San Clemente City Council
November 18, 2025

SAN CLEMENTE NATURE-BASED

ADAPTATION PROJECT

FEASIBILITY STUDY
By Moffatt & Nichol, in Coordination with Coastal
Frontiers Corporation, GHD, Coastal Restoration
Consultants, and CETO

FINAL REPORT
Produced for the City of San Clemente
November 11, 2025
Attachment 1
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente i
Table of Contents
EXECUTIVE SUMMARY...............................................................................................................................X

1. INTRODUCTION.............................................................................................................................. 1

1.1. Background and Statement of the Problem ................................................................................................. 2

1.2. City Goals and the Purpose of This Study.................................................................................................. 10

1.3. Related City & Regional Coastal Resiliency Building Efforts ................................................................... 12

2. EXISTING CONDITIONS ............................................................................................................... 16

2.1. General Shoreline Conditions Within the City and South Orange County .............................................. 16

2.1.1. The Littoral Cell ............................................................................................................................... 16

2.1.2. The Sediment Budget...................................................................................................................... 18

2.1.3. The Shoreline Position .................................................................................................................... 21

2.2. Sediment Grain Size...................................................................................................................................... 29

2.3. Responses to Erosion .................................................................................................................................. 31

2.4. Study Reaches Within the City .................................................................................................................... 34

2.5. Critical Erosion Hotspots ............................................................................................................................. 36

2.6. Opportunities................................................................................................................................................. 39

2.7. Constraints .................................................................................................................................................... 43

2.8. Summary of Overall Advantages and Disadvantages for Each Proposed Pilot Project ........................ 50

3. CONCEPTUAL ALTERNATIVES DEVELOPMENT PROCESS.................................................... 57

3.1. Additional Background for NBS Alternatives............................................................................................. 57

3.2. The Process of Identifying NBS Alternatives ............................................................................................. 57

3.2.1. Screening Alternatives..................................................................................................................... 58

3.2.2. Range of Possible Options (Book Ends) ......................................................................................... 60

3.3. Vetting the Initial City Concepts with the Public........................................................................................ 63

3.4. Revised Draft Sand Retention Concepts – Phase 1 (Near Term).............................................................. 64

3.4.1. Concept 1 – North Beach Multi-Benefit Emergent Breakwater ....................................................... 64

3.4.2. Concept 2 – Capistrano Shores Multi Benefit Submerged Breakwater and “Speed Bumps”.......... 76

3.4.3. Concept 3 – State Beach Multi-Benefit Emergent Breakwater........................................................ 87

4. FEASIBILITY ANALYSES OF THE DESIGN CONCEPTS............................................................ 99

4.1. North Beach Multi-Benefit Emergent Breakwater ...................................................................................... 99

4.1.1. Predictive Performance at Building and Retaining the Beach ......................................................... 99

4.1.2. Costs ............................................................................................................................................. 102

4.1.3. Economic Benefits......................................................................................................................... 104

4.1.4. Regulatory Processes ................................................................................................................... 106

4.1.5. Sea Level Rise Resilience/Adaptability ......................................................................................... 108

4.2. Capistrano Shores Submerged Breakwater and “Speed Bumps” ......................................................... 110

4.2.1. Predictive Performance at Building Beaches ................................................................................ 110

4.2.2. Costs ............................................................................................................................................. 113

4.2.3. Economic Benefits......................................................................................................................... 115

4.2.4. Regulatory Processes ................................................................................................................... 117 Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente ii

4.2.5. Sea Level Rise Resilience/Adaptability ......................................................................................... 117

4.3. State Beach Multi-Benefit Emergent Breakwater..................................................................................... 120

4.3.1. Predictive Performance at Building Beaches ................................................................................ 120

4.3.2. Costs ............................................................................................................................................. 122

4.3.3. Economic Benefits......................................................................................................................... 122

4.3.4. Regulatory Processes ................................................................................................................... 124

4.3.5. Sea Level Rise Resilience/Adaptability ......................................................................................... 124

4.4. General Assessment of Overall Project Concept Feasibility .................................................................. 127

5. RECOMMENDATIONS AND NEXT STEPS ................................................................................ 129

5.1. Regional Funding Options ......................................................................................................................... 130

5.1.1. Federal .......................................................................................................................................... 130

5.1.2. State .............................................................................................................................................. 131

5.1.3. Local.............................................................................................................................................. 133

5.1.4. Special Tax Districts ...................................................................................................................... 134

6. CONCLUSIONS........................................................................................................................... 135

7. REFERENCES............................................................................................................................. 137 List of Appendices
APPENDIX A. PUBLIC MEETING #1 PRESENTATION – 09/27/2023 APPENDIX B. PUBLIC MEETING #2 PRESENTATION – 02/29/2024 APPENDIX C. PUBLIC MEETING #3 PRESENTATION – 07/18/2024 APPENDIX D. ALTERNATIVES SCREENING GRAPHICS
APPENDIX E. SAN CLEMENTE SAND RETENTION PERFORMANCE SUMMARY APPENDIX F. ECONOMIC METHODOLOGY AND RESULTS
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List of Figures
Figure 1-1: Regional Location of the City of San Clemente and Local Landmarks .......................................................................... 4 Figure 1-2: Historic Shoreline Map of the City of San Clemente ...................................................................................................... 5 Figure 1-3: Historical Aerial (1960) of the North End of the City of San Clemente ........................................................................... 6 Figure 1-4: Historical Aerial (1960) of the South End of the City of San Clemente .......................................................................... 7 Figure 1-5: North Beach Near the North End of the City in the 1993 (Bottom) in the Early 2019 (Top) ........................................... 8 Figure 1-6: Cyprus Shore at the South End of the City in 2014 (Bottom) in 2020 (Top)................................................................... 9 Figure 1-7: Phase 0 – Current and Planned San Clemente Beach Nourishment Projects............................................................. 13 Figure 2-1: Oceanside Littoral Cell, Northern Sub-Cell (Patsch and Griggs 2023)......................................................................... 17 Figure 2-2: Doheny Beach Shoreline Pre- and Post-Construction of Dana Point Harbor............................................................... 19 Figure 2-3: CoastSat Shoreline Transect Trends Along the Capistrano Bight Since 2000 (Vos, et al. 2019) ................................ 23 Figure 2-4: San Clemente Beach Monitoring Program – Beach Profile Transect Location Map .................................................... 24 Figure 2-5: Spring 2025 MHW Beach Widths Relative to 1984-2024 Historical Fall Beach Width Envelope................................. 28 Figure 2-6: Composite Sediment Grain Size Envelope for San Clemente Pier Area ..................................................................... 30 Figure 2-7: Damaged Access Road to San Onofre State Beach from January 2023 Storms. Source: Surfrider Foundation ........ 33 Figure 2-8: San Clemente Shoreline Reaches & City Beach Profile Locations (Surveyed by Coastal Frontiers Corporation, 2023) ....................................................................................................................................................... 35 Figure 2-9: San Clemente City-Owned Shoreline Reach ............................................................................................................... 41 Figure 2-10: Biological Resources in San Clemente. Source: (Everest International Consultants 2013)....................................... 45 Figure 2-11: Wheeler Reef Locations as of 2024. .......................................................................................................................... 47 Figure 2-12: Surfing Sites Within the City ....................................................................................................................................... 48 Figure 3-1: Conceptual Schematic for North Beach Multi-Benefit Emergent Breakwater............................................................... 66 Figure 3-2: Conceptual Schematic for Concept 2 – Capistrano Shores Multi-Benefit Submerged Breakwater and “Speed Bumps”......................................................................................................................................................................... 76 Figure 3-3: Conceptual Schematic 3 – State Beach Multi-Benefit Emergent Breakwater .............................................................. 88 Figure 4-1: Predicted Sand Retention Performance of the North Beach Multi-Benefit Emergent Breakwater ............................. 101 Figure 4-2: Expected NMV Loss Due to Coastal Erosion With and Without Replenishment at North Beach............................... 105 Figure 4-3: Anticipated Salient Dimensions for the Submerged Breakwater Concept at Capistrano Shores............................... 112 Figure 4-4: Expected NMV Loss Due to Coastal Erosion With and Without Replenishment at Capistrano Shores ..................... 116 Figure 4-5: Anticipated Salient Dimensions for the Multi-Benefit Emergent Breakwater at San Clemente State Beach.............. 121 Figure 4-6: Expected NMV Loss Due to Coastal Erosion With and Without Replenishment at State Beach ............................... 123 Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente iv
List of Tables
Table 2-1: Beach Profile Characteristics in South Orange County Sub-Reaches .......................................................................... 25 Table 2-2: Beach Width Changes in South Orange County Sub-Reaches, 2001 to 2024/2025..................................................... 27 Table 2-3: Critical Erosion Hotspots Memo Reach Parameters Criteria and Designations Matrix ................................................. 36 Table 2-4: Reach Criticality Matrix Based on Fall 2024 CFC San Clemente Shoreline Monitoring Results ................................... 38 Table 2-5: Summary of Advantages and Disadvantages for Each Potential Project Site............................................................... 56 Table 3-1: Matrix of Possible Design Alternatives Used for the Screening Process....................................................................... 61 Table 3-2: Summary of North Beach Concept Characteristics ....................................................................................................... 68 Table 3-3: Summary of Capistrano Shores Concept Characteristics ............................................................................................. 79 Table 3-4: Summary of State Beach Concept Characteristics........................................................................................................ 90 Table 4-1: Conceptual Level Implementation Costs for the North Beach Multi-Benefit Emergent Breakwater ............................ 103 Table 4-2: North Beach Multi-Benefit Emergent Breakwater Permitting Actions .......................................................................... 107 Table 4-3: Sea Level Rise Projections Evaluated for the City SLRVA and the NBFS.................................................................. 108 Table 4-4: North Beach Multi-Benefit Emergent Breakwater SLR................................................................................................ 108 Table 4-5: Conceptual Level Implementation Costs for the Capistrano Shores Submerged Breakwater .................................... 114 Table 4-6: Sea Level Rise Projections Evaluated for the City SLRVA and the NBFS.................................................................. 118 Table 4-7: Capistrano Shores Multi-Benefit Submerged Breakwater and “Speed Bumps” SLR .................................................. 118 Table 4-8: Sea Level Rise Projections Evaluated for the City SLRVA and the NBFS.................................................................. 125 Table 4-9: State Beach Multi-Benefit Emergent Breakwater SLR ................................................................................................ 125 Table 4-10: Design Concepts Scorecard...................................................................................................................................... 128 Table 5-1: Federal Funding Opportunities .................................................................................................................................... 132 Table 5-2: State Funding Opportunities ........................................................................................................................................ 133 Table 5-3: Local Funding Opportunities........................................................................................................................................ 133 Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente v
Disclaimer
Moffatt & Nichol devoted effort consistent with (i) the level of diligence ordinarily exercised by competent professionals practicing in the area under the same or similar circumstances, and (ii) the time and budget available for its work, to ensure that the data contained in this report is accurate as of the date of its preparation. This study is based on estimates, assumptions and other information developed by Moffatt & Nichol from its independent research effort, general knowledge of the industry, and information provided by and consultations with the client and the client's representatives. No responsibility is assumed for inaccuracies in reporting by the Client, the Client's agents and representatives, or any third-party data source used in preparing or presenting this study. Moffatt & Nichol assumes no duty to update the information contained herein unless it is separately retained to do so pursuant to a written agreement signed by Moffatt & Nichol and the Client.

Moffatt & Nichol’s findings represent its professional judgment. Neither Moffatt & Nichol nor its respective affiliates make any warranty, expressed or implied, with respect to any information or methods disclosed in this document. Any recipient of this document other than the Client, by their acceptance or use of this document, releases Moffatt & Nichol and its affiliates from any liability for direct, indirect, consequential or special loss or damage whether arising in contract, warranty (express or implied), tort or otherwise, and irrespective of fault, negligence and strict liability.

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This document was prepared solely for the use by the Client. No party may rely on this report except the Client or a party so authorized by Moffatt & Nichol in writing (including, without limitation, in the form of a reliance letter). Any party who is entitled to rely on this document may do so only on the document in its entirety and not on any excerpt or summary. Entitlement to rely upon this document is conditioned upon the entitled party accepting full responsibility and not holding Moffatt & Nichol liable in any way for any impacts on the forecasts or the earnings from the project resulting from changes in "external" factors such as changes in government policy, in the pricing of commodities and materials, price levels generally, competitive alternatives to the project, the behavior of consumers or competitors and changes in the owners’ policies affecting the operation of their projects.

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This study is qualified in its entirety by, and should be considered in light of, these limitations, conditions and considerations.

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Glossary
BRIC Building Resilient Infrastructure and Communities
Caltrans California Department of Transportation
CCC California Coastal Commission
CCSTWS-SD Coast of California Storm and Tidal Waves Study – San Diego CEQA California Environmental Quality Act
CDBG-MIT Community Development Block Grant Mitigation
City City of San Clemente
CRD Climate Resilience Districts
CSCC California State Coastal Conservancy
DCIP Defense Community Infrastructure Program
DOD Department of Defense
EPA United States Environmental Protection Agency
GHAD Geological Hazard Abatement District
HUD United States Department of Housing and Urban Development IP Implementation Plan
LCP Local Coastal Program
LOSSAN Los Angeles-San Diego-San Luis Obispo
LUP Land Use Plan
MHW Mean High Water
MHHW Mean Higher High Water
MHTL Mean High Tide Line
MPO Metropolitan Planning Organization
NAVD88 North American Vertical Datum 1988
NBFS Nature-Based Adaption Feasibility Study
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NBS Nature Based Solutions
NEPA National Environmental Policy Act
NFWF National Fish and Wildlife Fund
NOAA National Ocean and Atmospheric Administration
OCTA Orange County Transportation Authority
RBSP Regional Beach Sand Project
REP Readiness and Environmental Protection
ROW Right-of-Way
RR Railroad
RWQCB Regional Water Quality Control Board
SANDAG San Diego Association of Governments
SCOUP San Clemente Sand Compatibility and Opportunistic Use Program SCUG Sand Compatibility and Use Guidelines
SLC California State Lands Commission
SLR Sea Level Rise
SLRVA Sea Level Rise Vulnerability Assessment
State Parks California Department of Parks and Recreation USACE United States Army Corps of Engineers
USDOT United States Department of Transportation
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Introduction to the Final
San Clemente Nature Based Adaptation Project Feasibility Report Foreword
The City of San Clemente (City) initiated efforts on the Nature Based Adaptation Project Feasibility Study in the Fall of 2022 after securing a $300,000 grant from the California Coastal Commission (CCC).

The City retained a multi-disciplinary team of coastal experts to assist with the project including engineers, scientists, planners, economists, biologists and ecologists to develop nature-based sand retention design concepts that could be integrated into the City’s comprehensive shoreline management plan focused on building long term coastal resilience in San Clemente.

The City’s efforts aim to protect the City’s beaches, expand coastal resilience, and promote access for all communities including residents and visitors. The City is working with nature to protect what matters most: the world class beaches that connect and serve the community and support natural resources and the coastal ecosystem. This project reflects the City’s commitment to resilience, preservation, and equitable coastal access.

This project is a powerful example of how local governments can work with nature to protect the coast, strengthen climate resilience, and preserve public beach access for generations to come.

By investing in science-based, community-driven solutions, the City seeks to ensure the beach remains a place of connection, recreation, and refuge for all.

By protecting the coastline, the projects will also ensure public access to the beach, especially for families and communities who rely on these spaces for relaxation, recreation and relief from inland heat for decades to come.

This Final Report represents the culmination of a three-year siting and conceptual design process which benefited significantly from community input obtained through an iterative process at discrete intervals over the last three years.

The team is grateful for the high level of engagement from the community and for all of the useful suggestions and feedback received. Community input and City leadership has been fully integrated and is reflected throughout this Final Report.

Summary
The City published the Draft NBAS Report (Draft Report) on June 10, 2025, and received comments during a two-month long public review and comment period that ran through August 14, 2025.

A total of 94 comment letters and emails with comments on the Draft Report were received by the City and are published on the City website at https://san-clemente.org/sand.

Sixty-three of the comment letters and emails were received from residents in the Shorecliffs/Poche community requesting consideration of a structure offshore in the northern most part of the City of San Clemente.

Other main and recurring themes of the comment letters are summarized below:

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• Support for the recommendations in the Draft Report ranking North Beach highest as a first priority for a pilot project in terms of benefits to costs; • Support for an offshore structure at State Beach;
• Support for a structure at Capistrano Shores;
• Design concept refinements such as submerged versus emergent reefs; • Avoidance of adverse effects on important surf breaks; • Economics should not factor into prioritizing an offshore structure, and • Investment in the beach is critical to the San Clemente way of life/culture.

Other comment letters were focused on other aspects of the City’s shoreline management strategy of which sand retention is one component in addition to sand replenishment.

Some of the commentors noted errors (including typos) that have been corrected in the final version of the Report which are shown in redline / strikeout to facilitate reader review.

Comments from staff of the California Coastal Commission (CCC) acknowledged appreciation of the City’s robust multi-year public outreach program soliciting community input which was then used to refine the draft designs and related considerations.

CCC staff also requested additional information and clarifications on several fronts including explaining why “living shorelines/sand dunes” are proposed as a future phase and not planned for implementation now and more description of the ecological benefits of the proposed offshore reef/breakwater structures.

CCC staff also requested clarifications on how the mean high tide line could shift seaward with project implementation, plans for monitoring, adaptive management and effects on sand transport. Lastly, CCC staff requested more information on public access, recreational benefits, sea level rise, sand supply, environmental justice, evaluation criteria used to rank the concepts, and project performance goals.

All changes to the document that have been made since the Draft Report was published in June 2025 are shown in Track Changes to facilitate reader review of the revisions.

The City hopes to move into design development, engineering, testing (computer simulations as well as physical testing of scaled prototypes), environmental review and permitting in 2026-2028, with an aim to start construction in the coming years depending on funding availability.

Community engagement will continue to be a key part of the City’s process—including public meetings, email updates, and presentations to ensure transparency and help shape the design of the project.

Beach sand replenishment, sand retention and future living shorelines/sand dunes are key pieces of the City’s broader coastal resilience planning efforts to protect and enhance beaches through science, partnerships and public participation now and in the future.

For more information on the City’s efforts, to sign up for email updates about project milestones and community engagement opportunities and to join the City in building a more resilient San Clemente coastline please check out https://san-clemente.org/sand Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente x
Executive Summary
Background and Problems
San Clemente is a southern California coastal city with nearly 5 miles of beautiful coastline.

Beaches have been central to the City’s identity since incorporation in 1928. However, beaches along the City’s coast are narrowing due to lack of sand supply and consequent coastal armoring.

The central area of the City’s coast possesses a sandy beach, but the northern and southern ends are eroding such that there is no dry sand beach much of the year. Coastal armoring also exists at the northern and southern ends of the City that exacerbates the beach erosion issue.

Sand historically came from San Juan Creek to naturally nourish San Clemente’s beaches, but this sand supply has been significantly reduced, and the coastline is narrowing in response. A rough estimate is that the City is in need of up to between 5 and 7 million cubic yards of sand to fully restore its shoreline from the north end to the south end. Restoring the City’s beaches may take multiple decades to accomplish and is heavily dependent on funding availability.

The Plan and Solutions
As a result, the City seeks to widen beaches and increase resilience now and for future sea level rise conditions. Numerous studies have identified problems along this coast, so the City plans to study, then design and implement nature-based sand retention solutions as a supplemental strategy to beach sand replenishment, and to ultimately establish living shorelines as dunes along widened beaches.

The City is working intentionally to restore the beach and central to the City’s efforts is completing this Nature-Based Feasibility Study (NBFS) to determine phased options to accelerate the process of beach recovery. The NBFS is intended to identify how to address narrowing shorelines with natural approaches and hybrid approaches that are grounded in designing or engineering with nature. Parallel to these beach restoration efforts is renewed monitoring of the shoreline for beach widths and elevations within the City and the greater south Orange County region. Data from the monitoring program identifies where shoreline narrowing is most acute and determines trends in the shoreline over time and space that informs this NBFS.

In 2023, the City identified critical erosion hot spot sites based on the monitoring results. The sites most critically eroded are the north and south ends of the City. Specifically, Capistrano Shores in the north, Mariposa Point, and Cyprus Shore in the south are most critically eroded shoreline sections in the City. Shorecliffs, North Beach and Linda Lane through the Pier Bowl and T-Street are threatened. Remaining beaches are relatively more stable at this time.

This project aims at identifying ways to stabilize the City’s beaches that are classified as critical and/or threatened. The primary design criteria are to: 1) increase resilience, recreation, economic vitality and habitat, 2) prove the concept through performance metrics, and 3) render it applicable to other locations.

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The City hired a multi-disciplinary team of expert coastal engineers, scientists, ecologists, and economists to collaborate and develop feasible nature-based sand retention design concepts. A broad range of possible solutions were identified by the team and included nourishment as the foundation of the program, sand retention, and living shorelines (sand reserve/sand dunes). The initial range of design concepts were varied and were vetted to the public on multiple occasions in 2023 and 2024. The public opinion also varied but the majority of the feedback the City received stated a preference for sand retention features that are oriented parallel to shore, such as breakwaters. Groins were not widely identified as a preferred strategy. This preference fits the condition of the coastal conditions in San Clemente as sand moves in both directions alongshore over the year favoring shore-parallel versus shore-perpendicular devices for optimal sand retention benefits. The community did not wish to be a testing ground for non-proven devices so there are currently no experimental sand retention design concepts in the NBFS.

The three phases of City work consist of Phase 0 with beach nourishment, Phase 1 with beach nourishment and sand retention, and Phase 2 with living shoreline establishment. Each phase is described below.

Project Phase 0
In 2024, the City initiated the first major efforts to begin public beach restoration. This study refers to beach sand replenishment in San Clemente as Phase 0. Phase 0 nourishment includes pursuing all possible options for placing sand on the beach. These include: 1) the U.S. Army Corps of Engineers 50-year project which placed 200,000 cubic yards of sand near the Pier in 2023-2024 and will repeat every 5 to 6 years through 2074), 2) the Sand Compatibility and Opportunistic Use Program (placed 37,000 cubic yards of sand at North Beach in 2024), 3) San Diego Association of Governments may build a third Regional Beach Sand Project to potentially place up to 1,050,000 cubic yards in the future, 4) the Orange County Transportation Authority planning to place 540,000 cubic yards in the near future, and other projects are in the preliminary planning stages with other local agencies. All of these planned beach sand replenishment projects will function to offset the sand deficit.

Project Phase 1
Phase 1 concepts were developed that provide multiple or co-benefits. Capistrano Shores is the proposed site for a submerged breakwater with beach nourishment, North Beach is proposed for a multi-purpose emergent breakwater with beach nourishment, and State Beach is also proposed for a multi-purpose emergent breakwater with beach nourishment. The multi-purpose emergent breakwater concepts are conceived to double as surfing amenities. This study is focused on sand retention feasibility options, and Phase 1 sand retention strategies aim to support nature-based projects that will be explored in Phase 2 of this overall effort.

Project Phase 2
Phase 2 would consist of establishing living shorelines (vegetated dunes) behind the beach after beaches widen sufficiently to sustain dunes as a sand reservoir. This study assesses whether dunes existed along this shoreline in the past, conditions that make the proposed project sites favorable to dune formation after beach widening, and whether dunes can persist during future sea level rise.

Results of the Study
This NBFS presents the draft concepts and then analyzes each for feasibility. The analysis considers their performance, economics, permitability, and adaptability. Preliminary modeling for Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente xii
performance at retaining sand was done using empirical methods developed for SANDAG and by modeling done on similar concepts for Oceanside. Economics were analyzed for benefits versus costs. Permitability was determined using the combined experience of the team, and adaptability was assessed by the engineers.

Results described in the NBFS show that all concepts perform well to slow alongshore movement of sand. The largest beach forms behind the Capistrano Shores submerged breakwater, while slightly smaller ones form behind both multi-purpose emergent breakwaters. Each beach is prefilled with sand to over-flow the compartment along the shore behind the structure so that no impacts will occur to downcoast beaches from sand trapping.

Costs are greater for the multi-purpose emergent breakwaters than the submerged breakwater, and benefits tend to be highest at North Beach compared to the other two sites due to the proximity of parking, restrooms, refreshments, ease of access and overall beach attendance/visits. For this reason, the North Beach Multi-Purpose Emergent Breakwater is ranked highest of the three concepts.

Following completion of the NBFS in late 2025, the next step is to secure funding to conduct additional design and modeling studies to optimize the project design in an effort to reduce costs and optimize function. Numerical modeling using computer models will determine the concept’s performance in greater detail and the evolution of the City shoreline over time. It will also be valuable to model the concept in a physical laboratory.

Recommended next steps include design and modeling, followed by environmental review, permitting, final engineering for construction and ultimate construction/implementation.

Implementation of the project may require up to 5 years depending on funding availability and City priorities. Reestablishment of the City’s beaches will provide increased shoreline protection for all infrastructure and amenities as well as enhanced recreational opportunities and related economic benefits. The City remains on the forefront of innovation to protect its valuable beach resources and will set the trend for other jurisdictions to follow.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 1 1. Introduction
This document is a Final Feasibility Study prepared for the City of San Clemente (City) that examines several design alternatives to promote long-term resiliency along the City shoreline using nature-based strategies to the greatest extent, including designs using natural materials (sand, cobble, stone, vegetation). San Clemente is a beach town that has experienced widespread beach erosion and retreat since the early 2000s due to historic natural sand supplies being cut off and no longer reaching the beach. Existing beach widths have narrowed enough to become problematic for infrastructure backing the beach and have reduced public recreational use of the beaches in the City.

A wide variety of traditional shore parallel and shore perpendicular engineering solutions are available to reduce coastal erosion. The range of solutions includes both structural (i.e., grey) and soft (i.e., green) types of solutions as well as hybrid green-grey solutions which combine elements of both green and grey designs.

All feasible nature-based coastal resiliency solutions were considered for application along in San Clemente coastline. Initially some innovative, novel and new concepts were included in the range of alternatives proposed for consideration in the City. However, the range of solutions were narrowed through an iterative public review and comment process to three design concepts described in this Final Report. In general, the community expressed a preference for more traditional and proven approaches to build resiliency used elsewhere in Southern California and less of a desire to be a testing ground for new concepts.

This Nature-Based Adaptation Project Feasibility Study is partially funded by a California Coastal Commission (CCC) Local Coastal Program (LCP) grant awarded to the City in 2022. Building long-term coastal resilience in San Clemente is a top local priority of both the City Council and the community at large. The current report builds on the City’s Coastal Resiliency Plan (City of San Clemente 2021) which was built upon the San Clemente Sea Level Rise Vulnerability Study (Moffatt & Nichol 2019).

The State of California encourages green or soft, nonstructural and hybrid solutions to be prioritized over grey solutions wherever possible to promote resilience The CCC issued a staff report in 2021 that expressed their interest in projects incorporating non-traditional nature-based solutions (NBS) to increase coastal resiliency (California Coastal Commission 2021). State guidance came out in September of 2025 addressing use of nature-based approaches.

Nature-based approaches are defined as: A coastal adaptation and/or erosion control method that is comprised of natural or mostly natural elements, which contributes to the persistence and enhancement of coastal processes and ecological benefits while also protecting inshore areas.

The guidance states, “By using natural elements, nature-based adaptation strategies ideally seek to mimic and enhance natural systems and processes to address erosion and other related hazards while at the same time supporting the ecological benefits provided by natural habitats. In encouraging the use of nature-based adaptation solutions, the Coastal Commission can continue to carry out its duty to protect public interests on the coast while helping coastal communities remain resilient to sea level rise”. The guidance further states, “Nature-based adaptation strategies may also be an important component of phased adaptation approaches, particularly in the short- to medium-term. Phased adaptation should include consideration of how a variety of nature-based adaptation projects can fit in with other site-specific and regional resiliency efforts to employ a more holistic planning approach” (California Coastal Commission 2025).

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 2 With regards to their status according to review and approval by the Coastal Commission, the 2025 guidance further states this: The Commission defines a nature-based adaptation strategy as a coastal adaptation or erosion control method that primarily relies on natural elements to enhance coastal processes, provide ecological benefits, and offer protection to inshore areas.

These strategies exist along a spectrum, ranging from soft approaches that use dynamic natural systems, such as dune or wetland restoration, to hybrid armoring that integrates structural elements with nature-based features. However, there are no set criteria for determining the extent to which a project qualifies as a nature-based adaptation strategy. Some projects may be labeled as nature-based adaptation strategies while still incorporating elements of hard armoring, which can diminish their ecological value and introduce concerns regarding shoreline access and habitat loss. A project's classification as a nature-based adaptation strategy does not change the standard of review, and decisionmakers should look beyond the label assigned by an applicant to ensure that, to the extent feasible consistent with project objectives, nature-based adaptation projects genuinely integrate natural features, contribute to measurable habitat enhancement or restoration, and align with community priorities (California Coastal Commission 2025).

And finally, the Commission indicates that the proponent needs to be mindful of the following:

While nature-based adaptation strategies are often considered a less environmentally damaging alternative to hard armoring, the project applicant must demonstrate that a proposed project is consistent with all relevant Coastal Act and LCP policies, including that it appropriately minimizes risks to life and property, and is the least environmentally damaging feasible alternative.

Applicants should identify current and future coastal hazards that the proposed project aims to minimize, including with respect to expected sea level rise over the anticipated life of the project.

This information will also be relevant to the extent that the proposed project is a component of a longer-term coastal resilience planning effort (California Coastal Commission 2025).

The present study aims to evaluate both traditional and some innovative nature-based pilot project strategies in San Clemente that may also serve as examples to other areas in southern California.

Sandy beaches provide benefits of shoreline protection (soft/green), public recreation and habitat.

The loss of beaches means the loss of these benefits as well as economic contributions to a strong local and regional economy, which negatively impacts the region as a whole.

The CCC defines NBS as strategies that harness the power of nature to address societal challenges, including climate change, disaster risk reduction, and biodiversity loss, while simultaneously benefiting people and nature. The CCC encourages the use of "softer" solutions, such as restoring natural ecosystems (like beaches, dunes and wetlands) over "hard" infrastructure which have the potential to affect coastal resources. More information regarding the green approach is provided in Section 3 of this report.

1.1. Background and Statement of the Problem
San Clemente is a coastal City situated at the southern end of Orange County, California. Figure 1-1 shows the location of the City within south Orange County, and the extent of the City along the shoreline. It is bordered by the City of Dana Point to the north and by Marine Corps Base Camp Pendleton/San Onofre State Park (in San Diego County) to the south.

There are approximately 4.9 miles of coastline within the City’s coastal jurisdictional boundaries.

Of the shoreward property parcels along this coastline, the largest portion of 1.9 miles is City owned, 1.15 miles are State owned (California Department of Parks and Recreation or State Parks), and 1.65 miles are privately owned out to the mean high tide line (MHTL).

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 3 The primary source of sediment to the beaches of the City has been from San Juan Creek located to the north. Due to urbanization and upstream water supply management actions, this Creek delivers less sand to the beach now than in the past. Other historic sources of sand were sand moving around Dana Point and moving south toward the City, but that source is non-existent with the intercepting Harbor breakwater structure in place. Construction of Dana Point Harbor yielded sand to the coast as a byproduct, but that source was limited and no longer provides benefits.

San Mateo Creek and potentially even the Santa Margarita River may have provided sand to this coast historically, but they do not serve as significant sand supplies to the coast at (Patsch and Griggs 2007). With historic sources of sand no longer available to the coast, beach erosion has continued downcoast of the Harbor and extends to the San Onofre State Beach south of the City.

A critical erosion hot spot analysis was conducted as an early task of this project and results are summarized within Section 2 this study, showing several City beaches in the critically eroded condition.

In addition, coastal armoring has occurred at various locations in response to the narrowing of the beaches. Armoring exists all along Capistrano Shores, Mariposa Point, and Cyprus Shore. It occupies sand beach footprint and prevents bluff erosion from supplying sand to the littoral cell.

This could have contributed to the inability of the beaches to naturally recover during periods of opportunity. These effects are all compounded as sea levels rise.

Therefore, the main coastal problem experienced within the City is coastal/littoral sediment deficit conditions, so insufficient sand exists along the shoreline resulting in increasingly narrow beaches and responses of coastal armoring. There are some areas of sandy beaches within certain areas of the City (approximately between the Pier and Calafia State Beach), but they are limited in area and seasonally narrow too. The majority of the City shoreline is narrow and actively retreating.

Sandy beaches provide the benefits of shoreline protection to infrastructure on and behind the beach, recreational play area on the beach, habitat on and within the sand on the beach, and sources of local and regional economic revenue. The identity of the City is centered on the beach (e.g., Surf City). Without a beach, the City’s fundamental character and historic beach-related function ceases to exist. Figure 1-2 is a historic map of the City’s shoreline from 1886 that shows a beach along the entire City location with the exception of the south end near the present location of Cyprus Shore. Figure 1-3 and Figure 1-4 show historical aerial images from May of 1960 of the north and south halves of the City, respectively. These are prior to Dana Point Harbor being constructed and associated beach nourishment, so it should represent a more “natural” condition.

They show a “walkable beach” from one end of the City to the other. A beach exists all along the City that is not necessarily very wide, but it exists in the form of a high, dry beach, and the photos reflect a post-winter beach condition when the beach should be at its narrowest.

Figure 1-4 and Figure 1-5 show more recent examples of existing narrow beaches at the north and south ends of town that threaten critical public infrastructure. As a note, the City’s public safety building (formerly a concession building) lost its north railing due to a partial perimeter walkway undermining/collapse in March of 2025 during preparation of this report.

The City is taking action to solve this problem by working to conduct beach sand nourishment and sand retention to counteract the sediment deficit and eventually create living shorelines (dune habitats along the rear of the beach). Examples of such actions are listed in Section 1.3 of this report below.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 4 Figure 1-1: Regional Location of the City of San Clemente and Local Landmarks Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 5 Figure 1-2: Historic Shoreline Map of the City of San Clemente Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 6 Figure 1-3: Historical Aerial (1960) of the North End of the City of San Clemente (Capistrano Bay District to Linda Lane Just North of the Pier) Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 7 Figure 1-4: Historical Aerial (1960) of the South End of the City of San Clemente (T Street South of the Pier to San Mateo Point)
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 8 Figure 1-5: North Beach Near the North End of the City in the 1993 (Bottom) in the Early 2019 (Top) Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 9 Figure 1-6: Cyprus Shore at the South End of the City in 2014 (Bottom) in 2020 (Top) Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 10 In 2021, the City initiated a process to identify feasible solutions to promote long-term resiliency of its shoreline by retaining and reducing the loss of sand that occurs along its coast. The City has a certified Local Coastal Program (LCP) and Land Use Plan (LUP) which was approved by the CCC on August 10, 2018. In addition, the City completed a Sea Level Rise Vulnerability Assessment (SLRVA) that was submitted to the CCC in December 2019, and a Coastal Resiliency Plan which was submitted to the CCC in December 2021.

The City has also published a public review draft LCP Implementation Plan (IP) which was submitted to the CCC in April 2022 as a final deliverable for a CCC Round 5 LCP Planning grant.

The IP remains in draft form. Each of these coastal planning documents have been facilitated in part by LCP Planning Grants awarded to the City.

Completion of the LUP, SLRVA and the Coastal Resiliency Plan represent the beginning of the phased adaptation efforts to advance coastal resiliency in the City. These documents outline a path forward for the City to address sea level rise by reducing risks and exposure to coastal hazards. The City’s coastal resiliency planning efforts are ongoing as the understanding of the variables involved in climate science, including greenhouse gas emissions scenarios and sea level rise (SLR) predictions, continues to improve.

1.2. City Goals and the Purpose of This Study
This study is focused on clearly defining existing problems and identifying effective solutions to restore and build long-term coastal resilience in San Clemente. Beach nourishment provides the most direct solution as it increases the supply of sand to the shoreline to widen the beaches and create living shorelines. Beach nourishment is included in the approaches to re-establish and widen the beaches as specified in Section 1.3 below. The City also needs to retain the sand that is being placed to preserve the benefits longer and to reduce maintenance/renourishment cycles.

Also, nourishment alone may not accomplish the desired end unless done in very large quantities.

The vision is to eventually have wide beaches with living shorelines along the rear of most beaches, with increased recreational beach area and lateral coastal access available to the public.

Specifically, the City considered the ultimate quantity of sand that might be needed to widen beaches sufficiently to protect the backshore during the 100-year coastal storm event. For a similar condition along San Diego County, the San Diego Association of Governments (SANDAG) used a beach width of 200 feet plus 50 feet for seasonal beach width changes, or 250 feet total to fully protect against that storm (SANDAG 1993).This study for San Clemente assumed the same target width and calculated that providing that width would require between 5 and 7 million cubic yards of sand to fully protect San Clemente from one end of the City to the other. This ultimate condition would be a future condition accomplished by multiple projects over time adding sand incrementally. Understanding that this vision or goal is into the future and may or may not ever be fully realized, the City is looking at ways to optimize the performance of nourishment with retention structures to hold sand in place longer, thereby maintaining wide beaches and eventually enabling colonization of living shorelines. Wide beaches with living shorelines provide the greatest level of protection along the back of the beach and maximize recreational and habitat benefits.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 11 This Feasibility Study is focused on Project Phase 1, Sand Retention with Beach Sand Nourishment, with the intent of initiating Project Phase 2, Colonizing Living Shorelines. Its origin dates back to another State funding grant award after completion of the planning documents mentioned above. In March 2022 the City received notification of a fourth LCP Planning Grant (i.e., a CCC LCP Round 7 Grant) to support continued coastal resiliency building efforts in the City. The focus of this latest grant funding is the advancement of key recommendations in the Coastal Resiliency Plan which include re-establishment of a shoreline monitoring program and development of one or more nature-based shoreline management projects. A key City goal is the protection of the public beach which serves as a natural shoreline protective buffer that supports a sustainable, healthy and resilient environment for the local community, tourism, and wildlife.

The community has advocated for a walkable sandy beach, regardless of tide, throughout the City, so achieving that objective is one of the goals of this study.

The focus of this project is Task 2 of the City’s Round 7 CCC LCP Planning Grant in the preparation of a Feasibility Study focused on identification of critical erosion hot spots and opportunities to develop nature-based pilot project(s) that provide multiple benefits (e.g., sand retention, recreation, and ecosystem benefits, etc.). The City desires to identify one or more coastal resiliency pilot projects and/or strategies that are environmentally thoughtful, financially feasible and that can be approved through the regulatory permitting process.

This project was initiated in November 2022 and has an expected completion timeframe of November 2025. The project team performed ecological reconnaissance of the City’s shoreline to map coastal ecological resources. These data, in conjunction with data from a shoreline width monitoring program and resident interviews, was used to develop a “Critical Erosion Hotspots Memorandum” (Moffatt & Nichol 2023) that is published on the City website. This memo describes the City shoreline based on areas of erosional trends and identifies which “reaches,” or discrete segments, of coastline are most in need of coastal resiliency interventions.

The project team used the information from this report to select proposed project locations and draft conceptual pilot project ideas designed to promote sand retention and living shorelines along the beach for each reach of the shoreline. These were developed with the goals of preserving or enhancing existing resources (e.g., recreational, infrastructural, ecological, economic, etc.) at each location. The proposed project locations are Capistrano Shores, North Beach, and State Beach due to the need, benefits, and results of community input.

Conceptual ideas were presented to the local community multiple times during a one year long, iterative outreach and engagement process from July 2023 through July 2024. Meetings with the general public at City Hall in 2023 and 2024 presented conceptual graphics that were refined based on input from the stakeholder focus groups. The meetings were conducted with the goal of garnering additional feedback and opinions from the public on concepts that were to be incorporated into concept refinement carried forward to the next phase of the study.

A Draft Design Concept Memorandum was presented for public review in August of 2024 that serves as the basis for this report. The memo was the first iteration of the effort to refine and identify those concepts that are considered for advancing to the next phase of the Study which would include design, numerical and physical modeling, environmental review and permitting tasks.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 12 In addition to the community meetings, the City team also met with other identified stakeholders, groups and representatives including the Orange County Transportation Authority, Surfrider Foundation, Bring Back Our Beaches community group, Save Our Beaches community group, the North Beach Community Association, and the Capistrano Shores Homeowners Association.

Sessions of individual stakeholder meetings were conducted in July-August 2023 and in June 2024 to obtain feedback for refinements prior to the September 2023 and July 2024 public meetings.

1.3. Related City & Regional Coastal Resiliency Building Efforts Several other efforts to increase coastal resiliency are occurring within the City and the region that are being coordinated with adjacent jurisdictions and other public agencies with landowners and management responsibilities. The first is an ongoing, annual shoreline monitoring program conducted by the City of San Clemente on behalf of the region consisting of fall and spring beach/shoreline profile transect surveys. These “beach profile surveys” document the condition of the City’s public beaches and establish baseline conditions against which future sea level rise effects can be quantified. The City had done this work in the past and re-established it as part of the 2022 Grant award. The shoreline monitoring effort that commenced in Summer 2022 is Grant Task 1 and will continue through December 2025.

Regarding beach nourishment, the City is currently in Phase 0 of Beach Nourishment Efforts in 2024 and beyond. These beach nourishment efforts include those listed below and shown in Figure 1-7:

1. U.S. Army Corps of Engineers (USACE) 50-Year Project (251,000 cubic yards, of sand every 5-6 years, depending on federal government funding) that started in 2023/2024;

2. San Diego Association of Governments (SANDAG) Regional Beach Sand Project III with Orange County Parks and Dana Point (the City requested 1,050,000 cubic yards of sand total) planned for approximately 2030-2035;

3. Orange County Transportation Authority (OCTA) planning to deliver 540,000 cubic yards of sand total within the near-term. The CCC approved emergency placement of 240,000 cubic yards of sand near Mariposa Point in April 2025 (Reinforcement Areas 1 & 2);

4. City of San Clemente Sand Compatibility and Opportunistic Use Program (SCOUP) with 37,000 cubic yards of sand placed at North Beach from the Santa Ana River in JulyOctober of 2024, and

5. The OC Parks South Orange County Regional Coastal Resilience Strategic Plan that includes a SCOUP that yielded 20,000 cubic yards of sand placed upcoast in Capistrano Beach July-October of 2024 that could eventually supplement San Clemente beaches.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 13 Figure 1-7: Phase 0 – Current and Planned San Clemente Beach Nourishment Projects Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 14 A brief explanation of these projects is below for clarification. The maximum cumulative quantity of sand that these projects could supply to the City shoreline is 7,100,000 cubic yards which is sufficient to offset the estimated sediment deficit within the City.

Beach Nourishment Project 1 is the City and USACE 50-year beach nourishment program project that was implemented in late 2023, with renourishment planned to occur every six years, depending on the status of the appropriation of federal funding. It centers on the Pier Bowl beach area with the Pier near its centerline. The first placement occurred in 2023/2024, and 200,000 cubic yards of sand was placed. This project could provide up to 2,510,000 cubic yards of sand total over 50 years.

Beach Nourishment Project 2 is the SANDAG RBSP III. SANDAG is the Metropolitan Planning Organization (MPO) for the San Diego region and plays a key role in the regional coordination of a variety of projects. SANDAG previously completed two regional beach sand projects (RBSPs) in 2001 and 2012 (RBSP I and RBSP II, respectively), adding approximately 3.5 million cubic yards of sand to the San Diego region's local beaches. Several offshore borrow sites along the San Diego coastline were used to nourish twelve different receiver sites for RBSP I, with a total of 2.1 million cubic yards of sand. RBSP II resulted in 1.5 million cubic yards of sand being placed on eight different beaches in 2012. These projects were initial pilot projects, representing the first major step in addressing the severe sand deficit on the region’s beaches and identifying a long-term approach to managing the region’s shoreline.

Due to the continued sand deficit within the littoral system, a third RBSP project is currently under consideration and is being evaluated for its feasibility. As a part of RBSP III, an expanded nourishment plan is proposed that encompasses the entire Oceanside Littoral Cell and extends north to include the evaluation of nourishing south Orange County beaches in the Cities of Dana Point and San Clemente. This is the first time beaches outside of San Diego County would be included as part of an RBSP project. Three footprints in Orange County are proposed: San Clemente State Beach, North Beach, and Dana Point. Approximately 250,000 cubic yards of sand is proposed to be placed on North Beach, up to 800,000 cubic yards of sand is proposed to be placed on San Clemente State Beach, and 500,000 cubic yards is proposed for Dana Point for 1,550,000 cubic yards total. This would add a significant amount of sand into the littoral cell and increase the resiliency of beaches with the City. This project may occur near 2030.

Beach Nourishment Project 3 is the OCTA 540,000 cubic yards nourishment project associated with their near-term resilience efforts to protect the railroad right of way over the next 30 years.

The OCTA proposed to place sand along the south end of the City, in the vicinity of the toe of an active landslide threatening the Cyprus Shore community of San Clemente, and along the Mariposa Point reach of the shoreline. Both sites represent actively threatened reaches of the railroad by flooding from waves. The date of this project is not specified but the CCC approved placement of 240,000 cubic yards of sand in April 2025 under an Emergency CDP issued for OCTA Reinforcement Areas 1 & 2 along Mariposa Point. Sand placement at Reinforcement Area 4 along Cyprus Shore is planned for 2027.

Beach Nourishment Project 4 is the City SCOUP that is intended to capitalize on opportunities for truck haul deliveries of sand as it becomes available as a byproduct of upland development and flood control maintenance projects. This project provided sand to the City in 2024 as an extension of a previous program that also fed the City with sand in 2005 and 2016. This program could result in 300,000 cubic yards of sand placed every year for 10 years, or 3,000,000 cubic yards of sand total.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 15 Beach Nourishment Project 5 is the Orange County effort to increase resilience in the form of their regional strategic plan for South Orange County. This plan includes a SCOUP that resulted in sand being delivered to an upcoast beach in 2024 from the same Santa Ana River source that nourished the City.

These efforts are coordinated by the City, and their combined benefits should lead to more sand along the City and wider beaches. A total of 7,100,000 cubic yards of sand could potentially be placed over time with these projects if they all occurred to their possible maximum quantities. As such, their cumulative benefits may be sufficient to eventually offset the loss rate of sand along the beach and stabilize the shore, but that projection may be premature and is not the only tool the City wishes to employ to combat the problem. Besides, sand placed as nourishment will disperse over time and space depending on sand gradation and wave conditions, with much remaining within the City’s littoral zone, but some may move outside of the City and even out of the littoral zone over time. Thus, the projects presented in this Feasibility Study are presented as the next wave of actions to stabilize the shore and create and maintain more beaches.

The following section of this document presents existing conditions as the basis for developing alternative concepts to carry forward.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 16 2. Existing Conditions
Existing coastal conditions are presented below for background and context of beach erosion problems within the City.

2.1. General Shoreline Conditions Within the City and South Orange County The City is located within south Orange County, specifically in the Capistrano Bight, which is bound by the Dana Point headland to the north and San Mateo Point to the south. The Capistrano Bight is a subtle embayment between the two headlands. Processes with this Bight are explained using the concepts of the littoral cell and the sediment budget, as supported by data of the shoreline position over time and evidence of erosion.

2.1.1. The Littoral Cell
Capistrano Bight lies within the northernmost reach of the Oceanside Littoral Cell. A littoral cell is the zone of sand inflow, movement, storage, and outflow along the shoreline and shallow ocean within a bounded geographic area. The Oceanside Littoral Cell extends from Dana Point south to Point La Jolla and is broken into two sub-cells by the Oceanside Harbor breakwater. Figure 2-1 shows the Littoral Cell and place names within that cell (Patsch and Griggs, 2023).

Several studies estimate the sediment budget and movement patterns of material within the Oceanside Littoral Cell on a broad scale (USACE 1990) (USACE 1991); (Patsch and Griggs 2007). The USACE found that net annual littoral transport within the northern sub-cell of the Oceanside Littoral Cell is from generally north to south over time. On a very broad scale, sand movement varies over time and space, but the rough magnitude of gross longshore sand transport is 800,000 cubic yards per year moving in both directions, with the net transport magnitude being up to 150,000 cubic yards and moving to the south (USACE 1991). A more recent study suggests the net longshore sand transport patterns may be more complex on a smaller scale and may be south to north over certain periods of time, with significant variation seasonally (Kahl, et al. 2024).

Studies by the University of California at Irvine suggest that the direction of sand movement splits and heads in opposite directions at San Mateo Point (Kahl, et al. 2024). Divergence of net annual sand transport may occur at this location with intensified northward drift just north of the point and increased southerly drift just south of the point. This infers that sand may move north into the City from the south, and also move into the City from the north.

This convergence of sand into the City would signal good news and sand storage on beaches, and that appears to occur between the Pier and the State Beach where beaches are widest.

However, the quantity of sand moving into the City over time from either direction is still insufficient to maintain wide beaches outside of this central area, so the sand supply is still short and leading to erosion. For example, a critical erosion hotspot memorandum (Moffatt & Nichol 2023) identified the southern shoreline reach of the City to be in critical condition due to its minimal beach width, so sand input from the south is apparently not being stored at that beach.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 17 Figure 2-1: Oceanside Littoral Cell, Northern Sub-Cell (Patsch and Griggs 2023) Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 18 2.1.2. The Sediment Budget
The sediment budget is a concept that clarifies the relationship between sand supply rate to the shoreline, the storage volume along the shore, and the sand loss rate away from the shore. This relationship between sand input, storage, and output defines whether a beach exists or not, and whether that beach is wide or narrow. More sand supplied to a shore relative to sand lost creates a beach, whereas less sand supplied to a shore relative to that lost leads to erosion. Beaches are the storage areas for the sand as it moves along the shore from source to ultimate destination.

Wide beaches represent more sand storage than narrow beaches. Beaches are typically transitory and very dynamic, but the basic premise of supplying more sand to a beach while reducing sand lost from that beach describes building and maintaining beaches.

Material from San Juan Creek is believed to be the most significant historic source of sediment to the City shoreline (Patsch and Griggs 2007). Other important watersheds exist within the northern sub-cell of the Oceanside Littoral Cell that could conceivably supply sand to the City, such as the Santa Margarita River and nearby San Mateo Creek. All of these sediment sources may feed sand to the City, but the historic sediment yields have declined over time.

During the construction of Dana Point Harbor, 2.4 million cubic yards of sandy material were excavated from the existing harbor location and placed on Doheny and Capistrano Beaches (Figure 2-2). This added a substantial amount of sand to the littoral cell and likely created artificially wide sandy beaches that otherwise would not have naturally occurred. Due to the lack of nourishment in the Capistrano Bight since the construction of the harbor, the coastline has experienced consistent narrowing throughout the region.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 19 Figure 2-2: Doheny Beach Shoreline Pre- and Post-Construction of Dana Point Harbor Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 20 Patsch and Griggs (2007) estimated the sediment budget is at equilibrium between Dana Point and Oceanside Harbor (the entire northern sub-cell of the Littoral Cell) with an input of approximately 290,000 cubic yards per year canceling out the loss of sediment to its sinks (~290,000 cubic yards per year), resulting in a relatively stable coastline overall. Beach nourishment was estimated to provide approximately ~110,000 cubic yards per year, fluvial sediment approximately ~80,000 cubic yards per year, and sediment from sea cliff and upland erosion approximately ~69,000 cubic yards per year, and gully and upland terrace erosion for ~31,500 cubic yards/year in this part of the littoral cell (Patsch and Griggs 2006). Sediment losses were attributed to transport into the Oceanside Harbor (146,000 cubic yards per year) and a sandbar offshore of the Oceanside Harbor mouth (144,000 cubic yards per year).

As part of the feasibility study for the USACE’s San Clemente Beach Nourishment Project which started construction in December 2023, the USACE conducted a historic sediment budget analysis for three different time periods from 1900-1990 (USACE 2012). The sediment budget indicated that the shoreline was generally at an equilibrium with certain locations retreating and others advancing.

A 2014 characterization of the coastal and hydraulic/hydrologic processes at Doheny State Beach provided an assessment of littoral sediment transport patterns and a sediment budget for the coast between Dana Point and San Mateo Point (Coastal Environments 2014). Data were aggregated from sediment studies spanning the 1980s to the 2000s, and it was estimated that the sediment budget for the region is -56,000 cubic yards per year (erosion) in dry years, and a +3,000 cubic yards per year surplus (accretion) in wet years. The difference in sediment yields between this study and those mentioned above are likely due to comparatively little artificial nourishment taking place in the Capistrano Bight from the 1980s through the 2010s. In contrast, major beach replenishments sourced from the construction of Dana Point Harbor in the 1960s likely offset some of the net erosion that would otherwise have taken place in the cell. The discrepancy in sediment yield between wet and dry years calculated by the Coastal Environments 2014 study helps explain why the prolonged drought over the late 2010s to early 2020s was correlated with significant shoreline erosion from Dana Point through San Clemente.

Most research indicates that net littoral drift and sediment transport in both the northern and southern sub-cells in the Oceanside Littoral Cell is generally from north to south. This is supported by anecdotal data of sand accumulation within the area, such as north of T Street Reef in the City, and the north side of Doheny groin at the San Juan Creek mouth. However, with direct exposure to southern hemisphere swells, the northern sub-cell—particularly the zone from San Clemente through Doheny State Beach—experiences a strong seasonal signal of northward transport from May through October. Kahl et al. (2024) indicates that from Oceanside Harbor to San Onofre the net littoral transport may be northward year-round based on wave and shoreline data from 2000 2021, while the coastline from San Onofre to Dana Point exhibited several reversals of net transport direction.

To summarize, the causes of reduced sand supply include:

1. Less sand from the rivers due to flood control improvements (damming, channel lining, weirs, etc.);

2. Less sand from bluffs due to development and coastal armoring (shore protection for residential developments and the railroad);

3. Lack of nourishment since the 1960s (Dana Point Harbor and San Onofre Nuclear Generating Station installations), and
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 21 4. Significant drought years occurred throughout the 2000’s reducing natural sand supply.

In addition, significant storm wave events occurred in the years 1997-1998, 2014, 2016, and 2023 further increasing erosion without the shoreline’s ability to recover.

The fate of sand from San Clemente is difficult to discern but the most likely destination has been to the south along Camp Pendleton where a 5 mile-long sand deposit (fillet) has formed upcoast of Oceanside Harbor impounding nearly 3-5 million cubic yards of sand (Everts 1994) since it’s installation in 1942 and expansion multiple times afterward in the 1943, 1958, 1961, and 1994 (Moffatt & Nichol 1994).The sand lost from San Clemente may also have simply been lost over time offshore into deeper water during extreme winter storm wave events that cannot return in the summer.

San Clemente has participated in coordination with neighboring jurisdictions including the County of Orange, City of Dana Point, California State Parks, and the Orange County Transportation Authority. The County of Orange developed a South Orange County Regional Strategy that includes all of these partners (County of Orange 2024). In addition, the City has aggressively approached the San Diego Association of Governments to be added to the SANDAG Regional Beach Sand III project.

2.1.3. The Shoreline Position
Monitoring data of historical shoreline change within the City indicates a shift beginning in the 1980s from a stable shoreline to an average erosional trend (City of San Clemente & Moffatt & Nichol 2019). The two types of data consisting of aerial imagery and beach profile surveys are discussed below regarding shoreline position. Over a larger scale, the majority of the shoreline within the Capistrano Bight has been retreating at an increasing rate since the 1990s according to both data sources.

Aerial Imagery
Aggregated shoreline position data from CoastSat (Vos, et al. 2019), an online tool that utilizes historic satellite data to analyze shoreline erosion trends, clearly indicates this trend of a narrowing shoreline throughout the region since the year 2000 shown in Figure 2-3.

This loss of sediment supply has mostly been attributed to the urbanization of the coastline, channelization of lower creeks/streams, the impounding of sediment upstream within feeder watersheds, and the impounding of material sourced from cliff retreat by infrastructure built seaward of the cliff base throughout the Bight (Patsch and Griggs 2007). However, historical imagery shows that the shoreline within the Capistrano Bight pre-urbanization was not particularly wide anyway, and other sources suggest that under natural conditions certain beaches in southern California only sustained relatively narrow beaches before human intervention (Flick 1993).

Beach Profiles
Shoreline monitoring programs have been conducted intermittently in the south Orange County region since the early 1980s. Ten surveys were performed by USACE between November 1983 and December 1989 under the auspices of the Coast of California Storm and Tidal Wave Study-San Diego Region (CCSTWS-SD); (USACE 1991). Between October 2001 and May 2007, eleven surveys were conducted on behalf of the City of San Clemente Beach Monitoring Program (Coastal Frontiers 2007). Four additional wading-depth surveys were later performed between November 2016 and November 2017 exclusively at North Beach in the City to document the Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 22 placement of opportunistic nourishment. The City of San Clemente Beach Monitoring Program resumed in October 2022, following a nearly 16-year hiatus.

The current City program consists of semi-annual beach profile surveys conducted along up to twelve shore-perpendicular transects with a typical alongshore spacing between transects of less than ½ mile shown in Figure 2-4. The City’s survey covers the entire area from Cotton’s Point to Doheny State Beach.

Five of the transects were established specifically for the City’s program and were surveyed for the first time in Fall 2001 (Coastal Frontiers Corporation 2001). Six transects had been established previously by the USACE and were included in the CCSTWS-SD (USACE 1991).

One additional transect was established in May 2005 to monitor the fate of sand nourishment material placed at North Beach (Coastal Frontiers Corporation 2005). The most current effort is presented in the Beach Monitoring Program Spring 2025 Beach Profile Survey Report (Coastal Frontiers Corporation 2025).

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 23 Figure 2-3: CoastSat Shoreline Transect Trends Along the Capistrano Bight Since 2000 (Vos, et al. 2019) Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 24 Figure 2-4: San Clemente Beach Monitoring Program – Beach Profile Transect Location Map Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 25 Beach profile data are obtained along each transect from the back beach to a location beyond the estimated depth of closure. The surveys are conducted in the spring and fall, corresponding with the beginning and end of the winter and summer wave seasons, respectively. The beach profile survey results are used to assess the shore zone changes and evaluate the impact of natural events (e.g., El Niño) and human intervention (e.g., beach nourishment). Comparison of the spring and fall profiles provides an indication of seasonal changes, while comparison of consecutive fall profiles shows the nature of inter-annual and long-term changes.

The current program incorporates publicly available LiDAR data of the above-water beach to supplement the beach profile data and reduce temporal gaps in data coverage between the aforementioned monitoring programs (Coastal Frontiers Corporation 2024). LiDAR surveys for years 1997, 1998, 2007, 2008, 2009, 2014, 2016, and 2018 are utilized. The data were acquired by a variety of entities, including the United States Geological Survey, the USACE’s National Coastal Mapping Program, and Scripps Institution of Oceanography (National Ocean and Atmospheric Administration (NOAA) 2023). Full spatial coverage of the study area was not available from every LiDAR survey.

Table 2-1 summarizes the beach profile characteristics in nine sub-reaches that encompass the study area. The reaches correspond to those analyzed by Moffatt and Nichol (2023). The berm height was estimated from a representative transect in each sub-reach, while the depth of closure value corresponds to the deepest value among the transects in a given reach. The depth of closure represents the sea bottom elevation at the “statistical range of closure.” This parameter represents the distance seaward of the transect origin beyond which profile variations are smaller than the accuracy of the survey technique and is adopted to separate the signal of true profile change from the noise of survey inaccuracy. The method for estimating the range of closure is provided in SANDAG’s Annual Shoreline Monitoring Reports (Coastal Frontiers Corporation 2024). Furthermore, it is speculated that the range of closure may be underestimated in this region due to the sand-starved nature of the beaches.

Table 2-1: Beach Profile Characteristics in South Orange County Sub-Reaches Sub-Reach Representative
Transect
Berm Height
(feet, MLLW)
Depth of Closure
(feet, MLLW)
Doheny State Beach DB-1850 13 feet -15 feet
Shorecliffs SC-1720 14 feet -15 feet
Capistrano Shores SC-1705 9 feet -14 feet
North Beach SC-1700 13 feet -16 feet
San Clemente City Beaches SC-1695 9 feet -13 feet
Pier Bowl & T-Street SC-1660 14 feet -16 feet
Boca Del Canon Beach SC-1645 14 feet -20 feet
San Clemente State Beach SC-1623 14 feet -14 feet
Cyprus Shore SC-1605 14 feet -17 feet
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 26 The berm height and depth of closure values in Table 2-1 can be used to estimate the loss of beach due to sea level rise using the equilibrium beach profile concept proposed by Dean (1991).

Similarly, beach width gains attributable to adding sand nourishment can be estimated using these values along with grain size information.

As mentioned above, beach profile surveys have been conducted intermittently in the study since the early 1980s (USACE 1991); (Coastal Frontiers Corporation 2024). Surveys typically are conducted in the spring and fall to capture seasonal, annual and long-term changes. Beach widths are computed from the beach profile data as the distance between the landward edge of the beach sand and the point at which the beach profile intersects the plane of the Mean High Water (MHW) datum. More recently, the City of San Clemente Beach Monitoring Program augmented the beach width database using LiDAR data. The results are tabulated in the program reports (Coastal Frontiers Corporation 2024).

Beach width provides an indication of recreational area as well as the protection afforded to upland facilities. Comparison of the fall and spring beach widths provides an indication of winter seasonal changes (typically erosion at southern California beaches), while comparison of spring and fall beach widths shows summer seasonal changes (typically accretion at southern California beaches). Consecutive fall beach widths show the nature of inter-annual and long-term changes.

Table 2-2 summarizes the beach width changes and trends documented in nine sub-reaches within the study area between 2001 and 2025. Several beach nourishment projects were conducted during this period. Two small projects occurred at North Beach with 5,000 cubic yards in 2005 and 12,000 cubic yards in 2016, respectively, and the USACE project of 200,000 cy occurred in near the pier 2023/24 while the County placed 37,000 cy on North Beach in 2024..

At the time of the Spring 2025 survey, the beach width among the nine sub-reaches ranged from 185 feet at the T Street sub-reach to 16 feet at the Capistrano Shores sub-reach. The beach width was less than 100 feet at three sub-reaches (Capistrano Shores, San Clemente City Beaches, and Cyprus Shore). The width of the beach did not exceed 200 feet anywhere. When the 23-year period between the Fall 2001 and Fall 2024 surveys is considered, net beach gains prevailed at four sub-reaches in the central portion of the region (Capistrano Shores – though minimal, San Clemente City Beaches, Pier Bowl & T-Street, and Boca Del Canon Beach). Net beach width losses were sustained at the remaining five sub-reaches — each located at the northern or southern extents of the City. This outcome reflects shoreline change rates ranging from accretion of 2.2 feet/year (Pier Bowl & T-Street) to erosion of 6.2 feet/year (Cyprus Shore).

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 27 Table 2-2: Beach Width Changes in South Orange County Sub-Reaches, 2001 to 2024/2025 Sub-Reach
Spring 2025
Beach Width
(feet) 1
Beach Width Change
(feet) 1
Fall 2001-Fall 2024
3 Beach Width
Trend
(feet/year) 1,2
Fall 2001-Fall 2024
3 Doheny State Beach (South
to North) 117 to 129 -105 -3.9
Shorecliffs 154 -8 -1.4
Capistrano Shores 16 2 -0.6
North Beach (North to
South) 105 to 132 -39 -0.8
San Clemente City Beaches
(Dije Court) 25 8 -0.3
Pier Bowl & T-Street 74 to 185 56 2.2
Boca Del Canon Beach
(Lost Winds) 170 31 1.3
San Clemente State Beach 107 -25 1.1
Cyprus Shore (Cottons
Point) 47 -112 -6.2
Notes: (1) Shoreline data derived from representative transect within the reach as presented in Coastal Frontiers 2025. (2) Trends derived by linear regression
(3) Data limited to end date of October 2024 because the October 2025 survey data were not yet available at the time of this report.

Figure 2-5 displays another example of this type of data with the Spring 2025 beach widths in the study area shown in context of the historical range documented at each site (comprised of all available beach profile and LiDAR data collected during the months of September through December between 1984 and 2025). The beach widths measured in Spring 2025 ranged from 16 feet at Capistrano Shores sub-reach (Transect SC-1705), to 185 feet at the Pier Bowl & T-Street sub-reach (Transect SC-1660). Spring 2025 beach widths in the Pier Bowl & T-Street sub-reach (Transects SC-1680 and SC-1660) represented historical maximums.

Farther south at the Boca Del Canon Beach sub-reach (Transect SC-1645) and the San Clemente State Beach sub-reach (Transect SC-1623), beach widths fell near the middle or upper portion of the historical range. Throughout the remainder of the region, Spring 2025 beach widths were relatively narrow by historical comparison. Beach widths were particularly narrow at the Capistrano Shores sub-reach (16 feet, Transect SC-1705), the San Clemente City Beaches subreach (25 feet, Transect SC-1695), and the Cyprus Shore sub-reach (47 feet, Transect SC-1605).

The beach nourishment projects by the USACE and by the City probably influenced these data and resulted in slight beach widening at most sites.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 28 Figure 2-5: Spring 2025 MHW Beach Widths Relative to 1984-2024 Historical Fall Beach Width Envelope
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 29 2.2. Sediment Grain Size
Sand in a given littoral cell ranges in grain size along the beach profile. Typically, coarser sand sits at the upper end of the beach profile (on the beach) and into the surf zone, while finer sand sits farther off of the beach in quieter water. The coarsest sand is in the breaker zone between 0 and -6 feet relative to mean lower low water (MLLW), where wave energy is highest, and the finest sand rests out toward the closure depth of around -30 feet MLLW. Thus, existing sand grain sizes form an “envelope” of gradations, from fine to coarse along the beach profile. This gradation envelope represents the range of grain sizes at a particular beach and serves as the basis for comparing a sand source for beach nourishment. Source sand is generally considered compatible if it falls within the existing gradation envelope or is close to its margins. An example of a grain size envelope is shown below in Figure 2-6 below.

The Shoreline Feasibility Study for San Clemente (USACE 2011) investigated nearshore grain sizes along eight different beach sections in the City. Median grain sizes ranged from

0.31 millimeter to 0.12 millimeter, with coarser sand typically found in the southern reaches of the City.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 30 Figure 2-6: Composite Sediment Grain Size Envelope for San Clemente Pier Area Example of a Grain Size Envelope
0 10
20 30
40 50
60 70
80 90
100
10 1 0.1 0.01
Grain Size, mm Percent Finer by Weight
Coarsest curve
Finest curve
Grain Size Envelope
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 31 2.3. Responses to Erosion
Recent efforts to protect vulnerable infrastructure along the Capistrano Bight have become increasingly more prevalent due to the narrowing beaches in the area. Several examples are described below.

San Clemente Beaches
The narrowing of beaches in the City present significant risks to the infrastructure along the City’s shoreline. Narrower beach widths have resulted in decreased recreational space for visitors, the loss of beachside amenities, elimination of important emergency response access routes, loss of sandy beach habitat, and increased vulnerability of the coastal infrastructure within the City to coastal hazards. Coastal infrastructure includes buildings on the beach (e.g., marine safety) or along the rear of the beach, the pier, access points, drainage outlets, and the railroad. This decrease in coastal protection may have also contributed to reactivating an ancient landslide at the south end of the City. The landslide has compromised the integrity of the coastal rail line and significantly damaged homes within the Cyprus Shore residential development.

Sand Berming: Starting in the early 2000s, the City began engaging in a biannual winter berming program. Twice per year, typically in the spring and fall, Public Works creates sand berms that protect infrastructure from wave overtopping and inundation. The amount of available native material has decreased however, and the berming can only take place along North Beach and from Linda Lane restrooms to the Boca Del Canon Restrooms. This leaves the majority of the City’s coastline unprotected.

Small-Scale Beach Nourishment: The majority of the beach nourishment efforts on record were of relatively small scale. Sand was placed on North Beach in 2005 and 2016, but the nourishment volumes were both considered small (5,000 cubic yards and 12,000 cubic yards, respectively).

Approximately 37,000 cubic yards of sand was placed at North Beach by the City in 2024 and the City is in the process of reinstating all regulatory SCOUP permits that expired. The City obtained a new 10-year SCOUP permit from the CCC in 2024, the RWQCB and USACE permits in 2025, and the permit application with the CSLC is anticipated to be issued in November 2025..

Revetment and Landslide Stabilization: Starting in 2022, the OCTA began placing additional armor stone along its existing revetment line fronting the Cyprus Shore community beach in response to accelerated coastal erosion and undermining of the railroad. The loss of beach has been especially pronounced in the vicinity of the Cyprus Shore community beach over the past five years. Presently, there is no dry sandy beach fronting the community through to the southern border of the City. The OCTA has initiated emergency work to stabilize the landslide, secure the railway tracks to the bedrock at the base of the cliff, and continues to fortify its revetment. The OCTA plans to conduct nourishment and reworking of the rock slope protection in the relatively near future but those plans are not yet completely defined or approved.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 32 Large-Scale Beach Nourishment: The City has been working with the USACE since 2002 to implement a regular beach nourishment program at a much larger scale than previous placements within the City. After the final environmental document and State Lands Commission (SLC) lease approval in August 2023, the first beach fill associated with this project began in December 2023.

Approximately 200,000 cubic yards of sandy beach material was placed via dredge and pipeline along the shore from Linda Lane to Boca Del Canon restrooms. The material was sourced from an offshore borrow site between Oceanside Harbor and the Santa Margarita River mouth. A hopper dredge was used to dredge the borrow site and transport the material to the City. Material was then pumped from the dredge into a containment basin on the upper dry beach as a slurry of water and sand. Bulldozers and front-end loaders located on the beach could then rework/spread the sand while water drained from the slurry to shape the sandy material into the designed nourishment template.

Unfortunately, the effort was brought to a halt after only approximately 114,000 cubic yards of material was placed due to poor quality of dredged sediment (City of San Clemente 2024). The material was primarily composed of cobbles, shell hash, and dark silty sediment that was not suitable for beach placement (compared to the golden sandy sized material that was expected).

Due to these complications, the borrow site was moved to an area off of Surfside Colony/Sunset Beach that has previously been used for similar beach nourishment projects with success. The remaining 86,000 cubic yards of the material was successfully dredged from this borrow site and the nourishment was completed with a total placement of 200,000 cubic yards of sand. This is the first “stage” of a 50-year nourishment project with reoccurring nourishment (stages) occurring every 6 years. The overall goal is to create a 50-foot-wide beach at a 17-foot elevation along the City beach from Linda Lane restrooms to the Boca Del Canon restrooms from every nourishment and place 2.51 million cubic yards of material over the 50-year period.

Outcome of San Clemente’s Responses to Erosion
Aside from the lack of sediment in the littoral system and along local beaches, the City shoreline does not contain physical features that act to effectively retain sand within the nearshore system.

Possible exceptions to this are the T-Street Reef and the Municipal Pier. Visual observations indicate that T-Street Reef acts to retain sand north of the feature towards the pier, and the pier appears to function somewhat like a semi-permeable groin. This results in a generally wider beach from the pier to T-Street Reef in comparison to the adjacent beaches, which are relatively narrow.

While the USACE project is the largest effort to mitigate the loss of sandy shores in the City to date, without sand retention features the beach fill material is subject to dispersing up- or downcoast and away from the City shoreline over time. The degree to which the material remains local and/or on the beach depends on the swell and weather patterns and wave energy that occur after placement, which are somewhat unpredictable (although ranges of conditions are fairly predictable over time). Beach erosion and increased sand dispersion from City shores is expected to continue without sand retention and in the face of forecasted rising sea levels and increases in storm/swell intensity associated with climate change. The present study aims to generate effective sand retention and living shoreline pilot project ideas to slow the movement of sand along the City’s coastline. The pilot projects will be designed to complement the USACE project but also function independent of it if necessary.

Capistrano and Doheny Beaches
Capistrano Beach Park has needed repeated shoring after a 2015 high tide and large southern hemisphere swell event over-washed the parking area and significantly damaged amenities and Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 33 infrastructure (Moffatt & Nichol 2019). Geotextile sandbags and sand cubes were installed as an emergency measure after the 2015 event and have since been replaced by armor stone.

More recently in late 2023, sand nourishment efforts have taken place along northern Capistrano Beach and Doheny Beach using opportunistically sourced sand from the Santa Ana River. These nourishment efforts were implemented in hopes to increase existing beach widths and to cover the cobble underlayer that has been exposed.

San Onofre State Beach
Farther south and just outside of the Capistrano Bight just south of San Mateo Point, coastal hazards were assessed for San Onofre State Park in 2019 in response to the loss of beach width and undermining of the shoreline at Surf Beach (Moffatt & Nichol 2018). In addition, high surf and heavy rain events in January 2023 resulted in the destruction and subsequent closure of the beachfront row of campsites at San Onofre State Beach within the Camp Pendleton Campgrounds that has been associated with the lack of wave buffer from the narrowing coastline (Figure 2-7).

Figure 2-7: Damaged Access Road to San Onofre State Beach from January 2023 Storms. Source:

Surfrider Foundation
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 34 2.4. Study Reaches Within the City
In order to examine conditions along the City shoreline in more detail, a series of “reaches” were identified to label subareas that possessed common traits to serve as physical units for analyses.

The City shoreline was divided into eight reaches (and two sub-reaches) for the purpose of identifying and describing existing conditions. The geographic extents of these reaches are summarized below along with a graphical representation of their locations in Figure 2-8.

1. Shorecliffs (1,250 feet) – Northern City limit (Shorecliffs Beach Club fence line) to the north end of the Capistrano Shores community.

2. Capistrano Shores (3,700 feet) – The length of the private Capistrano Shores manufactured home park community property line.

3. North Beach (1,100 feet) – Southern end of Capistrano Shores property line to the start of the continuous beachside rip-rap line along the OCTA-LOSSAN railroad (RR).

4. Mariposa Beaches (3,250 feet) – Start of OCTA-LOSSAN continuous RR rip-rap line (south of North Beach) to Linda Lane.

5. Pier Bowl & T-Street (3,700 feet) – Linda Lane to Boca Del Canon beach trail pedestrian RR crossing. This reach is subdivided into two sub-reaches:
a. Linda Lane & Pier Bowl (2,450 feet) – Linda Lane to north landing of Trafalgar Street (T-Street) Bridge.
b. T-Street (1,250 feet) – North landing of T-Street Bridge to Boca Del Canon restrooms.

6. Boca Del Canon Beach (2,200 feet) – Boca Del Canon beach trail RR crossing to Lasuens (AKA “Lost Winds”) pedestrian access trail/RR crossing.

7. San Clemente State Beach (5,000 feet) – Lasuens pedestrian access trail/RR crossing to the northern extent of the private beach fronting the Cyprus Shore residential community.

8. Cyprus Shore (4,710 feet) – The northern extent of the Cyprus Shore residential community to the Orange County/San Diego County line (just south of Cotton’s Point).

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 35 Figure 2-8: San Clemente Shoreline Reaches & City Beach Profile Locations (Surveyed by Coastal Frontiers Corporation, 2023) Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 36 2.5. Critical Erosion Hotspots
The Critical Erosion Hotspots Memorandum was published on the City website in June 2023 (Moffatt & Nichol 2023). This memorandum was largely informed by the City’s past and current Shoreline Monitoring Program that is taking place in tandem with this present Study. Results from the Fall 2022 Shoreline Monitoring Program were used in the Critical Erosion Hotspots Memorandum to determine the present-day conditions of the eight reaches of coastline within the City. Using this information as a guide, a matrix of reach “criticality” in terms of beach erosion and resource risk was created based on the last fall season survey available (Fall 2024) measured beach widths and trends. Fall surveys are compared from year to year to determine long-term changes. Each reach was also evaluated based on vulnerability of coastal infrastructure, natural resources, and recreation to shoreline erosion. The overall evaluation criteria parameters to derive ratings of “critical,” “threatened,” or “stable” for each reach are outlined in the matrix below Table 2-3.

Table 2-3: Critical Erosion Hotspots Memo Reach Parameters Criteria and Designations Matrix Parameter Critical Threatened Stable

1. October 2024 Beach
Width <100 feet 100 to 150 feet >150 feet

2. Shoreline Change
Trend (2001 to 2024) Erosion Rate >1 foot/year
Erosion Rate
<1 foot/year
Shoreline
Stability/Accretion

3. Coastal Infrastructure
Damage Risk High Medium Low

4. Natural Resource
Damage Risk High Medium Low

5. Recreational Impacts High Medium Low
A reach was classified as critical when three or more of the parameters were evaluated as critical, or if at least two of the parameters were critical and two were in the threatened category. A reach was defined as threatened if two or more of the parameters were evaluated to be in the threatened category, or if at least one was critical. A reach was classified as stable if none of the parameters were evaluated as critical and no more than one met the criteria for a threatened classification.

The matrix for the critical erosion hotspot classification criteria based on the Fall 2024 survey information is provided in the table below (Table 2-4). Based on stakeholder input, changes were made in the locations of the “back-beach” boundaries at both the Boca Del Canon and State Beaches reaches. These changes are effective from the Fall 2024 surveys. Beaches classified as threatened or critically eroded are those that could be the focus of City actions such as beach nourishment, sand retention, and living shoreline establishment. Those threatened or critical sites consist of:
• Shorecliffs,
• Capistrano Shores,
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 37 • North Beach,
• Mariposa Point,
• Linda Lane/Pier Bowl,
• T-Street, and
• Cyprus Shore.

The two sites of Linda Lane/Pier Bowl and T-Street are included in the USACE long-term nourishment project, so they may not need to be included as proposed project sites for this NBFS project. Thus, the sites that could be considered most in need for projects in this NBFS project are Shorecliffs, Capistrano Shores, North Beach, Mariposa Point, and Cyprus Shore.

The project team used this list as the preliminary candidate list for potential project sites, brought them to the community for input, and settled on Capistrano Shores and North Beach as project sites to provide benefits to the north end of town and to a popular site with multiple amenities.

Although not threatened at this time, the State Beach site was also included to provide general benefits toward the south end of town.

It should be noted that at the time of publication of this Study, the City has just collected Fall 2025 shoreline monitoring data. The data are being processed, and the City will prepare a comparison of critical hot spots in 2023 and 2025 in early 2026.

The analysis will likely show a shoreline response (widening in some areas where sand was placed in 2023, 2024 and 2025) and thus improvements along certain areas of the shoreline in response to the sand replenishment projects implemented by the City in 2024 (237,000 cubic yards added) as well as sand added by the County in 2023 and 2024 in the amount of approximately 65,000 cubic yards at Capistrano Beach via SCOUP and the OCTA sand project in September 2025 where 2,500 cubic yards of sand were added at North Beach.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 38 Table 2-4: Reach Criticality Matrix Based on Fall 2024 CFC San Clemente Shoreline Monitoring Results Location
Fall 2024
Beach Width
(feet)
Beach Width
Trend (feet/year)
Coastal
Infrastructure
Damage Risk
Natural
Resources
Damage Risk
Recreational
Impacts Rating
Shorecliffs 164 -0.25 Low High Low Threatened
Capistrano
Shores 15 -0.6 High Low High Critical
North Beach
109 (Proximity to
Public Safety
Building)
-0.8 High Medium Medium Threatened
Mariposa Point 19 -0.3 Medium High High Critical
Linda Lane and
Pier Bowl
49 (Proximity to
Public Safety
Building
+1.3 High Low Low Threatened
T-Street 153 2.2 High Low Low Threatened
Boca Del Cannon 176 1.3 Low Low Low Stable
State Beach 102 1.1 Low Low Low Stable
Cyprus Shore 18 -6.2 High Low High Critical
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 39 2.6. Opportunities
The types of opportunities that exist along the shoreline that are most advantageous for implementation include beach nourishment, sand retention and living shoreline projects are listed below. These opportunities along the shoreline enable the City to move forward on a project more expeditiously than if they did not exist.

1. Property Ownership – The City or State possesses ownership of proposed project sites along the coast;

2. Environmental Sensitivity – There is a general absence of sensitive resources such as rocky reef habitat and/or surfing resources;

3. Need – Beaches are narrow and need sand, and

4. Economics – Economic return of widening beaches would be relatively high.

A qualitative discussion of these opportunities is provided to initiate considerations for the siting of potential beach nourishment, sand retention, and living shoreline projects.

Property Ownership: The City coastline is generally defined by three owner groups: private, City, and State (California Department of Parks and Recreation or State Parks).

City – The City-owned portion of the coastline is contiguous and spans 1.9 miles from North Beach through the Boca Del Canon reach (approximately the Capistrano Shores southern property line to Lasuens Beach access). Within their own property lines and above the mean high tide line, the City would not need an ownership easement or permit from the State to place sand or install sand retention features and living shorelines along the shoreline (alongshore). The City also owns the San Clemente Municipal Pier. Other than the Pier, there are no other structures along the shoreline within the City that extend out into the water shore-perpendicular seaward of the mean high tide line. Figure 2-8 shows the reach of shoreline owned by the City, with the remainder owned privately or by the State.

State – State Parks owns 1.15 miles of shoreline within the City. The coastal portion of the City owned by State Parks exists from Lasuens beach access to the northern boundary of Cyprus Shore (State Beaches reach). State-owned beaches can add a layer of complexity to implementing a project by presenting an additional partner to consider. Conversely, planning for State Parks can also add benefits since State Parks is also a major funding partner for coastal resiliency projects in California.

Private – Private property exists along Shorecliffs, Capistrano Shores and Cyprus Shore.

Absence of Sensitive Resources/Habitat: Much of the beach and nearshore environment in the City is made up of a mix of sand and cobbles, particularly the locations of the proposed nourishment. sand retention and living shoreline projects. The beach condition of a sand and cobble mix is typically not considered as sensitive a condition as some other coastal habitats such as rocky intertidal habitat (i.e., Mariposa Beaches).

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 40 Relevant scientific literature indicates that cobble mixed with sand is less suitable habitat than sand or bedrock (SAIC 2006). Sand provides habitat for multiple species as documented by researchers (Dugan, et al. 2003) (Martin 2022). Bedrock also serves as habitat for different species than sand and is highly sensitive, as represented by low rocky intertidal habitat areas off Mariposa Point and the offshore reef (Ware 2002) (Marine Taxonomic Services 2023). However, sand mixed with cobble is more mobile than bedrock so it does not provide sufficient holdfast for vegetation, and the cobble portion can serve as an armor layer that does not host grunion, sand crabs, bean clams, etc. that are important to sandy beach ecology. Most San Clemente Beaches are relatively less environmentally sensitive than the reach along Mariposa Point and are therefore candidates to receive more sand and establish living shorelines.

Surfing: Along the City-owned portion of the coastline, sandy-bottom habitat primarily comprises the nearshore of the North Beach, Linda Lane and Pier Bowl sub-reach and the Boca Del Canon reach (Figure 2-9). As the substrate in these areas is composed of relatively mobile material (e.g., sand/cobble) and they lack sufficient sand for bar development, they are generally of inferior surfing quality compared to sites with a hard structure seabed such as T-Street Reef (e.g., rock/reef). The exception is in the immediate vicinity of the Pier where the surf quality may be higher due to some measure of longshore sand transport interruption resulting in build-up of near-shore sandbars by the pier piles.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 41 Figure 2-9: San Clemente City-Owned Shoreline Reach
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 42 The Need for Sand: Beaches in the City that are most in need of sand as noted in the Critical Erosion Hot-Spot memo summarized earlier include those classified as “critical” such as:

1. Capistrano Shores;

2. Mariposa Point, and

3. Cyprus Shore.

These reaches all present opportunities for beach building, sand retention and living shoreline activities, as do other reaches that may not be labeled as critical but are nonetheless considered threatened by coastal erosion due to lack of sand supply.

Beaches that are not critically-eroded but are classified as “threatened” are:

1. Shorecliffs – due to a sensitive environmental habitat landward of the beach;

2. North Beach – due to the proximity of the City’s public safety building, public restrooms, a playground and other infrastructure all located on a highly popular City beach with abundant public parking and is served by the OCTA rail line;

3. Linda Lane – due to the proximity of the City’s Marine Safety Headquarters, and

4. T-Street – a highly popular surf break in the City.

The remaining beach site that is considered worth widening is State Beach due to its proximity to the eroding south end of the City and benefits to public use. The City has sought to strike the right balance of sites that are in need for beach nourishment and sand retention and those that will yield significant public benefits, and that were supported by the community and decided upon Capistrano Shores, North Beach, and State Beach as Phase 1 proposed project sites.

Phase 2 project sites that have potential to host living shorelines (sand dune habitat and widened beaches) are Shorecliffs, North Beach, Boca Del Cannon, and State Beach.

The Phase 2 sites are identified as those that presently have vegetation growing along the rear portion of the beach and are anticipated to become wider as the City continues to implement both Phases 0 and 1. These sites all had and still possess remnants of living shorelines as identified from historic aerial images. They are all capable of hosting living shorelines again if widened sufficiently to prevent erosion. Additional sites can be added as the sandy beach area is widened over time. The City is of the opinion that all of these sites can experience persistent living shorelines during future sea level rise if the beaches are sufficiently wide.

Potential Economic Return of Beaches and Environmental Justice: Economic return of building beaches is typically associated with visitation patterns. Visitation patterns are strongly associated with available parking, access, amenities (e.g., restrooms, showers, food/drink concessions, volleyball nets, fire rings, etc.). Beach visitation generates revenue.

According to the beach economist that is part of the project team (Dr. Phil King, CETO, Personal Communication, 2024), the beach sites most highly ranked to generate higher economic benefits from building beaches in the City are:

1. Pier Bowl and T-Street: due to its ample parking, easy access, and attractions (Pier, restaurants, restrooms, etc.)

2. North Beach: due to the presence of a train station, parking lot, restrooms, volleyball courts, tot lot, etc.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 43 This work supported the conclusion to include North Beach as a proposed project site for further consideration.

In addition, environmental justice can be assessed through a study being conducted by the City.

The City is using experts from State universities to analyze beach attendance from environmentally burdened or underserved areas. The project will advance the current state of knowledge by developing and improving methods to estimate visitation using video analysis from Surfline Coastal Intelligence (SCI) combined with cellular device location data from Placer.ai.

Each of these methods provides distinct visitation information, with cellular device location data providing anonymized information on the home origin of visitors at the census block group level.

By overlaying available origin data with CalEnviroScreen 4.0 and identifying SB535-designated Disadvantaged Communities (DACs) at a census tract level, the project will also estimate the share of visits originating from underserved areas. These insights will support an environmental justice framework and provide a clearer picture of regional equity in coastal access. Origin data allows the team to refine estimates of the economic value of San Clemente’s beaches including estimating visitor travel costs based on travel distance to San Clemente’s beaches and the likelihood of overnight stays.

2.7. Constraints
Constraints to beach building are considerations that could make a project less effective. The constraints listed herein and analyzed qualitatively are:

1. Private ownership of proposed project site(s) along the coast;

2. The presence of sensitive resources such as rocky intertidal habitat;

3. Presence of recreational resources such as highly valued surf breaks;

4. Development along the backshore that limits space for widening beaches and installing living shorelines;

5. Beaches that are relatively wide at present and are therefore lower priorities compared to other beaches in the City, and

6. Beaches with low economic return of after widening.

A qualitative discussion of constraints is provided to assist in helping the reader to understand the ranking of sites for consideration as locations for potential sand retention/beach building projects.

Private Ownership: Private ownership of the beach to the MHTL exists along Capistrano Shores and Cyprus Shore (roughly the north and south ends of the City, respectively). Private ownership can complicate a site for consideration for beach building because there may be a lack of public access opportunities and associated economic benefits from projects and the perception that such projects would only benefit private property.

The presence of private property adjacent to the beach does not necessarily eliminate these sites from consideration, particularly if other factors that benefit the public outweigh this consideration (e.g., if a private beach connects with a public beach which is the case in San Clemente and including both areas would result in a more successful project overall). Privately owned beachfront parcels comprise 1.85 miles of shoreline.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 44 The privately owned portions of the coast exist in two separate sections at the northern and southern ends of the City. Approximately 1.15 miles of shoreline is privately owned by various entities at the northern end of the City from the border of the City and Dana Point through Capistrano Shores Manufactured Home Community (Shorecliffs through Capistrano Shores reaches). At the southern end of the City, the approximately 0.7 miles of shoreline from the Cyprus Shore residential community to the jurisdictional boundary line with San Diego County/San Onofre State Park (Cyprus Shore reach) is privately owned to the MHTL. Beyond the MHTL, the land is State owned as it is elsewhere in the City.

Presence of Sensitive Resources/Habitat: Sensitive habitat (high quality vegetated, high relief, rocky reef) exists within the nearshore zone off of Mariposa Point and at the offshore reef adjacent to that shore. Rocky intertidal habitat exists all along that location and has been identified as a constraint by the agencies for the City’s first SCOUP (Ware 2002) (Marine Taxonomic Services 2023). All other areas of the City are less environmentally sensitive with regards to shoreline habitat.

Reefs exist in ocean water deeper than is proposed for the project(s) so those sites should not be affected by beach nourishment, placement of an offshore sand retention structure or a living shoreline.

Figure 2-10 shows marine habitat areas along the City coastline. Grunion spawning has occurred at North Beach and the Pier Bowl and T Street areas, and Snowy Plover nesting occurs outside the City to the south. This can pose a constraint during construction and needs to be monitored and avoided/protected. Wheeler Reef installed by Southern California Edison in deep water off of San Clemente for mitigation purposes is shown in Figure 2-11.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 45 Figure 2-10: Biological Resources in San Clemente. Source: (Everest International Consultants 2013)
City Boundary
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 46 Surfing: Surfing is a very significant consideration for the residents of the City and visitors. The surfing heritage is deeply rooted in the local culture and history. Figure 2-12 shows the surfing locations within the City as relayed by representatives of the surfing community during stakeholder outreach meetings in 2023 and 2024. Surfing may occur at other locations that are not labeled on the figure, but those may be less frequently ridden and therefore not considered as a daily surfing opportunity. Project sites should avoid surf resources unless intentionally designed to enhance surfing. The surf quality at North Beach is considered relatively poor compared to surf resources in the southern end of the City so improvement with a project could represent a significant benefit.

Surfing locations over hard-bottom (bedrock) habitat should be considered sensitive and avoided for project placement particularly if there is high quality, high relief, vegetated rocky reef substrate that could be affected by sand burial or placement of a sand retention structure.

Reef breaks include, from north to south, 204’s (El Portal) through Mariposa Beaches, T-Street reef, and Cotton’s Point. Historically, most sandy-bottom surfing locations in the City have held ephemeral and sometimes seasonally well-shaped sandbars. However, resident expert interviews conducted in 2022-2024 indicated there is currently a lack of nearshore sand to support such nearshore bathymetry and as a result the surf quality at most of these surf spots is heavily impaired due to a lack of sand.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 47 Figure 2-11: Wheeler Reef Locations as of 2024.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 48 Figure 2-12: Surfing Sites Within the City
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 49 Development Along the Backshore: Development along the shoreline can limit the ability to implement some or all types of sand retention pilot projects and living shorelines, depending on location. The LOSSAN-OCTA railway runs just behind the back beach across the entirety of the City coastline, except along the Capistrano Shores Manufactured Home Community where it is situated landward of the community, so the presence of the community protects the rail corridor.

LOSSAN-OCTA maintains a right of way (ROW) 50 feet landward and 50 feet shoreward (100 feet total) from the centerline of its tracks and the rail line is a designated U.S. Strategic Defense Corridor. In some locations where the beach width is especially narrow, the rail line owners have installed rip-rap/revetment.

For any projects proposed to be connected to the shoreline, locations where the OCTA revetment and/or ROW extends into the intertidal zone would include coordination with OCTA as easements from this entity would be required. Specific areas of note are along the Mariposa Beaches and along Cyprus Shore reaches where the railroad is most at risk due to the lack of sandy beach.

Similar difficulties exist for on-beach projects such as living shorelines, dunes or cobble berms situated at the back of the beach that extend into the Railroad ROW. OCTA recently declared an emergency condition in San Clemente and is working to add sand to the shoreline as well as other shoreline protection (seawall or rock slope protection).

Buildings or public amenity structures on the beach may also restrict where landside pilot projects can be placed. There is a public safety building (formerly the concession stand/snack shack) and public restrooms on North Beach, a restrooms building at Linda Lane Beach, the Marine Safety Headquarters and Pier infrastructure within the Linda Lane and Pier Bowl sub-reach, a breakfast restaurant and café (West Toast Café) and restrooms building within the T-Street sub-reach, and a restrooms building at the north end of the Boca del Canon reach. In addition, the California Coastal Pedestrian Trail runs seaward of the LOSSAN-OCTA corridor from North Beach to the Boca Del Canon restroom building and a pedestrian bridge and stair set providing access to the beach is located at T-Street.

These existing structures must be accommodated and living shoreline or dune concepts should not be placed seaward of them in such a way that they adversely impact access to the ocean.

Finally, for areas where very little or no beach exists, there is no opportunity to install land-based sand retention concepts. Relevant literature (Newkirk, et al. 2018) states that a minimum of 50 feet of dry shoreline space above the Mean Higher High Water line is needed to establish a successful living shoreline project within various parts of the U.S. However, beach widths needed to host living shorelines in southern California may need to be wider at approximately 100 feet or more per work by M&N and Coastal Restoration Consultants in 2001 at Carpinteria and in 2002 at San Clemente due to higher wave energy and a large tide range. Locations that are logistically infeasible for the installation of these types of living shoreline concepts include the Capistrano Shores reach, the Mariposa Beaches reach, and the Cyprus Shore reach. Therefore, living shorelines could be proposed at existing wider reaches of beach and at sites where beaches can be widened and retained as part of this project.

Existing Wide Beaches Can Be a Lower Priority for Additional Resilience Measures:

Beaches considered wide within the City are less in need of additional sand and generally extend from the Pier Bowl south to the State Beach. North Beach is no longer in that category due to erosion. These wider beach sites would not be the first sites to be considered for a beach nourishment and sand retention project but could potentially be the sites for a proposed living shoreline. Living shorelines could be encouraged to form by simply roping off some portions of the rear of the beach where it is widest and allowing that habitat to naturally evolve over time.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 50 Potentially Limited Economic Return on Investment: A more limited economic return would potentially be realized for less accessible sites that are more distant from higher visitation areas since economic impacts are related to beach visitations/beach attendance data. There are other measures to assess economics such as damage avoidance or prevention, but the State of California typically recognizes beach attendance as the primary indicator of beach visitor/consumer spending and resulting government revenue. The less visited beaches for the City are listed below.

1. Shorecliffs – due to lack of accessibility due to flooding from the County of Orange stormwater channel that keeps the main access point closed much of the time and thus inaccessible to the public – however due to its less accessible condition it is a good site for establishing a living shoreline on the portion of the site that is already vegetated;

2. Capistrano Shores Manufactured Home Community – due to limited vertical public access at the north end and south end, though lateral access is available at some tide conditions and there is public parking available at the City’s North Beach parking lot;

3. Cyprus Shore – due to lack of parking and poor public accessibility, which is limited to the beach from either end, and lack of lateral access across the beach.

2.8. Summary of Overall Advantages and Disadvantages for Each Proposed Pilot Project
A summary of more specific advantages and opportunities and disadvantages and constraints for each of the three potential project sites are listed in Table 2-5 below as they pertain to the actual measure to be imposed.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 56 Table 2-5: Summary of Advantages and Disadvantages for Each Potential Project Site Alternative Advantages Disadvantages
North Beach • Creates habitat from living
shoreline to subtidal (room along
the rear for dunes)
• Builds a beach
• Protects the backshore
• Surfing improvement
• Adaptable to sea level rise
• Relatively larger economic benefits
• Good public access
• Partnering opportunity with both
Capistrano Shores and the OCTA
• High relative costs
• Possible navigation safety
hazard (emergent/visible
breakwater)
Capistrano Shores • Creates sandy beach and subtidal
habitat
• Builds a beach
• Protects the backshore
• Adaptable to sea level rise
• Lower relative costs
• Connects lateral access
alongshore
• Partnering opportunity with the City
• Private property
• Lower relative economic benefits
• No surfing improvement
• Definite navigation safety hazard
(submerged/less visible
breakwater)
• Restricted public access
State Beach • Creates more sandy beach and
subtidal habitat
• Builds a beach
• Protects the backshore
• Possible expansion of living
shorelines
• Surfing improvement
• Connects lateral access
alongshore Partnering opportunity
with State Parks, and the OCTA
• High relative costs
• Public property and private
property
• Possible navigation safety
hazard
• Restricted public access
• Could reduce sand transport to
south and keep sand within the
City longer
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 57 3. Conceptual Alternatives Development Process
The City intends to implement NBS to address coastal erosion problems. The NBS approach and the process for identifying suitable projects is described below.

3.1. Additional Background for NBS Alternatives
The CCC encourages the integration of NBS into coastal planning and management strategies to ensure that they are effective and sustainable. This study is funded by an LCP Planning Grant awarded to the City from the CCC, and they identify a range of NBS in a Nature-Based Adaptation Strategies memorandum (California Coastal Commission 2021), including:
• Coastal Ecosystem Restoration: Restoring or enhancing natural coastal habitats like mangroves, salt marshes, and beaches to provide natural buffers against erosion and storm surges.
• Green Infrastructure: Implementing green infrastructure in coastal cities to provide natural coastal protection.
• Dune and Beach Management: Managing dunes and beaches to maintain their natural functions and protect coastal areas.
• Habitat Enhancement: Enhancing or restoring habitats for marine and coastal species.

The CCC recognizes that NBS offer multiple benefits, including:
• Increased Coastal Resilience: Enhancing the ability of coastal areas to withstand climate impacts.
• Biodiversity Protection: Protecting and restoring natural ecosystems and their biodiversity. • Improved Human Well-being: Providing recreational opportunities, improving water quality, and enhancing the aesthetic value of coastal areas.

The City of San Clemente seeks to complete their path toward advancing long-term coastal resilience with a range of projects addressed herein. City visions of nature-based solutions include replicating natural features such as dunes, beaches, reefs, headlands and other natural features that occur in nature and are either shore parallel and/or shore perpendicular.

The City’s Goal is to: design with nature, looking at natural sand retention features, such as headlands, peninsulas, finger reefs and similar natural structures and to attempt replicating them with man-made techniques and approaches.

3.2. The Process of Identifying NBS Alternatives
In response to widespread coastal erosion throughout San Clemente’s shoreline, the City has begun implementing a comprehensive shoreline management strategy involving:

1. Preparing a sea level rise vulnerability assessment in 2019,

2. Preparing a Coastal Resiliency Plan in 2021,

3. Conducting regional shoreline monitoring (restarted in 2022),

4. Planning and implementing opportunistic sand replenishment projects under SCOUP,

5. Implementing a 50-year beach sand project in collaboration with the USACE, Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 58 6. Participating in the SANDAG RBSP III,

7. Working with OCTA to ensure timely placement of sand along the City shoreline, and

8. Conducting this Study to evaluate the potential feasibility of optimizing the performance and economics of an NBS project for adaptation as a companion strategy to long-term beach sand replenishment projects.

NBS features are being conceptually designed to replicate local, naturally occurring features such as beaches, dunes, reefs and headlands that occur in the City and region. Such natural features occur parallel, perpendicular, detached, and/or attached to the shoreline.

The objective of the conceptual alternatives development process was to identify opportunities to design with nature, as a companion strategy to beach and dune building/nourishment, to increase the sand supply within the City resulting in increased beach widths over time. NBS including beach nourishment could potentially be coupled with sand retention using headlands, peninsulas, finger reefs and similar natural (i.e., nature-based) structures and living shorelines to reduce wave energy and erosion at the beach and hold sand in place longer than would occur without retention.

There are several existing natural features adjacent to the City’s shorelines that have been used as inspiration to develop conceptual NBS alternatives of beach and dune building with sand retention. These naturally occurring features can be replicated to stabilize the shoreline in vulnerable areas without jeopardizing the natural processes.

In this Study, beach building through nourishment is referred to as Phase 0 since this phase is already underway at the City. Sand retention with nourishment is referred to as Phase 1. Phase 1 would be implemented as the next phase after initial nourishment and monitoring informs City decision-making. Phase 2 is implementation of other natural stabilization approaches such as living shorelines at the rear of the beach which could occur along existing wide beach reaches within the City (e.g., Boca Del Cannon and State Beach), and at other beaches after they demonstrably widen (e.g., North Beach and Shorecliffs) sufficiently to buffer and feed the dunes while accommodating needed recreation and shoreline protection needs. As stated previously, beach widths needed to host living shorelines are approximately 100 feet or more per Coastal Restoration Consultants in 2023, while Newkirk, et al. 2018 indicated they need to possess 50 feet of dry shoreline space above the Mean Higher High Water line.

In order to develop conceptual alternatives for Phases 1 and 2 of the project, a range of possible alternatives was developed for each shoreline reach and is presented herein. Designs were categorized by project type and spatial scale to build a matrix of possible options from which to choose. For each reach the broader list was then refined based on the physical and economic needs/constraints of that specific location. Eventually, these alternatives were refined into a set of initial concepts presented to the City and public for review in 2023 and 2024. The final set of initial concepts and public review process is discussed below.

3.2.1. Screening Alternatives
The first step of the conceptual alternative development process was to establish a list of all possible coastal resiliency infrastructure and project types for a particular location. Alternatives were developed around three different project types: 1) beach nourishment, 2) sand retention, and 3) living shorelines. For each project type, ideas were separated into different spatial scales and magnitudes of change. Smaller scale ideas that do not require a large magnitude of change were defined as “light touch.” Large scale ideas that require a high magnitude of change were defined as “larger project” and those that fell in between these two scales were defined as Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 59 “medium-scale.” All concepts that were developed were then binned into these categories for further screening.

The City has identified conceptual design criteria for each alternative. Design components are to include:

1. Community resilience benefits – increased protection to coastal infrastructure.

2. Recreational preservation or enhancements – (e.g., recreation (e.g., sunbathing, surf fishing, volleyball, walking, surfing).

3. Ecological benefits – increased sandy beach ecology, living shorelines, rocky intertidal habitat and subtidal hardbottom habitat.

4. Proof of concept – demonstrated success at widening beaches, improving surf, and increasing habitat areas and diversity.

5. Transferability/scalability beyond the funded project – able to be applied to other southern California locations that possess similar conditions to San Clemente.

A list of specific project performance criteria was also used to inspire the ideation process and create a comprehensive list of conceptual alternatives to choose from. Project performance goals included the following:

1. Protect infrastructure – reduce damages and needed future repairs caused from coastal storm wave events, sea level rise, and climate change.

2. Improve public safety and coastal access – provide additional access routes along the shore that may not presently exist (e.g., around Mariposa Point as occurred in the past) and to enable marine safety staff to drive along the beach under emergencies to reach incidents without having to drive through the City.

3. Increase and improve existing recreation opportunities – provide more and better opportunities for walking, sunbathing, volleyball games, fishing, surfing, and swimming conditions.

4. Protect the environment and facilitate ecological function of coastal habitats – add sandy beach habitat area at each project site, along with hard-bottom habitat in subtidal, intertidal, and supratidal conditions for colonization of living shorelines and kelp, algae, possibly surfgrass, and other marine habitat types.

5. Create a natural buffer by establishing and maintaining a wide sandy beach – add to the protective function of a beach for coastal infrastructure along the majority of the City by increase the beach width, elevation, and length so that the City and others can rely less on rock revetment and more on soft materials.

6. Enhance the USACE Project performance through retention of placed sand – create conditions that result in sand placed by others, specifically the USACE and potentially the OCTA, to remain within the City longer than would otherwise occur by installing features to slow alongshore ocean currents and longshore sediment transport rates.

With these project performance criteria in mind, a matrix of possible alternatives was developed to use when selecting and refining possible concepts for each shoreline reach. This matrix is presented below.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 60 3.2.2. Range of Possible Options (Book Ends)
Table 3-1 presents the matrix of possible design alternatives used for screening alternatives. The City’s shoreline was assessed for opportunities and constraints to understand which project types and scales would be most feasible. Specific needs of each location were considered, and a list of potential alternatives was developed. Options for large scale beach nourishment (millions of cubic yards of sand) were considered but rejected due to potential environmental impacts.

An extensive list of alternatives for each shoreline reach was developed and then screened (i.e., retained or rejected) based on feedback from the project team and City. All alternatives used for screening are shown in Appendix D of this report. These concepts were refined into three initial alternatives that are presented in Section 3.3.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 61 Table 3-1: Matrix of Possible Design Alternatives Used for the Screening Process Magnitude of Proposed
Change
Project Types
Beach Nourishment Sand Retention Living Shoreline
Light Touch Strategic small-scale nourishment
(less than 100,000 cy of sand) in
most vulnerable reaches
Small supplement to USACE
nourishment project (piggybacking)
Small re-nourishment in
coordination with USACE project
SCOUP Program Re-Establishment
Participate in the OC Parks
Regional Strategic Plan
Be added to SANDAG RSBP III
Cobble toe/berm fortification with
native or similar cobble-sized
material
Restack rip-rap in a way that
maximizes beach towel space and
erosion prevention
Long, linear dune like Cardiff where
the beach is sufficiently wide and/or
vegetation already exists (rope off
and install shims)
Optimize sand berming practice by
making seasonal sand berms into
permanent dunes is possible
Add cobble to the dune toe for
added resistance to erosion
Medium-Scale
Includes all “Light Touch”
strategies in addition to those
indicated in respective
categories
Larger-scale nourishment over
longer reaches (more than 100,000
cy of sand)
Larger supplement of USACE
nourishment project (piggy-back)
Larger-scale re-nourishment in
coordination with USACE project
Permeable Pile Pier Structure (e.g.,
of concrete rather than wood or
regular concrete) attached to the
existing pier and added to the south
Nourishment with a small pilot sand
retention project such as the
following:
• Groin (e.g., alongside Pier)
• Miniature artificial cobble delta
wave refraction structure
connected to shore (Trestles
replica)
• Miniature living nearshore reef
connected to shore (T-Street
replica)
Engineer longer, linear dune like
Cardiff to promote colonization
(remove non-natives, seed, rope off,
install shims), restack rip-rap and
build dune on top
Build dune field if wider beaches
form (install shims and rope off)
Dunes as learning lab to compare
different dune types/designs for
performance
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 62 Magnitude of Proposed
Change
Project Types
Beach Nourishment Sand Retention Living Shoreline
Larger Project
Includes all “Light Touch” &
“Medium-Scale” strategies in
addition to those indicated in
respective categories
Feeder Beach – Large Scale (e.g.,
more than 1,000,000 cubic yards) –
Regional in nature rather than local
Sand Engine – Huge Scale (e.g., 7
million cubic yards), 250 feet wide
beach, continued renourishment
Very large supplement of USACE
nourishment project (piggybacking)
Very large-scale re-nourishment in
coordination with USACE project
Perched Beaches – Held in position
by a retaining wall along the
seaward side of the beach
Nourishment with a large pilot sand
retention project such as the
following:
• Offshore Breakwater(s)
• Groin Field
• Artificial headland
• Full-sized artificial cobble delta
wave refraction structure
(Trestles replica)
• Full-sized living nearshore reef
connected to shore (T-Street
replica)
• Series of nearshore
reefs/T-Street replicas/Trestles
replicas
• Extension of existing natural
features to increase sand
collection (Mariposa Point,
Cottons Point, T-Street reef, Seal
Rock)
• “Speed bumps” per the
Oceanside Re:Beach project that
are small headlands extending
from shore to interrupt longshore
sand transport and build
beaches
Turn entire back-beach into a
continuous dune field with multiple
ridges
Convert riprap into ECOncrete
material for marine growth increase
Convert intertidal
revetment/bulkheads into “tide pool”
revetments to expand and promote
intertidal habitat
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 63 3.3. Vetting the Initial City Concepts with the Public Throughout the course of the project, a public outreach and feedback program has accompanied the development of concept design alternatives. This was done in both public meetings and with focused stakeholder groups/forums to garner general reception of concepts, generate feedback for refinements based on community and stakeholder requests, and integrate outside ideas into the designs.

Presentations and/or meetings at San Clemente City Hall were held throughout the process to garner as much community engagement into the project as possible. Focused stakeholder group meetings generally incorporated an open-discussion presentation with concept designs presented in virtual and large-print format for markup by the group.

A set of initial concepts were presented to the City and the public for review and comment at various public meetings held in September 2023, February 2024 and July 2024. The initial design concepts developed by the team were presented to the public on September 27, 2023, and were made available for public review on the City website from September 29, 2023, through November 17, 2023. A total of ten initial design concepts were presented at this initial public meeting to solicit feedback and input that could be used to refine the concepts.

Based on stakeholder feedback, the initial (Round 1) design concepts evolved into Round Two designs with five (5) Phase 1 designs and five (5) Phase 2 designs which were presented on February 29, 2024. These designs were made available for public review and comment from February 15, 2024, through April 29, 2024.

Based on stakeholder feedback, the Round Two designs evolved into the Round Three designs which were presented to the public, via the Coastal Advisory Committee on July 18, 2024. The design concepts were available for public review and comment through September 6, 2024.

As previously mentioned herein, the team also met with other identified stakeholder groups and representatives including the OCTA, Surfrider Foundation, Bring Back Our Beaches community group, Save Our Beaches community group, the North Beach Community Association, and the Capistrano Shores Homeowners Association. Sessions of focused stakeholder meetings were conducted in July-August 2023 and in June 2024, to obtain feedback for refinements prior to the September 2023 and July 2024 public meetings.

Key takeaways from the feedback received to date are listed below:
• There is a wide diversity of opinions and perspectives; • There is a general lack of support for experimental or otherwise unproven techniques/strategies;
• There is strong support for proven techniques used elsewhere in the region, State and beyond, so long as they are within similar oceanographic environments to San Clemente; • There is strong support for a City-wide program with options for all beaches, especially North Beach and beaches toward the southern end of the City; • There is strong support for large-scale, sustained City-wide beach nourishment; • There is strong support for sand retention features if deemed required after sufficient nourishment has taken place and monitoring concludes that retention is necessary; Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 64 • There is greater support for shore-parallel (e.g., reefs, breakwaters, etc.) retention structures rather than shore-perpendicular retention structures, however, feedback was mixed showing support for both types of structures;
• There is moderate support for living shorelines and dunes provided they do not result in a loss of towel space for the public;
• There is a lack of support for the cobble delta concept; and • There is a need to monitor the City of Oceanside Re:Beach project and learn from their process and deliverables.

In the end, the team recommended the City consider beach nourishment with shore parallel sand retention features combined with living shorelines. Breakwaters are designed account for the bi-directional longshore sediment transport condition in the northern Oceanside Littoral Cell and specifically in San Clemente due to its exposure to southern swell, and to address the public preference for offshore and shore parallel treatments.

3.4. Revised Draft Sand Retention Concepts – Phase 1 (Near Term) Descriptions of the revised draft concepts are provided below in order of most likely to be implemented (North Beach) versus least likely to move forward (State Beach), assuming that the City prioritizes actions at a public beach that they own. The descriptions include a general discussion that is supplemented by specific details of each concept.

3.4.1. Concept 1 – North Beach Multi-Benefit Emergent Breakwater

3.4.1.1. General Overview
This Phase 1 concept is an emergent rocky reef, shore parallel breakwater situated between the north end of the North Beach Reach and the south end of the Capistrano Shores Manufactured Home community (Capistrano Shores community) reach shown in Figure 3-1. It would be constructed of armor stone material and have a “barbell” shape design and would be located approximately 900 feet offshore and in water depth of 15 feet.

The submerged, flared sides of the structure would gently slope down around the seaward and side edges to enhance surfing opportunities, and the central/main segment would have steeper slopes on both the shoreward and seaward sides of the structure to dissipate wave energy. The crest along the top of the reef/breakwater would be emergent at all times at an approximate design crest height of +10 feet relative to North American Vertical Datum 1988 (NAVD88). The preliminary design concept would be confirmed or possibly modified by further engineering in the next phase of the study. The City is applying for State funding to take this concept to the next stage of engineering. Specific tasks to be conducted include additional design (to 60 percent), environmental and permitting tasks). Two other project concepts are being considered elsewhere (Oceanside for Re:Beach by the City of Oceanside and at Pacifica by a citizens group) and the City is keeping abreast of developments and changes that could potentially bear on the design of this concept.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 65 The structure would be positioned parallel to the shoreline and just offshore of the coast. It would be designed to form a salient, or a bulge in the beach in its lee, caused by slowing of longshore sediment transport and reduction of incident wave energy. It would create both recreational and habitat opportunities and locally protect the North Beach and Capistrano Shores areas. These beaches have experienced significant beach erosion and undermining that has threatened shoreside infrastructure. Unique amenities exist at North Beach, and the design concept could supplement them to increase potential benefits of revitalizing and protecting this reach of the shoreline. This concept was adapted from the City of Oceanside Sand Replenishment and Sand Retention Project (GHD 2021) which preceded and stimulated the Re:Beach effort.

The Phase 2 portion of this project would be forming dunes along the base of the berm that supports the railroad. Although not shown on the graphic for the Phase 1 concept, the dunes would be a linear feature at the landward edge of the beach just south of the restroom building where vegetation presently exists.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 66 Figure 3-1: Conceptual Schematic for North Beach Multi-Benefit Emergent Breakwater Phase 1 Project Concept

1. Multi-benefit emergent surfable breakwater

2. Pre-filled sand nourishment and eventual shoreline
1 2
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 67 3.4.1.2. Site-Specific Opportunities
Locating this structure offshore at North Beach has the potential to provide significant additional recreational and socioeconomic benefits to the City. There are 15 public access points in the City and North Beach has one of only four of the 15 City-owned shoreline beach access points that also provides adjacent public parking facilities. The other access points that also provide parking spots are at Linda Lane, the Municipal Pier, and at T-Street. The City’s primary OCTA/Metrolink train stop is located at North Beach, offering public transit options for visitors. The secondary train stop is located at the City’s Municipal Pier.

The beach at North Beach is currently heavily undermined and actively eroding according to the ongoing shoreline monitoring program results (Coastal Frontiers Corporation 2024). The current beach is composed of both sand and cobble, making it a less desirable location for users compared to other beaches. The existing public safety building and public restrooms on the beach are compromised due to undermining and currently closed as a result. In Spring 2025, the City was forced to remove portions of the building’s perimeter decking and fence which were damaged during a storm wave event.

The City is currently revitalizing North Beach and the surrounding Los Molinos District to bring more tourism, commercial businesses, hotels, restaurants, and other attractions to this historic district. Concurrently improving the beach and installing the proposed offshore structure would help protect and enhance the shoreline, promote recreation, and protect infrastructure from coastal hazards while also improving habitat. A pilot project installed in this location would serve to supplement both the community enhancement and coastal resiliency efforts underway by the City.

Fronting the Capistrano Shores community, there is effectively no dry sand beach above the mean high tide line and the homes within this beachfront community are under increasing threat from coastal erosion and flooding. Establishing a sand retention feature and prefilling the beach could greatly benefit this part of the City by offering protection from erosion with a wider sandy beach. Widening this portion of the beach would be a public benefit due to proximity to available public parking and access and would also restore lateral local and regional coastal access from the south end of the City into Dana Point providing benefit to upcoast beaches in Dana Point and the County/State Parks.

3.4.1.3. Preliminary Design Elements: Dimensions, Position and Pre-Fill Volume The current design is at a 15 percent level. Additional engineering and design, as well as numerical and physical modeling will be required in the next phase to refine the designs to ensure optimal performance. Table 3-2 shows the properties of the concept.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 68 Table 3-2: Summary of North Beach Concept Characteristics Concept Function Position/Depth Planform Dimensions Crest Height Sand Quantity
New Beach
Area Created
North Beach MultiBenefit Emergent
Breakwater
Block wave
energy; create
surfing site
and a beach;
establish
intertidal and
subtidal hardbottom habitat;
eventually
establish a
living shoreline
in Phase 2
Shallow
nearshore -15
feet; located
900 feet
offshore
Linear crest
with rounded
ends (barbell)
1,300 feet
long; 350 feet
wide; 700 feet
widened and
rounded ends
+10 feet
NAVD or
emergent at all
times, with
sloping
shoulders
500,000 to
600,000 cubic
yards
8-13 acres
The shore-parallel, hybrid breakwater/reef would be located offshore at North Beach. The footprint of the “barbell” shaped structure would be approximately 1,300 feet long, 350 feet wide in the center along the midpoint, and 700 feet wide at the ends. It would be situated approximately 900 feet offshore to form a salient, or a bulge in the beach planform as a wide point with tapering shoulders.

The salient would be created in the lee of the structure by (a) slowing of longshore sediment transport and (b) reducing wave energy.

At this location, the structure is in a depth of water between 10-20 feet.

A crest approximately 1,000 feet long and 130 feet wide would be emergent (i.e., visible) at all times. The crest planform would be angled (“doglegged”) at about 45 degrees towards shore for the last 200 feet of each end. The emergent crest would be constructed to an elevation of +10 feet NAVD88. This implies that under current sea level conditions, at the lowest spring tides about 11-12 feet of the breakwater crest would be exposed and at the highest spring tides approximately 2-3 feet of the breakwater crest would be exposed.

The rationale and benefit for having the structure emergent/visible is to ensure it reduces the energy of the biggest storm/winter waves and to ensure that these extreme events to do overtop the structure so as to disrupt and dissipate the wave energy so that it does not cause erosion of the beach. In addition, having a structure that is visible at all times will also have a secondary benefit of not creating a hazard to mariners. Local examples of offshore rocky structures in the City that are emergent occur at Wash Rock in the north end and Seal Rock/San Mateo Rocks at the south end of the City.

A prefill volume of sand would be placed on the beach during construction equivalent to the volume of sand that could be retained by the structure. This prefill is shown as item number “2” in Figure 3-1. The intent and goal of pre-filling the beach with sand is to mimic the anticipated salient that would eventually form leeward of the structure. Sand pre-filling of the salient is done to prevent littoral drift from accumulating in the deposit causing deprivation to the downcoast beach.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 69 The prefill would be new sand added to the littoral cell and would be shaped to form a beach that is approximately 430 feet wide at its widest point directly in the lee of or eastward of the breakwater, eventually tapering down to meet the existing pre-project shoreline position moving farther away from its protective beneficial sand retention shadow. This would likely encompass an area that is between approximately 350,000 and 575,000 square feet in size (8 to 13 acres [ac]), thus requiring between 500,000 to 600,000 cubic yards of sandy material as pre-fill.

Consideration of an overfill factor such as 10 percent to 15 percent is standard coastal engineering practice and is assumed in all beach sand replenishment projects.

3.4.1.4. Planning, Engineering, and Design Phases
The project will need to be planned (environmental review) engineered for construction and permitted prior to implementation. These phases consist of preliminary engineering to conduct environmental review under the California Environmental Quality Act (CEQA) and the National Environmental Policy Act (NEPA) and permitting. After CEQA/NEPA and permitting are completed, the final engineering can occur for construction. Engineering will probably include numerical modeling of the performance of the project for design refinements, and then physical modeling of it in a laboratory to prove the concept. All of this information will be incorporated into the final engineering documents for construction.

3.4.1.5. Construction and Performance Monitoring
The hybrid breakwater/reef is proposed to be constructed out of armor stone, with the specific sizes to be determined more precisely by future engineering and modeling (numerical and physical) efforts. The exact size of stone required would be developed during the pre-construction and design engineering phase which would follow the current Feasibility Study phase.

After construction, monitoring would be required to quantify the performance of the project.

Actions will include physical monitoring of the shoreline, waves, and the structure, and biological monitoring of habitat at the site and in the nearby coastal reach. Logistics of monitoring are addressed below.

Logistics of Monitoring
Shoreline monitoring includes measuring beach profiles and recording ortho-rectified aerial images for the beach to a position up-and downcoast where no shoreline effects are discernible.

This project specifically proposes to add sand to the littoral cell to compensate for the sand-retaining function of the breakwater. The quantity of sand proposed is more than the volume to be retained so that the entire North Beach can be nourished and sand can also be contributed to the adjacent shoreline areas both up- and downcoast. Monitoring will extend north and south an appropriate distance to capture adjacent effects, and potential adaptive management actions could include nourishing neighboring beaches to compensate for any project-related impacts.

Wave monitoring can be done using camara images from a stationary position over time using Surfline AI for analyses combined with surveys of local surfers.

Biological monitoring would need to be done in the field with surveys of the beach and backshore for habitat, and a combination of drone images and SCUBA diving for the ecological conditions of the breakwater.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 70 Results of the monitoring would be used to determine if the project performed as intended (to retain a beach without causing long-term environmental impacts) or needs to be modified to improve/optimize its performance using adaptive management protocols. For example, the breakwater could be lengthened and/or raised to provide continued protection under rising seas.

Biological monitoring would clarify whether plant and animal species have colonized the structure and whether additional ECOncrete units need to be added to the breakwater to increase colonization. Also, beach ecology could be evaluated to determine how the added beach affected sand dwelling organisms and species that feed on them. Also, surfing monitoring could document changes to surfing conditions at this location. If surfing is not possible or considered of moderate quality, then either the slopes of the breakwater ends could be modified to create a higher quality surfing experience.

Conversely, if the post-construction monitoring were to show that there are negative effects to the adjacent shoreline or safety concerns as a result of its construction then the structure could be modified using adaptive management protocols such as removal or being scattered over the seabed. It could be dismantled and/or spread out along the nearshore seabed to provide new hard-bottom subtidal habitat or be fully removed from the site using marine construction equipment.

3.4.1.6. Shoreline Enhancement Benefits
This project would widen North Beach over a distance of 2,580 feet to a maximum of 430 feet behind the breakwater. This sand beach would provide added protection to the backshore, recreational play area of up to a maximum of approximately 13 acres, and new sandy beach habitat where it does not presently exist. The beach should be stable and persist over near all conditions throughout the typical year and into the 50 to 75 year future including sea level rise, thus providing a dependable resource for the City to enjoy. Protection of the building, railroad, and parking lot is a major benefit from the widened beach. The definition of success for shoreline protection is that:
• the beach reaches 250 feet wide at its apex (widest point), • narrows but continues to exist during severe coastal storm conditions (e.g., 5- to 10-year wave event) to protect the backshore, and
• recovers after storms back to a 250-foot width.

Sea Level Rise
Sea level rise will affect all features along the coast including San Clemente’s project sites. At North Beach, as sea level rises the beach will gradually retreat with the rate of rise. According to the Bruun Rule (Bruun 1954) (Bruun 1962), if climate change affects only the sea level, while leaving the wave climate unchanged, Bruun reasoned that the slope of the equilibrium shoreface profile then should also remain the same. The profile should move landward and upward, however, to keep the same position with respect to sea level as before. However, this theory assumes that sand is available landward of the beach to nourish the beach as water rises, which may or may not be case throughout San Clemente. Hard backstop exists throughout much of the City, including at North Beach.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 71 Therefore, if there is no sand supply from landward sources, sea level rise will lead to a gradual ongoing submergence of the subaerial beach, starting with beach lowering adjacent to the sea wall or hard backstop (Beuzen, et al. 2018). To counteract this process, the breakwater will act to artificially keep the beach wide enough to delay its recession landward toward the hard backstop.

However, renourishment will be required eventually to completely offset the landward recession of this beach during sea level rise. Theoretically, with sufficient renourishment and the wave shadowing benefits of the breakwater, this beach should be able to exist for the long-term future of 75 years or more.

The living shoreline can also persist into the future if the beach is maintained in a relatively wide condition. Typically, the beach width needed to sustain dunes is between approximately 50 and 100 feet. This can be achieved at this site with the adaptation to the breakwater plus periodic renourishment as sea levels rise.

The Public Trust Boundary
The boundary between the State and the City and private properties along beaches is the MHTL.

It is the legal boundary referred to as the public trust boundary. This is the line on the shoreline that the water reaches during a mean high water event. That line is equivalent to an approximate elevation of 4.75 feet above mean lower low water, or the 0.0 value on a tide chart or in a tide book. The MHTL is a line that shifts with changes to the position of the shoreline, meaning that beach nourishment and sand retention can cause the boundary to shift farther away from shore if beaches become wider.

The State of California owns land seaward (to the west) of the MHTL toward the ocean, while the City owns the beach landward (to the east) of the MHTL at North Beach. As such, the effects of beach nourishment and sand retention typically result in the MHTL shifting seaward which would cause the City to own more of the beach. Typically, the State requires a MHTL survey prior to the nourishment project as part of permitting so that the boundary can be set and remain unchanged in the future after nourishment, so the line will likely not change in landownership documents but may show a shift on the ground.

This alternative would shift the MHTL shoreline seaward to occupy approximately the seaward boundary of the eventual shoreline shown in Figure 3-1 for this alternative.

3.4.1.7. Recreation and Access Benefits
The hybrid reef/breakwater is designed with a barbell-style planform shape and sloping submerged edges to focus and refract incoming wave energy in a way that creates conditions for surfing. It is conceptually designed to create waves breaking in two directions (to the left and to the right) on the north and south side of the structure, respectively. For non-surfers, the salient and sand accumulation leeward of the reef/breakwater would provide a protected wading and swimming area.

By placing the structure at the northern end of North Beach, the adjacent 204’s surf break would not be affected. The prefill and sand accumulation of the project would be a sufficient distance from the 204’s surf break to not result in any long-term or permanent changes in nearshore bathymetry. Since the surf at North Beach is generally lower quality, the project should improve surfing opportunities at North Beach and south Capistrano Shores.

Other forms of recreation will be improved with a wider beach as well. The beach will provide area for walking, sunbathing, swimming, volleyball, sightseeing, and collecting. The quiet water zone Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 72 behind the breakwater may provide an opportunity for SCUBA diving in that it provides a safe entry/exit to and from the water on most days. A relatively short swim by a diver could enable them to reach the reef and dive around its perimeter to view sea life along the structure.

Annual beach visitation will very likely increase in numbers because it is typically constrained by towel space on the beach and the project will significantly increase that component. Also, ample parking and public transit exist at this site, making it is very accessible to visitors both local and distant.

3.4.1.8. Ecological Benefits
The ecology of the project includes sandy beach habitat, subtidal marine habitat, and remnant sand dune habitat. Each habitat type is addressed below.

Sandy Beach Habitat
The project site was evaluated in detail by Coastal Resources Management (CRM) in 2000 for the City’s Opportunistic Beach Fill Program (early version of a SCOUP).

In the CRM report (2000), the actual beach area of the North Beach site is described as:
“…composed of medium to coarse sand with no rocky intertidal habitat along this part of the shoreline. Typical sandy beach organisms (worms, sand crabs, amphipods, isopods, and clams) exist between the low and high tide marks and will vary on a seasonal basis as a result of changes in physical beach characteristics. All of these species are resilient and have life histories based upon high seasonal turnover.”
This assessment led to the site being deemed suitable for beach nourishment because it would not cause a permanent adverse impact to the beach ecology, so the site was identified as a sand receiver site for several sand placements in 2005, 2016, and 2024.

In addition, beach nourishment would definitely serve to increase the area of sandy beach habitat at this location and create the potential for nature-based solutions along the rear of the beach. A Shoreline Characterization Study was conducted City-wide by Coastal Restoration Consultants for this project (CRC 2023). They identified the North Beach site as having significant potential to host nature based solutions due to its existing width and the added fact that vegetation already exists along its landward portion. As stated in their study, “There was strong spatial correspondence between areas currently supporting beach vegetation and the potential for using nature-based solutions based on California’s natural infrastructure guidance. Vegetation observed in the survey was found only on wide beaches that generally met the criteria set by the California natural infrastructure document, reinforcing the guidance on siting nature-based projects within sufficiently wide beaches for climate adaptation.” Subtidal Hard Bottom Habitat
In the area where the reef/breakwater is proposed in the nearshore, CRM 2000 describes the habitat as:
“…the seafloor is sand to depths of approximately -7.5 feet MLLW, about 500 feet from the engineering basepoint at the railroad tracks. The sandy seafloor transitions to sand and patchy, low relief boulders at this distance. The reefs are partially covered with sand. Individual rocks with greater relief support growths of filamentous red algae, crustose corallines, coralline algae, and surfgrass. Surfgrass is present a minimum of two feet off of the ambient sand level seafloor Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 73 (-7.5 feet MLLW). Generally, the rocks and the surfgrass rhizome mass are covered with about 2 inches of sand, and the surfgrass blades are 2 to 3 feet long.” As the reef is proposed to be positioned in a water depth of -15 feet NAVD (nearly equivalent to MLLW), the reef would in deeper water than the surfgrass area and therefore avoid this subtidal habitat and potentially lead to an extension/expansion of it. Review of existing available bathymetric survey data and visual assessment of aerial photography indicate that the majority of the seafloor is low relief seabed composed of sandy bottom or low relief, highly scoured reef (as noted by CRM above). Data suggests the site is largely absent of higher relief, high quality reef habitat that could be affected by an offshore structure. In the next project phase, pre-construction habitat surveys would be completed to verify and document the sea bottom conditions to confirm any presence of vegetated rocky reef.

Remnant Sand Dune Habitat
The North Beach site was observed to have vegetation growing along the back of the beach by CRC in February of 2023. Unfortunately, the vegetation growing on the rear of North Beach was iceplant and Myoporum. However, according to CRC “the presence of living plants indicates appropriate growing conditions for native dune plants and areas with infrequent wave disturbance.” Therefore, this project will include an initial dune along the rear of the beach to represent a living shoreline. If physical conditions serve to create and maintain dunes in Phase 1 then the City will pursue that direction. At a minimum, the City will conduct dune building as part of Phase 2, but if dunes can form in Phase 1 then they may be able to be expanded in Phase 2.

Future Possibilities
The definition of success for ecology is that:
• the beach possesses the entire range of sub-habitats (upper intertidal, mid-intertidal, and low intertidal) through-out the year across its widest point • the breakwater serves as an attraction for marine organism colonization with the typical local species of mussels, gorgonians, keyhole limpets, urchins, sea cucumbers, Kellet's whelk, sea stars, spotted sand bass, kelp bass, senorita, bat rays, and black perch.

Establishing a wider beach provides an opportunity for shorebirds, native vegetation, and intertidal infaunal and fish species that inhabit sandy beaches to utilize the space as an expanded local habitat. It may also provide an opportunity for sensitive species (such as grunion), threatened or endangered species such as least terns and snowy plovers and back beach dune vegetation to expand within their regional distribution range setting the stage for potentially implementing a living shoreline once the beach has sufficiently widened over time.

The project would be designed to attract marine growth on the hard-bottom material (stone). The proposed reef is proposed to be constructed out of armor rock, situating it in an ecologically less sensitive area of the seafloor to enhance the habitat potential for subtidal and intertidal species colonization and use. The process is intended to function somewhat similar to the SONGS Wheeler Reef mitigation project reef modules located farther offshore in deeper water off of this site. The breakwater structure could also potentially be enhanced to maximize habitat potential, biodiversity, and species recruitment by installing an outer surface layer composed of biological growth promoting material and of higher surface complexity than armor stone alone (e.g., possibly ECOncrete casts or other types of naturalized features, etc.). The City is still actively investigating the feasibility of integrating ECOncrete armor blocks into the structure to provide ecological Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 74 enhancement to support local species. According to ECOncrete, “The technology helps build up local marine life, supporting the food chain for top predators like seals, and mitigate climate change by storing carbon in calcitic organisms like oysters.” An example successful project is the Living Breakwaters at the Tottenville Shoreline on Staten Island, New Jersey, where armor blocks of ECOncrete were interspersed with eight living breakwaters to protect the shore, provide habitat and public amenities (https://hcr.ny.gov/livingbreakwaters-project-home (New York State 2025). The breakwaters possess thousands of ECOncrete blocks and multiple tide pools enhancing local species supporting the food chain and storing carbon.

The hope would be to mimic conditions of the nearby offshore reef referred to as Seal Rock/Washrock Reef off of Mariposa Point. This reef is 2,000 feet offshore and slightly south of North Beach in water depts of -23 to 28-feet MLLW. Historically, kelp has been prevalent along this section of coastline, but within the last several decades, the canopy has experienced a sharp decline. Other species present in this vicinity that could colonize the breakwater and expand in area include: mussels, gorgonians, keyhole limpets, urchins, sea cucumbers, Kellet's whelk, sea stars, spotted sand bass, kelp bass, senorita, bat rays, and black perch.

Establishment of a living shoreline by the project should not adversely affect existing beach species, and in fact it may complement conditions for beach species by supplying sand to the beach during storms. The vision would be to ultimately provide a continuum of native habitat through entire range of coastal sandy coastal habitats from coastal strand to upper intertidal, midintertidal, and low intertidal areas along the seaward edge of the beach.

3.4.1.9. North Beach Multi-Benefit Emergent Breakwater Concept Summary In summary, the hybrid reef/breakwater proposed at the north end of the City has emerged as a preferred Phase 1 project concept because of the wide variety of benefits the structure would provide for sand retention, coastal access, and shoreline protection purposes. These benefits work synergistically with the unique characteristics specific to North Beach and Capistrano Shores to provide resources such as wider beaches for protection and recreation, new habitat, improved recreation, etc.

The benefits offered by the structure at this location underscore the rationale for its consideration as a preferred project concept and are described below:
• The hybrid reef/breakwater will significantly reduce wave energy and coastal erosion impacting the shore at North Beach and the south end of the Capistrano Shores community.
• Slowing of the longshore sediment transport by the structure will allow for sand accumulation and retention along the shoreline in its lee and immediately up- and downcoast of the structure.
• The prefill of sand behind the structure will establish a revitalized beach for recreation at North Beach and the south end of the Capistrano Shores community. • The sand will offer further protection of the shoreline and adjacent infrastructure by buffering wave energy, especially for structures on the beach such as the public safety building and public restrooms at North Beach and the homes at south Capistrano Shores. • The reef would offer an opportunity to enhance surf resources in an area where the surfing potential is relatively low (though not absent) as determined through the mapping of surf Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 75 sites as part of this project with the assistance, review, and consultation of long-time local surfers. It will be designed to establish a higher-quality surfing resource for varying skill levels.
• A shallow sandy wading/swimming zone with low wave/current energy will be established leeward of the breakwater for beachgoer recreation.
• The surf resources, low energy wading zone, and improved wide, sandy beach will create a draw for tourism and visitation to the beach. This will aid in revitalizing a location that contains unique resources. These include nearby public parking, the City’s primary Metrolink train/bus stop, lifeguard facilities, public safety building, restrooms, fire pits, a tot-lot, and other existing beachside amenities enjoyed by residents and visitors to the City.
• The sandy beach may help establish a new habitat and foraging area for shorebirds and other species. The reservoir of sand at the back of the beach may eventually be able to be used as a living shoreline with plantings to form a dune-type ecosystem in Phase 2 of the project.
• The rocky reef structure will establish a complex, hard-bottom subtidal and intertidal habitat that will attract a higher biodiversity and species richness than is made up by the relatively low quality sandy bottom habitat that currently exists in its proposed footprint.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 76 3.4.2. Concept 2 – Capistrano Shores Multi Benefit Submerged Breakwater and “Speed Bumps”

3.4.2.1. General Overview
Concept 2 is a traditional breakwater proposed to be positioned directly seaward of the middle of the Capistrano Shores community, with two flat, rocky platform “speed bumps/mini-headlands” attached to the shoreline at either end of the reach (Figure 3-2). Compared to the hybrid, emergent reef/breakwaters proposed in the Preferred Concepts 1 and 3, the Capistrano Shores Breakwater would be mainly submerged and longer, but linear in planform and narrower in width. The linear planform could be varied slightly with angled ends to reduce rock quantity by keeping the depth of the breakwater toe shallower than if it were in a straight alignment. This could result in an overall smaller areal footprint on the seafloor of the structure in comparison to the other two concepts, depending on its water depth. The speed bump/mini-headland concepts are similar to those proposed by the City of Oceanside in their Re:Beach Project (International Coastal Management 2023) and could be added to any of the structures proposed in the City as an additional element to help widen the beach.

Figure 3-2: Conceptual Schematic for Concept 2 – Capistrano Shores Multi-Benefit Submerged Breakwater and “Speed Bumps” Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 77 The structure would be situated parallel to the shoreline and located offshore approximately 1,500 feet in water that is 15-20 feet deep. It would be designed to form a salient, or a bulge in the beach in its lee, caused by slowing of longshore sediment transport and decreased incident wave energy landward of the structure. It would create both recreational, coastal public lateral access and habitat opportunities and locally protect the community shoreline, which currently and historically has experienced significant beach erosion that has threatened the existing structures.

The rocky platform speed bumps/mini-headlands situated at either end of the reach would be placed to further slow alongshore littoral drift.

Although direct benefits will occur at Capistrano Shores, indirect benefits should also occur to adjacent beaches at Shorecliffs and North Beach. Sand added to this reach will spill over into the nearby beaches and provide beach widening benefits there which could help serve to establish living shorelines at both Shorecliffs and North Beach that already have vegetation at the back of the beach.

3.4.2.2. Site-Specific Opportunities
Little to no dry sandy beach currently fronts Capistrano Shores above the high tide line and the homes within this beachfront community are under threat from coastal erosion and flooding. The 90 residences that make up the Capistrano Shores community are the only residential buildings/structures in San Clemente built to the west of the OCTA railroad line. However, there is a similar beachfront community located to the north in Dana Point.

Due to the imminent threat of continued shoreline erosion and property damage to these existing structures, this is one of the most critical areas along the San Clemente shoreline needing intervention. Real estate values in this part of the City are among the highest, and the City counts significantly on property taxes for its general operating budget to maintain Citywide services.

Thus, installing a sand retention feature and widening the beach could greatly benefit the entire community and entire City via providing enhanced protection from coastal erosion and recreational beach use.

The homes within the Capistrano Shores community are situated on private land parcels and access to the shoreline for the public is available from North Beach or Poche/Shorecliffs Beach on either end of the community. Establishing and maintaining a wide sandy beach in front of the Capistrano Shores community would restore and enhance lateral access along this stretch of shoreline and create a recreation area for beachgoers via the adjacent coastal access points with significant public parking and transit access that exists at North Beach immediately to the south.

The speed bumps/mini-headlands installed at either end of the beach would provide public access points and overlooks and may provide a localized increase in beach area in their immediate vicinity as well as serve their primary function to retain a wider beach and restore lateral access in the northern part of the City. This effect may occur by encouraging sand settlement around them as well as from sand accumulation behind the breakwater. As a result, the lateral beach access may improve for the general public allowing residents and visitors to walk along the beach in an uninterrupted manner from north to south.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 78 The City’s primary OCTA/Metrolink train stop is located near North Beach, offering public transit to the local beach for beachgoers. Having a larger usable public beach in this vicinity that is accessible from the North Beach Metrolink stop could increase beach attendance/visitation. In addition, the City is currently revitalizing North Beach and the surrounding Los Molinos District to increase tourism, commercial businesses, hotels, restaurants, and attractions in this area.

Concurrently improving the beach would help maintain the shoreline in this general area, boost recreation, improve habitat conditions, and protect infrastructure from coastal hazards. This would serve as a significant supplement to the City’s community enhancement effort already underway.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 79 3.4.2.3. Preliminary Design Elements: Dimensions, and Position and Pre-Fill Volume The breakwater would be approximately 2,000 feet long and 100 feet wide along its length. The breakwater would also be considered “mainly submerged” with a top elevation of the crest of the structure at approximately 0 feet NAVD88. As a result, the structure would not be visible from the shoreline (i.e., does not penetrate the water surface under calm seas conditions) other than during spring low tides when it may extend up to 2 feet above the water surface. Table 3-3 shows the properties of this concept.

Table 3-3: Summary of Capistrano Shores Concept Characteristics Concept Function Position/
Depth Planform Dimensions Crest Height Sand Quantity Added New Beach
Area Created
Capistrano
Shores MultiBenefit
Submerged
Breakwater
Partially block
wave energy,
create a beach,
and establish
intertidal and
subtidal
hard-bottom
habitat
Slightly
deeper at -15
to -20 feet;
located 1,500
feet offshore
Linear crest
and outline;
potentially add
angled ends to
reduce rock
quantity
needed
2,000 feet long
and 100 feet
wide
0 feet NAVD or
mostly
submerged
except at
extreme low tide
600,000-700,000
cubic yards 14 acres
The structure would be positioned approximately 1,500 feet offshore from the middle of the community in order to form a salient on the beach in its lee, similar to that described for the Preferred Concept 1. The structure would be placed in approximately 15-20 feet of water. It would be oriented parallel to shore along its entire length, or could possess slightly angled ends to reduce rock quantity needed for construction.

The speed bumps/mini-headlands at each end of the reach would be designed to slow littoral drift and keep sand behind the breakwater on the shore. These would be located along the shoreline at the ends of the community. They are proposed to be semi-circular in planform with dimensions of 150 feet alongshore and 50 feet shore-normal. They would be constructed with slopes of armor stone and a top filled with sand-sized material. The top of the platforms would reach approximately +16 feet NAVD88 in elevation.

Sand would be used to “pre-fill” the salient (item number “2” in Figure 3-2) to prevent littoral drift from accumulating in the deposit causing deprivation to the downcoast beach. The salient could be nearly 300 feet wide at its widest point and taper back to the existing pre-project shoreline position near the rocky speed bumps/mini-headlands on either end. This area would encompass approximately 600,000 square feet of new beach space (14 acres). The amount of prefill material needed to achieve this profile along this stretch would be approximately 600,000-700,000 cubic yards of sand which would create approximately 14 acres of new beach area.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 80 3.4.2.4. Planning, Engineering, and Design Phases
Like the previous alternative, this project will need to be planned, engineered, and designed prior to implementation. The planning tasks consist of preliminary engineering to conduct environmental review under the CEQA and permitting. After CEQA/NEPA and permitting are completed, the final engineering can occur for construction. Engineering will include numerical modeling of the performance of the project for design refinements, and then physical modeling of it in a laboratory to prove the concept. All of this information will be incorporated into the final engineering documents for construction.

3.4.2.5. Construction, and Performance Monitoring
The breakwater would be constructed out of large armor stone sufficient to remain stable during design storm wave events. The exact size of stone required would be developed during the preconstruction and design engineering phase which would follow the current Feasibility Study phase. In addition, the feature could be modified or raised to provide continued protection under rising seas.

Conversely, if there are negative effects to the adjacent shoreline or safety concerns as a result of its construction then the project could be modified using adaptive management protocols which include refining the structure by raising or lowering it or scattered it over the seabed. It could be dismantled and/or spread out along the nearshore seabed to provide new hard-bottom subtidal habitat or be fully removed from the site using marine construction equipment. Logistics of monitoring are addressed below.

Logistics of Monitoring
Shoreline monitoring includes measuring beach profiles and recording ortho-rectified aerial images for the beach to a position up-and downcoast where no shoreline effects are discernible.

This project specifically proposes to add sand to the littoral cell to compensate for the sand-retaining function of the breakwater. The quantity of sand proposed is more than the volume to be retained to that the entire length of Capistrano Shores can be nourished, and sand can also be contributed to the adjacent shoreline areas both up- and downcoast. Monitoring will extend north and south an appropriate distance to capture adjacent effects, and potential adaptive management actions could include nourishing neighboring beaches to compensate for any project-related impacts.

Biological monitoring would need to be done in the field with surveys of the beach for habitat, and a combination of drone images and SCUBA diving for the ecological conditions of the breakwater.

Results of the monitoring would be used to determine if the project performed as intended (to retain a beach without causing long-term environmental impacts) or needs to be modified to improve/optimize its performance using adaptive management protocols. For example, the breakwater could be lengthened and/or raised to provide continued protection under rising seas.

Biological monitoring would clarify whether plant and animal species have colonized the structure and whether additional ECOncrete units need to be added to the breakwater to increase colonization. Also, beach ecology could be evaluated to determine how the added beach affected sand dwelling organisms and species that feed on them.

Conversely, if the post-construction monitoring were to show that there are negative effects to the adjacent shoreline or safety concerns as a result of its construction then the structure could be Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 81 modified using adaptive management protocols such as removal, or being scattered over the seabed. It could be dismantled and/or spread out along the nearshore seabed to provide new hard-bottom subtidal habitat or be fully removed from the site using marine construction equipment.

3.4.2.6. Shoreline Enhancement Benefits
Similar to the previous alternative, this project would widen the beach along Capistrano Shores each over a distance of 3,700 feet to a maximum of 300 feet behind the breakwater. This sand beach would provide added protection to the backshore, recreational play area of up to 14 acres, and new sandy beach habitat where it does not presently exist. The beach should be stable and persist over most conditions throughout the year and into the distant future, but because it is partially submerged there will be times when the beach is reduced in area due to exposure to waves. However, this location is restricted to access from only the south and north ends of the residential area, so it is less directly available to the public. Protection of the homes is a major benefit from the widened beach, as well as providing a lateral access pathway from North Beach to the northern City limits near Shorecliffs if the beach persists. This is significant in that access between these two points has long since been unavailable to the City since beaches have narrowed.

The definition of success for Capistrano Beach shoreline protection is that:
• the beach reaches 250 feet wide at its apex (widest point), • narrows but continues to exist during severe coastal storm conditions (e.g., 5- to 10-year wave event) to protect the backshore, and
• recovers after storms back to a 250-foot width.

Sea Level Rise
At Capistrano Shores, as sea level rises the beach will gradually retreat with the rate of rise.

According to the Bruun Rule (Bruun 1954 and 1962) if climate change affects only the sea level, while leaving the wave climate unchanged, Bruun reasoned that the slope of the equilibrium shoreface profile then should also remain the same. The profile should move landward and upward, however, to keep the same position with respect to sea level as before. However, this theory assumes that sand is available landward of the beach to nourish the beach as water rises, which may or may not be case throughout San Clemente. Hard backstop exists at Capistrano Shores.

Therefore, if there is no sand supply from landward sources, sea level rise will lead to a gradual ongoing submergence of the subaerial beach, starting with beach lowering adjacent to the sea wall or hard backstop (Beuzen, et al. 2018). To counteract this process, the breakwater will act to artificially keep the beach wide enough to delay its recession landward toward the hard backstop.

However, renourishment will be required eventually to completely offset the landward recession of this beach during sea level rise. Theoretically, with sufficient renourishment and the wave shadowing benefits of the submerged breakwater, this beach should be able to exist for the longterm future of 50 to 75 years or more.

The Public Trust Boundary
The boundary between the State and the City and private properties along beaches is the MHTL.

It is the legal boundary referred to as the public trust boundary. This is the line on the shoreline Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 82 that the water reaches during a mean high water event. That line is equivalent to an approximate elevation of 4.75 feet above mean lower low water, or the 0.0 value on a tide chart or in a tide book. The MHTL is a line that shifts with changes to the position of the shoreline, meaning that beach nourishment and sand retention can cause the boundary to shift farther away from shore if beaches become wider.

The State of California owns land seaward (to the west) of the MHTL toward the ocean, while the Capistrano Shores Manufactured Home Community owns the beach landward (to the east) of the MHTL at this site. As such, the effects of beach nourishment and sand retention typically result in the MHTL shifting seaward which would cause the Community to own more of the beach.

Typically, the State requires a MHTL survey prior to the nourishment project as part of permitting so that the boundary can be set and remain unchanged in the future after nourishment, so in reality the line will likely not change in landownership documents but may show a shift on the ground.

This alternative would shift the MHTL shoreline seaward to occupy approximately the seaward boundary of the eventual shoreline shown in Figure 3-2 for this alternative.

3.4.2.7. Recreation and Public Access Benefits
Locating the breakwater offshore in front of Capistrano Shores would effectively dissipate a large proportion of wave energy on the structure instead of closer to or directly on the shoreline. Since there are no known quality surfing resources fronting the Capistrano Shores community, the installation of the breakwater would not result in any diminished surfing opportunity as a result of the structure itself. The formation of the salient and sand accumulation leeward of the breakwater should establish a shallower bottom and wading/swimming area with reduced wave energy behind the structure. However, since the breakwater is designed as a submerged structure, some amount of wave energy will reach the shoreline creating conditions for smaller wave surfing.

Other forms of recreation will be improved with a wider beach as well. The beach will provide area for walking, sunbathing, swimming, sightseeing, fishing and collecting. The quiet water zone behind the breakwater may provide an opportunity for SCUBA diving in that it provides a safer entry/exit to and from the water on most days compared to existing conditions. A relatively short swim by a diver could enable them to reach the breakwater and dive around its perimeter to view sea life along the structure.

Annual beach visitation will very likely increase in numbers because it is typically constrained by towel space on the beach and the project will significantly increase that component. This site is less accessible to visitors both local and distant than North Beach, so improved access may need to be provided to render it as a public benefit. Examples may include applying property taxes from this specific Community to maintain or improve access or recreational opportunities nearby, or to provide more on-site vertical access points at this location.

3.4.2.8. Ecological Benefits
At the location of the proposed breakwater, existing available survey and aerial photography data suggest that a significant proportion of the seafloor is relatively flat and has a sandy layer. Existing offshore site conditions would be mapped in the next phase of the project for this site if it were to move forward. The ecology of the project includes mainly intertidal and subtidal sandy habitat, some patchy subtidal hard bottom habitat, and very little sandy beach habitat. Each habitat type is addressed below. The project site was evaluated in general by Merkel & Associates (M&A) in 2025 for the County’s SCOUP. This section is borrowed from that report.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 83 Intertidal and Subtidal Sandy Beach Habitat
The offshore sandy bottom habitat type of Capistrano Shores is described in the M&A report (2025) with the information below.

The subtidal zone is classified into general regions, including the shallow subtidal to a depth of about -30 feet MLLW (generally corresponds to littoral zone), an inner shelf zone from about -30 to -80 feet MLLW, middle shelf from about -80 to -300 feet MLLW, and outer shelf zone from about -300 to -600 feet MLLW. The study area for this Project focuses on the shallow subtidal region or to the depth of closure.

Bottom-dwelling invertebrate species in the shallow subtidal zone are well adapted to shifting sediments and turbidity, with suspension feeders being the dominant group. Many of the sandy beach invertebrates move between the intertidal and shallow subtidal depths and additional species live on and within sediments within increasing distance offshore as wave energy diminishes toward the seaward limit of the littoral zone. Common species in the shallow subtidal zone of the Capistrano Shores project area include burrowing anemones, sea pansy, sea pen, purple globe crab (Randallia ornata), clams, snails, sand dollar, sea star, and tube worms (SAIC 2011). Fish commonly found in shallow subtidal habitat (less than 30 feet) off southern California beaches include California halibut (Paralichthys californicus), barred surfperch (Amphistichus argenteus), yellowfin croaker (Umbrina roncador), speckled sanddab (Citharichthys stigmaeus), California bat ray (Myliobatus californica), shovelnose guitarfish (Rhinobatos productus). northern anchovy (Engraulis mordax), jack mackerel (Trachurus symmetricus), round ray (Urobatus halleri), walleye surfperch (Hyperprosopon argenteum), leopard shark (Triakis semifasciata), spotfin croaker (Roncador stearnsii), and topsmelt (Atherinops affinis).

Subtidal Hard Bottom Habitat
M&A (2025) further describes the subtidal hard bottom habitat with the information below.

Hard-bottom habitats are productive ecosystems that support a variety of plants and animals.

They include rocky intertidal shores and nearshore reefs, and support vegetated habitats such as surfgrass and kelp beds. Rocky habitats are localized in the Project Area and may vary depending on physical characteristics and degree of sand influence. Reef height and complexity are primary factors associated with habitat quality (AMEC 2005) (SANDAG 2011) (SAIC 2011). Low-lying reefs subject to sand scour support few biological resources while reefs that extend above the height of seasonal sand movement generally support diverse communities of invertebrates, fish, and vegetation.

Biological resources in the intertidal vary with exposure, relief height and complexity. The upper intertidal or splash zone is characterized by simple green algae (Chaetomorpha spp., Enteromorpha spp., Ulva spp.), barnacles (Cthamalus spp.), limpets (Lottia spp.), and periwinkles (Littorina spp.). Intertidal areas not influenced by sand burial and abrasion often support California mussel (Mytilus californus), gooseneck barnacle (Pollicipes polymerus), aggregating sea anemones (Anthopleura elegantissima), hermit crabs (Pagurus spp.), striped shore crab (Pachygrapsus crassipes), snails (e.g., Lithopoma spp., Kelletia kellitia, Tegula spp.), and chitons (Mopalia mucosa, Nutallina spp.) (Blanchette et al. 2015). Coralline algae, crusts, and red algal turf are common on low-relief substrate subject to sand influence.

Hard substrate in the low tidal zone and minus tide zone are characterized by a greater diversity of plants and animals including coralline algae, other red algae, brown algae, surfgrass, green sea anemones (Anthopleura xanthogrammica), purple sea urchins, California sea hares (Aplysia Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 84 californica), snails, sponges, and starfish (Asterina miniata, Pisaster spp.). Wooly sculpin (Clinocottus analis) is one of the more commonly encountered fish in tidepools.

Subtidal reefs in the shallow nearshore also exhibit considerable variation in resource development associated with the seasonal onshore and offshore migration of sand. Similar to intertidal reefs, substrate factors such as relief height, texture, composition, and size largely determine resource development. Understory algae are common on nearshore reefs and feather boa kelp (Egregia menzesii) is conspicuous, growing up to 12 feet in length. The sea palm (Eisenia arborea) may co-occur with feather boa kelp at subtidal depths (AMEC 2005, SAIC 2006a, SAIC 2007). A variety of red algae (Corallina spp., Gigartina spp., Gracilaria spp., Jania spp., Lithothrix spp. Rhodoymenia spp.) and brown algae (Cystoseira osmundacea, dictyotales, Zonaria farlowi) may co-occur with feather boa kelp and/or sea palms on nearshore reefs.

Persistent reefs support hundreds of species of invertebrates (e.g., crabs, nudibranchs, sea urchins, scallops, sea stars, snails, sponges, tunicates, worms) and attract a variety of fish such as garibaldi (Hypsypops rubicundus), blacksmith (Chromis punctipinnis), and black perch (Embiotoca jacksoni).

Moving farther offshore to depths where seasonal sand movement is less, hard substrates do not need to have as high a relief to support perennial species. Giant kelp (Macrocystis pyrifera) attaches to hard substrate by means of a holdfast, and fronds may grow to heights that exceed the water depth, forming leafy canopies at the water surface. Kelp forests are among the most productive marine habitats along the coast of California providing habitat, feeding grounds, and nursery areas for many species of fishes, invertebrates, and marine mammals. The kelp community in the Project Area is dominated by giant kelp, which ranges from water depths of about -20 feet to -80 feet MLLW. Kelp beds in southern California commonly deteriorate to some degree during summer and fall when temperatures are higher and nutrient concentrations are lower. Giant kelp is adversely affected by sedimentation and turbidity (Foster and Schiel 1985).

Large amounts of shifting sediment can bury small plants and prevent the settling of microscopic spores, both of which can affect kelp beds. El Niño conditions which result in high waves, higher-than-average temperatures, and low nutrients, have been linked to periodic and widespread reductions in kelp canopy (Foster and Schiel 1985).

Invertebrates found in kelp beds include lobster (Panuliris interruptus), sea stars, sea urchins, and mollusks. Surfperch, rockfish (Sebastes spp.), cabezon (Scorpaenichthys marmoratus), kelp bass (Paralabrax clathratus), and wrasses (senorita, rock wrasse, and sheephead) are also commonly observed in southern California kelp beds.

Reef quality or the ability to support sediment-influenced indicator species is directly correlated with reef elevation (i.e., height of the reef), as higher-relief reefs are more resistant to sedimentation and scour, and therefore, allows perennial species to persist (AMEC 2005). Reef heights in relatively higher quality areas generally include a greater percentage of heights >1 feet (0.3 meters) compared to relatively lower quality areas. The study of nearshore reefs in San Diego County noted other relationships between indicator species occurrence and reef heights and suggested that it appeared to be influenced by depth distribution (SAIC 2007). Several examples included:
• Surfgrass, which primarily occurred at water depths ≤15 feet (5 meters), was uncommon on reef heights <1 feet (0.3 meters) and had denser cover on substrate heights ≥2 feet (0.6 meters) than on 1 feet (0.3 meters) heights.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 85 • Giant kelp primarily occurred at water depths >15 feet (5 meters) on reef heights ≥1 feet (0.3 meters). Giant kelp had sparse occurrence on nearshore reefs. Primary kelp canopies occurred further offshore beyond the depth of closure.
• Sea palm and feather boa understory algae occurred mainly at water depths <26 feet (8 meters), with a similar or greater number of records between 15 and 26 feet (5 and 8 meters). Both species had greater cover on reef heights >1 feet (0.3 meters) (Merkel & Associates, Inc. 2025).
• Sea fan occurrence increased with depth, with most records at depths >26 feet (8 meters).

Although sea fans mainly occurred on substrate ≥1 feet (0.3 meters) high, there were more records on reefs <1 feet (0.3 meters) in height than observed for other indicator species, most likely related to less sand influence with increasing depth. • Hard substrate with opportunistic turf algae, sparse occurrence of opportunistic feather boa kelp, and/or lacking vegetation has been used to distinguish substantially sand influenced (scoured) reef.

Sandy Beach Habitat
In addition, beach nourishment would definitely serve to increase the area of sandy beach habitat at this location. It does not include a living shoreline due to the lack of potential to establish one at this site owing to its very narrow beach. Establishing a wider beach provides an opportunity for shorebirds, native vegetation, and intertidal infaunal and fish species that inhabit sandy beaches to utilize the space as an expanded local habitat. It may also provide an opportunity for sensitive species (such as grunion) to expand within their regional distribution range.

As described by CRM (2000), existing sandy beach habitat in the area is “…composed of medium to coarse sand with no rocky intertidal habitat along this part of the shoreline. Typical sandy beach organisms (worms, sand crabs, amphipods, isopods, and clams) exist between the low and high tide marks and will vary on a seasonal basis as a result of changes in physical beach characteristics. All of these species are resilient and have life histories based upon high seasonal turnover.”
Future Possibilities
The definition of success for ecology is that:
• the beach possesses the entire range of sub-habitats (upper intertidal, mid-intertidal, and low intertidal) through-out the year across its widest point, and • the submerged breakwater serves as an attraction for marine organism colonization with the typical local species of mussels, gorgonians, keyhole limpets, urchins, sea cucumbers, Kellet's whelk, sea stars, spotted sand bass, kelp bass, senorita, bat rays, and black perch.

The project would be designed to attract marine growth on the hard-bottom material (stone). The proposed reef is proposed to be constructed out of armor rock, situating it in an ecologically less sensitive area of the seafloor to enhance the habitat potential for subtidal and intertidal species colonization and use. The process is intended to function somewhat similar to the SONGS Wheeler Reef mitigation project reef modules located farther offshore in deeper water off of this site. The breakwater structure could also potentially be enhanced to maximize habitat potential, biodiversity, and species recruitment by installing an outer surface layer composed of biological growth promoting material and of higher surface complexity than armor stone alone (e.g., possibly Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 86 ECOncrete casts or other types of naturalized features, etc.). The City is still actively investigating the feasibility of integrating ECOncrete armor blocks into the structure to provide ecological enhancement to support local species. According to ECOncrete, “The technology helps build up local marine life, supporting the food chain for top predators like seals, and mitigate climate change by storing carbon in calcitic organisms like oysters.” An example successful project is the Living Breakwaters at the Tottenville Shoreline on Staten Island, New Jersey, where armor blocks of ECOncrete were interspersed with eight living breakwaters to protect the shore, provide habitat and public amenities (https://hcr.ny.gov/livingbreakwaters-project-home (New York State 2025). The breakwaters possess thousands of ECOncrete blocks and multiple tide pools enhancing local species supporting the food chain and storing carbon.

The vision would be to mimic conditions of the nearby offshore reef referred to as Seal Rock/Washrock Reef. This reef is 2,000 feet offshore and slightly south of North Beach in water depths of -23 to 28-feet MLLW. Historically, kelp has been prevalent along this section of coastline, but within the last several decades, the canopy has experienced a sharp decline. Other species present in this vicinity that could colonize the breakwater and expand in area include:
mussels, gorgonians, keyhole limpets, urchins, sea cucumbers, Kellet's whelk, sea stars, spotted sand bass, kelp bass, senorita, bat rays, and black perch.

Establishing a wider beach leeward of the structure provides an opportunity for shorebirds, native vegetation, and intertidal benthic infaunal species (sand crabs and bean clams) that inhabit sandy beaches to utilize the space as an expanded local habitat. It may also provide an opportunity for sensitive species (grunion), threatened or endangered species (least terns and snowy plovers), and vegetation species to have more space to expand within their regional distribution range.

3.4.2.9. Capistrano Shores Multi Benefit Submerged Breakwater and “Speed Bumps” Concept Summary In summary, the submerged breakwater and speed bumps/mini-headlands located in front of the Capistrano Shores community is a proposed Phase 1 project concept due to the multiple benefits the structure would provide for the area. The residential community would be offered protection from coastal storm damage. In addition, a beach would be reestablished that would restore lateral access in the City and could be utilized by the public for walking and sandy shore-dwelling floral and faunal species.

In summary, the benefits offered by the structure at this location and reasons for its consideration as a preferred concept are as follows:
• The breakwater will significantly reduce wave energy and resultant erosion impacting the shoreline along the extent of the community.
• Slowing of the longshore sediment transport by the structure will allow for sand accumulation and retention along the shoreline in its lee. • Speed bumps/mini-headlands installed as low-lying rocky platforms attached to the shore on either end of the community will interrupt littoral drift, promote sediment accumulation and beach stabilization within their vicinity, and help to retain sand behind the breakwater. • The prefill of sand behind the structure will establish a revitalized beach for recreation and will restore lateral public access.
• The sand will offer protection of the shoreline and existing structures along the extent of shoreline by buffering wave energy that impacts the shoreline.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 87 • A shallow and sandy wading/swimming zone with lower wave energy will be established leeward of the breakwater, enhancing recreation potential for beachgoers. • The expanded wide, sandy beach will create a draw for tourism and visitation. There is abundant nearby public parking and a Metrolink train/bus stop within close vicinity of access to the beach.
• The sandy beach may help establish a new habitat and foraging area for shorebirds and other shore-dwelling species.
• The breakwater structure will establish a complex, hard-bottom subtidal and intertidal habitat that will attract much higher biodiversity and species richness than the relatively low quality low-relief sandy or reef seabed that currently exists.

3.4.3. Concept 3 – State Beach Multi-Benefit Emergent Breakwater

3.4.3.1. General Overview
Concept 3 is similar to the emergent rocky reef/breakwater hybrid structure proposed for Concept 1; however, it would be sited at the south end of the City at a critically eroded beach (Moffatt & Nichol 2023). It would be located straddling the boundary between the San Clemente State Beach and Cyprus Shore at the south end of the City with the majority of the project on State land (Figure 3-3). Similar to Concept 1 at North Beach, this structure would be constructed of armor stone material and have a “barbell” planform design. The structure would be located approximately 600 feet offshore in 15 feet of water. The structure is also located offshore of OCTA Reinforcement Area 4.

The submerged flared sides of the structure would gently slope down around the seaward and side edges to provide a recreational surfing resource, while the main body of the structure would have steeper slopes shoreward and seaward to dissipate wave energy. The crest along the top of the reef/breakwater would be emergent at all times. This concept was adapted from the City of Oceanside Sand Replenishment and Sand Retention Project (GHD 2021). As mentioned previously herein, two other project concepts are being considered elsewhere (Oceanside for Re:Beach by the City of Oceanside and at Pacifica by a citizens group) and the City is keeping abreast of developments and changes that could potentially bear on the design of this concept.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 88 Figure 3-3: Conceptual Schematic 3 – State Beach Multi-Benefit Emergent Breakwater Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 89 The structure would be positioned parallel to the shoreline and just offshore of the coast. It would be designed to form a salient, or a bulge in the beach in its lee, caused by slowing of longshore sediment transport and reduction of incident wave energy. It would create both recreational and habitat opportunities and locally protect the south State Beach shoreline and the beach adjacent to the four residential communities at the City’s south end. This area currently and historically has experienced significant beach erosion and undermining that has threatened shoreside infrastructure, particularly the OCTA railway and revetment.

3.4.3.2. Site-Specific Opportunities
Locating this structure at the south end of the San Clemente State Beach has recreational and socioeconomic benefits for State Parks, the City, public beachgoers and visitors, the OCTA, and the residential communities at the south end of the City with increased lateral beach access in the vicinity and larger beach area for recreation due to their proximity.

The local beaches at the south end of the City are actively eroding according to the ongoing shoreline monitoring program results (Coastal Frontiers Corporation 2024). Due to the recently increasing threat of shoreline erosion to the adjacent OCTA railway infrastructure, the transportation agency placed additional armor stone in 2023 and 2024 to fortify its tracks/revetment just south of the proposed location of the reef/breakwater under an Emergency Coastal Development Permit. Establishing a sand retention feature and prefilling the beach would greatly benefit the railway by offering protection from coastal erosion and re-establishing a recreation area for beach users where public access is available via the State Park.

The surf resource opportunities provided by the feature would also likely enhance recreation appeal to the beach and attract City and State Parks visitation and revenue. Finally, the only currently available coastal access point for the southern residential community members (containing 426 homes) known as “North Gate” is repeatedly flooded and has been regularly under threat from coastal erosion in recent years. Placing the hybrid reef/breakwater just upcoast and nourishing the nearby beach would likely offer some protection for this important accessway for the community.

In addition, the widened shoreline may potentially restore beachside access from the southern residential communities to San Clemente State Beach, with the ultimate vision being restoration of lateral coastal access along the beach allowing residents and visitors to once again walk south along the beach from the Pier to Trestles and San Onofre State Beach.

3.4.3.3. Planning, Engineering, and Design Phases
Like the previous alternatives, this project will need to be planned, engineered, and designed prior to implementation. The planning tasks consist of preliminary engineering to conduct environmental review under CEQA and the NEPA and permitting. After CEQA/NEPA and permitting are completed, the final engineering can occur for construction. Engineering will include numerical modeling of the performance of the project for design refinements, and then physical modeling of it in a laboratory to prove the concept. All of this information will be incorporated into the final engineering documents for construction.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 90 3.4.3.4. Preliminary Design Elements: Dimensions, Position and Pre-Fill Volume The shore-parallel, hybrid breakwater/reef would be located at the southern end of the San Clemente State Beach shoreline. The footprint of the “barbell” shaped structure would be approximately 1,300 feet long, 350 feet wide in the center along the mid-point, and 700 feet wide at ends. It would be located approximately 600 feet offshore in order to form a salient, or a bulge in the beach. The majority of the structure would be in a depth of water of between 10-20 feet. Table 3-4 shows the properties of this concept.

Table 3-4: Summary of State Beach Concept Characteristics Concept Function Position/
Depth Planform Dimensions Crest Height Sand Quantity
New Beach
Area Created
State Beach
Multi-Benefit
Emergent
Breakwater
Block wave
energy, create
surfing site and
a beach;
establish
intertidal and
subtidal
hard-bottom
habitat
Shallow
nearshore -
15 feet;
located 600
feet offshore
Linear crest with
rounded ends
(barbell)
1,300 feet long;
350 feet wide;
700 feet widened
and rounded
ends
+10 feet NAVD
or emergent at
all times, with
sloping
shoulders
500,000 to
600,000
cubic yards
8-12 acres
The crest would be approximately 1,000 feet long and 130 feet wide and be emergent (visible) at all times. The crest would be doglegged at approximately 45 degrees towards shore for the last 200 feet at each end and constructed to an elevation of +10 feet NAVD88. This implies that under current sea level conditions, at the lowest spring tides about 11-12 feet of the breakwater crest would be exposed and at the highest spring tides approximately 2-3 feet of the breakwater crest would be exposed.

A prefill of sand would be placed (item number “2” in Figure 3-3) that mimics the anticipated salient extent that would eventually form leeward of the structure. Sand pre-filling of the salient is done to prevent littoral drift from accumulating in the deposit causing deprivation to the downcoast beach. The prefill would be shaped to form a beach that is approximately 300 feet wide at its widest point directly behind the breakwater, tapering down eventually to meet the existing pre-project shoreline position beyond the protective shadow of the structure. This would likely encompass an area that is approximately 12 acres in size, thus requiring about 700,000-800,000 cubic yards of sand material as pre-fill. Although their sand volumes are listed as being the same, a slightly larger quantity of sand may be required at this site compared to North Beach for the same concept because bathymetry is lower offshore at this site compared to North Beach thus requiring more sand to create the new beach.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 91 3.4.3.5. Construction and Performance Monitoring
The hybrid breakwater/reef is proposed to be constructed out of armor stone, with the specific sizes to be determined by future engineering efforts. The exact size of stone required would be developed during the pre-construction and design engineering phase which would follow the current Feasibility Study phase. In addition, the feature could be modified or raised to provide continued protection under rising seas.

Conversely, if there are negative effects to the adjacent shoreline, lack of benefits (beach building performance) or safety concerns as a result of its construction then the quarry stone could be removed or scattered over the seabed. It could be dismantled and/or spread out along the nearshore seabed to provide new hard-bottom subtidal habitat or be fully removed from the site using marine construction equipment. Logistics of monitoring are addressed below.

Logistics of Monitoring
Shoreline monitoring includes measuring beach profiles and recording ortho-rectified aerial images for the beach to a position up-and downcoast where no shoreline effects are discernible.

This project specifically proposes to add sand to the littoral cell to compensate for the sand-retaining function of the breakwater. The quantity of sand proposed is more than the volume to be retained so that the entire State Beach can be nourished and sand can also be contributed to the adjacent shoreline areas both up- and downcoast. Monitoring will extend north and south an appropriate distance to capture adjacent effects, and potential adaptive management actions could include nourishing neighboring beaches to compensate for any project-related impacts.

Wave monitoring can be done using camara images from a stationary position over time using Surfline AI for analyses combined with surveys of local surfers.

Biological monitoring would need to be done in the field with surveys of the beach and backshore for habitat, and a combination of drone images and SCUBA diving for the ecological conditions of the breakwater.

Results of the monitoring would be used to determine if the project performed as intended (to retain a beach without causing long-term environmental impacts) or needs to be modified to improve/optimize its performance using adaptive management protocols. For example, the breakwater could be lengthened and/or raised to provide continued protection under rising seas.

Biological monitoring would clarify whether plant and animal species have colonized the structure and whether additional ECOncrete units need to be added to the breakwater to increase colonization. Also, beach ecology could be evaluated to determine how the added beach affected sand dwelling organisms and species that feed on them. Also, surfing monitoring could document changes to surfing conditions at this location. If surfing is not possible or considered of moderate quality, then either the slopes of the breakwater ends could be modified to create a better quality surfing experience.

3.4.3.6. Shoreline Enhancement Benefits
This project would widen the State Beach over a distance of 1,500 feet to a maximum of 350 feet behind the breakwater. This sand beach would provide added protection to the backshore, recreational play area of approximately 12 acres, and new sandy beach habitat where it does not presently exist. The beach should be stable and persist over near all conditions throughout the year and into the distant future, thus providing a dependable resource for the City to enjoy.

Protection of the railroad and active landslide toe are major benefits from the widened beach.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 92 This new beach could potentially provide a near-constant access along beach from San Onofre State Beach in the south to San Clemente State Beach in the north. The definition of success for shoreline protection is that:
• the beach reaches 250 feet wide at its apex (widest point), • narrows but continues to exist during severe coastal storm conditions (e.g., 5- to 10-year wave event) to protect the backshore, and
• recovers after storms back to a 250-foot width.

Sea Level Rise
Sea level rise will affect all features along the coast including San Clemente’s project sites. At North Beach, as sea level rises the beach will gradually retreat with the rate of rise. According to the Bruun Rule (Bruun 1954) (Bruun 1962), if climate change affects only the sea level, while leaving the wave climate unchanged, Bruun reasoned that the slope of the equilibrium shoreface profile then should also remain the same. The profile should move landward and upward, however, to keep the same position with respect to sea level as before. However, this theory assumes that sand is available landward of the beach to nourish the beach as water rises, which may or may not be case throughout San Clemente. Hard backstop exists along this southern segment of the State Beach.

Therefore, if there is no sand supply from landward sources, sea level rise will lead to a gradual ongoing submergence of the subaerial beach, starting with beach lowering adjacent to the sea wall or hard backstop (Beuzen, et al. 2018). To counteract this process, the breakwater will act to artificially keep the beach wide enough to delay its recession landward toward the hard backstop.

However, renourishment will be required eventually to completely offset the landward recession of this beach during sea level rise. Theoretically, with sufficient renourishment and the wave shadowing benefits of the breakwater, this beach should be able to exist for the long-term future of 75 years or more.

The Public Trust Boundary
The boundary between the State and the City and private properties along beaches is the MHTL.

It is the legal boundary referred to as the public trust boundary. This is the line on the shoreline that the water reaches during a mean high water event. That line is equivalent to an approximate elevation of 4.75 feet above mean lower low water, or the 0.0 value on a tide chart or in a tide book. The MHTL is a line that shifts with changes to the position of the shoreline, meaning that beach nourishment and sand retention can cause the boundary to shift farther away from shore if beaches become wider.

The State of California owns land both landward and seaward of the MHTL at the majority of this location because it is along the State Beach Park, with a small exception were a property line from Cyprus Shore overlaps the project area. At this specific boundary over, Cyprus Shore owns a portion of the beach landward (to the east) of the MHTL. As such, the effects of beach nourishment and sand retention typically result in the MHTL shifting seaward which would cause Cyprus Shore to own more of the beach. Typically, the State requires a MHTL survey prior to the nourishment project as part of permitting so that the boundary can be set and remain unchanged in the future after nourishment, so the line will likely not change in landownership documents but may show a shift on the ground.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 93 This alternative would shift the MHTL shoreline seaward to occupy approximately the seaward boundary of the eventual shoreline shown in Figure 3-3 for this alternative.

3.4.3.7. Recreation and Public Access Benefits
The hybrid reef/breakwater is designed with a barbell planform shape and sloping submerged edges to focus and refract incoming swell energy in a way that generates a surfing resource opportunity. In doing so, it is designed to create both a left and a right breaking wave on the north and south side of the structure, respectively. For non-surfing visitors, the formation of the salient and sand accumulation leeward of the reef/breakwater would establish a wading area for swimmers. In this zone there would likely be minimal wave energy due to the blocking of surf by the emergent breakwater crest.

The structure would be placed at the southern end of the State Beach and situated in a location that does not impact surfing at nearby North Gate, South Gate, or the primary surf spots along the State Beach shoreline. Similarly, it is intended to be situated a sufficient distance from the high-quality surf resource of Cotton’s Point that it would not have any impacts on the surf quality of that site or at Trestles located further downcoast around San Mateo Point.

The prefill and anticipated sand accumulation of this feature is intended to be a sufficient distance from all notable surf breaks to avoid any long-term or permanent changes in nearshore bathymetry that may negatively affect nearby surfing resources. In effect, the hybrid reef/breakwater structure would be designed to enhance local surfing resource opportunities where it is sited.

Other forms of recreation will be improved with a wider beach as well. The beach will provide area for walking, sunbathing, swimming, volleyball, sightseeing, fishing and collecting. The quiet water zone behind the breakwater may provide an opportunity for SCUBA diving in that it provides a safe entry/exit to and from the water on most days. A relatively short swim by a diver could enable them to reach the reef and dive around its perimeter to view sea life along the structure.

Annual beach visitation will very likely increase in numbers because it is typically constrained by towel space on the beach and the project will significantly increase that component. Also, ample parking and public transit exist at this site, so it is very accessible to visitors both local and distant.

Finally, public access all along the beach connecting San Clemente State Beach to San Onofre State Beach could be realized thus restoring a major beach front access route as existed prior to 2014.

3.4.3.8. Ecological Benefits
At the location of the proposed breakwater, existing available survey and aerial photography data suggest that a significant proportion of the seafloor is relatively flat and has a sandy layer. Existing offshore site conditions would be mapped in the next phase of the project for this site if it were to move forward. The ecology of the project includes mainly intertidal and subtidal sandy habitat, some patchy subtidal hard bottom habitat, and very little sandy beach habitat. Each habitat type is addressed below. The project site was evaluated in general by Merkel & Associates (M&A) in 2025 for the County’s Sand Compatibility and Opportunistic Use Program (SCOUP). This section is borrowed from that report.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 94 Intertidal and Subtidal Sandy Beach Habitat
The offshore sandy bottom habitat type of State Beach is described in the M&A report (2025) with the information below.

The subtidal zone is classified into general regions, including the shallow subtidal to a depth of about -30 feet MLLW (generally corresponds to littoral zone), an inner shelf zone from about -30 to -80 feet MLLW, middle shelf from about -80 to -300 feet MLLW, and outer shelf zone from about -300 to -600 feet MLLW. The study area for this Project focuses on the shallow subtidal region or to the depth of closure.

Bottom-dwelling invertebrate species in the shallow subtidal zone are well adapted to shifting sediments and turbidity, with suspension feeders being the dominant group. Many of the sandy beach invertebrates move between the intertidal and shallow subtidal depths and additional species live on and within sediments within increasing distance offshore as wave energy diminishes toward the seaward limit of the littoral zone. Common species in the shallow subtidal zone of the project area include burrowing anemones, sea pansy, sea pen, purple globe crab (Randallia ornata), clams, snails, sand dollar, sea star, and tube worms (SAIC 2011). Fish commonly found in shallow subtidal habitat (less than 30 feet) off southern California beaches include California halibut (Paralichthys californicus), barred surfperch (Amphistichus argenteus), yellowfin croaker (Umbrina roncador), speckled sanddab (Citharichthys stigmaeus), California bat ray (Myliobatus californica), shovelnose guitarfish (Rhinobatos productus), northern anchovy (Engraulis mordax), jack mackerel (Trachurus symmetricus), round ray (Urobatus halleri), walleye surfperch (Hyperprosopon argenteum), leopard shark (Triakis semifasciata), spotfin croaker (Roncador stearnsii), and topsmelt (Atherinops affinis).

Subtidal Hard Bottom Habitat
M&A (2025) further describes the subtidal hard bottom habitat with the information below.

Hard-bottom habitats are productive ecosystems that support a variety of plants and animals.

They include rocky intertidal shores and nearshore reefs, and support vegetated habitats such as surfgrass and kelp beds. Rocky habitats are localized in the Project Area and may vary depending on physical characteristics and degree of sand influence. Reef height and complexity are primary factors associated with habitat quality (AMEC 2005) (SAIC 2011) (SANDAG 2011). Low-lying reefs subject to sand scour support few biological resources while reefs that extend above the height of seasonal sand movement generally support diverse communities of invertebrates, fish, and vegetation.

Biological resources in the intertidal vary with exposure, relief height and complexity. The upper intertidal or splash zone is characterized by simple green algae (Chaetomorpha spp., Enteromorpha spp., Ulva spp.), barnacles (Cthamalus spp.), limpets (Lottia spp.), and periwinkles (Littorina spp.). Intertidal areas not influenced by sand burial and abrasion often support California mussel (Mytilus californus), gooseneck barnacle (Pollicipes polymerus), aggregating sea anemones (Anthopleura elegantissima), hermit crabs (Pagurus spp.), striped shore crab (Pachygrapsus crassipes), snails (e.g., Lithopoma spp., Kelletia kellitia, Tegula spp.), and chitons (Mopalia mucosa, Nutallina spp.) (Blanchette et al. 2015). Coralline algae, crusts, and red algal turf are common on low-relief substrate subject to sand influence.

Hard substrate in the low tidal zone and minus tide zone are characterized by a greater diversity of plants and animals including coralline algae, other red algae, brown algae, surfgrass, green sea anemones (Anthopleura xanthogrammica), purple sea urchins, California sea hares (Aplysia Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 95 californica), snails, sponges, and starfish (Asterina miniata, Pisaster spp.). Wooly sculpin (Clinocottus analis) is one of the more commonly encountered fish in tidepools.

Subtidal reefs in the shallow nearshore also exhibit considerable variation in resource development associated with the seasonal onshore and offshore migration of sand. Similar to intertidal reefs, substrate factors such as relief height, texture, composition, and size largely determine resource development. Understory algae are common on nearshore reefs and feather boa kelp (Egregia menzesii) is conspicuous, growing up to 12 feet in length. The sea palm (Eisenia arborea) may co-occur with feather boa kelp at subtidal depths (AMEC 2005, SAIC 2006a, SAIC 2007). A variety of red algae (Corallina spp., Gigartina spp., Gracilaria spp., Jania spp., Lithothrix spp. Rhodoymenia spp.) and brown algae (Cystoseira osmundacea, dictyotales, Zonaria farlowi) may co-occur with feather boa kelp and/or sea palms on nearshore reefs.

Persistent reefs support hundreds of species of invertebrates (e.g., crabs, nudibranchs, sea urchins, scallops, sea stars, snails, sponges, tunicates, worms) and attract a variety of fish such as garibaldi (Hypsypops rubicundus), blacksmith (Chromis punctipinnis), and black perch (Embiotoca jacksoni).

Moving farther offshore to depths where seasonal sand movement is less, hard substrates do not need to have as high a relief to support perennial species. Giant kelp (Macrocystis pyrifera) attaches to hard substrate by means of a holdfast, and fronds may grow to heights that exceed the water depth, forming leafy canopies at the water surface. Kelp forests are among the most productive marine habitats along the coast of California providing habitat, feeding grounds, and nursery areas for many species of fishes, invertebrates, and marine mammals. The kelp community in the Project Area is dominated by giant kelp, which ranges from water depths of about -20 feet to -80 feet MLLW. Kelp beds in southern California commonly deteriorate to some degree during summer and fall when temperatures are higher and nutrient concentrations are lower. Giant kelp is adversely affected by sedimentation and turbidity (Foster and Schiel 1985).

Large amounts of shifting sediment can bury small plants and prevent the settling of microscopic spores, both of which can affect kelp beds. El Niño conditions which result in high waves, higherthan-average temperatures, and low nutrients, have been linked to periodic and widespread reductions in kelp canopy (Foster and Schiel 1985).

Invertebrates found in kelp beds include lobster (Panuliris interruptus), sea stars, sea urchins, and mollusks. Surfperch, rockfish (Sebastes spp.), cabezon (Scorpaenichthys marmoratus), kelp bass (Paralabrax clathratus), and wrasses (senorita, rock wrasse, and sheephead) are also commonly observed in southern California kelp beds.

Reef quality or the ability to support sediment-influenced indicator species is directly correlated with reef elevation (i.e., height of the reef), as higher-relief reefs are more resistant to sedimentation and scour, and therefore, allows perennial species to persist (AMEC 2005). Reef heights in relatively higher quality areas generally include a greater percentage of heights >1 feet (0.3 meters) compared to relatively lower quality areas. The study of nearshore reefs in San Diego County noted other relationships between indicator species occurrence and reef heights and suggested that it appeared to be influenced by depth distribution (SAIC 2007). Several examples included:
• Surfgrass, which primarily occurred at water depths ≤15 feet (5 meters), was uncommon on reef heights <1 feet (0.3 meters) and had denser cover on substrate heights ≥2 feet (0.6 meters) than on 1 feet (0.3 meters) heights.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 96 • Giant kelp primarily occurred at water depths >15 feet (5 meters) on reef heights ≥1 feet (0.3 meters). Giant kelp had sparse occurrence on nearshore reefs. Primary kelp canopies occurred further offshore beyond the depth of closure.
• Sea palm and feather boa understory algae occurred mainly at water depths <26 feet (8 meters), with a similar or greater number of records between 15 and 26 feet (5 and 8 meters). Both species had greater cover on reef heights >1 feet (0.3 meter) (Merkel & Associates, Inc. 2025).
• Sea fan occurrence increased with depth, with most records at depths >26 feet (8 meters).

Although sea fans mainly occurred on substrate ≥1 feet (0.3 meters) high, there were more records on reefs <1 feet (0.3 meters) in height than observed for other indicator species, most likely related to less sand influence with increasing depth. • Hard substrate with opportunistic turf algae, sparse occurrence of opportunistic feather boa kelp, and/or lacking vegetation has been used to distinguish substantially sand influenced (scoured) reef.

Sandy Beach Habitat
In addition, beach nourishment would definitely serve to increase the area of sandy beach habitat at this location. It does not include a living shoreline due to the lack of potential to establish one at this site owing to its very narrow beach. Establishing a wider beach provides an opportunity for shorebirds, native vegetation, and intertidal infaunal and fish species that inhabit sandy beaches to utilize the space as an expanded local habitat. It may also provide an opportunity for sensitive species (such as grunion) to expand within their regional distribution range.

As described by CRM (2000), existing sandy beach habitat in the area is “…composed of medium to coarse sand with no rocky intertidal habitat along this part of the shoreline. Typical sandy beach organisms (worms, sand crabs, amphipods, isopods, and clams) exist between the low and high tide marks and will vary on a seasonal basis as a result of changes in physical beach characteristics. All of these species are resilient and have life histories based upon high seasonal turnover.”
Future Possibilities
The definition of success for ecology is that:
• the beach possesses the entire range of sub-habitats (upper intertidal, mid-intertidal, and low intertidal) through-out the year across its widest point, and • the submerged breakwater serves as an attraction for marine organism colonization with the typical local species of mussels, gorgonians, keyhole limpets, urchins, sea cucumbers, Kellet's whelk, sea stars, spotted sand bass, kelp bass, senorita, bat rays, and black perch.

The project would be designed to attract marine growth on the hard-bottom material (stone). The proposed reef is proposed to be constructed out of armor rock, situating it in an ecologically less sensitive area of the seafloor to enhance the habitat potential for subtidal and intertidal species colonization and use. The process is intended to function somewhat similar to the SONGS Wheeler Reef mitigation project reef modules located farther offshore in deeper water off of this site. The breakwater structure could also potentially be enhanced to maximize habitat potential, biodiversity, and species recruitment by installing an outer surface layer composed of biological growth promoting material and of higher surface complexity than armor stone alone (e.g., possibly Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 97 ECOncrete casts or other types of naturalized features, etc.). The City is still actively investigating the feasibility of integrating ECOncrete armor blocks into the structure to provide ecological enhancement to support local species. According to ECOncrete, “The technology helps build up local marine life, supporting the food chain for top predators like seals, and mitigate climate change by storing carbon in calcitic organisms like oysters.” An example successful project is the Living Breakwaters at the Tottenville Shoreline on Staten Island, New Jersey, where armor blocks of ECOncrete were interspersed with eight living breakwaters to protect the shore, provide habitat and public amenities (https://hcr.ny.gov/livingbreakwaters-project-home (New York State 2025). The breakwaters possess thousands of ECOncrete blocks and multiple tide pools enhancing local species supporting the food chain and storing carbon.

The vision would be to mimic conditions of the nearby offshore reef referred to as Seal Rock or San Mateo Rocks. This reef is 2,300 feet offshore and slightly south of the City T Street Beach in water depths of -23 to 28- feet MLLW. Historically, kelp has been prevalent along this section of coastline, but within the last several decades, the canopy has experienced a sharp decline. Other species present in this vicinity that could colonize the breakwater and expand in area include:
mussels, gorgonians, keyhole limpets, urchins, sea cucumbers, Kellet's whelk, sea stars, spotted sand bass, kelp bass, senorita, bat rays, and black perch.

Establishing a wider beach leeward of the structure provides an opportunity for shorebirds, native vegetation, and intertidal benthic infaunal species (sand crabs and bean clams) that inhabit sandy beaches to utilize the space as an expanded local habitat. It may also provide an opportunity for sensitive species (grunion), threatened or endangered species (least terns and snowy plovers), and vegetation species to have more space to expand within their regional distribution range.

3.4.3.9. State Beach Multi-Benefit Emergent Breakwater Concept Summary In summary, the hybrid reef/breakwater structure placed at the southern end of the State Beach is a proposed Phase 1 project concept due to the wide variety of benefits the structure would provide for sand retention, coastal access, recreation and shoreline protection purposes. The placement of the structure in this area would likely directly benefit a wide array of stakeholders due to its location within the City along a State Parks property and where the OCTA railway is significantly threatened by coastal erosion. Recreation and habitat enhancements are also afforded as well.

In summary, the benefits offered by the structure at this location and reasons for its consideration as a project concept are as follows:
• The breakwater/reef will significantly reduce wave energy and resultant erosion impacting the shore at the south end of San Clemente State Beach. It may also benefit the beach adjacent to the southern residential communities which is currently almost completely eroded above the mean high tide line.
• Slowing longshore sediment transport by the structure will allow for the sand accumulation and retention along the shoreline in its lee and immediately up- and downcoast of the structure.
• The prefill of sand behind the structure will establish a revitalized beach for recreation and habitat at the south end of the State beach.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 98 • The sand will offer further protection of the shoreline and coastal infrastructure by buffering wave energy.
• The reef will enhance surf resources in an area where the surfing potential is relatively low. It will be designed to establish high-quality surf breaking both left and right with varying wave types that cater to different skill levels of surfing. • A low wave energy, shallow, sandy wading/swimming zone will be established leeward of the breakwater for beachgoers.
• The surf resources, low energy wading zone, and improved wide, sandy beach will create a draw for tourism and visitation to the beach, which will benefit State Parks as well as the City.
• The sandy beach may help establish a new habitat and foraging area for shorebirds and other species.
• Over time, if the beach becomes wide enough, the back of the beach may be able to be used as a living shoreline with plantings to form a dune-type ecosystem in later phases of the project.
• The rocky reef structure will establish a complex, hard-bottom subtidal and intertidal habitat that will attract a much higher biodiversity and species richness if placed in an area where the habitat quality is relatively low.
• Installing a sand retention feature at the south end of the City could restore lateral coastal access along the beach allowing people to once again walk south to Trestles and San Onofre State Beach.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 99 4. Feasibility Analyses of the Design Concepts
This section of the report presents results of the feasibility assessment of the proposed project concepts. The considerations for determining the feasibility of the project include:
• predicted performance at retaining sand
• costs
• economic benefits
• ability to be permitted
• resilience and adaptability to future sea level rise per the State of California (California Ocean Protection Council, 2024).

4.1. North Beach Multi-Benefit Emergent Breakwater
The first proposed project concept is analyzed for feasibility below.

4.1.1. Predictive Performance at Building and Retaining the Beach Each design concept was analyzed for its ability to retain sand using the method described below and in more detail in Appendix E of this report. Analytical results were also compared to numerical modeling results of the offshore breakwater option for the Oceanside Beach Sand Replenishment and Retention Device Project (GHD 2021) as another reference point.

To estimate the sand retention capabilities of the emergent breakwater concept, empirical methods were used from the Regional Beach Sand Retention Strategy (Moffatt & Nichol and Everts Coastal 2001) that were developed specifically for the Southern California wave climate.

That report analyzed existing and historic structures along the Southern California coastline to form an empirical relationship between sand retention performance and structure design.

The key parameters that affect sand retention potential behind structures include the:
• shore-parallel length of the breakwater.
• breakwater distance offshore of the pre-project shoreline. • wave transmission characteristics of the breakwater.

These parameters specific to the breakwater concept were used as input to this methodology to estimate the salient area that is projected to build up landward of the structure.

The multi-benefit emergent breakwater was analyzed as an offshore breakwater with a crest length of 600 feet located 900 feet offshore of the pre-project shoreline. This crest length is equal to the length of the emerged center portion of the concept. The wave transmission coefficient of the structure was calculated as 0 based on its crest elevation of 10 feet NAVD88 and placement in 15 feet water depth. Based on these values a salient with an alongshore length of 2,580 feet and a maximum cross-shore width of 430 feet was estimated to build up behind the structure. The resulting salient area was estimated to be approximately 13 acres which is roughly equal to between 500,000 and 600,000 cubic yards of sand as shown in Figure 4-1 This is a preliminary estimate which will be modeled in more detail using both numerical models and a physical model during the next phase of the project.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 100
Figure 4-1 shows the predicted salient along the beach behind the structure. The beach extends 1,000 feet into Capistrano Shores to the north and nearly 300 feet south into the revetted reach behind the beach fronting the railroad. This is an extensive beach that may also serve the secondary benefit of trapping sand moving alongshore as it approaches the salient from either direction, depending on the season and its respective direction of longshore sand transport.

This specific project site provides more room along the back of the beach for natural sand dune recruitment or man-made formation of a sustainable living shoreline. Therefore, another benefit of the North Beach site is compatibility between added recreational beach area and a future living shoreline which would function as a sand reservoir for the City.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 101
Figure 4-1: Predicted Sand Retention Performance of the North Beach Multi-Benefit Emergent Breakwater Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 102

4.1.2. Costs
Table 4-1 below shows the overall costs of the project including preliminary engineering, environmental review, permitting, design, and construction.

The total opinion of probable construction costs is $89.0 Million. The hard costs of actual construction are $66.6 Million without contingency, while monitoring costs are estimated to be roughly $585,000. The contingency is 25% of the hard costs at this stage or $16.8 Million. Soft costs of planning, engineering, environmental review, permitting, construction management, support, surveying, inspection and administration are roughly $5.0 Million.

A significant portion of that is the beach nourishment component at $32.0 Million. The cost for sand is high because it is assumed to be sourced from Surfside/Sunset Beach at $41.63 per cubic yard (the price in a competitive situation) due to the long distance from source to destination. Also, it is assumed that the dredge used will be mobilized from the west coast of the U.S. as the project could be timed to occur when a hopper dredge is in the region, so the mobilization cost is relatively low compared to mobilizing through the Panama Canal from the east coast.

The City conducted an offshore borrow site investigation to find closer sources of beach quality sand that was expanded with participation of the OCTA, and the results are expected after submittal of this report. If local sand can be sourced from closer to the site, then that would decrease and subsequently reduce the soft costs that are percentages of the construction cost.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 103
Table 4-1: Conceptual Level Implementation Costs for the North Beach Multi-Benefit Emergent Breakwater
Item
No. Item Description Quantity Unit Unit Cost Subtotal
Beach Nourishment Components
1 Mobilization & Demobilization of
Earthmoving Equipment
1 LS. $25,000.00 $25,000
2 Mobilization & Demobilization of Dredging
Equipment
1 L.S. $5,000,000.00 $5,000,000
3 Temporary Protective Construction Fence 2,600 LF $3.00 $7,800 4 Offshore Dredging off Surfside/Sunset
Beach & Transport
566,280 CY $41.63 $23,574,236
5 Nourishment at the Beach Behind the
Breakwater
566,280 CY $6.00 $3,397,680
Subtotal Beach Nourishment $32,004,716
Offshore Breakwater Components
6 Mob/Demob/Prep Work 1 LS. $500,000.00 $500,000
7 Armor Layer 122,000 Tons $110.00 $13,420,000
8 Underlayer 240,350 Tons $86.00 $20,670,100
Subtotal Offshore Breakwater $34,590,100
Monitoring and Maintenance
9 Pre-Construction – Beach Profiles, Grunion 1 LS $50,000.00 $50,000 10 Construction – Grunion, Water Quality 1 LS $35,000.00 $35,000 11 Post-Construction - Beach Profiles, Surfing 5 YRS $100,000.00 $500,000 Subtotal Monitoring $585,000
Subtotal Items $67,179,816
Contingency of 25% $16,794,954
Planning, Environmental Review,
Permitting, Design (2.5%)
1 EA 0.0250 $2,099,369
Construction Support Services (1.%) 1 EA 0.0100 $839,748 Construction Management (1.5%) 1 EA 0.0150 $1,259,622
Inspection, Survey, and Administration
(1%)
1 EA 0.0100 $839,748
Grand Total $89,013,257
ASSUMPTIONS:
1 Dredge mobilization cost assumes the hopper dredge is on the west coast and does not come from the east coast.
2 Sand is sourced from the Surfside/Sunset Beach borrow site; sand from a closer source would reduce unit costs.
3 A living shoreline is not yet included in the project. 4 The sand volume assumed for the estimate is the high end of the range expressed in the concept design report.
5 Breakwater component quantities are based on AutoCadd design.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 104
Construction of the project would entail building the reef first and then adding the sand salient deposit second. The sand salient will be installed as beach nourishment behind the structure to prevent trapping of sand moving alongshore after the reef is installed. That effect would capture up to 500,000 to 600,000 cubic yards of sand over time. To ensure downcoast and upcoast impacts are avoided, a pre-fill salient will be installed to prevent sand capture from littoral drift.

Natural longshore sand transport will continue around and over the salient once it is established and thus maintain sand delivery along the northern City coast.

4.1.3. Economic Benefits
Benefit-Cost Analysis (BCA) is a systematic approach for evaluating the economic value of different policy or project options by comparing their expected costs and benefits. For hazard mitigation projects, the BCA determines the future risk-reduction benefits of a project and weighs those benefits against project costs (Federal Emergency Management Administration [FEMA] 2024).

The BCA of each project was prepared by the firm CETO and is included in this section for North Beach and is presented for each project in their respective sections. See Appendix E for the full preliminary economic report. The economics analyses attached are an initial preliminary evaluation. This evaluation is different than the federal government agency methodology for determining costs and benefits.

As background, the application of BCA in a recreation or hazard mitigation analysis often involves valuing non-market goods, such as clean air, water quality, the value of a day at the beach, and biodiversity, which are typically not traded in markets but provide substantial benefits to society.

These resources provide significant benefits to individuals and to society; however, because they do not have explicit market prices, their value is often overlooked. Non-market valuation (NMV) methods are essential for capturing the true economic value of these resources, which is crucial for informed policymaking and resource management.

The analysis in this study combines aspects of the various federal agencies' methodologies with empirical research and established practice specific to California to provide the most accurate estimate of the value of beach replenishment under the Nature-Based Adaptation Project Feasibility Study.

Replenishment of North Beach yields the greatest benefits of any beach in the economic model in terms of avoided lost recreational value. Daily data is not collected for North Beach, and therefore annual estimates were converted to daily estimates using a method developed for San Diego County and considered representative of south Orange County conditions.

The high losses in recreation value result from North Beach’s high relative annual attendance and narrow remaining width of the beach in 2024 (approximately 109 feet). Without replenishment, North Beach will disappear completely in 2046, with cumulative NMV losses reaching about $203 million by 2050, as shown in Figure 4-2 below.

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Figure 4-2: Expected NMV Loss Due to Coastal Erosion With and Without Replenishment at North Beach $-
$50,000,000
$100,000,000
$150,000,000
$200,000,000
$250,000,000
-
50,000
100,000
150,000
200,000
250,000
Cumulative $ Losses
# of persons
Year
North Beach, Lost Capacity and Cumulative NMV Losses
Unreplenished and Replenished
# of people over capacity Replenished # of people over capacity Cumulative Lost NMV Replenished Cumulative Lost NMV Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 106
North Beach sees a significant NMV benefit from replenishment. The cumulative value of replenishment is about $203 Million undiscounted ($129 Million with a 3 percent discount rate).

Please note that these are only for recreational benefits. If one includes other benefits, the total benefits will be higher, possible by a significant amount given the value of the rail line.

4.1.4. Regulatory Processes
The Project can be permitted given sufficient time and resources. This Project will require permits or determinations from several resource agencies and the anticipated permits for a multi-purpose reef and beach nourishment project are summarized in Table 4-2. Projects would also have to meet requirements of both CEQA and NEPA
It will be important to get buy-in early on from permitting agencies. This can take the form of targeted meetings with individuals who are anticipated to play an important role later in the process. The approach in such meetings would begin with a sound vision from the City and anticipating common concerns of each agency.

Additionally, a partnership with SANDAG, OC Parks, and the OCTA may enhance the ability to secure the necessary permits, as such agencies have a track record of shoreline projects and influence within the region.

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Table 4-2: North Beach Multi-Benefit Emergent Breakwater Permitting Actions Resource Agency Permit/Approval
Federal
U.S. Army Corps of Engineers (USACE) • Permit under Section 404 of the Clean Water Act, 33 USC Section 1344 • Section 10 of the River and Harbors Act of 1899, 33 USC Section 403 State
Regional Water Quality Control Board (RWQCB) • Water Quality Certification under Section 401 of the Clean Water Act California Coastal Commission (CCC) • Coastal Development Permit (CDP) California State Lands Commission (SLC) • Lease of State Lands Regional/Local
City of San Clemente • Encroachment and Grading Permits • Noise Variance or Exemption Letter
County of Orange, Department of Public Works • Encroachment and Grading Permits for work in Reach 1 • Noise Variance or Exemption Letter
SCRRA/Metrolink • ROW Permit
A similar project is in its planning process in the City of Oceanside for the Re:Beach concept. The City is moving that project forward in design and analyses which places it ahead of North Beach in the process and can serve as an opportunity for lessons learned. The North Beach project is similar to the Oceanside sand retention project and can therefore benefit from work done to gain approvals for Re:Beach. San Clemente and Oceanside should continue to coordinate closely.

The agencies may require the project to be implemented as a pilot project that proposes full removal if the project fails to perform. The City will likely need to develop an adaptive management plan to address future conditions. Detailed monitoring will likely be required to prove the project performed successfully and as intended. The intended purpose of including sand a pilot retention measure is to reduce the need for renourishment over time and therefore reduce future disturbance and costs.

The public will need to continue to be involved with project progress and have input along the way. The local stakeholders have shown support for the project thus far. It will be important for the City to be able to continue to garner public support at every step to maintain a sufficient level of public support to implement it. The issues that may raise public questions may be related to views, safety, costs, and other potential concerns. Keeping these issues at the forefront of planning and analyses during the project design and reporting will help maintain/secure a supportive position of the public.

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4.1.5. Sea Level Rise Resilience/Adaptability
The project would improve resilience SLR through protection of North Beach from direct wave attack and restoration of a stable dry beach to mitigate increased erosion and storm damage. It will directly benefit the City’s north end during sea level rise by holding a beach in position while widening and elevating that beach over time. However, its function may diminish over time if sea levels rise above certain amounts which are still to be determined.

The City completed a SLRVA in 2019 and evaluated three scenarios into the future for vulnerability and adaptation. The State updated the SLR guidelines in 2024 indicating that future sea level rise may vary from prior projections (California Ocean Protection Council 2024). Table 4-3 shows the original 2018 SLR scenarios evaluated by the City and the recent 2024 scenarios evaluated by the City for this NBFS. The City evaluates three new scenarios based on the latest 2024 guidance that are similar and comparable to the prior scenarios.

Table 4-3: Sea Level Rise Projections Evaluated for the City SLRVA and the NBFS City SLR Scenarios Evaluated in 2019 Based on
2018 State Guidance (OPC)
City SLR Scenarios Evaluated in 2025 Based on
2024 Revised State Guidance (OPC)
Intermediate-High Scenario
Projection (Feet) Year(s) Projection (Feet) Year

0.8 2030-2040 1.6 2060

3.3 2060-2100 3.1 2080

4.9 2070-2130 4.8 2100
Note: All projections are based on data from the La Jolla Tide Gage.

The performance of this project is analyzed for its sand retaining performance during rising sea levels over time. The estimated area of the sand salient formed behind the structure is shown below in Table 4-4 for each SLR scenario referred to above.

Table 4-4: North Beach Multi-Benefit Emergent Breakwater SLR Timeframe (Approximate Year) Sea Level Rise Scenario (Feet) Salient Surface Area (Acres) 2025 0.0 13.0
2060 1.6 8.0
2080 3.1 5.8
2100 4.8 3.0
The projections show that the surface area of the sand salient will decrease as sea levels rise.

Detailed project analyses will be conducted during the subsequent engineering phase of the project to better quantify evolution of the beach over time. However, the general trend is estimated here to show the magnitude of change, and to identify adaptative management actions that can be considered to offset the effects of SLR.

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Resilience and adaptability to SLR is the ability for the project to continue its successful function over time as ocean water levels rise. SLR results in high average water levels over time, and higher coastal storm water conditions. Higher water levels result in two types of effects, including 1) the breakwater becomes less effective at blocking waves as waves are more able to overtop the structure, and 2) greater wave forces on the breakwater that may cause damage to it and require repair; lack of repair once the breakwater is damaged could lead to less effectiveness of the wave blocking function of the structure and further decreased function. Each effect is described below.

Decreased Wave Blocking Capability of the Breakwater During Sea Level Rise Ocean waves will be more able to pass over the breakwater at high tide as water levels rise with SLR. However, this breakwater crest is conceived at +10 feet NAVD and presently clears the highest high tide (+7.6 feet) by at least 2.4 feet. Sea level would have to rise above the 2.4 feet of freeboard presented by the breakwater at the highest high tide to increase any wave transmission over the structure. Therefore, the SLR scenarios of +3.1 feet and +4.8 feet would provide conditions that would allow wave energy over the structure at high tide.

SLR of +3.1 feet would exceed the freeboard by 0.7 feet at the highest high tide and allow some relatively limited amount of wave energy over the structure. The amount of energy would be relatively low as waves passing over the structure would completely break, and their energy would be significantly dissipated before reaching the beach.

SLR of 4.8 feet would exceed the breakwater crest elevation by 2.4 feet thus allowing increased wave energy over the structure. Again, the amount of energy overtopping the structure would be decreased because the waves would break on the structure and their energy would dissipate.

Both of these scenarios would convey waves over the structure only at the highest high tides of the year which occur infrequently, so the frequency of this occurrence would be rare. During the majority of the time the breakwater would still effectively block waves. Also, the combined probability of having high waves occur simultaneously with the highest possible tides of the year at those timeframes is even lower.

It is acknowledged that the breakwater function may decrease over time, but that decrease is modest and not a constant condition, but rather an episodic condition occurring only during extreme events. The long-term function of the structure should remain effective over time.

Adaptive actions that can be taken to preserve the function of the breakwater to block waves would be to raise the crest elevation the same amount as sea level rise to compensate for its effects and possibly add more sand to the salient. Increasing the crest elevation can be done by adding rock on the crest using similar equipment as that which built the structure originally. The revetment base may need to be designed to be wider than needed initially to accommodate the addition of rock on the crest and slopes at a later date for adaptation.

Greater Wave Forces on the Breakwater That May Cause Damage and Require Repair Sea level rise will result in deeper water at the breakwater toe location over time which enables higher waves to break on the structure. Higher waves impart higher levels of energy on the breakwater, thus increasing the stresses on the rock structure more over time. This may increase wear and damage to the breakwater over time thus triggering damage, increased maintenance and/or resulting in decreased function.

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The breakwater is conceived to be capable of withstanding significant storm conditions (e.g., the 100-year coastal storm wave condition) for present-day ocean water levels but will need to be designed to be high enough and of sufficient stone size to also function during future conditions.

The crest elevation and rock size will need to be tested with numerical and physical models to confirm its performance under existing conditions, and how far into the future it can sustain function. The team will need to work with City staff to determine the desired future condition for the reef’s performance.

The City of Oceanside reef project considered how their alternative could be adapted to perform under future SLR scenarios up to 2 feet. The City may wish to consider this option and then decide how far into the future their reef needs to function. The reef can also be augmented by being raised with adding larger stones along the crest over time, which would enlarge the footprint. This action is entirely feasible and would render the reef able to function under higher water levels and higher wave conditions in the future. However, it will add costs to the project in future as maintenance, repair, and improvement.

In addition, sand may need to be added to the salient overtime to keep up with SLR. The beach will naturally rise in elevation as water levels rise, but eventually the water level may rise high enough to squeeze the beach area into a such a narrow band as to be less effective at protecting the backshore. In that instance the City may need to add sand to the salient to provide sufficient distance of waves from infrastructure on the beach.

The Oceanside study (GHD 2021) identified that multi-purpose reefs were scored highest in adaptability because they also provide increased wave energy dissipation in the alongshore direction.

4.2. Capistrano Shores Submerged Breakwater and “Speed Bumps” This second proposed project concept is analyzed for feasibility below and is shown in Figure 4-3.

4.2.1. Predictive Performance at Building Beaches
The same empirical methods (Moffatt & Nichol and Everts Coastal 2001) used for the emergent breakwater concept were employed to estimate the sand retention capabilities of the Capistrano Shores submerged breakwater concept. As stated in the section above, analysis results were compared to numerical modeling results of the offshore breakwater option for the Oceanside Beach Sand Replenishment and Retention Device Project (GHD 2021) for reality.

The submerged breakwater concept was modeled as a 2,000 feet long breakwater located 1,500 feet offshore of the pre-project shoreline. The wave transmission coefficient of the structure was calculated as 0.4 based on its crest elevation of 0 feet NAVD88 and placement in 20 feet of water depth. Based on these values a salient with an alongshore length of 2,700 feet and a maximum cross-shore width of 450 feet was estimated to build up behind the structure.

The area of the salient was estimated to be approximately 14 acres as explained in Appendix D.

That would require pre-fill nourishment of between 600,000 and 700,000 cubic yards of sand.

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The ”speed bumps” are included in this alternative to encourage added sand deposition at the boundaries of the project. They are relatively small interruptions to sand transport alongshore and should serve to slightly slow its movement into and out of the shadow zone behind the breakwater.

In this way sand movement should slow down enough for sand to deposit at the beach for a more prolonged period of time before being remobilized and moved farther alongshore and out of the energy shadow. These features are included in this alternative because it proposes a submerged breakwater which is slightly less effective than an emergent breakwater in creating an energy shadow area. These features also included in this alternative because the beach is private, which will result in their footprints not occupying the public beach, but rather occupy private beach area.

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Figure 4-3: Anticipated Salient Dimensions for the Submerged Breakwater Concept at Capistrano Shores Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 113

4.2.2. Costs
Table 4-5 below shows the overall costs of the project. The costs include those for planning, design, and construction. The total opinion of probable construction costs is $60.3 Million. The hard costs of actual construction are $45.0 Million without contingency, while monitoring costs are estimated to be roughly $585,000. The contingency is 25% of the hard costs at this stage or $11.4 Million. Soft costs of planning, engineering, environmental review, permitting, construction management, support, surveying, inspection and administration are roughly $3.4 Million.

A significant portion of that is the beach nourishment component at $34.0 Million. The cost for sand is high because it is assumed to be sourced from Surfside/Sunset Beach at $41.63 per cubic yard, assuming a competitive bidding situation, due to the long distance from source to destination. If local sand can be sourced from closer to the site, then that would decrease and subsequently reduce the soft costs that are percentages of the construction cost.

As with the North Beach project, construction of the project would entail building the reef first and then adding the sand salient deposit second. The sand salient will be installed as beach nourishment behind the structure to prevent trapping of sand moving alongshore after the reef is installed. That effect would capture up to 600,000 to 700,000 cubic yards of sand over time from adjacent beaches that are already denuded anyway, thus adding to the erosion problem nearby.

A pre-fill salient will be installed to prevent any sand capture from the City beaches. Natural longshore sand transport will continue around and over the salient once it is established and thus maintain sand delivery along the northern City coast.

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Table 4-5: Conceptual Level Implementation Costs for the Capistrano Shores Submerged Breakwater
Item
No. Item Description Quantity Unit Unit Cost Subtotal
Beach Nourishment Components
1 Mobilization & Demobilization of
Earthmoving Equipment
1 LS $25,000.00 $25,000
2 Mobilization & Demobilization of Dredging
Equipment
1 LS $5,000,000.00 $5,000,000
3 Temporary Protective Construction Fence 2,700 LF $3.00 $8,100 4 Offshore Dredging off Surfside/Sunset
Beach & Transport
609,840 CY $41.63 $25,387,639
5 Nourishment at the Beach 609,840 CY $6.00 $3,659,040
Subtotal Beach Nourishment $34,079,779
Offshore Breakwater Components
6 Mob/Demob/Prep Work 1 LS $500,000.00 $500,000
7 Armor Layer 80,640 Tons $110.00 $8,870,400
8 Underlayer 11,700 Tons $86.00 $1,006,200
9 Speed Bumps 2 EA $250,000.00 $500,000
Subtotal Offshore Breakwater $10,876,600
Monitoring and Maintenance
10 Pre-Construction – Beach Profiles, Grunion 1 LS $50,000 $50,000 11 Construction – Grunion, Water Quality 1 LS $35,000 $35,000 12 Post-Construction – Beach Profiles, Dune
Plants, Weeding
5 YRS $500,000 $500,000
Subtotal Monitoring $585,000 $585,000
Subtotal Items $45,541,379
Contingency of 25% $11,385,345
Planning, Environmental Review, Permitting,
Design (2.5%)
1 EA 0.0250 $11,385,345
Construction Support Services (1.%) 1 EA 0.0100 $11,385,345 Construction Management (1.5%) 1 EA 0.0150 $11,385,345
Inspection, Survey, and Administration (1%) 1 EA 0.0100 $11,385,345 Grand Total $60,342,327

ASSUMPTIONS
1 Dredge mobilization cost assumes the hopper dredge is on the west coast and does not come from the east coast.
2 Sand is sourced from the Surfside/Sunset Beach borrow site; sand from a closer source would reduce unit costs.
3 A living shoreline is not yet included in the project.

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4 The sand volume assumed for the estimate is the high end of the range expressed in the concept design report.
5 Breakwater component quantities are based on AutoCadd design.

4.2.3. Economic Benefits
As mentioned in the discussion for the previous alternative, a BCA was performed to determine the project’s economic improvements of existing conditions. The BCA of each project was prepared by the firm CETO and is included in this section for Capistrano Shores. See Appendix F for the full economic report. The economics analyses attached are different than the federal government agency methodology for determining costs and benefits.

Replenishment of Capistrano Shores would produce millions in recreational value. Capistrano Shores already experiences NVM losses due to erosion and overcrowding, as Capistrano Shores is already almost completely eroded with just 15 feet of sand remaining. The model of the impacts of erosion and replenishment for Capistrano Shores uses an erosion rate of 0.6 feet/year. Daily attendance data was not available for Capistrano Shores; therefore, the method developed in San Diego County was used for south Orange County due to their similarities to calculate that number.

The high losses in recreational value primarily result from its narrow initial width. Capistrano Shores expected capacity was exceeded by almost 15,000 in 2024. This number only grows to about 75,000 by 2029, which is when the beach will become entirely depleted in this no-action scenario. Therefore, while erosion is relatively low, the pre-existing narrow beach results in total NMV losses of about $115 Million by 2050 if no action is taken, as can be seen in Figure 4-4 below. Capistrano Shores also sees a significant NMV benefit from replenishment. The cumulative value of replenishment is about $114 Million undiscounted ($79 Million with a 3% discount rate). Please note that these are only for recreational benefits. If one includes other benefits, the total benefits will be higher.

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Figure 4-4: Expected NMV Loss Due to Coastal Erosion With and Without Replenishment at Capistrano Shores $-
$20,000,000
$40,000,000
$60,000,000
$80,000,000
$100,000,000
$120,000,000
-
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
Cumulative $ Losses
# of persons
Year
Capistrano Shores, Lost Capacity and Cumulative NMV Losses Unreplenished and Replenished
# of people over capacity Replenished # of people over capacity Cumulative Lost NMV Replenished Cumulative Lost NMV Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 117

4.2.4. Regulatory Processes
As with the North Beach project, the Capistrano Shores Submerged Reef Project can be permitted given sufficient time and resources. The difference between this project and the North Beach project is that it is along a private beach and private property. This may trigger more onerous permitting requirements by the agencies. Our experience shows that project applicants that are public agencies may be given certain considerations that private property owner applicants may not receive. Therefore, the Capistrano Shores Community may be required to do more work to get their permits and have to agree to more monitoring and reporting afterward.

This Project will require permits from several resource agencies as summarized in below.

Table 4-5 in the prior section of this report shows permitting consisting of the those from the USACE, RWQCB, CCC, SLC, the City and potentially the County. Projects will always have to meet requirements of both CEQA and NEPA.

As expressed above, early discussions with the permitting and resource agencies are important to success. Also, any partnerships will be important to securing permits such as with the City and any other groups that can be added such as SANDAG, OC Parks and the OCTA.

The similar challenge of breaking new ground will trigger studies and proof of concept to an extent beyond a typical nourishment project. The Oceanside Re:Beach project will help with initiating agency consideration of this type of concept. Coordination between the homeowners and the Cities of San Clemente and Oceanside should occur from the outset.

The agencies may require the project to be implemented as a pilot project that proposes full removal if the project fails to perform. The homeowners may need to develop a contingency plan for such an event and hold funding aside or obtain insurance for removal if that were determined to be necessary. Detailed monitoring will be required to prove the project performed successfully.

The public will need to support the project for success. Issues that may include views (although it is only visible at a very low tide), safety, costs, navigation hazards, and other potential concerns.

Proactively addressing these will lead to a higher probability of success.

4.2.5. Sea Level Rise Resilience/Adaptability
The project would improve resilience to SLR through protection of Capistrano Shores from direct wave attack and restoration of a stable dry beach to mitigate increased erosion and storm damage. It will directly benefit the City’s north end during sea level rise by holding a beach in position while widening and elevating that beach over time. However, its function may diminish over time if sea levels rise above certain amounts which are still to be determined.

The City completed a SLRVA in 2019 and evaluated three scenarios into the future for vulnerability and adaptation. The State updated the SLR guidelines in 2024 indicating that future sea level rise may vary from prior projections. Table 4-6 shows the original 2018 SLR scenarios evaluated by the City and the recent 2024 scenarios evaluated by the City for this NBFS. The City evaluates three new scenarios based on the latest 2024 guidance that are similar and comparable to the prior scenarios.

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Table 4-6: Sea Level Rise Projections Evaluated for the City SLRVA and the NBFS City SLR Scenarios Evaluated in 2019 Based on
2018 State Guidance (OPC)
City SLR Scenarios Evaluated in 2025 Based on
2024 Revised State Guidance (OPC)
Intermediate-High Scenario
Projection (Feet) Year(s) Projection (Feet) Year

0.8 2030-2040 1.6 2060

3.3 2060-2100 3.1 2080

4.9 2070-2130 4.8 2100
Note: All projections are based on data from the La Jolla Tide Gage.

The performance of this project is analyzed for its sand retaining performance during rising sea levels over time. The estimated area of the sand salient formed behind the structure is shown below in Table 4-7 for each SLR scenario referred to above.

Table 4-7: Capistrano Shores Multi-Benefit Submerged Breakwater and “Speed Bumps” SLR Timeframe (Approximate Year) Sea Level Rise Scenario (Feet) Salient Surface Area (Acres) 2025 0.0 14.0
2060 1.6 4.5
2080 3.1 2.2
2100 4.8 0.8
The projections show that the surface area of the sand salient will decrease as sea levels rise.

Detailed project analyses will be conducted during the subsequent engineering phase of the project to better quantify evolution of the beach over time. However, the general trend is estimated here to show the magnitude of change, and to identify adaptative management actions that can be considered to offset the effects of SLR.

Resilience and adaptability to SLR is the ability for the project to continue its successful function over time as ocean water levels rise. SLR results in high average water levels over time, and higher coastal storm water conditions. Higher water levels result in two types of effects, including 1) the submerged breakwater crest becomes deeper below water and less effective at blocking waves as waves are more able to pass over the structure less impeded, and 2) greater wave forces are imparted on the breakwater that may cause damage to it and require repair; lack of repair once the breakwater is damaged could lead to less effectiveness of the wave blocking function of the structure and further decreased function. Each effect is described below.

Decreased Wave Attenuation Capability of the Breakwater During Sea Level Rise Ocean waves will be more able to pass over the breakwater unimpeded at lower, mid-, and high tides as water levels rise with SLR. This submerged breakwater crest is conceived at +0 feet NAVD and would be below the highest high tide by +7.6 feet. Sea level would always be above the breakwater at mid and high tides thus allowing wave transmission over the structure.

Therefore, the SLR scenarios of +3.1 feet and +4.8 feet would simply increase the depth of the breakwater crest and render it less effective at intercepting wave energy.

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SLR of +3.1 feet would exceed the crest elevation by 10.7 feet at the highest high tide and allow more wave energy over the structure than in present conditions. The amount of energy would be increased above that immediately after construction and more energy would be able to reach the beach, thus dispersing sand and reducing the area of the beach.

SLR of 4.8 feet would exceed the breakwater crest elevation by 12.4 feet at the highest high tide and allow even more wave energy over the structure than in present conditions. The amount of energy would be further increased above that immediately after construction and more energy would be able to reach the beach, thus dispersing sand more widely and reducing the area of the beach.

The breakwater function will decrease over time and adaptive actions would need to be taken to preserve the function of the breakwater to partially block waves would be to raise the crest elevation the same amount as sea level rise to compensate for its effects, and add more sand to the salient. Increasing the crest elevation can be done by adding rock on the crest using similar equipment as that which built the structure originally. The revetment base will need to be designed to be wider than needed initially to accommodate the addition of rock on the crest and slopes at a later date for adaptation.

Greater Wave Forces on the Breakwater That May Cause Damage and Require Repair Sea level rise will result in deeper water at the breakwater toe location over time which enables higher waves to break on the structure. Higher waves impart higher levels of energy on the breakwater, thus increasing the stresses on the rock structure more over time. This may increase wear and damage to the breakwater over time thus triggering damage, increased maintenance and/or resulting in decreased function.

The breakwater is conceived to be capable of withstanding significant storm conditions (e.g., the 100-year coastal storm wave condition) for present-day ocean water levels but will need to be designed to be high enough and of sufficient stone size to also function during future conditions.

The crest elevation and rock size will need to be tested with numerical and physical models to confirm its performance under existing conditions, and how far into the future it can sustain function. The team will need to work with City staff to determine the desired future condition for the reef’s performance.

The City of Oceanside reef project considered how their alternative could be adapted to perform under future SLR scenarios up to 2 feet. The City may wish to consider this option and then decide how far into the future their reef needs to function. The reef can also be augmented by being raised with adding larger stones along the crest over time, which would enlarge the footprint. This action is entirely feasible and would render the reef able to function under higher water levels and higher wave conditions in the future. However, it will add costs to the project in future as maintenance, repair, and improvement.

In addition, sand will need to be added to the salient overtime to keep up with sea level rise. The beach will naturally rise in elevation as water levels rise, but eventually the water level may rise high enough to squeeze the beach area into a such a narrow band as to be less effective at protecting the backshore. In that instance the City may need to add sand to the salient to provide sufficient distance of waves from infrastructure on the beach.

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4.3. State Beach Multi-Benefit Emergent Breakwater
The analysis for the State Beach Multi Benefit Emergent Breakwater is nearly identical to that for the North Beach concept and it does not need to be repeated; an abbreviated version of it is provided below.

The main differences between the North Beach and State Beach project concepts are that 1) the State Beach reef is located closer to shore, and 2) that this State Beach Reef is partially fronting private property so the agencies may react differently to a permit application that has benefits for both public and private property.

4.3.1. Predictive Performance at Building Beaches
The multi-benefit emergent breakwater concept located at San Clemente State Beach is the same design as the concept at North Beach. The dimensions of the concept are the same and it is also designed to be located in 15 feet of water depth. The existing beach slope at State Beach, however, is slightly steeper than North Beach resulting in the concept being located closer to the pre-project shoreline.

The State Beach concept is located 600 feet offshore as opposed to 900 feet at North Beach.

This affects the salient calculations and results in a salient with an alongshore length of 2,520 feet, a maximum cross-shore width of 420 feet, and an area of approximately up to 12 acres as seen in Figure 4-5 that would require pre-filling with between 600,000 and 600,000 cubic yards of sand. This is a preliminary estimate which will be modeled in more detail during the following phases of the project.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 121
Figure 4-5: Anticipated Salient Dimensions for the Multi-Benefit Emergent Breakwater at San Clemente State Beach Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 122

4.3.2. Costs
Table 4-1 in Section 4.1.2 of this document shows the overall costs of the State Beach project.

The costs for this concept are identical to the costs for the North Beach project, and include those for planning, design, and construction. The total opinion of probable construction costs is $89.0 Million. The hard costs of actual construction are $66.0 Million without contingency, while monitoring costs are estimated to be roughly $585,000. The contingency is 25% of the hard costs at this stage or $16.8 Million. Soft costs of planning, engineering, environmental review, permitting, construction management, support, surveying, inspection and administration are roughly $5.0 Million.

A significant portion of that is the beach nourishment component at $45.5 Million. The cost for sand is high because it is assumed to be sourced from Surfside/Sunset Beach at $41.63 per cubic yard, assuming competitive bidding conditions, due to the long distance from source to destination. If local sand can be sourced from closer to the site, then that would decrease and subsequently reduce the soft costs that are percentages of the construction cost.

As with the North Beach project, construction of the project would entail building the reef first and then adding the sand salient deposit second. The sand salient will be installed as beach nourishment behind the structure to prevent trapping of sand moving alongshore after the reef is installed. That effect would capture up to 500,000 to 600,000 cubic yards of sand over time from adjacent beaches that are already denuded anyway, thus adding to the erosion problem nearby.

A pre-fill salient will be installed to prevent any sand capture from San Clemente beaches. Natural longshore sand transport will continue around and over the salient once it is established and thus maintain sand delivery along the northern San Clemente coast.

4.3.3. Economic Benefits
As mentioned in the discussion for the previous alternatives, a Benefit to Cost Analysis (BCA) was performed to determine the project’s economic improvements of existing conditions. The BCA of each project was prepared by the firm CETO and is included in this section for the State Beach. See Appendix F for the full economic report. The economics analyses are different than the federal government agency methodology for determining costs and benefits.

Due to the relatively lower attendance rates of the State Beach, replenishment has some recreational benefits, but they are lower than the other two beaches in this project. While historical data suggests that this beach would see erosion, currently the State Beach has a sandy beach.

With this initial limited beach width, even low attendance can add up to positive revenue numbers.

Without action, NMV losses through 2050 will total more than $160 Million, as shown in Figure 4-6.

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Figure 4-6: Expected NMV Loss Due to Coastal Erosion With and Without Replenishment at State Beach $-
$20,000,000
$40,000,000
$60,000,000
$80,000,000
$100,000,000
$120,000,000
$140,000,000
$160,000,000
$180,000,000
-
20,000
40,000
60,000
80,000
100,000
120,000
202420252026202720282029203020312032203320342035203620372038203920402041204220432044204520462047204820492050 Cumulative $ Losses
# of persons
Year
State Beach, Lost Capacity and Cumulative NMV Losses
Unreplenished and Replenished
# of people over capacity Replenished # of people over capacity Cumulative Lost NMV Replenished Cumulative Lost NMV
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With replenishment but without accounting for the protective benefits of the breakwater, overcrowding is alleviated until 2038. In this worst-case scenario, the benefit of this replenishment through 2050 to replenishing State Beach is $160 Million. Please note that these are only for recreational benefits. If one includes other benefits, the total benefits will be higher, possible by a significant amount given the value of the rail line.

4.3.4. Regulatory Processes
As with the North Beach project, the State Beach Multi-Purpose Reef Project can be permitted given sufficient time and resources. The difference between this project and the North Beach project is that a portion of it is along a private beach and private property. This may trigger more onerous permitting requirements by the agencies. Experience shows that project applicants that are public agencies may be given certain considerations that private property owner applicants may not receive. Therefore, the applicant(s) may be required to do more work to get their permits and have to agree to more monitoring and reporting afterward. This Project will require permits from several resource agencies as summarized in Table 4-2 in the prior section of this report, consisting of the USACE, RWQCB, CCC, SLC, the City and potentially the County. Projects will always have to meet requirements of both CEQA and NEPA.

As expressed above, early discussions with the permitting and resource agencies are important to success. Also, any partnerships will be important to securing permits such as with the City and any other groups that can be added such as State Parks, SANDAG, OC Parks and the OCTA.

The similar challenge of breaking new ground will trigger studies and proof of concept to an extent beyond a typical nourishment project. The Oceanside Re:Beach project will help with initiating agency yards consideration of this type of concept. Coordination between the homeowners and the Cities of San Clemente and Oceanside should occur from the outset.

The agencies may require the project to be implemented as a pilot project that proposes full removal if the project fails to perform. The homeowners may need to develop a contingency yards plan for such an event and hold funding aside or obtain insurance for removal if that were determined to be necessary. Detailed monitoring will be required to prove the project performed successfully.

The public will need to support the project for success. Issues that may include views, safety, costs, navigation hazards, surfing effects, and other potential concerns. Proactively addressing these will lead to a higher probability of success.

4.3.5. Sea Level Rise Resilience/Adaptability
The project would improve resilience to SLR through protection of the State Beach from direct wave attack and restoration of a stable dry beach to mitigate increased erosion and storm damage. It will directly benefit the City’s south end during sea level rise by holding a beach in position while widening and elevating that beach over time. However, its function may diminish over time if sea levels rise above certain amounts which are still to be determined.

The City completed a SLR VA in 2019 and evaluated three scenarios into the future for vulnerability and adaptation. The State updated the SLR guidelines in 2024 indicating that future sea level rise may vary from prior projections. Table 4-8 shows the original 2018 SLR scenarios evaluated by the City and the recent 2024 scenarios evaluated by the City for this NBFS. The City evaluates three new scenarios based on the latest 2024 guidance that are similar and comparable to the prior scenarios.

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Table 4-8: Sea Level Rise Projections Evaluated for the City SLRVA and the NBFS City SLR Scenarios Evaluated in 2019 Based on
2018 State Guidance (OPC)
City SLR Scenarios Evaluated in 2025 Based on
2024 Revised State Guidance (OPC)
Intermediate-High Scenario
Projection (Feet) Year(s) Projection (Feet) Year

0.8 2030-2040 1.6 2060

3.3 2060-2100 3.1 2080

4.9 2070-2130 4.8 2100
Note: All projections are based on data from the La Jolla Tide Gage.

The performance of this project is analyzed for its sand retaining performance during rising sea levels over time. The estimated area of the sand salient formed behind the structure is shown below in Table 4-9 for each SLR scenario referred to above.

Table 4-9: State Beach Multi-Benefit Emergent Breakwater SLR Timeframe (Approximate Year) Sea Level Rise Scenario (Feet) Salient Surface Area (Acres) 2025 0.0 12.0
2060 1.6 7.7
2080 3.1 5.4
2100 4.8 2.8
The projections show that the surface area of the sand salient will decrease as sea levels rise.

Detailed project analyses will be conducted during the subsequent engineering phase of the project to better quantify evolution of the beach over time. However, the general trend is estimated here to show the magnitude of change, and to identify adaptative management actions that can be considered to offset the effects of SLR.

Resilience and adaptability to SLR is the ability for the project to continue its successful function over time as ocean water levels rise. SLR results in high average water levels over time, and higher coastal storm water conditions. Higher water levels result in two types of effects, including 1) the breakwater becomes less effective at blocking waves as waves are more able to overtop the structure, and 2) greater wave forces on the breakwater that may cause damage to it and require repair; lack of repair once the breakwater is damaged could lead to less effectiveness of the wave blocking function of the structure and further decreased function. Each effect is described below.

Decreased Wave Blocking Capability of the Breakwater During Sea Level Rise Ocean waves will be more able to pass over the breakwater at high tide as water levels rise with SLR. However, this breakwater crest is conceived at +10 feet NAVD and presently clears the highest high tide (+7.6 feet) by at least 2.4 feet. Sea level would have to rise above the 2.4 feet of freeboard presented by the breakwater at the highest high tide to increase any wave Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 126
transmission over the structure. Therefore, the SLR scenarios of +3.1 feet and +4.8 feet would provide conditions that would allow wave energy over the structure at high tide.

SLR of +3.1 feet would exceed the freeboard by 0.7 feet at the highest high tide and allow some relatively limited amount of wave energy over the structure. The amount of energy would be relatively low as waves passing over the structure would completely break, and their energy would be significantly dissipated before reaching the beach.

SLR of 4.8 feet would exceed the breakwater crest elevation by 2.4 feet thus allowing increased wave energy over the structure. Again, the amount of energy overtopping the structure would be decreased because the waves would break on the structure and their energy would dissipate.

Both of these scenarios would convey waves over the structure only at the highest high tides of the year which occur infrequently, so the frequency of this occurrence would be rare. So, during most times the breakwater would still effectively block waves. Also, the combined probability of having high waves occur simultaneously with the highest possible tides of the year at those timeframes is even lower.

The breakwater function may decrease over time, but that decrease is modest and not a constant condition, but rather an episodic condition occurring only during extreme events. The long-term function of the structure should remain effective over time.

Adaptive actions that can be taken to preserve the function of the breakwater to block waves would be to raise the crest elevation the same amount as sea level rise to compensate for its effects, and possibly add more sand to the salient. Increasing the crest elevation can be done by adding rock on the crest using similar equipment as that which built the structure originally. The revetment base may need to be designed to be wider than needed initially to accommodate the addition of rock on the crest and slopes at a later date for adaptation.

Greater Wave Forces on the Breakwater That May Cause Damage and Require Repair Sea level rise will result in deeper water at the breakwater toe location over time which enables higher waves to break on the structure. Higher waves impart higher levels of energy on the breakwater, thus increasing the stresses on the rock structure more over time. This may increase wear and damage to the breakwater over time thus triggering damage, increased maintenance and/or resulting in decreased function.

The breakwater is conceived to be capable of withstanding significant storm conditions (e.g., the 100-year coastal storm wave condition) for present-day ocean water levels but will need to be designed to be high enough and of sufficient stone size to also function during future conditions.

The crest elevation and rock size will need to be tested with numerical and physical models to confirm its performance under existing conditions, and how far into the future it can sustain function. The City will need to determine the desired future condition for the reef’s performance.

The City of Oceanside reef project (GHD 2021) considered how their alternative could be adapted to perform under future SLR scenarios up to 2 feet. The City may wish to consider this option and then decide how far into the future their reef needs to function. The reef can also be augmented by being raised with adding larger stones along the crest over time, which would enlarge the footprint. This action is entirely feasible and would render the reef able to function under higher water levels and higher wave conditions in the future. However, it will add costs to the project in future as maintenance, repair, and improvement.

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In addition, sand may need to be added to the salient overtime to keep up with sea level rise. The beach will naturally rise in elevation as water levels rise, but eventually the water level may rise high enough to squeeze the beach area into a such a narrow band as to be less effective at protecting the backshore. In that instance the City may need to add sand to the salient to provide sufficient distance of waves from infrastructure on the beach.

4.4. General Assessment of Overall Project Concept Feasibility The three design concepts were evaluated for multiple factors that are described qualitatively. A simplified scoring matrix presents their relative positions compared to one another on the following page in
Table 4-10. Each design alternative is technically feasible, but they perform at different levels for certain factors.

Overall, the North Beach multi-benefit emergent breakwater project outperforms the other alternatives due to its sand retention benefits, costs, economic benefits, ability to be permitted, and resilience/adaptability.

As shown in
Table 4-10 below, the ranking results show that the North Beach concept is ranked highest overall followed by Capistrano Shores and State Beach which tie. This simple exercise may help support the City in its decision making efforts to prioritize advancing the sand retention design concepts to the next phase.

All three beaches generate non-market value benefits from replenishment in the tens of millions:
• North Beach would generate about $203 Million in benefits compared to $89 Million in costs,
• Capistrano Shores would generate about $114 Million in benefits compared to $60 Million in costs, and
• State Beach would generate about $160 Million in benefits compared to $89 Million in costs.

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Therefore, North Beach has potentially greater economic benefits than the Capistrano Shores and State Beach concepts. Given the various considerations for each project, these results suggest that North Beach would see the most benefits from replenishment if only one project proposal is chosen for advancement.

Preserving San Clemente’s beaches generates significant benefits over the next 25 years plus, which is indicative of the acute need to maintain San Clemente’s beaches to sustain its economy, especially at North Beach. Moreover, these results are robust, with compelling results even considering uncertainty in the efficacy of the breakwaters at reducing erosion. The North Beach Concept is a higher value investment in public funds.

Table 4-10: Design Concepts Scorecard
Concept Name
Sand
Retention
Prediction
Costs Economic
Benefits
Ease of
Permitting
Resilience/
Adaptability
Total Score (15
Possible
Points)
Relative
Rank Based on
Sum of Points
North Beach
Multi-Benefit
Emergent
Breakwater
3 1 3 3 3 13 1
Capistrano
Shores
Multi-Benefit
Submerged
Breakwater and
“Speed Bumps”
3 2 2 1 2 11 2
State Beach
Multi-Benefit
Emergent
Breakwater
3 1 2 2 3 11 2
Rank:
• 3 – High level of feasibility
• 2 – Moderate level of feasibility
• 1 – Low level of feasibility
The ranking in the right-hand column is not a score value but is based on the sum of points. The concept with the most points wins the highest rank.

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5. Recommendations and Next Steps
The recommended next steps of the Project are to:

1. Select and refine the preferred project to advance as a pilot project.

2. Refine the conceptual design to reduce costs while still maximizing benefits of retaining sand.

3. Apply/Obtain for funding to take that project to the next step of preliminary engineering (30 percent, depending on budget and need) and numerical modeling.

4. Evaluate and integrate results of the offshore sand search for a source as close as possible to San Clemente.

5. SCUBA-dive the preferred site to confirm its seabed habitat constraints

6. Design and model the project with a suitable numerical model to test its function and refine the design.

7. Conduct environmental review of the project under CEQA and NEPA.

8. Proceed through 65 percent design incorporating any changes identified as appropriate from numerical modeling and model the design in a physical laboratory.

9. Apply for permits and continue the design through the 90 percent level.

10. Respond to permit agency yards requests for information and continue the design to the 100 percent level.

11. Proceed through 100 percent design incorporating any changes identified as appropriate from physical modeling and permit agency feedback and requirements.

12. Make any final changes to the design as the Final Design package.

13. Issue a Bid Advertisement or Invitation to Bid to marine contractors for bidders on construction.

14. Continue to conduct public outreach and stakeholder input through Project design.

Regular meetings with both stakeholders and the public are necessary to see the concept through to completion.

15. Build the project.

16. Monitor the project’s effects for a minimum of one year prior to construction (and hopefully more) and for several years (5 to 10) after construction.

17. Identify any modifications needed to the project to optimize its performance and/or eliminate adverse impacts.

18. Perform any repair and maintenance that may be required.

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This work is anticipated to take several years to complete and potentially repeated funding cycles to implement. However, the result will be an investment to improve the condition of the City’s beaches and may also serve as a regional example to others as a pathway forward for coastal resilience. Funding options are presented below for the City’s consideration.

5.1. Regional Funding Options
The BCA results outlined in Table 5-1 provide the information needed to pursue grant funding opportunities to implement this project. This Feasibility Study serves as a basis for funding decisions in the future. Federal, state, local, and special tax district funding opportunities are discussed below.

5.1.1. Federal
Federal agencies require BCRs for project feasibility determinations and to secure funding. Many federal agencies have climate adaptation programs which include funding for coastal resilience actions such as beach nourishment and retention features. These agencies and their programs have different focus areas, such as housing, habitat, or defense, so applicants should be aware of each program objective, eligibility, and criteria.

The list below and in Table 5-1 are not exhaustive; however, the lists provide some indication of federal programs applicable to the City of San Clemente. • The United States Department of Transportation’s (US DOT’s) PROTECT program is focused on transportation infrastructure including highways and railways, both of which are at risk from coastal erosion. California Department of Transportation (Caltrans) also participates in this program.
• The National Fish and Wildlife Fund (NFWF) provides funding for projects that increase coastal resilience, as does NOAA’s National Coastal Resilience program. These programs emphasize “greener” strategies such as dune restoration, which has been successfully implemented at many sites in Southern California.
• USFWS provides funding for coastal resilience projects that protect, restore, or enhance coastal and wetland habitat. Beaches which provide significant habitat, especially for threatened and endangered species, could be competitive applicants. While local governments are eligible for the Coastal Program, only state agencies may apply for the National Coastal Wetlands Conservation Program.
• The United States Department of Housing and Urban Development (HUD) allocates funds to geographic areas categorized as “Most Impacted and Distressed,” which includes California, to reduce the impact of future disasters. Community Development Block Grant funds require a Community Development Block Grant Mitigation (CDBG-MIT) Plan for eligibility.
• The FEMA Building Resilient Infrastructure and Communities (BRIC) Program is a highly competitive grant program that supports states, local communities, tribes, and territories as they undertake hazard mitigation projects to adapt and build resilience to risks from natural disasters. The BRIC Program emphasizes capability and capacity-building; encouraging and enabling innovation, including multi-hazard resilience or nature-based solutions; promoting partnerships; enabling large, systems-based projects; maintaining Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 131
flexibility; and providing consistency. The program provides up to $50 Million for projects funded by the national competition.
• The Department of Defense (DOD) provides funding to communities adjacent to military bases and training areas for projects that benefit the community and “Military Installation Resilience.” Due to the presence of Marine Corps Base Camp Pendleton, the City is eligible for the Defense Community Infrastructure Program (DCIP) and Readiness and Environmental Protection (REP) Challenge program. The City is encouraged to coordinate with representatives at Camp Pendleton prior to application.

Federal programs require or encourage matching funding from local and state government.

Applicants should focus on the federal agencies’ main interest when determining if a project is competitive. For example, the US DOT’s main interest is protecting critical infrastructure, including roads and rail lines near the coast, so the project must clearly protect transportation infrastructure.

Table 5-1 reflects federal funding opportunities as of December 2024, but it should be noted federal priorities are being re-evaluated in 2025, and as always funding allocations are subject to change.

5.1.2. State
The State of California has been proactive in addressing climate change and coastal resilience.

The California State Coastal Conservancy (CSCC), Ocean Protection Council (OPC) and CCC continue to provide funding for numerous coastal projects, promoting nature-based solutions similar to those supported by NOAA and NFWF. Proposition 4 funding is available through the CSCC, and they are currently considering applications.

These agencies also encourage LCP development with coastal communities, which may be required to qualify for funding. The City has successfully obtained a CCC grant for the development of the current Feasibility Study and follow on funding may be available from this agency.

Caltrans, with a mandate similar to US DOT’s, focuses on protecting transportation infrastructure.

Given the location of the rail line along the San Clemente shoreline, pursuing these funds could be beneficial. Caltrans also collaborates with the US DOT’s PROTECT program.

Table 5-2 lists specific State funding opportunities.

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Table 5-1: Federal Funding Opportunities
Program Department/
Agency
Purpose URL Funding
PROTECT US DOT Protect Transportation
Infrastructure
https://www.fhwa.dot.gov/environment/protect/discretionar y/
$1.4 B FY 2022 to
2026
National Coastal Resilience
Fund NFWF Increase Resilience through Nature
https://www.nfwf.org/programs/national-coastal-resiliencefund$140 Million in FY24
National Coastal Resilience NOAA Increase Resilience https://coast.noaa.gov/funding/bil/ncrf/overview.html $575 Million in FY23
Coastal Program USFWS Coastal Habitat
Conservation https://www.fws.gov/program/coastal $6 Million in FY23 National Coastal Wetlands
Conservation Program USFWS Coastal Habitat Conservation https://www.fws.gov/coastal/coastalgrants/ $10.8 Million in FY24 CDBG-MIT Program HUD
Increase resilience
and reduce loss of life
and property
https://www.hudexchange.info/programs/cdbgmit/overview/ $12 Billion BRIC FEMA Community
Resilience
https://www.fema.gov/grants/mitigation/building-resilientinfrastructure-communities $1 Billion in FY23

DCIP DOD OLDCC
Community resilience
in military supporting
communities
https://oldcc.gov/defense-community-infrastructureprogram-dcip $100 Million in
FY24
REPI Challenge DOD
Climate resilience in
military supporting
communities
https://www.repi.mil/Buffer-Projects/REPI-Challenge/ $30 Million in FY25
Notes:: 1URL = Uniform Resource Locator,
2FY = fiscal year
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Table 5-2: State Funding Opportunities
Program Agency URL
LCP CCC https://www.coastal.ca.gov/lcp/grants/
Various California State Coastal Conservancy https://scc.ca.gov/grants/ Protect Caltrans/US DOT https://dot.ca.gov/programs/local-assistance/fed-and-state-programs/protect Various State Parks, Division of Boating and Waterways https://dbw.parks.ca.gov/?page_id=28715 Various Ocean Protection Council https://opc.ca.gov/funding

5.1.3. Local
In California, local governments may raise funds through taxation, levy, and assessment. Table 5-3 indicates several measures that can be utilized in California. These mechanisms including property tax, levies sales taxes, transient occupancy taxes, and vacancy taxes (increases) require a two-thirds vote from the relevant constituency. Tax levies for school districts have a lower threshold to pass, requiring a 50 percent majority. Additionally, property tax levy must compete with education measures for voter approval, as voters will consider their overall tax burden when approving or rejecting a measure.

Table 5-3: Local Funding Opportunities
Funding Mechanism Advantages Notes
Tax Options
Sales Tax Raises funds from visitors Requires two-thirds votes if City initiated; 50% +1 is if community initiated; does not include lodging and most groceries.

TOT Local tax on overnight stays City only has 3 hotels at present; short-term rentals also pay TOT. 5 new hotel projects are in the works in the City so this option may be viable in the future Use Tax (e.g., parking fees) Taxes use directly May discourage low-income households Property Tax Levies Consistent revenue source Two-thirds vote; only taxes local residents and not visitors Local Districts
Climate Resilience Districts
(CRDs)
Consistent revenue; geared
specifically towards resilience
Two-thirds vote; only taxes local residents
Geologic Hazard Abatement
District (GHAD)
Focuses on geologic hazards Proposition 218 limits GHADS for use on public property (e.g., beaches) Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 134
A property tax provides a relatively stable source of revenue, whereas sales and transient occupancy taxes vary depending upon the business agency and other factors that influence tourism (e.g., pandemics). When financing a large capital project, where a steady stream of revenues is required, a property tax-based scheme can be a significant advantage. However, one clear disadvantage of property tax schemes is that the burden is placed mostly or entirely on local homeowners. Many beach communities in south Orange County welcome visitors from all over the state, and from out of state and abroad. A district that focuses on property tax revenues alone will not be taxing visitors. Alternatively, sales, use, and transient occupancy taxes (TOTs) require visitors from out-of-the City or district to pay. TOTs in particular focus on visitors and TOT revenues go to local entities, typically the City, or County if unincorporated.

5.1.4. Special Tax Districts
In addition to taxes levied on the entire local jurisdiction, tax districts can be created via ballot measure, such as CRDs and GHADs. Each tax district has a specific purpose. The type of tax district used will vary by City and depend on several factors, including which homeowners will pay the tax and how the tax revenues can be used.

CRDs (resourceslegacyfund.org) allow local communities to generate funding through a more targeted approach. For example, residents living close to a coastal hazard or eroded beach can form a CRD to finance projects, including capital outlays. A GHAD is similar in many ways to a CRD. However, California law treats these two entities quite differently; a GHAD is a private group and, as such, is restricted by Proposition 218 and subsequent litigation. Under Proposition 218, a GHAD can fund only private benefits that accrue directly to the members of the GHAD. This limits a GHAD’s ability to fund projects that restore beaches, which are public below the mean high-tide line in California.

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6. Conclusions
The City of San Clemente has eroding beaches and is vulnerable to damages and adverse impacts now and in the future. The City has actively pursued solutions to these problems since the City Sea Level Rise study in 2019, followed by the Coastal Resilience Plan in 2021, LCP Update documents, and this NBFS in 2022-2025. The City also placed 237,000 cubic yards of sand in 2024 from planned and opportunistic projects.

Recently, the OCTA has initiated their own short- and mid-term planning efforts for their rail infrastructure as well as responded to emergency issues along their right of way, OC Parks has developed their Regional Strategic Plan, the USACE has initiated nourishment in San Clemente, and SANDAG has added south Orange County cities including San Clemente to their next Regional Beach Sand Project III Feasibility Study. Beach erosion within San Clemente has drawn a lot of attention and there are multiple sand replenishment projects currently in development.

The City initiated this NBFS in 2022 to generate solutions that can be resilient and sustainable in the future. A public process vetted an initial long list of potential concepts to solve erosion at some of the most highly eroded beaches. After multiple iterations of public input and discussion, three concepts rose to the top of the list for consideration. This report assesses the feasibility of implementing the three different nature-based shoreline adaptation projects within the City of San Clemente. The projects are the:
• North Beach Multi-Benefit Emergent Breakwater;
• Capistrano Shores Multi-Benefit Submerged Breakwater and “Speed Bumps”, and • State Beach Multi-Benefit Emergent Breakwater.

Each project is feasible to implement to widen beaches as a Phase 1 effort to enhance beach building (nourishment). Each is a structural sand retention solution coupled with beach nourishment. Each is anticipated to succeed in holding sand for long periods after placement in the lee of the structure and to retain sand better than other City beaches into the more distant future.

Phase 2 of implementing living shorelines is proposed at the North Beach site, and throughout other locations within San Clemente that possess wider beaches than other sites. Shorecliffs, the southern City beach (Boca Del Canon reach) and State Beach area are other candidate sites to establish living shorelines over time.

The assessment considered opportunities and constraints (pros and cons), predicted performance, costs, economic benefits, ability to secure permits, ability to fund, and resilience/adaptability over time.

The ranking of the projects based on a variety of criteria is shown below. • Rank #1 – North Beach Multi-Benefit Emergent Breakwater; • Tied for Rank #2 – Capistrano Shores Multi-Benefit Submerged Breakwater and “Speed Bumps” and State Beach Multi-Benefit Emergent Breakwater.

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The rankings consider substantial information and estimates. However, more study, design, and analyses are required to further advance a preferred option. The preferred option should be vigorously pursued as proof of concept to protect the San Clemente coastline as a supplemental and companion strategy to beach sand replenishment alone.

Several suggestions can increase the City’s probability of success as listed below.

First, the City needs to analyze and utilize results of the search for high quality offshore sand in the vicinity. Finding a high quality sand source closer to the City than north Orange County or Oceanside will reduce overall costs and increase the project benefits. This search was completed in mid-2025 and results indicate sand may be available off of Camp Pendleton and north Orange County to nourish San Clemente, but further analyses may be needed to confirm the findings.

Second, marine biologists should SCUBA-dive the proposed footprint of the North Beach Breakwater and sand salient sites to confirm the seabed habitat condition and potentially revise the concept to avoid impacts to reef while also enhancing less productive seabed areas.

Third, the concept design of the multi-purpose reef should be refined to reduce the volume of rock and the resulting project cost. A design team should evaluate the reef position relative to shore and its crest elevation to optimize the structure dimensions and minimize rock quantities needed.

The City may also research multiple rock suppliers to identify the most cost-effective options or consider other structural alternatives such as pre-cast reef modules. ECOncrete or an equivalent product should be considered for inclusion in the materials to build the breakwater to enhance habitat colonization of the site.

Fourth, the City will accomplish more with funding from the State. Applying for and securing State funding for the next phase will enable them to leverage cost sharing in moving the project forward.

Fifth, the City should continue building partnerships with other agencies and consensus within the community to increase project momentum and profile. Funding, approvals, and successes are all more viable with increased support of the public input and other agencies.

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7. References
AMEC. 2005. Regional Beach Sand Project, Year 4, Post-construction Monitoring Report for Intertidal, Shallow Subtidal, and Kelp Forest Resources and Comprehensive Analysis Report (2001-2005). AMEC Earth & Environmental, Inc. .

Beuzen, T., I. L. Turner, C. E. Blenkinsopp, A. Atkinson, F. Flocard, and T. E. Baldock. 2018. "Physical model study of beach profile evolution by sea level rise in the presence of seawalls." ScienceDirect (ScienceDirect, Coastal Engineering) 136 (June 2018): 172- 182.

Bruun, P. 1954. "Coast erosion and the development of beach profiles." By Beach Board Erosion, Tech. Mem. 44: 1-79. US Army Corps of Engineers.

Bruun, P. 1962. "Sea-level rise as a cause of shore erosion." In J. Water Harbors, by P Bruun, Div. 88: 117-130. Proceedings of the American Society of Civil Engineers.

California Coastal Commission. 2021. "Nature-Based Adaptation Strategies." California Coastal Commission. 2025. "Nature-Based Adaptation Strategies. Public Review Draft. September 2025."
California Ocean Protection Council . 2024. California Sea Level Rise Guidance: 2024 Science and Policy Update. California Ocean Science Trust.

CFC. 2024. City of San Clemente Beach Monitoring Program Spring 2024 Beach Profile Survey Report.

City of San Clemente & Moffatt & Nichol. 2019. "City of San Clemente Sea Level Rise Vulnerability Assessment."
City of San Clemente. 2001. "Coastal Resiliency Plan." San Clemente. —. 2024. "Press Release: Beach Sand Replenishment Project Near Pier Resumes." October

24. Coastal Environments. 2014. Coastal Processes and Hydraulic/Hydrology Studies for Doheny State Beach. Ninyo & Moore.

Coastal Frontiers Corporation. 2025. "Beach Monitoring Program Spring 2025 Beach Profile Survey Report. August 2025."
Coastal Frontiers Corporation. 2005. "City of San Clemente Beach Monitoring Program - Spring 2005 Beach Profile Survey Report." Chatsworth.

Coastal Frontiers Corporation. 2024. "City of San Clemente Beach Monitoring Program Fall 2023 Beach Profile Survey Report." San Clemente, CA.

Coastal Frontiers Corporation. 2007. "City of San Clemente Beach Monitoring Program Spring 2007 Beach-Profile Survey Report." Chatsworth, CA.

Coastal Frontiers Corporation. 2001. "City of San Clemente Beach Monitoring Program-Fall 2001 Beach Profile." Chatsworth.

Dean, Robert G. 1991. "Equilibrium Beach Profiles: Characteristics and Applications." Journal of Coastal Research 7(1) 53-84.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 138
Dugan, J. H., D M Hubbard, M D McCrary, and M O Pierson. 2003. "Coastal and Shelf Science

58." The response of macrofauna communities and shorebirds to macrophyte wrack subsidies on exposed sandy beaches of southern California Estuarine, 25-40.

Everest International Consultants. 2013. "Orange County Coastal Regional Sediment Management Plan."
Everts, C.H. 1994. Shore and Beach Management Tactics Evaluation and Recommendations, Shoreline Erosion Assessment and Atlas of the San Diego Region, Vol. I. Sacramento, California: California Department of Boating and Waterways.

Flick, R. 1993. The Myth and REality of Southern California Beaches. Shore & Beach.

Foster, M. S., and D. R. Schiel. 1985. The Ecology of Giant Kelp Forests in. California: A Community Profile. Vol. 85. U.S. Fish Wildl. Serv. Biol. Rep.

GHD. 2021. City of Oceanside Beach Sand Replenishment and Retention Device Project.

Oceanside, CA.

International Coastal Management. 2023. RE:Beach "Living Speed Bumps" Conceptual Design.

Oceanside, CA.

Kahl, D., L. Vulis, J. Schubert, and B. Sanders. 2024. Characterizing Longshore Transport Potential and Divergence of Drift to Inform Beach Loss Trends. Coastal Engineering.

King, Phil. 2024. "Personal Communication with Moffatt & Nichol." Marine Taxonomic Services. 2023. "Marine Habitat Survey for the San Clemente Shoreline Investigations Project." Accessed December 11, 2003.

Martin, Karen and Melissa Studer. 2022. "Citizen Science on the Beach: Grunion Greeters in California."
Merkel & Associates, Inc. . 2025. Marine Biological Technical Study and Essential Fish Habitat Assessment. Orange County SCOUP. Accessed July 2025.

Moffatt & Nichol and Coastal Restoration Consultants. 2003. "Carpinteria Living Shoreline Project Feasibility Study Report."
Moffatt & Nichol and Everts Coastal. 2001. "Regional Beach Sand Retention Strategy." Moffatt & Nichol. 2019. Capistrano Beach County Park Coastal Resilience Study. —. 2020. Capistrano Beach County Park Sand Compatibility and Use Guidelines. —. 2023. Critical Erosion Hotspots Memorandum.

Moffatt & Nichol. 2023. "Critical Erosion Hotspots Report." Moffatt & Nichol. 1994. "Impacts of Oceanside Harbor on Adjacent Beaches." Draft Report.

Accessed March 1994.
—. 2018. San Onofre State Beach: Surf Beach Long-Term Shoreline Management Alternatives Analysis Report.

National Ocean and Atmospheric Administration (NOAA). 2023. "Digital Coast: Digital Access Viewer." coast.noaa.gov/dataviewer/#/lidar/search.

New York State. 2025. https://hcr.ny.gov/living-breakwaters-project-home.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 139
Newkirk, S., S. Veloz, M. Hayden, B. Battalio, T. Cheng, J. Judge, W. Heady, K. Lea, and M.

Small. 2018. Toward Natural Shoreline Infrastructure to Manage Coastal Change in California. California’s Fourth Climate Change Assessment, California Natural Resource Agency.

Patsch, K., and G. Griggs. 2023. An Evaluation of Sand Transport Rate and Direction(s) in the Oceanside Littoral Cell.
—. 2007. Development of Sand Budgets for California's Major Littoral Cells.

Patsch, Kiki, and Gary Griggs. 2006. "Littoral Cells, Sand Budgets, and Beaches:

Understanding California's Shoreline." Accessed October 2006.

SAIC. 2011. Biological Resources Technical Report for the SANDAG Regional Beach Sand Project II. Technical Review, Science Applications International Corporation.

SAIC. 2006. Coastal Habitat Study, 2003-2005: Influence of Beach Nourishment on Biological Resources at Beaches in the City of Encinitas, California. SAIC.

SANDAG. 2011. Environmental Assessment/Final Environmental Impact Report for the Regional Beach Sand Project II. San Diego Association of Governments.

SANDAG. 1993. Shoreline Preservation Strategy for the San Diego Region. San Diego Association of Governments. Accessed November 1993.

USACE. 1990. Coast of California Storm and Tidal Wave Study, Sediment Budget Report, Oceanside Littoral Cell. Los Angeles, CA.
—. 1991. Coast of California Storm and Tidal Waves Study, San Diego Region. Los Angeles, CA.
—. 2011. San Clemente Shoreline Feasibility Study Orange County, CA.

USACE. 2012. San Clemente Shoreline Feasibility Study, Orange County, California Final Report. USACE.

Vos, et al. 2019. "CoastSat: A Google Earth Engine-enabled Python toolkit to extract shorelines from publicly available satellite imagery." Environmental Modeling & Software.

Ware, Rick. 2002. "Rocky Intertidal Habitat Mapped Off of Mariposa Point by Coastal Resources Management." Accessed May 2002.

Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente Appendix A. Public Meeting #1 Presentation – 09/27/2023 Wednesday, September 27th, 2023
Nature-Based Coastal Resiliency
Project Feasibility Study
Community Meeting
1 Welcome & Introductions
• Cecilia Gallardo-Daly, City Community Development Director • Leslea Meyerhoff, City Coastal Administrator
• Chris Webb, Principal Coastal Scientist, Moffatt & Nichol • Justin Peglow, Coastal Scientist, Moffatt & Nichol
2 Meeting Agenda
•Welcome & Introductions
• PowerPoint Presentation by the Team
•Q&A Session
• 20 - Minute break to review posters around the room
• Complete survey and drop in the box
•Adjourn by 8pm
3 Purpose: Nature Based Coastal Resiliency Study
✓Implement recommendations of the San Clemente:
➢2021 Coastal Resiliency Plan
➢2019 Sea Level Rise Vulnerability Assessment
4 Nature Based Resiliency Study Objectives
✓Identify nature-based projects to reduce coastal erosion ✓Complement USACE 50-year beach sand replenishment project ✓Maximize sand retention to widen available sandy beach area ✓Provide multiple co-benefits: protection, public recreation, habitat ✓Coordinate & collaborate with wide range of stakeholders 5 • Nature Based study initiated in November 2022
• Kickoff February 14, 2023 @ City Beaches, Parks & Recreation Commission • First deliverables April 2023 @ Beaches, Parks & Recreation Commission • Published Critical Erosion Hot Spots Report – June 2023 • Community Meeting Tonight: 9/27/23
• Two additional public outreach meetings are currently planned • Dedicated email address to sign up + stay informed: [email protected] Stakeholder Engagement & Involvement Process
6 Study Deliverables to be Published for Review
• Draft Resiliency Design Concept Report: Available early 2024 ➢Publish for 30-day comment period
• Draft Nature Based Feasibility Study: End of 2024
➢Publish for 30-day comment period & Conduct Public Meeting • Final Nature Based Feasibility Study: End of 2025
➢Publish for Review & Conduct Public Meeting
• Submit Final Study to Coastal Commission by 12/31/25
7 Study Funding
• CCC LCP Planning Grant awarded in 2022 - 2025
• City staff coordinating with CCC staff on an ongoing basis • Statewide Planning Staff, Grant Staff & Local District staff • CCC receives copies of all study deliverables & public notices • City using CCC 2021 Nature Based Adaptation Strategies Memo 8 California Coastal Commission (8/23/21)
Nature-Based Adaptation Strategies Memo
9 California Coastal Commission (8/23/21)
Nature-Based Adaptation Strategies Memo
10 Criteria used to develop Draft Resiliency Concepts
• Critically eroded or Threatened beaches are prioritized. • Is public access available?
• Is Marine Safety (lifeguard) access constrained?
• Are there beach amenities such as restrooms, concessions, etc.? • Is public parking available?
• Is public transit access via train and/or bus available? • Is there native vegetation?
• Are there surf resources?
11 M&N – Justin Peglow & Chris Webb
September 2023
San Clemente NatureBased Coastal Resiliency
Project Feasibility Study
Screening Alternatives
Conceptual Schematics
12 13
• CRITICAL: 3 or more parameters are “critical”, or 2 are “critical” and 2 are “threatened”
• THREATENED: 2 or more parameters are “threatened”, or 1 is “critical”
• STABLE: No parameters are “critical” or only 1 is “threatened” Critical Erosion Hotspots Evaluation Criteria
14 CRITICAL

THREATENED
STABLE
15 16
Small Project Concept

1. Create dune and plant with native vegetation
a. Sand nourishment high on beach berm
b. Educational signage

2. Sand fencing/shims along back beach
Shorecliffs Reach: Option A
Critical
17 2
1 Example of a “Groin”
(28th Street, Newport Beach)
Shorecliffs Reach: Option B
Critical
19 Medium Project Concept

1. Groin at south end of reach

2. Pre-filled sand nourishment along shoreline
2 1
Example of a “Groin Field”
(Newport Beach)
Capistrano Shores Reach: Option A
Critical
21 1
Large Project Concept

1. Groin field along extent of reach
a. Landward notch on groin to allow lateral beach access

2. Pre-filled sand nourishment along shoreline
2 Example of a Breakwater (Santa Monica)
Capistrano Shores Reach: Option B
Critical
23 Large Project Concept

1. Segmented living breakwater with surfable edges

2. Pre-filled sand nourishment along shoreline
1 2
Example of a Wave Energy Dissipator (Reef)
North Beach Reach
Threatened
25 1
4 3
2 1
Large Project Concept

1. Cobble/boulder living reef connected to shoreline

2. Pre-filled sand nourishment along shoreline

3. Sand fencing/shims along back beach

4. Create dune habitat with educational signage
Mariposa Beaches Reach
Critical
26 Large Project Concept

1. Boulder delta/artificial headland connected to shore

2. Pre-filled sand nourishment along shoreline
1 2
Example of Additional/Larger Pier Piles
San Clemente Pier Huntington Beach Pier
Linda Lane & Pier Bowl Sub-Reach
Threatened
This area to directly
benefit from USACE
nourishment
28 Small-to-Medium Project Concept

1. Passive living shoreline area with educational signage a. Sand fencing/shims along landward edge

2. Additional piles installed on pier to slow sand movement 1 2
T-Street Sub-Reach
Stable
This area to directly
benefit from USACE
nourishment
29 No Project Concept Proposed

1. Natural reef connected to shore makes this reach one of the most stable in the City

2. T-Street Reef is an existing nature-based sand
retention feature (wave energy dissipation)
Boca Del Canon Reach
Stable
This reach is likely the
first to receive indirect
(downcoast) benefit
from USACE
nourishment
30 Small Project Concept

1. Passive living shoreline areas with educational signage a. Sand fencing/shims along landward edges
1 1
State Beaches Reach
Stable
31 Small-to-Medium Project Concept

1. Portions of existing vegetation along back-beach converted to living shoreline/dune systems a. Explore various restoration options (e.g., active, passive, hybrid, etc.) 1 1
1 1
1 1
1 Cyprus Shores Reach
Critical
32 Large Project Concept

1. Cobble/boulder living reef connected to shoreline

2. Pre-filled sand nourishment
1 2
Q & A
33 Public Input & Survey
➢ The City would like to hear from you
➢ What do you think of the draft design concepts?
➢ Review the exhibits around the room
➢ Complete the survey form provided
➢ Drop your completed survey in the box
➢ Provide us with any other feedback important to you
34 Join the Project Mailing List:

[email protected]
All deliverables available on City Webpage
https://www.san-clemente.org/LCP
35 Thank you for your time tonight!
36 Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente Appendix B. Public Meeting #2 Presentation – 02/29/2024 Nature-Based Coastal Project
Feasibility Study
Community Meeting #2
Thursday, February 29th, 2024
• Mark Enmeier, Mayor ProTem
•Andy Hall, City Manager
• Leslea Meyerhoff, AICP, Coastal Administrator
• Chris Webb, Principal Coastal Scientist, Moffatt & Nichol •Justin Peglow, Coastal Scientist, Moffatt & Nichol
Welcome & Introductions
Meeting Agenda
•Open House: 4pm - 4:30pm
•Welcome & Introductions: 4:30pm
• Presentation by the Team: 4:45pm
• Listening Session & Q&A : 5:45pm
•Adjourn: By 7pm
Nature Based Study Objectives
• Identify nature-based projects to retain sand & widen sandy beach • Complement existing & planned beach sand replenishment projects ✓ USACE 50-year beach sand replenishment project
✓ SANDAG RBSP III
✓ SCOUP Projects
✓ South Orange County Collaborative Beach Sand Project? • Design for co-benefits: widen beach, enhance recreation & natural resources • Coordinate & collaborate with full range of stakeholders Purpose of Community Meeting #2
• Share revised preliminary designs and some new concepts • Some designs have been dropped from consideration
• Public input: drop cobble delta concept
• Receive community input: revise and/or fine tune designs • Present draft design report in Spring 2024 for public review What we heard from the Community
• Protection of the sandy, walkable public beach is a top priority • The sandy beach is essential to a quality of life in San Clemente • San Clemente’s beach is an important asset and amenity • Beach supports long-term community vitality and character • Community does not want experimental or unproven solutions February 2024
San Clemente NatureBased Coastal Resiliency
Project Feasibility Study
Revised Alternative
Conceptual Schematicsfor
Draft Feasibility Report
M&N – Justin Peglow & Chris Webb
7 Design Concept Criteria
Design Components Include:

1. Community Resilience Benefit

2. Recreational Preservation or Enhancement

3. Fish, Wildlife, and Ecological Protection / Benefit

4. Proof of Concept

5. Transferability / Scalability Beyond the Funded Project Phased Approach
The Entire Effort Depends on Wide Beaches to Succeed.
• Current Phase – Large-Scale Beach Sand Nourishment
• Phase 1 – Sand Retention with Beach Sand Nourishment
• Phase 2 – Living Shorelines with Beach Sand Nourishment After Wide Beaches Exist
Current Phase – Large-Scale Beach Sand Nourishment
• U.S. Army Corps of Engineers 50-Year Project.
• San Diego Association of Governments (SANDAG) with Orange County Parks and Dana Point.
• Supplement With a Sand Compatibility and Opportunistic Use Program (SCOUP) for Smaller-Scale Nourishment Opportunities.

Nourishment
North of USACE
50-Yr Project
Footprint
Nourishment
South of USACE
50-Yr Project
Footprint
San Clemente Pier

Sand Volume Needed = 7 Million CY
• Assumes 250-foot-wide beach is needed everywhere for 5.94 million square feet of beach over 4.5 miles of City beach.
• Assumes that 1.5 cy of sand is needed to create one square foot of new beach (per USACE 1984).
• Accounts for existing beach widths per City surveys in 2023. • Existing Beach = 1.44 million square feet in area.
• Need to create 4.50 million square feet of new beach. • 4,500,000 sf X 1.5 cubic yards/sf = 6,750,000 cubic yards of sand needed for nourishment.

Phase 1: Sand Retention with Nourishment
• Retention can be either:
• Shore-perpendicular – Groins, speed bumps, headlands, peninsulas • Shore-parallel – Breakwaters, and/or
• Hybrid (both) - Reefs
• Groins perform best if sand moves in one direction (south) • Breakwaters work well if sand moves in both directions (south and north)
• Reefs work similar to breakwaters but create less beach Example of a
“Groin”
(28th Street,
Newport
Beach)
Example of a
Breakwater
(Santa Monica)
Example of a Reef
(Australia)
Source: International Coastal Management, Queensland, Australia Reef With Tombolo
(Australia)
Source: International Coastal Management, Queensland, Australia Example of A
Pier Pile
Cluster
San Clemente Pier Huntington Beach Pier
Less Dense Cluster More Dense Cluster
Pros
&
Cons
Sand Retention
Feature
Orientation to
Shore
Best for Sand
Movement
Pros Cons
Shore
Perpendicular
(headland,
peninsula, groin)
Perpendicular,
Attached to Shore
In One Direction,
Either North or South
Less Expensive, Easier
to Remove, Can Create
Wide/Long Beach
Lower Probability of
Success at San Clemente
Breakwater Parallel, Offshore In Both Directions Higher Probability of Success, Works During
SLR, Surf?
More Expensive, Harder
to Remove
Reef Parallel, Offshore In Both Directions High Probability of Success if Large,
Surfable, Aesthetics
Expensive and Hardest
to Remove, High Tide
Limits, SLR Limits
Speed Bump Both, Onshore Either Way Least Expensive, Easiest to Remove
Least Effective, Upper
Beach Only
Pier Pile Cluster Perpendicular,
Attached to Shore
In Both Directions Similar Lower Cost, Easy
to Remove, Worksin
SLR
Less Effective than
Breakwaters & Reefs
San Clemente Conditions
• Sand moves in both north and south directions depending on swell. • Breakwaters would have the best effect and create the largest beaches. • Reefs would also create beaches but smaller than those behind breakwaters. • Groins would not work as well as breakwaters.
• Consider breakwaters with surfable edges (hybrid breakwater + reef).

Phase 1: Sand Retention with Nourishment
• Install Multi-Purpose Breakwaters to Retain Beach Sand. • Target Locations for Breakwaters: Capistrano Shores, North Beach, and the South End of City Between State Beach and Cottons.
• Determine Priority of Breakwaters at Capistrano Shores, North Beach, and the South End.
• Likely Implement One as a Pilot for Monitoring, then Implement More if Monitoring Shows Positive Results.

Capistrano Shores Reach: Option A 23
Capistrano Shores Reach: Option B 24
North Beach Reach
Cyprus Shore Reach 26
Linda Lane & Pier Bowl 27
Phase 2: Living Shorelines with Nourishment
After Wide Beaches Established
• Longer Term Strategy to Maintain sand supply reserves in the City • Consider Living Shorelines (Dune Habitat) as Beaches Widen • Design to maintain access and beach use
• Locate at landward edge of Beach after it is widened
• No Conflict With Recreational Use (beach is wide)
• Target Locations: Shore Cliffs, North Beach, Pier Bowl, and State Beach Shorecliffs Reach 29
North Beach Reach 30
Linda Lane & Pier Bowl Sub-Reach 31
Boca Del Canon Reach 32
State Beaches Reach 33
Phased Approach - Timing

PHASES TIMING
Phase 0 - Large-Scale Beach Sand Nourishment 3 to 7 years – Depends on Funding and Rate of Progress Phase 1 – Sand Retention with Beach Sand
Nourishment
7 to 12 years – Depends on Funding, Progress,
Monitoring Results, and Public Support
Phase 2 – Living Shorelines with Beach Sand
Nourishment After Wide Beaches Established
7 to 15 years - Depends on Success of Nourishment and
Rate of Beach Widening; Can be Concurrent with Sand
Retention Projects
Phases and Timing
Public Input
The City & Team would like to hear from you!
➢ Have you had a chance to review exhibits in the room? ➢ What do you think of the draft design concepts?
➢ What are your favorites?
➢ Did we miss any concepts?
➢ Community feedback is important to this process.

Listening Session
+
Q & A
Upcoming Project Study Deliverables
•Draft Design Concept Report = Publish in Spring 2024
•Draft Nature Based Feasibility Study = Publish Late 2024 / Early 2025 •Final Nature Based Feasibility Study = Publish at end of 2025 •Submit Final Study to Coastal Commission by 12/31/25
Join the Project Mailing List
[email protected]
All deliverables available on City Webpage
https://www.san-clemente.org/LCP
Thank you for your time!
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente Appendix C. Public Meeting #3 Presentation – 07/18/2024 Nature-Based Coastal Project
Feasibility Study
Community Meeting #3
Thursday, July 18th, 2024
• Leslea Meyerhoff, AICP, Coastal Administrator
• Chris Webb, Principal Coastal Scientist, Moffatt & Nichol •Justin Peglow, Coastal Scientist, Moffatt & Nichol
Welcome & Introductions
Nature Based Study Objectives
• Identify locally appropriate opportunities to retain sand & widen beach • Complement existing & planned beach sand replenishment projects ✓ USACE 50-year beach sand replenishment project
✓ SANDAG RBSP III
✓OCTA Sand Placement Project
✓ SCOUP Projects
✓ South Orange County Collaborative Beach Sand Project
• Design for co-benefits: widen beach, enhance recreation & natural resources Purpose of Community Meeting #3
• Share revised design concepts
• Receive community input
• Revise and /or fine tune designs
• Present draft design report in late 2024 for public review M&N – Justin Peglow & Chris Webb
July 2024
San Clemente NatureBased Coastal Resiliency
Project Feasibility Study
Revised Alternative
Conceptual Schematics for
Draft Feasibility Report
5 Design Concept Criteria
Design Components Include:

1. Community Resilience Benefit

2. Recreational Preservation or Enhancement

3. Ecological Benefit

4. Proof of Concept

5. Transferability / Scalability Beyond the Funded Project Phased Approach
The Entire Effort Depends on Wide Beaches to Succeed.
• Current Phase (Phase 0) – Large-Scale Beach Sand Nourishment • Phase 1 – Sand Retention with Beach Sand Nourishment
• Phase 2 – Living Shorelines After Wide Beaches Exist
Current Phase (0) –Beach Nourishment Efforts in 2024+

1. U.S. Army Corps of Engineers 50-Year Project. (251,000 cy every 5-6 yrs)

2. SANDAG RBSP III with Orange County Parks and Dana Point (TBD but City likely to request 300k cy or more)

3. OCTA Planning to deliver 540,000 cubic yards this year (2024)

4. Sand Compatibility and Opportunistic Use Program (SCOUP) (30k cy at North Beach this July)

5. OC Parks – 20,000 cy upcoast in Capo Beach July 2024 Phase 0 Project Locations
(30,000 cy)
(540,000 cy)
(251,000 cy)
Sand Volume Needed Over 50 Years:~7 Million CY
•Assumes 250-foot-wide beach.
•Based on 1.5 cy of sand = 1 sqft of new beach.
•Soft goal of 140,000 cy per year => or 700,000 cy
every 5 years.

San Clemente Conditions
• Sand moves in both north and south directions depending on swell. • Breakwaters would have the best effect and create the largest beaches. • Reefs would also create beaches but smaller than those behind breakwaters. • Small headlands could create additional beach width, slow sand movement. • Impermeable groins would not work as well as breakwaters. • Consider breakwaters with surfable edges (hybrid breakwater + reef).

Phase 1: Sand Retention with Nourishment
• Install Breakwater Systems to Retain Beach Sand.
• Target Locations for Breakwaters: North End and South End of City. • Determine Priority of Breakwaters at Capistrano Shores, North Beach, and State Beaches South.
• Likely Implement One as a Pilot for Monitoring, then Implement More if Monitoring Shows Positive Results.

City Surf Map and Proposed Phase I Projects
Beach Nourishment /
Living Shorelines
Passive Living Shoreline
Various Dune Treatments
Proposed Phase 0, I, and II Project Locations
Phase 1 Project Concept

1. “Speed Bump” (Mini-headland)

2. Pre-filled sand nourishment and eventual shoreline

3. Submerged Vegetated Habitat Breakwater
1 1
3 2
Capistrano Shores Reach
Real-world concept example: Santa Monica Breakwater (CA) Real-world concept example: Salt Creek Mini-Headland (CA) Capistrano Shores Living Breakwater + Sand “Speed Bumps” Phase I
North Beach Reach
Phase 1 Project Concept

1. Multi-benefit emergent surfable breakwater

2. Pre-filled sand nourishment and eventual shoreline
2 1
Real-world concept example: Palm Beach Reef (AUS)
North Beach Multi-Benefit Breakwater
Phase I
18 State Beach Reach
Phase 1 Project Concept

1. Multi-benefit emergent surfable breakwater

2. Pre-filled sand nourishment and eventual shoreline
1 2
Real-world concept example: Palm Beach Reef (AUS)
State Beach Multi-Benefit Breakwater
Phase I
Phase 2 – Living Shorelines and Additional Beach Sand
Nourishment After Wide Beaches Establish
• Install Various Treatments of Living Shorelines (Dune Habitat) as Beaches Grow.
• These Serve as Sand Reservoirs for Coastal Storm Event Protection and Create Important Habitat.
• Design Dunes to Not Conflict With Recreational Beach Use (Rear of the Beach After it is Widened).
• Target Locations for Dunes are throughout the City.

Shorecliffs Reach
Phase 2 Project Concept

1. Create dune ecosystem and plant with native vegetation

2. Sand fencing/shims along back beach

3. Sand nourishment on beach
2 1
3 20
Real-world concept example: Cardiff Living Shoreline (CA) Shorecliffs Living Shoreline
Phase II Project Example
Phased Approach - Timing

PHASES TIMING
Phase 0 - Large-Scale Beach Sand
Nourishment
Initiated in 2024 and will be ongoing as part of shoreline management and coastal resiliency strategy in the City long-term Phase 1 – Sand Retention with Beach Sand
Nourishment
5 to 10 years – Depends on Funding, Public Support, and Monitoring Results
Phase 2 – Living Shorelines with Beach Sand
Nourishment After Wide Beaches Established
10+ years - Depends on Success of Nourishment and Rate of Beach Widening; Can be Concurrent with Sand Retention Projects Phases and Timing
Public Input
The City & Team would like to hear from you!
➢ Have you had a chance to review exhibits in the room? ➢ What do you think of the updated draft design concepts? ➢ Did we get the locations right?
➢ Did we miss any concepts?
➢ Community feedback is important to this process.

Draft Nature Based Design Concept Memo
➢ Published Late July 2024
➢ Please submit comments online to the
QR Code or web address →
➢Comment period open through
September 6, 2024
➢ Community input will be incorporated
into Draft Feasibility Study published in
late 2024
www.san-clemente.org/LCP
Join the Project Mailing List
[email protected]
All deliverables available on City Webpage
https://www.san-clemente.org/LCP
Thank you for your time!
Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente Appendix D. Alternatives Screening Graphics
M&N – Justin Peglow & Chris Webb
August 3, 2023
San Clemente NatureBased Adaptation Pilot
Project Feasibility Study
Screening Alternatives
Schematics Rev. 3
Internal
working/administrative
draft, not for public use
or distribution
Light Touch
Restore vegetated scrub area to resilient living shoreline:
• Direct targeted nourishment high on beach
• Raised to +20/+25’ MLLW el.
• Install sand fencing/shims to prevent blowing onto RR • Remove ice plant, scrub, nonnatives
• Seed with native, sand accreting, resilient vegetation • Build protective cobble toe with existing material at the beach Shorecliffs Reach - 1
Internal working/administrative draft, not for
public use or distribution Critical*
Shorecliffs Reach - 2
Internal working/administrative draft, not for
public use or distribution
Medium-Scale/Large Project
Nourishment of reach + installation of short groin at south end of reach to capture longshore sand transport
Critical*
Capistrano Shores Reach - 1
Large Project
Nourishment of reach + installation of groin field along reach to allow for longshore transport sand capture
Internal working/administrative draft, not for
public use or distribution Critical*
Capistrano Shores Reach - 2
Large Project
Nourishment of entire reach + install of submerged
living breakwater to dissipate wave energy and
promote natural beach accretion
Internal working/administrative draft, not for
public use or distribution Critical*
North Beach Reach
Large Project
Nourishment of reach + installation of nearshore boulder reef • Dissipates wave energy further off beach, builds beach naturally shoreward and creates calm wading area
• Creates surfing recreation for beach without existing surfing quality wave resource
Proximity of OCTA
train terminal, bus
Internal working/administrative draft, not for
public use or reproduction Threatened*
Mariposa Beaches Reach
Large Project
Nourishment + installation of boulder delta/artificial headland connected to shore • Use 4-ton rock to create a gently sloping feature, terminating farther offshore • Dissipates wave energy to build beach naturally in front of it and on upcoast side(s) • Creates/improves surfing recreation for area with numerous access points • Restores beachside access for City Marine Safety Department Internal working/administrative draft, not for
public use or distribution Critical*
Linda Lane & Pier Bowl Sub-Reach
Medium Touch
Install additional econcrete piles on pier
• Helps slow longshore transport and
capture downdrift sediment
• Supports additional complex intertidal
habitat space
Light Touch
Install low-cost, minimal approach, educational living shoreline area • Install sand fencing, shims, and plant seeds of native dune species • Locate high on beach within an area that does not result in any net loss of recreational towel space (in conjunction with USACE sand placement), also in zone less frequented by beachgoers
• Design to naturally intercept aeolian transport of native and USACE sand to store and retain on back beach
• Rope off to deter public disturbance and prevent driving of vehicles over area • Install interpretive and educational signage focusing on the importance and utility of nature-based solutions in establishing healthy, resilient shorelines and expanding habitat This area to directly
benefit from USACE
Internal working/administrative draft, not for
public use or distribution Threatened*
T-Street Sub-Reach
No Intervention
• Existing natural reef connected to shore makes this
reach one of the most stable along the City’s stretch
• Serves as an example and study site of nature-based
approaches that are effective to retain sand on San
Clemente beaches
Internal working/administrative draft, not for
public use or distribution Stable*
This area to directly
benefit from USACE
Boca Del Canon Reach This reach is likely the
first to receive indirect
Internal working/administrative draft, not for
public use or distribution Stable*
Light Touch
Install one or two low-cost, minimal approach, educational living shoreline areas • Install sand fencing, shims, and plant seeds of native dune species • Locate high on beach within an area near special status species to promote habitat growth; also in zone less frequented by beachgoers (less nearby access) • Design to naturally intercept aeolian transport of native and USACE sand to store and retain on back beach
• Rope off to deter public disturbance and prevent driving of vehicles over area • Install interpretive and educational signage focusing on the importance and utility of nature-based solutions in establishing healthy, resilient shorelines and expanding habitat Stable*
State Beaches Reach - 1
Using one or more of
the various existing
Internal working/administrative draft, not for
public use or distribution
Light Touch/Medium-Scale
Restore one or more pocket(s) of existing “Upland
Scrub” to living shoreline/dune habitat(s) where beach
is wide enough to support it:

Light touch
• Remove non-native veg, cover with native sand,
plant/seed with native/resilient dune species
• Partial roping off of restoration areas to dissuade
human use, but access to area(s) still available
• Install interpretive and educational signage about
project and dune ecosystem benefits
• Acts to trap and accrete windblown sand naturally
and build beach; dissipates storm wave runup
Medium-Scale
Same as “Light Touch” above, except:
• Remove all existing vegetation (non-special status)
and back-beach scrub area
• Add larger quantities of imported sand, establish
dune system/field with native/resilient species
• Creates a larger sand reservoir and provides more
resilience to storm energy
Stable*
State Beaches Reach - 2
Internal working/administrative draft, not for
public use or distribution
Large Project
Nourishment + low, notched econcrete or rock short
groin field along reach
• Notched/spaced material placement at low
elevation has sand capturing effect of traditional
groins but does not starve downcoast areas of
sediment (allows material passage)
• Econcrete material can be utilized to create a
richer/more diverse intertidal habitat space than
traditional groins
Cyprus Shores Reach - 1
Medium-Scale/Large Project
Nourishment + installation of minigroin to collect sediment upcoast of Cyprus Shores/Cyprus Cove private
community beach access point (North
Gate)
• Allows for upcoast sediment
accretion along structure to
establish more permanent
recreational beach space near
accessway
• Targeted nourishment along full
length of reach to reestablish
beachside passageway from San
Clemente to Cotton’s Point
Internal working/administrative draft, not for
public use or distribution Critical*
Cyprus Shores Reach - 2
Internal working/administrative draft, not for
public use or distribution Critical*
Large Project
Nourishment + installation of nearshore reef/boulder delta in front of Cyprus Shores community
• Dissipates wave energy to build beach and create calm wading area landward and on both sides of structure
• Improves surfing recreation for area with wave resource degraded by coastal erosion
• Puts direct weight on toe of landslide to stabilize cliff and housing development; additional weight added over time via beach accretion provides further stability
• Targeted nourishment along full length of reach to reestablish beachside passageway from San Clemente to Cotton’s Point Final San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente Appendix E. San Clemente Sand Retention Performance Summary 1 555 Anton Boulevard, Ste. 400
Costa Mesa, CA 92626
(657) 261-2699
www.moffattnichol.com

MEMORANDUM
To: Leslea Meyerhoff; City of San Clemente
From: Chris O’Day and Chris Webb; Moffatt & Nichol
Date: March 27, 2025
Subject: Sand Retention Performance of Nature Based Resiliency Alternatives M&N Job No.: 221572
1 Introduction
The City of San Clemente (City) has developed three conceptual sand retention design alternatives through the ongoing Nature-Based Adaptation Project Feasibility Study. These conceptual designs include two primary sand retention structure types: an offshore shore-parallel submerged breakwater and an emergent multi-benefit breakwater. These structures are designed for the primary purpose of retaining sand on the adjacent beaches in San Clemente to counteract the City’s ongoing erosion problems.

Offshore sand retention structures create a wider beach in the lee of the structure called a salient. The purpose of this memorandum (memo) is to analyze the conceptual design alternatives and approximate the area of the salient that may form. Methodologies from the Regional Beach Sand Retention Strategy (Moffatt & Nichol and Everts Coastal 2001) were primarily used for the salient area estimates. These methods were tailored to the Southern California wave climate using empirical data from existing structures along the Southern California coast.

Section 1.1 analyzes the offshore, shore-parallel submerged breakwater concept. The steps taken to calculate a salient area are described and results are discussed. Section 1.2 analyzes the multi-benefit emergent breakwater concept. Two separate methodologies are described and discussed in this subsection to calculate salient area. Section 2 presents the results of these analyses and offers conclusions.

1.1 Submerged Offshore Breakwater
The first conceptual sand retention alternative analyzed is an offshore, shore-parrel breakwater (Figure 1).

The breakwater would be approximately 2,000 feet (ft) long and 100 ft wide along its entire length. The breakwater would also be considered “submerged” with a top elevation of the crest of the structure at approximately 0 ft relative to North American Vertical Datum of 1988 (NAVD88). As a result, the structure would not be visible from the shoreline (i.e., it does not penetrate the water surface under calm seas conditions) other than during spring low tides when it may extend up to 2 ft above the water surface. The structure would be placed in approximately 15 ft of water and positioned 1,500 ft offshore of the Capistrano Shores community.

This structure is designed to form a salient, or a bulge in the beach in its lee (number “2” in Figure 1), caused by slowing of longshore sediment transport and reduction of incident wave energy. It would create both recreational and habitat opportunities and locally protect the Capistrano Shores area. This beach has experienced significant beach erosion and undermining that has threatened shoreside infrastructure, and the wider beach would help protect this threatened infrastructure from storm events.

M&N #221572
Sand Retention Performance Memorandum
2 Figure 1: Conceptual Schematic for Capistrano Shores Breakwater This structure can be considered a classical offshore breakwater in the context of coastal engineering. The methodology for calculating salient area behind a Southern California breakwater was sourced from the Regional Beach Sand Retention Strategy prepared for the San Diego Association of Governments (Moffatt & Nichol and Everts Coastal 2001). Two separate methodologies of calculating salient area are described, one using the anticipated length and width of the salient and the other using the volume of the breakwater.

Both methods were used to calculate a salient area for the breakwater concept and are described in the following subsections.

1.1.1 Breakwater Calculation Method and Results
The calculation was completed using the following methodology as outlined by the Regional Beach Sand Retention Strategy (Moffatt & Nichol and Everts Coastal 2001):

1. Develop a dimensionless ratio between the structure crest length (L) over the structure’s offshore distance (Y).

𝐿
𝑌
=
2000 𝑓𝑡
1500 𝑓𝑡 = 𝟏. 𝟑𝟑

2. Identify the wave transmission coefficient (Kt) based on the crest elevation height above mean sea level over the structure depth (C). This quantifies the amount of wave energy that can pass over and/or through the structure. Kt is considered to be a function of exposure or submergence of the structure crest with Kt and C values as follows shown in Table 1.
•
• Table 1: Kt as a function of C.

M&N #221572
Sand Retention Performance Memorandum
3 Kt C
0 0.5

0.2 0.2

0.4 -0.1

0.8 -0.3
𝐶 =
−2.6 𝑓𝑡
20 𝑓𝑡 = −𝟎. 𝟏𝟑
𝐾𝑡 = 𝟎. 𝟒

3. Use Figure 2 to evaluate the relationship between L/Y and the dimensionless ratio between anticipated salient width (ys) over the structure’s offshore distance (Y) based on a Kt of 0.4.
𝑦𝑠
𝑌
= 𝟎. 𝟑
Figure 2: L/Y versus ys/Y for Southern California Breakwaters (Moffatt & Nichol and Everts Coastal 2001)

4. Calculate the anticipated salient width (ys) by using the structure’s offshore distance (Y). 𝑦𝑠
1500 𝑓𝑡 = 0.3
𝑦𝑠 = 0.3(1500 𝑓𝑡) = 𝟒𝟓𝟎 𝒇𝒕

5. Calculate the anticipated salient length (xs) based on the empirical relationship established between salient width and salient length in Figure 3 (Moffatt & Nichol and Everts Coastal 2001).

M&N #221572
Sand Retention Performance Memorandum
4 𝑥𝑠 = 6𝑦𝑠
𝑥𝑠 = 6(450 𝑓𝑡)
𝑥𝑠 = 𝟐𝟕𝟎𝟎 𝒇𝒕
Figure 3: Salient length (xs) versus salient width (ys) (Moffatt & Nichol and Everts Coastal 2001)

6. Estimate the salient area (As) assuming the plan shape of the salient would be a triangle, seaward projection to be equal to ys and its alongshore length to be equal to 6ys.

𝐴𝑠 = 3𝑦𝑠
2 𝐴𝑠 = 3(450 𝑓𝑡)
2 𝑨𝒔 = 𝟔𝟎𝟕, 𝟓𝟎𝟎 𝒇𝒕𝟐 = 𝟏𝟑. 𝟗 𝒂𝒄𝒓𝒆𝒔

7. Estimate the volume of the breakwater (Vb) using the geometry of the structure.

𝑉𝑏 = 𝟐, 𝟔𝟔𝟖, 𝟕𝟓𝟎 𝒇𝒕𝟐 = 𝟗𝟖, 𝟖𝟒𝟐 𝒄𝒖𝒃𝒊𝒄 𝒚𝒂𝒓𝒅𝒔

8. Estimate the salient area (As) using the empirical relationship between L/Y and As/Vb shown in Figure 4. Units of As/Vb must be divided by Y1/3 to calculate As in ft2.

M&N #221572
Sand Retention Performance Memorandum
5 Figure 4: L/Y versus As/Vb for Southern California Breakwaters (Moffatt & Nichol and Everts Coastal 2001)
𝐴𝑠/𝑉𝑏 = 3.4

3.4 𝑌
1 3
=

3.4 1500
1 3
= 0.297
𝐴𝑠 = 0.297(𝑉𝑏
) = 0.297(2,668,750 𝑓𝑡2
)
𝑨𝒔 = 𝟕𝟗𝟐, 𝟔𝟔𝟓 𝒇𝒕
𝟐 = 𝟏𝟖. 𝟐 𝒂𝒄𝒓𝒆𝒔

1.1.2 Discussion
Two salient areas of approximately 610,000 ft2to 790,000 ft2, or 14 to 18 acres respectively, were calculated for the submerged offshore breakwater concept. In order to avoid downcoast erosional effects of this salient being accumulated, the structure should be adequately pre-filled to artificially create a salient of this size.

1.2 Multi-Benefit Breakwater
This concept is an emergent rocky reef, multi-benefit breakwater situated between the north end of the North Beach Reach and the south end of the Capistrano Shores Manufactured Home community (Capistrano Shores community) Reach as shown in Figure 5. It would be constructed of armor stone material and have a “barbell” shape, shore-parallel design.

The footprint of the “barbell” shaped structure would be approximately 1,300 ft long, 350 ft wide in the center along the midpoint, and 700 ft wide at the ends. It would be situated approximately 900 ft offshore to form a salient, or a bulge in the beach. The submerged, flared sides of the structure would gently slope down around the seaward and side edges for surfing, and the main segment would have a steeper slope on the shoreward and seaward sides of the structure to dissipate wave energy. The crest along the top of the reef/breakwater would be emergent at all times at an approximate design crest height of +10 ft NAVD88.

This implies that under current sea level conditions, at the lowest spring tides about 11-12 ft of the M&N #221572
Sand Retention Performance Memorandum
6 breakwater crest would be exposed and at the highest spring tides approximately 2-3 ft of the breakwater crest would be exposed. The crest would be approximately 600 ft long and 10 ft wide with the edges angled (“doglegged”) at about 45 degrees towards shore for the last 200 ft of each end. This concept was taken from the City of Oceanside Sand Replenishment and Sand Retention Project (GHD 2021).

A prefill of sand would be placed (number “2” in Figure 5) that mimics the anticipated salient that would eventually form leeward of the structure. Sand pre-filling of the salient is done to prevent littoral drift from accumulating in the deposit causing deprivation to the downcoast beach. The width and area of the anticipated salient is calculated herein.

Figure 5: Conceptual Schematic for North Beach Multi-Benefit Breakwater Since this concept is a hybrid rocky reef/breakwater, the salient area was estimated using two separate methods. The first calculation was completed under the assumption the structure would act more similarly to an offshore emergent breakwater; the second calculation was completed under the assumption the structure would act more similarly to an offshore reef. These salient areas were also estimated based on methodologies described in the Regional Beach Sand Retention Strategy (Moffatt & Nichol and Everts Coastal 2001).

1.2.1 Breakwater Calculation Method and Results
First, the salient area was estimated based on the assumption that the multi-benefit breakwater structure would act more similarly to an offshore emergent breakwater. This assumes that the breakwater crest is 600 ft in length based on the dimensions of the emergent shore-parallel middle portion of the breakwater.

The calculation was completed using the following methodology as outlined by the Regional Beach Sand Retention Strategy (Moffatt & Nichol and Everts Coastal 2001):

9. Develop a dimensionless ratio between the structure crest length (L) over the structure’s offshore distance (Y).

𝐿
𝑌
=
600 𝑓𝑡
900 𝑓𝑡 = 𝟎. 𝟔𝟔
M&N #221572
Sand Retention Performance Memorandum
7 10. Identify the wave transmission coefficient (Kt) based on the crest elevation height above mean sea level over the structure depth (C). This quantifies the amount of wave energy that can pass over and/or through the structure. Kt is considered to be a function of exposure or submergence of the structure crest with Kt and C values as follows shown in Table 1.

𝐶 =

7.38 𝑓𝑡
15 𝑓𝑡 = 𝟎. 𝟒𝟗
𝐾𝑡 = 𝟎

11. Use Figure 2 to evaluate the relationship between L/Y and the dimensionless ratio between anticipated salient width (ys) over the structure’s offshore distance (Y). 𝑦𝑠
𝑌
= 𝟎. 𝟒𝟖

12. Calculate the anticipated salient width (ys) by using the structure’s offshore distance (Y). 𝑦𝑠
900 𝑓𝑡 = 0.48
𝑦𝑠 = 𝟒𝟑𝟎 𝒇𝒕

13. Calculate the anticipated salient length (xs) based on the empirical relationship established between salient width and salient length in Figure 3 (Moffatt & Nichol and Everts Coastal 2001).
𝑥𝑠 = 6𝑦𝑠
𝑥𝑠 = 6(430 𝑓𝑡)
𝑥𝑠 = 𝟐𝟓𝟖𝟎 𝒇𝒕

14. Estimate the salient area (As) assuming the plan shape of the salient would be a triangle, seaward projection to be equal to ys and its alongshore length to be equal to 6ys.

𝐴𝑠 = 3𝑦𝑠
2 𝐴𝑠 = 3(430 𝑓𝑡)
2 𝑨𝒔 = 𝟓𝟓𝟒, 𝟕𝟎𝟎 𝒇𝒕
𝟐 = 𝟏𝟐. 𝟕 𝒂𝒄𝒓𝒆𝒔

1.2.2 Reef Calculation Method and Results
The salient area was also estimated based on the assumption that the hybrid rocky reef/breakwater structure would act more similarly to an offshore artificial reef. The calculation was completed using the following methodology as outlined by the Regional Beach Sand Retention Strategy (Moffatt & Nichol and Everts Coastal 2001):

15. Estimate the reef footprint area assuming that this would be the submerged footprint of the hybrid breakwater/reef.
• 𝑅𝑒𝑒𝑓 𝑎𝑟𝑒𝑎 ≈ 12 𝑎𝑐𝑟𝑒𝑠
M&N #221572
Sand Retention Performance Memorandum
8 •

16. Estimate the salient area (As) based on Figure 6 which shows the salient area as a function of the reef area.
• 𝑨𝒔 = 𝟑𝟒𝟖, 𝟑𝟖𝟎 𝒇𝒕𝟐 ≈ 𝟖 𝒂𝒄𝒓𝒆𝒔
Figure 6: Salient area as a function of reef plan area developed using empirical data from Southern California reefs (Moffatt & Nichol and Everts Coastal 2001)

1.2.3 Discussion
Based on the assumed dimensions and that the multi-benefit breakwater structure would perform similarly to an offshore emergent breakwater, the salient area was estimated to be 554,700 ft2 or 13 acres. In order to avoid downcoast erosional effects of this salient being accumulated, the structure should be adequately pre-filled to artificially create a salient of this size.

Based on the assumed dimensions and that the multi-benefit breakwater structure would perform similarly to an offshore artificial reef, the salient area was estimated to be approximately 350,000 ft2 or 8 acres. It is worth noting that greater uncertainty exists in the artificial reef estimates than in the submerged offshore breakwater estimates. This is due to the lack of detailed bathymetry over local reefs. As a result, the comparison data for the southern California wave climate was rough and relied on results from laboratory studies and empirical data from Japan, New Zealand and Australian coastlines when establishing the approach to calculate salient area. This estimate also assumes that the proposed structure would be constructed similar to the naturally occurring reef examples which are shore connected structures. The conceptual design proposed for San Clemente is not shore connected and it is therefore more realistically modeled as a breakwater.

Multi-Benefit Breakwater
M&N #221572
Sand Retention Performance Memorandum
9 Figure 7: Comparison of salient and tombolo bounds defined by the ratio L/Y for five investigators (Moffatt & Nichol and Everts Coastal 2001).
2 Conclusion
A salient area of 610,000 ft2to 790,000 ft2(14 – 18 acres) was calculated for the submerged offshore breakwater concept and a salient area of 554,700 ft2(13 acres) for the multi-benefit breakwater was calculated. Figure 8 shows the anticipated salient that would form behind the submerged breakwater concept. A pre-fill nourishment approximately the size of the anticipated salient would be required during construction in order to avoid downcoast erosion impacts. To create this sized beach approximately 1 CY of sand would be needed for every 1 ft2 of beach space, so 610,000 – 790,000 CY of sand would need to be added to the beach. Figure 9 shows the anticipated salient that would form behind the multi-benefit breakwater concept. Similarly, 1 CY for every 1 ft2 of beach space would be needed as pre-fill. This means approximately 560,000 CY of sand would be needed for pre-fill for this concept.

M&N #221572
Sand Retention Performance Memorandum
10 Figure 8: Anticipated salient behind the submerged breakwater concept.

Figure 9: Anticipated salient behind the multi-benefit breakwater concept.

M&N #221572
Sand Retention Performance Memorandum
11 A concern for each design is the formation of a tombolo behind the structure. A tombolo is defined when sand buildup in the lee becomes attached to the structure and blocks sand from moving downcoast, resulting in unwanted erosional effects. Tombolo formation can be mitigated by adjusting the dimensions and location of the structure appropriately. This should be considered when finalizing the conceptual designs.

Draft San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente Appendix F. Economic Methodology and Results
Draft San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 1 City of San Clemente Nature-Based Adaptation Project Feasibility Study: Economics Methodology and Results
Prepared by Dr. Phil King and Lorenzo Spaccarelli
April 8, 2025
Overview
The beaches in or near the City of San Clemente have been steadily eroding for several decades. San Clemente’s beaches are enormous drivers of economic activity in the region, and their preservation is critical to maintaining the health and well-being of its residents and visitors. To this end, the City of San Clemente developed the ongoing Nature-Based Adaptation Project Feasibility Study, which has proposed several conceptual sand retention design alternatives. These projects propose breakwaters along with a standard sand replenishment cycle; models suggest that these combined initiatives will result in several acres of additional sand for visitors to enjoy. The additional sand and the slowed erosion rate will have tangible benefits that can be measured via an economic analysis, especially in sections of the beach that currently have little sand.

This analysis will focus on three beaches: Capistrano Shores, North Beach, and South End/Cyprus Shores.

Table 1 presents the estimated costs of these projects.

Table 1: Costs of Projects
Site Project Cost
North Beach $89,013,257
Capistrano Beach $60,342,327
State Beach $89,013,257

2.0 What is a Benefit Cost Analysis?
Benefit-Cost Analysis (BCA) is a systematic approach for estimating the economic value of different policy or project options by comparing their expected costs and benefits. For hazard mitigation projects, the BCA determines the future risk-reduction benefits of a project and weighs those benefits against project costs (Federal Emergency Management Administration [FEMA] 2024). A BCA results in a Benefit-Cost Ratio (BCR), a direct comparison of expected benefits against projected costs. A BCR over 1.0 is generally considered cost-effective although some agencies mandate higher ratios.

2.1 What Benefits do Beaches Provide?
Beaches provide a number of benefits to the public, as well as to private property:

Draft San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 2 • Recreation: Recreation is an important driver for beaches in and around San Clemente.

Economists generally divide these (recreational) benefits into two broad categories. o Non-market benefits: Economists define “nonmarket value” in terms of a visitor’s willingness to pay for a “free” good or service such as a day at the beach. Based on current studies this value is approximately $62 a day.
o Carrying Capacity: The US Army Corps of Engineers and US Forest Service developed the concept of “carrying capacity” for recreational assets such as campgrounds, playgrounds, picnic areas or beaches. Applying this concept, the State of California has approved a 100 square foot area per person for carrying capacity for the health, safety and well-being of beach visitors. Although this carrying capacity may be exceeded (typically on summer weekend), this reduces the overall experience and hence nonmarket value. o Economic Impacts: Estimates of spending, jobs and taxes, which many people associated with beaches, are considered economic impacts and may also include indirect or “multiplier” effects, e.g., a lifeguard earns a salary and spend some of it at local businesses, generating more jobs and taxes.
• Protection of Public Property, Infrastructure
o Roads and Railroads: The US Army Corps of Engineers as well as State Agencies recognizes the role that beaches play in protecting critical infrastructure. In San Clemente and Capistrano Shores, both highway one and the railroad line directly behind areas of critical beach erosion. Preventing this erosion lowers the likelihood that this vital infrastructure will be damages. Economists can weigh these benefits in terms of expected (avoided) costs. Caltrans has developed methods to estimate the value of a lost trip due to highway closures.
o Other Infrastructure: Beaches also protect parking lots, lifeguard towers, bathrooms and other infrastructure necessary for a beach/park to function properly. As beaches erode, the likelihood that these structures will be damaged increases. • Protection of Private Property: Beaches provide buffers to protect private property, both private businesses and residences. Moreover, since the sand from beach nourishment migrates a full analysis of a nourishment project should include any benefits as sand migrates, e.g., at Capistrano Shores.
• Ecological/Habitat Value: Beaches provide/protect habitat for a variety of flora and fauna. The State of California has been active in efforts to restore dunes and other sensitive coastal habitat, often at a very high cost. These costs also should be evaluated in a benefit cost analysis.

Note that the U.S. Army Corps of Engineers limits recreational benefits to no more than 50% of the total benefits due to a project.

2.2 Discounting
Typically, economic benefit/cost analysis discounts future costs and benefits, based on the theory that future benefits/costs are worth less than the same benefit/cost today. The discount rate is applied in various economic analyses, which enables policymakers to compare and evaluate the net present value (NPV) of different projects or investments. The choice of discount rate is critical in a benefit/cost analysis. Currently there is no consensus among economists as to the proper discount rate or even if a discount rate should Draft San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 3 be used. Even a relatively low discount rate can imply that benefits and costs for future generations are valued far less than current benefits; many economists have argued that the social discount rate should be lower than the market cost of capital. For example, when projecting out to the year 2100, even a relatively low discount rate, such as 3 percent (%), implies that a $100 benefit is worth about one-tenth of today’s valuation. The impact of discount rates on future value is especially significant when it comes to environmental damages, which are often expensive or impossible to fix after the damage has occurred.

This study used two different discount rates for the analysis: 0% and 3%. Associated graphs and charts present the results undiscounted (0% discount rate).

3.0 Preliminary Analysis

3.1 North Beach
A preliminary analysis of North Beach indicates that recreational benefits are sufficient to justify the costs of a reef. However, recreational benefits are only a part of the total benefits, and a full benefit analysis would also include an estimate the following benefits, which are likely to be significant:
• Recreational Value: A reef would significantly increase the recreational value of the beach greater than the cost of the project.
• Protection of beach infrastructure: The restrooms, lifeguard towers, parking and other infrastructure at north beach is vulnerable to damage in case of a storm or sever erosion event.

The benefits from nourishment could be significant are worth evaluating. • Protection of the Rail Line: Protection of the rail line at N. San Clemente Beach (and Capistrano Shores): Any interruption of the rail line would cause a significant disruption. The County is currently considering armoring portions of this rail line, which would be expensive. Armoring could also lead to beach erosion which would lower the recreational and ecological value of the beach. • Ecological Value: A reef may enhance ecological value though impacts on marine life need to be evaluated.

Replenishment of North Beach is likely to yield the greatest benefits of any beach in our model in terms of recreational value given its location and access:

3.2 North Beach Recreational Value
Our preliminary analysis assumes an annual attendance of 200,000 visitors per year, which is quite modest given the location of this site. It is quite possible that this site would be more popular if protected. Note these visitors are not distributed evenly throughout the year but instead visitation peaks during summer months, on weekend, midday. The recreational model employed here accounts for this variation by applying attendance estimates from nearby beaches with similar patterns.

The high losses in recreation value result from North Beach’s high relative annual attendance and narrow remaining width of the beach in 2024 (approximately 12.6 feet). Without replenishment, North Beach will disappear completely in 2046, with cumulative NMV losses reaching about $205 million by 2050, as shown in 1 below.

Draft San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 4 Figure 1: Expected loss in recreational benefits due to coastal erosion with and without project.

North Beach will see a significant benefit from replenishment. The cumulative value of replenishment is about $203 million undiscounted and $129 million with a 3% discount rate. Please note that these are only for recreational benefits. If one includes other benefits, the total benefits will be higher, possible by a significant amount given the value of the rail line.

3.3 Capistrano Shores
As with North Beach, a preliminary analysis of Capistrano Shores indicates that recreational benefits are sufficient to justify the costs of a reef. However, recreational benefits are only a part of the total benefits, and a full benefit analysis would also include an estimate the following benefits, which are likely to be significant:
• Recreational Value: A reef would significantly increase the recreational value of the beach greater than the cost of the project.
• Protection of beach infrastructure: The restrooms, lifeguard towers, parking and other infrastructure at Capistrano Shores is vulnerable to damage in case of a storm or sever erosion event. The benefits from nourishment could be significant are worth evaluating. • Protection of the Rail Line: Protection of the rail line at N. San Clemente Beach (and Capistrano Shores): Any interruption of the rail line would cause a significant disruption. The County is currently considering armoring portions of this rail line, which would be expensive. Armoring could also lead to beach erosion which would lower the recreational and ecological value of the beach. • Ecological Value: A reef may enhance ecological value though impacts on marine life would need to be evaluated.
$-
$50,000,000
$100,000,000
$150,000,000
$200,000,000
$250,000,000
-
50,000
100,000
150,000
200,000
250,000
Cumulative $ Losses
# of persons
Year
North Beach, Lost Capacity and Cumulative NMV Losses
Unreplenished and Replenished
# of people over capacity Replenished # of people over capacity Cumulative Lost NMV Replenished Cumulative Lost NMV
Draft San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 5 • Protection of Private Property: The reef would also likely protect private property near Capistrano Shores and this benefit should be fully evaluated given the high value of these homes.

Replenishment of Capistrano Shores would produce millions in recreational value. Capistrano Shores already experiences NVM losses due to erosion and overcrowding, as Capistrano Shores is already almost completely eroded with just 2.42 feet of sand remaining. The model of the impacts of erosion and replenishment for Capistrano Shores uses an erosion rate of 0.6 ft/year. Daily attendance data was not available for Capistrano Shores; therefore, the All-Use Beach Profile was used.

The high losses in recreational value primarily result from its narrow initial width. Capistrano Shores expected capacity was exceeded by almost 15,000 in 2024. This number only grows to about 75,000 by 2029, which is when the beach will become entirely depleted in this no-action scenario. Therefore, while erosion is relatively low, the preexisting thin beach results in total NMV losses of about $115 million by 2050 if no action is taken, as can be seen in 2 below.

Figure 2: Expected NMV loss due to coastal erosion with and without replenishment at Capistrano Shores
Replenishment and protection would help Capistrano Shores significantly. With projected replenishment, Capistrano Shores would have a cumulative NMV benefit through 2050 (avoided loss in recreational value) of about $114 million, or $79 million with a 3% discount rate.

Our preliminary analysis assumes an annual attendance of 75,000 visitors per year, which is quite modest given the location of this site. It is quite possible that this site would be more popular if protected. As with North Beach, these visitors are not distributed evenly throughout the year but instead visitation peaks during summer months, on weekend, midday. The recreational model employed here accounts for this variation by applying attendance estimates from nearby beaches with similar patterns. $-
$20,000,000
$40,000,000
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40,000
50,000
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Cumulative $ Losses
# of persons
Year
Capistrano Shores, Lost Capacity and Cumulative NMV Losses Unreplenished and Replenished
# of people over capacity Replenished # of people over capacity Cumulative Lost NMV Replenished Cumulative Lost NMV
Draft San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 6 3.4 State Beach
Our preliminary analysis of State Beach indicates that the increase in recreational value is likely to be quite low given the limited access to this site. The site provides substantial benefits to the following:
• San Clemente State Park (Protection) including parking and campgrounds • The Railroad line
• Residential Property just south of San Clemente State Beach This analysis assumes that 100,000 visitors will go to Capistrano shores if this project is built. Without action, NMV losses through 2050 will total more than $160 million, as shown in Figure 4-6.

Figure 3: Expected NMV loss due to coastal erosion with and without replenishment at the State Beach, not accounting for the breakwater’s impact

4.0 Methods
The analysis in this study combines aspects of the various federal agencies' methodologies with empirical research and established practice specific to California to provide the most accurate estimate of the value of beach replenishment under the Nature-Based Adaptation Project Feasibility Study. It relies on the following key assumptions.
$-
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# of persons
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State Beach, Lost Capacity and Cumulative NMV Losses
Unreplenished and Replenished
# of people over capacity Replenished # of people over capacity Cumulative Lost NMV Replenished Cumulative Lost NMV
Draft San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 7 4.1 Day-Use Value
The recreational value of beaches in California has been studied extensively, typically in terms of Willingness to Pay (WTP) for a trip to the beach. Economists can measure WTP by estimating the travel cost to and from the site (revealed preference) or by asking visitors how much they would be willing to pay (stated choice). Most of the studies cited in Figure 3 below are travel cost models (Parsons 2003). This WTP is typically expressed as a “day-use value.”
In Pendleton et al (2006), the authors present a table of estimates of the day-use value of beaches, mostly in southern California, based on travel cost and contingent choice studies. These estimates of day-use value vary by study and by beach with valuations ranging from $20 to $145 per day (2025 $). The average is $62 per day (2025 $), and the median is $52.1
This method is also consistent with a recent California Coastal Commission decision in Solana Beach (Michael Baker International 2016). Several local coastal programs employed this method in determining the NMV of beaches including: the City of Pacifica, the City of Oceanside, and Ventura County. A study funded by NOAA for the California Coastal Commission (Engel et al. 2015) also recommended this approach.

4.2 Carrying Capacity
With coastal erosion, beaches will lose area; this loss in area will lead to a loss in recreational value as the beach becomes more crowded. The relationship between lost area and lost recreational value can be modeled using the carrying capacity of a given beach. Studies indicate that beachgoers generally require about 100 square feet (sq ft) of space per person or “towel space” (e.g., Sheehan et. al. 2022). However, most beachgoers do not spend an entire day at the beach. While the turnover rate may vary site to site, past estimates use a rate of 1.5 to 2 (King and McGregor 2012). The carrying capacity, therefore, is determined by dividing the area by required towel space and multiplying the result by the turnover rate.

Daily attendance is rarely equivalent to carrying capacity, except during the busiest days in high season.

Therefore, the modeling of erosion impacts needs to adjust for peak days at a given beach. Many beaches are highly seasonal, with more than half of visits taking place in the summer high season. At some of these seasonal beaches, the beach may be nearly at capacity for much of the summer (high utilization), and less busy in the winter (low utilization). Thus, a loss of area would impact the peak season attendance far more than low season attendance. Recreational value depends on attendance, not on area, at least up to the point that the loss in area impacts attendance. To estimate the loss in NMV is to estimate the loss in recreational value due to beach erosion, the methodology in this study follows the USACE guidance (Warren and Rea 1989; CDM Smith Federal Programs 2017; Reclamation Bureau 2010) and assumes a “carrying capacity” of 100 sq ft per person per day. Because attendance is not uniform, the carrying capacity constraint will limit attendance first on the busiest days (e.g., weekends in July and August and the 4th of July); as the beach shrinks, more days will be impacted by limited carrying capacity. In estimating carrying capacity, this study also factored in a conservative turnover rate of 2.5, allowing for more visits per day of shorter length.

Carrying capacity is a daily measure; therefore, the analysis in this study compared changes in carrying capacity to site’s daily attendance. To model attendance, this analysis for the City of San Clemente used daily data from four separate beaches where accurate daily attendance counts were available to create a model: Coronado Shores, Moonlight, Mission Beach, and Imperial Beach. The data used was from an 1 The consumer surplus values in Pendleton et al.’s table are from the following sources: Leeworthy and Wiley (1993), King (2002) – midpoint between two methods, Chapman and Hanemann (2001) – corrected for inflation using the Consumer Price Index, Lew and Larson (2005), Larson (2002), Leeworthy (1995), Sheehan et al (2022), Pendleton et al (2006), Nelsen (2012).

Draft San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 8 upcoming economic analysis report for RBSP III. Despite being in the San Diego region, these beaches have a largely similar attendance profile to the three beaches in San Clemente included in this report. Each of these San Diego beaches had either a digital counter to count each day’s attendance or daily lifeguard estimates. Each day’s attendance was represented as a percentage of that beach’s total annual attendance; these attendance percentages were then averaged to create percentages of the year’s total attendance for each and every day of the year.2 This results in a “Representative Beach Profile,” which could then be easily applied to all beaches in this analysis (as each only had annual attendance estimates) to give attendance per day estimates.

Importantly, considering the crucial nature of weekends as a driver of beach visitors, the data was aligned by day of the week despite the different years, ensuring that the weekend peaks were maintained. The importance of this can be seen clearly below in 3. Without the alignment of the days of the week, many of the highest attendance days could have been averaged out, and many of the peaks would have been lost.

The peaks are essential as they represent the busiest days, which are the first to be constrained by a beach’s falling carrying capacity.

Figure 3: The above graph shows the difference between weekend attendance and weekday attendance over the course of the year in the representative beach profile, composed of Coronado Shores, Moonlight, Mission Beach, and Imperial Beach. The difference between the two trendlines indicates the importance of weekends as peak attendance days for beachgoers.

4.3Estimating Lost Value
To estimate lost value, attendance estimates are compared to the beach’s total capacity. The carrying capacity of the beach is estimated by looking at the rate of erosion in the past and predicting average erosion in future years to see how the beach area diminishes. Beach area was calculated using data from Chris O’Day and Chris Webb, who developed estimates as to the beach area after replenishment and the installation of sand retention mechanisms. Then the beach area is divided by a standard value for necessary 2 All beach attendance data were averaged across at least 2 years; for Coronado Shores, for example, daily counts averaged between 2019 and 2023 were used before calculating the percentage of attendance. Additionally, no beach data from 2020 or 2021 were used for any beach, as those years are not representative.

0.000%

0.200%

0.400%

0.600%

0.800%

1.000%
1-Jan 20-Feb 10-Apr 30-May 19-Jul 7-Sep 27-Oct 16-Dec
Percent of Annual Attendance
Date
Attendance, Weekends and Weekdays
Weekdays Weekends
14 per. Mov. Avg. (Weekdays) 14 per. Mov. Avg. (Weekends) Draft San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 9 space (100 sq ft of space per visitor) and then multiplied by the daily turnover rate (2.5) to give the number of people who can visit the beach and fit comfortably in the beach’s area. (𝐼𝑛𝑖𝑡𝑖𝑎𝑙 𝐵𝑒𝑎𝑐ℎ 𝑊𝑖𝑑𝑡ℎ − 𝐸𝑟𝑜𝑠𝑖𝑜𝑛 𝑅𝑎𝑡𝑒 ∗ 𝑇𝑖𝑚𝑒) ∗ 𝐵𝑒𝑎𝑐ℎ 𝐿𝑒𝑛𝑔𝑡ℎ = 𝐵𝑒𝑎𝑐ℎ 𝐴𝑟𝑒𝑎 𝐵𝑒𝑎𝑐ℎ 𝐴𝑟𝑒𝑎
𝑆𝑝𝑎𝑐𝑒 𝑝𝑒𝑟 𝑃𝑒𝑟𝑠𝑜𝑛 ∗ 𝑇𝑢𝑟𝑛𝑜𝑣𝑒𝑟 𝑟𝑎𝑡𝑒 = 𝐵𝑒𝑎𝑐ℎ 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦
Then, for each beach, each day’s attendance (as predicted by the model or taken from the daily counts) is compared to the calculated carrying capacity of the beach. The sum of visitors expected to exceed carrying capacity throughout the year results in the number of people who couldn’t visit the beach each year because of the limited capacity. To determine the NMV of this lost visitation, the visits are multiplied by value of a visit ($62 per day). Even when carrying capacity is exceeded, the model does not assume that visitors will not go to the beach at all (though they may not) but assumes a loss in value due to crowding for all visitors.

For C representing capacity at each beach, D representing each day’s attendance over the course of the year, and V representing the value of a visit per person ($62):

𝐿𝑜𝑠𝑡 𝑁𝑀𝑉 𝑓𝑟𝑜𝑚 𝑜𝑣𝑒𝑟𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦 = 𝑉 ∗ ∑{
𝐷𝑖 −𝐶,𝐷𝑖 > 𝐶
0,𝐷𝑖 ≤ 𝐶
365
𝑖=1

5.0 Conclusions and Discussion
The benefits/cost ratios for all three projects are above one, indicating that the benefits exceed the cost.

While this report only examines losses through 2050, effective breakwaters will likely reduce the erosion rate by more than half and preserve these beaches for decades longer than the period examined in this report. This analysis also assumes that current infrastructure and access will remain largely the same. If access and infrastructure is improved at each of these sites then the benefits could be significantly higher. The State Beach has great potential given the nearby parking for State Parks, but costs are $20 for an entire day during peak season, but with less costly hourly parking also available. Capistrano Shores has relatively limited access for non-residents.

6.0 References
Parsons, George R. 2003. “The Travel Cost Model.” In: Champ, P.A., Boyle, K.J., Brown, T.C. (eds) A Primer on Nonmarket Valuation. The Economics of Non-Market Goods and Resources, vol 3. Springer, Dordrecht.

Pendleton, L., Kildow, J., and Rote, J. W. 2006. “The non-market value of beach recreation in California.” Shore and Beach, 74(2), 34.

Reclamation Bureau, Interior Department. 2010. "Water and Land Recreation Opportunity Spectrum (Walros): Users' Handbook". Government. Interior Department. https://www.govinfo.gov/app/details/GOVPUB-I27-PURL-gpo79062 Sheehan, Lindsey, Kristina Kunkel, Philip King, Dana Murray, and Nicholas Garrity. 2022. “We’ll take Manhattan: Preserving an urban (Southern California) beach in the 21st century”, Shore & Beach, 90(3), 3-16.

Draft San Clemente Nature-Based Adaptation Project Feasibility Study | City of San Clemente 10 Warren, Roger and Rea, Phillip. 1989. Management of Aquatic Recreation Resources. Gorsuch Scarisbrick Pub.

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