xvEPA
United States
Environmental Protection
Agency
Climate Resilience Evaluation and Awareness Tool Exercise with
Los Osos Water Purveyors and the Morro Bay National Estuary
Program
CLIMATE READY
WATER UTILITIES
vv-EPA
CLIMATE READY
ESTUARIES
Office of Water (4608-T) | EPA 817-B-13-003 | June 2013
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Table of Contents
Foreword 1
1. Introduction 1
1.1 Project Background 2
1.2. Morro Bay- Geographic Description 3
1.3 Los Osos Groundwater Basin Management Plan - Context 4
2. CREAT Exercise Results 5
2.1 Scenario Planning, Time Periods, and Consequence Weighting 5
2.1.1. Scenario Planning 6
2.1.2 Time Periods 6
2.1.3 Consequence Weighting 6
2.2 CREAT and Cal-Adapt Climate Data for the SEAWAT Analysis 8
2.3 Sea Level Rise Projections - California 9
2.4 Prioritizing Assets and Threats for the Analysis 9
2.5 Existing and Potential Adaptive Measures 9
2.6 Using CREAT and SEAWAT Together 10
2.6.1 SEAWAT Analysis 11
2.6.2 SEAWAT Results Summary 11
2.7 Baseline and Resilience Analysis Discussion 12
2.7.1 Re-Assessing Consequence Levels 12
2.7.2 Adaptive Measure Contribution 14
2.7.3 Examining Risk Reduction - Resilience Analysis 14
2.8 Implementation Planning - Adaptation Packages 15
2.9 Results and Reports 17
3. Lessons Learned and Conclusions 18
3.1 Future Use of CREAT and SEAWAT in Morro Bay 18
3.2 Feedback from Participants and Next Steps 18
3.3. Conclusion 18
Appendices
Appendix A. Project Participants List
Appendix B. SEAWAT Results Memo
Appendix C. CREAT-Cal Adapt Monthly Comparison
Appendix D. Baseline and Resilience Consequence Weighting Proposed Changes
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Climate Ready Water Utilities - Climate Ready Estuaries GREAT Exercise Report
Foreword
Current watershed management practices may not be sufficient to cope with the potential effects
of climate change on ecosystems, water supply, water quality, and coastal flooding. As a result,
there is a need to identify regional consequences from climate change and to develop adaptation
strategies that can be integrated at a watershed scale. The U.S. Environmental Protection
Agency's (EPA) Climate Ready Water Utilities (CRWU) and Climate Ready Estuaries (CRE)
initiatives coordinated their efforts and engaged water resource stakeholders in a climate change
adaptation exercise in Morro Bay, California. Both EPA initiatives focus on addressing climate
change and water resource issues with stakeholders that share common interests regarding
watershed management. This report details a recent climate change adaptation exercise that
provided an opportunity for these parties to collaborate on assessment and planning with respect
to potential climate change impacts on natural resources and utility infrastructure.
EPA's CRWU and CRE initiatives collaborated with a workgroup comprised of regional water
purveyors, as well as representatives from the Morro Bay National Estuary Program (NEP). To
better facilitate the exercise, EPA used two tools: the Climate Resilience Evaluation and
Awareness Tool (GREAT) and results from the U.S. Geological Survey's SEAWAT model.
EPA used GREAT as the framework to identify climate change threats and vulnerable assets, and
to evaluate adaptation options throughout the Los Osos Groundwater Basin. SEAWAT was used
to assess potential changes in groundwater quality due to projected climate change impacts from
saltwater intrusion and changes in groundwater recharge dynamics. The SEAWAT analysis also
helped to support the identification of potentially vulnerable assets and assisted the workgroup to
use adaptation planning to address potential vulnerabilities. The qualitative aspects of GREAT's
risk assessment framework combined with quantitative inputs from the SEAWAT modeling
analysis provided stakeholders with valuable information and insights regarding water resources
management in the Los Osos Basin. These insights will help to inform the current and ongoing
development of the Los Osos Groundwater Basin Management Plan.
To address projected climate change impacts, workgroup participants discussed potential
adaptive measures that may be implemented in the future. Preliminary results from the GREAT
analysis indicate that the implementation of these potential adaptive measures will reduce risk
among the selected vulnerable assets and threats from climate change. Further discussions of
these adaptive measures is warranted, as stakeholders recognized that some options may be
beneficial by increasing basin safe yield, but could prove to have potentially harmful effects to
Morro Bay ecosystems. Participants also noted the value of the collaborative process throughout
the GREAT exercise process, especially as the workgroup identified vulnerable assets and
climate change threats in Los Osos Basin, refined definitions related to consequence levels, and
applied data analysis (SEAWAT) to the risk assessment and planning framework supported by
GREAT.
1. Introduction
To assess projected climate change impacts and build upon ongoing water resources
management efforts in Morro Bay, California, EPA's Climate Ready Water Utilities (CRWU)
and Climate Ready Estuaries (CRE) initiatives collaborated with a workgroup comprised of
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representatives from the Morro Bay National Estuary Program (NEP), Los Osos Water
Purveyors,1 and contractors to identify consequences from climate change, develop adaptation
strategies at the watershed level, and inform the Los Osos Groundwater Basin Management Plan.
This exercise provided a framework for climate change risk assessment and adaptation planning
through a series of webinars held from January through May 2012, as well as follow-on
discussions that continued through September 2012.
During this exercise, the workgroup used EPA's Climate Resilience Evaluation and Awareness
Tool (CREAT) and the U.S. Geological Survey's (USGS) SEAWAT model to leverage both
CREAT's qualitative vulnerability assessment approach and SEAWAT's quantitative data.
CREAT was used as a framework to bring together a larger group of watershed stakeholders to
explore an expanded scope of risk management and planning activities at drinking water utilities
in Morro Bay. SEAWAT was used to assess potential changes in groundwater from potential
saltwater intrusion and changes in groundwater recharge dynamics due to projected climate
change. The SEAWAT results were also used to provide information regarding current and
projected safe yield in the Los Osos Basin, which will inform the development of the Los Osos
Groundwater Basin Management Plan. For more information on the SEAWAT analysis results,
see Section 2.6 and Appendix B.
Note: Throughout this exercise, inputs to Morro Bay's CREAT analysis file were suggested by
various members of the workgroup. These inputs are not necessarily exhaustive of all possible
inputs and can be revised in the future.
1.1 Project Background
The Los Osos aquifer system is comprised of porous tertiary and quaternary age geologic units
overlying significantly less porous bedrock. The aquifer is an east/west trending basin that rises
in elevation gradually toward the west.2 The aquifer is subdivided into five zones, A through E.
These subdivisions are separated by a range of low permeability layers. Three-fourths of the
municipal and agricultural groundwater is currently drawn from the lower aquifer in Zones D
and E, while approximately one-third is drawn from the upper aquifer in Zone C. While the
upper-most zones, A and B, only supply a few private wells, they are important sources of
groundwater flows to environmentally sensitive habitats and to the main production aquifers
below.
Current and projected threats to Morro Bay's water resources will be exacerbated by climate
change impacts. The only freshwater input to the hydrologic cycle of the Los Osos Valley is
precipitation, as there are no interbasin transfers of water into the valley. As a result, changes in
precipitation directly impact aquifer recharge rates in the Los Osos Basin communities that rely
1 Los Osos Water Purveyors group includes representatives from the following water utilities in and around Morro
Bay: Golden State Water, S&T Mutual Water, and Los Osos Community Services District. For a list of project
participants, see Appendix A.
2 California Department of Water Resources. 2004. California's Groundwater, Bulletin 118, Central Coast
Hydrologic Region, Los Osos Groundwater Basin: Drought: Year 3.
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on the aquifer for drinking water. Climate change and precipitation trends and patterns must be
considered when planning for the future.3
In addition, the Los Osos upper aquifer suffers from nitrate pollution from septic systems, and
overdraft of the lower aquifer has caused saltwater intrusion. Increased population growth
combined with increased drought and sea level rise may make current saltwater intrusion
conditions worse. Additionally, potential future declines in precipitation combined with
increasing average air temperatures have the potential to impact groundwater recharge in Los
Osos Basin, making water supplies even more scarce. While diverting wastewater to a new
treatment plant may begin to address nitrate contamination issues from septic systems in the
Basin, the diversion may alter current groundwater dynamics and groundwater flow to the Bay.
Los Osos Water Purveyors may also need to change pumping regimes to avoid saltwater
intrusion. For example, changes could include relocating certain wells and/or pumping more
from wells not impacted by saltwater intrusion. These new pumping regimes may require other
adaptive measures, such as water reuse in the Los Osos Creek Valley, to avoid adversely
impacting creek flow already suffering from climate change-related impacts. These threats to
Morro Bay's water resources were considered throughout the exercise; however, for the purpose
of the GREAT analysis, members of the workgroup chose to analyze two specific climate change
threats - degraded water quality from saltwater intrusion and reduced groundwater recharge from
drought.
1.2. Morro Bay - Geographic Description
The 48,000-acre Morro Bay watershed is located along the central coast of California. Two
major creeks drain into the bay. Chorro Creek and its tributaries drain 60% of the Morro Bay
watershed. Los Osos Creek and its tributaries drain the remaining 40%. There are two small
urban areas in the watershed, and the rest of the area is farm, ranch, and public land including
state facilities such as a prison, university, and National Guard base. The city of Morro Bay on
the Chorro Valley side is home to approximately 10,000 residents. Morro Bay is connected to a
wastewater treatment plant that utilizes partial secondary treatment and has stormwater
infrastructure. The Los Osos Community Service District (Los Osos CSD) on the Los Osos
Valley side contains roughly 15,000 residents, relies completely on septic systems, and has
limited-to-no stormwater infrastructure.
3 ENVS, CSUMB Class, et al. 2010. The Watershed Institute, Division of Science and Environmental Policy,
California State University, Monterey Bay.
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Image 1. Morro Bay National Estuary
1.3 Los Osos Groundwater Basin Management Plan - Context
The treatment and use of water in the Los Osos area of the watershed has been a complex issue
throughout the history of the community. As previously mentioned, the densely developed areas
of Los Osos currently rely on septic systems. These septic systems pollute the shallow aquifer
with nitrates. In 1988, the Regional Water Quality Control Board placed a moratorium on
building in this area until a wastewater treatment plant was constructed. Since then, the
community has undergone a contentious public process delaying sewer infrastructure. However,
San Luis Obispo County is currently moving forward with plans to build a wastewater treatment
plant. These plans include potential water reuse and additional water conservation measures.
Once the wastewater system is built and the growth moratorium is lifted by the Regional Water
Quality Control Board, the county may or may not adopt growth restrictions to protect the
aquifers from being overdrawn. Additionally, there is an ordinance on development outside the
moratorium area that requires any new development project to implement conservation retrofits.
There are currently three water purveyors in the Los Osos Basin, two private companies and one
public entity. Golden State Water Company (GSWC) services 8,821 customers. S&T Mutual
Water Company services 221 customers, and the Los Osos Community Services District (CSD)
services 7,657 customers. Image 2 geographically illustrates the relative location of each water
purveyor's service area.
Due to lawsuits over water pumping, the three purveyors are currently involved in a court
mandated Interlocutory Stipulated Judgment (ISJ). The three parties are working with San Luis
Obispo County to develop and implement a basin management plan for the Los Osos
Groundwater Basin. The objectives of the basin plan include identifying safe yield for the water
resources, providing for sustainable use, stopping saltwater intrusion, managing and preventing
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contamination, identifying water conservation practices, and protecting environmentally
sensitive areas.
Image 2. Map of Los Osos Water Purveyors
Image Credit: Los Osos Community Services District
2. CREAT Exercise Results
With the goal of informing the Los Osos Groundwater Basin Management Plan, the Morro Bay
workgroup used CREAT and SEA WAT results during this exercise to examine climate change
impacts to water resources. More specifically, the workgroup examined how saltwater intrusion
may be exacerbated and basin yield reduced by projected sea level rise (SLR) and potential changes in
temperature and precipitation. The workgroup then used CREAT's risk assessment framework
to discuss the implementation of potential adaptive measures to reduce risk from climate change
impacts.
2.1 Scenario Planning, Time Periods, and Consequence Weighting
During GREAT's Setup step, users can select basic settings which include scenario planning,
time period selection, and consequence weighting. Each of these setup features is described
below in more detail.
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2.1.1. Scenario Planning
GREAT provides two options for assessing the likelihood of specific climate change threats.
The Morro Bay workgroup selected GREAT's "scenario-based" approach, which assumes that
Morro Bay's threats of degraded water quality from saltwater intrusion and drought-induced
reduced groundwater recharge will occur in the time periods considered. Unless GREAT users
have supplemental information about the likelihood of threat occurrence, this approach is
preferable. Although the SEA WAT analysis considered impacts to sustainable basin yield, the
likelihood of the specified threats at each time period was not examined in detail.
2.1.2 Time Periods
A total of five time periods can be selected in a GREAT analysis. Time period selection is
flexible, allowing users to choose time periods for a variety of reasons, such as to coincide with
existing asset management cycles, capital/infrastructure planning cycles, or projected timing of
climate change impacts. Workgroup participants agreed that the time periods "2050" and "2100"
were appropriate for the Morro Bay GREAT analysis. These time periods were chosen to match
the years used in the SLR projections calculated by the State of California's Ocean
Protection Council (OPC).4 In 2010, the OPC developed a SLR guidance document and
selected the planning timeframes of 2050 and 2100. The OPC SLR projections indicate
a rise of 16 inches by 2050 and 55 inches by 2100.
2.1.3 Consequence Weighting
GREAT allows users to assess consequences from climate change across five selected categories.
The categories listed in Table 1 are provided to ensure that the analysis considers a range of
losses throughout the watershed due to climate change.
Table 1. Consequence Evaluation Categories
Consequence Evaluation Categories
Business Impacts
Equipment/facility Impacts
Source/receiving water Impacts
Environmental Impacts
Community Impacts
Definition
Revenue or operating income loss evaluated in terms of the
magnitude and recurrence of service interruptions.
Costs of replacing the service equivalent provided by a facility
or piece of equipment evaluated in terms of the magnitude of
damage and financial impacts.
Degradation or loss of source water or receiving water quality
and/or quantity evaluated in terms of the recurrence.
Evaluated in terms of environmental/ecosystem damage or
loss and compliance with environmental regulations
Public health impacts evaluated in terms of the duration and
extent.
There was discussion among workgroup participants regarding the "Consequence Weighting"
function in GREAT's setup step. The Morro Bay workgroup chose to use the "WEIGHTED
4For more information about SLR guidance from the OPC, please reference the Sea Level Rise Task Force
Interim Guidance document at: http://www.opc.ca.gov/2011/07/sea-level-rise-task-force-interim-guidance-
document/.
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SUM" method to aggregate the categories above based on relative weights. Weighting values of
20 percent were distributed evenly across the above categories. The workgroup inquired about
the definition of the Business Impacts category and whether the value for that category should be
decreased as there are not many businesses/industry entities in the area. It was clarified that the
Business Impacts category refers to the utility's ability to carry on business as usual and realize
their typical revenue. For more complete definitions of each category, see Table 1.
Later in the GREAT process, some workgroup participants expressed concerns about the default
definition associated with the Community Impacts category, noting that this definition differed
from their perceived definition of "Community Impacts". More specifically, participants stated
that the Community Impacts category definition seemed limited to public health. The workgroup
noted that this category may include more than just impacts related to public health. For
example, economic development considerations could also fall within this category.
Additionally, the workgroup recommended that perhaps future versions of the GREAT software
could be designed with more flexibility such that definitions for consequence evaluation
categories could be changed by the user. Following the Morro Bay exercise, this suggestion was
implemented in GREAT version 2.0, allowing users the flexibility to edit consequence evaluation
categories.
The workgroup agreed that the following statement should be included in this report.
"While "community impacts" in this context is limited to public health, the Los Osos
Water Purveyors acknowledge that the overall community impacts associated with these
threats: degraded water quality from saltwater intrusion and r educed groundwater
recharge from drought, including socio-economic impacts, are very high. "
Image 3. Morro Bay National Estuary
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2.2 CREAT and Cal-Adapt Climate Data for the SEAWAT Analysis
During Webinar 1 of this exercise, workgroup participants discussed the methodology used to
define temperature and precipitation data in the SEAWAT analysis. In an effort to identify the
most appropriate inputs for the SEAWAT analysis, a subgroup considered both the CREAT and
Cal-Adapt5 climate datasets. CREAT provides projected temperature and precipitation values
based on 112 model runs using 16 different general circulation models (GCMs) and three
emission scenarios (TPCC SRES A2, A1B, and Bl). CREAT also uses statistically downscaled
GCM projections from the World Climate Research Programme (WCRP) Coupled Model
Intercomparison Project, Phase 3.6 These projections present a range of model results for two
30-year time periods, mid-and late-century, defined by the lowest and the highest average model
run result.
Climate data from the Cal-Adapt website offers a view of how climate change might affect
California at the local level. As such, results from the four Cal-Adapt models were reviewed by
subgroup participants. Among the four Cal-Adapt models reviewed by the subgroup, projected
conditions from one model, the Centre National de Recherches Meteorologiques (CNRM)
model, was compared to the CREAT averages for each calendar month during the mid-and late-
century time periods. Results from the CNRM model were selected, as CNRM seemed to
provide the lowest overall precipitation projections, which were considered as worst-case
scenarios for increased saltwater intrusion and reductions to basin yield during the SEAWAT
analysis.
The Morro Bay Fire Department station provided the baseline temperature and precipitation data
for the SEAWAT analysis. Monthly averages for current/baseline conditions, mid-century, and
late-century precipitation and temperature were extracted from the CNRM model for the Morro
Bay area. The percent change between the baseline conditions and projected time periods for
each emissions scenario was applied to the average monthly precipitation and temperature at the
Morro Bay Fire Department (1981-2010), with slight adjustments made to match the average
annual percent change. Mid-century precipitation projections, which represent an average over
the 30-year period, show the driest conditions of 11.8 inches annually. Late century precipitation
projections illustrate an approximate average of 14.7 inches annually, compared to the historical
baseline average of 17.5 inches.
For additional information about the projected temperature and precipitation values used in the
SEAWAT analysis, see Appendix B, and for a more detailed comparison of monthly data from
CREAT and Cal-Adapt, see Appendix C.
5 The California Energy Commission has funded and directed the development of Cal-Adapt, a website that
synthesizes existing California climate change scenarios for decision-makers.
6
World Climate Research Programme (WCRP). 2008. Coupled Model Intercomparison Project, Phase 3 (CMIP3)
multi-model dataset.
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2.3 SLR Proj ections - California
Following the first webinar, workgroup participants were provided with the State of California's
OPC guidance document, which provides guidelines for incorporating SLR projections
into planning and decision making for projects in California. This document recommends using
16 inches (41 cm) as the SLR estimate for 2050, and 55 inches (140 cm) of SLR
or 2100.
2.4 Prioritizing Assets and Threats for the Analysis
GREAT users have an opportunity to analyze each vulnerable asset and climate change threat at
specific time periods. Within GREAT, users can select vulnerable assets from two categories:
natural resources and infrastructure. For example, the Morro Bay National Estuary would be a
"natural resource" asset, while specific wells would be considered an "infrastructure" asset.
Threats related to climate change are also considered in respect to the potentially impacted asset.
Together, GREAT refers to this combination as a user's "asset-threat pair".
During the GREAT analysis, the Morro Bay workgroup realized that they could not analyze all
vulnerable assets in the watershed. The term "prioritized" refers to the specific assets selected
for this analysis. A list of Morro Bay's "prioritized" assets and corresponding climate change
threats can be found in Table 2.
In addition, the Morro Bay workgroup initially discussed identifying each of the Los Osos wells
as separate assets. However, this becomes an issue of "double counting" - meaning that the
threats to the individual wells will already be considered during the analysis of the upper and
lower aquifers. Instead of listing the wells separately, the GREAT analysis file includes the
wells based on their geographic location in specific zones of the aquifer. For example, the
Golden State Water Company Skyline well is included within the Los Osos Upper Aquifer asset.
Table 2. Prioritized Assets and Threats at 2050 and 2100
Asset
Los Osos Creek
Warden Creek
Willow Creek
Morro Bay Estuary
Los Osos Upper Aquifer
Los Osos Lower Aquifer
Morro Bay Estuary
Los Osos Upper Aquifer
Los Osos Lower Aquifer
Threat
Reduced groundwater recharge from drought
Reduced groundwater recharge from drought
Reduced groundwater recharge from drought
Reduced groundwater recharge from drought
Reduced groundwater recharge from drought
Reduced groundwater recharge from drought
Degraded water quality from saltwater intrusion
Degraded water quality from saltwater intrusion
Degraded water quality from saltwater intrusion
2.5 Existing and Potential Adaptive Measures
The Morro Bay workgroup agreed that the following existing adaptive measures were already in
place at one or more water utilities throughout the Los Osos Basin. Within Morro Bay's GREAT
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analysis, the measures below are listed as existing adaptive measures for all asset-threat pairs at
the 2050 and 2100 time periods.
Effluent re-use studies
Nutrient/contaminant models
Water quality models
Monitoring temperature
Monitoring treatment or system
Monitoring water quality
Monitoring weather
Current demand reduction/conservation programs
Rate structure changes
2.6 Using CREAT and SEAWAT Together
GREAT provided a framework to bring Morro Bay's watershed stakeholders together to explore
an expanded scope of risk management and planning for Morro Bay's drinking water utilities.
The adaptive measures used in the SEAWAT model include the proposed wastewater project and
associated water reinvestment program, urban water use efficiency program/water conservation
and a basin infrastructure program. CREAT refers to future adaptive measures, aimed at
increasing resilience, as potential adaptive measures. As part of the Resilience Analysis in
CREAT, users select potential adaptive measures aimed at reducing vulnerabilities associated
with the specified threats. In the SEAWAT analysis these potential adaptive measures are
considered during certain model runs using the term "management scenario". Table 3
crosswalks these adaptive measures to those listed in the CREAT analysis.
SEAWAT provided groundwater safe yield estimates by incorporating historical and projected
climate data and assuming the implementation of a set of potential adaptive measures during the
management scenario model runs. Both CREAT and SEAWAT are valuable to Morro Bay's
watershed stakeholders. With a better understanding of projected safe yield estimates for mid-
(2050) and late-century (2100), stakeholders can begin and continue discussions about the most
optimal climate change adaptation strategies to further the goals of the Los Osos Groundwater
Basin Management Plan. Although SEAWAT model results are not direct inputs into the
CREAT framework, the scientific context that these results provided was extremely valuable to
workgroup decisions during the CREAT analysis steps.
Table 3. Potential Adaptive Measures
SEAWAT
Management Scenario
Wastewater Project
Urban Water Use
Efficiency Program
CREAT Adaptive
Measure Category
Sustainable Strategies
Users/Demand
Potential Adaptive Measure
Description
Effluent re-use (e.g., water treatment
through the reuse of treated
wastewater)
Groundwater
augmentation/reinvestment
Additional demand reduction
programs
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Basin Infrastructure
Program
Repair/Retrofit
Construct
Altered Treatment (e.g., utilize
blending stations/nitrate removal
treatment to treat water for
potability)
Interconnections with other water
systems
General - new asset
(e.g., relocation and/or development
of a new treatment; changes to
pumping schedule to adapt to
saltwater intrusion)
2.6.1 SEAWAT Analysis
The SEA WAT program was developed to simulate three-dimensional, variable-density, transient
groundwater flow in porous media. SEAW AT combines MODFLOW (modular flow) and
MT3D (mass transport) code, and adds variable fluid density capability for saltwater intrusion
simulations. For this project, a total of 14 basin model scenarios were defined, based on
combinations of SLR, global warming and changes in precipitation, with and without
adaptive measures. Section 2.6.2 summarizes results from the SEAW AT model runs.
2.6.2 SEAW AT Results Summary
Baseline Scenario
Under baseline conditions with no wastewater project, no adaptive measures, and no climate
change, the sustainable yield of the groundwater basin with existing operational wells is
estimated to be 2,455 acre-feet per year (AFY). Climate change reduces the baseline yield by 75
AFY due to late-century SLR7, by 125 AFY due to increased average temperature, and
up to an additional 450 AFY due to potential declines in precipitation - illustrating a total
potential decline up to 650 AFY, resulting in 1,805 AFY basin yield).
Management Scenario with Adaptive Measures
With the planned wastewater project and adaptive measures in place during the management
scenario model runs, basin yield with no climate change increases to 3,400 AFY. Climate
change reduces this projected basin yield by 100 AFY due to late-century SLR, by 125
AFY due to increased average temperature, and up to an additional 850 AFY due to potential
declines in precipitation - illustrating a total potential decline of up to 1,075 AFY, resulting in
2,325 AFY basin yield.
When comparing management scenarios to the corresponding baseline scenarios, the wastewater
project and adaptive measures increase the basin yield by 520 AFY to 945 AFY, depending on
A stand-alone mid-century SLR scenario was not one of the 14 scenarios analyzed during this analysis.
For more detailed information, see Appendix B.
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the scenario. The leading edge of the saltwater intrusion front in the lower aquifer, as defined by
the 250 milligram per liter (mg/1) isochlor, advances into the central basin area under sustainable
yield scenarios. If the maximum yield of a baseline scenario is simulated with the wastewater
project and adaptive measures in place, the saltwater intrusion front withdraws from the central
basin area and retreats to the eastern boundary of the dunes and bay area. For more specific
information about the SEA WAT methodology and model results, see Appendix B.
2.7 Baseline and Resilience Analysis Discussion
CREAT's Baseline Analysis establishes a benchmark for the level of risk that threats associated
with climate change may pose to utility assets.8 The results of the Baseline Analysis, which is an
examination of climate change threats with existing adaptive measures, describe the current
consequence levels from risk to assets due to the occurrence of future climate-related threats.
The Resilience Analysis is basically the same process as the Baseline Analysis, except that asset-
threat pairs are analyzed while considering potential adaptive measures that can be implemented
at 2050 and 2100.
The Morro Bay workgroup considered how to protect Morro Bay's assets from climate-related
threats by highlighting existing adaptive measures during the Baseline Analysis and discussed
the implementation of additional adaptive measures during the Resilience Analysis (Table 3). At
the end of the analyses steps, the results for these selections are added to allow for a
comprehensive assessment of assets, threats, and resiliency.
2.7.1 Re-Assessing Consequence Levels
During the Resilience Analysis, GREAT users reassess and select one of the following
consequence levels: "Very High", "High", "Medium", or "Low". These consequence levels
must be selected in each of the five consequence evaluation categories for each asset-threat pair.
The change in consequence level between the Baseline and Resilience Analyses, following the
implementation of potential adaptive measures, contributes to the relative change in risk
reduction provided for each asset-threat pair. Figure 1 illustrates a description of the
consequence level category for Environmental Impacts.
' Table 2 provides a complete list of assets and threats.
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Environmental
Impacts
Very High
High
Medium
Low
Description
Significant environmental
damage- may incur regulatory
action
Persistent environmental
damage- may incur regulatory
action
Short-term environmental
damage, compliance can be
quickly restored
No impact or environmental
damage
Figure 1. Example of Consequence Level Description - Environmental Impacts
Following the webinars, extensive discussions took place regarding the change in consequence
levels assigned to Morro Bay's asset-threat pairs. Some workgroup members were concerned
with the following issues related to the adaptive measures selected during the GREAT analysis
and the ability of those measures to contribute to the environmental sustainability of some of
Morro Bay's natural assets or to meet future community water demand.
Issue 1: The SEA WAT results indicate that Los Osos Creek will contribute more
recharge to the aquifers/wells after the potential adaptive measures are implemented.
This may result in greater yield for the Los Osos basin. This may also result in less
average surface flow in Los Osos Creek, potentially impacting stream flow and habitat
ecology. The mitigation for these potential impacts will likely involve water reuse for
agriculture in the Los Osos Creek valley.
Issue 2: The adaptive measures will significantly increase basin yield compared to
baseline conditions with climate change, meaning that the adaptive measures could offset
the impacts of climate change. However, basin yield may be insufficient to meet future
buildout demand due to climate change impacts, such as saltwater intrusion and reduced
groundwater recharge.
Some workgroup members noted that even following the implantation of potential adaptive
measures, environmental impacts would still remain high for certain asset-threat pairs.
Workgroup members were most concerned with saltwater intrusion and reduced recharge in the
Morro Bay Estuary, and reduced recharge in Los Osos, Willow and Warden Creeks. Even
considering the implementation of potential adaptive measures at 2050 and 2100, workgroup
members chose to keep the Environmental Impacts' consequence level "Very High" for the
above mentioned asset-threat pairs.
Following the webinars, workgroup comments were addressed and changes to the consequence
levels in Morro Bay's GREAT analysis file were made to reflect the above concerns. For more
detailed information about changes made to the consequence levels in the Baseline and
Resilience Analysis steps in response to the above issues, see Appendix D.
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2.7.2 Adaptive Measure Contribution
As part of the Resilience Analysis in GREAT, users select potential adaptive measures aimed at
further reducing vulnerabilities from specified threats. This step allows GREAT users to allocate
the relative contributions of selected adaptive measures to overall consequence reduction for an
asset-threat pair. While precise quantification may be impossible, it is reasonable and
informative to provide high-level estimates.
Following the fourth webinar, members of the Morro Bay workgroup commented on the
adaptive measure contribution values and assigned varying percentages to each of the selected
potential adaptive measures. The adaptive measure contribution inputs were discussed among a
subgroup, and these inputs can be revised in Morro Bay's GREAT analysis file in the future.
For more information about the specific adaptive measure contribution values assigned by the
Morro Bay workgroup, see Table 4.
Table 4. Adaptive Measure Contribution
Potential Adaptive Measure
Effluent re-use
Altered treatment (e.g., utilize blending stations/
nitrate removal)
General new asset (e.g., relocation and/or new treatment
facility)
Los Osos Interconnections
Additional Water Conservation Programs
Additional Adaptive Rate Structures
Groundwater Augmentation/Reinvestment
Total Contribution
Adaptive
Measure
Contribution (%)
7
5
41
5
16
9
17
100
2.7.3 Examining Risk Reduction - Resilience Analysis
GREAT provides a way to compare current and future risk as it relates to threats posed by a
changing climate. In GREAT, the reduction of risk can be visualized in a risk matrix (Figure 2),
where each asset-threat pair analysis falls into a specific combination of likelihood of threat
occurrence and level of consequence. This matrix considers both the user-defined reduction in
consequence levels from the Baseline to Resilience Analysis and the attribution percentage value
given to each selected potential adaptive measure. Risk matrices in Figure 2 also show the
number of asset-threat pairs for each likelihood-consequence combination for all Baseline (top
row) and Resilience (bottom row) analyses. For example, in Morro Bay's GREAT analysis all
nine asset-threat pairs have a very high likelihood of occurrence, but their consequence level is
reduced to low and medium during the Resilience Analysis after considering the implementation
of additional adaptive measures.
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Climate Ready Water Utilities - Climate Ready Estuaries
GREAT Exercise Report
Baseline
Resilience
0000
oooo
0000
low Mutium With Wry
Figure 2. Morro Bay Risk Matrices
2.8 Implementation Planning - Adaptation Packages
Selecting potential adaptive measures in GREAT does not imply that these measures will resolve
all impacts related to climate change in Los Osos Basin. Rather, GREAT offered the Morro Bay
workgroup a comparative framework to analyze the risk reduction of consequences associated
with existing and potential adaptive measures.
During GREAT's Implementation Planning step, users can build "adaptation packages" that
include adaptive measures and user-defined estimated costs of each package. After adaptation
packages are created, a significant amount of time is needed for the discussion of relative risk
reduction and associated costs of each adaptation package. Example adaptation packages were
developed for the Morro Bay GREAT exercise to illustrate which adaptive measures, if
implemented, could potentially offer the highest level of risk reduction from specified climate
change threats. GREAT's adaptation packages allow users to create reports and compare risk
reduction units (RRUs) and estimated costs associated with the implementation of selected
adaptive measures. RRUs within GREAT provide a metric for users to compare packages. The
change in consequence level from the Baseline Analysis to the Resilience Analysis is used to
calculate RRUs for each asset-threat-time period combination. For example, if the consequences
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Climate Ready Water Utilities - Climate Ready Estuaries
GREAT Exercise Report
for an asset with a "very high" likelihood threat change from Very High (Baseline) to Medium
(Resilience), then the RRUs are calculated as 100 - 60 = 40 RRUs (circled locations in Figure 3)
4B 3B 2B
(40) (45) (55)
40 3D 2D
35) (37) (40)
Low Medium High Very
High
Consequences
Figure 3. Matrix Used to Calculate Risk Reduction Units (RRUs)
Table 5 provides an example adaptation package for Morro Bay, illustrating the RRUs associated
with each adaptive measure at 2050 and 2100. The RRUs are 137.7 at each time period,
assuming that the potential adaptive measure will be implemented or improved at both 2050 and
2100. GREAT calculates RRUs for each asset-threat pair by taking the value of reduction in
consequences (Figure 3) combined with the individual adaptive measure contribution percentage.
GREAT users can compare total RRUs for each adaptation package to support the
implementation of specific adaptation packages during decision making processes.
Table 5. Example Adaptation Package for Morro Bay - "Basin Infrastructure Plan'
Potential Adaptive Measures Included
General new asset - E.g., Relocation and/or
development of a new treatment facility; Changes
to pumping regimes
Los Osos Interconnections
Altered treatment - E.g., Utilize blending
stations/nitrate removal treatment to treat water
for potability
Total Package RRUs
RRUs
at 2050
110.7
13.5
13.5
137.7
RRUs
at 2100
110.7
13.5
13.5
137.7
Total
Package
RRUs
221.4
27
27
275.4
No financial cost estimates were included in Morro Bay's adaptation packages. There was
reluctance on the part of workgroup participants to apply costs to adaptive measures due to the
uncertainty associated with projected climate change impacts and potential public reaction.
However, estimated cost information can be added to the analysis file in the future by the Morro
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Climate Ready Water Utilities - Climate Ready Estuaries
GREAT Exercise Report
Bay workgroup. Once cost estimates are entered into the GREAT file, Morro Bay watershed
stakeholders can assemble a more descriptive adaptation package that illustrates costs related to
implementing adaptive measures in comparison with the risk reduction associated with those
measures. Since adaptation packages were not finalized during the GREAT exercise, the
workgroup can consider the implementation of specific adaptive measures and continue to refine
adaptation packages in the GREAT analysis file at a later date.
2.9 Results and Reports
The Results & Reports feature in GREAT includes a variety of ways to visually illustrate relative
risk reduction after considering the implementation of potential adaptive measures. This risk
reduction can be seen in the bar graphs on the Results Summary tab, as illustrated in Figure 4.
Members of the workgroup noted that the bar graphs in the Results Summary step are good
illustrations of risk reduction and will be relevant and helpful to the Los Osos Water Purveyors,
as these graphs offer a concise way to illustrate the risk reduction associated with implementing
adaptive measures.
* Results Summary
The Results Summary is a high-lev el overview of the analysis performed by GREAT The total 5 for Likelihood of Threat and Co nsequences for both the
Baseline and Resilience Analysis are shown Use the Time Period Drill-Down to explore the data
Baseline Consequence Risk Profile
Resilience Consequence Risk Profile
1
I-
tte
i i i
2035 2060
i*" All Adaptive Measure
Number of Threats Evaluated by Time Period
(with Consequence Risk Profile)
Selected Adaptation Package JAII potential adaptive measures ^
Number of Adaptive Measures Evaluated hy Time Period
iHExistins Hpatantiall
H 1 1 H
Figure 4. Example Results Summary Tab
Risk matrices are also displayed in GREAT's Results and Reports step. GREAT assesses risk
based on the likelihood of occurrence and overall reduction in consequences. Figure 2 depicts
these matrices and shows Morro Bay's nine asset-threat pairs for each likelihood-consequence
combination for all Baseline Analyses (top boxes) and Resilience Analyses (bottom boxes) at the
2050 and 2100 time periods. This approach assumes a very high likelihood of occurrence for all
asset-threat pairs. This concept is illustrated in Figure 2, as all asset-threat pairs remain in the
top row of the matrices. The implementation of potential adaptive measures during the
Resilience Analysis can lower the consequences for each asset-threat pair. This is illustrated in
Figure 2, as all nine asset-threat pairs move left into the "low" and "medium" columns to
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Climate Ready Water Utilities - Climate Ready Estuaries GREAT Exercise Report
indicate lower consequences. The results from this GREAT analysis are preliminary and warrant
further discussion and evaluation among stakeholders.
3. Lessons Learned and Conclusions
The CRWU-CRE Joint GREAT Exercise in Morro Bay demonstrated a method for augmenting
the information used in the GREAT risk assessment and planning process by considering the
results of a numerical model, SEA WAT.
3.1 Future Use of CREAT and SEA WAT in Morro Bay
The final CREAT analysis file can be edited and used in the future as new information becomes
available. The process of risk assessment is iterative - meaning that Morro Bay watershed
stakeholders should continually examine their vulnerable assets, projected climate change
threats, and adaptive measures to adequately protect their natural resources and built
infrastructure from future climate change impacts. Additionally, the discussions regarding
Morro Bay's CREAT inputs and information from this report can inform future water resource
management efforts in Los Osos Basin and perhaps be used to supplement and refine the Los
Osos Groundwater Basin Management Plan.
The SEA WAT model results were used to inform the Los Osos Groundwater Basin Management
Plan. This Plan intends to help the Los Osos Water Purveyors develop a strategy to identify safe
yield for water resources, prevent saltwater intrusion, prevent watershed contamination, identify
water conservation programs and protect the environment.
3.2 Feedback from Participants and Next Steps
At the conclusion of the fourth and final webinar, Morro Bay workgroup participants were asked
about the effectiveness of using CREAT to bring together watershed partners, and for
suggestions to improve future planning efforts. One participant inquired if the CREAT 1.0
analysis files could be used with CREAT 2.0. It was noted that CREAT 1.0 files, used in the
Morro Bay analysis, will be compatible with version 2.0 with minor modifications by the user.
CREAT 2.0 includes support for multiple locations, quantitative information on extreme
precipitation events, the ability to document the energy implications of adaptation, and improved
support for scenario-based planning. Workgroup participants also noted that engaging in
CREAT's risk assessment process may help them when applying for various grants to fund the
implementation of adaptive measures. Other participants believed that having the results from
the SEAWAT analysis to inform the CREAT process added value for Morro Bay stakeholders.
Morro Bay NEP and others in Morro Bay noted that they hope to continue to foster their
relationships with EPA and each other in the future.
3.3. Conclusion
While the webinars were valuable in demonstrating the functionality of CREAT and obtaining
feedback from the workgroup on major inputs to CREAT and SEAWAT, some of the
illuminating discussions took place outside of the formal meetings and following the fourth
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Climate Ready Water Utilities - Climate Ready Estuaries GREAT Exercise Report
webinar. More specifically, the selection of the adaptive measures in the GREAT file was
initially limited to those measures applicable to achieving safe yield (water supply) in Los Osos
Basin while addressing impacts from saltwater intrusion and reduced groundwater recharge.
Following the fourth webinar, feedback from members of the workgroup illustrated that some
adaptive measures that intend to reduce risk from saltwater intrusion and reduced groundwater
recharge may actually adversely impact Morro Bay's environment through impacts such as
reducing base flow to watershed streams. Participants noted that these impacts could be
mitigated through the implementation of additional adaptive measures. This conclusion warrants
further discussion among Morro Bay watershed stakeholders.
19
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Appendix A
Participants List
Joint CREAT Exercise for Morro Bay
EPA
Curt Baranowski, Office of Water (OW)
Nancy Laurson, OW
Suzanne Marr, EPA Region 9
John Whitler, OW
EPA Oak Ridge Institute for Science and Education (PRISE) Fellows
Laura Dubin
Amy Posner
Morro Bay NEP
Adrienne Grevy, California Polytechnic State University
Jon Hall, Morro Bay NEP
Adrienne Harris, Morro Bay NEP
Dave Paradies, Morro Bay Foundation
Morro Bay Water Stakeholders
Don Asquith, S&T Mutual Water Company
Bob Collar, Golden State Water
Courtney Davis, Brownstein Hyatt Farber & Schreck
Ray Dienzo, San Luis Obispo County
Frank Freiler, S&T Mutual Water Company
Dan Gilmore, Ernest Gisler, Golden State Water Company
Los Osos Community Services District (CSD)
Spencer Harris, death-Harris Geologists
Tim McNulty, Counsel's Office, St. Luis Obispo County
Toby Moore, Golden State Water
Rob Miller, Wallace Group
Ken Peterson, Golden State Water
John Seitz, Shipsey and Seitz
Wes Strickland, Brownstein Hyatt Farber & Schreck
Dave Tolley, S&T Mutual Water Company
Patrick Vowell, Golden State Water
John Waddell, San Luis Obispo County
Mark Zimmer, Golden State Water
This list includes individuals that participated in the project at various times from January-September
2012.
-------
Appendix B
TECHNICAL MEMORANDUM
Date: December 10, 2012
From: Spencer Harris
To: Los Osos ISJ / Morro Bay NEP
SUBJECT: Model Results for Los Osos Climate Ready Water Utilities Project.
This memorandum presents the results of groundwater model scenarios selected for evaluating
the sustainable yield of the Los Osos Valley Groundwater Basin under projected climate change
conditions. These scenarios have been developed as part of the Climate Ready Water Utilities
Project.
Model Results Summary
Under baseline conditions (no wastewater project, no adaptive measures, no climate
change), the sustainable yield of the groundwater basin with existing operational wells is
estimated to be 2,455 acre-feet per year (AFY). Climate change reduces the baseline
yield by 75 AFY due to late-century SLR, by an additional 125 AFY with
increased average temperature, and up to an additional 450 AFY with potential declines
in precipitation (total potential decline up to 650 AFY; 1,805 AFY basin yield).
With the wastewater project and adaptive measures in place (management scenarios),
basin yield with no climate change increases to 3,400 AFY. Climate change reduces this
projected basin yield by 100 AFY due to late-century SLR, by an additional 125
AFY with increased average temperature, and up to an additional 850 AFY with potential
declines in precipitation (total decline up to 1,075 AFY; 2,325 AFY basin yield).
When comparing management scenarios to the corresponding baseline scenarios, the
wastewater project and adaptive measures increase the basin yield by 520 AFY to 945
AFY, depending on the scenario.
The leading edge of the seawater intrusion front in the lower aquifer, as defined by the
250 milligram per liter (mg/1) isochlor, advances into the central basin area under
sustainable yield scenarios. If the maximum yield of a baseline scenario is simulated with
the wastewater project and adaptive measures in place, the seawater intrusion front
withdraws from the central basin area and retreats to the eastern boundary of the dunes
and bay area.
Appendix B - SEAWAT RESULTS 1 December 10, 2012
-------
Appendix B
Climate Change Scenario Definition
Climate change projections for mid-century and late-century conditions were used to evaluate
impacts on seawater intrusion in the Los Osos groundwater basin. SLR projections are
provided in the October 2010 State of California Sea-Level Rise Interim Document
(http://www.opc.ca.gov). At mid-century, 16 inches of SLR is assumed for impacts
evaluation. At late-century, 55 inches of rise is assumed.
Projections of changes in precipitation and temperature have been derived from the results of
global circulation models for Intergovernmental Panel on Climate Change (IPCC) Scenario A2
(medium high emissions) and Scenario Bl (lower emissions). The California Energy
Commission has funded and directed the development of Cal-Adapt, a website that synthesizes
existing California climate change scenarios for local decision-makers.
(http://www.cal -adapt, org)
Cal-Adapt provides IPCC emission scenario results from four global circulation models to
characterize climate change projections in California. These four models are a subset of the 16
models contained in the EPA Climate Resilience Evaluation and Awareness Tool (GREAT). A
comparison of model run results provided by GREAT and Cal-Adapt indicates that the majority
of Cal-Adapt model results for precipitation are in the lower portion of the GREAT range.
Among the four Cal-Adapt models, the Centre National de Recherches Meteorologiques
(CNRM) model provided the lowest overall precipitation projections, which would be considered
worst-case for seawater intrusion impacts analysis. For consistency, the output for the CNRM
model was used to derive both precipitation and temperature climate change projections.
CNRM and GREAT current condition baselines describe slightly different seasonal patterns due
to different sources (model versus observations). The GREAT baseline more closely matches the
Morro Bay Fire Department historical records, and was used for model comparisons and for
applying CNRM climate projections locally.
Monthly averages for mid-century and late-century precipitation and temperature were extracted
from the CNRM model for the Morro Bay area. The change between the current condition
GREAT baseline and projected time periods for each emission scenario was applied to the
average monthly precipitation and temperature at the Morro Bay Fire Department (1981-2010).
Table 1 and Table 2 summarize the precipitation and temperature projections for use in
evaluating seawater intrusion impacts.
Appendix B - SEAWAT RESULTS 2 December 10, 2012
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Appendix B
CHG
Table 1
Precipitation and Temperature Projections
IPCC Scenario A2
Month
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Annual
Baseline (198 1-20 10)
Precip.
(inches)
3.57
3.77
3.29
1.1
0.43
0.08
0.01
0.05
0.24
0.82
1.4
2.72
17.48
Temp.
(°F)
54.8
55.9
56.8
57.2
57.9
59.7
61.6
62.3
62.5
61.8
58.8
54.6
58.7
Mid-Century
Precip.
(inches)
2.70
2.76
1.12
0.54
0.27
0.04
0.03
0.03
0.62
0.76
0.80
2.14
11.82
Temp.
(°F)
55.4
56.5
57.4
57.8
58.9
60.9
63.1
64.1
64.4
63.4
60.1
55.3
59.8
Late-Century
Precip.
(inches)
3.33
3.50
1.07
0.35
0.08
0.06
0.03
0.28
1.41
0.80
1.21
2.58
14.70
Temp.
(°F)
58
58.9
59.9
60.2
61.1
63
65.9
67.3
67.7
66.3
62.7
57.5
62.4
Appendix B - SEAWAT RESULTS
December 10, 2012
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Appendix B
CHG
Table 2
Precipitation and Temperature Projections
IPCC Scenario Bl
Month
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Annual
Baseline (198 1-20 10)
Precip.
(inches)
3.57
3.77
3.29
1.1
0.43
0.08
0.01
0.05
0.24
0.82
1.4
2.72
17.48
Temp.
(°F)
54.8
55.9
56.8
57.2
57.9
59.7
61.6
62.3
62.5
61.8
58.8
54.6
58.7
Mid-Century
Precip.
(inches)
3.00
5.43
2.52
0.95
0.27
0.06
0.03
0.25
0.76
0.91
1.19
2.71
18.09
Temp.
(°F)
56.1
57.1
58.0
57.9
58.9
60.8
63.1
64.4
64.5
63.5
60.2
56.0
60.1
Late-Century
Precip.
(inches)
3.05
3.36
1.07
0.57
0.16
0.06
0.02
0.19
0.63
1.01
1.31
2.60
14.02
Temp.
(°F)
56.1
57.1
58.4
58.8
58.9
61.1
63.7
64.9
65.0
64.3
60.8
56.3
60.5
Model Scenario Definition
The Los Osos basin model utilizes the U.S. Geological Survey's SEAWAT program, which was
developed to simulate three-dimensional, variable-density, transient groundwater flow in porous
media. SEAWAT combines MODFLOW (modular flow) and MT3D (mass transport) code, and
adds variable fluid density capability for seawater intrusion simulations.
A total of fourteen basin model scenarios have been defined, based on combinations of sea level
rise, increased average air temperatures, and changes in precipitation, with and without adaptive
measures. Brief descriptions of the scenarios are presented in Table 3 below.
Appendix B - SEAWAT RESULTS
December 10, 2012
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Appendix B
CHG
Table 3
Basin Model Scenarios
Model Scenario
Baseline Scenarios:
No wastewater project
No adaptive measures
Purveyor facilities operating
as of December 3 1, 201 1
Management Scenarios:
Wastewater project
Water reinvestment program
Urban water use efficiency
program
Basin infrastructure program
Scenario ID
NCb
SL55b
WSL55b
MA2b
LA2b
MBlb
LBlb
NCm
SL55m
WSL55m
MA2m
LA2m
MB 1m
LBlm
Description
No Climate Change
55 inches SLR
55 inches SLR with warming
16 inches SLR with warming and
CNRM mid-century A2 precipitation
55 inches SLR with warming and
CNRM late-century A2 precipitation
16 inches SLR with warming and
CNRM mid-century Bl precipitation
55 inches SLR with warming and
CNRM late-century Bl precipitation
No Climate Change
55 inches SLR
55 inches SLR with warming
16 inches SLR with warming and
CNRM mid-century A2 precipitation
55 inches SLR with warming and
CNRM late-century A2 precipitation
16 inches SLR with warming and
CNRM mid-century Bl precipitation
55 inches SLR with warming and
CNRM late-century Bl precipitation
Adaptive Measures
The adaptive measures selected for analysis using the SEAWAT basin model include the
wastewater project and associated water reinvestment program, an urban water use efficiency
program (water conservation), and a basin infrastructure program. Table 4 relates these adaptive
measures to a few of those listed in the GREAT tool.
Appendix B - SEAWAT RESULTS
December 10, 2012
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Appendix B
CHG
Table 4
Adaptive Measures
Management Scenario Measure
Wastewater Project
Urban Water Use Efficiency
Program
Basin Infrastructure Program
GREAT Adaptive Measure
Sustainable Strategies
Users/Demand
Repair/Retrofit
Construct
Description
Effluent re-use
Groundwater recharge
Demand reduction
Altered Treatment
General-New Asset
Interconnections
Changes in the basin model related to the wastewater project include collection of septic return
flows and redistribution of wastewater discharges and related return flows. The Urban Water Use
Efficiency Program will lower urban indoor water demand, and will shift the ratio of indoor to
outdoor water use, which adjusts return flows in the basin model. The basin infrastructure
program includes constructing water treatment/blending facilities, new wells, pipeline upgrades
and purveyor system interconnections.
Basin Recharge Adjustments
Sea level increases for mid-century and late-century conditions are input directly into the basin
model. The other two climate change projections, precipitation and temperature, affect basin
recharge.
Components of fresh water recharge to the basin include direct percolation of precipitation,
capture of runoff within the basin, seepage from Los Osos Creek, subsurface inflow from
bedrock, and return flows from irrigation and septic systems. Changes in basin recharge due to
climate change have been adjusted using a soil moisture budget and runoff equation with revised
reference evapotranspiration (ETo) and precipitation values. Return flows from outdoor urban
area water use are based on the purveyor yield values and the ratio of indoor to outdoor water use
for each scenario.
Evapotranspiration
Climate change projections for the Morro Bay area from the CNRM model include warming and
reduced precipitation (Tables 1 and 2), both of which would increase the local ETo. The Los
Appendix B - SEAWAT RESULTS
December 10, 2012
-------
Appendix B
CHG
Osos Valley groundwater basin has a significant coastal fog gradient. Basin area ETo is
estimated at 40.5 inches per year based on averaging data from coastal California Irrigation
Management Information System (CIMIS) stations in Monterey and Santa Barbara Counties.
With climate change, the range of projected mean annual temperature and precipitation for
Morro Bay will be comparable to current conditions along the south coast of California, based on
a review of mean temperature and average annual precipitation maps. ETo for mid- and late-
century climate change projections are estimated at 46 inches per year, with monthly ETo
distribution corresponding to CIMIS Climate Zone 4 (reference evapotranspiration map available
at http://wwwcimis.water.ca.gov/cimis/images/etomap.jpg).
Soil Moisture Budget
Nine classifications of land use with corresponding crop coefficients and rooting depths were
used to develop 43 geographic zones representing different combinations of land use across the
basin during model development in 2003. A daily soil moisture budget was originally
constructed for estimating deep percolation of precipitation through each of the geographic
zones. For the climate change scenarios, the soil moisture budget was reconstructed for monthly
time-steps and used to update the recharge estimates for each geographic area based on the
projected monthly ETo and CNRM precipitation values. The runoff equation was also
recalibrated to reduce the potential capture of runoff within the basin based on higher
temperatures and lower precipitation.
Model Results
The results of basin model scenarios are reported as sustainable yield. A simulation is considered
sustainable if, at steady state (long-term pumping), none of the active basin wells produce water
with chloride concentrations greater than 250 mg/1.
Table 5 reports the maximum sustainable basin yields for baseline scenarios and Table 6 reports
the maximum sustainable basin yields for management scenarios. The purveyor production for
western and central, upper and lower aquifers are also listed. Other production listed in Tables 5
and 6 includes private domestic well production, golf course and community park irrigation well
production and agricultural irrigation well production.
Model results indicate SLR has the lowest potential impact on basin yield, while
reductions in precipitation have the greatest potential impact. Under baseline conditions, the
sustainable yield of the groundwater basin is estimated to be 2,455 acre-feet per year (AFY).
Climate change reduces the baseline yield by 75 AFY due to late-century SLR, by an
additional 125 AFY with increased temperatures, and up to an additional 450 AFY due to
potential declines in precipitation.
Appendix B - SEAWAT RESULTS 7 December 10, 2012
-------
Appendix B
CHG
With the wastewater project and adaptive measures in place (management scenarios), basin yield
with no climate change increases to 3,400 AFY. Climate change reduces this projected basin
yield by 100 AFY due to late-century SLR, by an additional 125 AFY with increased
temperatures, and up to an additional 850 AFY due to potential declines in precipitation (total
decline up to 1,075 AFY; 2,325 AFY basin yield). When comparing management scenarios to
the corresponding baseline scenarios, the wastewater project and adaptive measures increase the
basin yield by 520 AFY to 945 AFY, depending on the scenario.
Table 5
Model Results for Baseline Scenarios
Location
Western Upper
Western Lower
Central Upper
Central Lower
Purveyor Subtotal
Other Production
Basin Yield
Maximum Sustainable Yield for Baseline Scenarios (AFY)
NCb
0
175
400
825
1,400
1,055
2,455
SL55b
0
100
400
825
1,325
1,055
2,380
WSL55b
0
75
400
725
1,200
1,055
2,255
MA2b
0
0
320
430
750
1,055
1,805
LA2b
0
0
375
600
975
1,055
2,030
MBlb
0
150
400
775
1,325
1,055
2,380
LBlb
0
0
360
540
900
1055
1,955
Appendix B - SEAWAT RESULTS
December 10, 2012
-------
Appendix B
CHG
Table 6
Model Results for Management Scenarios
Location
Western Upper
Western Lower
Central Upper
Central Lower
Purveyor Subtotal
Other Production
Basin Yield
Maximum Sustainable Yield for Baseline Scenarios (AFY)
NCm
450
75
890
935
2,350
1,050
3,400
SL55m
450
50
880
870
2,250
1,050
3,300
WSL55m
425
50
860
790
2,125
1,050
3,175
MA2m
200
0
485
590
1,275
1,050
2,325
LA2m
375
0
735
640
1,750
1,050
2,800
MBlm
450
75
870
880
2,275
1,050
3,325
LBlm
250
0
750
600
1,600
1,050
2,650
The management scenarios have greater sustainable basin yields than their respective baseline
scenarios, in large part due to development of the upper aquifer. A greater portion of subsurface
outflow to the bay and ocean is captured through upper aquifer development. In addition, lower
aquifer production is shifted to the east, which increases recharge from Los Osos Creek. Model
results are summarized in the attached Figures 1 and 2.
Seawater Intrusion Front
The leading edge of the seawater intrusion front in the lower aquifer, as defined by the 250 mg/1
isochlor, moves farthest inland along the synclinal axis of the basin. At a steady-state, maximum
sustainable yield condition, the lower aquifer intrusion front has typically advanced beneath the
central area of the basin, while the upper aquifer intrusion front remains beneath the dunes and
bay area. If the maximum yield of a baseline scenario is simulated with the wastewater project
and adaptive measures in place, the seawater intrusion front withdraws from the central basin
area and retreats to the eastern boundary of the dunes and bay area.
Figures 3 through 5 show isoconcentration lines of total dissolved solids (selected to
approximate the 250 mg/1, 500 mg/1, and 2,500 mg/1 isochlor lines) in the upper aquifer for
model scenario LA2b, LA2m, and modified LA2m, respectively. Figures 6 through 11 show the
same isoconcentration lines of total dissolved solids in the two lower aquifer zones for model
scenario LA2b, LA2m, and the modified LA2m scenario.
Appendix B - SEAWAT RESULTS
December 10, 2012
-------
Appendix B
References
California Department of Water Resources, Climate Irrigation Management Information System,
on-line database at http ://wwwcimi s .water . ca. gov/cimi s/info.j sp .
Cleath & Associates, 2005, Seawater Intrusion Assessment and Lower Aquifer Source
Investigation of the Los Osos Valley Groundwater Basin, San Luis Obispo County, California,
prepared for the Los Osos Community Services District, October 2005.
death-Harris Geologists, 2009, Flow Model Conversion and Urban Are Yield Update, Technical
Memorandum to the Los Osos ISJ Group, July 29, 2009.
Guo, W., and Langevin, C.D., 2002, User's Guide to SEAWAT: A Computer Program for
Simulation of Three-Dimensional Variable-Density Ground-Water Flow: U.S. Geological
Survey Techniques of Water Resources Investigations, Book 6, Chapter A7.
Intergovernmental Panel on Climate Change, 2007, AR4 Synthesis Report, Contributions of
Working Group I, II, and III to the Fourth Assessment report of the Intergovernmental Panel on
Climate Change.
Yates and Williams, 2003, Simulated Effects of a Proposed Sewer project on Nitrate
Concentrations in the Los Osos Valley Groundwater Basin, Prepared for the Los Osos
Community Services District and Cleath & Associates, November 6, 2003.
Appendix B - SEAWAT RESULTS 10 December 10, 2012
-------
Appendix B
CHG
I
I
3
2 15OO
500
Mo climate change SL55
WSL5 5 MA2
Climatv Change Scenario
LA2
MB1
LB1
I Baseline Scenarios Management Scenarios
figure 1
Basin Model Results
Climate Ready Utilities Project
Morro Bay NEP
death-Harris Geologists
Appendix B - SEAWAT RESULTS
December 10, 2012
-------
Appendix B
CHG
400
-1200
MA2b
MA2m
LA2b
LA2m MBlb
Climate Change Scenario
MBlm
LBlb
LBlm
ISealevel rise BWarming Precipitation
Appendix B - SEAWAT RESULTS
Figure 2
Basin Yield Impacts Comparison
Climate Ready Utilities Project
Morro Bay NEP
December 10, 2012
death-Harris Geologists
-------
Appendix B
f
7
CHG
Scale 1 inch = 4000 feet
Total Dissolved So lids (IDS) isoconcentrattons in IbTO
0.03 Ib/ft3 = 500 mg/l IDS as 250 mg/l Chloride
0.06 Ib/ft3 = 1,000 mg/l TDS=> 500 me/I Chloride
0.31 Ih/ft3 = 5,000 mg/l TDSs 2,500 mg/l Chloride
Baseline Scenario
Late Century A2 Emissions
Well Production 2,030 AFY
Figure 3
Upper Aquifer (Zone C)
TDS [soconcentrations
Scenario LA2b
Climate Ready Utilities Project
Morro Bay NEP
death-Harris Geologists
Appendix B - SEAWAT RESULTS
December 10, 2012
-------
Appendix B
CHG
y1 DUldESANDBAY ,. " ,,, '
Scale 1 inch = 4000 feet
Total Dissolved Solids (IDS) isoconcentrations in IbftS
0.03 Ib/ft3 = 500 mgfl IDS a 250 mg/l Chloride
0.06 IrVftS = 1,000 mg/l TDSs 500 mg'l Chloride
0.31 IWft3 = 5,000 mg/l TDSs 2,500 mg/l Chloride
Management Scenario
Late Century A2 Emissions
Well Production 2,800 AFY
Figure -1
Upper Aquifer (Zone C)
TDS Isoconcentrations
Scenario LA2rn
Climate Ready Utilities Project
Morra Bay NEP
death-Harris Geologists
Appendix B - SEAWAT RESULTS
December 10, 2012
-------
Appendix B
CHG
Scale 1 inch = 4000 feet
Total Dissolved Solids (IDS) isoconcentratbns in Ibft3
0.03 IWftS = 500 mg!\ IDS = 250 mg/l Chloride
0.06 Ib/ft3 = 1,000 mg/l TDS= 500 mg/l Chkjride
0.31 IWftS = 5,000 mg/l TDSs 2,500 mg/l Chloride
Management Soenario (modified)
Late Century A2 Emissions
Well Production 2,030 AFY
Figure 5
Upper Aquifer (Zone C)
TDS Isoconcentrations
MODIFIED Scenario LA2m
Climate Ready Utilities Project
Morro Bay NEP
death-Harris Geologists
Appendix B - SEAWAT RESULTS
December 10, 2012
-------
Appendix B
CHG
Scale 1 inch = 4000 feet
Total Dissolved Solids (IDS) isoconcentrations in IbftS
0.03 Ib/ft3 = 500 mg'l IDS ~ 250 mg/l Chloride
0.06 IhffB = 1,000 mg/l TDS~ 500 mg/l Chloride
0.31 Ib/ft3 = 5,000 mg/l TDS~ 2,500 mg^l Chloride
Baseline Scenario
Late Century A2 Emissions
Well Production 2,030 AFY
Figure 6
Lower Aquifer (Zone D)
TDS Isoconcentrations
Scenario LA2b
Climate Ready Utilities Project
Morro Bay NEP
death-Harris Geologists
Appendix B - SEAWAT RESULTS
December 10, 2012
-------
Appendix B
CHG
J WESTERN
N
A
1 inch = 4000 feet
Total Dissolved Solids (TDS) isoconcentratbns in IbftS
0.03 Ib/ft3 = 500 mg/l TDS => 250 mg/l Chloride
0.06 Ib/ft3 = 11,000 mg/l TDS~ 500 mg'l Chbrtde
0.31 Ib/ft3 =5,000 mg/l TDS~ 2,500 mg/l Chloride
Management Scenario
Late Century A2 Emissions
Well Production 2,800 AFY
Figure 7
Lower Aquifer (Zone D)
TDS Isoconcentrations
Scenario LA2m
Climate Ready Utilities Project
Morro Bay NEP
death-Harris Geologists
Appendix B - SEAWAT RESULTS
December 10, 2012
-------
Appendix B
CHG
Scale 1 inch = 4000 feet
Total Dissolved Solids (IDS) isoconcentratbns in IbttS
0.03 IWftS = 500 mg/l TDS ~ 250 mg/l Chloride
0.06 Ih/ft3 = 1,000 mg/l TDS~ 500 mg'l Chloride
0.31 IWfB = 5,000 mg/l TDS« 2,500 mg'l Chloride
Management Scenario (modified)
Late Century A2 Emissions
Well Production 2,030 AFY
Figure 8
Lower Aquifer (Zone D)
TDS Isoconcentrations
MODIFIED Scenario LA2m
Climate Ready Utilities Project
Morro Bay NEP
Cleath-Harris Geologists
Appendix B - SEAWAT RESULTS
December 10, 2012
-------
Appendix B
CHG
Scale 1 inch = 4000 feet
Total Dissolved Solids [TDSjisoconcentrations in IbftS
0.03 IWftS = 500 mg'l IDS ~ 250 mg/l Chloride
0.06 IWftS = 1,000 mg/l TDS~ 500 mg/l Chloride
0.31 Ib/ft3 = 5,000 mg/l IDS- 2,500 mg/l Chloride
Baseline Scenario
Late Century A2 Emissions
Well Production 2,030 AFY
Figure 9
Lower Aquifer (Zone E)
IDS Isoconcentrations
Scenario LA2b
Climate Ready Utilities Project
Morro Bay NEP
death-Harris Geologists
Appendix B - SEAWAT RESULTS
December 10, 2012
-------
Appendix B
CHG
DUrijESANDBAY / /
S
Scale 1 inch = 40DD feet
Total Dissolved Solids (IDS) isoconcentrations in Ibft3
0.03 Ih/ft3 = 500 mg/l TDS = 250 mg/l Chloride
O.OB Ib'ftS = 1,000 mg/l TDS= 500 mg^l Chbride
0.31 Ib'ftS = 5,000 mg/l TDS~ 2,500 mg'l Chloride
Management Scenario
Late Century A2 Emissions
Wei I Production 2,BOO AFY
Figure 10
Lower Aquifer (Zone E)
TDS Isoconcentrations
Scenario LA2m
Climate Ready Utilities Project
Morro Bay NEP
death-Harris Geologists
Appendix B - SEAWAT RESULTS
December 10, 2012
-------
Appendix B
/^=^
/ $t '^?
// ^r
DUrilESANDBAYv
CHG
Scale 1 inch = 4000 feet
Total Dissolved So lids (TDS) isoooncentrations in IbTO
0.03 Ih/ft3 = 500 mg/l TDS ~ 250 mg/l Chloride
0.06 IWft3 = 1,000 mg/l TDS~ 500 mgfl Chloride
0.31 Ib/ft3 =5,000 mg/l TDS~ 2,500 mg/l Chloride
Management Scenario (modified)
Late Century A2 Emissions
Well Production 2,030 AFY
Figure 11
Lower Aquifer (Zone E)
TDS Isoconcentrations
MODIFIED Scenario LA2m
Climate Ready Utilities Project
Morro Bay NEP
death-Harris Geologists
Appendix B - SEAWAT RESULTS
December 10, 2012
-------
Appendix C
MONTHLY COMPARISON OF MODEL RUN RESULTS PROVIDED BY
GREAT AND CAL-ADAPT
FEBRUARYS, 2012
The attached plots present a second comparison of the model run results provided in the
GREAT and Cal-Adapt. In this case, the projected conditions from one model (CNRM) in
Cal-Adapt are compared to the GREAT ranges for each calendar month during two time
periods (mid- and late-century). General descriptions of the data provided within each tool
are provided below:
All data drawn from tools for suggested location based on match to baseline (historical)
climate conditions (35.4500 °N 120.8125 °W).
GREAT provides statisitcs based on 112 runs using 16 different models and 3 emission
scenarios (IPCC SRES A2, A1B, and B1). Specifically, GREAT presents a range of model
results for two 30-year time periods (mid- and late-century) defined by the lowest (MIN) and
the highest (MAX) average model run result.
Cal-Adapt provides direct download of the monthly outputs from a sub-set of the model run
population used for GREAT and include two emission scenarios (IPCC SRES A2 and B1)
chosen to provide a range of possible climate change based on a range of emission
projections.
Based on previous comparison of annual projections, the models included in Cal-Adapt
projected drier conditions than indicated by the range of model projections in GREAT.
One specific model (CNRM) was chosen as representative of a more significant challenge
to the system.
For the purpose of comparison, the model run results from both tools were averaged over
the same 30-year periods (2040 to 2069 for mid-century and 2070 to 2099 for late-century).
The following plots and data tables are provided as a proposal for SEA WAT inputs to use for
each GREAT time period. Additional details:
These conditions would be based on CNRM outputs and would tend to define drier
conditions.
CNRM and GREAT baselines describe slightly different seasonal patterns due to different
sources (model versus observations); however, the projected changes from CNRM are
used and only one baseline (from GREAT) is used in comparison of projected conditions.
Scenarios with negligible changes in precipitation (while temperature still increases) could
also be considered in SEAWAT, then GREAT, if they would lead to useful and different
conditions.
-------
Appendix C
Mid-Century CNRM results v. CREAT Range (30-year averages)
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TEMP MID
(°C)
CNRM
Baseline A2
CNRM
Baseline B1
CREAT
Baseline
CNRM A2
CNRM B1
Jan
10.72
10.73
8.27
8.59
8.99
Feb
11.64
11.62
9.90
10.23
10.55
Mar
12.02
11.99
11.33
11.68
12.00
Apr
13.43
13.39
13.43
13.77
13.81
May
14.50
14.52
16.81
17.35
17.38
Jun
16.28
16.39
19.99
20.65
20.57
Jul
17.70
17.76
22.65
23.46
23.48
Aug
18.03
17.92
22.38
23.37
23.53
Sep
17.83
17.79
20.51
21.59
21.62
Oct
16.53
16.51
16.63
17.54
17.56
Nov
13.77
13.75
11.35
12.09
12.11
Dec
11.29
11.25
8.11
8.51
8.91
Projected Monthly Precipitation (mm)
Mid-Century CNRM results v. GREAT Range (30-year averages)
x ,
1^ /a CNRMB1
V 1
\ \ j CREAT
\ '
,
* * \
/ *
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-------
Appendix C
Late-CenturyCNRM results v. GREAT Range (30-year averages)
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Late-CenturyCNRM results v. CREAT Range (30-year averages)
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fP ^ ^ ^ ^ V*N V& f$ Q^ &>* Oe°
PRECIP
LATE (mm)
CNRM
Baseline A2
CNRM
Baseline B1
CREAT
Baseline
CNRM A2
CNRM B1
Jan
128.69
128.71
96.75
90.29
82.59
Feb
85.44
92.11
89.09
82.74
79.62
Mar
76.25
76.22
72.88
23.59
23.51
Apr
34.99
34.98
33.60
10.59
17.16
May
10.83
10.84
9.17
1.75
3.19
Jun
1.45
1.45
1.05
0.68
0.68
Jul
1.26
1.25
0.45
1.63
0.98
Aug
0.22
0.22
1.15
7.19
4.75
Sep
3.08
3.09
6.98
40.49
17.98
Oct
13.34
13.35
16.74
16.31
20.63
Nov
56.35
56.37
45.76
39.74
42.91
Dec
86.51
86.57
72.07
68.22
68.99
-------
Appendix D
Baseline and Resilience Consequence Weighting
Proposed Changes by the Morro Bay Workgroup
Baseline Analysis
Asset -Threat Pairs
Reduced Recharge-Los Osos Creek 2050
Reduced Recharge-Los Osos Creek 2100
Reduced Recharge -Warden Creek 2050
Reduced Recharge-Warden Creek 2100
Reduced Recharge -Willow Creek 2050
Reduced Recharge -Willow Creek 2100
Reduced Recharge -Morro Bay Estuary 2050
Reduced Recharge -Morro Bay Estuary 2100
Reduced Recharge-Los Osos Upper Aquifer 2050
Reduced Recharge-Los Osos Upper Aquifer 2100
Reduced Recharge-Los Osos Lower Aquifer 2050
Reduced Recharge-Los Osos Lower Aquifer 2100
Saline Intrusion -Morro Bay Estuary 2050
Saline Intrusion -Morro Bay Estuary 2100
Saline Intrusion-Los Osos Upper Aquifer 2050
Saline Intrusion -Los Osos Upper Aquifer 2100
Saline Intrusion -Los Osos Lower Aquifer 2050
Saline Intrusion -Los Osos Lower Aquifer 2100
Utility-
Business
Impact
Very High
Very High
Low
Low
Very High
Very High
Low
Low
Very High
Very High
Very High
Very High
Low
Low
Very High
Very High
Very High
Very High
Equipment/Facility
Impact
Medium
Medium
Low
Low
Medium
Medium
Low
Low
Medium
Medium
Medium
Medium
Low
Low
Medium
Medium
Medium
Medium
Sou r ce/Receivin g
Water Impact
Very High
Very High
Low
Low
Very High
Very High
Low
Low
Very High
Very High
Very High
Very High
Very High
Very High
Very High
Very High
Very High
Very High
Environmental
Impact
Very High
Very High
Very High
Very High
Very High
Very High
Very High
Very High
Medium
Medium
Medium
Medium
Very High
Very High
Medium
Medium
Medium
Medium
Community
Impact
Medium
Medium
Low
Low
Medium
Medium
Low
Low
Medium
Medium
Medium
Medium
Low
Low
Medium
Medium
Medium
Medium
-------
Appendix D
Resilience Analysis
Asset -Threat Pairs
Reduced Recharge-Los Osos Creek 2050
Reduced Recharge-Los Osos Creek 2100
Reduced Recharge -Warden Creek 2050
Reduced Recharge -Warden Creek 2100
Reduced Recharge -Willow Creek 2050
Reduced Recharge -Willow Creek 2100
Reduced Recharge -Morro Bay Estuary 2050
Reduced Recharge -Morro Bay Estuary 2100
Reduced Recharge-Los Osos Upper Aquifer 2050
Reduced Recharge-Los Osos Upper Aquifer 2100
Reduced Recharge-Los Osos Lower Aquifer 2050
Reduced Recharge-Los Osos Lower Aquifer 2100
Saline Intrusion -Morro Bay Estuary 2050
Saline Intrusion -Morro Bay Estuary 2100
Saline Intrusion-Los Osos Upper Aquifer 2050
Saline Intrusion -Los Osos Upper Aquifer 2100
Saline Intrusion -Los Osos Lower Aquifer 2050
Saline Intrusion -Los Osos Lower Aquifer 2100
Utility-
Business
Impact
Medium
Medium
Low
Low
Medium
Medium
Low
Low
Medium
Medium
Medium
Medium
Low
Low
Medium
Medium
Medium
Medium
Equipment/Facility
Impact
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Source/Receiving
Water Impact
Medium
Medium
Low
Low
Medium
Medium
Medium
Medium
Medium
Medium
Medium
Medium
Very High
Very High
Medium
Medium
Medium
Medium
Environmental
Impact
Very High
Very High
Very High
Very High
Very High
Very High
Very High
Very High
Medium
Medium
Medium
Medium
Very High
Very High
Medium
Medium
Medium
Medium
Community
Impact
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
-------
Appendix D
Table 1. Additional Comments to Consequence Weighting - Baseline Analysis
Asset-Threat Pair Comment from Workgroup
Reduced Recharge-Warden Creek 2050
Reduced Recharge-Warden Creek 2100
Changed Consequence Level to "Low" for all
categories except Environmental Impact, which
will remain "Very High". Warden Creek does not
provide significant recharge to the groundwater
basin. Los Osos and Willow Creeks recharge the
basin.
Reduced Recharge-Morro Bay Estuary 2050
Reduced Recharge-Morro Bay Estuary 2100
The Consequence Level was set to "Low" based on
the asset's contribution to recharging the
Groundwater Basin for all categories except
Environmental Impact, which will remain "Very
High".
Reduced Recharge-Los Osos Upper Aquifer 2050
Reduced Recharge-Los Osos Upper Aquifer 2100
Reduced Recharge-Los Osos Lower Aquifer 2050
Reduced Recharge-Los Osos Lower Aquifer 2100
Saline Intrusion-Los Osos Upper Aquifer 2050
Saline Intrusion-Los Osos Upper Aquifer 2100
Saline Intrusion-Los Osos Lower Aquifer 2050
Saline Intrusion-Los Osos Lower Aquifer 2100
List Environmental Impact as "Medium" on the
Upper and Lower Aquifers in the Baseline and
Resilience Analysis for both threats to avoid double
counting impacts to source/receiving waters.
Saline Intrusion-Morro Bay Estuary 2050
Saline Intrusion-Morro Bay Estuary 2100
The Consequence Level was set to "Low" based on
the asset's contribution to recharging the
Groundwater Basin for all categories except
Environmental Impact and Source/Receiving Water
Impact, which will remain "Very High".
-------
Appendix D
Table 2. Additional Comments to the Consequence Weighting - Resilience Analysis
Asset-Threat Pair Comment from Workgroup
Reduced Recharge-Los Osos Creek 2050
Reduced Recharge-Los Osos Creek 2100
The adaptive measures mitigate the threat of
reduced recharge to groundwater from Los Osos
Creek by increasing stream seepage. The change
from "High" to "Medium" Consequence Levels
makes sense for the Source/Receiving Water
Impacts. What's not clear is how the environmental
impacts to Los Osos Creek would also be mitigated
through the adaptive measures, as these impacts are
generally associated with ecosystems, not
groundwater systems, and are likely the same or
greater as surface flows are decreased. Proposed
that Environmental Impacts stay "Very High".
Reduced Recharge-Warden Creek 2050
Reduced Recharge-Warden Creek 2100
Warden Creek does not significantly recharge the
groundwater basin. As such there would be no
change to Consequence Levels resulting from
adaptive measures. Source/Receiving Water
Impacts will be "Low", while Environmental
Impacts will be "Very High".
Reduced Recharge-Willow Creek 2050
Reduced Recharge-Willow Creek 2100
Willow Creek dynamics would be similar to Los
Osos Creek (mitigation of reduced basin recharge
and less average surface flows with adaptive
measures). Source/Receiving Water Impacts will
be "Medium"; Environmental Impacts remains
"Very High".
Reduced Recharge-Morro Bay Estuary 2050
Reduced Recharge-Morro Bay Estuary 2100
The Estuary does not recharge the groundwater
basin (significantly), and there would be no
permanent changes to consequence levels resulting
from implementation of the selected adaptive
measures. Although it is possible that under
adaptive measures and drought, there could be
temporary impacts on water quality locally (upper
aquifer supply well). Source/Receiving Water
Impacts are "Medium", and Environmental Impacts
remain "Very High".
Reduced Recharge-Morro Bay Estuary 2050
Reduced Recharge-Morro Bay Estuary 2100
Saline Intrusion-Morro Bay Estuary 2050
Saline Intrusion-Morro Bay Estuary 2100
A greater portion of subsurface outflow to the Bay
is captured through upper aquifer development
adaptive measures. The potential impacts of sea
level rise on the Bay fringe ecosystem could also
exceed any change in groundwater outflow.
Adaptive measures will not mitigate the potential
threat of saline intrusion to Morro Bay. Therefore,
the Source/Receiving Water and Environmental
Impacts both remain "Very High".
-------
Appendix D
Table 3. Consequence Evaluation Criteria
Attributes
Utility
Business
Impact
Equipment/
Facility
Impact
Source /
Receiving
Water
Impact
Environment
al Impact
Community
Public Health
Impact
Very High
Long-term and/or
significant loss of
expected utility
revenue or operating
income
Complete loss of
asset; replacement
costs of SX++1
Long-term
compromise of water
quality and/or
quantity
environmental
damage - may incur
regulatory action
Long-term and/or
widespread public
health impacts
High
episodic - but
minor -compromise
of expected utility
revenue or
operating income
Significant damage
to equipment; costs
estimated at <$X+
Seasonal or
episodic
compromise of
water quality
and/or quantity
Persistent
environmental
damage - may
incur regulatory
action
Short-term and
localized public
health impacts
Medium
Minor and short-
term reductions in
expected utility
revenue or operating
income
Minor damage to
equipment; costs
estimated at <$X
Temporary impact
on water quality
and/or quantity
Short-term
environmental
damage -
compliance can be
quickly restored
Minor public health
impacts
Low
Minimal potential
for any
attributable loss of
utility revenue or
operating income
Minimal damage
to equipment
No more than
minimal changes
to water quality
and/or quantity
No impact or
environmental
damage
No impact on
public health
1 This notation, "$X," reflects a flexible cost scale which can be customized by each user when additional
information is available.
------- |