DRAFT EPA/600/R-10/077 A
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External Review Draft
vvEPA
Climate Change Vulnerability Assessments:
Four Case Studies of Water Utility Practices
NOTICE
THIS DOCUMENT IS A PRELIMINARY DRAFT. It has not been formally released by
the U.S. Environmental Protection Agency and should not at this stage be construed to
represent Agency policy. It is being circulated for comment on its technical accuracy and
policy implications.
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 is distributed solely for the purpose of predissemination peer review under
applicable information quality guidelines. It has not been formally disseminated by EPA. It
does not represent and should not be construed to represent any Agency determination or policy.
Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
This document is a draft for review purposes only and does not constitute Agency policy.
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TABLE OF CONTENTS
LIST OF TABLES iv
LIST OF FIGURES iv
PREFACE v
AUTHORS AND CONTRIBUTORS vi
EXECUTIVE SUMMARY vii
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 12
2.4.2. Hydropower Generation 12
2.4.3. Water Supply 13
2.4.3.1. Increased Demand 14
2.4.3.2. Temporal Shift in Runoff 14
2.4.3.3. Decrease in Annual Precipitation 15
2.4.4. Water Quality 15
2.5. Application of Vulnerability Assessment Information 16
3. New York City Department of Environmental Protection 18
3.1. Background 18
3.2. Description of the Water System 20
3.2.1. Water Supply System 20
3.2.2. Wastewater System 22
3.3. Climate Change Projections and Risks 22
3.4. Climate Change Vulnerability Assessments 25
3.5. Application of Vulnerability Assessment Information 28
3.5.1. Decreasing Turbidity 28
3.5.2. Minimizing Flooding 28
3.5.3. Minimizing Supply and Demand Imbalances 29
3.5.4. Combating Combined Sewer Overflows 29
3.5.5. Adapting to Flood Risk 30
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TABLE OF CONTENTS (continued)
4. Seattle Public Utilities 31
4.1. Background 31
4.2. Description of the Water System 32
4.2.1. Water Supply System 32
4.2.2. Wastewater System 36
4.3. Climate Change Projections and Risks 36
4.4. Vulnerability Assessment 40
4.4.1. Water Supply 40
4.4.2. Water Demand 41
4.4.3. Storms and Runoff. 41
4.5. Application of Vulnerability Assessment Information 42
4.5.1. Water Supply 42
4.5.2. Storms and Runoff. 43
5. Spartanburg Water 44
5.1. Background 44
5.2. Description of the Water System 44
5.2.1. Water Supply System 44
5.2.2. Wastewater System 46
5.3. Climate Change Projections and Risks 47
5.4. Climate Change Vulnerability Assessments 48
5.4.1. Water Quantity 48
5.4.2. Water Quality 49
5.4.3. Infiltration/Inflow 50
5.5. Application of Vulnerability Assessment Information 50
6. Summary 53
References 55
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LIST OF TABLES
1. Key attributes of water utility case studies 3
2. Projected baseline climate and mean annual changes for New York City 23
3. Projections of changes in annual mean temperature and precipitation for the
2020s, 2040s, and 2080s 37
LIST OF FIGURES
1. Location of water utilities for case studies 3
2. East Bay Municipal Utility District (EBMUD) service area and ultimate service
boundary 7
3. New York City Department of Environmental Protection (DEP) system overview 19
4. Seattle public utilities service area 34
5. South Fork Tolt watershed 35
6. Reservoirs and watersheds of the Spartanburg water system 45
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PREFACE
The U.S. Environmental Protection Agency's (EPA's) Global Change Research Program
(GCRP), located within the Office of Research and Development, works to define critical issues
and information needs, and to provide information and tools to build the capacity of EPA
program and regional offices, water managers, and other decision-makers to assess and respond
to global change. The GCRP has four focus areas: air quality, water quality, aquatic ecosystems,
and human health. The Program's focus on water quality is consistent with the Research
Strategy of the U.S. GCRP, the federal umbrella organization for climate change science in the
U.S. government, and is responsive to EPA's mission and responsibilities as defined by the
Clean Water Act, Safe Drinking Water Act, and other federal laws.
This report presents a series of 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. 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. The issue of climate change is complex and will require ongoing
attention and study. The authors hope that the examples presented in this report can in some way
inform or otherwise support other utilities and water managers faced with this challenge.
Peter Preuss, PhD.
Director
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
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AUTHORS AND CONTRIBUTORS
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
REVIEWERS
The authors are very grateful for the thoughtful comments and suggestions from Meredith
Warren and Y. Jeffrey Yang on an earlier draft of this report.
ACKNOWLEDGMENT S
This report would 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 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, U.S. EPA and Y. Jeffrey Yang, U.S. EPA for their many insights and
suggestions that contributed to this report.
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EXECUTIVE SUMMARY
There is growing concern about the potential effects of climate change on the quantity,
quality, timing, and demand for water. 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, 2009b). One outcome of this
workshop was that it would be useful to develop case studies of successful adaptation projects
and activities to help individual utilities learn from each other.
This report presents a series of 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. Rather, its purpose is to illustrate a range of issues and current
approaches taken by leading water utilities to understand and respond to climate risk.
The following four utilities are featured 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 four case studies presented in this report were selected not because they are typical
of how climate change is being addressed by water utilities in the United States but, rather,
because they are among the leaders in adaptation. The selected case studies also differ in terms
of their geographic location, size, and the types of impacts from climate change they may face.
EAST BAY MUNICIPAL UTILITY DISTRICT
East Bay Municipal Utility District (EBMUD) used an elaborate policy analysis when
designing its Water Supply Management Program 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 five portfolios under climate change scenarios. EBMUD
applied a "bottom-up" approach for the analyses by identifying climate factors most likely to
Existing supplies were estimated to be sufficient during normal and wet years.
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affect the system's reliability and testing the system's 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 2004 or a 20% decrease in precipitation) (EBMUD, 2009a). EBMUD's analyses reaffirmed
the need for a strategy that is flexible and adaptable to observations in further changes in climate
and to refinements in climate change projections (EBMUD, 2009b).
NEW YORK CITY DEPARTMENT OF ENVIRONMENTAL PROTECTION
To analyze vulnerability, New York City Department of Environmental Protection (DEP)
examined potential impacts on the availability of water, turbidity, and eutrophication. The
vulnerability analyses identified a number of potential risks to New York City's water supplies
and quality, including increased demand, reduced inflows during the spring thaw season, and
increased risk of combined sewer overflows, nutrient loadings, and eutrophi cation. In addition,
sea level rise and consequent increased salinity levels in the Hudson River may pose risks to the
city's drainage and wastewater treatment systems. DEP has identified a wide array of initiatives
to reduce risks from these potential outcomes, including developing a modeling-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 reservoir during turbidity events, more
frequently cleaning and maintaining sewers and catch basins, expanding 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, such as increased heavy precipitation events and urban heat island effect, as part of its
broad, city-wide effort to better manage stormwater.
SEATTLE PUBLIC UTILITIES
Seattle Public Utilities (SPU) appears to be the only one of the four case utilities that
directly used the results to make an adaptation decision. SPU has worked closely with the
Climate Impacts Group (CIG) at the University of Washington (UW) since 2002 on two different
studies to assess climate change impacts. In the most recent study, UW-CIG selected global
climate models (GCMs) to capture a range of conditions, statistically downscaled them, and ran
the outputs through a hydrology model. These results were inputs into SPU's water supply
planning model. SPU also used the downscaled data to project changes in demand for water.
All of the climate change scenarios resulted in an estimated decrease in water supplies. The
most direct use of the vulnerability assessment by SPU was for the water planners to test the
effectiveness of different operational assumptions. SPU also identified more far-reaching
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adaptations to use in future decades in case demand exceeds water supplies, either because of
population growth or climate change.
SPARTANBURG WATER
Spartanburg Water is an example of a relatively small utility that was unable to conduct
quantitative vulnerability assessments (e.g., model-based assessments) but nonetheless was able
to use information on climate change and recent extreme climate events to inform and allow for
the consideration of climate change in management decisions. Recent extreme weather events
perhaps had the greatest influence on Spartanburg Water's consideration of climate change risks.
South Carolina has experienced several extreme droughts and hurricanes in recent years and
anticipates that climate change will exacerbate these extreme events. In addition, with lower low
flows in receiving streams, the wastewater treatment plants may be required to upgrade to reduce
their discharge loads. More intense precipitation could result in greater pollutant loadings to the
receiving streams.
In response to all of these concerns and planning for increases in population, Spartanburg
Water made a number of changes in its infrastructure and operations. Recent concerns about
droughts 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 when installing new pipes, kept the old ones for additional capacity. These
adaptations are consistent with Spartanburg Water's experience with recent extreme events and
concerns about population growth, and climate change provides additional justification for these
measures.
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:
• For the four utilities researched for this report, conducting climate change vulnerability
assessments appears to have increased awareness of climate change risks, informed
decision making, and provided support for adaptation measures. These case studies
illustrate the wide range of issues and constraints faced by utilities and approaches for
considering adaptation to climate change in a holistic context, taking into account all
factors affecting system performance.
• Utilities have benefitted by working with climate change researchers. SPU collaborated
with the Climate Impacts Group at the University of Washington, DEP collaborated with
Columbia University and the City University of New York, and EBMUD used an
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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 information on climate change risks.
• 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 particular
elements of its water resource system could be affected by climate change. SPU and
DEP conducted what are often referred to as "top-down" approaches driven by climate
change scenarios and models.
• The utilities used models to manage and understand the dynamics of their systems. All of
the case studies except Spartanburg used their 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, were also necessary.
• A review of literature on climate change and understanding of how recent extreme events
could become worse in the future informed Spar tanburg's consideration of climate
change in its decision making. This suggests that while modeling the potential effects of
climate change on a system appears to be useful in providing insights about vulnerability,
it is not necessary. The Spartanburg case study demonstrates that utilities lacking the
financial and staff resources to support detailed modeling studies can still considerably
reduce their vulnerability to the potential impacts of climate change by increasing their
knowledge of projected climate change and associated risks.
• Utilities expressed an interest in obtaining better information on climate change, and that
their needs are reflected in future research. They particularly requested information on
projections at the spatial and temporal scales in which they operate, the probability of
specific changes in climate, and guidance on appropriate climate change parameters and
scenarios to consider and plan for in their regions. It was recommended that a central
repository of data be created to support climate change and adaptation analysis. Utilities
need transparent information on how data are collected and what their appropriate uses
are.
• Overall, the case studies presented in this report suggest that while there is uncertainty
about how climate will change in different regions of the country, through analysis and
study, utilities are able to improve their understanding of the risks they will likely face
from climate change. This will help them make informed decisions about how to best
adapt to climate change so as to minimize their potential losses.
• The results of vulnerability assessments by the four utilities presented in this report were
used in different ways to inform and support adaptation. Seattle responded specifically
to the results of the vulnerability analysis by evaluating the impact that conservative
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assumptions have on reservoir management. Vulnerability assessments conducted by the
other utilities appeared to have increased awareness of climate change risks, informed
decision making, and provided support for adaptation measures.
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1 1. INTRODUCTION
2 There is growing concern about the potential effects of climate change on the quantity,
3 quality, timing, and demand for water. In particular, decisions about water infrastructure have
4 long-term implications because the infrastructure we build today will likely be in place for
5 decades. In 1997, the American Water Works Association (AWWA) issued a statement
6 expressing the need for water utilities to begin planning for consequences of climate change
7 (AWWA, 1997). In 2004, AWWA teamed with the National Center for Atmospheric Research
8 to publish guidance for municipal utilities to address climate change (Miller and Yates, 2006).
9 Three years later, eight major municipal water utilities formed the Water Utilities Climate
10 Alliance (WUCA) to "provide leadership and collaboration on climate change issues affecting
11 the country's water agencies" (WUCA, 2010).
12 Vulnerability to climate change, as defined by the Intergovernmental Panel on Climate
13 Change (IPCC), refers to the exposure, sensitivity, and adaptive capacity of systems to climate
14 change (Smitetal., 2001). Exposure consists of the type of change experienced by a system. A
15 coastal city may be exposed to a 3-foot sea level rise, while an inland city will not. Sensitivity is
16 the effect that climate change can have on a system assuming no planned adaptation. For
17 example, climate change is projected to reduce the growth of many crops but increase the growth
18 of others. The sensitivity of these crops to climate change differs. Adaptive capacity refers to
19 the potential or ability of a system to adapt to the effects of climate change (Smit et al., 2001).
20 The adaptive capacity of a system is important, for example, in distinguishing the vulnerability
21 of wealthy and poor societies or human systems versus ecosystems. Wealthier societies, in
22 general, have greater adaptive capacity and, thus, on average, are considered less vulnerable to
23 climate change than poorer societies (Parry et al., 2007).
24 A number of water utilities have begun to assess the potential vulnerability of their
25 systems to climate change. Many are considering whether their infrastructure or operations
26 should be changed now or in the future to adapt to climate change.
27 In 2009, the U.S. Environmental Protection Agency (EPA) sponsored the First National
28 Expert and Stakeholder Workshop on Water Infrastructure Sustainability and Adaptation to
29 Climate Change (U.S. EPA, 2009b). This workshop examined how to provide useful
30 information to water and wastewater utility managers on adapting to the impacts of climate
31 change. One outcome of the workshop was that it would be useful to develop case studies of
32 successful adaptation projects and activities to help individual utilities learn from each other.
33 This report presents a series of case studies describing the approaches taken by four water
34 utilities in the United States to assess their vulnerability to climate change. The report is not
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1 intended to be a comprehensive listing of assessment approaches or utilities conducting
2 vulnerability assessments. Rather, its purpose is to illustrate a range of issues and current
3 approaches taken by selected utilities that are leaders in climate adaptation to understand and
4 respond to climate risk. The issue of climate change is complex and will require ongoing
5 attention and study. We hope the information gleaned from these case studies will be of use to
6 water utilities and other members of the water resources community in illustrating a range of
7 vulnerability studies being applied to guide adaptation decision making. This report is also
8 intended to help identify the types of technical assistance most needed to support such
9 assessments.
10 A companion report has been prepared for the EPA Offices of Water and Research and
11 Development, Climate Change Vulnerability Assessments: A Review of Water Utility Practices
12 (Stratus Consulting, 2010). The purpose of that report is to identify and categorize the models
13 and techniques being used by eight water utilities to understand their vulnerability to climate
14 change. This report provides an in-depth examination of three of the eight utilities discussed in
15 the previous report, plus one that was not.
16
17 1.1. SELECTION OF CASE STUDIES
18 Many water utilities are active in climate adaptation and could have been included in this
19 report. It was necessary for practical reasons, however, to limit the scope of this report to just
20 four utilities. The four utilities featured in this report are (Figure 1)
21
22
23 • East Bay Municipal Utility District (EBMUD) in Contra Costa and Alameda
24 Counties, California;
25 • New York City Department of Environmental Protection (DEP) in New York, New
26 York;
27 • Seattle Public Utilities (SPU) in Seattle, Washington; and
28 • Spartanburg Water (Spartanburg, South Carolina).
29
30
31 These utilities were selected because they appear to be leaders in climate adaptation and
32 because they differ in terms of their geographic location, size, and the types of impacts from
33 climate change they may face (Table 1). Case studies are located in the northwestern,
34 southwestern, northeastern, and southeastern United States. Three of the four serve over a
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Contra Costa
and Alameda
counties, CA
YV^f v^
^ \ J /W^w
( f^y \ I ^W New York, NY
Spartanburg, SC
Figure 1. Location of water utilities for case studies.
Table 1. Key attributes of water utility case studies
Utility
EBMUD
DEP
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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1 million people. The smaller Spartanburg Water was selected because of its size and because it
2 took a qualitative approach to understanding its vulnerability to climate change. Western utilities
3 are mainly concerned about potential changes in the timing of and reductions in runoff, while the
4 eastern utilities are concerned about changes in extreme events and consequences of these events
5 for water quantity, quality, and the performance of their systems.
6 Each of the selected utilities has examined or is examining the vulnerability of their
7 system to climate change. The methods used span a range from detailed, quantitative analyses to
8 a more qualitative approach for examining climate change and learned lessons from recent
9 extreme events. All four utilities have also made changes to planning, operations, or
10 infrastructure that, if not driven by the results of their analyses, are at least consistent with
11 adapting to climate change. While these four case studies should not be considered
12 representative of how all utilities are considering climate change, they can provide insight into
13 how information on vulnerability to climate change is being developed and used.
14
15 1.2. DATA COLLECTION
16 The information presented in this report was collected from publically available
17 documents and interviews with utility staff. Specifically, we focused on
18
19
20 • Background of the utility—e.g., location, size of utility;
21 • Description of the utility, including the water supply (which includes provision of
22 drinking water) and wastewater system;
23 • Climate change projections and why the utility was interested in vulnerability to climate
24 change;
25 • Approach for conducting vulnerability assessment, including scenarios, assessment
26 methods, and results; and
27 • Discussion of application of vulnerability assessment information.
28
29
30 Individual utility case studies are presented in the following four chapters. To the extent
31 possible, we have attempted to present each case study in a consistent level of detail. The final
32 chapter of this report presents summary observations and insights gained from these four case
33 studies.
34
35
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1 2. EAST BAY MUNICIPAL UTILITY DISTRICT
2 East Bay Municipal Utility District (EBMUD) is a public water utility established in
3 1923 under the California Municipal Utility District Act. Within the EBMUD service area,
4 Special District Number 1 (SD1) was established in 1944 to treat wastewater.
5
6 2.1. BACKGROUND
7 EBMUD provides water to an estimated 1.3 million people in 35 communities in
8 Alameda and Contra Costa Counties in the East San Francisco Bay, as well as industrial and
9 commercial water users (Wallis et al., 2008; EBMUD, 2009b). It produces an average of
10 220-million gallons per day (mgd) of drinking water in nondrought years. The total service area
9 _
11 is approximately 335 mi . EBMUD also provides wastewater services for approximately
12 640,000 customers west of Oakland/Berkeley Hills (EBMUD, 2009b) in an 83-mi2 component of
13 the EBMUD service area.
14 Diverse topography and maritime influences in California and the San Francisco Bay area
15 contribute to a varied climate within the EBMUD service area. The Coast Range runs parallel to
16 the coastline from Oregon to north of the Los Angeles Basin and is generally no more than
17 50 miles wide (WRCC, 2010). A break in the Coast Range at San Francisco Bay allows the
18 inflow of marine air to the interior of the State under specific circulation patterns (WRCC, 2010).
19 The Coast Range merges with the Cascade Range in the northern part of the State creating a
20 200-mile-wide area of rugged terrain (WRCC, 2010). The Cascades then reach southeast and
21 merge into the Sierra Nevada, which continues to parallel the coast. Between these two ranges,
22 there is the Central Valley. This flat, 45-mile-wide valley is closed off by the meeting of the
23 Sierra Nevada and Tehachapi Mountains, which reach southwest to meet the Coast Range
24 (WRCC, 2010).
25 West of these mountain ranges, there is a predominantly maritime climate dominated by
26 the Pacific Ocean. This area experiences warm winters, cool summers, small daily and seasonal
27 temperature ranges, and high relative humidities (WRCC, 2010). East of the mountain ranges,
28 there is a continental desert climate with warmer summers, colder winters, greater daily and
29 seasonal temperature ranges, and generally lower relative humidities (WRCC, 2010). In the
30 transition zone between these two areas, climate depends on how the local topography influences
31 circulation patterns (WRCC, 2010). The difference between Oakland, California, on the San
32 Francisco Bay, and Livermore, California, just 30 miles inland, illustrates the climate variability
33 within the EBMUD service area. The average maximum July temperatures are 72°F and 89°F in
34 Oakland and Livermore, respectively (WRCC, 2010).
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1 Snow melt from the Sierra Nevada feeds most major streams well into or throughout the
2 arid summer months. Dams serve a dual purpose of providing a water supply through the dry
3 part of the year and flood control during the winter and spring. In Oakland, the average total
4 precipitation is 23 inches while in Livermore it is 14 inches (NCDC, 2010). All of the
5 precipitation in Oakland falls as rain while Livermore, on average, receives approximately
6 0.1 inch of snow (NCDC, 2010).
7 Climate change has been documented in this region. In the second half of the twentieth
8 century, a 2°C rise in winter temperature was observed in the Sierra Nevada (EBMUD, 2009a).
9 With a 5°C rise in temperature, the April 1 snow-covered area could decrease by as much as 50%
10 (California Department of Water Resources [C A DWR] Report).
11
12 2.2. DESCRIPTION OF THE WATER SYSTEM
13 2.2.1. Drinking Water Supply System
14 2.2.1.1. Water Sources
15 The main water source for EBMUD is the Mokelumne River Watershed, which is located
16 approximately 100 miles northeast in the Sierra Nevada (Figure 2). Approximately 90% of the
9
17 water supply originates from this 577-mi area (Wallis et al., 2008). The remaining water supply
18 is from runoff in protected watershed areas of the East Bay. During dry years, evaporation can
19 exceed runoff, resulting in no net water supply in those years (EBMUD, 2009b).
20 Most of the Mokelumne River Watershed is undeveloped (approximately 75% of its land
21 is forested) and is located within national forests. Precipitation is highly variable in the
22 watershed, with 14 of the last 20 years having below-normal precipitation to being critically dry.
23 Precipitation also varies considerably by season, with the most precipitation from November to
24 May and the least precipitation from June to September. Peak flows are during winter storms
25 and the spring snowmelt; minimum flows are in the late summer and fall (EBMUD, 2009b).
26 Approximately 63% of the annual average runoff occurs during the spring snowmelt from April
27 to July (EBMUD, 2009a).
28 Two reservoirs on the Mokelumne River provide water storage, flood protection,
29 recreation, hydropower, and resource management for a downstream fish hatchery. Flow into
30 Pardee Reservoir is regulated by a number of upstream reservoirs. Pardee Reservoir has a
31 maximum storage capacity of 197,950 acre-feet. The Mokelumne Aqueducts (three closed-pipe
32 aqueducts) stretch 91 miles across the Sacramento/San Joaquin River Delta to convey water from
33 the Pardee Reservoir to the EBMUD service area. The remaining water from the Pardee
34 Reservoir flows to the Camanche Reservoir, which has a maximum storage capacity of
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V~^E:
.;
Figure 2. East Bay Municipal Utility District (EBMUD) service area and
ultimate service boundary.
Source: EBMUD (2009b).
1 417,120 acre-feet. Water from the Pardee Reservoir is used to meet the demands of the EBMUD
2 service area, while the Camanche Reservoir is managed to meet EBMUD's obligations to
3 downstream fisheries and senior water rights (EBMUD, 2009b).
4 EBMUD has water rights and capacity to use and/or divert to storage up to 325 mgd of
5 water from the Mokelumne River. However, the actual flow that can be diverted is determined
6 by the amount of runoff and streamflow, upstream and downstream senior water rights, and
7 storage capacities. In addition, the Camanche Reservoir must also provide releases for fisheries
8 downstream and ensure the availability of up to 200,000 acre-feet of flood control storage during
9 winter months (EBMUD, 2009b). There are five terminal reservoirs that have a combined
10 capacity of 155,150 acre-feet (EBMUD, 2007). In addition to storing water from the Pardee
11 Reservoir, the terminal reservoirs in the East Bay capture runoff from protected areas of the East
12 Bay Watershed. The terminal reservoirs are operated to maintain 180 days of raw water supply
13 (EBMUD, 2009b).
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1 Two additional water sources will be available starting mid-2010 to supplement water
2 supplies during dry years (Chan, 2010). Up to 100 mgd of raw surface water will be available
3 from the Sacramento River via the Freeport Regional Water Project. This will meet
4 approximately 22% of water needs during dry years. EBMUD estimates that it will use this
5 water source approximately 3 out of every 10 years (EBMUD, 2009a). The other new source
6 will be from the first phase of the Bayside Groundwater Project. Treated drinking water will be
7 injected into the south East Bay Plain Basin during wet years and extracted during dry years.
8 The withdrawal permit provides for up to an annual maximum of 1 mgd of water with an
9 extraction rate of 2 mgd for a portion of a "particular drought year" (EBMUD, 2009b).
10
11 2.2.1.2. Water Distribution
12 The water distribution system is composed of approximately 120 pressure zones (located
13 at elevations ranging from sea level to 1,450 ft) and approximately 4,100 miles of pipe. About
14 half of the water is distributed by gravity flow. In addition, there are approximately
15 140 pumping plants and 170 treated water storage tanks (EBMUD, 2007).
16 Water conveyed to EBMUD either is treated at one of three inline-filtration treatment
17 plants and distributed or is stored in the East Bay terminal reservoirs. Three additional drinking
18 water treatment plants are supplied by two terminal reservoirs. These three plants have full
19 conventional treatment, with two of them also providing ozonation.
20
21 2.2.1.3. Water Use
22 The water use in the EBMUD service area is approximately 92% residential,
23 7% commercial, and 1% industrial and public authority use (EBMUD, 2007). The majority of
24 water provision services are funded by user fees (approximately 75%) with the remaining
25 revenue coming from capital contributions, investment, taxes, hydropower generation, and other
26 sources (EBMUD, 2009c).
27
28 2.2.1.4. Demand Management
29 Programs for managing demand include water rationing, conservation, and reuse. In
30 calculating water availability, EBMUD follows its Water Supply Availability and Deficiency
31 Policy. According to this policy, the maximum rationing (i.e., mandatory water use reduction)
32 during droughts is a 25% reduction in total customer demand, while continuing to provide water
33 to fisheries and other downstream obligations (EBMUD, 2009b). Varying levels of rationing are
34 imposed, depending on the existing and projected extent of the drought and how the levels differ
35 across customer categories. Conservation measures include leak detection and repair in the
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1 distribution system, customer incentives for water reduction, and customer education and
2 outreach on water conservation. EBMUD reuses water by providing treated wastewater and
3 untreated raw water from local runoff for irrigation and in-plant processes (EBMUD, 2009b).
4 Approximately 9.3 mgd of water are recycled (Towey, 2010).
5
6 2.2.2. Wastewater System
7 Nine communities within SD1 have wastewater collection systems that discharge into
8 one of EBMUD's five interceptor sewer trunk lines (EBMUD, 2010). The interceptors have a
9 capacity of 760 mgd of water. On average, the EBMUD wastewater treatment plant (WWTP) in
10 Oakland receives 80 mgd from the interceptors (EBMUD, 2007). The Oakland WWTP has the
11 capacity for up to 320 mgd of primary treatment, 168 mgd of secondary treatment, a short-term
12 hydraulic peak of 415 mgd during wet weather events, and 11 million gallons of storage
13 (EBMUD, 2007; Cheng, 2010). Treated wastewater is discharged 1 mile off the coast through a
14 deep-water outfall into San Francisco Bay (LAFCO, 2008; EBMUD, 2007).
15 By-products from WWTP operations are used in two forms: biosolids are used as a soil
16 amendment or alternative daily cover at landfills, and methane gas provides energy needed for
17 operations (EBMUD, 2007). In addition, as part of its wastewater source control and pollution
18 prevention activities, EBMUD collects concentrated domestic waste, oil, and grease from
19 restaurants, and other highly organic waste streams to produce methane gas, while decreasing the
20 organic content of the wastewater stream (EBMUD, 2007). Overall, self-produced methane gas
21 provides up to 90% of the Oakland WWTP's power supply (Cheng, 2010).
22 Since 1979, EBMUD and local communities have addressed rainwater infiltration and
23 inflow in the wastewater collections system resulting from deteriorated pipes and improper storm
24 drain connections. As part of the East Bay Infiltration/Inflow Correction Program, EBMUD
25 constructed three wet-weather treatment plants, two storage basins, 7.5 miles of new interceptor
26 lines, and an expanded Oakland WWTP. Communities have spent more than $460 million on
27 improvements for their wastewater collection systems (EBMUD, 2007).
28 In 2009, approximately 69% of the revenue for wastewater services came from user fees
29 (53% from wastewater, 16% from wet-weather facilities), and the remaining came from capital
30 contributions, resource recovery, taxes, investments, and other sources (EBMUD, 2009c).
31
32 2.3. CLIMATE CHANGE PROJECTIONS AND RISKS
33 Climate change information used by EBMUD to evaluate vulnerability to climate change
34 included the Fourth Assessment Report of the Intergovernmental Panel on Climate Change
35 (IPCC) and two state-level studies that modeled the effects of climate change on water resources
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1 (EBMUD, 2009a). Model projections from the IPCC suggest that temperatures in the western
2 United States could rise 2.0-7.5°C by the end of this century (IPCC, 2007, as cited in Wallis et
3 al., 2008). In a summary of northern California climate change studies, Dettinger (2004, as cited
4 in EBMUD, 2009a) provides a range of a 2.0-6.0°C increase in temperature and either a 20%
5 increase or decrease in precipitation. In addition, rising temperatures are expected to cause
6 precipitation to fall more often as rain, decreasing water storage in snowpacks and causing spring
7 runoff to occur earlier. The temperature rise will extend the growing season by about
8 19-28 days, with more frequent and longer heat waves (Wallis et al., 2008). Sea level is
9 expected to rise another 0.6-1.9 ft by the end of the century (IPCC, 2007, as cited in Wallis et
10 al., 2008). This will affect the frequency and severity of flooding in coastal areas, including the
11 flood-prone Sacramento/San Joaquin River Delta, where three EBMUD water transmission
12 aqueducts cross (Wallis et al., 2008).
13 EBMUD reviewed two state-level climate change studies—one by the California Energy
14 Commission's Public Interest Energy Research (PIER) and the California Climate Change
15 Center (CCCC), and one by the CA DWR. A review of both state-level studies by EBMUD
16 concluded that the studies yielded the following similar but uncertain results (EBMUD, 2009a):
17
18
19 • Temperature increases will be significant, but the magnitude of change is uncertain.
20 • Snowpack volume will decrease.
21 • Snow will melt earlier.
22 • The direction and amount of change in total annual precipitation is inconclusive.
23 • Drought impacts are also inconclusive, but some scenarios predict increased frequency
24 and longer-duration droughts.
25 • There will be a general increase in climate variability.
26
27
28 With a growing awareness of climate change and its potential effects on water resource
29 management, EBMUD started following climate change research, collecting information about
30 projected regional climate change, gathering environmental data, and networking locally and
31 nationally with others in the water community (Wallis et al., 2008; Chan, 2010). EBMUD staff
32 presented these efforts to the Board of Directors and at an annual business forum attended by the
33 Board of Directors and key stakeholders (Wallis et al., 2008).
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1 In addition, EBMUD gauged customer opinion about climate change in an annual
2 customer survey. The survey showed that almost 75% of respondents thought that climate
3 change will be an issue for water suppliers within the next 50 years, and the effect of climate
4 change on water availability was of "highest concern" for 46% of the respondents (Wallis et al.,
5 2008; Chan, 2010).
6 In mid-2007, EBMUD established an official utility-wide management approach for
7 addressing climate change and formed a cross-departmental climate change committee. The
8 committee's primary tasks include keeping up to date on climate change science, evaluating the
9 potential effects of climate change, reviewing Mokelumne River Watershed data to determine
10 changes in trends, assessing water supply and infrastructure vulnerabilities, integrating climate
11 change in planning and budgeting, and developing adaptation and mitigation strategies. By
12 2008, the EBMUD strategic plan incorporated climate change as one of the strategies for
13 meeting long-term water supply goals. Strategies included developing and implementing a
14 Climate Change Monitoring and Response Plan and mitigating greenhouse gas emissions across
15 departments (Wallis et al., 2008). While climate change-related activities, such as mitigating
16 greenhouse gas emissions are cross-departmental, vulnerability assessment efforts have focused
17 primarily on the water supply system (Cheng, 2010).
18
19 2.4. CLIMATE CHANGE VULNERABILITY ASSESSMENTS
20 EBMUD identified four key areas of potential vulnerability to climate change:
21 (1) flooding and sea level rise, (2) hydropower generation, (3) water supply and demand, and
22 (4) water quality (Wallis et al., 2008). Since 2006, EBMUD has conducted qualitative
23 assessments and sensitivity analyses to examine these vulnerabilities and their impacts on the
24 drinking water system. The most extensive and quantitative vulnerability analysis was done as
25 part of the Water Supply Management Program (WSMP) 2040. Vulnerability analyses for the
26 WSMP 2040 focused on water supply, water demand, and the effect of temperature on water
27 quality. Qualitative and less formal assessments have been performed for flooding, sea level
28 rise, and power generation. EMBUD also participates in local and national conferences and
29 workgroups, such as the U.S. Environmental Protection Agency (EPA) Climate Ready Water
30 Utilities Working Group, and currently, is working with the EPA and the Water Research
31 Foundation on developing vulnerability and risk assessment tools to assist other water utilities in
32 conducting climate change analyses (Chan, 2010).
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1 2.4.1. Flooding and Sea Level Rise
2 EBMUD expects that flooding may increase as a result of the more frequent extreme
3 weather events that are predicted with climate change. To assess the effect of more extreme
4 weather events on the potential for flooding in urbanized areas downstream of the Camanche
5 Reservoir, EBMUD modeled the water supply system with a 3°C rise and 1997 precipitation
6 levels (the wettest year in the last quarter century due to El Nino). The study used the daily
7 operational model for the EBMUD water system (Chan, 2010). Results showed that the peak
8 water release from the Camanche Reservoir would have had to be three times as much as it was
9 in 1997 to prevent flooding (Wallis et al., 2008).
10 In addition to more extreme weather events, sea level rise may contribute to increased
11 coastal flooding. A 1-foot rise in sea level could cause the 1 in 100-year storm surge flood event
12 to occur once every 10 years (Wallis et al., 2008). The aging levee system of the flood-prone
13 and earthquake-prone Sacramento/San Joaquin River Delta is an existing vulnerability that will
14 be exacerbated by rising sea levels. The flooding could disrupt water delivery for months as it
15 did in 2004, when a single levee breach caused flooding that submerged the aqueducts for more
16 than 4 months.
17 As part of WSMP 2040, EBMUD reviewed the two state-level climate change studies
18 (Section 2.3, above) and found that they sufficiently document current conditions and existing
19 risks, including the susceptibility of the raw-water system to levee failures, earthquakes, and
20 potential failure scenarios. However, the interactions of vulnerabilities, such as the effects of sea
21 level rise on levee failure, have not been characterized. CA DWR is drafting a Delta Risk
22 Management Strategy, and its first report will provide discrete probabilities of levee failure
23 considering several climate change and sea level-rise scenarios. EBMUD plans to use this
24 information to comment on improvement options proposed by CA DWR (EBMUD, 2009b).
25
26 2.4.2. Hydropower Generation
27 While extreme weather events may cause more intense precipitation and flooding, total
28 annual precipitation may decrease. Decreased annual precipitation would not only affect the
29 ability to meet water needs but also would affect hydropower generation. To model the potential
30 range of effects, EBMUDSEVI was used. EBMUDSEVI is a monthly model of the EBMUD water
31 supply system from the Mokelumne River reservoirs to the five terminal reservoirs in the service
32 area, all of which are modeled as one combined reservoir (Chan, 2010). Results suggested that
33 the projected changes in total precipitation may lead to a 10-30% decrease in hydropower
34 generation (Wallis et al., 2008).
35
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1 2.4.3. Water Supply
2 EBMUD had several ongoing activities related to climate change, but the first extensive,
3 quantitative analyses to assess the effects of climate change on its water supply system were
4 conducted for WSMP 2040. The main objective of WSMP 2040 was to identify and recommend
5 a portfolio of projects for meeting customers' dry-year water needs through 2040.2 The process
6 consisted of six steps: (1) identifying a list of projects for providing additional supply,
7 (2) screening the projects, (3) developing portfolios of projects that satisfy water needs through
8 2040, (4) screening 14 preliminary portfolios under historic hydrology with existing drought
9 planning sequence, (5) modeling five of these portfolios under the effects of projected climate
10 change, and (6) making a final portfolio selection. Projects included changes in rationing,
11 conservation, water reuse, surface water transfers, groundwater banking/exchange, desalination,
12 and enlargement of reservoir(s) (EBMUD, 2009b). Several uncertainties were identified
13 regarding the proposed projects, including institutional and legal challenges, undefined timelines
14 for project completion, and climate change. To reduce these uncertainties, a reliable portfolio
15 was defined as being (1) robust with respect to an uncertain future, (2) composed of projects that
16 can be pursued simultaneously, and (3) flexible and diverse (EBMUD, 2009c). In order to
17 inform the selection of a reliable portfolio, a climate change analysis was conducted.
18 EBMUD reviewed 10 other water agencies in California to determine how each was
19 assessing its vulnerabilities to climate change (EBMUD, 2009a). Based on this information,
20 EBMUD considered five approaches for evaluating the effects of climate change on the water
21 supply system: (1) qualitative analysis, (2) perturbing historic hydrology based on perturbation
22 factors from existing studies, (3) hydrologic modeling based on existing climate-derived
23 hydrology by other studies, (4) hydrologic modeling using climate-derived temperature and
24 historic precipitation, and (5) sensitivity analyses using historic hydrology in a hydrologic model
25 (EBMUD, 2009b). A "bottom-up" approach using sensitivity analyses was selected based on a
26 recommendation by Miller and Yates (2006). A bottom-up approach consists of identifying the
27 factors that most affect the system's reliability and testing the system's sensitivity to and
28 performance under expected changes in those factors (EBMUD, 2009b).
29 EBMUD identified the three most significant factors that affect the water supply system's
30 reliability in meeting the projected 2040 dry-year water needs: (1) greater-than-expected
31 customer demand, (2) shift in the timing of spring runoff, and (3) decreased volume of
32 precipitation and runoff. EBMUD modeled three sets of scenarios based on these three factors
33 with potential changes in each factor based on the existing regional climate change studies to
2Existing supplies were estimated to be sufficient during normal and wet years.
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1 determine the effect of each factor on the performance of the existing system.3 Modeling
2 assumptions included using existing conservation and recycled water levels, existing drought
3 planning sequence, and a maximum of 25% rationing. The model was run from 1953 to 2002
4 according to each of the three scenarios (EBMUD, 2009a). Although climate change projections
5 from the IPCC, PIER/CCCC, and CA DWR reports have significant uncertainties, they provided
6 an approximate range of potential changes in climate and hydrology. From this range, EBMUD
7 selected and modeled those changes that are expected to affect the utility's ability to provide
8 sufficient water and meet regulatory obligations for downstream water flow and temperature
9 (e.g., increases in precipitation were not modeled).
10
11 2.4.3.1. Increased Demand
12 To test the effects of increased water demand, 2040 water demand estimates were
13 recalculated assuming a 4°C increase in air temperature, resulting in a 3.6% increase in demand.4
14 The higher demand estimate accounts for higher consumptive use for drinking and outdoor
15 watering due to higher temperatures alone. A 20% decrease in precipitation had relatively little
16 effect on demands compared to the temperature increase. Therefore, only the demand estimate
17 based on a temperature increase was run in the W-E model. Results showed an average decrease
18 in carryover storage of 3%, with a maximum decrease of 8%. Carryover storage is significant
19 for the EBMUD water supply system, because the reservoirs do not necessarily refill each year,
20 depending on drought conditions. The results also indicate that the extent of customer rationing
21 increased to a maximum of 5.6%, but the frequency with which rationing occurred did not
22 change. Flood control releases were not analyzed (EBMUD, 2009a).
23
24 2.4.3.2. Temporal Shift in Runoff
25 As a result of increasing temperatures, the volume of runoff between April and July
26 decreased by approximately 10% over the past century (Wallis et al., 2008). The sensitivity of
27 the water supply system to reductions in spring runoff and increased winter runoff was modeled
28 for 2°C, 3°C, and 4°C increases in temperature. The analysis estimated the decrease in the
29 volume of runoff from April through June and assumed an increase in the November to March
30 runoff by the same volume (EBMUD, 2009a). With 2°C, 3°C, and 4°C temperature increases,
31 estimated reductions in April through June runoff were 19%, 28%, and 38%, respectively.
32 Carryover storage decreased by an average of 2.5-6% and a maximum of 10-16%. Customer
3The 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 of this
chapter).
4The 4°C change is based on projected increases from 1980 to 2040 or 2.15°C from 2005 to 2040.
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1 rationing was estimated to increase by a maximum of 7%. Flood control releases increased in
2 60% of the years between November and May by an average of 66-89%. Between April and
3 July, flood control releases decreased in 35% of the years by 40-80% (EBMUD, 2009a).
4 The shifts in the timing of runoff did not have a significant impact on EBMUD's ability
5 to meet water demand because EBMUD's total reservoir storage is larger that the total annual
6 average runoff (EBMUD, 2009a). This provides the ability to reconfigure system operations for
7 fewer flood control releases (Wallis et al., 2008). However, when considered in combination
8 with the need to adjust flood releases from the Camanche Reservoir to accommodate extreme
9 precipitation events as predicted above, it suggests that there will be a more delicate balance
10 between flood control and capturing the projected temporal shift in spring runoff.
11
12 2.4.3.3. Decrease in Annual Precipitation
13 The effect of reduced precipitation was assessed by assuming that reductions of 10% and
14 20% in the volume of annual precipitation directly correspond to 10% and 20% decreases in
15 runoff. Both scenarios were run in the W-E model, with the most significant effects observed
16 among all the scenarios. For the 10% and 20% reductions in precipitation, the average decreases
17 in carryover storage were 12% and 24%, respectively, and the maximum decreases were 47%
18 and 76%, respectively. The magnitude of customer rationing increased on average by 3.8% and
19 6.4% for the 10% and 20% decreases in precipitation, respectively. The frequency of rationing
20 increased from a baseline of 36% to 44% and 52%, respectively, for the 10% and 20% decreases
21 in precipitation. Average annual flood releases decreased by 43% and 74% for the 10% and 20%
22 decreases in precipitation, respectively (EBMUD, 2009a).
23 The magnitude of these results may be evaluated relative to the worst drought on record,
24 which occurred in 1976 and 1977 and resulted in a 75% decrease in average runoff and a
25 70% reduction in total reservoir capacity (EBMUD, 2009a). A limitation of these sensitivity
26 analyses is that the change in each vulnerability factor was modeled individually, and the
27 synergistic effect of the simultaneous change in all three factors at same time was not considered
28 (EBMUD, 2009b). A final scenario with all three factors would have provided insight into the
29 worst-case scenario.
30
31 2.4.4. Water Quality
32 EBMUD used the Watershed Analysis Risk Management Framework (WARMF) model
33 to assess the effect of increasing air temperatures on water temperatures. The WARMF model
34 had been developed by the Upper Mokelumne River Watershed Authority for a different study in
35 which EBMUD participated. This analysis was completed to determine the effect of climate
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1 change on EBMUD's continued ability to meet its cold-water obligations to the downstream fish
2 hatchery (EBMUD, 2009a).
3 Six water years were modeled, including two dry years, three below-normal years, and
4 one above-normal year. Each year was modeled for increases of 2°C, 3°C, and 4°C. Overall
5 scenarios, average annual water temperatures increased by 0.3-3.5°C relative to baseline
6 temperatures. In general, the effect of increasing temperatures was found to depend on the type
7 of hydrologic year and the season. In the drier years and during summer months, streamflow is
8 lower, and air temperatures have a greater effect on water temperatures (EBMUD, 2009a).
9 EBMUD studies also identified other water quality effects from climate change,
10 including a greater potential for algae growth with higher water temperatures. In addition, with
11 increasing intensity and frequency of storm events, turbidity levels may increase in water supply
12 sources. Because the EBMUD drinking water treatment plants were designed for treating source
13 water that is low in turbidity, increases in turbidity may decrease the plants' daily output and
14 increase treatment costs (Wallis et al., 2008).
15
16 2.5. APPLICATION OF VULNERABILITY ASSESSMENT INFORMATION
17 Of the four case studies discussed in this report, EBMUD may have used the most
18 elaborate policy analysis as part of its WSMP 2040 initiative. Several key insights were
19 provided by the climate change analyses for the WSMP decision-making process. Although
20 EBMUD staff already knew before conducting these studies that diversification of water supply
21 sources was needed, the vulnerability studies provided further support for the recommended
22 adaptation measures.
23 The analyses showed a clear distinction between the effects of temporal shifts in
24 precipitation and a decrease in total annual precipitation. The temporal shifts could be managed
25 by adjusting system operations, while decreased precipitation would require additional sources of
26 water outside of the Mokelumne River Watershed. Before conducting these studies, EBMUD
27 believed that diversification of water supply sources was needed, and the climate change
28 vulnerability studies provided further support for the recommended adaptation measures.
29 The studies reaffirmed the need for diversifying water supply sources outside of the
30 watershed and selecting projects that can be adapted as climate change effects are observed. For
31 example, instead of only relying on enlarging existing reservoirs, EBMUD will pursue additional
32 surface water and groundwater sources. Plans will also be drawn up for regional desalination.
33 To meet the 2040 dry-year water needs, conservation, desalination, and the enlargement of
34 reservoirs in combination with some groundwater banking and exchange are needed. Pursuing
35 parallel tracks on alternative projects will allow for flexibility, not only with regulatory and
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1 logistical challenges, but also with adjusting to future refinements of climate change projections.
2 While water quality vulnerabilities were not directly addressed, the vulnerability analyses
3 revealed that the interaction of lower water levels in the reservoirs and increased air temperatures
4 are the causal factors; addressing water quantity will mediate water quality concerns. However,
5 this was not explicitly addressed.
6 To support continued climate change vulnerability assessments and adaptation activities,
7 EBMUD has identified two main resources that would support these efforts: (1) information on
8 the probabilities of specific projected changes in temperature and precipitation, and (2) a
9 common source for region-specific environmental data to assist in vulnerability analyses (Chan,
10 2010).
11
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1 3. NEW YORK CITY DEPARTMENT OF ENVIRONMENTAL PROTECTION
2 3.1. BACKGROUND
3 New York City's Department of Environmental Protection (DEP) is responsible for the
4 operation, protection, and maintenance of New York City's drinking water system (DEP, 2010a).
5 DEP supplies 1.1 billion gallons per day (gpd) of drinking water to 8.2 million residents of New
6 York City, and an additional 1 million people in nearby municipalities (DEP, 2008b). DEP
7 supplies approximately 85% of the water for Westchester County and 5-10% of the water needs
8 of Orange, Putnam, and Ulster Counties (Rosenzweig et al., 2007). Additionally, the system
9 provides legally mandated conservation releases to the Delaware River Basin (DEP, 2008b).
10 New York State experiences a humid continental climate but with dramatic variations
11 from that climate type due to latitude, general circulation patterns, and topography. Although the
12 region is located along the coast, the area is dominated by drier continental airflow from the
13 prevalent westerly winds. The state's climate is conditioned primarily by cold, dry air masses
14 from the northern continental interior, as well as warm, humid air masses from the south
15 conditioned by the Gulf of Mexico. A third, but relatively less important air mass is the
16 maritime influence of the North Atlantic Ocean, which can produce cool, cloudy, and damp
17 weather. Due to the prevailing winds, however, this maritime influence is secondary to the more
18 prevalent airflow from the continental interior (New York State Climate Office, 2010).
19 Average annual temperature is approximately 55°F in New York City but 10-15°F cooler
20 in the Catskills. The distribution of precipitation across New York State is influenced by
21 topography and proximity to the Great Lakes and Atlantic Ocean. Average annual precipitation
22 amounts can exceed 50 inches in the Catskills. In New York City, average annual precipitation
23 is 43-50 inches per year, depending on location within the city. Precipitation is evenly
24 distributed throughout the year, and there are no distinctly wet or dry seasons repeated on an
25 annual basis, although minimum precipitation tends to occur in the winter and maximum
26 precipitation in the summer (NYC Panel on Climate Change, 2009; New York State Climate
27 Office, 2010).
28 In the mountainous areas of New York State, such as the Catskills, average snowfalls
29 range from 70-90 inches, but topography and elevation produce great variation in snowfall over
30 even short distances in the state's interior. The bulk of wintertime precipitation in these areas
31 falls as snow. New York City, however, receives only some 25-35 inches of snow per year due
32 to the moderating influence of the Atlantic Ocean. Because of the temperature modulation of the
33 coastal zone, only about one-third of the winter season precipitation falls in storms that include
34 snow accumulation of at least 1 inch (New York State Climate Office, 2010).
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City Tunnel No. 3
City Tunnel No.
Figure 3. New York City Department of Environmental Protection (DEP)
system overview.
Source: DEP (2008a).
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1 Instrumental measurements indicate that annual mean temperature in New York City has
2 increased 2.5°F since 1900, although both warming and cooling periods occurred over this time.
3 Mean annual precipitation levels have increased only slightly since 1900, but interannual
4 variability in precipitation has increased (NYC Panel on Climate Change, 2009).
5
6 3.2. DESCRIPTION OF THE WATER SYSTEM
7 3.2.1. Water Supply System
8 New York City's surface water is supplied from a network of 19 reservoirs and
r\
9 three controlled lakes in a watershed that stretches nearly 2,000 mi and extends 125 mi north of
10 New York City (Figure 3). The watershed is divided into two geographically discrete regions—
11 the Croton Reservoir system, which is located north of the city and east of the Hudson River, and
12 the Catskill/Delaware Reservoir system, located in upstate New York, well north and west of the
13 city and the Hudson River. Additionally, less than 1% of New York City's water is obtained
14 from the Brooklyn-Queens Aquifer, located in southeastern Queens (DEP, 2008a).
15 The Catskill/Delaware reservoir systems provide approximately 90% of New York City's
16 water. The Catskill Water Supply System was completed in 1927, and the Delaware Water
9 _
17 Supply System in 1967. Together, these watersheds cover roughly 1,600 mi (U.S. EPA, 2009a).
18 Forests cover approximately 75% of the watersheds. An estimated 75% of the forested land area
19 is owned by more than 20,000 private landowners (Brunette and Germain, 2003).
20 In 1993, New York City began implementing watershed protection programs to reduce
21 the susceptibility of the surface water supply to a number of contaminants. In 1997, The U.S.
22 Environmental Protection Agency (EPA) partnered with the State of New York, the City of New
23 York, and some 80 watershed municipalities, environmental groups, and agricultural
24 organizations to forge the New York City Watershed Memorandum of Agreement (MO A). This
25 MOA set forth a set of conditions that the city had to meet for EPA to issue a 5-year Filtration
26 Avoidance Determination (FAD), which allows DEP to avoid filtering its Catskill/Delaware
27 drinking water by establishing a land acquisition program for source water protection, by setting
28 more stringent New York City watershed rules and regulations, and by implementing other
29 watershed protection strategies. EPA reissued New York City a 5-year FAD in 2002 and a
30 10-year FAD in 2007. These ongoing source water quality programs are monitored by the New
31 York State Department of Health and EPA. Projects include
32
33
34 • Land Acquisition—New York City buys property from willing sellers to buffer the
35 reservoirs and controlled lakes.
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1 • Land Management—DEP develops land management programs.
2 • Partnership Programs—DEP partners with many local organizations for source water
3 quality, for example, by improving septic systems.
4 • Wastewater Treatment Plant Upgrades—New York City funds improvements to
5 non-NYC-owned wastewater treatment plants for communities in the source watersheds.
6 • Stream Management Programs—DEP supports partnerships to stabilize streams in the
7 area.
8 • Watershed Agricultural Programs and Forestry Program—The Program works with
9 farms to help implement best management practices that reduce agricultural pollution and
10 protect water quality (DEP, 2008a).
11
12
13 Because of glacial clay deposits underlying stream channels and steep topography
14 surrounding the waterways, in the Catskill water system there are risks of high turbidity due to
15 intense precipitation events and associated runoff. Maintaining the FAD on the Catskill and
16 Delaware water supplies is a crucial element to future watershed plans. In order to meet
17 FAD-required standards, DEP has occasionally added alum to the waters entering Kensico
18 Reservoir to reduce turbidity.5 However, periodically the alum and associated sediment must be
19 dredged from the reservoirs (DEP, 2005).
20 The Croton Watershed system covers approximately 375 mi2 east of the Hudson River in
21 Westchester, Putnam, and Dutchess Counties and a small section of Connecticut. It includes
22 three upland reservoir systems and supplies approximately 10% of the city's freshwater supply.
23 The system began service in the mid-1800s and was completed prior to World War I
24 (Rosenzweig et al., 2007). Since the 1950s, the Croton Watershed has developed quickly with
25 the construction of 60 wastewater treatment plants, interstate highways, residential
26 developments, and impervious surfaces (New York Water, 2010).
27 On several occasions, the Croton Watershed has been contaminated as a result of
28 stormwater runoff. For example, DEP provides water to some 800,000 residents of Westchester
29 County. But 12 of the County's 45 municipalities lie within the boundaries of the Croton
30 Watershed, contributing to water supply contamination from lawn care chemicals, automobile
31 use, combined sewer system overflows, and other human factors, as well as reduced infiltration
32 of precipitation that flows through urban drainage infrastructure. In 1993, EPA determined that
33 the Croton system failed to meet the requirements of the Surface Water Treatment Rule, and
5Alum serves as a coagulant, precipitating suspended solids from raw water, reducing objectionable color and
turbidity.
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1 Croton system raw water would need to be filtered and disinfected. Repeated violations of
2 turbidity and disinfectant by-product rules under the 1996 Safe Drinking Water Act Amendments
3 have caused DEP to periodically remove the Croton system from service (Water-Technology.net,
4 2010; DEP, 201 Ob). After several delays and consent orders resulting in fines, the first phase of
5 construction of the Croton raw-water treatment plant began in 2006 and is expected to be
6 operational by 2012. Treatment will include a pretreatment stage, mixing and coagulation,
7 flocculation, chemical balancing, stacked dissolved air floatation, and ultraviolet and chlorine
8 treatment. The filtration plant is expected to improve water quality by reducing turbidity,
9 decreasing the risk of microbiological contamination, and reducing the levels of disinfection
10 by-products (DEP, 2008a). Communities around the Croton Watershed were also signatories of
11 the 1997 MO A aimed at improving watershed protection. They are participating in land
12 acquisition and other raw water quality projects, as discussed above (DEP, 2008a).
13
14 3.2.2. Wastewater System
15 DEP is also responsible for the operation, protection, and maintenance of New York
16 City's wastewater system. The wastewater network includes over 6,000 mi of wastewater pipes,
17 135,000 sewer catch basins, 494 permitted outfalls, 93 wastewater pumping stations, and
18 14 wastewater treatment plants spread across the city's five boroughs (Rosenzweig et al., 2007).
19 On average, the system treats 1.4 billion gpd of wastewater and has the capacity to treat
20 dry-weather flows of 1.8 billion gpd (DEP, 2006).
21 New York City's wastewater undergoes five major processes: preliminary treatment,
22 primary treatment, secondary treatment, disinfection, and sludge treatment. New York has
23 approximately 60% combined sewers, making combined sewer overflows (CSOs) during intense
24 precipitation events a continuing problem for DEP (DEP, 2008b). Violations of New York
25 City's 1988 State Pollutant Discharge Elimination System permit led to a 1992 consent order
26 between New York State's Department of Environmental Conservation and DEP, requiring a
27 CSO abatement program. A 2004 consent order with more detailed guidance includes
28 requirements for over 30 citywide projects, such as sewer separation, flushing tunnels, off-line
29 retention tanks, and vortex concentrators to improve the efficiency of the wastewater system
30 (NYSDEC, 2010).
31
32 3.3. CLIMATE CHANGE PROJECTIONS AND RISKS
33 DEP expects temperatures in New York City and its watersheds to increase by 1.5-3°F
34 by the 2020s, 3-5°F by the 2050s, and 4-7.5°F by the 2080s (Table 2). Natural precipitation
35 variability in this area is large. While most climate model projections indicate small increases in
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1
2
3
4
5
6
7
8
9
10
11
12
precipitation, some models 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 approximately a 0-5% increase by
the 2020s, a 0-10% increase by the 2050s, and a 5-10% increase by the 2080s. Most models
indicate precipitation increases for the winter months and slight decreases during September and
October. Furthermore, as temperatures increase, it is expected that more precipitation will 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, p. 17, 20).
13 New York City has taken a proactive approach to climate change. In 2001, the city
14 joined the Local Governments for Sustainability's Cities for Climate Protection campaign. In
15 2004, DEP created a climate change task force to assess the potential impacts of climate change
16 on the city's water infrastructure. The task force is composed of representatives from a variety
17 of DEP's offices and initially included participants from Columbia University's Center for
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1 Climate Systems Research, the National Aeronautics and Space Administration's Goddard
2 Institute for Space Studies, HydroQual Environmental Engineers and Scientists, P.C., the New
3 York City Office of Environmental Coordination, the Mayor's Office of Long-term Planning and
4 Sustainability, and the New York City Law Department. The task force created an action plan,
5 which includes the following tasks (DEP, 2008b):
6
7
8 • Work with climate scientists to improve regional climate change projections
9 • Enhance DEP's understanding of the potential impacts of climate change on DEP's
10 operations
11 • Determine and implement appropriate adaptations to DEP's water systems
12 • Inventory and manage greenhouse gas emissions
13 • Improve communications and tracking mechanisms
14
15
16 A sustainability plan for New York City, PlaNYC, was unveiled on Earth Day, in 2007.
17 The plan outlines a 25-year vision for the city, focusing on maintaining and improving the city's
18 infrastructure focusing on land, water, transportation, energy, air, and climate change. PlaNYC
19 has set an ambitious target to reduce the city's greenhouse gas emissions by 30%. New York
20 City's plan for climate change adaptation includes (1) creating an intergovernmental task force to
21 protect the city's infrastructure, (2) working with vulnerable neighborhoods to develop
22 site-specific plans, and (3) launching a citywide strategic planning process (PlaNYC, 2007a).
23 To respond to climate change in New York City and to meet the goals established in
24 PlaNYC, the New York City Panel on Climate Change (NPCC) was created in 2008. This panel
25 is composed of climate change scientists, as well as legal, insurance, and risk management
26 experts. With funding from the Rockefeller Foundation, NPCC has been charged with serving as
27 the technical advisory body for the Mayor and the New York City Climate Change Adaptation
28 Task Force. This organization has provided the Climate Change Adaptation Task Force with the
29 most comprehensive set of climate data that has been produced for New York City (NYC Panel
30 on Climate Change, 2009). Several of the experts engaged to assist DEP in 2004 were also
31 engaged to assist NPCC in citywide planning efforts. DEP continues to pursue complementary
32 climate change research because it is concerned with climate change in upstate New York (where
33 the Catskill and Delaware watersheds are located) as well as in the city itself.
34
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1 3.4. CLIMATE CHANGE VULNERABILITY ASSESSMENTS
2 DEP's vulnerability work is based on three core questions of interest to DEP, including
3 the potential effects of climate change on (1) total water supply, (2) turbidity, and
4 (3) eutrophication (Barsugli et al., 2009). DEP worked with researchers from Columbia
5 University's Center for Climate Systems Research to design its Climate Impact Assessment
6 project (Major et al., 2007). The goal of this integrated modeling project is to estimate the effect
7 of future climate change on the quantity and quality of New York City's water supply. The
8 project will combine the use of climate change projections, DEP water quality and water supply
9 models, and analytical measures of system performance to advance DEP's understanding of the
10 potential impacts of climate change on the water supply system.
11 The project is planned in two phases. Phase I, now completed under contract with
12 Columbia University and the City University of New York (CUNY), is aimed to provide a
13 first-cut evaluation of the effects of climate change on water quantity and quality in selected
14 portions of the water system, using the existing modeling system and data available from
15 three general circulation models (GCMs). Phase II, now in process continued support from
16 CUNY, has similar goals as Phase I but with upgrades to both models and data sets applied to the
17 entire water supply system, including a greater variety of GCM data and an evaluation and
18 application of differing downscaling methods. The Phase I effort used the Intergovernmental
19 Panel on Climate Change (IPCC) Third Assessment Report (DEP, 2008b; McCarthy et al.,
20 2001), but current efforts have upgraded models and data that were used in the IPCC
21 Fourth Assessment Report (Parry et al., 2007).
22 A climate change scenario framework was developed for the New York City water
23 supply system using high-temporal-resolution data from the Program for Climate Model
24 Diagnosis and Intercomparison (PCMDI) Web site maintained by the Lawrence Livermore
25 National Laboratory in Berkeley, California (Maurer et al., 2007). Data for Phase I were
26 extracted from the single grid box at the center of the watershed region. Baseline data for
27 1981-2000 came from "hindcast" model runs, while data for 2046-2065 and 2081-2100 came
28 from three GCMs (the Goddard Institute for Space Studies [GISS] Model, the Max Planck
29 Institute [MPI] ECHAM5, and the National Center for Atmospheric Research [NCAR] CCSM3)
30 coupled with three scenarios from the IPCC Special Report on Emissions Scenarios: A1B, A2,
31 and B1. The data included mean temperature, maximum temperature, minimum temperature,
32 precipitation, sea level pressure, zonal wind, meridional wind, solar radiation, longwave
33 radiation, and dewpoint temperature.
34 For Phase I, each scenario was used to calculate delta change coefficients representing
35 mean monthly change in air temperature and precipitation between control and future prediction
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1 periods. Monthly delta change factors were applied additively for air temperature and as a ratio
2 for precipitation to historical meteorological period data, generating a future prediction time
3 series. The possibility of applying the delta change method to the wind and solar radiation data
4 needed for the reservoir models was also investigated.
5 For Phase II, GCM selection included the entire CMIP3 multimodel data set, the A2,
6 A1B, and Bl emissions scenarios, and seven meteorological variables (precipitation, maximum,
7 minimum and average temperatures, zonal and meridional winds, and solar radiation). Data
8 from all the GCMs were regridded to 2.5° corresponding to the Eastern North America region
9 using bilinear interpolation and the NCAR Command Language (NCL: www.ncl.ucar.edu). The
10 various levels of data processing involved necessitated some data to be eliminated from the study
11 dependent on the number of models that contain a given meteorological parameter, the number
12 of runs archived for each GCM, and whether data existed for all points necessary in the
13 regridding process. GCM hindcasts were compared to historical data sets at four spatial scales:
14 Eastern North America, the nine grid points surrounding West of Hudson watersheds, the four
15 grid points surrounding New York City, and the single grid point closest to the centroid of New
16 York City watersheds. To develop a skill ranking and probability distribution function for each
17 meteorological variable, spatial scale, seasons (December to February, March to May, June to
18 August, and September to November), and GCM, the fidelity of hindcast values to observed
19 historical data, was calculated.
20 The system of models that will be used for the integrated modeling project include the
21 General Watershed Loading Function (GWLF) and Soil Water Assessment Tool (SWAT)
22 watershed models, a one-dimensional reservoir eutrophication model, a two-dimensional
23 reservoir turbidity transport model (CEQUAL-W2), and the OASIS system operations model for
24 the entire water supply. These models taken together with the existing and in-progress climate
25 scenarios make the proposed integrated assessment possible.
26 As the project progresses, further model enhancements and integration will be
27 implemented. For the GWLF watershed model, this includes improvements to the following
28 model elements: hydrologic balance, sediment and nutrient generation and transport, ecosystem
29 effects, and land use. For the reservoir models, this includes additional upgrades and calibration
30 and development of response function models keyed on system performance measures. For the
31 integrated system, this includes enhanced coupling of the watershed and reservoir models to
32 OASIS. And for model inputs, this includes advanced delta change with historical data
33 morphing, statistical downscaling, and regional climate model (RCM) simulations.
34 A number of performance measures related to water system quantity and quality will be
35 developed and used to estimate climate change effects, including total water quantity,
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1 probabilities of refill, probabilities of drawdown, key point turbidity levels, frequency of alum
2 use, reservoir phosphorus and chlorophyll concentrations, and restrictions in water use due to
3 eutrophi cation. DEP expects the results of this project to provide the basis for recommendations
4 about system operation now and in the future, and, in later phases, recommendations about
5 required infrastructure changes and improvements.
6 In 2009, the NPCC published its first report, Climate Risk Information. This report
7 provides climate change projections for New York City as a whole (not just DEP) and identifies
8 potential risks to the City's critical infrastructure. The projects presented in the model were
9 compiled using model-based probability functions. The NPCC used IPCC methods to calculate
10 probabilities for temperature, precipitation, and sea level rise from global climate models
11 simulations based on three greenhouse gas emission scenarios (A1B, A2, Bl). The NPCC used
12 16 GCMs to generate possible changes in temperature and precipitation. It used only
13 seven GCMs for sea level rise, as sea level rise is not a direct output of most GCMs. The
14 generated sea level rise values for the New York City region include both global and local
15 components.
16 According to the NPCC report, changes in mean climate and climate extremes may affect
17 many aspects of New York City's water infrastructure. The potential wastewater and drinking
18 water impacts of the projected air temperature change include decreased water quality due to
19 biological and chemical impacts; increased water demand due to a longer growing season;
20 decreased snowpack, which may reduce inflows to reservoirs during the spring thawing season;
21 changes in the ecology of streams due to higher stream temperature, which may limit the amount
22 of water that can be extracted; and increased water demand. The biological and chemical
23 reactions in wastewater treatment plants could also be disrupted at higher temperatures (DEP,
24 2008b).
25 Impacts related to the potential changes in precipitation include increased turbidity,
26 increased probability of sewer flooding, increased nutrient loads, eutrophi cation, taste and odor
27 problems, increased loading of pathogenic bacteria and parasites in reservoirs, increased CSO
28 events, decreased average reservoir storage, and increased strain on upstate reservoirs.
29 The impacts of potential sea level rise for city water resources include an increase of the
30 salt front up the Hudson River (NASA, 1999), increased probability of seawater entering sewers,
31 reduced ability of wastewater treatment plants to discharge treated water by gravity alone,
32 increased risk of CSO events, and increased flood risk for low-elevation infrastructure and
33 wastewater treatment plants (NYC Panel on Climate Change, 2009; DEP, 2008b).
34
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1 3.5. APPLICATION OF VULNERABILITY ASSESSMENT INFORMATION
2 Like East Bay Municipal Utility District, DEP also conducted a suite of model studies to
3 understand vulnerability and has made decisions to reduce the vulnerability of its systems to
4 climate change. However, this may be a case where policy and analysis, although informing
5 each other, are also proceeding in parallel. New York City's climate change work has led to
6 increased incorporation of climate change in strategic planning, has altered operations and
7 maintenance practices, and has changed future infrastructure planning and design. Many of
8 these changes are not a direct result of any of the New York City vulnerability assessments.
9 Rather, they are part of a larger effort to improve the resiliency and redundancy of water
10 infrastructure in the face of existing vulnerabilities exacerbated by climate change. These
11 decisions largely focus on so-called no regret adaptations, or changes to the water supply system
12 that make sense regardless of whether climate changes. Some of these policy choices have been
13 forced by regulatory mandates, such as the development of a filtration plant for the Croton
14 Watershed, but others have significant benefits system-wide, such as reducing leakage from
15 aging supply infrastructure.
16 PlaNYC and DEP's Climate Change Task Force have identified a number of initiatives
17 that aim to efficiently and effectively upgrade the city's drinking and wastewater systems in the
18 face of a changing climate. Proposed initiatives are discussed in detail below.
19
20 3.5.1. Decreasing Turbidity
21 Turbidity is a significant drinking water concern in the Catskill and Delaware water
22 systems. DEP has addressed this issue historically by adding alum as an "end-of-pipe" solution
23 and engaging in source water protection measures. Projected increases in intense precipitation
24 events under climate change will most likely increase the turbidity of watersheds beyond historic
25 levels. New York City is continuing its historic programs to address this issue. In the future,
26 DEP will address potential turbidity challenges in the Catskill and Delaware water systems by
27 relying more heavily on the soon-to-be-filtered Croton system, a proposed interconnection
28 between the Catskill and Delaware Aqueducts, and operational modifications un how DEP uses
29 the Delaware and Catskill water systems during heavy precipitation or turbidity events.
30
31 3.5.2. Minimizing Flooding
32 To minimize flooding in New York City during the predicted increased severe weather
33 events, the Climate Change Task Force proposed more frequent cleaning of sewers and
34 maintaining catch basins in flood-prone areas. Additionally, the task force promoted green roofs
35 and the reuse of stormwater for "ecologically productive purposes." Green infrastructure has
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1 become a significant component of DEP's proposed policies, especially for stormwater
2 management (PlaNYC, 2008).
3 For example, New York City is planning to expand the Staten Island Bluebell program,
4 which was created as a natural system to prevent flooding and septic tank failure. It functions by
5 diverting water from wastewater treatment to natural systems. Nearly 36% of State Island's
6 precipitation is diverted to a 10,000-acre Bluebell. The Bluebell program has saved the city an
7 estimated $80 million in infrastructure development (Rosenzweig et al., 2007). As severe
8 weather events increase, the Bluebell and further expansions of Ihe concepl will acl as a nalural
9 buffer, reducing pressure on Ihe waslewaler system and reducing flooding issues and CSOs
10 (PlaNYC, 2008).
11
12 3.5.3. Minimizing Supply and Demand Imbalances
13 Higher temperatures increase peak water demand. Wilhin New York Cily, annual
14 average demand is approximately 1,069 mgd. During heal waves, demand can increase lo over
15 2,000 mgd. To minimize supply and demand imbalances, Ihe Climate Change Task Force has
16 slressed Ihe importance of slruclural improvemenls, such as reducing water pressure problems
17 and leakage. Additionally, small-scale conservation efforts can reduce water demand (DEP,
18 2008b).
19 New York Cily has successfully reduced water demand since 1985 wilh a variely of
20 conservation efforts, including education, metering, water-use regulation, leak detection,
21 installation of magnetic-locking hydranls, and rebate programs. These conservation efforts
22 reduced water consumption from 195 gpd per capila in 1991 lo 167 gpd per capila in 1998, wilh
23 coincidenl substantial cosl savings for bolh DEP and ils customers (U.S. EPA, 2002). Reducing
24 water demand also limils Ihe amounl of water entering Ihe waslewaler system and, Ihus, slress on
25 Ihe system. Wilh Ihe above conservation measures, Ihe volume of generated waslewaler
26 decreased by 200 mgd belween 1996 and 2006 (DEP, 2006).
27 Additionally, lo ensure sufficienl water quantity even in Ihe face of higher temperatures,
28 DEP is evaluating new water sources Ihroughoul New York Cily and upslream watersheds.
29 These include groundwaler sources and new infraslruclure, including potentially increasing the
30 capacity of Ihe Calskill Aqueduct
31
32 3.5.4. Combaling Combined Sewer Overflows
33 To combal CSOs caused by increased precipitation and intense precipitation evenls, DEP
34 has begun plans lo upgrade waslewaler Irealmenl capacity, conslrucl additional holding tanks lo
35 increase wel-wealher holding capacily, and optimize sewer infraslruclure lo limil releases.
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1 Additionally, New York City is planning to convert some of the combined sewer systems into
2 high-level sewer systems,6 which divert a large percentage of the stormwater directly to
3 waterways rather than into treatment plants. This not only decreases the likelihood of CSO
4 events but additionally reduces costs by avoiding unnecessary water treatment. The Climate
5 Change Task Force has also proposed increasing pipe size to increase flow in areas where this is
6 possible (PlaNYC, 2008). In mid-2010, DEP will release an adaptive management strategy for
7 reducing CSOs, using green infrastructure, grey infrastructure, system optimization, and water
8 conservation.
9
10 3.5.5. Adapting to Flood Risk
11 DEP is also considering converting water storage reservoirs to be used for both water
12 supply and flood control (DEP, 2005). To prevent critical assets from being disabled during
13 flood events, the DEP Climate Change Task Force has proposed moving key assets above
14 projected flood heights, installing watertight doors around crucial equipment, switching to
15 submersible pumps, and creating protective barriers around important assets, such as sea walls,
16 dunes, or tidal gates (DEP, 2008b).
17 DEP has decided to institute a snowpack-based reservoir management program to
18 provide enhanced flood attenuation downstream. Under this program, Schoharie Reservoir
19 would be sustained below full capacity during the winter months when sufficient snowpack is
20 present in its watershed such that associated runoff produced by spring snowmelt could refill the
21 Reservoir to full storage capacity. The capture of inflows associated with spring storm events
22 and snowmelt runoff in the Reservoir would provide additional attenuation in downstream
23 sections. The temporary reservoir level strived for during the snowpack-based reservoir
24 management period would be regularly adjusted based on snow water equivalent (SWE)
25 estimates of the watershed's regularly monitored snowpack. As the name implies, SWE is the
26 water depth equivalent of a given depth of snow and is dependent upon such factors as the
27 snowpack's water content and density. (Source:
28 http://www.nyc. gov/html/dep/pdf/gilboa/gilboa_proj _desc.pdf).
29
6High-level storm sewers alleviate pressure on the combined sewer system by capturing some 50% of 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 only cost-effective near the water's edge.
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1 4. SEATTLE PUBLIC UTILITIES
2 4.1. BACKGROUND
3 Seattle Public Utilities (SPU) was formed in 1997 as a combination of the Drainage and
4 Wastewater Utility, Solid Waste Utility, the former Seattle Water Department, and portions of
5 Seattle City Light and the Seattle Engineering Department. In this report, we focus on SPU
6 functions related to the provision of Seattle's drinking water supply and we touch briefly on
7 vulnerability assessments of changes in urban hydrology on SPU's drainage and wastewater
8 system.
9 SPU provides drinking water to a population of more than 1.35 million people in the City
10 of Seattle and suburban areas. SPU provides direct retail water service to about 630,000 people
11 mostly in the City of Seattle, parts of Shoreline, and small areas just south of the city limits.
12 SPU also sells water wholesale to 25 neighboring cities and water districts serving another
13 720,000 people. SPU supplied 45.1 billion gallons of drinking water in 2008 from two Cascade
14 Mountain watersheds supplemented with groundwater wells.
15 The Pacific Northwest climate is dominated by large spatial and temporal variations in
16 precipitation due to maritime influences and extreme topographical variation between the coast
17 and the Cascade Mountains. The low-lying valleys west of the Cascades, including SPU's
18 service area, are characterized by mild temperatures year round, wet winters, and dry summers.
19 Average annual precipitation for the Seattle area is about 37 inches, but in the mountains, that
20 total exceeds 100 inches. About 75% of Seattle area precipitation falls between October and
21 March (Miller and Yates, 2006). This means that the SPU water supply system is also managed
22 for floods. Typically, early winter precipitation fills reservoirs, which are allowed to spill in
23 anticipation of snowmelt combined with normally rainy springs, which refill reservoirs for the
24 dry summer months.
25 The Pacific Northwest is also strongly affected by the regional climate fluctuations
26 known as the El Nino Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO).
27 The relationship between ENSO, PDO, and the winter and spring climate of the region is highly
28 correlated, enabling predictions of Pacific Northwest precipitation, snowpack, and streamflow.
29 The University of Washington Climate Impacts Group (UW-CIG) develops annual climate
30 forecasts for regional resource managers, including annual projections of climate variations due
31 to ENSO and PDO. These forecasts help inform SPU managers about projected conditions over
32 the winter and spring months to enable more informed management of the competing objectives
33 of water supply and flood management (UW-CIG, 2010a).
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1 Observed changes in climate include the following: temperatures increased in the Pacific
2 Northwest by 1.5°F between 1920 and 2003 (Mote, 2003); annual precipitation increased by 14%
3 between 1930 and 1995 (Mote, 2003); April 1st snow-water equivalent has declined dramatically
4 at almost all Pacific Northwest sites (Mote et al., 2003, 2005, 2008; Hamlet et al., 2005); and
5 timing of peak runoff shifted earlier by 0-20 days between 1948 and 2002 (Stewart et al., 2004).
6
7 4.2. DESCRIPTION OF THE WATER SYSTEM
8 4.2.1. Water Supply System
9 SPU's water supply comes from three sources: the Cedar River Municipal Watershed, the
10 South Fork Tolt Watershed, and the Seattle Well Fields (Figure 4).
11 In 1895, Seattle residents voted to approve revenue bonds to construct the Cedar River
12 Municipal Watershed. The watershed, almost entirely owned by the City of Seattle, covers
13 90,638 acres and provides approximately 70% of the city's freshwater supply over the course of
14 the year. Rain and snowmelt are gathered and stored in two reservoirs created by the 1914
15 construction of the Masonry Dam—Chester Morse Lake and the Masonry Pool. As water leaves
16 these reservoirs, it powers the Cedar Falls hydroelectric power plant. Twelve miles downstream,
17 at the Landsburg diversion dam, on average, 22% of the river flow is screened to remove debris,
18 chlorinated for microbial control, and fluoridated for dental health. This water is then stored in
19 Lake Youngs, where it is ozonated for odor and taste improvements, ultraviolet disinfected to
20 disable chlorine-resistant microbes, chlorinated again, and supplemented with lime for
21 pH-adjusted corrosion control to minimize lead leaching in older plumbing systems.
22 The Cedar River Municipal Watershed is managed to provide an adequate water supply
23 (both for human use and instream conservation flows). The water supply system also provides
24 flood management and hydropower generation Morse Lake and the Masonry Pool hold, on
25 average, just enough water for one water cycle year. If too little water is released during winter,
26 there could be flooding in heavy rains or when the snowpack melts during the spring wet season,
27 so winter water levels are generally kept low. However, drought conditions in the spring could
28 prevent the reservoir from refilling to the level necessary to provide water during the dry summer
29 months. This implies a risk tradeoff that SPU water managers must address every year to meet
30 both flood management and water supply objectives (SPU, 2010b).
31 The South Fork Tolt Watershed is located on the western slope of the Cascade Range,
32 approximately 35 miles east of Seattle (Figure 5). The City of Seattle purchased water rights to
33 the South Fork Tolt from the Mountain Water Company in 1936, but no infrastructure existed for
34 the diversion, conveyance, or distribution of that water. The South Fork Tolt Dam was
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1 constructed in 1963, and in 1964, South Fork Tolt Reservoir began supplying water to north
2 Seattle and the
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Snohomish County
King County
Tolt Pipeline No. 1
South Fork Tolt Dam
Tolt Regulating Basin
and Powerhouse
'—Tolt Treatment Facility
Seattle
Well Fields
South Fork Toll River
Watershed
Cedar Falls
Powerhouse
Cedar River
Pipeline 1,2,3
Cedar River
Pipeline 4
Landsburg
Diversion
Masonry Dam
Overflow Dike
Chester Morse
Lake
Cedar River Watershed
'~^^^~
Pierce County
Seattle Regional Water Supply System
Seattle City Limits
Transmission Pipeline
Water Bodies
Municipal Watersheds
Current Area Served (2006)
Seattle Retail Service Area
Seattle Wholesale Customer
N
A
Figure 4. Seattle public utilities service area.
Source: SPU (2008).
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Figure 5. South Fork Tolt watershed.
Source: SPU (2008).
2 Eastside. As water leaves the reservoir, it powers the South Fork Tolt hydroelectric power plant.
3 After a land exchange with Weyerhaeuser Company in 1997, the City of Seattle owned 69% of
4 the 12,107-acre drainage area upstream of the South Fork Tolt Dam. Most of the remaining land
5 lies in the Mt. Baker-Snoqualmie National Forest. The South Fork Tolt Reservoir provides
6 approximately 30% of the city's freshwater supply (SPU, 2008, 2010c). The reservoir is also
7 operated to manage flood flows and maintain instream flows.
8 SPU's Tolt Treatment Facility, the city's first filtration and ozonation facility, began
9 operation in 2000. It provides 120 million gallons per day (mgd) of finished water to customers
10 in Seattle and suburban cities. While the facility has historically provided very high-quality
11 water, requiring only minimal treatment, it was designed to allow long-range conformity with
12 anticipated regulations, to increase system yield, and to permit continuous supply of Tolt water
13 though periods of high turbidity (SPU, 2010d). Like the Cedar River water supply, the Tolt
14 supply provides fluoridation, chlorination, and adjustment of pH and alkalinity for corrosion
15 control (SPU, 2006b).
16 In 1987, the first groundwater source was added to the system when two wells in the
17 Highline Well Field began operation. A third well was added in 1990. These wells supply less
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1 than 1% of SPU's water from an underground aquifer to supplement summer demands when
2 necessary. The well field can be pumped for 4 months and becomes available in July (WA DOE,
3 2001).
4 Water demand for the SPU system peaked in the 1980s at approximately 170 mgd. A
5 severe drought and mandatory water restrictions in 1992 caused demand to decrease.
6 Subsequently, higher water rates, plumbing code revisions in 1993, conservation efforts, and
7 improved systems operations caused demand to level out around 150 mgd. The economic
8 slowdown in 2000 and continued conservation efforts further reduced demand to approximately
9 130 mgd. This 24% decrease in demand coincided with a 17% increase in the population of
10 SPU's service area since 1990 (SPU, 2006b). This equates to a 27% decrease in water
11 consumption per capita from 145 gallons per day (gpd) per capita to 105 gpd per capita (SPU,
12 2010a).
13
14 4.2.2. Wastewater System
15 SPU also conveys wastewater to King County's Wastewater Treatment Division,
16 including associated infrastructure. This drainage infrastructure is partly a combined sewer
17 system, which means that SPU must addresses the City of Seattle's stormwater quality and
18 flooding issues, but often in conjunction with King County Department of Natural Resources and
19 Parks. Because the relative responsibilities of King County and SPU overlap to some degree,
20 this case study does not delve deeply into this aspect of the SPU system. It is worth noting,
21 however, that both SPU and King County own conveyance infrastructure within the city, and that
22 combined sewer overflow events are a problem for both entities. SPU has explored the
23 implications of climate change on its stormwater infrastructure and operations. In addition, SPU
24 is pursuing and evaluating adaptation options, engaging in research, and participating in
25 collaborative networks to address stormwater issues—effectively replicating their experience
26 with water supply, but for drainage and wastewater issues.
27
28 4.3. CLIMATE CHANGE PROJECTIONS AND RISKS
29 SPU expects climate in the Seattle area to change in several ways. Global climate models
30 (GCMs) project that temperatures will warm at 0.5°F/decade, nearly three times the rate
31 experienced over the 20* century, and the majority of models indicate small changes in
32 precipitation compared with 20th century observed interannual and decadal variability. Most
33 models, however, indicate increased winter precipitation and decreased summer precipitation.
34 Potential impacts of these changes include decreased mountain snowpack, higher winter and
35 lower spring streamflows, increased sea-surface temperatures, rising sea-levels, and increased
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1 winter flooding in the future (UW-CIG, 2010c; City of Seattle, 2006). Table 3 provides a
2 summary of temperature and precipitation projections, including average changes in Pacific
3 Northwest climate from 20 climate models7 and two greenhouse gas emissions scenarios8 (Bl
4 and A1B).9 (UW-CIG, 201 Oc).
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
5 A series of bad droughts in 1987, 1992, and 1997-1998 increased the sensitivity of SPU
6 managers to the effects of climate on their water supply. A very dry summer in 1987 caused
7 significant declines in raw-water supply quality and forced use curtailments, reduced instream
8 flows for fish, and necessitated the installation of an emergency pumping station to access low
9 water in Chester Morse Lake. In response, the city developed a Water Shortage Contingency
10 Plan (updated in SPU, 2006a) and a state-of-the-art reservoir management and streamflow
11 forecasting model for use in real-time water management and long-range planning. The 1992
http://cses.washington.edu/cig/fjpt/climatemodels08.shtml#models
8http://cses.washington.edu/cig/fpt/climatemodels08.shtml#ghgscenarios
9A11 changes are benchmarked to average temperature and precipitation for 1970-1999. Model values are weighted
to produce the "average." http://cses.washington.edu/cig/fpt/climatemodels08.shtml#rea
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1 water shortage was caused by following standard flood control rules after a below-normal winter
2 snowpack. When the spring season also produced below-normal precipitation, SPU's mountain
3 reservoir levels did not recover, and mandatory water restrictions were in place by mid-May.
4 Throughout the summer, raw-water quality declined, leading to a decision to invest in an
5 ozone-purification plant. SPU also implemented dynamic flood-control rules, which, in
6 conjunction with enhanced real-time snow, weather, and streamflow monitoring networks,
7 allowed SPU to successfully implement its new reservoir management approach. Finally, in
8 1997, new research on ENSO effects on the Pacific Northwest was incorporated into SPU's
9 reservoir management decisions. In anticipation of lower-than-normal snowpack followed by a
10 hot, dry summer, SPU allowed its mountain reservoirs to fill higher than normal and reduced its
11 operational use of water. These proactive decisions allowed the 1997-1998 drought to pass
12 without the public experiencing any water shortage or restrictions (UW-CIG, 201 Ob). Another
13 record low snowpack in 2005 threatened water shortages and use restrictions, but, again, careful
14 water management and late spring rains allowed SPU to successfully meet all water supply and
15 instream flow requirements without restrictions.
16 SPU's predecessor agencies were involved with climate change as far back as the 1980s
17 when they helped to develop the American Society of Civil Engineers' policy on global climate
18 change. That was followed by informal tracking of the climate variability and change issues by
19 SPU staff, until SPU formally integrated ENSO into its 1997-1998 reservoir management
20 decisions. In 2002, SPU contracted with UW-CIG to study the potential impacts of climate
21 change and to develop methods for how SPU could incorporate future climate change into its
22 water supply planning (SPU, 2006b). While a final report was never completed, the impacts on
23 water supply projected in the study were reported and incorporated into SPU's 2007 Water
24 System Plan. In a subsequent project, SPU began a new collaboration with UW-CIG to
25 investigate climate change in partnership with the Cascade Water Alliance, Washington State
26 Department of Ecology, and King County Department of Natural Resources and Parks as
27 described below (RWSP, 2010).
28 Participating agencies formed a Climate Change Technical Committee in spring 2006,
29 which was proposed in October 2005 by a collaborative planning process for water resource
30 management planning; the committee included SPU, along with a number of other city, county,
31 state, and tribal government officials managing water resources in the region. The committee
32 met 17 times from March 2006 through December 2007, and drafted a charter in April 2006
33 containing the following goals:
34
35
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1 • Identify the basic building blocks of our understanding of climate change;
2 • Identify what is known about climate change in the Puget Sound region and its potential
3 impacts;
4 • Identify where more information would be useful;
5 • Communicate what is known to other committees in this process; and
6 • Document the committee's findings (Palmer, 2007).
7
8
9 Ten technical reports authored by a research team from the University of Washington
10 were reviewed by the committee prior to public release. Information from this work was used by
11 SPU to assess impacts to water supply and demand, which is described below (Section 4.4).
12 SPU also joined several other major utilities to form the Water Utility Climate Alliance
13 (WUCA) in early 2007. WUCA commissioned two climate change white papers; one of which
14 was managed by SPU. The first white paper outlines potential improvements to scientific
15 models for projecting the impacts of climate change at spatial and temporal scales relevant to
16 utilities (Barsugli et al., 2009). The second white paper outlines decision-making approaches to
17 address climate change in water resource planning and management in the face of uncertainty
18 about future climate conditions (Means et al., 2010). In addition to WUCA, SPU is involved in
19 several other collaborative efforts to enhance the capacity of the water sector to identify and
20 prepare for the impacts of climate change. A staff member from SPU is cochairing U.S.
21 Environmental Protection Agency's (EPA's) Climate Ready Water Utilities Working Group,
22 which is developing recommendations on how EPA can support a "climate ready" water sector.
23 SPU is also a member of the Water Research Foundation's Climate Change Strategic Initiative
24 Expert Panel, which is assisting the Foundation in developing a multiyear climate change
25 research agenda for the drinking water sector, and is part of a similar effort lead by the Water
26 Environment Research Foundation to develop climate research for the clean water sector.
27 SPU operates in a political and managerial environment that supports engagement on
28 climate change adaptation. Seattle took early leadership roles in climate change on both the
29 mitigation and adaptation front. On February 16, 2005, for example, Seattle Mayor Greg Nickels
30 launched the U.S. Conference of Mayors Climate Protection Agreement. Mayor Nickels made
31 climate protection a keystone issue of his administration, creating the City of Seattle's
32 Environmental Action Agenda in 2005, including the Seattle Climate Protection Initiative and
33 the Seattle Climate Action Plan. The need to adapt to changes in water supply was highlighted
34 in the Seattle Climate Action Plan (City of Seattle, 2006). According to the Seattle Climate
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1 Action Plan, "It is vital that the City—and all levels of government—plan and prepare for the
2 climate change that is inevitable. Because Seattle's water and hydroelectricity are so dependent
3 on the hydrology cycle in the Cascade Mountains, the City has focused its planning and
4 adaptation analysis work there." By the time this was written in 2006, SPU had already begun
5 looking at climate change in earnest.
6
7 4.4. VULNERABILITY ASSESSMENT
8 SPU has commissioned or conducted a series of increasingly sophisticated analyses over
9 the course of many years to examine the vulnerability of their water supply and stormwater
10 infrastructure and operations to climate change. The analyses have benefitted from the expertise
11 of UW climate scientists and personnel at National Oceanic and Atmospheric Administration's
12 Regional Integrated Sciences and Assessment (RISA) program, known as the Climate Impacts
13 Group (UW-CIG). Over the course of nearly a decade, SPU and their collaborators refined a
14 model-driven vulnerability analysis that projects changes in global climate, downscaled those
15 changes to Seattle and its watersheds, and ran those projected changes through SPU's system
16 models to determine how climate change might affect SPU's water supply, water infrastructure,
17 and operations. The SPU study methodology represents a scenario approach to vulnerability
18 assessment.
19
20 4.4.1. Water Supply
21 Downscaled temperature and precipitation data were developed for the Puget Sound
22 region using three climate model/Special Report on Emissions Scenarios (SRES) combinations
23 and four time periods (IPCC, 2000). The model/SRES combinations include a
24 middle-of-the-road regional climate change scenario (MPIECHAM5/A2) with moderate
25 warming and precipitation increase, a significantly wetter and warmer scenario (TPSL-CM4/A2),
26 and a slightly drier and warmer scenario (GISS-ER/B1).10 The four time periods include 2000
27 (hindcast), 2025, 2050, and 2075. These models were selected because they performed well in
28 other studies replicating temperature and precipitation trends of the Pacific Northwest during the
29 20* century (Mote et al., 2005). A statistical downscaling approach was used to translate GCM
30 grid-scale output to a quasi-steady-state daily time series of temperature or precipitation for a
31 specific location at a specific future time that preserves the historic variability of climate
32 (Polebitski et al., 2007a; Polebitski et al., 2007b).
10Note that the A2 emission scenario is relatively high by the second half of the 21st century, while the Bl scenario
has the lowest level of greenhouse gas emissions of the SRES family.
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1 SPU's water supply planning model is the Conjunctive Use Evaluation (CUE) systems
2 model—a weekly time-step simulation model of the Cedar and Tolt River systems. However,
3 because CUE uses observed inflow data for both river systems as input, it cannot directly
4 incorporate climate model output (temperature and precipitation). Consequently, CIG ran the
5 downscaled meteorological data sets through its Distributed Hydrology Soils and Vegetation
6 Model (DHSVM) to produce climate-altered hydrologic data sets for use in CUE. CUE is used
7 for calculating the firm yield11 and reliability of Seattle's water supply system and potential
8 future water supply projects. CUE results indicated that yield decreased under all climate change
9 scenarios for all time periods. SPU also ran several planning scenarios through CUE to
10 determine whether available supply could be increased to compensate for anticipated supply
11 shortfalls.
12
13 4.4.2. Water Demand
14 SPU examined the effect of climate change on water demand using a dual approach of
15 regression analysis and forecast modeling. First, SPU performed a regression analysis of peak
16 season consumption for 1982-2007 using monthly consumption data, maximum temperature,
17 and rainfall at SeaTac Airport for May through September. This relationship was assumed to
18 hold in the future. SPU had already developed a demand forecasting model for its 2007 Water
19 System Plan, which forecasted nonclimate-altered demand change over time (SPU, 2006b).
20 Under this model, demand was forecasted to decrease below historic levels through 2050 but
21 increase above historic levels by 2075. Applying the results of the regression analysis to these
22 forecasts adjusts demand slightly upward due to the climate change scenarios in 2025 and 2050.
23 But, in 2075, the climate-induced increase accelerates in conjunction with significant increases in
24 baseline demand.
25
26 4.4.3. Storms and Runoff
27 SPU also engaged a consultant to use UW's Weather Research and Forecasting (WRF)
28 regional climate model to examine projected precipitation changes in the Thornton Creek
29 Watershed (Northwest Hydraulic Consultants, 2009). Note that this is a separate study from the
30 statistical downscaling study of water supply above but was deemed too uncertain for SPU's
31 planning purposes. This study focused on urban drainage, but it represents an advance over
32 previous water supply and climate change studies because of its use of dynamical instead of
33 statistical downscaling techniques. Northwest Hydraulic Consultants used output generated by
1 ^irm 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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1 two GCM/scenario combinations (CCSM3/A2 and ECHAM5/A1B) for two 31-year time periods
2 (1970-2000 and 2020-2050). This output was used in the WRF regional climate model to
r\
3 calculate temperature and precipitation data sets for two grid sizes of 20 and 36 km .
4 These data were used in the rainfall/runoff model Hydrologic Simulation
5 Program-Fortran (HSPF) to model changes in a number of creek parameters for the entire
6 Thornton Creek basin. The results of the study indicated that there would be increases in runoff,
7 except at one sub-basin where modeling results diverged, although the magnitude of the
8 increases varied by factors of two at times. According to the study's conclusions, "Additional
9 work is needed to improve confidence in future projections before applying dynamically
10 downscaled data to stormwater planning, policy, or design standards" (Northwest Hydraulic
11 Consultants, 2009). SPU is not currently using modeled climate projections for stormwater
12 planning purposes.
13
14 4.5. APPLICATION OF VULNERABILITY ASSESSMENT INFORMATION
15 SPU may have undertaken the most sophisticated vulnerability assessment of any of the
16 utilities discussed in this report and is the only one of the four utilities that directly used the
17 results to make an adaptation decision. SPU also identified more far-reaching adaptations to use
18 in future decades in case demand exceeds water supplies. Even prior to this analysis, SPU was
19 considering how to make the most effective use of usable storage, including the use of dynamic
20 rule curves that use current watershed state conditions instead of relying on past hydrologic
21 records. SPU also had a successful conservation program that had led to significant reductions in
22 demand since the mid-1980s and more recently, has committed to an additional 15 mgd of
23 conservation by 2030. The analysis also demonstrated what SPU already knew, that demand
24 could exceed supplies in 2075 even without climate change, with no new conservation programs
25 past 2030.
26
27 4.5.1. Water Supply
28 Based on the information generated by its water supply vulnerability assessments, SPU
29 determined that available water supply decreased under all scenarios for all time periods.
30 Projections for 2025 indicated Seattle's water supply would decrease by 6-10%, projections for
31 2050 indicated a decrease of 6-21%, and projections for 2075 indicated a decrease of 13-25%.
32 Demand was projected to decrease in 2025 and 2050 to around 83% of historic supply but
33 increase in 2075 to approximately 106% of historic supply.
34 Based on these projections, SPU analyzed "Tier 1" low- or no-cost intrasystem
35 modifications that effectively increased the usable storage capacity for water with no new supply
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1 infrastructure.12 This primarily consisted of eliminating conservative assumptions from SPU's
2 water system supply calculations.13 These low-cost modifications were estimated to compensate
3 for supply shortfalls in all three scenarios in 2025, in two out of three scenarios in 2050, and in
4 none of the three scenarios in 2075.
5 Other "Tier 2" alternatives were identified that could compensate for the remaining
6 projected shortfalls in 2050 and 2075. These included additional use of Lake Youngs storage,
7 modified/optimized conjunctive use operations, and additional conservation programs after 2030.
8 Even more expensive or complex alternatives were identified for "Tier 3," "Tier 4," and "Tier 5"
9 spanning from reservoir operational changes to new supply alternatives, but these higher-cost
10 modifications were deemed unnecessary through 2075.
11 All of these policy options were directly informed by the quantitative results of the SPU
12 vulnerability analysis. SPU has decided that its vulnerability analysis indicates no need for
13 near-term operational changes or new infrastructure. In one sense, SPU has not changed its
14 water supply planning and management decisions, because though significant, the projected
15 climate impacts are not imminent. On the other hand, the changes to conservative supply
16 planning assumptions represent an important class of no-regrets adaptations. Even the Tier 2
17 adaptations, such as increased water conservation efforts, represent policy options that provide
18 benefits in terms of supply reliability, regardless of the magnitude of climate change. In SPU's
19 current estimation, no adaptations beyond Tier 2 will be needed through 2075.
20
21 4.5.2. Storms and Runoff
22 The results of SPU's dynamical downscaling and urban drainage study provided
23 insufficient certainty to be useful for planning purposes. Consequently, SPU is relying on a
24 qualitative understanding that intense precipitation events are likely to increase and is exploring
25 a 1-15% increase in peak storm events as a proxy for changes in precipitation due to climate
26 change. This approach represents an important hedging strategy. In the absence of reasonably
27 high-certainty projections of future climate conditions, SPU decided to apply a safety factor to
28 new infrastructure construction to ensure that new investments would perform their intended
29 function over their useful lives based on a general understanding of the climate trends and a
30 reasonable estimate of the magnitude of that change.
31
12Tier 1 did include one structural adjustment—the raising of one overflow dike.
13Changes 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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1 5. SPARTANBURG WATER
2 Spartanburg Water is a public water and wastewater utility that is composed of
3 two distinct legal entities: Spartanburg Water System (SWS) and Spartanburg Sanitary Sewer
4 District (SSSD). The two entities function as one company (West, 2010). SSSD was formed as
5 a special-purpose district for wastewater services. SWS is a political subdivision of the City of
6 Spartanburg and is overseen by three Commissioners of Public Works, and SSSD is overseen by
7 the seven-member Sewer Commission, which includes the three Commissioners of Public Works
8 (Spartanburg Water, 2010a; West, 2010). Spartanburg Water can be defined as a medium-sized
9 utility.
10
11 5.1. BACKGROUND
12 Spartanburg Water serves a population of approximately 180,000 people in Spartanburg
13 County and portions of Greenville, Cherokee, and Union Counties in South Carolina
14 (Spartanburg Water, 2010a). The SWS water service area includes a contiguous retail service
15 area of approximately 259 mi2, a noncontiguous retail service area of approximately 15 mi2
9
16 (Spartanburg Water, 2010a), and a wholesale service area of approximately 605 mi . The SSSD
17 wastewater service area is defined by the Spartanburg city limits—a contiguous service area
18 covering approximately 196 mi2, and a noncontiguous service area of eight locations serving
r\
19 approximately 22 mi (Spartanburg Water, 2010a).
20 From 1971 to 2000, Spartanburg County received on average 61 in of rain per year
21 (SRCC, 2010). Precipitation is somewhat consistent throughout the year, ranging on average
22 from 3.44 to 6.86 inches per month (SRCC, 2010). The average minimum and maximum
23 temperatures are 48.6°F and 71.3°F, respectively (SRCC, 2010). In the last 10 years, however,
24 the Southeast region of the United States experienced prolonged droughts that lasted several
25 years. Spartanburg Water experienced droughts in 2002 and 2003, and there has been a
26 persistent drought since 2005, with the lowest recorded streamflow occurring in 2009 (West,
27 2010).
28
29 5.2. DESCRIPTION OF THE WATER SYSTEM
30 5.2.1. Water Supply System
31 Each day, Spartanburg Water provides approximately 30 million gallons of water to its
32 customers. Approximately 60% of the water use is residential (West, 2010). Industrial water use
33 has significantly declined in the past decade from 110 to 52 industrial accounts (West, 2010).
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1 Although there are commercial and other small business accounts, these sectors are not
2 significant water users.
3 Three reservoirs on the Pacolet River provide the vast majority of the Spartanburg water
4 supply (Figure 6). Bowen Reservoir, the most northern reservoir, is on the south fork of the
5 Pacolet River. Built in 1960, it covers 1,534 acres and has a total capacity of 17,115 acre-feet
6 (Spartanburg Water, 201 Ob; West, 2010). Water from Bowen Reservoir flows downstream to
7 Municipal Reservoir Number 1 (MR1), which is located just above the confluence of the North
8 and South Pacolet Rivers. Built in 1926, MR1 serves mainly as a pass-through reservoir with
9 approximately 1 day's worth of water. MR1 improves water quality through sedimentation as
10 the water flows through it (West, 2010). Blalock Reservoir is downstream from the confluence
11 of the North and South Pacolet Rivers and receives inflow from MR1 and the North Pacolet
12 River. Built in 1983, Blalock Reservoir covers 1,105 acres and has a total capacity of
13 16,894 acre-feet (Spartanburg Water, 2010b; West, 2010). Spartanburg Water expanded Blalock
14 Reservoir in 2006 by raising the height of dam to meet projected future water demand
15 (Spartanburg Water, 2009).
SPARTANBURG WATER SYSTEM
RESERVOIR WATERSHED
16
SC HWV 1
Figure 6. Reservoirs and watersheds of the Spartanburg water system.
Source: Spartanburg Water (2009).
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1 Two smaller water sources supplement the reservoir system: Vaughn Creek and an
2 unnamed stream off Hogback Mountain provide approximately 800,000-900,000 gallons per day
3 (gpd) of water. These sources supply the Landrum Water Treatment Plant (WTP), which has a
4 capacity of 1 million gallons per day (mgd). In addition, Landrum WTP has a groundwater
5 backup source with a pumping capacity of 50,000 gpd (West, 2010).
6 In addition to Landrum WTP, two other plants provide drinking water treatment.
7 R.B. Simms WTP, located at Bowen Reservoir, has a capacity of 64 mgd, and Blalock WTP,
8 located at Blalock Reservoir, has a capacity of 22.5 mgd. Spartanburg's three water treatment
9 plants provide full conventional treatment, including sedimentation, filtration, and chlorination
10 (West, 2010).
11 The distribution system is composed of 1,308 miles of pipes (West, 2010).
12 Hydroelectricity produced at R.B. Simms WTP is used to support the water treatment operations.
13 However, hydroelectricity is not generated when Spartanburg Water operates in full conservation
14 mode during droughts. This can have a significant effect on the utility's energy costs, especially
15 during peak hours, because peak usage can set the pricing for the month for all of its electricity
16 use (West, 2010).
17 Discharges from Blalock Reservoir are managed based on instream flow requirements
18 and the time of year. Releases are regulated based on a combination of factors, including the
19 water level in Blalock Reservoir, the time of year, and instream flow into the reservoir system.
20 Because of spawning offish downstream, the South Carolina Department of Health and
21 Environmental Control (SC DHEC) issued Spartanburg Water a permit that set the downstream
22 flow requirements and determined the 7Q1014 for Pacolet River. In the event of a persistent
23 drought, Spartanburg Water may request permission for reduced releases, provided it conducts
24 additional monitoring to ensure fish health and water quality (West, 2010).
25
26 5.2.2. Wastewater System
27 Spartanburg Water has 10 wastewater treatment plants (WWTPs) that range in capacity
28 from 50,000 gpd to 25 mgd. The largest of the 10 plants, Fairforest WWTP, is located just
29 downstream of Blalock Reservoir. All of the 10 WWTPs provide secondary treatment.
30 Discharge permits for the WWTPs are calculated based on the 7Q10, which is determined in part
31 by releases from the reservoirs; therefore, there is a relationship between Spartanburg Water's
32 ability to withdraw water and discharge wastewater. In total, approximately 13 mgd of
33 wastewater are collected, treated, and discharged into the Pacolet River (West, 2010).
14The 7Q10 is the lowest streamflow for 7 consecutive days that is expected to occur once every 10 years.
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1 Spartanburg Water owns, operates, and maintains 940 miles of wastewater collection
2 pipes throughout the service area (West, 2010). Some infiltration and inflow occur during storm
3 events. Although there is a separate storm sewer system, it is maintained by the city and county
4 and does not fall under Spartanburg Water's jurisdiction (West, 2010).
5
6 5.3. CLIMATE CHANGE PROJECTIONS AND RISKS
7 Spartanburg Water is aware that projected climate change may affect its water and
8 wastewater systems. The utility expects droughts in the region to increase in frequency and
9 severity with greater variability in precipitation. On the other hand, Spartanburg expects severe
10 storm events, such as hurricanes and tropical storms, to increase in frequency and severity as
11 well.
12 Spartanburg Water identified projected climate changes and their potential effects on its
13 water and wastewater systems and operations in a variety of ways. Networking within the water
14 utility community provided information on approaches other utilities are using to examine and
15 address climate change. For example, Spartanburg Water's Deputy General Manager of
16 Engineering and Technical Services served as the President of Water Environment Federation.
17 This provided her the opportunity to visit other domestic water utilities, including those in Las
18 Vegas, East Bay (California), and Seattle, in addition to water utilities in Europe, South Africa,
19 and Tanzania. Also, she and other Spartanburg Water staff often attend conferences to follow
20 the activities of and consult with other utilities (West, 2010). Also, one staff member attends
21 meetings of the South Carolina State Drought Response Committee, whose chair is the State
22 Climatologist and where projected climate change for the area is often discussed (Spartanburg
23 Water, 2010c).
24 Largely because of the prolonged and repeated droughts in recent years, Spartanburg
25 Water is considering the effects of climate change on its infrastructure and operations. The
26 droughts of the past decade have exacerbated many of the existing vulnerabilities of the
27 Spartanburg Water system, including increased water demand from population growth, changes
28 in land use patterns affecting water quantity and quality, and increasing frequency of droughts
29 and extreme storm events affecting quality and flooding (West, 2010).
30 Most of the expected effects of climate change will require increased management of
31 existing vulnerabilities, rather than addressing completely new challenges (West, 2010). For
32 example, one of Spartanburg's water conservation efforts for drought management is a pricing
33 structure with increasing block rates, which discourages water use beyond a certain, minimum
34 level and generally serves to discourage outdoor water use. With potential for more frequent or
35 more severe droughts with climate change, Spartanburg Water may implement this pricing
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1 structure along with other enhanced drought management approaches to conserve additional
2 water.
O
4 5.4. CLIMATE CHANGE VULNERABILITY ASSESSMENTS
5 Spartanburg Water believes the effects of climate change will exacerbate existing
6 vulnerabilities. As a result, rather than undertaking completely new activities or management
7 approaches, the utility is incorporating climate change in many of its existing management
8 activities. Climate change is now a consideration in all utility planning processes and
9 incorporating climate change is part of the utility's culture (West, 2010). To better consider
10 climate change in its decisions, Spartanburg Water attempts to stay current on regional climate
11 change proj ection data. In addition, it collects and tracks a variety of data relevant to climate
12 change, including rainfall, temperature, streamflow, reservoir levels, groundwater levels, water
13 usage, revenue streams, public perception, and Web site visits (West, 2010).
14 Spartanburg Water's consideration of climate change takes into account the potential
15 effects of climate change throughout its entire system—from providing sufficient water supplies
16 to ensuring an uninterrupted supply chain for treatment chemicals during extreme weather events
17 (West, 2010). This holistic approach to the system and operations—the result of Spartanburg
18 Water's past experiences (such as having an interrupted supply of treatment chemicals following
19 Hurricane Katrina) or lessons learned from other utilities—is essential because many aspects of
20 the system are interconnected. For example, the release of water from Blalock Reservoir for the
21 water system affects the 7Q10 determination for wastewater discharge permitting. Another
22 example of Spartanburg's system-wide thinking is its understanding of the potential effect of
23 water conservation programs on its revenue.
24 Spartanburg Water has a reservoir management model to support its management and
25 water use decisions throughout the supply system. It is also currently developing a hydraulic
26 model for the wastewater system. Combined with information on projected climate change,
27 Spartanburg Water believes these models of their existing systems will allow them to assess the
28 potential consequences of climate change on the system and allow the utility to consider
29 adaptation actions accordingly.
30
31 5.4.1. Water Quantity
32 One of the primary considerations for the water supply system is sufficient water
33 quantity. In the last 10 years, population growth has increased water demand in the Spartanburg
34 Water service area and in six other water districts in the county downstream of Spartanburg
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1 Water. In addition, continued development has led to more impervious surfaces, which have
2 redirected runoff outside of the reservoirs' watersheds, thereby reducing supply.
3 The recent prolonged drought experienced in the region has affected not only surface
4 water but groundwater resources as well. While the main water source for the Spartanburg
5 Water system is surface water, groundwater contributes to baseflow and, therefore, surface water
6 supplies. Multiple and prolonged years of drought impact groundwater supplies, which can take
7 several years to recover. This results in a continued risk to surface water supply sources beyond
8 the length of the drought (West, 2010). Also, during these drought periods, people living within
9 Spartanburg County who obtain their drinking water from groundwater sources and are not
10 serviced by Spartanburg Water request to be added as a customer because groundwater sources
11 are insufficient. Often these requests originate from areas where water distribution systems do
12 not already exist. This can be a challenging issue to manage, because often public expectations
13 are for the utility to provide access to water (West, 2010).
14 Change in water quantity may also affect wastewater system operations. Several of
15 Spartanburg Water's WWTPs discharge to small streams, where wastewater discharges may
16 constitute up to 80% of streamflow (West, 2010). With prolonged drought, Spartanburg Water
17 anticipates that the future permit limits for these facilities will change if the 7Q10 changes for the
18 receiving streams. In an adjacent county, similar conditions resulted in the wastewater utility
19 upgrading to tertiary treatment. Some of the 7Q10 determinations are expected to undergo
20 review in 2012. The result of these reviews may require additional capital planning and
21 "creative treatment strategies in the interim" (West, 2010).
22
23 5.4.2. Water Quality
24 In addition to drought conditions, the Spartanburg Water service area has experienced
25 extreme rain events, including tropical storms and hurricanes. These events caused flooding
26 throughout the area and damaged components of Spartanburg Water's facilities (West, 2010).
27 With the increased frequency and severity of such storms projected to happen because of climate
28 change, preventive and restorative efforts will require additional planning and financing. In
29 addition, when combined with continued land development, water quality problems resulting
30 from impervious surface runoff will be exacerbated. Impervious surfaces are a significant water
31 quality concern because there is more runoff of sediments, contaminants, oil, and grease.
32 Because there are no zoning laws in Spartanburg County, land use changes can be unpredictable
33 in some areas (West, 2010).
34 Extreme storm events and droughts, especially in combination, have been associated with
35 taste and odor problems in Bowen Reservoir and MR1. The problems are caused by high levels
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1 of geosim, which is a naturally occurring compound produced by certain soil bacteria and
2 blue-green algae, depending on environmental conditions, including water temperatures, nutrient
3 enrichment, and turbidity (USGS, 2009). SC DHEC determined that both reservoirs were fully
4 supportive of all uses based on established criteria. An investigation by Spartanburg Water and
5 the U.S. Geological Survey found that nutrient enrichment was not the contributing cause of the
6 elevated geosim levels but that streamflow and the resulting hydraulics within the reservoir
7 system affect the production and release of geosim by blue-green algae (West, 2010). The
8 hydraulics affect sedimentation or re-suspension of sediment, which, in turn, affect the
9 penetration of sunlight and the temperature of the water—both factors in the release of geosim.
10 Today, Spartanburg Water has a monitoring system in place that helps predict when geosim
11 events may occur.
12 The two main weather events that can trigger geosim release are (1) droughts, when
13 water clarity is greatly increased by lower reservoir levels and slower streamflow; and (2) major
14 storm events, when hydraulic surges stir up sediment in the system, releasing phosphorus and
15 resulting in an increased abundance of blue-green algae. The highest levels of geosim were
16 observed in 2003-2005 when droughts in 2002 and 2003 were followed by tropical storms
17 (West, 2010). Because these two main contributing factors are both predicted to increase in
18 severity and frequency, Spartanburg Water expects that climate change may exacerbate the
19 geosim water quality problem and may require additional management.
20
21 5.4.3. Infiltration/Inflow
22 With projected increases in the intensity of storm events, Spartanburg expects infiltration
23 and inflow into the wastewater collection system to increase. This may threaten the capacity of
24 the system to handle wastewater flow during these events.
25
26 5.5. APPLICATION OF VULNERABILITY ASSESSMENT INFORMATION
27 Spartanburg Water does not expect climate change to introduce new challenges but rather
28 to exacerbate existing vulnerabilities. Given both its climate experiences of the past 10 years in
29 the form of increased frequency and duration of drought and its information about projected
30 climate change, Spartanburg Water has initiated a utility-wide effort to incorporate climate
31 change into its planning processes. Spartanburg Water has combined its environmental,
32 operational, and financial data with its understanding of the water system to qualitatively assess
33 the potential effects of projected climate change on its system, its operations, and customer
34 needs. It has also changed its planning and management, particularly by increasing the
35 flexibility of its system and operations.
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1 As part of long-term water supply planning, in 2006, Spartanburg Water doubled the
2 capacity of Blalock Reservoir, based on a study conducted in the 1990s. When this project was
3 completed, Spartanburg Water rethought its management strategy for the reservoir system as a
4 result of extended droughts in the Southeast. Based on a set of indicators, including streamflow
5 and long-term weather forecasts, reservoir releases are managed for maximum water storage
6 when signs of prolonged drought are present and hydroelectric power generation may be
7 suspended. (Hydroelectric power is used to pump water into the distribution or storage system.)
8 Also, because Bowen and Blalock Reservoirs support recreational activities and adjoining
9 properties are permitted to directly withdraw water from the reservoirs for lawn irrigation,
10 recreational activities were limited, and water conservation requirements were instituted.
11 Spartanburg Water also asserted its right to discontinue all withdrawals for lawn irrigation from
12 the reservoirs during droughts (West, 2010).
13 In addition, Spartanburg Water revised its Water Demand Management Plans and became
14 a WaterSense® Partner and Charter Sponsor of The Alliance for Water Efficiency. Aggressive
15 water conservation campaigns were launched throughout the community, including educational
16 kiosks that rotated through public areas. Spartanburg Water promotes water conservation
17 year-round activities, regardless of drought conditions.
18 As a result of the conservation program and decreased industrial water use, Spartanburg
19 Water has realized a reduction of 10 mgd in water use, and the summer peak demand has been
20 reduced by 5 mgd. Because of this decreased demand, the time that water resides in the
21 distribution system has increased, so Spartanburg Water is considering taking some ground
22 storage offline and/or retrofitting lines to minimize this time. These lines and storage options,
23 however, will be maintained in place for future use. This may prove useful, with potential
24 increases in water demand from new customers or increased demand with climate change. In the
25 next 4 years, Spartanburg Water plans to spend $3 million on its water distribution system
26 (Spartanburg Water, 201 Od).
27 The combination of Spartanburg Water's successful water conservation program and loss
28 of many industrial accounts has resulted in a sustained loss of approximately 13% of the utility's
29 usual revenues in the last 2 years. Spartanburg Water is now re-evaluating its revenue streams
30 and management strategies to ensure not only environmental but also financial sustainability
31 (West, 2010).
32 On the wastewater side of the system, Spartanburg Water has plans to evaluate the
33 feasibility of modifying future treatment at 3 of the 10 WWTPs (Spartanburg Water, 2010e).
34 The three benefits cited in the CIP include the assurance of the effectiveness of ultraviolet light
35 disinfection at these plants, potential future reuse of water, and continued compliance with
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1 discharge permits by providing "additional treatment that may be needed with fluctuations in
2 stream flows from climate impacts" (Spartanburg Water, 2010e).
3 To address the potential increase in infiltration and inflow into the wastewater collection
4 system, Spartanburg Water adopted a new strategy when upgrading pipes in the wastewater
5 collection system. Instead of closing off the old pipes, they were left in place to provide
6 additional capacity during storm events and additional flexibility in managing the projected
7 effects of climate change.
8 Spartanburg Water has been able to gather information on climate change impacts and
9 adaptation by attending state-level drought committee meetings and networking with other water
10 utilities. It does not, however, have the benefit of a state-level water program that assesses
11 available water resources or provides guidance on projected climate change. This limits
12 Spartanburg Water's long-term planning and modeling. Spartanburg Water notes that the most
13 helpful resources for continuing to address climate change would be the availability of more
14 environmental data, descriptions of best practices and management tools, and case studies of
15 other utilities' actions. In addition, addressing overlapping regulations and coordinating
16 regulations on a watershed basis among surface water, groundwater, wastewater, stormwater,
17 and other water resource-related programs would facilitate Spartanburg Water's efforts to
18 manage its water resources efficiently and sustainably in the face of continued climate change
19 (West, 2010).
20
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SUMMARY
3 Each of the utilities featured in this report is faced with a unique set of issues and
4 challenges related to climate change. While the issues and challenges vary, a number of
5 summary observations can be made that may be useful to other utilities and members of the
6 water resources community regarding the conduct and use of climate change vulnerability
7 assessments to support adaptation.
8
9
10 • For the four utilities researched for this report, conducting climate change vulnerability
1 1 assessments appears to have increased awareness of climate change risks, informed
12 decision making, and provided support for adaptation measures. These case studies
13 illustrate the wide range of issues and constraints faced by utilities and approaches for
14 considering adaptation to climate change in a holistic context, taking into account all
15 factors affecting system performance.
16 • Utilities have benefitted by working with climate change researchers. Seattle Public
17 Utilities (SPU) collaborated with the Climate Impacts Group at the University of
18 Washington, New York City Department of Environmental Protection (DEP)
19 collaborated with Columbia University and the City University of New York, and East
20 Bay Municipal District (EBMUD) used an analysis conducted by the State of California
21 and the California Climate Change Center. In contrast, Spartanburg relied on information
22 gathered from briefings and staff contact with other utilities through participation in the
23 Water Environment Federation and the American Water Works Association but did not
24 formally collaborate with the climate change research community to develop information
25 on climate change risks.
26 • The large utilities used a wide array of climate change scenarios to capture some of the
27 uncertainty about future climate change. However, EBMUD also conducted a sensitivity
28 analysis to improve its understanding about how particular elements of its water resource
29 system could be affected by climate change. SPU and DEP conducted what is often
30 referred to as "top-down" approaches driven by climate change scenarios and models.
31 • The utilities used models to manage and understand the dynamics of their systems. All of
32 the case studies except Spartanburg used their models to evaluate the effects of potential
33 climate change on their systems. The models were used to assess whether operational
34 changes would be sufficient to cope with the effects of climate change, or whether system
35 changes, such as adding supplies or further reducing demand, were also necessary.
36 • A review of literature on climate change and understanding of how recent extreme events
37 could become worse in the future informed Spartanburg 's adaptation analysis. This
38 suggests that while modeling appears to be useful to provide insights into vulnerability, it
39 is not necessary. Education on climate change risks can be a substitute. To be sure,
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1 quantitative analysis can provide more detailed results and can identify possible surprises
2 arising from climate change. Nevertheless, the Spartanburg example demonstrates that
3 utilities lacking the financial and staff resources to support detailed modeling studies can
4 still considerably reduce their vulnerability to the potential impacts of climate change by
5 increasing their knowledge of potential risks.
6 • Utilities expressed an interest in obtaining better information on climate change, and that
1 their needs are reflected in future research. They particularly requested information on
8 projections at the spatial and temporal scales in which they operate, the probability of
9 specific changes in climate, and guidance on appropriate climate change parameters and
10 scenarios to consider and plan for in their regions. It was recommended that a central
11 repository of data be created to support climate change and adaptation analysis. Utilities
12 need transparent information on how data are collected and what their appropriate uses
13 are.
14 • Overall, the case studies presented in this report suggest that while there is uncertainty
15 about how climate will change in different regions of the country, through analysis and
16 detailed study, utilities are able to improve their understanding of the risks they will
17 likely face from climate change, and make informed decisions about how to best adapt to
18 climate change so as to minimize their potential losses. This will help them make
19 informed decisions about how to best adapt to climate change so as to minimize their
20 potential losses.
21 • The results of vulnerability assessments by the four utilities presented in this report were
22 used in different ways to inform and support adaptation. Seattle responded specifically
23 to the results of the vulnerability analysis by evaluating the impact that conservative
24 assumptions have on reservoir management. Vulnerability assessments conducted by the
25 other utilities appeared to have increased awareness of climate change risks, informed
26 decision making, and provided support for adaptation measures.
27
28
29
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28 http://www.climate.tag.washington.edu/techmemos/Final_Report 12-13-07_.pdf.
29 Parry, ML; O Canziani, JP; Palutikof, C; et al; eds. (2007) Climate change 2007: Impacts, adaptation and
3 0 vulnerability. Contribution of Working Group II to the fourth assessment report of the intergovernmental panel on
31 climate change. New York: Cambridge University Press. Available online at http://www.ipcc.ch/ipccreports/ar4-
32 wg2.htm.
33 PlaNYC. (2007a) Climate change. Reduce global warming emissions by more than 30%. Available online at
34 http://www.nyc.gov/html/planyc2030/downloads/pdf/report_climate_change.pdf.
3 5 PlaNYC. (2007b) Water network. Available online at
3 6 http://www.nyc.gov/html/planyc2030/html/plan/water_network.shtml.
37 PlaNYC. (2008) Sustainable stormwater management plan 2008. Available online at
38 http://www.nyc.gov/html/planyc2030/downloads/pdf/sustainable_stormwater_plan.pdf.
This document is a draft for review purposes only and does not constitute Agency policy.
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1 PlaNYC. (2008-2010) Progress reports for 2008 through 2010. Available online at
2 http://www.nyc.gov/html/planyc2030/html/downloads/download.shtml.
3 Polebitski, A; Traynham, L; Palmer, RN. (2007a). Technical memorandum #4: approach for developing climate
4 impacted meteorological data and its quality assurance/quality control. A report prepared by the Climate Change
5 Technical Subcommittee of the Regional Water Supply Planning Process. Seattle, WA. Available online at
6 http://www.govlink.org/regional-water-planning/tech-committees/climate-change/UWreports/TechnicalMemo4(12-
7 13-07).pdf.
8 Polebitski, A; Wiley, MW; Palmer, RN. (2007b) Technical memorandum #2: methodology for downscaling
9 meteorological data for evaluating climate change. A report prepared by the Climate Change Technical
10 Subcommittee of the Regional Water Supply Planning Process. Seattle, WA. Available online at
11 http://www.govlink.org/regional-water-planning/tech-committees/climate-change/UWreports/TechnicalMemo2(12-
12 13-07).pdf.
13 Rosenzweig, C; Major, DC; Demong, K; et al. (2007) Managing climate change risks in New York City's water
14 system: assessment and adaptation planning. Mitigat Adapt Strat Global Change 12(8):1391-1409.
15 RWSP (Regional Water Supply Planning). (2010) Regional waiter supply planning. Seattle, WA. Available online
16 at http ://www. govlink. org/regional-water-planning/index. htm.
17 Smit, B; Pilifosova, O; Burton, I; et al. (2001) Adaptation to climate change in the context of sustainable
18 development and equity. In: McCarthy, J; Canziana, N; Leary, NA; et al; eds. Climate change 2001: impacts,
19 adaptation, and vulnerability, chapter 18. New York: Cambridge University Press; pp 877-912. Available online at
20 http://www.grida.no/climate/ipcc_tar/wg2/pdf/wg2TARchapl8.pdf.
21 Spartanburg Water. (2009) Lake Blalock buffer management plan. Public works of the city of Spartanburg, SC.
22 September 2009. Accessed March 10. Available online at http://www.sws-sssd.org/pdfs/lbbmp.pdf.
23 Spartanburg Water. (2010a) Spartanburg water system/Spartanburg sanitary sewer district service areas. Public
24 works of the city of Spartanburg, SC. Accessed March 10. Available online at http://www.sws-sssd.org/water-
25 sewer/index.html.
26 Spartanburg Water. (2010b) Spartanburg lakes. Public works of the city of Spartanburg, SC Accessed March 10.
27 Available online at http://www.sws-sssd.org/lakes/index.html.
28 Spartanburg Water. (2010c) Drought Committee summary. Received via e-mail from Rebecca West, Deputy
29 General Manager of Technical and Engineering Services, on April 22.
3 0 Spartanburg Water. (20 lOd) SWS 10 year CIP August 2009. Received via e-mail from Rebecca West, Deputy
31 General Manager of Technical and Engineering Services, on April 22.
32 Spartanburg Water. (2010e). Operations CIP items table. Received via e-mail from Rebecca West, Deputy General
3 3 Manager of Technical and Engineering Services, on April 22.
34 SPU (Seattle Public Utilities). (2006a) Water shortage contingency plan: supplement to the Seattle public utilities
3 5 2007 water system plan. City of Seattle, Washington. July. Available online at
36 http://www.cityofseattle.net/util/stellent/groups/public/@^
37 ershor_200312021018123.pdf.
3 8 SPU (Seattle Public Utilities). (2006b) SPU 2007 water system plan. City of Seattle, Washington. November.
39 Available online at
40 http://www.cityofseattle.net/util/About_SPU/Water_System/Plans/2007WaterSystemPlan/index.asp.
This document is a draft for review purposes only and does not constitute Agency policy.
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1 SPU (Seattle Public Utilities). (2008) South Fork Tolt watershed management plan. Prepared by Tetra Tech
2 Infrastructure Group and Triangle Associates. City of Seattle, WA. November. Available online at
3 http://www.cityofseattle.net/util/stellent/groups/public/@spu/@ssw/documents/webcontent/spu01_004082.pdf.
4 SPU (Seattle Public Utilities). (2010a) Demographics and water use statistics. City of Seattle, WA. Available online
5 at
6 http://www.seattle.gov/util/About_SPUAVater_Systern/History_&_Overview/DEMOGRAPHI_200312020908145.a
7 sp.
8 SPU (Seattle Public Utilities). (2010b) History of the watershed. City of Seattle, WA. Available online at
9 http://www.seattle.gov/util/About_SPUAVater_System/Water_Sources_&_Treatment/Cedar_River_Watershed/COS
10 _001714.asp.
11 SPU (Seattle Public Utilities). (2010c) Tolt River watershed. City of Seattle, WA. Available online at
12 http://www.seattle.gov/util/ About_SPU/Water_System/Water_Sources_&_Treatment/Tolt_River_Watershed/index.
13 asp.
14 SPU (Seattle Public Utilities). (20lOd) Tolt treatment facility. City of Seattle, WA. Available online at
15 http://www.seattle.gov/util/ About_SPU/Water_System/Water_Quality/Tolt_Treatment_Facility/index.asp.
16 SPU (Seattle Public Utilities). (20lOe) Water system history. City of Seattle, WA. Available online at
17 http://www.seattle.gov/util/About_SPU/Water_System/History_&_Overview/WATERSYST_200312020908156.as
18 p.
19 SRCC (Southeast Regional Climate Center). (2010) Landrum, South Carolina 1971-2000 Monthly Climate
20 Summary. Accessed May 3. Available online at http://www.sercc.com/.
21 Stewart, I.T., D.R. Cayan, and M.D. Dettinger. (2004) Changes in snowmelt runoff timing in western North
22 America under a 'business as usual' climate change scenario. Clim Change 62:217-232. Available online at
23 http://meteora.ucsd.edu/cap/stewart_clch.pdf.
24 Stratus Consulting. (2010) Climate change vulnerability assessments: a review of water utility practices. Prepared
25 for Jill Neal, EPA Office of Research and Development.
26 Towey, A. (2010) Water reuse, EBMUD. Personal communication on April 9, 2010.
27 U.S. EPA (Environmental Protection Agency). (2002) Cases in water conservation: how efficiency programs help
28 water utilities save money and avoid costs. Available online at
29 http://www.epa.gov/WaterSense/docs/utilityconservation_508.pdf.
30 U.S. EPA (Environmental Protection Agency). (2009a) New York City watershed. Region 2. Available online at
31 http://www.epa.gov/Region2/water/nycshed/.
32 U.S. EPA (Environmental Protection Agency). (2009b) Proceedings of the first national expert and stakeholder
3 3 workshop on water infrastructure sustainability and adaptation to climate change. Office of Water, Washington, DC;
34 EPA 600/R-09/010. Available online at http://www.epa.gov/nrmrl/wswrd/wqm/wrap/workshop.html.
3 5 USGS (U.S. Geological Survey). (2009) Taste and odor occurance in Lake William C. Bowen and Municipal
36 Reservoir #1, Spartanburg County, South Carolina. USGS Fact Sheet 2009-3043. Available online at
3 7 http://pubs.usgs.gov/fs/2009/3043/.
3 8 UW-CIG (University of Washington Climate Impacts Group). (20 lOa) About Pacific Northwest climate. Joint
39 Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle. Available online at
40 http://cses.washington.edu/cig/pnwc/pnwc.shtml.
This document is a draft for review purposes only and does not constitute Agency policy.
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1 UW-CIG (University of Washington Climate Impacts Group). (2010b). Case study: Seattle public utilities. Joint
2 Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle. Available online at
3 http://cses.washington.edu/cig/fpt/casestudyspu.shtml.
4 UW-CIG (University of Washington Climate Impacts Group). (2010c) Climate change. Joint Institute for the Study
5 of the Atmosphere and Ocean, University of Washington, Seattle. Available online at
6 http://cses.washington.edu/cig/pnwc/cc.shtml.
7 WA DOE (Washington State Department of Ecology). (2001) Appendix B: Summary of major ASR projects in
8 Washington. Appendix to ASR 2001 Report to the Legislature.
9 http://www.ecy.wa.gov/programs/wr/asr/images/pdf/ASRLegRptApdx.pdf.
10 Wallis, MJ; Ambrose, MR; Chan, CC. (2008). Climate change: charting a water course in an uncertain future.
11 JAWWA 100(6):70-79. http://www.ebmud.com/sites/default/files/pdfs/Jourml-06-08 J).pdf
12 Water-technology.net. (2010) Croton water filtration plant, New York, USA. Available online at http://www.water-
13 technology.net/projects/crotonfiltration/.
14 West, R. (2010) Deputy General Manager of Engineering & Technical Services, Spartanburg Water. Personal
15 communication on April 1.
16 WRCC (Western Regional Climate Center). (2010) Western U.S. climate historical summaries. Available online at
17 http://www.wrcc.dri.edu/Climsum.html.
18 WUCA (Water Utility Climate Alliance). (2010) About us. Accessed May 3, 2010. Available online at
19 http://www.wucaonline.org/html/about_us.html.
20
This document is a draft for review purposes only and does not constitute Agency policy.
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