9
2.3. CLIMATE CHANGE PROJECTIONS AND RISKS 9
2.4. CLIMATE CHANGE VULNERABILITY ASSESSMENTS 11
2.4.1. Flooding and Sea Level Rise 11
2.4.2. Hydropower Generation 12
2.4.3. Water Supply 12
2.4.3.1. Temporal Shift in Runoff 14
2.4.3.2. Decrease in Annual Precipitation 14
2.4.3.3. Increased Demand 15
2.4.4. Water Quality 15
2.5. APPLICATION OF VULNERABILITY ASSESSMENT INFORMATION 16
3. NEW YORK CITY DEPARTMENT OF ENVIRONMENTAL PROTECTION 17
3.1. BACKGROUND 17
3.2. DESCRIPTION OF THE WATER SYSTEM 19
3.2.1. Water Supply System 19
3.2.2. Wastewater System 21
3.3. CLIMATE CHANGE PROJECTIONS AND RISKS 22
3.4. CLIMATE CHANGE VULNERABILITY ASSESSMENTS 24
3.5. APPLICATION OF VULNERABILITY AS SES SMENT INFORMATION 27
3.5.1. Decreasing Turbidity 27
3.5.2. Minimizing Flooding 28
3.5.3. Minimizing Supply and Demand Imbalances 28
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CONTENTS (continued)
3.5.4. Decreasing Combined Sewer Overflows 29
3.5.5. Adapting to Flood Risk 29
4. SEATTLE PUBLIC UTILITIES 30
4.1. BACKGROUND 30
4.2. DESCRIPTION OF THE WATER SYSTEM 31
4.2.1. Water Supply System 31
4.2.2. Wastewater System 33
4.3. CLIMATE CHANGE PROJECTIONS AND RISKS 34
4.4. VULNERABILITY ASSESSMENT 37
4.4.1. Water Supply 38
4.4.2. Water Demand 38
4.4.3. Storms and Runoff. 39
4.5. APPLICATION OF VULNERABILITY ASSESSMENT INFORMATION 39
4.5.1. Water Supply 40
4.5.2. Storms and Runoff. 41
5. SP ART ANBURG WATER 42
5.1. BACKGROUND 42
5.2. DESCRIPTION OF THE WATER SYSTEM 42
5.2.1. Water Supply System 42
5.2.2. Wastewater System 44
5.3. CLIMATE CHANGE PROJECTIONS AND RISKS 45
5.4. CLIMATE CHANGE VULNERABILITY ASSESSMENTS 46
5.4.1. Water Quantity 46
5.4.2. Water Quality 47
5.4.3. Infiltration/Inflow 48
5.5. APPLICATION OF VULNERABILITY ASSESSMENT INFORMATION 48
6. SUMMARY 51
REFERENCES 53
IV
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LIST OF TABLES
Table 1. Key attributes of water utility case studies 3
Table 2. Projected baseline climate and mean annual changes for New York City 22
Table 3. Projections of changes in annual mean temperature and precipitation for the 2020s,
2040s, and 2080s 35
LIST OF FIGURES
Figure 1. Location of water utility case studies 3
Figure 2. East Bay Municipal Utility District (EBMUD) service area and ultimate service
boundary 7
Figure 3. New York City Department of Environmental Protection (DEP) system overview.... 18
Figure 4. Seattle Public Utilities service area 32
Figure 5. Reservoirs and watersheds of the Spartanburg water system 43
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FOREWORD
Global climate change can have a range of potentially adverse effects on water resources.
EPA's Global Change Research Program (GCRP), within the Office of Research and
Development (ORD), conducts research to support the development of sustainable solutions for
protecting human health and the environment from the effects of air pollution and climate change
while sustainably meeting the demands of a growing population and economy. The focus on
developing sustainable solutions requires innovative, systems-oriented science that engages end-
users from problem-formulation through product application. GCRP research activities
addressing the implications of climate change on water quality supports EPA's mission to protect
human health and the environment, and is consistent with the goals outlined in the EPA Office of
Water's National Water Program Strategy: Response to Climate Change.
This report was developed in partnership with the EPA Office of Water (EPA OW). The
report is a companion to a report released by EPA OW in 2010 titled Climate Change
Vulnerability Assessments: A Review of Water Utility Practices. This report can be found at
http://water.epa.gov/scitech/climatechange/upload/Climate-Change-Vulnerability-Assessments-
Sept-2010.pdf. The 2010 report from the Office of Water describes the range of different
approaches being applied by eight U.S. water utilities to assess their vulnerability to climate
change. The current report expands on this discussion by presenting a series of case studies that
describe in more detail the specific issues, analyses, and actions taken by four U.S. water utilities
to assess and respond to climate change. The issue of climate change is complex and will
challenge utilities as they strive to meet water quality goals. We hope that the case studies
presented in this report will inform, inspire, or otherwise support the efforts of other utilities and
water managers to better understand and respond to the challenge of climate change.
We want to thank the authors, reviewers, and entire project team for their effort in
preparing this report. Success in producing this report has depended first and foremost on the
dedication and enthusiasm of this team. We also want to acknowledge the collaboration of EPA
Office of Research and Development and Office of Water in this effort, as well as the
cooperation of the utilities examined. While much remains uncertain concerning future climate
change, it is clear that our best path forward is through continued research, partnership and
collaboration to meet our common goals.
Andy Miller
Acting National Program Director for Global Change Research
Office of Research and Development
U.S. Environmental Protection Agency
Karen Metchis
Senior Policy Advisor for Climate Change
Office of Water
U.S. Environmental Protection Agency
VI
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AUTHORS, CONTRIBUTORS, AND REVIEWERS
Preparation of this report was conducted by Abt Associates Inc., Cambridge,
Massachusetts, under EPA Contract EP-C-07-023, and Stratus Consulting, Inc., Boulder,
Colorado, under subcontract to Abt Associates Inc. Thomas Johnson served as the Technical
Project Officer.
AUTHORS
Jason Vogel, Stratus Consulting, Inc.
Viktoria Zoltay, Abt Associates Inc.
Joel Smith, Stratus Consulting, Inc.
Debra Kemp, Abt Associates Inc.
Thomas Johnson, U.S. EPA, ORD
REVIEWERS
The authors are very grateful for the many thoughtful and constructive comments on an
earlier draft of this report provided by Neil Grigg, Paul Kirshen, Simon Pollard, and Len Wright.
The authors are also grateful for the many constructive comments received from the public
during a public comment period on an earlier draft of this report.
ACKNOWLEDGMENTS
This report could not have been possible without the generous help and support of staff
from each of the utilities featured in the report: Alan Cohn, New York City Department of
Environmental Protection; Dennis Diemer, East Bay Municipal Utility District; Paul Fleming
and Joan Kersnar, Seattle Public Utilities; and Rebecca West, Spartanburg Water. The authors
also wish to thank Karen Metchis, Y. Jeffrey Yang, and Meredith Warren at U.S. EPA, and the
entire project team at Abt Associates, Stratus Consulting, and U.S. EPA for their help and many
thoughtful comments and suggestions that contributed to this report.
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EXECUTIVE SUMMARY
Concern about the potential effects of climate change on the quantity, quality, timing, and
demand for water is growing. The implications of climate change for long-lived,
capital-intensive water infrastructure is a particular concern. In 2009, the U.S. Environmental
Protection Agency sponsored the First National Expert and Stakeholder Workshop on Water
Infrastructure Sustainability and Adaptation to Climate Change (U.S. EPA, 2009a). This
workshop highlighted a need for improved information and tools to help water utilities better
understand and manage the risk of future impacts due to climate change. Many utilities are
already addressing this challenge. One finding of this workshop was that compiling case studies
of current water utility activities related to climate change adaptation would be useful to help
those in the water sector learn from each other.
This report presents case studies describing the approaches taken by four water utilities in
the United States to assess their vulnerability to climate change. The report is not intended to be
a comprehensive listing of assessment approaches or utilities conducting vulnerability
assessments. Nor does this report represent the full range of potential approaches for assessing
and managing climate risk. Rather, the purpose of this report is to illustrate a range of
approaches that selected water utilities have taken to understand and respond to climate risk.
Water resources decision making is a complex, multi-factorial process, and determining
the impact of a single factor, such as climate change, on decision making is a challenging
question. In this report we present the facts from which utility managers, resource planners,
climate scientists, and others can draw conclusions and lessons learned. This report is
descriptive by design. It does not evaluate the approaches used. Furthermore, because this
report is empirical in nature, it might not describe all topics that water utilities need to consider
to assess their climate risk.
The following four utilities are featured as case studies in this report:
• East Bay Municipal Utility District (Contra Costa and Alameda Counties, California)
• New York City Department of Environmental Protection (New York, New York)
• Seattle Public Utilities (Seattle, Washington)
• Spartanburg Water (Spartanburg, South Carolina).
The selected utilities differ in terms of their geographic location, size, and the types of impacts
they could face from climate change.
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EAST BAY MUNICIPAL UTILITY DISTRICT
East Bay Municipal Utility District (EBMUD) used an elaborate policy analysis when
designing its Water Supply Management Program (WSMP) 2040 (WSMP 2040; EBMUD,
2009b). The objective of the WSMP 2040 was to identify and recommend a portfolio of projects
for meeting dry-year water needs through 2040.: The WSMP 2040 process consisted of
identifying potential adaptations, bundling them into 14 different portfolios, screening those
portfolios based on historic hydrology, and then modeling 5 portfolios under climate change
scenarios. EBMUD applied a "bottom-up" approach for the analyses by identifying climate
factors most likely to affect the system's reliability and testing that reliability to changes in those
factors that are projected to occur by 2040 (e.g., a 4°F increase in average daily temperatures
between 1980 and 2040 or a 20% decrease in precipitation) (EBMUD, 2009a). EBMUD's
analyses reaffirmed the need for a strategy that is flexible and is adaptable to further changes in
observed climate and to refinements in climate change projections (EBMUD, 2009b).
NEW YORK CITY DEPARTMENT OF ENVIRONMENTAL PROTECTION
To analyze vulnerability, the New York City Department of Environmental Protection
(DEP) examined potential impacts of climate change on the availability of water, turbidity, and
eutrophication. The vulnerability analyses identified several potential challenges to New York
City's water supplies and quality, including increased demand, reduced inflows during the spring
thaw season, and increased risk of nutrient loadings and eutrophi cation. Additionally,
precipitation changes, sea level rise, and consequent increased salinity levels in the Hudson
River could pose challenges to the City's drainage and wastewater treatment systems. DEP has
identified a wide array of initiatives to reduce risks from these potential outcomes. Initiatives
include developing a model-based reservoir operation support tool that will allow reservoir
operations to be tailored to future climate conditions, relying more on the soon-to-be-filtered
Croton water supply during turbidity events, building cost-effective grey infrastructure, making
use of natural features such as the wetlands in Staten Island's Bluebell, and promoting water
conservation. DEP's extensive vulnerability studies have leveraged momentum for climate
change considerations in both strategic and capital planning. For instance, DEP promotes the
benefits of green infrastructure for adapting to climate change impacts (e.g., increased heavy
precipitation events and intensifying of the urban heat island effect), as part of its broad, citywide
effort to better manage stormwater.
Existing supplies were estimated to be sufficient during normal and wet years.
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SEATTLE PUBLIC UTILITIES
Seattle Public Utilities (SPU) has worked closely with the Climate Impacts Group (CIG)
at the University of Washington (UW) since 2002 on two studies to assess climate change
impacts. In the most recent study, UW-CIG selected global climate models to capture a range of
conditions, downscaled them statistically, and ran the outputs through a hydrology model. These
results were used in SPU's water supply planning model to examine the effect of climate change
on SPU system performance. SPU also used the downscaled data to project changes in demand
for water. All climate change scenarios modeled resulted in an estimated decrease in water
supplies. The most direct use of the vulnerability assessment by SPU was for water planners to
test the effect of different operational assumptions on water supply availability. SPU also
identified far-reaching adaptations to use in future decades if demand exceeds water supplies
because of either population growth or climate change.
SPARTANBURG WATER
Spartanburg Water is an example of a relatively small utility that did not conduct
quantitative vulnerability assessments (e.g., model-based assessments), but was able to use
information on climate change together with recent extreme climate events to consider climate
change in management decisions. South Carolina has experienced several extreme droughts and
hurricanes in recent years and anticipates that climate change will exacerbate these extreme
events. With lower low flows in receiving streams during droughts, wastewater treatment plants
could be required to upgrade their technology to reduce discharge loads. Also, more intense
precipitation could result in greater pollutant loadings from runoff to the receiving streams. In
response to these concerns and to plan for projected population increases, Spartanburg Water
made several changes in its infrastructure and operations. Recent concerns about water shortages
led Spartanburg Water to assert its rights to limit water withdrawals from the reservoir for lawn
irrigation during droughts. The utility also launched an aggressive water conservation program
and, upon the installation of new pipes, decided to keep the old pipes in place for additional
capacity to handle surges from stormwater. These adaptations are consistent with Spartanburg
Water's experience with recent extreme events and concerns about population growth and
climate change.
OBSERVATIONS ACROSS THE CASE STUDIES
The following summary observations can be made based on these case studies regarding
the conduct and use of climate change vulnerability assessments to support adaptation:
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• Conducting climate change vulnerability assessments appears to have increased
awareness of climate change risks, informed decision making, and supported adaptation
at the utilities featured in this report. One theme emerging from the case studies is the
need to consider climate change in a holistic context, taking into account all factors
affecting system performance.
• Utilities have worked with climate scientists and modelers to obtain data and gain insight
into how climate science can be used to inform their decision making. SPU collaborated
with the UW-CIG, DEP collaborated with Columbia University and the City University
of New York, and EBMUD used an analysis conducted by the State of California and the
California Climate Change Center. In contrast, Spartanburg relied on information
gathered from briefings and staff contact with other utilities through participation in the
Water Environment Federation and the American Water Works Association but did not
formally collaborate with the climate change research community to develop
region-specific data on their climate change risks.
• Uncertainties in vulnerability assessments or climate science need not delay adaptation
action. All four utilities described in this report have taken action to reduce their climate
risk despite significant, remaining uncertainties regarding the potential impacts of climate
change. Often, these actions also address other concerns, such as managing limited
supplies using water conservation or water reuse. Nonetheless, climate change
vulnerability analyses can help inform and prioritize among management decisions.
• The large utilities used a wide array of climate change scenarios to capture some of the
uncertainty about future climate change. EBMUD conducted a "bottom-up" approach by
performing sensitivity analyses to improve its understanding about how climate change
could affect particular elements of its water resource system. SPU and DEP conducted
what are often referred to as "top-down" approaches driven by climate change scenarios
and models.2
• Vulnerability analyses to date have focused mainly on water supply and demand. All
four utilities focused their climate change impacts and vulnerability work principally on
water supply and demand. Although the utilities expressed concern about the effects of
climate change on water quality, urban drainage, wastewater, and other aspects of their
systems, these areas have not yet received the same level of attention as water supply.
• The utilities used system-specific models to understand and manage potential climate
impacts on their systems. All studies except Spartanburg Water used their system
hydrology, operations, or planning models to evaluate the effects of potential climate
change on their systems. The models were used to assess whether operational changes
would be sufficient to cope with the effects of climate change, or whether system
changes, such as adding supplies or further reducing demand, also were necessary. These
models did not always align with the output of climate models, necessitating tailored use
of climate projections for each utility. Spartanburg Water used existing system models to
For more on the difference between "top-down" and "bottom-up" approaches, see Miller and Yates (2006), Freas
et al. (2008), and Stratus Consulting and MWH Global (2009).
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understand their system's behavior and qualitatively determine expected climate change
impacts.
• The case studies demonstrate that a variety of methods can be used to understand
vulnerability and analyze adaptation options. Scenario analyses, sensitivity analyses,
state-of-the-science literature reviews, and peer information sharing were used in
different combinations in the four case studies to understand the potential impacts of
climate change. The sensitivity analysis EBMUD performed on their existing system
model and the literature review and information gathering from peers Spartanburg Water
performed demonstrate two paths that utilities lacking the financial and staff resources to
support detailed modeling studies can take to assess their vulnerability to climate change.
• Utilities expressed an interest in having their needs reflected in future research. Utilities
specifically requested higher resolution climate change projections for the spatial and
temporal scales at which they operate, probabilities associated with projected changes,
and guidance on appropriate climate change parameters and scenarios to consider and
plan for in their regions. One recommendation was to establish a central repository of
data to support climate change and adaptation analysis.
• The results of vulnerability assessments by the four utilities were used in different ways to
inform and support adaptation. SPU responded directly to the results of the vulnerability
analysis by evaluating the impact of conservative operational assumptions on reservoir
management. The other utilities used their vulnerability assessments to increase
knowledge about their climate change risks, integrate information on these risks into
decision making, and provide support for adaptation measures.
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1. INTRODUCTION
Concern about the potential effects of climate change on the quantity, quality, timing, and
demand for water3 is growing. In particular, decisions about water infrastructure have long-term
implications because the infrastructure built today likely will be in place for decades. In 1997,
the American Water Works Association (AWWA) issued a statement expressing the need for
water utilities to begin planning for consequences of climate change (AWWA, 1997). In 2004,
AWWA teamed with the National Center for Atmospheric Research to publish guidance for
municipal utilities on how to address climate change (Miller and Yates, 2006). Three years later,
eight major municipal water utilities formed the Water Utility Climate Alliance (WUCA) to
"provide leadership and collaboration on climate change issues affecting the country's water
agencies" (WUCA, 2010).
Vulnerability to climate change, as defined by the Intergovernmental Panel on Climate
Change (IPCC), refers to the exposure, sensitivity, and adaptive capacity of systems to climate
change (Smit et al., 2001). Exposure consists of the type of change a system experiences. A
coastal city might be exposed to a 3-foot sea level rise, while an inland city would not.
Sensitivity is the effect that climate change can have on a system assuming no planned
adaptation. For example, climate change is projected to reduce the growth of many crops but
increase the growth of others. The sensitivity of these crops to climate change differs. Adaptive
capacity refers to the potential or ability of a system to adapt to the effects of climate change
(Smit et al., 2001). The adaptive capacity of a system is important, for example, in
distinguishing the vulnerability of wealthy and poor societies or human systems versus
ecosystems. Wealthier societies, in general, have greater adaptive capacity and, thus, on
average, are considered less vulnerable to climate change than poorer societies (Parry et al.,
2007).
Several water utilities have begun to assess the potential vulnerability of their systems to
climate change. Many are considering whether their infrastructures or operations should be
changed now or in the future to adapt to climate change. In 2009, the U.S. Environmental
Protection Agency (EPA) sponsored the First National Expert and Stakeholder Workshop on
Water Infrastructure Sustainability and Adaptation to Climate Change (U.S. EPA, 2009a). This
workshop highlighted a need for improved information and tools to help water utilities better
understand and manage the risk of future impacts due to climate change. One finding of this
workshop was that compiling case studies of current water utility activities related to climate
change adaptation would help others in the water sector learn from each other.
3 For information on climate change and its projected impacts on water resources, see IPCC, 2008 and USGCRP,
2009.
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This report presents case studies describing the approaches taken by four water utilities in
the United States to assess their vulnerability to climate change. The report is not intended to be
a comprehensive listing of assessment approaches or utilities conducting vulnerability
assessments (for more detail on these topics, see the companion report, U.S. EPA, 2010).
Rather, its purpose is to illustrate a range of issues and current approaches taken by selected
utilities that are leaders in climate adaptation to understand and respond to climate risk. Climate
change and its effect on water resources is complex and will require ongoing attention and study.
We hope the information gleaned from these case studies will be of use to water utilities and
other members of the water resources community in illustrating a range of vulnerability studies
being applied to guide adaptation decision making. This report is also intended to help identify
the types of technical assistance needed to support such assessments.
A companion report is available, Climate Change Vulnerability Assessments: A Review
of Water Utility Practices (U.S. EPA, 2010). The purpose of that report is to identify and
categorize the models and techniques that eight water utilities are using to understand their
vulnerability to climate change. The current report provides a more detailed examination of the
approaches taken by three of the eight utilities discussed in U.S. EPA (2010). The current report
also includes discussion of one utility not included in U.S. EPA (2010).
1.1. SELECTION OF CASE STUDIES
Many water utilities are active in developing climate adaptation strategies and could have
been included here. Limiting the scope of this report to just four utilities, however, was
necessary for practical reasons. The four utilities featured in this report are (Figure 1)
• East Bay Municipal Utility District (EBMUD) in Contra Costa and Alameda
Counties, California
• New York City Department of Environmental Protection (DEP) in New York, New York
• Seattle Public Utilities (SPU) in Seattle, Washington
• Spartanburg Water in Spartanburg, South Carolina.
The selected utilities differ in terms of their geographic location, size, and the types of
impacts they could face from climate change (Table 1). Three of the four serve more than a
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Seattle, WA
Contra Costa
and Alameda
counties, CA
i v
/ Spartanburg, SC
Figure 1. Location of water utility case studies
Table 1. Key attributes of water utility case studies
Utility
East Bay
Municipal
Utility District
(EBMUD)
Department of
Environmental
Protection
(DEP)
Seattle Public
Utilities
(SPU)
Spartanburg
Water
Location
Alameda and
Contra Costa
Counties,
California
New York,
New York
Seattle,
Washington
Spartanburg,
South Carolina
Population
served
1.3 million
9.2 million
1.4 million
180,000
Key climate change risks
• Change in timing of runoff
• Reduction in water supply
• Sea level rise
• Increases in turbidity, eutrophi cation,
and combined sewer overflows
• Sea level rise
• Change in timing of runoff
• Reduction in water supply
• Increases in flood risks and combined
sewer overflows
• Increases in drought and coastal storms
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million people. The smaller Spartanburg Water was selected because of its size and because it
took a qualitative approach to understanding its vulnerability to climate change. The western
utilities are mainly concerned about potential changes in the timing of and reductions in runoff,
while the eastern utilities are concerned about changes in extreme events and consequences of
these events for water quantity and quality, and the performance of their systems.
Each selected utility has examined or is examining the vulnerability of its system to
climate change. The methods used span a range from detailed, quantitative analyses to a more
qualitative approach for examining climate change and lessons learned from recent extreme
events. All four utilities have also considered or made changes to planning, operations, or
infrastructure that, if not driven by the results of their analyses, are at least consistent with
adapting to climate change. These four case studies are not necessarily representative of how all
utilities are considering climate change. Nor do they represent the full range of potential
approaches for assessing and managing climate risk. They do, however, illustrate and provide
insight into how information on vulnerability to climate change is being developed and used.
1.2. DATA COLLECTION
The information presented in this report was collected from publically available
documents and interviews with utility staff. Specifically, the report focuses on
• Background of the utility—e.g., location, size of utility
• Description of the utility, including the water supply (which includes provision of
drinking water) and wastewater system
• Climate change projections and why the utility was interested in vulnerability to climate
change
• Approach for conducting vulnerability assessment, including scenarios, assessment
methods, and results
• Discussion of application of vulnerability assessment information.
Individual utility case studies are presented in the following four chapters. To the extent
possible, the level of detail for the case studies is consistent. The final chapter of this report
presents summary observations and insights gained from these four case studies.
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2. EAST BAY MUNICIPAL UTILITY DISTRICT
East Bay Municipal Utility District (EBMUD) is a public water utility established in
1923 under the California Municipal Utility District Act. Within the EBMUD service area,
Special District Number 1 (SD1) was established in 1944 to treat wastewater.
2.1. BACKGROUND
EBMUD provides water to an estimated 1.3 million people in 35 communities in
Alameda and Contra Costa Counties in East San Francisco Bay, as well as industrial and
commercial water users (Wallis et al., 2008; EBMUD, 2009b). It produces an average of
220 million gallons per day (mgd) of drinking water in non-drought years. The total service area
9 _
is approximately 335 mi . EBMUD also provides wastewater services for approximately
640,000 customers west of Oakland/Berkeley Hills (EBMUD, 2009b) in an 83-mi2 component of
the EBMUD service area.
Diverse topography and maritime influences in California and the San Francisco Bay area
contribute to a varied climate within the EBMUD service area (Figure 2). The Coast Range runs
parallel to the coastline from Oregon to north of the Los Angeles Basin and is generally no more
than 50 miles wide (WRCC, 2010). A break in the Coast Range at San Francisco Bay allows the
inflow of marine air to the interior of the State under specific circulation patterns (WRCC, 2010).
The Coast Range merges with the Cascade Range in the northern part of the State creating a
200-mile-wide area of rugged terrain (WRCC, 2010). The Cascades then tend southeast and
merge into the Sierra Nevada, which continues to parallel the coast. Between these two ranges is
the Central Valley. This flat, 45-mile-wide valley is closed off by the meeting of the Sierra
Nevada and Tehachapi Mountains, which tend southwest to meet the Coast Range (WRCC,
2010).
West of these mountain ranges, the climate is predominantly maritime, dominated by the
Pacific Ocean. This area experiences warm winters, cool summers, small daily and seasonal
temperature ranges, and high relative humidity (WRCC, 2010). East of the mountain ranges, the
climate is continental desert, characterized by warmer summers, colder winters, greater daily and
seasonal temperature ranges, and generally lower relative humidity (WRCC, 2010). In the
transition zone between these two areas, climate depends on how the local topography influences
circulation patterns (WRCC, 2010). The difference between Oakland, California, on the San
Francisco Bay, and Livermore, California, just 30 miles inland, illustrates the climate variability
within the EBMUD service area. The average maximum July temperatures are 72°F and 89°F in
Oakland and Livermore, respectively (WRCC, 2010).
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Snowmelt from the Sierra Nevada feeds most major streams well into or throughout the
arid summer months. Dams serve a dual purpose of providing a water supply throughout the dry
part of the year and flood control during the winter and spring. In Oakland, the average total
precipitation is 23 inches per year, while in Livermore it is 14 inches per year (NCDC, 2010).
All of the precipitation in Oakland falls as rain while Livermore, on average, receives
approximately 0.1 inch of snow (NCDC, 2010) annually.
Climate change has been documented in this region. In the second half of the twentieth
century, a 3.6°F (2°C) rise in winter temperature was observed in the Sierra Nevada (EBMUD,
2009a). With a 9°F (5°C) rise in temperature, the April 1 snow-covered area could decrease by
as much as 50% (California Department of Water Resources [CA DWR] Report).
2.2. DESCRIPTION OF THE WATER SYSTEM
2.2.1. Drinking Water Supply System
2.2.1.1. Water Sources
The main water source for EBMUD is the Mokelumne River Watershed, which is located
approximately 100 miles northeast of the service area in the Sierra Nevada (Figure 2).
Approximately 90% of the water supply originates from this 577-mi2 area (Wallis et al., 2008).
The remaining water supply is from runoff in protected watershed areas of the East Bay into
terminal reservoirs. During dry years, evaporation from East Bay terminal reservoirs can exceed
runoff, resulting in no net water supply from local runoff in those years (EBMUD, 2009b).
Most of the Mokelumne River Watershed is undeveloped. Approximately 75% of the
watershed is forested and located within national forests. Precipitation is highly variable in the
watershed; 14 of the past 20 years have had below-normal precipitation or have been critically
dry. Precipitation also varies considerably by season, with most precipitation occurring from
November to May and the least from June to September. Peak flows take place during winter
storms and the spring snowmelt; minimum flows occur in the late summer and fall (EBMUD,
2009b). Approximately 63% of the annual average runoff happens during the spring snowmelt
from April to July (EBMUD, 2009a).
Two reservoirs on the Mokelumne River provide water storage, flood protection,
recreation, hydropower, and resource management for a downstream fish hatchery. Flow into
Pardee Reservoir is regulated by several upstream reservoirs. Pardee Reservoir has a maximum
storage capacity of 197,950 acre-feet. The Mokelumne Aqueducts (three closed-pipe aqueducts)
stretch 91 miles across the Sacramento/San Joaquin River Delta to convey water from the Pardee
Reservoir to the EBMUD service area. The remaining water from the Pardee Reservoir flows to
the Camanche Reservoir, which has a maximum storage capacity of 417,120 acre-feet. Water
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Figure 2. East Bay Municipal Utility District (EBMUD) service area and
ultimate service boundary.
Source: EBMUD (2009b).
from the Pardee Reservoir is used to meet the demands of the EBMUD service area, while the
Camanche Reservoir is managed to meet EBMUD's obligations to downstream fisheries and
senior water rights (EBMUD, 2009b).
EBMUD has water rights and capacity to use or divert to storage up to 325 mgd of water
from the Mokelumne River. The actual flow that can be diverted, however, is determined by the
amount of runoff and streamflow, upstream and downstream senior water rights, and storage
capacities. Additionally, the Camanche Reservoir must also provide releases for fisheries
downstream and ensure the availability of up to 200,000 acre-feet of flood control storage during
winter months (EBMUD, 2009b). Five terminal reservoirs have a combined capacity of
155,150 acre-feet (EBMUD, 2007). In addition to storing water from the Pardee Reservoir, the
terminal reservoirs in the East Bay capture runoff from protected areas of the East Bay
Watershed. The terminal reservoirs are operated to maintain 180 days of raw-water supply
(EBMUD, 2009b).
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Two additional water sources will be available starting mid-2010 to supplement water
supplies during dry years (Chan, 2010). Up to 100 mgd of raw surface water will be available
from the Sacramento River via the Freeport Regional Water Project. This additional water will
meet approximately 22% of the need during dry years. EBMUD estimates that it will use this
water source approximately 3 of every 10 years (EBMUD, 2009a). The other new source will be
from the first phase of the Bayside Groundwater Project. Treated drinking water from the
Mokelumne River will be injected into the south East Bay Plain Basin during wet years and
extracted during dry years. The withdrawal permit provides for up to an annual maximum of
1 mgd of water with an extraction rate of 2 mgd for a portion of a "particular drought year"
(EBMUD, 2009b).
2.2.1.2. Water Distribution
The water distribution system is composed of approximately 120 pressure zones (located
at elevations ranging from sea level to 1,450 ft) and approximately 4,100 miles of pipe. About
half of the water is distributed by gravity flow. In addition, there are approximately
140 pumping plants and 170 treated water storage tanks (EBMUD, 2007).
Water conveyed to EBMUD either is treated at one of three inline-filtration treatment
plants and distributed or is stored in the East Bay terminal reservoirs. Three additional drinking
water treatment plants are supplied by two terminal reservoirs. These three plants have full
conventional treatment, with two of them also providing ozonation.
2.2.1.3. Water Use
Water use in the EBMUD service area is approximately 92% residential, 7% commercial,
and 1% industrial and public authority use (EBMUD, 2007). Most water provision services are
funded by user fees (approximately 75%) with the remaining revenue coming from capital
contributions, investments, taxes, hydropower generation, and other sources (EBMUD, 2009c).
2.2.1.4. Demand Management
Programs for managing demand include water rationing, conservation, and reuse. In
calculating water availability, EBMUD follows its Water Supply Availability and Deficiency
Policy. According to this policy, the maximum rationing (i.e., mandatory water use reduction)
during droughts is a 25% reduction in total customer demand, while continuing to provide water
to fisheries and other downstream obligations (EBMUD, 2009b). Varying levels of rationing are
imposed, depending on the existing and projected extent of the drought and how the levels differ
across customer categories. Conservation measures include leak detection and repair in the
distribution system, customer incentives for water reduction, and customer education and
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outreach on water conservation. EBMUD reuses water by providing treated wastewater and
untreated raw water from local runoff for irrigation and in-plant processes (EBMUD, 2009b).
Approximately 9.3 mgd of water is recycled (Towey, 2010).
2.2.2. Wastewater System
EBMUD provides wastewater treatment in SD1, a subset of the water service area. Nine
communities within SD1 have wastewater collection systems that discharge into one of
EBMUD's five interceptor sewer trunk lines (EBMUD, 2010). The interceptors have a capacity
of 760 mgd of water. On average, the EBMUD wastewater treatment plant (WWTP) in Oakland
receives 80 mgd from the interceptors (EBMUD, 2007). The Oakland WWTP has the capacity
for 320 mgd of primary treatment, 168 mgd of secondary treatment, a short-term hydraulic peak
of 415 mgd during wet weather events, and 11 million gallons of storage (EBMUD, 2007;
Cheng, 2010). Treated wastewater is discharged 1 mile off the coast through a deep-water
outfall into San Francisco Bay (LAFCO, 2008; EBMUD, 2007).
By-products from WWTP operations are used in two forms: Biosolids are used as a soil
amendment or alternative daily cover at landfills, and methane gas provides energy needed for
operations (EBMUD, 2007). Additionally, as part of its wastewater source control and pollution
prevention activities, EBMUD collects concentrated domestic waste, oil, and grease from
restaurants, and other highly organic waste streams to produce methane gas, while decreasing the
organic content of the wastewater stream (EBMUD, 2007). Overall, self-produced methane gas
provides up to 90% of the Oakland WWTP's power supply (Cheng, 2010).
Since 1979, EBMUD and local communities have addressed rainwater infiltration and
inflow in the wastewater collections system resulting from deteriorated pipes and improper storm
drain connections. As part of the East Bay Infiltration/Inflow Correction Program, EBMUD
constructed three wet-weather treatment plants, two storage basins, 7.5 miles of new interceptor
lines, and an expanded Oakland WWTP. Communities have spent more than $460 million on
improvements for their wastewater collection systems (EBMUD, 2007).
In 2009, approximately 69% of the revenue for wastewater services came from user fees
(53% from wastewater, 16% from wet-weather facilities), and the remaining came from capital
contributions, resource recovery, taxes, investments, and other sources (EBMUD, 2009c).
2.3. CLIMATE CHANGE PROJECTIONS AND RISKS
The climate change information EBMUD used to evaluate vulnerability to climate
change included the Fourth Assessment Report of the Intergovernmental Panel on Climate
Change (IPCC, 2007) and two state-level studies that modeled the effects of climate change on
water resources (EBMUD, 2009a). Model projections from the IPCC suggest that temperatures
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in the western United States could rise 3.6-13.5°F (2.0-7.5°C) by the end of this century (IPCC,
2007, as cited in Wallis et al., 2008). In a summary of northern California climate change
studies, Dettinger (2004, as cited in EBMUD, 2009a) provides a range of a 3.6-10.8°F
(2.0-6.0°C) increase in temperature and either a 20% increase or decrease in precipitation.
Rising temperatures are expected to cause precipitation to fall more often as rain, decreasing
water storage in snowpack and causing spring runoff to occur earlier. The temperature rise will
extend the growing season by about 19-28 days, with more frequent and longer heat waves
(Wallis et al., 2008). Sea level is expected to rise another 0.6-1.9 ft by the end of the century
(IPCC, 2007, as cited in Wallis et al., 2008). This rise in sea level will affect the frequency and
severity of flooding in coastal areas, including the flood-prone Sacramento/San Joaquin River
Delta, which three EBMUD water transmission aqueducts cross (Wallis et al., 2008).
EBMUD reviewed two state-level climate change studies—one by the California Energy
Commission's Public Interest Energy Research (PIER) and the California Climate Change
Center (CCCC), and one by the California Department of Water Resources (CA DWR). A
review of both state-level studies by EBMUD concluded that the studies yielded the following
similar but uncertain results (EBMUD, 2009a):
• Temperature increases will be significant, but the magnitude of change is uncertain.
• Snowpack volume will decrease.
• Snow will melt earlier.
• The direction and amount of change in total annual precipitation are inconclusive.
• Drought impacts are inconclusive, but some scenarios predict increased frequency and
longer duration droughts.
• Climate variability will generally increase.
With a growing awareness of climate change and its potential effects on water resource
management, EBMUD started following climate change research, collecting information about
projected regional climate change, gathering environmental data, and networking locally and
nationally with others in the water community (Wallis et al., 2008; Chan, 2010). EBMUD staff
presented these efforts to the Board of Directors and at an annual business forum the Board of
Directors and key stakeholders attended (Wallis et al., 2008).
Additionally, EBMUD gauged customer opinion about climate change in an annual
customer survey. Of the respondents, almost 75% thought that climate change will be an issue
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for water suppliers within the next 50 years, and the effect of climate change on water
availability was of "highest concern" for 46% (Wallis et al., 2008; Chan, 2010).
In mid-2007, EBMUD established an official utility-wide management approach for
addressing climate change and formed a cross-departmental climate change committee. The
committee's primary tasks include keeping up to date on climate change science, evaluating the
potential effects of climate change, reviewing Mokelumne River Watershed data to determine
changes in trends, assessing water supply and infrastructure vulnerabilities, integrating climate
change in planning and budgeting, and developing adaptation and mitigation strategies. By
2008, the EBMUD strategic plan added climate change as one of the strategies for meeting
long-term water supply goals (EBMUD, 2008). Strategies included developing and
implementing a Climate Change Monitoring and Response Plan and mitigating greenhouse gas
emissions across departments (Wallis et al., 2008). While climate change-related activities, such
as mitigating greenhouse gas emissions are cross-departmental, vulnerability assessment efforts
have focused primarily on the water supply system (Cheng, 2010).
2.4. CLIMATE CHANGE VULNERABILITY ASSESSMENTS
EBMUD identified four key areas of potential vulnerability to climate change:
(1) flooding and sea level rise, (2) hydropower generation, (3) water supply and demand, and
(4) water quality (Wallis et al., 2008). Since 2006, EBMUD has conducted qualitative
assessments and sensitivity analyses to examine these vulnerabilities and their impacts on the
drinking water system. The most extensive and quantitative vulnerability analysis was
completed as part of the Water Supply Management Program (WSMP) 2040. Vulnerability
analyses for the WSMP 2040 focused on water supply, water demand, and the effect of
temperature on water quality. Qualitative and less formal assessments have been performed for
flooding, sea level rise, and power generation. EMBUD also participates in local and national
conferences and workgroups, such as the U.S. Environmental Protection Agency (EPA) Climate
Ready Water Utilities Working Group, and currently is working with the U.S. EPA and the
Water Research Foundation on developing vulnerability and risk assessment tools to assist other
water utilities in conducting climate change analyses (Chan, 2010). For more detailed
information on how EBMUD and other utilities organized their vulnerability assessments, see
Climate Change Vulnerability Assessments: A Review of Water Utility Practices (U.S. EPA,
2010).
2.4.1. Flooding and Sea Level Rise
EBMUD expects that flooding could increase as a result of the more frequent extreme
weather events that are predicted with climate change. To assess the effect of more extreme
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weather events on the potential for flooding in urbanized areas downstream of the Camanche
Reservoir, EBMUD modeled the water supply system with a 5.4°F (3°C) rise and 1997
precipitation levels (the wettest year in the past quarter century due to El Nino). The study used
the daily operational model for the EBMUD water system (Chan, 2010). Results showed that the
peak water release from the Camanche Reservoir would have had to be three times greater than it
was in 1997 to prevent riverine flooding (Wallis et al., 2008).
In addition to more extreme weather events, sea level rise could contribute to increased
coastal flooding. A 1-foot rise in sea level could cause the l-in-100-year storm surge flood event
to occur once every 10 years (Wallis et al., 2008). The aging levee system in the flood- and
earthquake-prone Sacramento/San Joaquin River Delta is an existing vulnerability that would be
exacerbated by rising sea levels. Such coastal flooding could disrupt water delivery for months
as it did in 2004, when a single levee breach caused flooding that submerged the aqueducts for
more than 4 months.
As part of WSMP 2040, EBMUD reviewed the two state-level climate change studies
(Section 2.3, above) and found that they sufficiently document current conditions and existing
risks, including the susceptibility of the raw-water system to levee failures, earthquakes, and
potential failure scenarios. The interactions of vulnerabilities, such as the effects of sea level rise
on levee failure, however, have not been characterized. CA DWR is drafting a Delta Risk
Management Strategy, and its first report will provide discrete probabilities of levee failure
considering several climate change and sea level-rise scenarios. EBMUD plans to use this
information to comment on improvement options CA DWR proposes (EBMUD, 2009b).
2.4.2. Hydropower Generation
Although extreme weather events could cause more intense precipitation and flooding,
total annual precipitation might decrease. Decreased annual precipitation would not only affect
the ability to meet water needs but also would affect hydropower generation. To model the
potential range of effects, EBMUDSEVI was used. EBMUDSEVI is a monthly time-step model of
the EBMUD water supply system from the Mokelumne River reservoirs to the five terminal
reservoirs in the service area, all of which are modeled as one combined reservoir (Chan, 2010).
Results suggested that the projected changes in total precipitation could lead to a
10-30% decrease in hydropower generation (Wallis et al., 2008).
2.4.3. Water Supply
EBMUD has had several ongoing activities related to climate change, but the first
extensive, quantitative analyses to assess the effects of climate change on its water supply system
were conducted for WSMP 2040. The main objective of WSMP 2040 was to identify and
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recommend a portfolio of projects for meeting customers' dry-year water needs through 2040.4
The process consisted of six steps: (1) identifying a list of projects that could provide additional
supply, (2) screening the projects, (3) developing portfolios of projects that satisfy water needs
through 2040, (4) screening 14 preliminary portfolios under historic hydrologic conditions with
existing drought planning sequence, (5) modeling five of these portfolios under the effects of
projected climate change, and (6) making a final portfolio selection. Projects included changes
in rationing, conservation, water reuse, surface water transfers, groundwater banking/exchange,
desalination, and enlargement of reservoir(s) (EBMUD, 2009b). Several uncertainties were
identified regarding the proposed projects, including institutional and legal challenges, undefined
timelines for project completion, and climate change. To reduce these uncertainties, a reliable
portfolio was defined as being (1) robust with respect to an uncertain future, (2) composed of
projects that can be pursued simultaneously, and (3) flexible and diverse (EBMUD, 2009c). To
inform the selection of a reliable portfolio, a climate change vulnerability analysis was
conducted.
EBMUD reviewed 10 other water agencies in California to determine how each was
assessing its vulnerabilities to climate change (EBMUD, 2009a). Based on this information,
EBMUD considered five approaches for evaluating the effects of climate change on the water
supply system: (1) qualitative analysis, (2) perturbing historic hydrology based on perturbation
factors from existing studies, (3) hydrologic modeling based on existing climate-derived
hydrology by other studies, (4) hydrologic modeling using climate-derived temperature and
historic precipitation, and (5) sensitivity analyses using historic hydrology in a hydrologic model
(EBMUD, 2009b). A "bottom-up" approach using sensitivity analyses was selected based on a
recommendation by Miller and Yates (2006). A bottom-up approach consists of identifying the
factors that most affect the system's reliability and testing that sensitivity to and performance
under expected changes in those factors (EBMUD, 2009b).
EBMUD identified the three most significant factors that affect the water supply system's
reliability in meeting the projected 2040 dry-year water needs: (1) greater-than-expected
customer demand, (2) shift in the timing of spring runoff, and (3) decreased volume of
precipitation and runoff. EBMUD modeled three sets of scenarios based on these three factors
with potential changes in each factor based on the existing regional climate change studies to
determine the effect of each factor on the performance of the existing system.5 Modeling
assumptions included using existing conservation and recycled water levels, existing drought
planning sequence, and a maximum of 25% rationing. The model was run from 1953 to 2002
4Existing supplies were estimated to be sufficient during normal and wet years.
5The existing system was composed of the existing components of the water supply system and projects that were
expected to be online by 2010 (i.e., Bayside groundwater and Freeport surface water, see Section 2.2.1).
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according to each of the three scenarios (EBMUD, 2009a). Although climate change projections
from the IPCC, PIER/CCCC, and CA DWR reports have significant uncertainties, they provided
an approximate range of potential changes in climate and hydrology. From this range, EBMUD
selected and modeled those changes that are expected to affect the utility's ability to provide
sufficient water and meet regulatory obligations for downstream water flow and temperature
(e.g., increases in precipitation were not modeled).
2.4.3.1. Temporal Shift in Runoff
As a result of increasing temperatures, the volume of runoff between April and July has
decreased by approximately 10% over the past century (Wallis et al., 2008). The sensitivity of
the water supply system to reductions in spring runoff and increased winter runoff was modeled
for 3.6°F, 5.4°F, and 7.2°F (2°C, 3°C, and 4°C) increases in temperature. The analysis estimated
the decrease in the volume of runoff from April through June and assumed an increase in the
November-to-March runoff by the same volume (EBMUD, 2009a). With 3.6°F, 5.4°F, and
7.2°F (2°C, 3°C, and 4°C) temperature increases, estimated reductions in April through June
runoff were 19%, 28%, and 38%, respectively. Carryover storage decreased by an average of
2.5-6% and a maximum of 10-16%. Customer rationing was estimated to increase by a
maximum of 7%. Flood control releases increased in 60% of the years between November and
May by an average of 66-89%. Between April and July, flood control releases decreased in 35%
of the years by 40-80% (EBMUD, 2009a).
The shifts in the timing of runoff had no significant impact on EBMUD's ability to meet
water demand because EBMUD's total reservoir storage is larger than the total annual average
runoff (EBMUD, 2009a). This capacity enables system operations to be reconfigured for fewer
flood control releases (Wallis et al., 2008). When considered in combination with the need to
adjust flood releases from the Camanche Reservoir to accommodate extreme precipitation events
as predicted above, however, the finding suggests a more delicate balance between flood control
and capturing the projected temporal shift in spring runoff.
2.4.3.2. Decrease in Annual Precipitation
The effect of reduced precipitation was assessed by assuming that reductions of 10% and
20% in the volumes of annual precipitation directly correspond to 10% and 20% decreases in
runoff. Both scenarios were run in the W-E model, a linked combination of the Water
Evaluation and Planning and EBMUDSJJVI models, which resulted in the most significant effects
observed among all the scenarios. For the 10% and 20% reductions in precipitation, the average
decreases in carryover storage were 12% and 24%, respectively, and the maximum decreases
were 47% and 76%, respectively. The magnitude of customer rationing increased on average by
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3.8% and 6.4% for the 10% and 20% decreases in precipitation, respectively. The frequency of
rationing increased from a baseline of 36% to 44% and 52%, respectively, for the 10% and 20%
decreases in precipitation. Average annual flood releases decreased by 43% and 74% for the
10% and 20% decreases in precipitation, respectively (EBMUD, 2009a).
In comparison, the worst drought on record occurred in 1976 and 1977 and resulted in a
75% decrease in average runoff and a 70% reduction in total reservoir capacity (EBMUD,
2009a). A limitation of these sensitivity analyses is that the change in each vulnerability factor
was modeled individually, and the synergistic effect of a simultaneous change in all three factors
at same time was not considered (EBMUD, 2009b). A final scenario with all three factors would
have provided insight into the worst-case scenario.
2.4.3.3. Increased Demand
To test the effects of increased water demand, 2040 water demand estimates were
recalculated assuming a 7.2°F (4°C) increase in air temperature, resulting in a 3.6% increase in
demand.6 The higher demand estimate accounts for higher consumptive use for drinking and
outdoor watering due to higher temperatures alone. A 20% decrease in precipitation had
relatively little effect on demands compared to the temperature increase. Therefore, only the
demand estimate based on a temperature increase was run in the W-E model. Results showed an
average decrease in carryover storage of 3%, with a maximum decrease of 8%. Carryover
storage is significant for the EBMUD water supply system, because the reservoirs do not
necessarily refill each year, depending on drought conditions. The results also indicate that the
magnitude of customer rationing increased to a maximum of 5.6% of demand, but the frequency
with which rationing occurred did not change. Flood control releases were not evaluated in this
analysis (EBMUD, 2009a).
2.4.4. Water Quality
EBMUD used the Watershed Analysis Risk Management Framework (WARMF) model
to assess the effect of increasing air temperatures on water temperatures. The WARMF model
was developed by the Upper Mokelumne River Watershed Authority for a different study in
which EBMUD participated. This previous analysis was completed to determine the effect of
climate change on EBMUD's continued ability to meet its cold-water obligations to the
downstream fish hatchery (EBMUD, 2009a).
Six water years were modeled, including two dry years, three below-normal years, and
one above-normal year. Each year was modeled for increases of 3.6°F, 5.4°F, and 7.2°F (2°C,
6The 4°C change is based on projected increases from 1980 to 2040 or 2.15°C from 2005 to 2040.
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3°C, and 4°C) rise in air temperature projected to occur from 1980 to 2040. Over all scenarios,
average annual water temperatures increased by 0.5-6.3°F (0.3-3.5°C) relative to baseline
temperatures. In general, the effect of increasing temperatures was found to depend on the type
of hydrologic year and the season. In drier years and during the summer months, streamflow is
lower and air temperatures have a greater effect on water temperatures (EBMUD, 2009a).
EBMUD studies also identified other water quality effects from climate change,
including a greater potential for algal growth with higher water temperatures. In addition, with
increasing intensity and frequency of storm events, turbidity levels can increase in water supply
sources. Because the EBMUD drinking water treatment plants were designed for treating source
water that is low in turbidity, increases in turbidity could decrease the plants' daily outputs and
increase treatment costs (Wallis et al., 2008).
2.5. APPLICATION OF VULNERABILITY ASSESSMENT INFORMATION
Several key insights were provided by the climate change analyses described above for
the WSMP 2040 decision-making process. The analyses showed a clear distinction between the
effects of temporal shifts in precipitation and a decrease in total annual precipitation. The
temporal shifts could be managed by adjusting system operations, while decreased precipitation
would require additional sources of water outside of the Mokelumne River Watershed. Before
conducting these studies, EBMUD believed that diversification of water supply sources was
needed. The studies reaffirmed the need for diversifying water supply sources outside of the
watershed and selecting projects that can be adapted as climate change effects are observed. For
example, instead of relying solely on enlarging existing reservoirs, EBMUD will pursue
additional surface water and groundwater sources. Plans also will be drawn up for regional
desalination. To meet the 2040 dry-year water needs, conservation, desalination, and the
enlargement of reservoirs in combination with groundwater banking and exchange are needed.
Pursuing parallel tracks on alternative projects will allow for flexibility, not only with regulatory
and logistical challenges, but also with adjusting to future refinements of climate change
projections. Although water quality vulnerabilities were not directly addressed, the analyses
revealed that the interaction of lower water levels in the reservoirs and increased air temperatures
are causal factors for potential water quality concerns.
To support continued climate change vulnerability assessments and adaptation activities,
EBMUD identified two main resources that would support these efforts: (1) information on the
probabilities of specific projected changes in temperature and precipitation, and (2) a common
source for region-specific environmental data to assist in vulnerability analyses (Chan, 2010).
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3. NEW YORK CITY DEPARTMENT OF ENVIRONMENTAL PROTECTION
3.1. BACKGROUND
New York City's Department of Environmental Protection (DEP) is responsible for the
operation, protection, and maintenance of New York City's drinking water system (DEP, 2010a).
DEP supplies 1.1 billion gallons per day (gpd) of drinking water to 8.2 million residents of New
York City, and an additional 1 million people in nearby municipalities (DEP, 2008a; see
Figure 3). DEP supplies approximately 85% of the water for Westchester County and 5-10% of
the water for Orange, Putnam, and Ulster Counties (Rosenzweig et al., 2007). The system also
provides legally mandated conservation releases to the Delaware River Basin (DEP, 2008a).
New York State experiences a humid continental climate but with dramatic variations
from that climate type due to latitude, general circulation patterns, and topography. Although the
region is located along the coast, the area is dominated by drier continental airflow from the
prevailing westerly winds. The state's climate is conditioned primarily by cold, dry air masses
from the northern continental interior, as well as warm, humid air masses from the south
conditioned by the Gulf of Mexico. A third, but relatively less important influence is the air
mass from the North Atlantic Ocean, which can produce cool, cloudy, and damp weather. Due
to the prevailing winds, however, this maritime influence is secondary to the more prevalent
airflow from the continental interior (New York State Climate Office, 2010).
Average annual temperature is approximately 55°F in New York City but 10-15°F cooler
in the Catskills, which is the major source of water. The distribution of precipitation across New
York State is influenced by topography and proximity to the Great Lakes and Atlantic Ocean.
Average annual precipitation can exceed 50 inches in the Catskills. In New York City, average
annual precipitation is 43-50 inches per year, depending on location within the city.
Precipitation is relatively evenly distributed throughout the year, and no distinctly wet or dry
seasons occur (NYC Panel on Climate Change, 2009; New York State Climate Office, 2010).
In the mountainous areas of New York State, such as the Catskills, annual average
snowfalls range from 70-90 inches, but topography and elevation cause snowfall over even short
distances in the state's interior to vary greatly. The bulk of wintertime precipitation in these
areas falls as snow. New York City, however, receives only about 25-35 inches of snow per
year due to the moderating influence of the Atlantic Ocean. Because of the temperature
modulation of the coastal zone, only about one-third of the winter-season precipitation is
associated with storms having snow accumulation of at least 1 inch (New York State Climate
Office, 2010); the rest falls as rain.
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City Tunnel No. 3
City Tunnel No. 1
Figure 3. New York City Department of Environmental Protection (DEP)
system overview.
Source: DEP (2008b).
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Annual mean temperature in New York City has increased 2.5°F since 1900, although
both warming and cooling periods occurred over this time. Mean annual precipitation levels
have increased only slightly since 1900, but year-to-year variability in precipitation has increased
(NYC Panel on Climate Change, 2009).
3.2. DESCRIPTION OF THE WATER SYSTEM
3.2.1. Water Supply System
New York City's surface water is supplied from a network of 19 reservoirs and
r\
three controlled lakes in a region that stretches nearly 2,000 mi and extends 125 mi north of the
City (Figure 3). This region is divided into two geographically discrete systems—the
Catskill/Delaware reservoir systems, located in upstate New York, well north and west of the
City and the Hudson River, and the Croton Reservoir system, which is located north of the City
and east of the Hudson River. Some (less than 1%) of New York City's water is obtained from
the Brooklyn-Queens Aquifer, located in southeastern Queens (DEP, 2008b).
The Catskill/Delaware reservoir systems provide approximately 90% of New York City's
water. The Catskill Water Supply System was completed in 1927, and the Delaware Water
9 _
Supply System in 1967. Together, these watersheds cover roughly 1,600 mi (U.S. EPA, 2009b).
Forests cover approximately 75% of the watersheds. More than 20,000 private landowners own
an estimated 75% of the forested land area (Brunette and Germain, 2003).
In 1993, New York City began implementing watershed protection programs to reduce
the susceptibility of the surface water supply to contaminants. In 1997, The U.S. Environmental
Protection Agency (EPA) partnered with the State of New York, the City of New York, and
some 80 watershed municipalities and environmental groups to forge the New York City
Watershed Memorandum of Agreement (MOA). This MOA set forth a set of conditions that the
City had to meet for U.S. EPA to issue a 5-year Filtration Avoidance Determination (FAD).
This FAD allows DEP to avoid filtering its Catskill/Delaware drinking water by establishing a
land acquisition program for source water protection, by setting more stringent New York City
watershed rules and regulations, and by implementing other watershed protection strategies.
U.S. EPA reissued New York City a 5-year FAD in 2002 and a 10-year FAD in 2007. The New
York State Department of Health and the U.S. EPA monitor these ongoing source water quality
programs. Projects include
• Land Acquisition—New York City buys property from willing sellers to buffer the
reservoirs and controlled lakes.
• Land Management—DEP develops land management programs.
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Partnership Programs—DEP partners with many local organizations to help protect
source water quality, for example, by improving septic systems.
Wastewater Treatment Plant Upgrades—New York City funds improvements to
non-city-owned wastewater treatment plants for communities in the source watersheds.
Stream Management Programs—DEP supports partnerships to stabilize streams in the
area.
Watershed Agricultural Programs and Forestry Program—These programs work with
farms to help implement best management practices that reduce agricultural pollution and
protect water quality (DEP, 2008b).
Glacial clay deposits underlay stream channels and steep topography surrounds the
waterways in the Catskill water system. As a result, the system is prone to high turbidity due to
intense precipitation events and associated runoff. Maintaining the FAD for the Catskill and
Delaware water supplies is a crucial element to future watershed plans. To meet FAD-required
standards, DEP has occasionally added alum to the waters entering Kensico Reservoir to reduce
turbidity.7 Periodically, the alum and associated sediment must be dredged from the reservoirs
(DEP, 2005).
The Croton Watershed contains three upland reservoirs which supply approximately 10%
of the City's water. It covers roughly 375 mi2 east of the Hudson River in Westchester, Putnam,
and Dutchess Counties and a small section of Connecticut. The Croton system began service in
the mid-1800s and was completed before World War I (Rosenzweig et al., 2007). Since the
1950s, the Croton Watershed has developed quickly with the construction of 60 wastewater
treatment plants, interstate highways, residential developments, and impervious surfaces (New
York Water, 2010). On several occasions, the Croton Watershed has been contaminated as a
result of stormwater runoff.
For example, 12 of Westchester county's 45 municipalities lie within the boundaries of
the Croton Watershed. These municipalities contribute to water supply contamination as a result
of lawn-care chemical use, automobile use, combined sewer system overflows, and other human
factors, as well as reduced infiltration of precipitation that flows through urban drainage
infrastructure. In 1993, the U.S. EPA determined that the Croton system failed to meet the
requirements of the Surface Water Treatment Rule, and Croton system raw water would need to
be filtered and disinfected. Repeated violations of turbidity and disinfectant by-product rules
under the 1996 Safe Drinking Water Act Amendments have caused DEP to periodically remove
7Alum serves as a coagulant, precipitating suspended solids from raw water, reducing objectionable color and
turbidity.
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the Croton system from service (Water-Technology.net, 2010; DEP, 201 Ob). After several
delays and consent orders resulting in fines, the first phase of construction of the Croton
raw-water treatment plant began in 2006 and is expected to be operational by 2012. Treatment
will include a pretreatment stage, mixing and coagulation, flocculation, chemical balancing,
stacked dissolved air floatation, and ultraviolet and chlorine treatment. The filtration plant is
expected to improve water quality by reducing turbidity, decreasing the risk of microbiological
contamination, and reducing the levels of disinfection by-products (DEP, 2008b). Communities
around the Croton Watershed also signed the 1997 MOA aimed at improving watershed
protection. They are participating in land acquisition and other raw water quality projects, as
discussed above (DEP, 2008b).
3.2.2. Wastewater System
DEP is also responsible for operating, protecting, and maintaining New York City's
wastewater system. The wastewater network includes more than 6,000 mi of wastewater pipes,
135,000 sewer catch basins, 495 permitted outfalls, 95 wastewater pumping stations, and
14 wastewater treatment plants spread across the City's 5 boroughs (DEP Web site). On
average, the system treats 1.4 billion gpd of wastewater and has the capacity to treat dry-weather
flows of 1.8 billion gpd (DEP, 2006).
New York City's wastewater undergoes five major processes: preliminary treatment,
primary treatment, secondary treatment, disinfection, and sludge treatment. Approximately 60%
of the City's sewers are combined, making combined sewer overflows (CSOs) a continuing
problem for DEP (DEP, 2008a) during intense precipitation events. Violations of New York
City's 1988 State Pollutant Discharge Elimination System permit led to a 1992 consent order
between New York State's Department of Environmental Conservation and DEP, requiring a
CSO abatement program. A 2004 consent order with more detailed guidance includes
requirements for more than 30 citywide projects, such as sewer separation, flushing tunnels,
off-line retention tanks, and vortex concentrators to improve the efficiency of the wastewater
system (NYSDEC, 2010). While continuing to invest in traditional, or grey, infrastructure, the
City is implementing measures to maximize the use of green infrastructure and other source
controls to reduce stormwater runoff from new and existing development. Unveiled in
September 2010 and subject to regulatory negotiations and approvals, the NYC Green
Infrastructure Plan marks a departure from conventional and expensive approaches to stormwater
management.
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3.3. CLIMATE CHANGE PROJECTIONS AND RISKS
DEP expects temperatures in New York City and its watersheds to increase by 1.5-3°F
by the 2020s, 3-5°F by the 2050s, and 4-7.5°F by the 2080s (Table 2). The variability in
precipitation in the New York City area is large. Most climate model projections indicate small
increases in precipitation, but some suggest precipitation decreases, thus reducing confidence in
projections of precipitation in this region. The New York City Panel on Climate Change
concluded in 2009 that the best estimates at this time indicate approximate increases of 0-5% by
the 2020s, 0-10% by the 2050s, and 5-10% by the 2080s. Most models indicate precipitation
increases for the winter months and slight decreases during September and October.
Furthermore, as temperatures increase, more precipitation is expected to fall as rain instead of
snow (NYC Panel on Climate Change, 2009). In short, the observed climate change trends are
projected to continue and, in some cases, accelerate.
Table 2. Projected baseline climate and mean annual changes for
New York City
Climate indicators
Air temperature (°F)
Precipitation
Sea level rise (inches)
Number of days/year with max temp.
above 90°F
Number of days/year with max temp.
above 100°F
Number of heat waves/year
Number of days/year with rainfall
exceeding 1 inches
Number of days/year with rainfall
exceeding 2 inches
Number of days/year with rainfall
exceeding 4 inches
Baseline
1971-2000
55
46.5 in
N/A
14
0.4
2
13
3
0.3
2020s
+1.5-3
+0-5%
+2-5
23-29
0.6-1
3-4
13-14
3-4
0.2-0.4
2050s
+3-5
+0-10%
+7-12
29-45
1-4
4-6
13-15
3-4
0.3-0.4
2080s
+4-7.5
+5-10%
+12-23
37-64
2-9
5-8
14-16
4-4
0.3-0.5
Source: NYC Panel on Climate Change (2009, pp.17, 20).
New York City has taken a proactive approach to climate change. In 2001, the City
joined the Local Governments for Sustainability's Cities for Climate Protection campaign. In
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2004, DEP created a climate change task force to assess the potential impacts of climate change
on the City's water infrastructure. The task force comprises representatives from a variety of
DEP's offices and initially included participants from Columbia University's Center for Climate
Systems Research, the National Aeronautics and Space Administration's Goddard Institute for
Space Studies, HydroQual Environmental Engineers and Scientists, P.C., the New York City
Office of Environmental Coordination, the Mayor's Office of Long-term Planning and
Sustainability, and the New York City Law Department. The task force created an action plan,
which includes the following tasks (DEP, 2008a):
• Work with climate scientists to improve regional climate change projections
• Enhance DEP's understanding of the potential impacts of climate change on DEP's
operations
• Determine and implement appropriate adaptations to DEP's water systems
• Inventory and manage greenhouse gas emissions
• Improve communications and tracking mechanisms.
A sustainability plan for New York City, PlaNYC, was unveiled on Earth Day in 2007.
The plan outlines a 25-year vision for the city, focusing on maintaining and improving the City's
infrastructure centering on land, water, transportation, energy, air, and climate change. PlaNYC
has set an ambitious target to reduce the City's greenhouse gas emissions by 30%. New York
City's plan for climate change adaptation includes (1) creating an intergovernmental task force to
protect the City's infrastructure, (2) working with vulnerable neighborhoods to develop
site-specific plans, and (3) launching a citywide strategic planning process (PlaNYC, 2007a;
PlaNYC, 2007b; PlaNYC, 2008-2010).
To respond to climate change in New York City and to meet the goals established in
PlaNYC, the New York City Panel on Climate Change (NPCC) was created in 2008. This panel
is composed of climate change scientists and legal, insurance, and risk management experts.
With funding from the Rockefeller Foundation, NPCC has been charged with serving as the
technical advisory body for the Mayor and the New York City Climate Change Adaptation Task
Force. This organization has provided the Climate Change Adaptation Task Force with the most
comprehensive set of climate data that has been produced for New York City (NYC Panel on
Climate Change, 2009). Several experts engaged to assist DEP in 2004 also were enlisted to
assist NPCC in citywide planning efforts. DEP continues to pursue complementary climate
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change research because it is concerned with climate change in upstate New York (where the
Catskill and Delaware reservoir systems are located) and in the City itself.
3.4. CLIMATE CHANGE VULNERABILITY ASSESSMENTS
DEP's vulnerability work is based on three core questions of interest to DEP, including
the potential effects of climate change on (1) total water supply, (2) turbidity, and
(3) eutrophication (Barsugli et al., 2009). DEP worked with researchers from Columbia
University's Center for Climate Systems Research to design its Climate Impact Assessment
project (Major et al., 2007). The goal of this integrated modeling project is to estimate the effect
of future climate change on the quantity and quality of New York City's water supply. The
project will use climate change projections, DEP water quality and water supply models, and
analytical measures of system performance to advance DEP's understanding of the potential
impacts of climate change on the water supply system. For more detailed information on how
DEP and other utilities organized their vulnerability assessments, see the U.S. EPA report,
Climate Change Vulnerability Assessments: A Review of Water Utility Practices (U.S. EPA,
2010).
The project was planned in two phases. Phase I, now completed under contract with
Columbia University and the City University of New York (CUNY), is aimed to provide a
first-cut evaluation of the effects of climate change on water quantity and quality in selected
portions of the water system, using the existing modeling system and data available from
three general circulation models (GCMs). Phase II, now in process with continued support from
CUNY, has goals similar to those of Phase I but with upgrades to both models and data sets
applied to the entire water supply system, including a greater variety of GCM data and an
evaluation and application of differing downscaling methods. The Phase I effort used the
Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report (DEP, 2008a;
McCarthy et al., 2001), but current efforts have upgraded models and data that were used in the
IPCC Fourth Assessment Report (Parry et al., 2007).
A climate change scenario framework was developed for the New York City water
supply system using high temporal resolution data from the Program for Climate Model
Diagnosis and Intercomparison (PCMDI) Web site maintained by the Lawrence Livermore
National Laboratory in Berkeley, California (Maurer et al., 2007). Data for Phase I were
extracted from the single grid box at the center of the watershed region. Baseline data for
1981-2000 came from "hindcast" model runs. Data for 2046-2065 and 2081-2100 came from
three GCMs (the Goddard Institute for Space Studies [GISS] Model, the Max Planck Institute
[MPI] ECHAM5, and the National Center for Atmospheric Research [NCAR] CCSM3) coupled
with three scenarios from the IPCC Special Report on Emissions Scenarios: A1B, A2, andBl.
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The data included mean temperature, maximum temperature, minimum temperature,
precipitation, sea level pressure, zonal wind, meridional wind, solar radiation, longwave
radiation, and dewpoint temperature.
For Phase I, each scenario was used to calculate delta change coefficients representing
mean monthly change in air temperature and precipitation between control and future prediction
periods. Monthly delta change factors were applied additively for air temperature and as a ratio
for precipitation to historical meteorological period data, generating a future prediction time
series. The feasibility of applying the delta change method to the wind and solar radiation data
needed for the reservoir models was also investigated.
For Phase II, GCM selection included the entire CMIP3 multi-model data set, the A2,
A1B, and Bl emissions scenarios, and seven meteorological variables (precipitation; maximum,
minimum, and average temperatures; zonal and meridional winds; and solar radiation). Data
from all the GCMs were re-gridded to 2.5° corresponding to the Eastern North America region
using bilinear interpolation and the NCAR Command Language (NCL: www.ncl.ucar.edu). The
various levels of data processing involved necessitated that some data be eliminated from the
study depending on the number of models that contain a given meteorological parameter, the
number of runs archived for each GCM, and whether data existed for all points necessary in the
re-gridding process. GCM hindcasts were compared to historical data sets at four spatial scales:
Eastern North America, the nine grid points surrounding West of Hudson watersheds, the four
grid points surrounding New York City, and the single grid point closest to the centroid of New
York City watersheds. To develop a skill ranking and probability distribution function for each
meteorological variable, spatial scale, season (December to February, March to May, June to
August, and September to November), and GCM, the fidelity of hindcast values to observed
historical data was calculated.
The system of models that will be used for the integrated modeling project include the
General Watershed Loading Function (GWLF) and Soil Water Assessment Tool (SWAT)
watershed models, a one-dimensional reservoir eutrophication model, a two-dimensional
reservoir turbidity transport model (CEQUAL-W2), and the OASIS system operations model for
the entire water supply. These models taken together with the existing and in-process climate
scenarios make the proposed integrated assessment possible.
As the project progresses, further model enhancements and integration will be
implemented. For the GWLF watershed model, improvements will be made to the following
model elements: hydrologic balance, sediment and nutrient generation and transport, ecosystem
effects, and land use. For the reservoir models, additional upgrades and calibration and
development of response function models keyed on system performance measures will be
implemented. For the integrated system, enhanced coupling of the watershed and reservoir
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models to OASIS will be undertaken. And for model inputs, enhancements will include
advanced delta change with historical data morphing, statistical downscaling, and regional
climate model (RCM) simulations.
Several performance measures related to water system quantity and quality will be
developed and used to estimate climate change effects, including total water quantity,
probabilities of refill, probabilities of drawdown, key point turbidity levels, frequency of alum
use, reservoir phosphorus and chlorophyll concentrations, and restrictions in water use due to
eutrophi cation. DEP expects the results of this project to provide the basis for recommendations
about system operation now and in the future, and, in later phases, recommendations about
required infrastructure changes and improvements.
In 2009, the NPCC published its first report, Climate Risk Information. This report
provides climate change projections for New York City as a whole (not just DEP) and identifies
potential risks to the City's critical infrastructure. The projects presented in the model were
compiled using model-based probability functions. The NPCC used IPCC methods to calculate
changes in temperature, precipitation, and sea level rise from global climate model simulations
based on three greenhouse gas emission scenarios (A1B, A2, Bl). The NPCC used 16 GCMs to
generate possible changes in temperature and precipitation. Only seven GCMs were used for sea
level rise, as sea level rise is not a direct output of most GCMs. The generated sea level rise
values for the New York City area include both global and local components.
According to the NPCC report, changes in mean climate and climate extremes could
affect many aspects of New York City's water infrastructure. The potential wastewater and
drinking water impacts of the projected air temperature change include decreased water quality
due to biological and chemical impacts; increased water demand due to a longer growing season;
decreased snowpack, which could reduce inflows to reservoirs during the spring thawing season;
changes in the ecology of streams due to higher stream temperature, which could limit the
amount of water that can be extracted; and increased water demand. The biological and
chemical reactions in wastewater treatment plants also could be disrupted at higher temperatures
(DEP, 2008a).
Impacts related to the potential changes in precipitation include decreased average
reservoir storage, increased turbidity, increased nutrient loads, eutrophi cation, taste and odor
problems, and increased loading of pathogenic bacteria and parasites in reservoirs. Impacts of
potential precipitation changes on the wastewater system include increased probability of sewer
flooding and increased CSO events.
The potential impacts of sea level rise for city water resources include intrusion of the
salt front farther up the Hudson River (NASA, 1999), increased probability of seawater entering
sewers, reduced ability of wastewater treatment plants to discharge treated water by gravity
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alone, increased risk of CSO events, and increased coastal flood risk for low-elevation
infrastructure and wastewater treatment plants (NYC Panel on Climate Change, 2009; DEP,
2008a).
3.5. APPLICATION OF VULNERABILITY ASSESSMENT INFORMATION
DEP has conducted a suite of modeling studies to understand the vulnerability of its
systems to climate change, and has made decisions to reduce that vulnerability. This situation,
however, might be a case where analysis and policy, although informing each other, are
proceeding in parallel. New York City's climate change work has led to increased consideration
of climate change in strategic planning, has altered operations and maintenance practices, and
has changed future infrastructure planning and design. Many of these changes are not the direct
result of the New York City vulnerability assessments. Rather, they are part of a larger effort to
improve the resiliency and redundancy of water infrastructure in the face of existing
vulnerabilities that could be exacerbated by climate change. These decisions largely focus on
so-called "no-regrets" opportunities, or changes to the water supply system that make sense
regardless of whether or how climate changes. Some of these policy choices have been forced
by regulatory mandates, such as the development of a filtration plant for the Croton Watershed,
but others have significant benefits system wide, such as reducing leakage from aging supply
infrastructure.
PlaNYC and DEP's Climate Change Task Force have identified several initiatives that
aim to efficiently and effectively upgrade the city's drinking and wastewater systems in the face
of a changing climate. Proposed initiatives are discussed in detail below.
3.5.1. Decreasing Turbidity
Turbidity is a significant drinking water concern in the Catskill and Delaware Water
Systems. DEP has addressed this issue historically by adding alum as an "end-of-pipe" solution
and engaging in source-water protection measures. Projected increases in intense precipitation
events under climate change will most likely increase the turbidity of watersheds beyond historic
levels. New York City is continuing its historic programs to address this issue. In the future,
DEP will address potential turbidity challenges in the Catskill and Delaware Water Systems by
relying more heavily on the soon-to-be-filtered Croton system, a proposed interconnection
between the Catskill and Delaware Aqueducts, and operational modifications in how DEP uses
the Delaware and Catskill Water Systems during heavy precipitation or turbidity events.
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3.5.2. Minimizing Flooding
To minimize urban drainage flooding in New York City during the predicted increased
severe weather events, the Climate Change Task Force proposed more frequent cleaning of
sewers and maintaining catch basins in flood-prone areas. The task force also promoted green
roofs and the reuse of stormwater for "ecologically productive purposes." Green infrastructure
has become a significant component of DEP's proposed policies, especially for stormwater
management to reduce CSOs (PlaNYC, 2008; NYC Green Infrastructure Plan, 2010).
For example, New York City is planning to expand the Staten Island Bluebell program,
which was created as a natural system to prevent coastal and urban drainage flooding and septic
tank failure. It functions by diverting water from wastewater treatment to natural systems.
Nearly 36% of Staten Island's precipitation is diverted to a 10,000-acre Bluebell area. The
Bluebell program has saved the city an estimated $80 million in infrastructure development
(Rosenzweig et al., 2007). As severe weather events increase, the Bluebell and further
expansions will acl as nalural buffers, reducing pressure on Ihe waslewaler system and reducing
flooding issues and CSOs (PlaNYC, 2008).
3.5.3. Minimizing Supply and Demand Imbalances
Higher air temperatures increase peak water demand. Wilhin New York Cily, annual
average demand is approximately 1,069 mgd. During heal waves, demand can increase lo more
lhan 2,000 mgd. To minimize supply and demand imbalances, Ihe Climate Change Task Force
has slressed Ihe importance of slruclural improvemenls, such as reducing water pressure
problems and leakage. Small-scale conservation efforts also can reduce water demand (DEP,
2008a).
New York Cily has reduced water demand since 1985 Ihrough a variety of conservation
efforts, including education, metering, water-use regulation, leak detection, installation of
magnetic-locking hydranls, and rebate programs. These conservation efforts reduced water
consumption from 195 gpd per capila in 1991 lo 167 gpd per capila in 1998, wilh coincidenl
substantial cosl savings for bolh DEP and ils customers (U.S. EPA, 2002). Reducing water
demand also limils Ihe amounl of water entering Ihe waslewaler system and, Ihus, slress on Ihe
system. Wilh Ihe above conservation measures, Ihe volume of generated waslewaler decreased
by 200 mgd belween 1996 and 2006 (DEP, 2006).
Additionally, lo ensure sufficienl water quantity even in the face of higher temperalures,
DEP is evaluating new water sources Ihroughoul New York Cily and upslream watersheds.
These sources include groundwaler and new infraslruclure, such as potentially increasing the
capacity of the Catskill Aqueduct
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3.5.4. Decreasing Combined Sewer Overflows
To decrease CSO events caused by increased precipitation and intense precipitation
events, DEP has begun plans to upgrade wastewater treatment capacity, construct additional
holding tanks to increase wet-weather holding capacity, and optimize sewer infrastructure to
limit releases. New York City is also planning to convert some of the combined sewer systems
into high-level sewer systems,8 which divert a large percentage of the storm water directly to
waterways rather than into treatment plants. This strategy not only decreases the likelihood of
CSO events but also reduces costs by avoiding unnecessary water treatment. The Climate
Change Task Force also has proposed increasing pipe size to increase flow in areas where
possible (PlaNYC, 2008). In September 2010, DEP released the NYC Green Infrastructure Plan,
an adaptive management strategy for reducing CSOs using green infrastructure, grey
infrastructure, system optimization, and water conservation.
3.5.5. Adapting to Flood Risk
DEP is also considering converting water storage reservoirs for use as both water supply
and riverine flood control (DEP, 2005). To prevent critical assets from being disabled during
flood events, the DEP Climate Change Task Force has proposed moving key assets above
projected flood heights, installing watertight doors around crucial equipment, switching to
submersible pumps, and creating protective barriers such as sea walls, dunes, or tidal gates
around important assets (DEP, 2008a).
DEP will institute a snowpack-based reservoir management program to provide enhanced
riverine flood attenuation downstream. Under this program, Schoharie Reservoir would be
sustained below full capacity during the winter months when sufficient snowpack is present in its
watershed so that associated runoff produced by spring snowmelt could refill the reservoir to full
storage capacity. The capture of inflows associated with spring storm events and snowmelt
runoff in the reservoir would provide additional attenuation in downstream sections. The
temporary reservoir level targeted during the snowpack-based reservoir management period
would be regularly adjusted based on snow-water equivalent estimates of the watershed's
regularly monitored snowpack. As the name implies, snow-water equivalent is the water depth
equivalent of a given depth of snow and depends on such factors as the water content and density
of the snowpack (DEP, 2008c).
8High-level storm sewers alleviate pressure on the combined sewer system by capturing about 50% of the rainfall
before it enters combined sewer pipes and diverting it directly into waterways. Because such systems require a
separate pipe and outlet to a water body, they are generally cost-effective only near the water's edge.
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4. SEATTLE PUBLIC UTILITIES
4.1. BACKGROUND
Seattle Public Utilities (SPU) was formed in 1997 as a combination of the Drainage and
Wastewater Utility, Solid Waste Utility, the former Seattle Water Department, and portions of
Seattle City Light and the Seattle Engineering Department. This case study focuses on SPU
functions related to supplying drinking water to the City of Seattle, Washington. SPU's drainage
and wastewater system are mentioned only briefly.
SPU provides drinking water to a population of more than 1.35 million people in Seattle
and surrounding suburban areas. SPU provides direct retail water service to about
630,000 people primarily in the City of Seattle, parts of Shoreline, and small areas just south of
the city limits. SPU also sells water wholesale to 25 neighboring cities and water districts
serving another 720,000 people. SPU supplied 45.1 billion gallons of drinking water in 2008
from two Cascade Mountain watersheds supplemented with groundwater wells.
The Pacific Northwest climate is dominated by large spatial and temporal variations in
precipitation due to maritime influences and extreme topographical variation between the coast
and the Cascade Mountains. The low-lying valleys west of the Cascades, including the SPU
service area, are characterized by mild temperatures year round, wet winters, and dry summers.
Average annual precipitation for the Seattle area is about 37 inches, but in the mountains, that
total exceeds 100 inches. About 75% of Seattle area precipitation falls between October and
March (Miller and Yates, 2006). The SPU water supply system therefore also must be managed
for riverine floods. Typically, early winter precipitation fills reservoirs, which are allowed to
spill in anticipation of snowmelt combined with normally rainy springs, which refill reservoirs
for the dry summer months.
The regional climate fluctuations known as the El Nino Southern Oscillation (ENSO) and
the Pacific Decadal Oscillation (PDO) also strongly affect the Pacific Northwest. ENSO, PDO,
and the winter and spring climate of the region are highly correlated, enabling predictions of
Pacific Northwest precipitation, snowpack, and streamflow. The University of Washington
Climate Impacts Group (UW-CIG) has developed annual climate forecasts for regional resource
managers, including annual projections of climate variations due to ENSO and PDO. These
forecasts help inform SPU managers about projected conditions over the winter and spring
months to enable more informed management of the competing objectives of water supply and
flood management (UW-CIG, 2010a).
Observed changes in climate include the following: temperatures increased in the Pacific
Northwest by 1.5°F between 1920 and 2003 (Mote, 2003); annual precipitation increased by 14%
between 1930 and 1995 (Mote, 2003); April 1 snow-water equivalent has declined dramatically
30
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at almost all Pacific Northwest sites (Mote et al., 2003, 2005, 2008; Hamlet et al., 2005); and
timing of peak runoff shifted earlier by 0-20 days between 1948 and 2002 (Stewart et al., 2004).
4.2. DESCRIPTION OF THE WATER SYSTEM
4.2.1. Water Supply System
SPU's water supply comes from three sources: the Cedar River Municipal Watershed, the
South Fork Tolt Watershed, and the Seattle Well Fields (Figure 4; SPU, 2010a).
In 1895, Seattle residents voted to approve revenue bonds to construct the Cedar River
Municipal Watershed. The watershed, almost entirely owned by the City of Seattle, covers
90,638 acres and provides approximately 70% of the city's freshwater supply over the course of
the year. Rain and snowmelt are collected and stored in two reservoirs created by the 1914
construction of the Masonry Dam—Chester Morse Lake and Masonry Pool. As water leaves
these reservoirs, it powers the Cedar Falls hydroelectric power plant. Twelve miles downstream,
at the Landsburg diversion dam, on average, 22% of the river flow is screened to remove debris,
chlorinated for microbial control, and fluoridated for dental health. This water is then stored in
Lake Youngs, where it is ozonated for odor and taste improvements, ultraviolet-disinfected to
disable chlorine-resistant microbes, chlorinated again, and supplemented with lime for
pH-adjusted corrosion control to minimize lead leaching in older plumbing systems.
The Cedar River Municipal Watershed is managed to provide an adequate water supply
(both for human use and instream conservation flows). The water supply system also provides
riverine flood management and hydropower generation. Morse Lake and Masonry Pool hold, on
average, just enough water for one water-cycle year. If too little water is released during winter,
flooding can occur during heavy rains or when the snowpack melts during the spring wet season.
Winter water levels are therefore generally kept low. Conversely, drought conditions in the
spring can prevent the reservoir from refilling to the level necessary to provide water during the
dry summer months. This situation presents a risk tradeoff that SPU water managers must
address every year to meet both riverine flood management and water supply objectives (SPU,
201 Ob).
The South Fork Tolt Watershed is located on the western slope of the Cascade Range,
approximately 35 miles east of Seattle (Figure 4). The City of Seattle purchased water rights to
the South Fork Tolt from the Mountain Water Company in 1936, but no infrastructure existed for
the diversion, conveyance, or distribution of that water. The South Fork Tolt Dam was
-------
Snohomish County
King County
Tolt Pipeline No. 1
South Fork Tolt River
Watershed
South Fork Tolt Dam
Tolt Regulating Basin
and Powerhouse
Tolt Treatment Facility
Seattle
Well Fields
Cedar River __/
Pipeline 1,2.3
Cedar River
Pipeline 4
•Cedar EastsideSupply Line
-Cedar Treatment Facilities
Lake
Youngs
Lake Youngs Supply
Lines Nos. 4 and 5
Landsburg
Diversion
Cedar Falls
Powerhouse
Masonry Dam
Overflow Dike
Chester Morse
Lake
Cedar River Watershed
Kinir.
Cotjniy
Pierce County
Seattle Regional Water Supply System
Seattle City Limits Current Area Served (2006)
^— Transmission Pipeline Seattle Retail Service Area
Water Bodies Seattle Wholesale Customer
Municipal Watersheds
Figure 4. Seattle Public Utilities service area.
Source: SPU (2008).
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constructed in 1963, and in 1964, South Fork Tolt Reservoir began supplying water to north
Seattle and the Eastside. As water leaves this reservoir, it powers the South Fork Tolt
hydroelectric power plant. After a land exchange with Weyerhaeuser Company in 1997, the City
of Seattle owned 69% of the 12,107-acre drainage area upstream of the South Fork Tolt Dam.
Most of the remaining land lies in the Mt. Baker-Snoqualmie National Forest. The South Fork
Tolt Reservoir provides approximately 30% of the city's freshwater supply (SPU, 2008, 2010c).
The reservoir is also operated to manage riverine flooding and maintain instream flows.
SPU's Tolt Treatment Facility, the city's first filtration and ozonation facility, began
operating in 2000. It provides 120 million gallons per day (mgd) of finished water to customers
in Seattle and suburban cities. Although the facility has historically provided very high-quality
water, requiring only minimal treatment, it was designed to allow long-range conformity with
anticipated regulations, to increase system yield, and to permit continuous supply of Tolt water
though periods of high turbidity (SPU, 2010d). Like the Cedar River water supply, the Tolt
supply provides fluoridation, chlorination, and adjustment of pH and alkalinity for corrosion
control (SPU, 2006a).
In 1987, the first groundwater source was added to the system when two wells in the
Highline Well Field began operating. A third well was added in 1990. These wells supply less
than 1% of SPU's water from an aquifer to supplement summer demands when necessary. The
well field can be pumped for 4 months and becomes available in July (WA DOE, 2001).
Water demand for the SPU system peaked in the 1980s at approximately 170 mgd. A
severe drought and mandatory water restrictions in 1992 caused demand to decrease.
Subsequently, higher water rates, plumbing code revisions in 1993, conservation efforts, and
improved systems operations caused demand to level out around 150 mgd. The economic
slowdown in 2000 and continued conservation efforts further reduced demand to approximately
130 mgd. This 24% decrease in demand coincided with a 17% increase in the population of
SPU's service area since 1990 (SPU, 2006a). This equates to a 27% decrease in water
consumption per capita from 145 gallons per day (gpd) per capita to 105 gpd per capita (SPU,
2010e).
4.2.2. Wastewater System
SPU also conveys wastewater to King County's Wastewater Treatment Division,
including associated infrastructure. This drainage infrastructure is partly a combined sewer
system, which means that SPU must address the City of Seattle's stormwater quality and urban
drainage flooding issues, but often in conjunction with King County Department of Natural
Resources and Parks. Because the responsibilities of King County and SPU overlap to some
degree, this case study does not present SPU activities related to drainage and wastewater in
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detail. Of note, however, is that both SPU and King County own conveyance infrastructure
within the city, and that combined sewer overflow events are a problem for both entities. SPU
has explored the implications of climate change on its stormwater infrastructure and operations.
SPU also is pursuing and evaluating adaptation options, engaging in research, and participating
in collaborative networks to address stormwater issues—effectively replicating their experience
with water supply, but for drainage and wastewater issues.
4.3. CLIMATE CHANGE PROJECTIONS AND RISKS
SPU expects climate in the Seattle area to change in several ways. Global climate models
(GCMs) project that temperatures will warm at a rate of 0.5°F per decade, nearly three times the
rate experienced over the twentieth century. Most models suggest small changes in annual
precipitation compared with year-to-year and decade-to-decade variability observed for the
twentieth century. Most models, however, do indicate increased winter precipitation and
decreased summer precipitation. The potential future impacts of these changes include
decreased mountain snowpack, higher winter and lower spring streamflows, increased
sea-surface temperatures, rising sea levels, and increased winter riverine flooding (UW-CIG,
201 Ob; City of Seattle, 2006). Table 3 provides a summary of projected temperature and
precipitation changes in the Pacific Northwest from the Washington State Climate Change
Impacts Assessment. Projected changes are based on simulations from 20 climate models and
two greenhouse gas emissions scenarios (Bl and A1B; UW-CIG, 201 Ob).
A series of severe droughts in 1987, 1992, and 1997-1998 increased the sensitivity of
SPU managers to the effects of climate on their water supply. A very dry summer in 1987
caused significant declines in raw-water supply quality and forced use curtailments, reduced
instream flows for fish, and necessitated the installation of an emergency pumping station to
access low water in Chester Morse Lake. In response, the City developed a Water Shortage
Contingency Plan (updated in SPU, 2006b) and a state-of-the-art reservoir management and
streamflow forecasting model for use in real-time water management and long-range planning.
The 1992 water shortage was caused by following standard flood control rules after a
below-normal winter snowpack. When the spring season also produced below-normal
precipitation, SPU's mountain reservoir levels did not recover, and mandatory water restrictions
were in place by mid-May. Throughout the summer, raw-water quality declined, leading to a
decision to invest in an ozone-purification plant. SPU also implemented dynamic flood-control
rules, which, in conjunction with enhanced real-time snow, weather, and streamflow monitoring
networks, allowed SPU to implement its new reservoir management approach. Finally, in 1997,
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Table 3. Projections of changes in annual mean temperature and
precipitation for the 2020s, 2040s, and 2080s
Time period
Temperature
°F("C)
Precipitation
%
2020s
Low
Average
High
+1.1 (0.6)
+2.0(1.1)
+3.3 (1.8)
-9
+1
+12
2040s
Low
Average
High
+1.5 (0.8)
+3.2 (1.8)
+5.2 (2.9)
-11
+2
+12
2080s
Low
Average
High
+2.8 (1.6)
+5.3 (3.0)
+9.7 (5.4)
-10
+4
+20
new research on ENSO effects on the Pacific Northwest was incorporated into SPU's reservoir
management decisions. In anticipation of lower-than-normal snowpack followed by a hot, dry
summer, SPU allowed its mountain reservoirs to fill higher than normal and reduced its
operational use of water. These proactive decisions allowed the 1997-1998 drought to pass
without the public's experiencing any water shortage or restrictions (UW-CIG, 2010c). Another
record low snowpack in 2005 threatened water shortages and use restrictions, but, again, careful
water management and late spring rains allowed SPU to meet all water supply and instream flow
requirements without restrictions.
SPU's predecessor agencies were engaged with the issue of climate change as far back as
the 1980s when they helped to develop the American Society of Civil Engineers' policy on
global climate change. Informal tracking of climate variability and change issues by SPU staff
followed, leading to SPU's formal integration of ENSO into its 1997-1998 reservoir
management decisions. In 2002, SPU contracted with UW-CIG to study the potential impacts of
climate change and to develop methods for how SPU could incorporate future climate change
into its water supply planning (SPU, 2006a). The impacts on water supply projected in the study
were reported and incorporated into SPU's 2007 Water System Plan. In a subsequent project,
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SPU began a new collaboration with UW-CIG to investigate climate change in partnership with
the Cascade Water Alliance, Washington State Department of Ecology, and King County
Department of Natural Resources and Parks as described below (RWSP, 2010).
Participating agencies formed a Climate Change Technical Committee in spring 2006.
The committee included SPU, along with a number of other city, county, state, and tribal
government officials managing water resources in the region. The committee met 17 times from
March 2006 through December 2007, and drafted a charter in April 2006 containing the
following goals:
• Identify the basic building blocks of our understanding of climate change
• Identify what is known about climate change in the Puget Sound region and its potential
impacts
• Identify where more information would be useful
• Communicate what is known to other committees in this process
• Document the committee's findings (Palmer, 2007).
The committee reviewed 10 technical reports written by a University of Washington
research team before the reports were publicly released. SPU used information from this work to
assess impacts to water supply and demand as described in Section 4.4.
SPU also joined several other major utilities to form the Water Utility Climate Alliance
(WUCA) in early 2007. WUCA commissioned two climate change white papers; one of which
SPU managed. The first white paper outlines potential improvements to scientific models for
projecting the impacts of climate change at spatial and temporal scales relevant to utilities
(Barsugli et al., 2009). The second white paper outlines decision-making approaches to address
climate change in water resource planning and management in the face of uncertainty about
future climate conditions (Means et al., 2010). In addition to WUCA, SPU is involved in several
other collaborative efforts to enhance the capacity of the water sector to identify and prepare for
the impacts of climate change. A staff member from SPU co-chaired the U.S. Environmental
Protection Agency's (U.S. EPA's) Climate Ready Water Utilities Working Group, which is
developing recommendations on how the U.S. EPA can support a "climate-ready" water sector.
SPU is a member of the Water Research Foundation's Climate Change Strategic Initiative Expert
Panel, which is assisting the Foundation in developing a multiyear climate change research
agenda for the drinking-water sector. This effort is part of a similar one led by the Water
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Environment Research Foundation to develop climate research for the clean-water sector.
Finally, SPU is collaborating in a new project initiated in 2010 called Pilot Utilities Modeling
Applications (PUMA). PUMA includes five utilities and four National Oceanic and
Atmospheric Administration-funded Regional Integrated Sciences and Assessment (RISA)
groups that will be collaborating on downscaling climate models and using them to assess
climate change effects on water supply.
SPU operates in a political and managerial environment that supports engagement on
climate change adaptation. The City of Seattle took early leadership roles in climate change on
both the mitigation and adaptation front. On February 16, 2005, for example, Seattle Mayor
Greg Nickels launched the U.S. Conference of Mayors Climate Protection Agreement. Mayor
Nickels made climate protection a keystone issue of his administration, creating the City of
Seattle's Environmental Action Agenda in 2005, including the Seattle Climate Protection
Initiative and the Seattle Climate Action Plan. The need to adapt to changes in water supply was
highlighted in the Seattle Climate Action Plan (City of Seattle, 2006). According to this plan, "It
is vital that the City—and all levels of government—plan and prepare for the climate change that
is inevitable. Because Seattle's water and hydroelectricity are so dependent on the hydrology
cycle in the Cascade Mountains, the City has focused its planning and adaptation analysis work
there." By the time this was written in 2006, SPU had already begun looking at climate change
in earnest.
4.4. VULNERABILITY ASSESSMENT
SPU has commissioned or conducted a series of increasingly sophisticated analyses over
the course of many years to examine the vulnerability of their water supply and stormwater
infrastructure and operations to climate change. The analyses have benefitted from the expertise
of UW climate scientists and others associated with the NOAA RISA program's Climate Impacts
Group (UW-CIG). Over the course of nearly a decade, SPU and their collaborators refined a
model-driven vulnerability analysis that projects changes in global climate, downscaled those
changes to Seattle and its watersheds, and ran those projected changes through SPU's system
models to determine how climate change might affect SPU's water supply, water infrastructure,
and operations. The SPU study methodology represents a scenario-based approach to
vulnerability assessment. For more detailed information on how SPU and other utilities
organized their vulnerability assessments, see the companion report, Climate Change
Vulnerability Assessments: A Review of Water Utility Practices (U.S. EPA, 2010).
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4.4.1. Water Supply
Downscaled scenarios of future temperature and precipitation change were developed for
the Puget Sound region using three combinations of climate model/greenhouse gas emissions
(from the IPCC Special Report on Emissions Scenarios; SRES) and four time periods (IPCC,
2000). The three climate model/SRES combinations include a "middle-of-the-road" regional
climate change scenario (MPIECHAM5/A2) with moderate warming and precipitation increase,
a significantly wetter and warmer scenario (TPSL-CM4/A2), and a slightly drier and warmer
scenario (GISS-ER/B1).9 The four time periods were a 2000 hindcast and projected future
conditions for 2025, 2050, and 2075. Climate models were selected because they performed
well in other studies replicating temperature and precipitation trends of the Pacific Northwest
during the twentieth century (Mote et al., 2005). A statistical downscaling approach was used to
translate GCM grid-scale output to a quasi-steady-state daily time series of temperature or
precipitation for a specific location at a specific future time that preserves the historic variability
of climate (Polebitski et al., 2007a; Polebitski et al., 2007b).
SPU's water supply planning model is the Conjunctive Use Evaluation (CUE) systems
model—a weekly time-step simulation model of the Cedar and Tolt River systems. Because it
uses observed inflow data for both river systems as input, however, CUE cannot directly
incorporate climate model output (temperature and precipitation). Consequently, UW-CIG ran
the downscaled meteorological data sets through its Distributed Hydrology Soils and Vegetation
Model (DHSVM) to produce climate-altered hydrologic data sets for use in CUE. CUE is used
for calculating the firm yield10 and reliability of Seattle's water supply system and potential
future water supply projects. CUE results indicated that yield decreased under all climate change
scenarios for all time periods. SPU also ran several planning scenarios through CUE to
determine whether available supply could be increased to compensate for anticipated supply
shortfalls.
4.4.2. Water Demand
SPU examined the effect of climate change on water demand using a dual approach of
regression analysis and forecast modeling. First, SPU performed a regression analysis of
peak-season consumption for 1982-2007 using monthly consumption data, maximum
temperature, and rainfall at SeaTac Airport for May through September. This relationship was
assumed to hold in the future. SPU had also already developed a demand forecasting model for
9Note that the A2 emission scenario is relatively high by the second half of the twenty-first century, while the
Bl scenario has the lowest level of greenhouse gas emissions of the SRES family.
10Firm yield is a calculation of how much water can be guaranteed from a water system, in this case, based on a
98% reliability standard.
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its 2007 Water System Plan and used this model to forecast non-climate-related changes in
demand (SPU, 2006a). In this study, demand was forecast to decrease below historic levels
through 2050, but to increase above historic levels by 2075. Applying the results of the
regression analysis to these forecasts adjusts demand slightly upward due to the climate change
scenarios in 2025 and 2050. In 2075, a larger climate-induced increase in conjunction with
significant increases in baseline demand led to 2075 demands increasing to above historic levels.
4.4.3. Storms and Runoff
SPU also engaged a consultant to use the University of Washington's Weather Research
and Forecasting (WRF) regional climate model to examine projected precipitation changes in the
Thornton Creek Watershed (Northwest Hydraulic Consultants, 2009). This study was focused
on storms and runoff, and is distinct from the statistical downscaling study of water supply
described previously. Northwest Hydraulic Consultants used the WRF model to dynamically
downscale temperature and precipitation data from two GCM-scale simulations (CCSM3 model
with A2 SRES, and ECHAM5 model with the A1B SRES ) for two 31-year periods (1970-2000
and 2020-2050) to grid sizes of 20 and 36 km2. These data were used in the rainfall/runoff
model Hydrologic Simulation Program-Fortran (HSPF) to model changes in several creek
parameters for the entire Thornton Creek Watershed. The results of the study indicated that
runoff would increase, except at one sub-basin where modeling results diverged, although the
magnitude of the increases varied by a factor of two at times. This work, however, was deemed
too uncertain for SPU's planning purposes. According to the study's conclusions, "Additional
work is needed to improve confidence in future projections before applying dynamically
downscaled data to stormwater planning, policy, or design standards" (Northwest Hydraulic
Consultants, 2009). SPU currently is not using modeled climate projections for stormwater
planning purposes.
4.5. APPLICATION OF VULNERABILITY ASSESSMENT INFORMATION
SPU arguably has undertaken the most sophisticated vulnerability assessment of any of
the utilities discussed in this report, and is the only one of the four utilities that directly used the
results to make an adaptation decision. SPU has also identified a more far-reaching set of
adaptation options for use in future decades in the event that demand exceeds available water
supplies. Prior to this analysis, SPU was already considering how to make the most effective use
of usable storage, including the use of dynamic rule curves that use current watershed state
conditions instead of relying on past hydrologic records. SPU also had a conservation program
that had led to significant reductions in demand since the mid-1980s and more recently, has
committed to an additional 15 mgd of conservation by 2030. This analysis demonstrated what
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SPU already knew, that demand could exceed supplies in 2075 even without climate change,
with no new conservation programs past 2030.
4.5.1. Water Supply
Based on the information generated by its water supply vulnerability assessments, SPU
determined that available water supply decreased under all scenarios for all time periods.
Projections for 2025 indicated Seattle's water supply would decrease by 6-10%, projections for
2050 indicated a decrease of 6-21%, and projections for 2075 indicated a decrease of 13-25%.
Demand was projected to decrease in 2025 and 2050 to around 83% of historic supply but
increase in 2075 to approximately 106% of historic supply.
Based on these projections, SPU analyzed "Tier 1" low- or no-cost intrasystem
modifications that effectively increased the usable storage capacity for water with no new supply
infrastructure.11 This approach primarily consisted of eliminating conservative operating
assumptions from SPU's water system supply calculations.12 These low-cost modifications were
estimated to compensate for supply shortfalls in all three scenarios in 2025, in two of three
scenarios in 2050, and in none of the three scenarios in 2075.
"Tier 2" alternatives were identified that could compensate for the remaining projected
shortfalls in 2050 and 2075. These included additional use of Lake Youngs storage,
modified/optimized conjunctive use operations, and additional conservation programs after 2030.
Even more expensive or complex alternatives were identified for "Tier 3," "Tier 4," and "Tier 5"
spanning from reservoir operational changes to new supply alternatives, but these higher cost
modifications were deemed unnecessary through 2075.
All of these policy options were directly informed by the quantitative results of the SPU
vulnerability analysis. SPU has decided that its vulnerability analysis indicates no need for
near-term operational changes or new infrastructure. In one sense, SPU has not changed its
water supply planning and management decisions because, although significant, the projected
climate impacts are not imminent. On the other hand, the changes to conservative operating
assumptions represent an important class of "no-regrets" adaptations. Even the Tier 2
adaptations, such as increased water conservation efforts, represent policy options that provide
benefits in terms of supply reliability, regardless of the magnitude of climate change. In SPU's
current estimation, no adaptations beyond Tier 2 will be needed through 2075.
nTier 1 did include one structural adjustment—the raising of one overflow dike.
12Changes include, among others (1) allowing Chester Morse Lake to refill to 1,563 ft (versus 1,560 ft), increasing
Cedar River watershed storage by 12%; and (2) allowing South Fork Tolt Reservoir drawdown to 1,690 ft (versus
1,710 ft), increasing Tolt watershed storage by 18%.
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4.5.2. Storms and Runoff
The results of SPU's dynamical downscaling and urban drainage study provided
insufficient certainty to be useful for planning purposes. Consequently, SPU is relying on a
qualitative understanding that intense precipitation events are likely to increase and is exploring
changes in peak storm events as a proxy for changes in precipitation due to climate change. This
approach represents an important hedging strategy. In the absence of reliable projections of
future climate conditions, SPU decided to apply a safety factor to new infrastructure construction
to ensure that new investments would perform their intended function over their useful lives
based on a general understanding of the climate trends and a reasonable estimate of the
magnitude of that change.
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5. SPARTANBURG WATER
Spartanburg Water is a public water and wastewater utility that is composed of
two distinct legal entities: Spartanburg Water System (SWS) and Spartanburg Sanitary Sewer
District (SSSD). The two entities function as one company (West, 2010). SSSD was formed as
a special-purpose district for wastewater services. SWS is a political subdivision of the City of
Spartanburg and is overseen by three Commissioners of Public Works. SSSD is overseen by the
seven-member Sewer Commission, which includes the three Commissioners of Public Works
(Spartanburg Water, 2010a; West, 2010).
5.1. BACKGROUND
Spartanburg Water serves a population of approximately 180,000 people in Spartanburg
County and portions of Greenville, Cherokee, and Union Counties in South Carolina
(Spartanburg Water, 2010a). The SWS service area includes a contiguous retail service area of
9 9
approximately 259 mi , a noncontiguous retail service area of approximately 15 mi , and a
wholesale service area of approximately 605 mi2(Spartanburg Water, 2010a). The SSSD
wastewater service area is defined by the Spartanburg city limits—a contiguous service area
covering approximately 196 mi2, and a noncontiguous service area of eight locations serving
approximately 22 mi2 (Spartanburg Water, 2010a).
From 1971 to 2000, Spartanburg County received on average 61 inches of rain per year
(SRCC, 2010). Precipitation is somewhat consistent throughout the year, ranging on average
from 3.44 to 6.86 inches per month (SRCC, 2010). The average minimum and maximum
temperatures are 48.6°F and 71.3°F, respectively (SRCC, 2010). Over the past 10 years,
however, the southeastern region of the United States has experienced prolonged droughts that
have lasted several years. The Spartanburg Water service area experienced droughts in 2002 and
2003, and a drought has persisted since 2005, with the lowest recorded streamflow occurring in
2009 (West, 2010).
5.2. DESCRIPTION OF THE WATER SYSTEM
5.2.1. Water Supply System
Spartanburg Water provides approximately 30 million gallons of water to its customers
each day. Approximately 60% of the water use is residential (West, 2010). Industrial water use
has significantly declined in the past decade from 110 to 52 industrial accounts (West, 2010).
Although there are commercial and other small business accounts, these sectors are not
significant water users.
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Three reservoirs on the Pacolet River provide the vast majority of the Spartanburg water
supply (Figure 5). Bowen Reservoir, the most northern reservoir, is on the south fork of the
Pacolet River. Built in 1960, it covers 1,534 acres and has a total capacity of 17,115 acre-feet
(Spartanburg Water, 201 Ob; West, 2010). Water from Bowen Reservoir flows downstream to
Municipal Reservoir Number 1 (MR1), which is located just above the confluence of the North
and South Pacolet Rivers. Built in 1926, MR1 serves mainly as a pass-through reservoir with a
capacity to store approximately 1 day's worth of water. MR1 improves water quality through
sedimentation as the water flows through it (West, 2010). Blalock Reservoir is downstream from
the confluence of the North and South Pacolet Rivers and receives inflow from MR1 and the
North Pacolet River. Built in 1983, Blalock Reservoir covers 1,105 acres and has a total
capacity of 16,894 acre-feet (Spartanburg Water, 201 Ob; West, 2010). Spartanburg Water
expanded Blalock Reservoir in 2006 by raising the height of dam to meet projected future water
demand (Spartanburg Water, 2009).
SPARTANBURG WATER SVi
RESERVOIR WATERSHE
Figure 5. Reservoirs and watersheds of the Spartanburg water system.
Source: Spartanburg Water (2009).
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Two smaller water sources supplement the reservoir system: Vaughn Creek and an
unnamed stream off Hogback Mountain provide approximately 800,000-900,000 gallons per day
(gpd) of water. These sources supply the Landrum Water Treatment Plant (WTP), which has a
capacity of 1 million gallons per day (mgd). Landrum WTP also has a groundwater backup
source with a pumping capacity of 50,000 gpd (West, 2010).
In addition to Landrum WTP, two other plants provide drinking water treatment.
R.B. Simms WTP, located at Bowen Reservoir, has a capacity of 64 mgd, and Blalock WTP,
located at Blalock Reservoir, has a capacity of 22.5 mgd. Spartanburg's three water treatment
plants provide full conventional treatment, including sedimentation, filtration, and chlorination
(West, 2010).
The distribution system is composed of 1,308 miles of pipes (West, 2010).
Hydroelectricity produced at R.B. Simms WTP is used to support the water treatment operations.
Hydroelectricity is not generated, however, when Spartanburg Water operates in full
conservation mode during droughts. Operating in conservation mode can have a significant
effect on the utility's energy costs, especially during peak hours, because peak usage can set the
pricing for the month for all of its electricity use (West, 2010).
Discharges from Blalock Reservoir are managed to meet instream flow requirements
based on a combination of factors, including the water level in Blalock Reservoir, the time of
year, and flow into the reservoir system. Because of spawning offish downstream, the South
Carolina Department of Health and Environmental Control (SC DHEC) issued Spartanburg
Water a permit that set the downstream flow requirements and determined the 7Q10 for Pacolet
River13. In the event of a persistent drought, Spartanburg Water may request permission for
reduced releases, provided it conducts additional monitoring to ensure fish health and water
quality (West, 2010).
5.2.2. Wastewater System
Spartanburg Water has 10 wastewater treatment plants (WWTPs) that range in capacity
from 50,000 gpd to 25 mgd. The largest of the 10 plants, Fairforest WWTP, is located just
downstream of Blalock Reservoir. All 10 WWTPs provide secondary treatment. Discharge
permits for the WWTPs are calculated based on the 7Q10, which is determined in part by
releases from the reservoirs; therefore, there is a relationship between Spartanburg Water's
ability to withdraw water and discharge wastewater. In total, approximately 13 mgd of
wastewater is collected, treated, and discharged into the Pacolet River (West, 2010).
13The 7Q10 is the lowest streamflow for 7 consecutive days that is expected to occur once every 10 years.
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Spartanburg Water owns, operates, and maintains 940 miles of wastewater collection
pipes throughout the service area (West, 2010). Some infiltration and inflow occur during storm
events. A separate storm sewer system is maintained by the city and county and does not fall
under Spartanburg Water's jurisdiction (West, 2010).
5.3. CLIMATE CHANGE PROJECTIONS AND RISKS
Spartanburg Water is aware that projected climate change could affect its water and
wastewater systems. The utility expects droughts in the region to increase in frequency and
severity with greater variability in precipitation. Spartanburg Water also expects severe storm
events, such as hurricanes and tropical storms, to increase in frequency and severity.
Spartanburg Water identified these projected climate changes and their potential effects
on its water and wastewater systems and operations in a variety of ways. One staff member
attends meetings of the South Carolina State Drought Response Committee, whose chair is the
State Climatologist and where projected climate change for the area is often discussed
(Spartanburg Water, 2010c). Networking within the water utility community has provided
information on approaches other utilities are using to examine and address climate change. For
example, Spartanburg Water's Deputy General Manager of Engineering and Technical Services
served as the President of Water Environment Federation. This provided her the opportunity to
visit other domestic water utilities, including those in Las Vegas, East Bay in California, and
Seattle, in addition to water utilities in Europe, South Africa, and Tanzania. Also, she and other
Spartanburg Water staff often attend conferences to follow the activities of and consult with
other utilities (West, 2010).
Mainly because of the prolonged and repeated droughts in recent years, Spartanburg
Water is considering the effects of climate change on its infrastructure and operations. The
droughts of the past decade have exacerbated many of the existing vulnerabilities of the
Spartanburg Water system, including increased water demand from population growth, changes
in land use patterns affecting water quantity and quality, and increasing frequency of droughts
and extreme storm events affecting quality and flooding (West, 2010).
Most of the expected effects of climate change will require increased management of
existing vulnerabilities, rather than addressing completely new challenges (West, 2010). For
example, one of Spartanburg's water conservation efforts for drought management is a pricing
structure with increasing block rates, which discourages water use beyond a certain minimum
level and generally serves to discourage outdoor water use. With potential for more frequent or
more severe droughts with climate change, Spartanburg Water might implement this pricing
structure along with other enhanced drought management approaches to conserve additional
water.
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5.4. CLIMATE CHANGE VULNERABILITY ASSESSMENTS
Spartanburg Water assessed their potential vulnerability to climate change using existing
information on climate change projections, experience from recent extreme events in their
region, and experiences of other utilities. Based on this assessment, Spartanburg Water believes
the effects of climate change will exacerbate existing vulnerabilities. As a result, rather than
undertaking completely new activities or management approaches, the utility is incorporating
climate change into many of its existing management activities. Climate change is now a
consideration in all utility planning processes and incorporating climate change is part of the
utility's culture (West, 2010). To better consider climate change in its decisions, Spartanburg
Water attempts to stay current on regional climate change projection data. It also collects and
tracks a variety of data relevant to climate change, including rainfall, temperature, streamflow,
reservoir levels, groundwater levels, water usage, revenue streams, public perception, and Web
sites (West, 2010).
Spartanburg Water's consideration of climate change takes into account the potential
effects of climate change throughout its entire system—from providing sufficient water supplies
to ensuring an uninterrupted supply chain for treatment chemicals during extreme weather events
(West, 2010). This holistic approach to the system and operations—the result of Spartanburg
Water's past experiences (such as having an interrupted supply of treatment chemicals following
Hurricane Katrina) or lessons learned from other utilities—is essential because many aspects of
the system are interconnected. For example, the release of water from Blalock Reservoir for the
water system affects the 7Q10 determination for wastewater discharge permitting. Another
example of Spartanburg's system-wide thinking is its understanding of the potential effect of
water conservation programs on its revenue.
Spartanburg Water has a reservoir management model to support its management and
water use decisions throughout the supply system. It also is currently developing a hydraulic
model for the wastewater system. Combined with information on projected climate change,
Spartanburg Water believes these models of their existing systems will enable them to assess the
potential consequences of climate change on the system and allow the utility to consider
adaptation actions accordingly.
5.4.1. Water Quantity
One of the primary considerations for the water supply system is sufficient water
quantity. In the past 10 years, population growth has increased water demand in the Spartanburg
Water service area and in six other water districts in the county downstream of Spartanburg
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Water. Additionally, continued development has led to more impervious surfaces, which in
some cases have redirected runoff outside of the reservoirs' watersheds, thereby reducing supply.
The recent prolonged drought experienced in the region has affected not only surface
water but groundwater resources as well. Although the main water source for the Spartanburg
Water system is surface water, groundwater contributes to baseflow and, therefore, surface water
supplies. Multiple and prolonged years of drought impact groundwater supplies, which can take
several years to recover. This results in a continued risk to surface water supply sources beyond
the length of the drought (West, 2010). Also, during these drought periods, people living within
Spartanburg County who obtain their drinking water from groundwater sources and are not
serviced by Spartanburg Water request to be added as a customer because groundwater sources
are insufficient. Often these requests originate from areas where water distribution systems do
not already exist. This issue can be a challenging to manage because often public expectations
are for the utility to provide access to water (West, 2010).
Change in water quantity can also affect wastewater system operations. Several of
Spartanburg Water's WWTPs discharge to small streams, where wastewater discharges can
constitute up to 80% of streamflow (West, 2010). With prolonged drought, Spartanburg Water
anticipates that the future permit limits for these facilities will change if the 7Q10 changes for the
receiving streams. In an adjacent county, similar conditions resulted in the wastewater utility
upgrading to tertiary treatment. Some of the 7Q10 determinations are expected to undergo
review in 2012. The result of these reviews could require additional capital planning and
"creative treatment strategies in the interim" (West, 2010).
5.4.2. Water Quality
In addition to drought conditions, the Spartanburg Water service area has experienced
extreme rain events, including tropical storms and hurricanes. These events caused flooding
throughout the area and damaged components of Spartanburg Water's facilities (West, 2010).
With the increased frequency and severity of such storms projected to happen because of climate
change, preventive and restorative efforts will require additional planning and financing.
Additionally, when combined with continued land development, water quality problems resulting
from impervious surface runoff will be exacerbated. Impervious surfaces are a significant water
quality concern because runoff of sediments, contaminants, oil, and grease is increased. Because
Spartanburg County has no zoning laws, land use changes (and accompanying development and
impervious surface increases) can be unpredictable in some areas (West, 2010).
Extreme storm events and droughts, especially in combination, have been associated with
taste and odor problems in Bowen Reservoir and MR1. The problems are caused by high levels
of geosim, which is a naturally occurring compound produced by certain soil bacteria and
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blue-green algae, depending on environmental conditions, including water temperatures, nutrient
enrichment, and turbidity (USGS, 2009). SC DHEC determined that both reservoirs were fully
supportive of all uses based on established criteria. An investigation by Spartanburg Water and
the U.S. Geological Survey found that nutrient enrichment was not the contributing cause of the
elevated geosim levels but that streamflow and the resulting hydraulics within the reservoir
system affect the production and release of geosim by blue-green algae (West, 2010).
Hydraulics affects sedimentation or re-suspension of sediment, which, in turn, affects the
penetration of sunlight and the temperature of the water—both factors in the release of geosim.
Today, Spartanburg Water has a monitoring system in place that helps predict when geosim
events might occur.
The two main weather events that can trigger geosim release are (1) droughts, when
water clarity is greatly increased by lower reservoir levels and slower streamflow; and (2) major
storm events, when hydraulic surges stir up sediment in the system, releasing phosphorus and
resulting in an increased abundance of blue-green algae. The highest levels of geosim were
observed in 2003-2005 when tropical storms followed droughts in 2002 and 2003(West, 2010).
Because these two main contributing factors are both predicted to increase in severity and
frequency, Spartanburg Water expects that climate change will exacerbate the geosim water
quality problem and could require additional management.
5.4.3. Infiltration/Inflow
With projected increases in the intensity of storm events, Spartanburg expects infiltration
and inflow into the wastewater collection system to increase. Increased infiltration and inflow
could threaten the capacity of the system to handle wastewater flow during these events.
5.5. APPLICATION OF VULNERABILITY ASSESSMENT INFORMATION
Spartanburg Water does not expect climate change to introduce new challenges but rather
to exacerbate existing vulnerabilities. Given both its climate experiences of the past 10 years in
the form of increased frequency and duration of drought and its information about projected
climate change, Spartanburg Water has initiated a utility-wide effort to incorporate climate
change into its planning processes. Spartanburg Water has combined its environmental,
operational, and financial data with its understanding of the water system to qualitatively assess
the potential effects of projected climate change on its infrastructure, operations, and customer
needs. It has also changed its planning and management, particularly by increasing the
flexibility of its system and operations.
As part of long-term water supply planning, in 2006, Spartanburg Water doubled the
capacity of Blalock Reservoir, based on a study conducted in the 1990s. When this project was
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completed, Spartanburg Water rethought its management strategy for the reservoir system as a
result of extended droughts in the Southeast. Based on a set of indicators, including streamflow
and long-term weather forecasts, reservoir releases are managed for maximum water storage
when signs of prolonged drought are present and hydroelectric power generation might be
suspended14. Also, because Bowen and Blalock Reservoirs support recreational activities and
adjoining properties are permitted to directly withdraw water from the reservoirs for lawn
irrigation, recreational activities were limited, and water conservation requirements were
instituted. Spartanburg Water asserted its right to discontinue all withdrawals for lawn irrigation
from the reservoirs during droughts (West, 2010).
Spartanburg Water also revised its Water Demand Management Plans and became a
WaterSense® Partner and Charter Sponsor of The Alliance for Water Efficiency. Aggressive
water conservation campaigns were launched throughout the community, including placing
educational kiosks and rotating them through public areas. Spartanburg Water promotes water
conservation year round, regardless of drought conditions.
As a result of the conservation program and decreased industrial water use, Spartanburg
Water has realized a reduction of 10 mgd in water use, and the summer peak demand has been
reduced by 5 mgd. Because of this decreased demand, the time that water resides in the
distribution system has increased, so Spartanburg Water is considering taking some ground
storage offline or retrofitting lines to minimize this time or both. These lines and storage
options, however, will be maintained in place for future use. This plan could prove useful, with
potential increases in water demand from new customers or increased demand with climate
change. In the next 4 years, Spartanburg Water plans to spend $3 million on its water
distribution system (Spartanburg Water, 2010d).
The combination of Spartanburg Water's water conservation program and loss of many
industrial accounts has resulted in a sustained loss of approximately 13% of the utility's typical
revenues in the past 2 years. Spartanburg Water is now re-evaluating its revenue streams and
management strategies to ensure not only environmental but also financial sustainability (West,
2010).
On the wastewater side of the system, Spartanburg Water has plans to evaluate the
feasibility of modifying future treatment at 3 of the 10 WWTPs (Spartanburg Water, 2010e).
The three benefits cited for the projects include the assurance of the effectiveness of ultraviolet
light disinfection at these plants, potential future reuse of water, and continued compliance with
discharge permits by providing "additional treatment that may be needed with fluctuations in
stream flows from climate impacts" (Spartanburg Water, 2010e).
14 Hydroelectric power is used to pump water into the distribution or storage system.
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To address the potential increase in infiltration and inflow into the wastewater collection
system, Spartanburg Water adopted a new strategy when upgrading pipes in the wastewater
collection system. Instead of closing off the old pipes, they were left in place to provide
additional capacity during storm events and additional flexibility in managing the projected
effects of climate change.
Spartanburg Water has been able to gather information on climate change impacts and
adaptation by attending state-level drought committee meetings and networking with other water
utilities. It does not, however, have the benefit of a state-level water program that assesses
available water resources or provides guidance on projected climate change. Not having a
state-level water program limits Spartanburg Water's long-term planning and modeling.
Spartanburg Water notes that the most helpful resources for continuing to address climate change
would be the availability of more environmental data, descriptions of best practices and
management tools, and case studies of other utilities' actions. Addressing overlapping
regulations and coordinating regulations on a watershed basis among surface water,
groundwater, wastewater, stormwater, and other water resource-related programs also would
facilitate Spartanburg Water's efforts to manage its water resources efficiently and sustainably in
the face of continued climate change (West, 2010).
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6. SUMMARY
Each utility featured in this report is faced with a unique set of issues and challenges
related to climate change. Although the issues and challenges vary, several summary
observations can be made that might be useful to other utilities and members of the water
resources community regarding the conduct and use of climate change vulnerability assessments
to support adaptation.
• Conducting climate change vulnerability assessments appears to have increased
awareness of climate change risks, informed decision making, and supported adaptation
at the utilities featured in this report. One theme emerging from the case studies is the
need to consider climate change in a holistic context, taking into account all factors
affecting system performance.
• Utilities have worked with climate scientists and modelers to obtain data and gain insight
into how climate science can be used to inform their decision making. SPU collaborated
with the UW-CIG, DEP collaborated with Columbia University and the City University
of New York, and EBMUD used an analysis conducted by the State of California and the
California Climate Change Center. In contrast, Spartanburg relied on information
gathered from briefings and staff contact with other utilities through participation in the
Water Environment Federation and the American Water Works Association but did not
formally collaborate with the climate change research community to develop
region-specific data on their climate change risks.
• Uncertainties in vulnerability assessments or climate science need not delay adaptation
action. All four utilities described in this report have taken action to reduce their climate
risk despite significant, remaining uncertainties regarding the potential impacts of climate
change. Often, these actions also address other concerns, such as managing limited
supplies using water conservation or water reuse. Nonetheless, climate change
vulnerability analyses can help inform and prioritize among management decisions.
• The large utilities used a wide array of climate change scenarios to capture some of the
uncertainty about future climate change. EBMUD conducted a "bottom-up" approach by
performing sensitivity analyses to improve its understanding about how climate change
could affect particular elements of its water resource system. SPU and DEP conducted
what are often referred to as "top-down" approaches driven by climate change scenarios
and models.15
• Vulnerability analyses to date have focused mainly on water supply and demand. All
four utilities focused their climate change impacts and vulnerability work principally on
water supply and demand. Although the utilities expressed concern about the effects of
15 For more on the difference between "top-down" and "bottom-up" approaches, see Miller and Yates (2006), Freas
et al. (2008), and Stratus Consulting and MWH Global (2009).
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climate change on water quality, urban drainage, wastewater, and other aspects of their
systems, these areas have not yet received the same level of attention as water supply.
• The utilities used system-specific models to understand and manage potential climate
impacts on their systems. All case studies except Spartanburg Water used their system
hydrology, operations, or planning models to evaluate the effects of potential climate
change on their systems. The models were used to assess whether operational changes
would be sufficient to cope with the effects of climate change, or whether system
changes, such as adding supplies or further reducing demand, also were necessary. These
models did not always align with the output of climate models, necessitating tailored use
of climate projections for each utility. Spartanburg Water used existing system models to
understand their system's behavior and qualitatively determine expected climate change
impacts.
• The case studies demonstrate that a variety of methods can be used to understand
vulnerability and analyze adaptation options. Scenario analyses, sensitivity analyses,
state-of-the-science literature reviews, and peer information sharing were used in
different combinations in the four case studies to understand the potential impacts of
climate change. The sensitivity analysis EBMUD performed on their existing system
model and the literature review and information gathering from peers Spartanburg Water
performed demonstrate two paths that utilities lacking the financial and staff resources to
support detailed modeling studies can take to assess their vulnerability to climate change.
• Utilities expressed an interest in having their needs reflected in future research. Utilities
specifically requested higher resolution climate change projections at the spatial and
temporal scales at which they operate, probabilities associated with projected changes,
and guidance on appropriate climate change parameters and scenarios to consider and
plan for in their regions. One recommendation was to establish a central repository of
data to support climate change and adaptation analysis.
• The results of vulnerability assessments by the four utilities were used in different ways to
inform and support adaptation. SPU responded directly to the results of the vulnerability
analysis by evaluating the impact of conservative operational assumptions on reservoir
management. The other utilities used their vulnerability assessments to increase
knowledge about their climate change risks, integrate information on these risks into
decision making, and provide support for adaptation measures.
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REFERENCES
AWWA (American Water Works Association). (1997) Climate change and water resources. Committee report of the
AWWA public advisory forum. J Am Water Works Assoc 89(11): 107-110.
Barsugli, J; Anderson, C; Smith, JB; et al. (2009) Options for improving climate modeling to assist water utility
planning for climate change. Prepared for Water Utility Climate Alliance. December. Available online at
http://www.wucaonline.org/assets/pdf/actions whitepaper 120909.pdf.
Brunette, V; Germain, R. (2003) Forest management in the New York City watershed. World Forestry Conference,
Quebec City. Available online at http://www.fao.org/docrep/article/wfc/xii/0649-b3.htm.
Chan, C. (2010) Personal communication on April 2, 2010, between Clifford Chan, Manager of Water Treatment
and Distribution, EBMUD, and Viktoria Zoltay, Abt Associates.
Cheng, S. (2010) Personal communication on April 5 and 7, 2010, between Stephanie Cheng, Associate Engineer in
Resource Recovery Program, EBMUD, and Viktoria Zoltay, Abt Associates.
City of Seattle. (2006) Seattle, a climate of change: meeting the Kyoto challenge. Climate Action Plan. September.
Available online at http://www.citvofSeattle.net/climate/docs/SeaCAP_plan.pdf.
DEP (New York City Department of Environmental Protection). (2005) Adapting New York City's water supply
and wastewater treatment center to climate change. U.S. Climate Change Science Workshop. November 15.
Available online at http://www.climatescience.gOv/workshop2005/presentations/WA2.5 Lloyd.pdf.
DEP (New York City Department of Environmental Protection). (2006) New York City's wastewater treatment
system. Available online at http://www.nyc.gov/html/dep/pdf/wwsvstem.pdf.
DEP (New York City Department of Environmental Protection). (2008a) Assessment and action plan: a report based
on the ongoing work of the DEP climate change task force. Climate change program. Available online at
http://www.nyc.gov/html/dep/pdf/climate/climate complete.pdf.
DEP (New York City Department of Environmental Protection). (2008b) New York City 2008 drinking water
supply and quality report. Available online at http://www.nyc.gov/html/dep/pdf/wsstateQ8.pdf.
DEP (New York City Department of Environmental Protection). (2008c) Environmental assessment: attachment 1 ~
project description. Available online at http://www.nyc.gov/html/dep/pdf/gilboa/gilboa_proj_desc.pdf.
DEP (New York City Department of Environmental Protection). (2010a) History of New York City's water supply
system. Available online at http://www.nyc.gov/html/dep/html/drinking water/history.shtml.
DEP (New York City Department of Environmental Protection). (201 Ob) The Croton water filtration plant project.
Available online at http://www.nyc. gov/html/dep/html/news/croton. shtml.
Dettinger, MD. (2004) From climate-change spaghetti to climate-change distribution. In: Climate scenarios and
projections: the known, the unknown and the unknowable as applied to California. Aspen Global Change Institute
Workshop held March 11-14, 2004, San Francisco, CA. Available online at
http://www.agci.org/programs/past scientist workshops/about the workshop/sciSess details.php?recordID=88 (as
cited in EBMUD 2009a).
EBMUD (East Bay Municipal Utility District). (2007) All about EBMUD. Available online at
http://ebmud.com/sites/default/files/pdfs/current allaboutebmudni.pdf.
53
-------
EBMUD (East Bay Municipal Utility District). (2008) Strategic plan July. Available online at
http://ebmud.com/sites/default/files/pdfs/Strategic Plan July 2008ni.pdf.
EBMUD (East Bay Municipal Utility District). (2009a). Climate change analysis. In: WSMP 2040—water supply
management program 2040 plan, Appendix C TM-9, October. Available online at
http://www.ebmud.com/sites/default/files/pdfs/WSMP-2040-Appendices-October-2009.pdf.
EBMUD (East Bay Municipal Utility District). (2009b) WSMP 2040—water supply management program 2040
plan. Final program environmental impact report response to comments. SCH #2008052006. October. Available
online at http://www.ebmud.com/sites/default/files/pdfs/WSMP-2040-Main-Document-October-2009.pdf.
EBMUD (East Bay Municipal Utility District). (2009c) Water visions: a clear path to the future. Available online at
http://www.ebmud.com/sites/default/files/pdfs/FY09annuallO O.pdf.
EBMUD (East Bay Municipal Utility District). (2010) Sewer system management plan. Part E8—capacity
management. Available online at http://ebmud.com/sites/default/files/pdfs/New Construction/E8-Capacitv-
Managementpdf.
Freas, K; Bailey, B; Munevar, A; et al. (2008) Incorporating climate change in water planning. Journal of the
American Water Works Association 100:6-98.
Hamlet, AF; Mote, PW; Clark, M; et al. (2005) Effects of temperature and precipitation variability on snowpack
trends in the western United States. J Climate 18(21):4545-4561.
IPCC (Intergovernmental Panel on Climate Change). (2000) Emissions scenarios: summary for policymakers. A
special report of IPCC Working Group III of the Intergovernmental Panel on Climate Change. Available online at
www.ipcc.ch/pdf/special-reports/spm/sres-en.pdf.
IPCC (Intergovernmental Panel on Climate Change), (2007) Climate Change 2007: impacts, adaptation, and
vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on
Climate Change, eds., Parry, M; Canziani, O; Palutikof, J; et al. Cambridge University Press, Cambridge, United
Kingdom and New York, NY, USA.
IPCC (Intergovernmental Panel on Climate Change). (2008) Climate change and water: IPCC Technical Paper VI.
Available online at http://www.ipcc.ch/pdf/technical-papers/climate-change-water-en.pdf.
LAFCO (Local Agency Formation Commission). (2008) Water and wastewater services: municipal services review
for west Contra Costa County. August. Available online at
http://www.contracostalafco.org/municipal service reviews/west county water wastewater/9.0%20EBMUD%20F
inal.pdf.
Major, DC; Horton, R; Rosenzweig, C. (2007) Integrated modeling project for water quantity and quality: guidelines
for project final report. Climate impact assessment of environmental infrastructure systems. New York City
Department of Environmental Protection. June 29.
Maurer, P; Brekke, L; Pruitt, Y; et al. (2007) Fine-resolution climate projections enhance regional climate change
impact studies. Eos Trans AGU 88(47):504.
McCarthy, JJ; Canziani, OV; Leary, NA; et al, eds. (2001) Climate change 2001: impacts, adaptation, and
vulnerability. Contribution of Working Group II to the third assessment report of the Intergovernmental Panel on
Climate Change. Cambridge, UK, and New York, NY: Cambridge University Press. Available online at
http://www.grida.no/publications/other/ipcc tar/.
54
-------
Means III, EG; Laugier, MC; Daw, JA. (2010) Decision support planning methods: incorporating climate change
uncertainties into water planning. Final report. Prepared for Water Utility Climate Alliance. January. Available
online at http://www.wucaonrine.org/assets/pdf/actions whitepaper 012110.pdf.
Miller, K; Yates, D. (2006) Climate change and water resources: a primer for municipal water providers. Denver,
CO: Water Research Foundation and University Corporation for Atmospheric Research. Available online at
http://www.waterresearchfoundation.org/research/TopicsAndProjects/projectProfile.aspx?pn=2973.
Mote, PW. (2003) Trends in temperature and precipitation in the Pacific Northwest during the twentieth century.
Northwest Sci 77(4):271-282.
Mote, PW; Parson, EA; Hamlet, AF; et al. (2003) Preparing for climatic change: the water, salmon, and forests of
the Pacific Northwest. Climatic Change 61(l-2):45-88.
Mote, PW; Hamlet, AF; Clark, M; et al. (2005) Declining mountain snowpack in western North America. Bull Am
Meteorol Soc 86(l):39-49. Available online at
http://www.livingrivers.org/pdfs/LRlibrarv/ClimateDocs/MoteHamletClarkLettenmaier.pdf.
Mote, PW; Hamlet, AF; Salathe, EP. (2008) Has spring snowpack declined in the Washington Cascades? Hydrol
Earth Syst Sci 12:193-206. Available online at www.hvdrol-earth-svst-sci.net/12/.. Vhess-12-193-2008.html.
NASA (National Aeronautics and Atmospheric Administration). (1999) Scientists prepare New York City for future
climate change. Goddard Institute for Space Studies. Research news June 4, 1999. Available online at
http://www.giss.nasa.gov/research/news/19990604/.
NCDC (National Climatic Data Center). (2010) Climate of California. Climates of the States, Climatography of the
United States No. 60. Available online at http://cdo.ncdc.noaa.gov/climatenormals/clim60/states/Clim_CA__01.pdf.
New York State Climate Office. (2010) The climate of New York. Available online at
http://nysc.eas.cornell.edu/climate of ny.html.
New York Water. (2010) The threat to NYC's drinking water from phosphorus pollution. Available online at
http://www.newvorkwater.org/pdf/phosporousPollutionmar2010 2.pdf.
Northwest Hydraulic Consultants. (2009) Application of dynamically downscaled climate model data to analysis of
hydrologic change in Seattle's Urban Creeks: The Thornton Creek Case Study. Prepared for Seattle Public Utilities.
NYC (New York City) Green Infrastructure Plan: A Sustainable Strategy for Clean Waterways, (2010). Available
online at: http://www.nyc.gov/html/dep/pdf/green_infrastructure/NYCGreenInfrastructurePlan_LowRes.pdf
NYC (New York City) Panel on Climate Change. (2009) Climate risk information. Available online at
http://www.nvc.gov/html/om/pdf/2009/NPCC CRI.pdf.
NYSDEC (New York State Department of Environmental Conservation). (2010) State enforcement targets quality
of water near New York City. Environment DEC. Available online at
http://www.dec.nv.gov/environmentdec/18679.html.
Palmer, RN. (2007) Final report of the climate change technical committee. A report prepared by the Climate
Change Technical Subcommittee of the regional water supply planning process. Seattle, WA. Available online at
http://www.climate.tag.washington.edu/techmemos/Final Report 12-13-07_.pdf.
Parry, ML; O Canziani, JP; Palutikof, C; et al, eds. (2007) Climate change 2007: impacts, adaptation and
vulnerability. Contribution of Working Group II to the fourth assessment report of the intergovernmental panel on
climate change. New York: Cambridge University Press. Available online at http://www.ipcc.ch/ipccreports/ar4-
wg2.htm.
55
-------
PlaNYC. (2007a) Climate change. Reduce global warming emissions by more than 30%. Available online at
http://www.nvc.gov/html/planyc2030/downloads/pdf/report climate change.pdf.
PlaNYC. (2007b) Water network. Available online at
http://www.nyc.gov/html/planyc2030/html/plan/water network.shtml.
PlaNYC. (2008) Sustainable stormwater management plan 2008. Available online at
http://www.nvc.gov/html/planyc2030/downloads/pdf/sustainable stormwater_plan.pdf.
PlaNYC. (2008-2010) Progress reports for 2008 through 2010. Available online at
http://www.nvc.gov/html/planvc2030/html/downloads/download.shtml.
Polebitski, A; Traynham, L; Palmer, RN. (2007a) Technical memorandum #4: approach for developing climate
impacted meteorological data and its quality assurance/quality control. A report prepared by the Climate Change
Technical Subcommittee of the Regional Water Supply Planning Process. Seattle, WA. Available online at
http://www.govlink.org/re gional-water-planning/tecn-committees/climate-change/UWreports/TechnicalMemo4(12-
13-07). pdf.
Polebitski, A; Wiley, MW; Palmer, RN. (2007b) Technical memorandum #2: methodology for downscaling
meteorological data for evaluating climate change. A report prepared by the Climate Change Technical
Subcommittee of the Regional Water Supply Planning Process. Seattle, WA. Available online at
http://www.govlink.org/re gional-water-planning/tech-committees/climate-change/UWreports/TechnicalMemo2(12-
13-07).pdf.
Rosenzweig, C; Major, DC; Demong, K; et al. (2007) Managing climate change risks in New York City's water
system: assessment and adaptation planning. Mitigat Adapt Strat Global Change 12(8):1391-1409.
RWSP (Regional Water Supply Planning). (2010) Regional waiter supply planning. Seattle, WA. Available online
at http ://www. govlink. org/regional-water-planning/index. htm.
Smit, B; Pilifosova, O; Burton, I; et al. (2001) Adaptation to climate change in the context of sustainable
development and equity. In: McCarthy, J; Canziana, N; Leary, NA; et al, eds. Climate change 2001: impacts,
adaptation, and vulnerability, chapter 18. New York: Cambridge University Press; pp 877-912. Available online at
http://www. grida.no/climate/ipcc tar/wg2/pdf/wg2TARchap 18.pdf.
Spartanburg Water. (2009) Lake Blalock buffer management plan. Public works of the city of Spartanburg, SC.
September 2009. Accessed March 10. Available online at http://www.sws-sssd.org/pdfs/lbbmp.pdf.
Spartanburg Water. (2010a) Spartanburg water system/Spartanburg sanitary sewer district service areas. Public
works of the city of Spartanburg, SC. Accessed March 10. Available online at http://www.sws-sssd.org/water-
sewer/index.html.
Spartanburg Water. (2010b) Spartanburg lakes. Public works of the city of Spartanburg, SC. [Accessed March 10]
Available online at http://www.sws-sssd.org/lakes/index.html.
Spartanburg Water. (2010c) Drought Committee summary. Received on April 22 via e-mail from Rebecca West,
Deputy General Manager of Technical and Engineering Services.
Spartanburg Water. (2010d) SWS 10 year Capital Improvement Plan, August 2009. Received on April 22 via e-
mail from Rebecca West, Deputy General Manager of Technical and Engineering Services.
Spartanburg Water. (2010e). Operations Capital Improvement Plan items table. Received on April 22 via e-mail
from Rebecca West, Deputy General Manager of Technical and Engineering Services.
56
-------
SPU (Seattle Public Utilities). (2006a) SPU 2007 water system plan. City of Seattle, Washington. November.
Available online at
http://www.citvofseattle.net/util/About SPUAVaterSvstem/Plans/2007WaterSvstemPlan/index.asp.
SPU (Seattle Public Utilities). (2006b) Water shortage contingency plan: supplement to the Seattle public utilities
2007 water system plan. City of Seattle, Washington. July. Available online at
http://www.citvofseattle.net/util/stellent/groups/public/
ershor 200312021018123.pdf.
SPU (Seattle Public Utilities). (2008) South Fork Tolt watershed management plan. Prepared by Tetra Tech
Infrastructure Group and Triangle Associates. City of Seattle, WA. November. Available online at
http://www.citvofseattle.net/util/stellent/groups/public/(g),spu/(g),ssw/documents/webcontent/spu01 004082.pdf.
SPU (Seattle Public Utilities). (2010a) Water system history. City of Seattle, WA. Available online at
http://www.seattle.gov/util/About SPU/Water System/History & Overview/WATERSYST 2003120209Q8156.as
E-
SPU (Seattle Public Utilities). (2010b) History of the watershed. City of Seattle, WA. Available online at
http://www.seattle.gov/util/About SPU/Water System/Water Sources & Treatment/Cedar River Watershed/COS
O01714.asp.
SPU (Seattle Public Utilities). (2010c) Tolt River watershed. City of Seattle, WA. Available online at
http://www.seattle.gov/util/About SPU/Water System/Water Sources & Treatment/Tolt River Watershed/index.
asp.
SPU (Seattle Public Utilities). (2010d) Tolt treatment facility. City of Seattle, WA. Available online at
http://www.seattle.gov/util/About SPU/Water System/Water Qualitv/Tolt Treatment Facility/index.asp.
SPU (Seattle Public Utilities). (2010e) Demographics and water use statistics. City of Seattle, WA. Available online
at
http://www.seattle.gov/util/About SPU/Water System/History & Overview/DEMOGRAPHI 2003120209Q8145.a
sp_.
SRCC (Southeast Regional Climate Center). (2010) Landrum, South Carolina 1971-2000 Monthly Climate
Summary. Accessed May 3. Available online at http://www.sercc.com/.
Stewart, I.T., D.R. Cayan, and M.D. Dettinger. (2004) Changes in snowmelt runoff timing in western North
America under a 'business as usual' climate change scenario. Clim Change 62:217-232. Available online at
http://meteora.ucsd.edu/cap/stewart clch.pdf.
Stratus Consulting and MWH Global. 2009. Implications of Climate Change for Adaptation by Wastewater and
Stormwater Agencies. Water Environment Research Foundation Report No. CC2R08.
Towey, A. (2010) Personal communication from A. Towey, EBMUD to Viktoria Zoltay, Abt Associates on April 9,
2010.
U.S. EPA (Environmental Protection Agency). (2002) Cases in water conservation: how efficiency programs help
water utilities save money and avoid costs. Available online at
http://www.epa.gov/WaterSense/docs/utilitvconservation 508.pdf.
U.S. EPA (Environmental Protection Agency). (2009a) Proceedings of the first national expert and stakeholder
workshop on water infrastructure sustainability and adaptation to climate change. Office of Water, Washington, DC;
EPA 600/R-09/010. Available online at http://www.epa.gov/nrmrl/wswrd/wqin/wrap/workshop.html.
57
-------
U.S. EPA (Environmental Protection Agency). (2009b) New York City watershed. Region 2. Available online at
http://www.epa.gov/Region2/water/nycshed/.
U.S. EPA (U.S. Environmental Protection Agency). (2010) Climate change vulnerability assessments: A review of
water utility practices. Office of Water, Washington, DC; EPA/800/R-10/001. Available at
http://water.epa.gov/scitech/climatechange/upload/Climate-Change-Vulnerabilitv-Assessments-Sept-2010.pdf.
USGCRP (U.S. Global Change Research Program). (2009) Global climate change impacts in the United States.
Available online at http://www.globalchange.gov/publications/reports/scientific-assessments/us-impacts.
USGS (U.S. Geological Survey). (2009) Taste and odor occurance in Lake William C. Bowen and Municipal
Reservoir #1, Spartanburg County, South Carolina. USGS Fact Sheet 2009-3043. Available online at
http://pubs.usgs.gov/fs/2009/3043/.
UW-CIG (University of Washington Climate Impacts Group). (2010a) About Pacific Northwest climate. Joint
Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle. Available online at
http://cses.washington.edu/cig/pnwc/pnwc.shtml.
UW-CIG (University of Washington Climate Impacts Group). (201 Ob) Climate change. Joint Institute for the Study
of the Atmosphere and Ocean, University of Washington, Seattle. Available online at
http://cses.washington.edu/cig/pnwc/cc.shtml.
UW-CIG (University of Washington Climate Impacts Group). (2010c) Case study: Seattle public utilities. Joint
Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle. Available online at
http://cses.washington.edu/cig/fpt/casestudvspu.shtml.
WA DOE (Washington State Department of Ecology). (2001) Appendix B: Summary of major ASR projects in
Washington. Appendix to ASR 2001 Report to the Legislature.
http://www.ecv.wa.gov/programs/wr/asr/images/pdf/ASRLegRptApdx.pdf.
Wallis, MJ; Ambrose, MR; Chan, CC. (2008) Climate change: charting a water course in an uncertain future.
JAWWA 100(6):70-79. http://www.ebmud.com/sites/default/files/pdfs/Journal-06-08 O.pdf.
Water-technology.net. (2010) Croton water filtration plant, New York, USA. Available online at http://www.water-
technologv.net/projects/crotonfiltration/.
West, R. (2010) Deputy General Manager of Engineering & Technical Services, Spartanburg Water. Personal
communication on April 1. 2010
WRCC (Western Regional Climate Center). (2010) Western U.S. climate historical summaries. Available online at
http://www.wrcc.dri.edu/Climsum.html.
WUCA (Water UtilityClimate Alliance). (2010) About us. Accessed May 3, 2010. Available online at
http://www.wucaonline.org/html/about us.html.
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