2025-01648 Accepting SAFCA’s Urban Level of Flood Protection Reports (LR25-006) Part 3 — Sacramento City Council, October 21, 2025 (part 1 of 4)

URBAN LEVEL OF FLOOD PROTECTION
ENGINEER’S REPORT

FOR THE

AMERICAN RIVER SOUTH LEVEE SYSTEM
APRIL 2025
FINAL
PREPARED UNDER: SACRAMENTO AREA FLOOD CONTROL
AGENCY, CONTRACT NO. 1588
(Back of title page)

CERTIFICATION
This Engineer’s Report was prepared by the Sacramento Area Flood Control Agency (SAFCA) certification team including Psomas, GEI Consultants, Inc (GEI), Kleinfelder, Mead & Hunt, and MBK Engineers (MBK). The purpose of this report is to support a finding that the American River South Levee System, which was constructed and is owned by the Central Valley Flood Protection Board (CVFPB) and operated and maintained by the City of Sacramento, Sacramento County Maintenance Area 9 (MA9), and the American River Flood Control District (ARFCD), provides an urban level of flood protection (ULOP) in accordance and consistent with the requirements, definitions, and descriptions provided by:

State of California Department of Water Resources (DWR) ULOP Criteria (November 2013), Section 2, EVD-1.

State of California DWR Urban Levee Design Criteria (ULDC) (May 2012), Section 7.0.

The supporting documentation, calculations, data, definitions, limitations, and/or other pertinent information contained or referenced in this report form the basis of this certification. This certification does not constitute a warranty or guarantee of performance, express or implied. The certification is made for the American River South Levee System. Individual certification statements are provided in Appendix A for each ULDC topic, which have been endorsed by the certification team member responsible.
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Water Resources Flood Control Water Rights
WALTER BOUREZ, III, P.E. FOUNDERS:

DON TRIEU, P.E.

DARREN CORDOVA, P.E. ANGUS NORMAN MURRAY
NATHAN HERSHEY, P.E., P.L.S. 1913-1985
LEE G. BERGFELD, P.E. JOSEPH I. BURNS
BEN TUSTISON, P.E. 1926-2021
THOMAS ENGLER, P.E., CFM DONALD E. KIENLEN, P.E.

MICHAEL MONCRIEF, P.E. 1930-2023

NICOLE ORTEGA-JEWELL, PMP
KYLE KNUTSON, P.E.

ANNE WILLIAMS, P.E.

PATRICK HO, P.E.

CERTIFICATION
This certification is provided to the Sacramento Area Flood Control Agency (SAFCA) for the sole purpose of supporting an Urban Level of Flood Protection (ULOP) finding. This certification is made in accordance with the requirements, definitions, and descriptions in the State of California Department of Water Resources’ (DWR) Urban Level of Flood Protection Criteria (November 2013), Section 2, Subsection EVD1 and Urban Levee Design Criteria (ULDC) (May 2012), Section 7.0 Urban Levee Design Criteria.

All information, calculations, definitions, descriptions, restrictions, limitations, or other pertinent data contained or referenced in this document form the basis of this certification. This certification does not constitute a warranty or guarantee of performance, express or implied. This certification is made with respect to the American River South Levee System, as described in the Urban Level of Flood Protection Engineer’s Report, February 2025 (Engineer’s Report).

Limits and Conditions of This Certification
This certification shall expire or become invalid at the earliest time any of the following conditions are met for any portion of the levee system:
 Integrity of the levee system has degraded to the point that the identified improvements will not be adequate to provide an urban level of flood protection, as determined by me, or a duly qualified designated successor.  Discovery of any substantive defect in the condition of any component of the levee system that was not known at the time this certification was made, and which materially affects the system’s ability to provide protection relative to a ii
1-in-200 chance of annual flood, as determined by me, or a duly qualified designated successor.
 20-years from the date of certification or until the ULOP finding is superseded, whichever is sooner, provided that a periodic review of the finding, which may include a full or partial engineering re-evaluation as deemed necessary, is performed every 5 years.

Certification Statement
At the request of SAFCA, as supported by the information contained and referenced within the Engineer’s Report, this is to certify the following:
 Certification of Data and Information – The data and information presented in this report are accurate to the best of my knowledge.
 Certification of Analysis – To the best of my knowledge, the analyses conducted were performed in accordance with DWR’s ULDC and/or sound engineering practices, in a manner consistent with the degree of skill and care ordinarily exercised by members of the civil engineering profession currently practicing in the same locality under similar conditions.

I, Thomas F. Engler, PE, a professional registered civil engineer in the State of California, certify that the aforementioned levee system, as described in this Urban Level of Flood Protection Engineer’s Report, April 2025, provides an urban level of flood protection.

Tom Engler, PE, CFM
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825-6579
____________________________________________ 4/22/2025___ Signature Date
Not Valid Unless Stamped
Expires March 31, 2027
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TABLE OF CONTENTS
Table of Contents ....................................................................................... iii List of Figures .................................................................................................................................... iv List of Appendices ........................................................................................................................... iv Acronyms and Abbreviations .................................................................... vi

1.0 Introduction ........................................................................................ 1

2.0 Description of American River South Levee System ....................... 3

3.0 Physical Description ........................................................................... 3 American River South (left) Levee .................................................................................................... 3 Sacramento River East (left) Levee (SREL) ..................................................................................... 4

4.0 Performance History .......................................................................... 5 American River South Levee ............................................................................................................... 5 Sacramento River East Levee .............................................................................................................. 5

5.0 Evaluation of American River South Levee System ........................ 6 ULDC 7.1: Design Water Surface Elevation ............................................................................ 7 ULDC 7.2: Minimum Top of Levee ............................................................................................. 8 ULDC 7.3: Soil Sampling, Testing, and Logging ................................................................... 8 American River South Levee ............................................................................................................... 9 ULDC 7.4: Slope Stability For Intermittently Loaded Levees .......................................... 10 American River South Levee ............................................................................................................ 10 Sacramento River East Levee ........................................................................................................... 11 ULDC 7.5: Underseepage For Intermittently Loaded Levees ......................................... 11 American River South Levee ............................................................................................................ 11 Sacramento River East Levee ........................................................................................................... 12 ULDC 7.6: Frequently Loaded Levees ..................................................................................... 12 ULDC 7.7: Seismic Vulnerability ................................................................................................ 12 ULDC 7.8: Levee Geometry......................................................................................................... 13 American River South Levee ............................................................................................................ 14 Sacramento River East Levee ........................................................................................................... 14 ULDC 7.9: Interfaces and Transitions ...................................................................................... 14 American River South Levee ............................................................................................................ 15 Sacramento River East Levee ........................................................................................................... 16 ULDC 7.10: Erosion ........................................................................................................................ 17 American River South Levee ............................................................................................................ 17 iv
Sacramento River East Levee ........................................................................................................... 18 ULDC 7.11: Right-of-Way ........................................................................................................... 18 American River South Levee ............................................................................................................ 19 Sacramento River East Levee ........................................................................................................... 19 ULDC 7.12: Encroachments ........................................................................................................ 19 ULDC 7.13: Penetrations ............................................................................................................. 20 ULDC 7.14: Floodwalls, Retaining Walls, and Closure Structures ................................. 21 American River South Levee ............................................................................................................ 21 Sacramento River East Levee ........................................................................................................... 21 ULDC 7.15: Animal Burrows ....................................................................................................... 22 ULDC 7.16: Levee Vegetation .................................................................................................... 22 ULDC 7.17: Wind Setup and Wave Runup ............................................................................ 22 American River South Levee ............................................................................................................ 23 Sacramento River East Levee ........................................................................................................... 23 ULDC 7.18: Security ....................................................................................................................... 23 ULDC 7.19: Sea Level Rise ........................................................................................................... 24 ULDC 7.20: Emergency Actions and Flood Safety Plans .................................................. 24 ULDC 8.0 Operations & Maintenance .................................................................................... 25

4.0 Bibliography ..................................................................................... 27

LIST OF FIGURES
Figure 1. SAFCA Levee Certification, Levee Systems
Figure 2a. Urban Levee Design Criteria, American River South Levee System - American River South Levee Figure 2b. Urban Levee Design Criteria, American River South Levee System – Sacramento River East Levee

LIST OF APPENDICES
Appendix A. Consultant Certification Statements
Appendix B. Independent Panel of Experts Report and Comment Closeout Appendix C. ULDC Design Water Surface Elevation Profiles – MBK Appendix D. American River South ULDC Due Diligence, Geotech – GEI Appendix E. American River South ULDC Due Diligence, Geotech – Kleinfelder Appendix F. American River South ULDC Due Diligence, Geotech – MBK Appendix G. ULDC and FEMA Levee O&M Review Letter – MBK Appendix H. O&M Right of Way Maps – Psomas
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Appendix I. American River South ULDC Due Diligence, Civil/Structural – Mead & Hunt Appendix J. ULDC Required Plans
Appendix J1 – Right of Way Plan – MBK Engineers
Appendix J2 – Encroachment Remediation Plan – MBK Engineers Appendix J3 – Penetrations Exception Work Plan – Mead & Hunt Appendix J4.1 – ARFCD Rodent Control & Abatement Program Appendix J4.2 – City of Sacramento Rodent Abatement and Damage Repair Standard Operating Procedure (SOP)
Appendix J4.3 – DWR Flood Management Office - Rodent Abatement Program Appendix J5.1 – ARFCD Security Plan
Appendix J5.2 – City of Sacramento Levee Security Plan
Appendix J6.1 – ARFCD Flood Safety Plan
Appendix J6.2 – Sacramento County Emergency Operations Plan Appendix J6.3 – City of Sacramento Comprehensive Flood Management Plan Appendix J6.4 – City of Sacramento Levee Patrol Standard Operating Procedure Appendix J7 – Post Earthquake Remediation Plan – Kleinfelder

ACRONYMS AND ABBREVIATIONS
AEP annual exceedance probability
ARCF American River Common Features
ARFCD American River Flood Control District
ARSL American River South Levee
cfs cubic feet per second
CPT Cone Penetration Test
CVFPB Central Valley Flood Protection Board
DMM Deep Mix Method
DWR California Department of Water Resources
DWSE Design Water Surface Elevation
EC Engineer Circular
EM Engineer Manual
ETL Engineer Technical Letter
FEMA Federal Emergency Management Agency
GEI GEI Consultants, Inc.

H:V horizontal-to-vertical ratio
HTOL Hydraulic Top of Levee
JFP Joint Federal Project
LF linear feet
LM Levee Mile
LMA Local Maintaining Agency
MA9 Maintenance Area 9
MBK MBK Engineers
MTOL Minimum Top of Levee
n.d. Not Dated
NIMS National Incident Management System
NLD National Levee Database
O&M operation and maintenance
pcf pounds per cubic foot
PIR Problem Identification Report
RD Reclamation District
RM River Mile
SAFCA Sacramento Area Flood Control Agency
SB Senate Bill
SB Wall Soil Bentonite Wall
SC Soil Cement
SCB Soil Cement Bentonite
SCCB Slag Cement-Cement Bentonite
SOP Standard Operating Procedure
SPFC State Plan of Flood Control
SPK Sacramento District (USACE)
WPRR Western Pacific Railroad
ULDC Urban Levee Design Criteria
ULOP Urban Level of Flood Protection
UPRR Union Pacific Railroad
USACE U.S. Army Corps of Engineers
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USACE RIP USACE Rehabilitation and Inspection Program
WSE water surface elevation
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1 1.0 INTRODUCTION
In 2008, the California Legislature passed Central Valley Flood Protection Act (Senate Bill (SB) 5), which requires all cities and counties within the Sacramento-San Joaquin Valley to make findings related to an urban level of flood protection for urban and urbanizing lands within a flood hazard zone. The bill defined “urban level of flood protection” as the level of flood protection necessary to withstand flooding that has a 1-in-200 chance of occurring in any given year (annual exceedance probability or AEP) using criteria consistent with, or developed by, the California Department of Water Resources (DWR). The Urban Level of Flood Protection Criteria (ULOP Criteria) implementation guidance, issued by the State in November 2013, requires that these findings be based on substantial evidence in the record.

This document and its associated appendices provide substantial evidence that the levee system protecting a portion of the urban area in Sacramento County protected by the American River south levee and Sacramento River east levee meets ULOP Criteria for a 1-in-200 AEP1 in accordance with the State of California’s Urban Levee Design Criteria (ULDC), issued in May 2012.

ULOP Criteria (EVD-1) requires that the substantial evidence include, at a minimum, “a report prepared by a Professional Civil Engineer registered in California to document the data and analyses for demonstrating the property, development project, or subdivision has an urban level of flood protection.” The ULOP Criteria indicates that the Engineer’s Report should include the following:
 A list of the flood management facilities, including, but not limited to, State Plan of Flood Control (SPFC) facilities;
 The location of the flood management facilities;
 The entities that operate and maintain the flood management facilities; and  A list of, and consideration of, reports, evaluations, inspections, and performance history of the flood management facilities.

This Engineer’s Report relies on several other documents, reports, analyses, and evaluations, some of which are listed in the bibliography at the end of this report. This report does not, nor is it intended to, present all the evidence in the record. Instead, this Engineer’s Report and its bibliography are limited to presenting the substantial evidence required to demonstrate that an urban level of flood protection exists.

Documents that evaluate and describe the condition and performance of the facilities that are not included in the bibliography are incorporated by reference and have been provided separately. If the evaluation does not explicitly meet the criteria an exception has been written and is included in the supporting documentation provided in the Appendix.

The ULOP Criteria also requires a report by an Independent Panel of Experts (IPE Panel) on the review of this Engineer’s Report. The Panel’s report and responses to the Panel’s comments are provided separately in Appendix B.

In October 2024, the City of Sacramento (City) adopted an Adequate Progress Finding (APF) for the six levee systems protecting the Sacramento metropolitan area within their jurisdictions. This included the American River South Levee System. The APF was based on a report prepared by SAFCA titled, Urban 1 The 1-in-200 AEP flood is also referred to as the 200-year flood.

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AMERICAN RIVER SOUTH LEVEE SYSTEM
2 Level of Flood Protection Annual Report, dated August 2024. In December 2024, the County of Sacramento (County) adopted an APF for the same system using the same SAFCA report referenced previously. This report presented substantial evidence that once the planned improvements identified in the report were completed, the structural flood control facilities protecting the urban areas of the City and County from flooding would be able to withstand flooding from a 1-in-200 AEP flood event, in accordance with the State of California’s ULDC, issued in May 2012.

Since the American River South Levee System does not require structural improvements (excluding Beach Lake south levee, which is not included in this package and does require structural improvements), and non-structural actions have been completed, this Engineer’s Report certifies the American River South Levee System as meeting ULDC and the 1-in-200 AEP urban level of flood protection. This Engineer’s Report presents the substantial evidence needed to support this certification.

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3 2.0 DESCRIPTION OF AMERICAN RIVER SOUTH LEVEE
SYSTEM
The American River South Levee System is comprised of 3 levees: American River south (left) levee, Sacramento River east (left) levee, and Beach Lake north (right) levee (Figure 1). Beach Lake north (right) levee will not be evaluated as part of this report. Right and left designations are defined as which side the levee is observed on when looking downstream. Figures 2a and 2b provide stationing and general levee features for the American River south levee and Sacramento River east levee, respectively. The total length of the levee system is approximately 26.5 miles.

The American River south levee, as defined in the O&M manual (USACE, 2016a), terminates at the Mayhew Drain closure structure, the geotechnical evaluation of this segment was provided by MBK (MBK, 2025e). Additionally, the American River south levee extending upstream of the Mayhew Drain closure structure was evaluated by MBK but is not considered part of the Federal Levee System.

The Mayhew Drain, which feeds into the Mayhew Drain closure structure, was constructed with levees on either side. These levees and canal are designed to convey internal drainage into the American River.

Kleinfelder provided the geotechnical evaluation of the Mayhew Drain levees for the purpose of internal drainage functionality (Kleinfelder, 2025), not for ULDC, and is included in MBK’s evaluations.

A detailed description of each levee is included under the Physical Description below. The American River south levee geotechnical evaluation was performed by MBK Engineers (Station 1000+00 to 1635+50). The Sacramento River east levee’s geotechnical evaluation was performed by GEI (GEI, 2025) (Stations 1080+00 to 1150+00, 1185+00 to 1206+00, 1285+75 to 1418+00, and 1534+40 to 1640+00), and Kleinfelder (Stations 1000+00 to 1080+00, 1150+00 to 1185+00, 1206+00 to 1285+75, 1418+00 to 1534+40, and 1640+00 to 1770+00).

3.0 PHYSICAL DESCRIPTION

AMERICAN RIVER SOUTH (LEFT) LEVEE
The American River south levee was originally constructed by local land owners in the late 1800s and early 1900s and was subsequently improved by USACE in the mid-1900s as part of the Sacramento River Flood Control Project, authorized in 1917, and the American River Levee Project. In the early 2000s, USACE installed significant lengths of cutoff wall in the levee as part of the American River Watershed Common Features Project. The downstream portion of the levee was constructed prior to construction of the Folsom Dam. The American River south levee extends from the confluence of the Sacramento and American Rivers (Station 1000+00) upstream 10.5 miles to the Mayhew Drain closure structure (Station 1556+00). ARCFD maintains the American River south levee. The American River south levee continues upstream of the Mayhew Drain closure structure to high ground, Station 1635+50, which is the termination point used for this evaluation. Mayhew Drain, which continues towards the river from Folsom Boulevard, crosses through the closure structure. Cutoff walls are present for almost the entire length of levee; a gap is present for approximately 1 mile near the City’s landfill where high ground extends inland of the landside slope.

The levee is crossed by several transportation routes: Interstate 5, Del Paso Boulevard, Highway 160, Capital City Freeway (Interstate 80 Business Route), UPRR, H Street, Guy West Bridge (pedestrian walkway), Howe Avenue, and Watt Avenue.

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4 Downstream of Capital City Freeway, land use on the landside of the levee consists predominantly of commercial and industrial development. Upstream of Capital City Freeway, landside use is predominately urban and suburban development with occasional open lands associated with parks and schools. There is no waterside development.

SACRAMENTO RIVER EAST (LEFT) LEVEE (SREL)
The Sacramento River east levee was built and improved by local forces and the USACE from the late 1800s to mid-1900s. The portion of the Sacramento River east levee included in this levee system extends from the confluence of the American and Sacramento Rivers (Station 1000+00) and extends downstream

14.6 miles to the town of Freeport, specifically where the levee meets the Beach Lake north levee near Cliff’s Marina (Station 1770+00).

The Sacramento River east levee continues downstream to its terminus at the Sacramento San Joaquin Delta. The downstream limit of the Sacramento River east levee defined in this ULDC Report represents the transition from urban to non-urban levee designation.

Following the 1986 flood event, it became evident that significant levee improvements were needed to prevent seepage and reduce flood risk. Since the 1986 flood, several efforts from 1990-2006 were undertaken by the USACE, State of California, and SAFCA to construct levee improvements. As a result of these improvements, a cutoff wall was constructed approximately 12 miles along this portion of the Sacramento River east levee. A drained seepage berm is located between Pioneer Reservoir and the levee toe. Relief wells, six at Pioneer Reservoir and ten at Sump 132, were installed in 2006 and 2003, respectively. There are two major sections of retaining/floodwall along the river side of the levee in the downtown area: an older wall which is in part a seawall between I-Street and the Tower Bridge, and a newer wall of sheet pile and concrete retaining wall between Tower Bridge and the southern end of the waterfront promenade, all between Station 1040+50 and 1082+40. The floodwall north of Tower Bridge has numerous gaps for waterside pedestrian access that include stoplog closures. For the majority of this reach of the Sacramento River east levee there is a railroad present either on the crown or along the landside of the levee, and a bike trail on, or adjacent to, the levee. Multiple USACE contracts have been completed between 2019 and 2025 along the Sacramento River east levee to mitigate underseepage and lingering through seepage issues, geometry, reduce vegetation, and address waterside erosion. This work included construction of multiple deep seepage cutoff walls, stability and seepage berms, removal of vegetation on the levee, addition of waterside riprap, removal and/or relocation of encroachments and penetrations, and collection of additional easements and property rights. Additionally, Interstate 5 is adjacent to the landside of the levee from downtown to the Little Pocket area. At the downstream end, a removable stoplog structure provides freeboard in the Cliff’s Marina parking lot. Significant urban development is present along the landside of the entire levee. In the downtown and Miller Park area, there is waterside commercial development.

Multiple agencies maintain the Sacramento River east levee. ARFCD maintains the most upstream portion of the levee from Station 1000+00 to 1020+85 near the Sacramento River water intake facility. The City of Sacramento maintains the levee from Station 1020+85 to 1215+95 which is through the downtown area to approximately Sutterville Road; and DWR Maintenance Area 9 (MA9) maintains the levee from Station 1215+95, downstream to Station 1770+00, i.e., approximately Sutterville Road to Beach Lake North Levee, downstream of the Town of Freeport.

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5 4.0 PERFORMANCE HISTORY

AMERICAN RIVER SOUTH LEVEE
For the American River south levee, past performance issues include erosion, which is now largely mitigated through waterside bank protection largely consisting of rock rip rap placed over time, and through and underseepage and instability, which is now mitigated through installation of cutoff walls.

The performance history assessment for the American River south levee is based on review of available records and information at the USGS American River at Fair Oaks gage (11446500) and CA DWR American River at H Street gage (A0714). Per the California Nevada River Forecast Center, the H Street gage has the following flood thresholds2 all referenced to the North American Vertical Datum of 1988 (NAVD88):
• Action/Monitor Gage height 39.0 feet
• Minor Flood Gage height 42.0 feet
• Moderate Flood Gage height 45.7 feet
• Major Flood Gage height 46.7 feet
The H Street gage record is readily available only back to 1983, whereas the Fair Oaks gage record goes back to 1905. A relationship was developed between the flow at Fair Oaks and the gage height at H Street to estimate the number of occurrences of the flood thresholds being equaled or exceeded. The number of occurrences since the completion of Folsom Dam in 1955 and 2024 are summarized in Table 1.

Table 1. Estimated Number of Occurrences of H Street Annual Peak Gage Height Exceeding Flood Thresholds, 1955-2024
Flood Threshold
H Street
Gage Height
(feet)
Estimated
Corresponding Fair
Oaks flow (cfs)
Estimated Flow
Frequency1
Number of years
equaled or
exceeded
Action/Monitor 39 88,000 20-year 5
Minor Flood 42 120,000 > 200-year 1
Moderate Flood 45.7 >160,000 Between 200-year
and 500-year
0 Major Flood 46.7 >170,000 0
Note: 1 Based on flow frequency curve for Folsom Dam outflow.

SACRAMENTO RIVER EAST LEVEE
For Sacramento River east levee, the levee has experienced significant past performance issues over its lifetime primarily related to seepage and erosion. Following the 1986 flood, shallow cutoff walls were constructed in the early 1990s by USACE along approximately 11.5 miles of the levee system to address through seepage. Since that time subsequent erosion evaluation reports, prepared by USACE, have occurred every year from 19952000, in 2006, and in 2017. Flood fighting occurred within Sump 132 after the development of boils in 1986, 1997, and 2003, and rip rap was placed over a geotextile fabric in front of the intake apron after boils re-occurred in 1997. A seepage cutoff wall and relief wells on both sides of the channel were constructed by SAFCA in 2003. Other locations of underseepage and lingering through seepage issues were mitigated through construction of berms, relief wells at Pioneer Reservoir, and slurry cutoff walls in the early 2000’s through 2024.
2 https://www.cnrfc.noaa.gov/graphicalRVF.php?id=SAMC1
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6 Erosion occurred every year between 1995-1998. Waterside erosion sites encompassing nearly 11 miles were identified by USACE in 2014. Repairs have been under construction beginning in 2022 with anticipated completion expected in 2025 and consist of placement of rock rip rap.

The performance history assessment of the Sacramento River east levee is based on review of available gage data from the DWR Sacramento River at I Street gage (A02100) and the USGS Sacramento River at Freeport gage (11447650). Per the California Nevada River Forecast Center, the I Street gage has the following flood thresholds3 all referenced to the NAVD88:
• Action/Monitor Gage height 27.5 feet
• Minor Flood Gage height 33.5 feet
• Moderate Flood Gage height 35.4 feet
• Major Flood Gage height 36.4 feet
The evaluation looked at the period since the completion of Oroville Dam, the last major reservoir in the Sacramento River watershed, in 1968, a total of 57 years. The I Street gage has readily available data in the DWR Water Data Library starting in 1984. The relationship between the stages at the I Street gage and the Freeport gage were used to estimate the annual peak stages at I Street to complete the record for the evaluation period. The estimated number of occurrences in which the various flood thresholds at I Street were equaled or exceeded are summarized in Table 2.

Table 2. Estimated Number of Occurrences of I Street Annual Peak Gage Height Exceeding Flood Thresholds, 1968-2024 (57 years) Flood Threshold
I Street
Gage Height
(feet)
Number of years
equaled or exceeded
Action/Monitor 27.5 20
Minor Flood 33.5 2
Moderate Flood 35.4 0
Major Flood 36.4 0

5.0 EVALUATION OF AMERICAN RIVER SOUTH LEVEE
SYSTEM
The ULDC requires analysis under the 20 categories listed below. SAFCA’s certification team evaluated the American River South Levee System for compliance with each of the 20 ULDC categories. The evaluations are summarized in the following report subsections, and detailed documentation of the analyses are provided as appendices to this report.

3 https://www.cnrfc.noaa.gov/graphicalRVF.php?id=SACC1
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7 ULDC Category ULDC Category

7.1 Design Water Surface Elevation 7.11 Right-of-Way

7.2 Minimum Top of Levee 7.12
Encroachments (Excluding
Penetrations, Closure Structures,
and Levee Vegetation)

7.3 Soil Sampling, Testing, and
Logging 7.13 Penetrations

7.4 Slope Stability for Intermittently
Loaded Levees 7.14 Floodwalls, Retaining Walls, and Closure Structures

7.5 Underseepage for Intermittently
Loaded Levees 7.15 Animal Burrows

7.6 Frequently Loaded Levees 7.16 Levee Vegetation

7.7 Seismic Vulnerability 7.17 Wind Setup and Wave Runup

7.8 Levee Geometry 7.18 Security

7.9 Interfaces and Transitions 7.19 Sea Level Rise

7.10 Erosion 7.20 Emergency Actions
ULDC 7.1: DESIGN WATER SURFACE ELEVATION
The ULDC Design Water Surface Elevation (DWSE) is the 1-in-200 AEP water surface elevation (WSE) used to design and evaluate levees and floodwalls for the purposes of providing an urban level of flood protection.

The ULDC offers two options for determination of the DWSE: 1) the Federal Emergency Management Agency (FEMA) approach, and 2) the USACE approach. The evaluation for the American River South Levee System conforms to the FEMA approach based on available data and employing deterministic methods. In accordance with the ULDC, debris loading on bridge piers was included in the hydraulic analysis. The ULDC also requires adjustments for sea level rise and superelevation. Sea level rise was incorporated into the modeling downstream boundary conditions and there are four locations along the American River South Levee System subject to superelevation – American River (Station 1362+00 to 1340+00, Station 1257+00 to 1250+00, and Station 1150+00 to 1125+00) and Sacramento River (Station 1660+00 to 1680+00). Climate change is considered optional in the ULDC and was not adjusted for in this modeling due to lack of guidance for implementation. Hydrology modeling was provided from the Central Valley Hydrology Study (CVHS, 2015) and hydraulics models were developed by MBK based on the Sacramento River Watershed HEC-RAS models that were originally developed for the DWR Central Valley Floodplain Evaluation and Delineation project. A detailed description of the determination of the DWSE is found in URBAN LEVEL OF FLOOD PROTECTION ENGINEER’S REPORT

AMERICAN RIVER SOUTH LEVEE SYSTEM
8 Technical Memorandum, American River South Levee System - Determination of the Urban Levee Design Criteria Design Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee (MBK, 2025d).

An additional elevation required by the ULDC is the hydraulic top of levee (HTOL), which is defined as the lower of the DWSE plus 3 feet or the median 500-year WSE.

The computed DWSEs for the American River South Levee System are provided in Appendix C.

The American River South Levee System meets ULDC 7.1 for development of the DWSE.

ULDC 7.2: MINIMUM TOP OF LEVEE
The Minimum Top of Levee (MTOL) is the required minimum elevation for the physical top of levee to provide a reasonable assurance of containing the DWSE and is defined as the higher of the DWSE plus 3 feet or the DWSE plus wind setup and wave runup. The determination of the MTOL is described in (MBK, 2025d) and provided in Appendix C.

Wind setup and wave runup were computed by Mead & Hunt (Mead & Hunt, 2024) and are discussed below in ULDC 7.17. There are no locations along the American River south levee where the combined wind setup and wave runup is greater than 3 feet. A majority of the Sacramento River east levee has a combined wind setup and wave runup less than 3 feet except for the downstream segment between Station 1665+00 and 1770+00 which has a combined wind setup and wave runup of 3.5 feet. Therefore, the MTOL is the DWSE plus 3 feet for American River and the upstream portion of the Sacramento River and the MTOL is the DWSE plus 3.5 feet for the downstream portion of the Sacramento River. Figures 12 and 13 in Technical Memorandum, American River South Levee System - Determination of the Urban Levee Design Criteria Design Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee (MBK, 2025d) provides profiles showing the computed MTOL and actual top of levee profile. The levee height exceeds the MTOL in all locations except for a short segment along the Sacramento River near Station 1050+00. At this location, the O&M manual and flood fight plan have instructions to add muscle wall and flood fight materials as needed to close the gap in the floodwall system. Due to the documentation and materials outlined in this plan, and acknowledgment from the LMA responsible to perform these duties, this segment meets with exception and criteria are met.

The American River South Levee System meets ULDC 7.2 for MTOL, by exception.

ULDC 7.3: SOIL SAMPLING, TESTING, AND LOGGING
ULDC 7.3 requires soil sampling, testing, and logging, as per standard procedures prescribed in guidance documents, including the USACE Sacramento District (SPK) Standard Operating Procedure 3 Geotechnical Levee Practice (SOP-3) (USACE, 2022) and DWR Division of Flood Management’s Soil and Rock Logging, Classification, Description and Presentation Manual (DWR, 2009). This includes an evaluation of soil exploration quantity and location as outlined in the SPK SOP-3. Based on this document, explorations for a feasibility study should be obtained at a spacing of approximately 1,000 feet along the levee crest and at a spacing of approximately 500 feet along the waterside toe, levee crown, landside toe for preconstruction and design studies. The SPK SOP denotes “waterside borings may be omitted if site conditions prevent access, such as waterside channels immediately adjacent to the levee, and these explorations may be shifted to the landside.” The SPK SOP-3 also recommends a thorough evaluation of URBAN LEVEL OF FLOOD PROTECTION ENGINEER’S REPORT

AMERICAN RIVER SOUTH LEVEE SYSTEM
9 existing information, as available, including construction documents, improvements, performance history, existing subsurface information, and regional and local geomorphology. The standard also recommends the use of cone penetrometers (CPTs) and geophysics to supplement borings, where appropriate.

AMERICAN RIVER SOUTH LEVEE
MBK (2025e) and Kleinfelder (2025b) have reviewed the geotechnical data available for the American River south levee and Mayhew Drain levees, respectively. A review of available explorations and lab testing indicates waterside and field explorations are not present, however, SPK SOP-3, allows for a reduction in waterside explorations with justification. The reduction in waterside explorations have been compensated through additional landside explorations and use of and evaluation of full time trench logging of the various seepage cutoff walls, review of documented past performance and historical records, review of geologic and geomorphological mapping, and visual observation of the waterside embankment. Seepage and stability analysis continued stratigraphy into the channel and removed the fine grained waterside blanket to account for future scour. Additionally, USACE determined (USACE, 2014) that the American River south levee meets USACE design standards for stability and seepage. These analyses were based on soil sampling, testing and logging performed by USACE. This information is considered sufficient to meet ULDC 7.3.

Therefore, the American River south levee meets the requirements for ULDC 7.3 Soil Sampling, Testing and Logging.

SACRAMENTO RIVER EAST LEVEE
Soil exploration information for the Sacramento River east levee is contained in the reports prepared by GEI (2025) and Kleinfelder (2025) provided in Appendices D and E, respectively. The exploration spacing described above was generally met for this levee with the exception of borings at the waterside toe due to the presence of heavy vegetation and the proximity of the levee to the water channel. Soil sampling, testing, and logging were generally performed following the guidance outlined above. The soil explorations that were obtained were used in combination with geology and geomorphology, geophysical resistivity surveys, past performance information, historical records, and construction records to provide an adequate assessment of the subsurface conditions as outlined in the SPK SOP-03 for levee evaluations.

SPK SOP-03 allows for a reduction in waterside explorations if access is prevented. The waterside explorations may be shifted landward to collect additional data. The geotechnical evaluation reviewed all available explorations including additional field data consisting of full time trench logging of the various seepage cutoff walls, review of documented past performance and historical records, review of geologic and geomorphological mapping, and visual observation of the waterside embankment. This information in combination with the existing explorations is considered sufficient to meet ULDC 7.3.

Therefore, the Sacramento River east levee meets the requirements for ULDC 7.3 Soil Sampling, Testing and Logging.

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10 ULDC 7.4: SLOPE STABILITY FOR INTERMITTENTLY LOADED
LEVEES
This section describes the levee documentation and general requirements for ULDC 7.4 Slope Stability for Intermittently Loaded Levees. An intermittently loaded levee is defined as “a levee that does not experience a WSE of one foot or higher above the elevation of the levee toe at least once a day for more than 36 days per year on average.”
ULDC 7.4.1 requires a minimum factor of safety of 1.4 for landside slope stability under steady state seepage conditions, based on the DWSE, for failure surfaces that intersect the levee crown and are greater than a few feet deep in the levee slope. It also requires a minimum factor of safety of 1.2, based on the Hydraulic Top of Levee (HTOL)4, for failure surfaces that intersect the levee crown and are greater than a few feet deep in the levee slope. ULDC 7.4.1 evaluates the phreatic surface related to through seepage and erodibility of embankment and near surface blanket soils. ULDC 7.4.2 requires a minimum factor of safety of 1.0 to 1.2 for waterside slope stability during rapid drawdown conditions for the DWSE, depending on how long the embankment is saturated, with the higher factor of safety used for events of a longer duration. An intermittently loaded levee is defined as “a levee that does not experience a WSE of one foot or higher above the elevation of the levee toe at least once a day for more than 36 days per year on average.”
The American River south levee and Sacramento River east levee are considered intermittently loaded levees.

AMERICAN RIVER SOUTH LEVEE
MBK (2025e) and Kleinfelder (2025b) have reviewed the existing slope stability analyses, performed by various consultants, along the American River south levee and Mayhew Drain levees, respectively, and found them to meet slope stability criteria using the 200-year DWSE and HTOL water levels. Levee crest profiles and levee cross sections used previously for slope stability analysis were reviewed and found to be consistent with recent surveys (Psomas, 2025) and reevaluation at critical sections was not necessary.

Kleinfelder and MBK also compared the DWSE used in prior analysis with the current 200-year DWSE and determined that the WSE was equal to or lower than values used in prior evaluations. MBK summarized the analysis results performed by others, which cover the levee segments reviewed by MBK and relied upon a Statement of Performance provided by USACE (USACE, 2014) as to the adequacy of the completed construction projects. In addition, review of available historic performance and slope stability analysis referenced in the due diligence reports prepared by Kleinfelder and MBK (Appendices E and F, respectively) meet slope stability criteria.

Therefore, the American River south levee meets the requirements for ULDC 7.4 Slope Stability for Intermittently Loaded Levees.
4 The hydraulic top of levee is defined by ULDC as the lower of the median 200-year WSE plus 3 feet or the median 500-year WSE. The HTOL was developed using the approach described in ULDC 7.1 URBAN LEVEL OF FLOOD PROTECTION ENGINEER’S REPORT

AMERICAN RIVER SOUTH LEVEE SYSTEM
11 SACRAMENTO RIVER EAST LEVEE
The Sacramento River east levee between the American River south levee and Beach Lake north levee was evaluated by GEI (2025) and Kleinfelder (2025b). For these segments, prior engineering analyses performed by Kleinfelder, GEI, and other consultants were reviewed to confirm the existing and/or remediated levee configurations meet ULDC and USACE minimum factor of safety requirements for slope stability. These analyses were reviewed by GEI and Kleinfelder to compare the prior evaluated WSE to the revised 200-year WSE prepared for this evaluation (Appendix C). A summary of prior slope stability analyses is described in the due diligence reports prepared by GEI and Kleinfelder which includes a review of past performance (Appendices D and E). GEI and Kleinfelder concluded the analyses were performed at critical sections, the evaluated WSE was higher than the new 200-year WSE, and the modeled improvements were the same or more conservative than the constructed features, which met analysis criteria. These results provide the condition evaluated, water surface designation, and the calculated stability factor of safety. Kleinfelder’s slope stability model for Station 1072+00 through the I-5 depressed section at N Street only meets criteria if the Caltrans dewatering system that is not part of the flood protection system is operating. As a result, Station 1072+00 meets ULDC criteria through exception.

Therefore, the Sacramento River east levee meets the requirements for ULDC 7.4 Slope Stability for Intermittently Loaded Levees through exception.

ULDC 7.5: UNDERSEEPAGE FOR INTERMITTENTLY LOADED
LEVEES
This section describes the levee documentation and general requirements for ULDC 7.5 Underseepage for Intermittently Loaded Levees. An intermittently loaded levee is defined as “a levee that does not experience a WSE of one foot or higher above the elevation of the levee toe at least once a day for more than 36 days per year on average.”
“Levee underseepage criteria for intermittently loaded levees are as follows:
• The underseepage exit gradient for levees is required to be 0.5 or less at the landside levee toe using a steady-state seepage analysis for a water surface set at the DWSE. For levees with a landside blanket layer with a saturated unit weight less than 112 pounds per cubic foot (pcf), a minimum factor of safety for underseepage of 1.6 is required at the landside levee toe. • The underseepage exit gradient is required to be 0.8 or less at the toe of a seepage berm less than 300 feet wide using steady-state seepage analysis for a water surface set at the DWSE. If the saturated unit weight of the blanket layer is less than 112 pcf, a minimum factor of safety for underseepage of 1.0 is required at the toe of the seepage berm.”

AMERICAN RIVER SOUTH LEVEE
MBK (2025e) and Kleinfelder (2025b) have reviewed the current seepage evaluations for the American River south levee and Mayhew Drain levees, respectively, and found them to meet seepage criteria using the 200-year DWSE and HTOL water levels. Levee crest profiles and levee cross sections used previously for seepage analyses are consistent with recent surveys (Psomas, 2025) and reevaluation of critical sections is not necessary. MBK summarized the analysis results performed by others, which cover the URBAN LEVEL OF FLOOD PROTECTION ENGINEER’S REPORT

AMERICAN RIVER SOUTH LEVEE SYSTEM
12 levee segments reviewed by MBK and relied upon a Statement of Performance provided by USACE (USACE, 2014) as to the adequacy of the completed construction projects. In addition, review of historic performance and seepage analyses referenced in the due diligence reports prepared by Kleinfelder and MBK (Appendices E and F, respectively) meet underseepage requirements.

Therefore, the American River south levee meets the requirements for ULDC 7.5 Underseepage for Intermittently Loaded Levees.

SACRAMENTO RIVER EAST LEVEE
The Sacramento River east levee between the American River south levee and Beach Lake north levee was evaluated by GEI (2025) and Kleinfelder (2025b). For these segments, prior engineering analyses by Kleinfelder, GEI, and other consultants were reviewed to confirm the existing and/or remediated levee configurations meet ULDC and USACE maximum seepage gradient criteria. These analyses were reviewed to compare the prior evaluated WSE to the revised 200-year WSE prepared for this evaluation (Appendix C). A summary of seepage analyses is described in the due diligence reports prepared by GEI and Kleinfelder. GEI and Kleinfelder concluded the analyses were performed at critical sections, the evaluated WSE was higher than the new 200-year WSE, and the modeled improvements were the same or more conservative than the constructed features, which met analysis criteria. These results provide the condition evaluated, water surface designation, and the calculated seepage gradients. In addition, review of historic performance and seepage analyses referenced in the due diligence reports prepared by GEI and Kleinfelder (Appendices D and E, respectively) meet underseepage requirements. Kleinfelder’s seepage model for Station 1072+00 through the I-5 depressed section at N Street only meets criteria if the Caltrans dewatering system that is not part of the flood protection system is operating. As a result, Station 1072+00 meets ULDC criteria through exception.

Therefore, the Sacramento River east levee meets the requirements for ULDC 7.5 Underseepage for Intermittently Loaded Levees through exception.

ULDC 7.6: FREQUENTLY LOADED LEVEES
ULDC 7.6 clarifies that frequently loaded levees are subject to more stringent requirements. Frequently loaded levees are those levees that experience a WSE of 1 foot or higher above the elevation of the landside levee toe at least once a day for more than 36 days per year on average.

As part of the ULE Program, DWR determined that the American River South Levee System has intermittently loaded levees (URS, 2015b). The SAFCA certification team reviewed DWR’s conclusion and concurs. ULDC 7.6 for frequently loaded levees is not applicable.

ULDC 7.7: SEISMIC VULNERABILITY
ULDC 7.7 requires an analysis of seismic vulnerability of the levee system for the 200-year return period ground motions. ULDC 7.7.1 indicates that if seismic damage from the 200-year return period ground motion is expected, a post-earthquake remediation plan is required as part of a flood safety plan developed in coordination with pertinent local, State, and Federal agencies.

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13 A seismic vulnerability analysis was performed by Kleinfelder to evaluate liquefaction potential and pseudo static stability. This evaluation is summarized in Kleinfelder’s Seismic Performance Summary Report included as an appendix to the Due Diligence report (Kleinfelder, 2025b) provided in Appendix E.

This evaluation determined that three segments along the American River south levee and nine segments along the Sacramento River east levee have liquefiable layers and/or seismic stability concerns which categorize these segments as High Seismic Vulnerability. These segments are summarized in Table 3 below and are consistent with analyses that were performed previously in 2015 (URS, 2015). The other levee segments not included in Table 3 were categorized as low or moderate vulnerability.

Table 3: Summary of High Vulnerability Levee Segments
Start Station End Station Seismic Vulnerability
American River South Levee
1000+00 1135+00 High
1195+00 1335+86 High
1381+93 1431+25 High
Sacramento River East Levee
1000+00 1019+00 High
1019+00 1086+00 High
1086+00 1178+00 High
1178+00 1214+00 High
1214+00 1245+00 High
1245+00 1286+00 High
1286+00 1425+00 High
1425+00 1671+00 High
1707+50 1770+00 High
Due to these findings, a post-earthquake remediation plan is required for portions of the American River south levee and Sacramento River east levee. This plan has been prepared and is provided in Appendix J7.

Therefore, with inclusion of the Post Earthquake Remediation Plan, the American River South Levee System meet ULDC 7.7.

ULDC 7.8: LEVEE GEOMETRY
ULDC 7.8 requires that for new levees or levees with extensive reconstruction situated along major waterways, a minimum 20-foot-wide crown width for Major Streams (mainstreams) or 12-foot crown width for Minor Streams (tributaries to mainstream) and 3:1 horizontal-to-vertical ratio (H:V) waterside and landside slopes are required. Landside slopes can remain 2H:1V for existing levees with good performance. As outlined in the 1953 Memorandum of Understanding, the American River south levee and the Sacramento River east levee are considered major stream levees.

ULDC 7.8.1 allows levees wider than the minimum requirement to have steeper slopes if the minimum required dimensions would fit entirely within the actual levee, and if seepage and slope stability criteria are met (for both deep and shallow failure surfaces).

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14 ULDC 7.8.2 requires a patrol road along the crown of the levee for inspection, maintenance, and floodfighting. The patrol road must be designed, constructed, and maintained to provide “all-weather” support of maintenance and patrolling vehicles.

AMERICAN RIVER SOUTH LEVEE
The American River south levee is classified as major stream levee. The ULDC requires that existing levees have the following geometry (minimum theoretical prism):
• 2H:1V landside slope
• 20-foot-wide levee crown (major)
• 3H:1V waterside slope
Construction projects have modified the original levee including geometry corrections. These corrections are consistent with ULDC requirements and as-builts of these projects and recent survey data verify these criteria were met. Psomas obtained recent ground survey data (Psomas, 2025) to compare existing geometry to criteria. Cross sections are included in Appendix H. These cross sections were reviewed by MBK (2025e) and confirm the prior as-built cross sections still exist which indicate the American River south levee meets current geometry criteria.

Therefore, the American River south levee meets requirements for ULDC 7.8 Levee Geometry.

SACRAMENTO RIVER EAST LEVEE
The Sacramento River east levee is classified as a major stream levee. The ULDC requires that major stream levees have the following geometry (minimum theoretical prism):
• 2H:1V landside slope
• 20-foot-wide levee crown
• 3H:1V waterside slope
Construction projects have modified the original levee including geometry corrections. These corrections are consistent with ULDC geometry requirements and as-builts of these projects, including recent survey data, verify geometry meets criteria. Some locations indicate an overbuilt section exists with steeper levee slopes. However, due to the widened section and acceptable slope stability factors of safety, the cross sections meet criteria. Psomas obtained recent ground survey data (Psomas, 2025) to compare existing geometry to criteria. Cross sections are included in Appendix H. These cross sections were reviewed by GEI (2025) and Kleinfelder (2025b) along with stability analysis results and indicate the Sacramento River east levee meets current geometry criteria. Confirmation that the levee meets seepage and slope stability criteria was also performed.

Therefore, the Sacramento River east levee meets requirements for ULDC 7.8 Levee Geometry.

ULDC 7.9: INTERFACES AND TRANSITIONS
This section describes the levee documentation and general requirements for ULDC 7.9 Interfaces and Transitions.

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15 “The civil engineer must consider, evaluate, and explicitly design for interfaces and transitions between different types of levee sections and features along a levee system. Appropriate overlaps, transitions, and connections between features must be evaluated and designed to ensure that the levee system functions holistically, such that no levee reach is more susceptible to problems than an adjacent reach due to gaps in features, loading/demand concentrations, or other three-dimensional effects. Such interfaces, transitions, and connections commonly occur at the ends of seepage berms, seepage cutoff walls, revetments, and floodwalls.”
ULDC 7.9 highlights the need to ensure that the levee system functions holistically, such that no levee reach is more susceptible to problems than an adjacent reach, due to gaps in features, loading/demand concentrations, or other three-dimensional effects when designing interfaces, transitions, and connections that commonly occur at the ends of seepage berms, seepage cutoff walls, and revetments.

Boundary conditions at each of the intersections of the levee segments were evaluated to consider the most critical loading scenario with respect to underseepage and stability. These evaluations were performed by GEI, Kleinfelder, and MBK, with conclusions provided in the individual due diligence reports.

A summary of the transitions and interfaces present in this levee system are outlined below.

AMERICAN RIVER SOUTH LEVEE
A summary of the interface and transitions reviewed along the American River south levee are provided below. Additional documentation can be found in the due diligence report prepared by MBK (2025e) provided in Appendix F.
1) American River south levee Station 1000+00 tie-in with Sacramento River east levee Station 1000+00.
2) American River south levee transitions to high ground at the downstream side of the Sutter’s Landing near Station 1134+00. The surrounding high ground in this area is approximately 6 to 7 feet above the design WSE which continues adjacent to the City of Sacramento Landfill near Station 1157+00 extending to
near Station 1196+00 at the UPRR tracks. The surrounding high ground in this area is approximately a minimum of 6 feet above the design WSE and extends landward more than 500 feet. High ground is defined as a ground surface greater than 3 feet above the DWSE that extends landward for over 500 feet.
3) American River south levee tie-in on both sides of the Mayhew Drain closure structure at Station 1556+00. The levee embankments at this location were reconstructed to connect to the closure structure embankment.
4) American River south levee tie-in with high ground at the upstream termination point of 1635+50. This is the point where the maintained levee crest road ends. High ground at this location is approximately 8 feet above the design WSE.
5) There are multiple overlaps and transitions between cutoff walls that are too numerous to list.

MBK reviewed these locations and confirmed the cutoff wall windows were closed by overlapping existing walls a minimum of 15 feet.

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16 These overlaps and transitions are considered appropriate as discussed above for the American River south levee.

Therefore, the American River south levee meets requirements for ULDC 7.9 Interfaces and Transitions.

SACRAMENTO RIVER EAST LEVEE
A summary of the interface and transitions reviewed along the Sacramento River east levee are provided below. Additional documentation can be found in the due diligence reports prepared by GEI and Kleinfelder in Appendices D and E, respectively.
1) Station 1000+00 to 1080+00 – remediation within this reach consists of a seepage berm and seepage cutoff wall (SCB). Each of these was constructed with appropriate overlaps and transitions to the adjacent levee configuration and condition (Kleinfelder, 2025) 2) Station 1080+00 to 1150+00 – a variety of remediation repairs are present within this reach consisting of seepage berm, stability berms, seepage cutoff walls (SCB, jet grout and SCCB), and relief wells. Each of these was constructed with appropriate overlaps and transitions to the adjacent levee configuration and condition (GEI, 2025)
3) Station 1150+00 to 1185+00 – no transitions or overlaps are present (Kleinfelder, 2025) 4) Station 1185+00 to 1206+00 – this levee segment was remediated with multiple varying depth seepage cutoff walls (SCB and SB). Each of these was constructed with appropriate overlaps and transitions to the adjacent levee configuration and condition (GEI, 2025) 5) Station 1206+00 to 1285+75 – this levee segment was remediated with multiple varying depth seepage cutoff walls (SCB, SCB DMM, SC jet grout). Each of these was constructed with appropriate overlaps and transitions to the adjacent levee configuration and condition (Kleinfelder, 2025)
6) Station 1285+75 to 1418+00 – this levee segment was remediated with multiple varying depth seepage cutoff walls (SCB, DMM, SCCB, and SB). Each of these was constructed with appropriate overlaps and transitions to the adjacent levee configuration and condition (GEI, 2025) 7) Station 1418+00 to 1534+40 – this levee segment was remediated with multiple varying depth seepage cutoff walls (SCB, SCB DMM, SB, SCCB, and SC jet grout) and relief wells. Each of these was constructed with appropriate overlaps and transitions to the adjacent levee configuration and condition (Kleinfelder, 2025)
8) Station 1534+40 to 1640+00 – this levee segment was remediated with multiple varying depth seepage cutoff walls (SCB, DMM, SCCB, and SB). Each of these was constructed with appropriate overlaps and transitions to the adjacent levee configuration and condition (GEI, 2025) 9) Station 1640+00 to 1770+00 – a variety remediation is present within this reach consisting of curb wall, floodwall, stability berm, and varying depth seepage cutoff walls (SCB DMM). Each of these was constructed with appropriate overlaps and transitions to the adjacent levee configuration and condition (Kleinfelder, 2025)
10) Station 1770+00 to 1779+00 – tie into Beach Lake North Levee.

These overlaps and transitions are considered appropriate as discussed above for the Sacramento River east levee.

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17 Therefore, the Sacramento River east levee meets requirements for ULDC 7.9 Interfaces and Transitions.

ULDC 7.10: EROSION
Levees that pose an immediate erosional breaching hazard during either a flood or during normal flow conditions need to be repaired to meet ULDC. Similarly, levees that are likely to be significantly damaged during either a flood or normal flow condition should be protected with appropriate revetment. Erosion hazards are evaluated for the following conditions: 1) high-velocity flows coupled with erosive levee materials and/or poor hydraulic conditions; 2) large waves developed by wind over large, open bodies of water; and 3) boat wakes. MBK performed an evaluation of the levees and considered potential factors such as existing erosion, geomorphologic trends, streamflow velocity and inundation depths during high water, wind-wave shear stress, levee materials, encroachments and anomalies, bank protection, and vegetation. MBK Engineers performed a levee inspection to observe multiple topics related to Operation and Maintenance, including erosion on January 15, 2025 (MBK, 2025b). The velocities were calculated in the HEC-RAS model utilized to create the design WSE profiles (MBK, 2025d). Permissible velocities come from USACE EM 1110-2-1601 “Hydraulic Design of Flood Control Channel”.

USACE-led efforts to protect the waterside levee toe are currently underway as part of the Sacramento River Bank Protection Project and the American River Common Features Project. Erosion mitigation treatments along the bank will further reduce flood risk and provide additional embankment protection from erosion along the Sacramento River and Lower American River within the American River South Levee System

AMERICAN RIVER SOUTH LEVEE
The Lower American River is regulated by flows initially released from Folsom Dam (117,000 cfs) and conveyed downstream through Nimbus Dam. Tailwater conditions are governed by the confluence of the American and Sacramento Rivers. As a result, flow velocities along the Lower American River and impacts along the bank and waterside slope of the American River south levee are a concern at locations of the highest velocity. A majority of the maximum flow velocities are less than 2.5 fps with a few isolated maximum velocities near 4.7 fps for the modeled event. The calculated water velocities are equal or less than the maximum permissible velocities for coarse sand and silt clay. The floodway for the American River is narrow and significant waves are not expected to develop. Boat traffic is regulated at 5 mph and wake activity does not materially contribute to erosion activity. The embankment material, comprised of poorly graded sand to silty sand, sandy silt, silt, and clay, has a moderate susceptibility to erosion for the modeled velocities (MBK, 2025b); however, past performance issues along the Lower American River is the primary reason for the USACE-led erosion protection projects to be designed and constructed to withstand events that surpass ULDC conditions
The American River south levee meets ULDC 7.10.

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18 SACRAMENTO RIVER EAST LEVEE
The potential of erosion activity along the SREL can be attributed to higher flows during high-water events in the flood season, potential wind setup and wave runup due to longer fetch lengths, and waves due to boating activity all year long. Flood velocities along the SREL are below the threshold of concern and the maximum velocity was determined to be under 2.7 fps, with a majority under 2.5 fps, for the modeled event. The calculated water velocities are equal or less than the maximum permissible velocities for either coarse sand and silt clay. The embankment material, comprised of relatively clean sands, clayey sands, silts, and lenses of gravels, has low susceptibility to erosion for the modeled velocities. USACE-led projects that focus on providing protection below the levee embankment are underway to withstand events that surpass ULDC conditions.

The Sacramento River east levee meets ULDC 7.10.

ULDC 7.11: RIGHT-OF-WAY
As per ULDC, right-of-way criteria for levees and floodwalls in urban and urbanizing areas need to allow adequate room for maintenance, inspection, patrolling during high water, and flood-fighting; allow additional room to expand facilities in the future; and prohibit excavations and land modifications that would endanger the integrity of the levee or floodwall.

Specifically, the ULDC requires fee title or an easement for the entire levee prism extending to a minimum of 20 feet beyond the landside toe of the flood protection system for access and inspection. ULDC also allows for two alternatives where adjacent lands are developed: 1) rights for a minimum 10-foot-wide landside clear zone or 2) a 20-foot-wide landside visibility zone. Furthermore, waterward of the levee prism, where there is sufficient area to do so without resulting in the loss of sensitive riparian habitat, consideration should be given to acquiring a 15-foot-wide zone.

In addition to the minimums required by the ULDC for access and inspection, the ULDC recommends acquiring right-of-way that has a width equal to at least four times the levee height or 50 feet, whichever is greater, on the landside of the 20-foot clear zone for longer-term flood protection.

Lastly, the ULDC recommends that the city or county adopt restrictions on excavations within 200 to 400 feet, depending on the levee height.

As part of its levee improvement program, SAFCA has worked to acquire land associated with the levee embankment, O&M corridors, and/or other flood control features. These lands were subsequently, or will be, transferred to the Sacramento San Joaquin Drainage District (SSJDD). Residential development adjacent to a majority of the American River south urban levee system has limited the availability for a 20- foot fee title right-of-way landward of the levee. Wherever feasible, SAFCA acquired waterside rights and rights to the levee footprint. Figures provided in the Right of Way Plan in Appendix J1 show the right-ofway acquired in fee-title and easement right-of-way for the levees. The goal is to acquire long-term rights (i.e., fee-title or easement) in locations where there is not currently 20-feet at the landside toe. These locations are identified in the American River South Levee System Right-of-Way Plan (MBK, 2025f). In 2013, the City of Sacramento adopted a grading ordinance (Ordinance 2013-0020 Section 1; Ordinance 2013-0007 Section 1) outlined in Title 17, Division II, Article III (17.200.340 F zone - Setbacks) that restricts any grading activity within 50 feet of the levee. Sacramento County has adopted a similar ordinance found URBAN LEVEL OF FLOOD PROTECTION ENGINEER’S REPORT

AMERICAN RIVER SOUTH LEVEE SYSTEM
19 in Sacramento County Zoning Code Section 4.7.3 Development Standards, specifically for Lots Protected by Levees (Section 4.7.3.A) which restricts construction of structures to no closer than 25 feet from the landside levee toe.

In general, future waterside development is not allowed and landside development within 50 feet of the levee is limited per a local grading ordinance which also restricts construction of swimming pools. In 2013, the City of Sacramento adopted a grading ordinance (Ordinance 2013-0020 Section 1; Ordinance 2013- 0007 Section 1) outlined in Title 17, Division II, Article III (17.200.340 F zone - Setbacks) that restricts any grading activity within 50 feet of the levee. Sacramento County has adopted a similar ordinance found in Sacramento County Zoning Code Section 4.7.3 Development Standards, specifically for Lots Protected by Levees (Section 4.7.3.A) which restricts construction of structures to no closer than 25 feet from the landside levee toe. Where swimming pools are located in close proximity to the landside levee toe, the geotechnical engineering review has assessed the condition, and a discussion is provided in the supporting documentation included in Appendices D, E, and/or F. Additionally, DWR reviews the presence of pools at the landside levee toe as part of the fall and spring inspections.

AMERICAN RIVER SOUTH LEVEE
The American River south levee and O&M corridors are located within lands owned by SAFCA, the City of Sacramento, Sacramento County, the SSJDD, the railroad and private owners. In general, a significant portion of this levee segment does not have 10-foot clear zone or 20-foot landside visibility zone. Due to the lack of easement and/or visibility, in order to meet ULDC criteria, a Right of Way plan is required.

Where fee or easement is not present for the 20-foot landside corridor, a summary of the site conditions is provided in the Right of Way Plan in Appendix J1.

The American River south levee meets ULDC 7.11 by exception through a Right of Way Plan.

SACRAMENTO RIVER EAST LEVEE
The Sacramento River east levee and O&M corridors are located within lands owned by SAFCA, the City of Sacramento, Sacramento County, the SSJDD, the railroad, and private owners. In general, a significant portion of this levee segment does not have 10-foot clear zone or 20-foot landside visibility zone. Due to the lack of easement and/or visibility, in order to meet ULDC criteria, a Right of Way plan is required.

Where fee or easement is not present for the 20-foot landside corridor, a summary of the site conditions is provided in the Right of Way Plan in Appendix J1.

The Sacramento River east levee meets ULDC 7.11 by exception through a Right of Way Plan.

ULDC 7.12: ENCROACHMENTS
ULDC 7.12 requires an assessment of each existing encroachment, permitted or not, to determine the encroachment’s impact on the reliability of levee performance. The evaluation of encroachments considers the following: age, type, condition, performance history, impacts on the levee structural integrity, impacts on the hydraulic effect of the channel, and impacts on the O&M of the levee. An encroachment is defined as any obstruction or physical intrusion by construction of works or devices, planting or removal of vegetation, or by whatever means for any purpose (DWR, 2012).

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20 A summary of Encroachments along with the methodology used following USACE, ULDC, and CVFPB guidelines is included in Appendix I (Mead & Hunt, 2025b). Additionally, MBK Engineers performed site visits to observe general conditions related to Operation and Maintenance, including encroachments.

Observations from this visit are summarized in a letter provided in Appendix G (MBK, 2025b) and all observed encroachments were consistent with prior evaluations with none being considered high-risk.

There are over 1,500 encroachments summarized in Appendix I. None of these pose a risk to levee integrity or reliability of the levee to perform under the full loading condition up to the HTOL. No highrisk encroachments were identified within this levee system. It should be noted that the high number of encroachments is due to adjacent urban development in near proximity to the landside levee toe. A framework for an encroachment remediation plan is included in Appendix J2 to address the low and moderate risk items identified by being non-compliant and non-permitted, as required by ULDC. The land use agency will need to use this framework to create and adopt an encroachment remediation plan. The Land Use Agency (i.e. City or County) are required to create, adopt, and implement in order to be in compliance with ULOP.

Therefore, the American River South Levee System meets ULDC 7.12.

ULDC 7.13: PENETRATIONS
ULDC 7.13 requires a hazard assessment of each existing penetration, permitted or not, to determine the penetration’s impact on the reliability of levee performance. A penetration is defined as a manmade object that crosses through or under a levee or floodwall and has the potential to provide a preferential seepage path or hydraulic connection with the waterside. Typically, a penetration is a pipe or transportation structure, such as a roadway or rail line (DWR, 2012). If penetrations are considered highhazard, additional evaluation and action are required. For other existing penetrations that are not considered to be high-hazard, but have not been permitted, the City or County is required to have a remediation plan in place, or reference such a plan, for the entire length of levee that the finding is to cover.

A summary of Penetrations along with the methodology used is included in Appendix I (Mead & Hunt, 2025b).

There are over 280 penetrations summarized in Appendix I. A few of these require an exception due to pipeline inverts below the DWSE, joint type risks, age, missing permits, and/or lack of inspection data. At this time, none of these pose a risk to levee integrity or reliability of the levee to perform under the full loading condition up to the HTOL. No high-hazard penetrations were identified within this levee system.

An exception is needed where penetrations do not meet criteria, however, through engineering evaluation they are determined to be low risk and will be remediated with a plan allowed by ULDC, included in Appendix J3.

Therefore, the American River South Levee System meets ULDC 7.13 through exception.

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21 ULDC 7.14: FLOODWALLS, RETAINING WALLS, AND CLOSURE

STRUCTURES
This section describes the levee documentation and general requirements for ULDC 7.14 Floodwalls, Retaining Walls, and Closure Structures.
“Current USACE design guidance for special features such as floodwalls, retaining walls, and closure structures is to be followed. This information is included in EM 1110-2-1913, EM 1110-2-2502, EC 1110-2-6067, and ETL 1110-2-571. Because design considerations for floodwalls and closure structures are still evolving since the 2005 New Orleans flood, caution should be used when designing and assessing these structures. All global slope stability and embankment throughseepage and underseepage safety criteria requirements are applicable for floodwalls, retaining walls, and closure structures on levees.

For closure structures, the civil engineer needs to provide the following information: maintaining entity, levee mile, Global Positioning System coordinates, Board permit number (if applicable), structure details, length of time to close structure, location and type of materials for closure, structure dimensions, age, and performance history.

Closure structures need to be tested at least once a year before the flood season so that crews responsible for implementing the structures are familiar with their operation and to provide assurance that all parts are present and in working order.”

AMERICAN RIVER SOUTH LEVEE
There are no floodwalls, retaining walls, or closure structures used for flood control, however, there are retaining wall structures utilized as part of roadway bridge crossings. These features are discussed as part of ULDC 7.13 Penetrations, provided by others. It should be noted that the Mayhew Drain closure structure, is not an actual closure structure or feature that requires equipment and procedures to construct to protect an area during a high-water event. This is a series of pipes through an embankment which can be activated to close mechanically when needed.

Therefore, these structures on the American River south levee meet ULDC 7.14.

SACRAMENTO RIVER EAST LEVEE
Floodwalls are located at Station 1040+50 to 1082+40 (Kleinfelder, 2025) and between Station 1040+50 and 1082+40, and between Station 1766+00 and 1770+50 (Mead & Hunt, 2025b). A concrete retaining wall present between Station 1023+30 and 1024+70 and a sheet pile retaining wall is present between Station 1662+49 and 1668+75 (Kleinfelder, 2025b). Per Mead & Hunt’s report (2025b), 152 retaining walls were identified, many of which are short walls tied to residential properties and were evaluated as encroachments. The floodwall and larger retaining walls that required evaluation were found to be well maintained and in serviceable condition for their intended use (Mead & Hunt, 2025b).

Per Mead & Hunt’s report (2025b), closure structures are located along the Sacramento River east levee between Station 1056+30 and 1043+50 and between Station 1770+50 and 1772+50 at Cliff’s Marina.

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22 These closure structures were evaluated and found to be acceptable for their intended use (Mead & Hunt, 2025b).

Therefore, these structures on the Sacramento River east levee meet ULDC 7.14.

ULDC 7.15: ANIMAL BURROWS
Borrowing animals can present a significant threat to levee integrity and, therefore, proactive animal control and damage repair are required as part of levee maintenance.

American River Flood Control District (ARFCD), MA9, and the City of Sacramento follow rodent control and abatement programs (ARFCD, 2017; DWR, 2015; City, 2024a) to maintain constant observation and deterrence of burrowing animals which are present in the American River South Levee System. The rodent control and abatement program tracks active burrows as well as the monthly abatement activity. The LMAs are vigilant in inspecting for burrowing animals and reacting quickly to repair any damage to the levees. MBK Engineers performed site visits to observe general conditions related to Operation and Maintenance, including animal burrows, on December 15, 2023 and January 14, 2025. Observations from these visits are summarized in a letter provided in Appendix G (MBK, 2025b) and no indications of excessive burrowing rodent activity were observed during those inspections. Additionally, the USACE Routine Inspection Report (USACE, 2023) provided a review of animal control and rated the American River south levee and Sacramento River east levee down to Sutterville Road Acceptable and the Sacramento River east levee downstream of Sutterville Road Minimally Acceptable.

Therefore, the entire American River South Levee System meets ULDC 7.15.

ULDC 7.16: LEVEE VEGETATION
ULDC 7.16.1 requires an engineering inspection and evaluation to identify trees and other woody vegetation on the levee and within 15 feet of the levee toe that pose an unacceptable threat to the integrity of the levee. Those posing an unacceptable threat are to be removed; those not posing an unacceptable threat need not be removed. Non-hazardous vegetation is allowed to remain because they do not pose an unacceptable threat but must be trimmed and thinned for access and visibility. The USACE Inspection Report (USACE, 2023) provided a review of unwanted vegetation growth, erosion, and encroachments with unacceptable ratings in these categories for both the American River south levee and Sacramento River east levee. This information is not consistent with observations from MBK Engineers site visits to view general conditions related to Operation and Maintenance, including vegetation.

Observations and communication with LMA indicate vegetation has been resolved with recent clearing, trimming, and removal. Observations from this visit are summarized in a letter provided in Appendix G (MBK, 2025b).

Therefore, the entire American River South Levee System meets ULDC 7.16.

ULDC 7.17: WIND SETUP AND WAVE RUNUP
ULDC 7.17 requires a wind-wave analysis. The wind setup and wave runup distances must be computed and added to the median 200-year still WSE to determine the required elevation of the MTOL.

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23 Additionally, wind setup and wave runup must also be considered for analysis of erosion and overtopping impacts.

The formation and magnitude of wind-generated waves against shoreline structures is controlled by the physical conditions present on and near the shore such as slope and roughness of the structure, wind speed, and distance over which wind blows (fetch length). The Wind Wave Analysis determined the wind setup and the runup for the 2 percent exceedance wave (wave runup which is exceeded by 2 percent of waves on average). The analyses were performed at the location on the levees expected to generate the largest wind setup and wave runup.

AMERICAN RIVER SOUTH LEVEE
The American River south levee was evaluated for wind setup and wave runup with expected ranges of approximately 1.6 to 2.3 feet (Mead & Hunt, 2024). There is more than 3 feet of freeboard available along this levee.

The wind-wave analysis for the American River south levee meets the ULDC 7.17 requirements.

SACRAMENTO RIVER EAST LEVEE
The Sacramento River east levee was evaluated for wind setup and wave runup with expected ranges of approximately 1.0 to 2.5 feet between Station 1000+00 and 1665+00 and ranges of approximately 3.1 to

3.5 feet between Station 1665+00 and 1770+00 (Mead & Hunt, 2024). There is more than 3.5 feet of freeboard available along this levee.

The wind-wave analysis for the Sacramento River east levee meets the ULDC 7.17 requirements.

ULDC 7.18: SECURITY
ULDC 7.18 requires a security plan to protect urban and urbanizing area levee systems from acts of terrorism and other malicious or negligent acts. The security plan is to identify security personnel, responsibilities, resources, and measures. In developing the security plan, the agency/agencies responsible for levee maintenance must consider and prioritize vulnerabilities and employ an array of security measures from four basic categories to address vulnerabilities: networked detection (criterion 7.18.1); deterrence (criterion 7.18.2); physical security (criterion 7.18.3); and intrusion interdiction (criterion 7.18.4) during high-threat periods.

The LMAs utilize Security Plans (ARFCD, 2025 and City 2024b) in addition to Flood Safety Plans (ARFCD, 2018), and Emergency Action Plans (County, 2022, City 2024c). The Security Plans describe security personnel, their responsibilities, the resources available to cope with various emergencies, and measures applicable to each type of emergency or security threat. These plans are coordinated with the City of Sacramento Park Rangers, City of Sacramento Police Department, and Sacramento County Sheriff’s Department to help prevent unauthorized access and to remove and arrest those who are observed in vandalizing the levees and security measures. It is also closely coordinated with the local firefighting agency to assist in addressing the several instances of fires which occur in the dry valley conditions during the summer. Locked gates, security fences, signage, armed security if necessary, and outlined patrol URBAN LEVEL OF FLOOD PROTECTION ENGINEER’S REPORT

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24 frequency are also outlined in the Security Plan. The levee system specific security plans are provided in Appendices J5.1 and J5.2.

Therefore, the American River South Levee System has adequate plans and features to address the security of the levee system and meets ULDC 7.18.

ULDC 7.19: SEA LEVEL RISE
ULDC 7.19 requires that the effects of sea level rise be estimated and addressed for the duration during which a ULOP Finding may be valid. The sea level rise projection estimated by the State of California Department of Water Resources (DWR) in the 2022 Central Valley Flood Protection Plan (CVFPP) Update (DWR, 2022), which was based on the State of California Sea-Level Rise Guidance 2018 Update (OPC, 2018), was used for the analysis.

The 2022 Central Valley Flood Protection Plan (CVFPP) (DWR, 2022) used a 50-year sea level rise projection of 3.68 feet at San Francisco. DWR computed the effects of this sea level rise throughout the Sacramento-San Joaquin Delta with the RMA Bay-Delta model. Stage hydrographs computed by the RMA Bay-Delta model were used as downstream boundaries in the ULDC hydraulic analysis. The duration of the ULOP Finding is 20-years, therefore the use of a 50-year sea level rise projection is a conservative application. It is of interest to note that the hydraulic modeling shows that the assumed sea level rise has no effect on the DWSE for the American River South Levee System.

The American River South Levee System meets ULDC 7.19.

ULDC 7.20: EMERGENCY ACTIONS AND FLOOD SAFETY
PLANS
ULDC 7.20 includes requirements for preparing flood safety plans, as it is important that local maintaining agencies and communities understand the responsibilities of flood risk management within their jurisdictions. Specifically, the ULDC requires each public agency with the responsibility for public safety for residents protected by levees and floodwalls to have a plan for flood events and other natural or manmade, flood-related, incidents that could result in human casualties, property destruction, and economic losses.

Several agencies, including ARFCD, City of Sacramento, and Sacramento County, have the responsibility for the public safety of residents protected by the American River South Levee System. ARFCD, with primary responsibility for the levee system, has a Flood Safety Plan (ARFCD, 2018), Appendix J6.1, that outlines their planned response to flood emergencies affecting their levee systems. This plan meets the requirements of California Water Code, Section 9650; and relies on similar plans adopted by the City (City of Sacramento, 2018 and 2020) and County (Sacramento County, 2022). The State of California has a Flood Response Plan (Cal OES, 2018) which is available to MA9. No changes to the 2018 plan have been made and this is considered the most current version of the Flood Safety Plan.

The American River South Levee System’s performance during a 200-year flood event relies on the operation of flap gates and positive closure valves at drainage crossings, and installation of the stoplog URBAN LEVEL OF FLOOD PROTECTION ENGINEER’S REPORT

AMERICAN RIVER SOUTH LEVEE SYSTEM
25 structure at the Old Town flood wall, in addition to the performance of the levee. These features are identified in the O&M Manuals for the levee system (USACE, 2016a, 2016b, and 2016c). The City and County of Sacramento are responsible for operation and maintenance of these features, which are documented in their respective Emergency Operations Plans. A levee patrol plan was also prepared by the City of Sacramento (to include flood fight methods for the freeboard deficiency in Old Town Sacramento along the Sacramento River, included as Appendix J6.4.

The American River South Levee System meets ULDC 7.20 for Emergency Actions.

ULDC 8.0 OPERATIONS & MAINTENANCE
The ULDC 8.0 includes requirements related to operations and maintenance. Specifically, ULDC requires:
 The levee system must have an operation and maintenance manual consistent with USACE requirements, including inspection requirements, except as may be appropriate to deviate from those requirements to comply with the ULDC.
 The facilities providing the urban level of flood protection be operated and maintained by a public agency with the authority and resources to do so.  Damage and maintenance inadequacies identified from inspections should be prioritized and addressed in a timely manner, not awaiting the periodic review process.  Monitoring during high water needs to provide for a thorough visual inspection of both the waterside and landside levee slope (and landside berm toe area) at intervals of no more than 1 hour.
 Plans required under ULDC 7.18 for security, and ULDC 7.20 for a flood safety; other plans, such as a post-earthquake remediation plan, right-of- way plan, encroachment remediation plan, penetration remediation plan, or flood relief plan be in-place, as applicable.

This levee system is included in three USACE Supplement to Standard Operation and Maintenance Manuals (O&M Manual): (1) Sacramento River Flood Control Project, Unit No. 118 – Part No. 1. East Levee of Sacramento River from American River to Tower Bridge and South Levee of American River 0.8 miles above Mayhew Drain Downstream to Sacramento River, revised date 29 December 2016; (2) Sacramento River Flood Control Project, Unit No. 117 East Levee Sacramento River Through the City of Sacramento from Tower Bridge to Sutterville Road, revised date 29 December 2016; and (3) Sacramento River Flood Control Project, Unit No. 115 East Levee of Sacramento River from Sutterville Road to North Boundary of Reclamation District No. 744, revised date 29 December 2016. As previously indicated, this levee system is maintained by the ARFCD, City of Sacramento, and DWR Maintenance Area 9. ARFCD maintains the American River south levee and upstream approximately 0.4 miles (Unit 5). The City of Sacramento maintains the Sacramento River levee from 0.4 miles downstream of the American River to Sutterville Road. MA9 maintains the remainder of the Sacramento River east levee. The City and County of Sacramento, Caltrans, and California State University Sacramento maintain pump stations throughout the system, which were reviewed and found to be consistent with the facility operations and maintenance needs. ARFCD, the City, and MA9 perform levee inspections and patrol as outlined in the O&M Manual and address damage and maintenance issues as they arise. Security and flood safety plans are in place for each entity as described in relevant sections above. Mead & Hunt (2025b) provided a review of the referenced manuals and includes a discussion in Appendix I. Additionally, MBK Engineers performed site visits on December 15, 2023 and January 14, 2025 and performed an erosion boat tour to view general URBAN LEVEL OF FLOOD PROTECTION ENGINEER’S REPORT

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26 conditions related to Operation and Maintenance. Observations from these visits are summarized in a letter provided in Appendix G (MBK, 2025b).

The American River South Levee System meets ULDC 8.0 for Operations and Maintenance.

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27 4.0 BIBLIOGRAPHY
As mentioned in Chapter 1, this Engineer’s Report relies on dozens of other documents, reports, analyses, and evaluations. Many of these are listed in the following bibliography; however, this bibliography is mostly limited to presenting the substantial evidence required to demonstrate that an urban level of flood protection exists. Items shown BOLD are included as appendices to this report. (ARFCD, 2018). American River Flood Control District Flood Safety Plan, as required by California Water Code 9650. January 2018. (Appendix J6.1)
(ARFCD, 2017). American River Flood Control District Rodent Control & Abatement Program.

Revised October 2017. (Appendix J4.1)
(ARFCD, 2025). American River Flood Control District Security Plan – American River South Levee System. February 2025. (Appendix J5.1)
(Cal OES, 2018). Northern California Catastrophic Flood Response Plan. California Governor’s Office of Emergency Services. Part I. June 8, 2018.
(City, 2024a). Rodent Abatement & Damage Repair Standard Operating Procedure (SOP).

Department of Utilities, Operations and Maintenance, Wastewater & Drainage Division, City of Sacramento. April 29, 2024. (Appendix J4.2)
(City, 2024b). Comprehensive Flood Management Plan, Levee Security Plan. City of Sacramento.

May 2024. (Appendix J5.2)
(City, 2024c). Comprehensive Flood Management Plan. City of Sacramento. May 2024. (Appendix J6.3)
City, 2025). Sacramento River Levee Patrol Standard Operating Procedure (SOP). City of Sacramento. April 16, 2025. (Appendix J6.4)
(County, 2022). Emergency Operations Plan. Sacramento County. May 2022. (Appendix J6.2) (DWR, 2015). Rodent Abatement/Damage Repair and Rehabilitation Program. Division of Flood Management, Flood Maintenance Office, Department of Water Resources, State of California. June 2023. (Appendix J4.3)
(GEI, 2025). ULDC Geotechnical Findings Report, American River South Levee System – Sacramento River East Levee: Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00, Sacramento County, California. April 2025. (Appendix D)
(Kleinfelder, 2013a). Geotechnical Data Report, North Area Streams, SAFCA FEMA Levee Accreditation (North Area Streams, American River, Sacramento River Downstream of American River, and Beach Lake Levee). Sacramento County. May 31, 2013.

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28 (Kleinfelder, 2013b). Problem Identification Report, North Area Streams, SAFCA FEMA Levee Accreditation (North Area Streams, American River, Sacramento River Downstream Of American River, and Beach Lake Levee). Sacramento County, California. September 18, 2013. (Kleinfelder, 2015). Draft ULDC Geotechnical Results Summary, North Area Streams, SAFCA FEMA Levee Accreditation (North Area Streams, American River, Sacramento River Downstream of American River, and Beach Lake Levee). Sacramento County, California. December 18, 2015. (Kleinfelder, 2025a) Seismic Performance Summary Report, American River/South Sacramento Basin, ULDC & FEMA Levee Certification Project, Sacramento Area Flood Control Agency Levee Systems, Sacramento County, California. April 16, 2025. (Appendix C to Kleinfelder, 2025b Appendix E) (Kleinfelder, 2025b) ULDC Geotechnical Finding – Sacramento River Eat Levee Stations 1000+00 to 1080+00, 1150+00 to 1185+00, 1206+00 to 1285+75, 1418+00 to 1534+40, and 1640+00 to 1770+00. April 17, 2025. (Appendix E)
(Kleinfelder, 2025c). Post Earthquake Remediation Plan. April 18, 2025. (Appendix J7) (MBK, 2016a). Technical Memorandum. Overview of High Hazard Encroachments to Support Adequate Progress Towards an Urban Level of Flood Protection. Sacramento, California. April 15, 2016. (MBK, 2016b). Technical Memorandum. Overview of High Hazard Vegetation to Support Adequate Progress Towards an Urban Level of Flood Protection. Sacramento, California. April 15, 2016. (MBK, 2025a) Urban Levee Design Criteria, American River South Levee System Erosion Evaluation Report.

January 2025.
(MBK, 2025b) SAFCA American River South Levee System, Levee O&M Review in Support of FEMA and ULDC Certification. February 14, 2025. (Appendix G) (MBK, 2025c) American River South Levee System Framework for Encroachment Remediation Plan.

April 1, 2025. (Appendix J2)
(MBK, 2025d) American River South Levee System- Determination of the Urban Levee Design Criteria Design Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee. April 9, 2025. (Appendix C)
(MBK, 2025e) Geotechnical Due Diligence Report – Urban Levee Design Criteria American River South Levee Station 1000+00 to 1635+50, SAFCA FEMA and ULDC Evaluation, Sacramento County, CA. April 10, 2025. (Appendix F)
(MBK, 2025f) Sacramento County and City of Sacramento Recommended Right-of-Way Plan to Comply with ULDC Criteria 7.11 American River South Levee System. April 2025. (Appendix J1) (Mead & Hunt, 2024) Appendix D. ANLS Wind Setup and Wave Runup Analysis. December 5, 2024. (Appendix D to Mead & Hunt, 2025b Appendix I)
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29 (Mead & Hunt, 2025a) Penetration Exceptions Work Plan, American River South Levee System (ASLS) SAFCA Due Diligence Review for Urban Levee Design Criteria Section 7.13. March 21, 2025. (Appendix J3)
(Mead & Hunt, 2025b) American South Levee System Due Diligence Review for ULDC & FEMA Certification. April 15, 2025. (Appendix I)
(Psomas, 2025) O&M Right of Way Map, American River South Levee System. April 1, 2025. (Appendix H)
(SAFCA, 2015). Sacramento Federal Emergency Management Agency Certification White Paper for Addressing Encroachments. August 6, 2015.
(SAFCA, 2024) Urban Level of Flood Protection Annual Report, dated August 2024. (URS, 2008). Levee Seismic Vulnerability Assessment Methodology Report. 2008. (URS, 2009). Geotechnical Levee Practice Standard Operating Procedures. [USACE Sacramento Districts].

Sacramento, California. 2009.
(URS, 2010). Modified Supplemental Geotechnical Data Report (MSGDR), Natomas East Main Drainage Canal (NEMDC) West Study, Urban Levee Geotechnical Evaluations Program Contract 4600007418 and 4600008101. [Department of Water Resources]. November 2010. (URS, 2015a). Geotechnical Evaluation Report, Volume 1, Existing Conditions, Natomas East Main Drainage Canal, West Study Area, Urban Levee Evaluations Project, Contract 4600008101. [Department of Water Resources]. January 2015.
(URS, 2015b). Geotechnical Evaluation Report (Existing Conditions and Seismic Assessment), Natomas North Study Area, Urban Levee Evaluations Project, Contract 4600008101. [Department of Water Resources]. March 2015.
(USACE, 2014) Untitled Letter. Department of the Army, U.S. Army Engineer District, Sacramento Corps of Engineer. (No date on letter. File date is June 5, 2014. (USACE, 2016a) Supplement to Standard Operation and Maintenance Manual, Sacramento River Flood Control Project, Unit No. 118 – Part No. 1. East Levee of Sacramento River from American River to Tower Bridge and South Levee of American River 0.8 miles above Mayhew Drain Downstream to Sacramento River, USACE. Revised date 29 December 2016.
(USACE, 2016b) Supplement to Standard Operation and Maintenance Manual, Sacramento River Flood Control Project, Unit No. 117 East Levee Sacramento River Through the City of Sacramento from Tower Bridge to Sutterville Road, USACE. Revised date 29 December 2016. (USACE, 2016c) Supplement to Standard Operation and Maintenance Manual, Sacramento River Flood Control Project, Unit No. 115 East Levee of Sacramento River from Sutterville Road to North Boundary of Reclamation District No. 744, USACE. Revised date 29 December 2016. (USACE, 2023) USACE 2021 Inspection Report, dated December 1, 2023.

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!>
City Sump 91
City Sump 91
A m e r i c a n
R i v e r

AMERICAN RIVER

SOUTH LEVEE
Sacramento River East Levee
(See Figure 2)
CSU
Sacramento
River
Park
Fairbairn
Water Treatment Plant
!>
D-06: County
Drainage Pump Stn
"S
"S
Mayhew Drain
Closure Structure
UPRR
Bridge
UPRR
Bridge
Hwy 160
Bridges
Interstate 5
Bridge
Jibboom St
Bridge
Pedestrian
Bridges
!>
City Sump 155
!>
City Sump 10
Business 80
Bridge
Downtown
Sacramento
§¨¦5
§¨¦5
)*+,-80
)*+,-80
£¤50
£¤50 £¤50
¬«160
¬«160
_^ State Capitol
East
Sacramento

AMERICAN RIVER

SOUTH LEVEE
S a
c
r
a
me nt o R i v
e r
!>
City Sump 111
Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community

URBAN LEVEE DESIGN CRITERIA

AMERICAN RIVER SOUTH LEVEE SYSTEM

AMERICAN RIVER SOUTH LEVEE
FIGURE 2A
0 1,500 3,000 6,000 Feet
.

F:\SAFCA\FEMA_ULDC\FEMA\American South\GIS\Figure 1 - American River South Levee map 012725.mxd Legend
American River South Levee
Other Federal Project Levees
1100+00
1150+00
1200+00
1250+00
1 350+
00 1400+00
1450+00
1500+00
1550+00
16 0
0 +
0 0
1650+00
1700+00
1750+00
1000+00
1050+00
1770+00

SACRAMENTO RIVER EAST LEVEE
I Street
Bridge
Jibboom St
Bridge
Downtown
Sacramento
§¨¦5
)*+,-80
£¤50
_^ State Capitol
East
Sacrame
American River
South Levee
(See Figure 1)
Sacram
ent
o
River
§¨¦5
SACRAMENTO RIVER EAST LEVEE §¨¦5
Beach Lake North Levee
(separate ULDC evaluation)
Land Park
Little
Pocket
Pocket
Freeport
Tower
Bridge
Pioneer
Bridge
Freeport
Bridge
§¨¦80
§¨¦80
¬«99
City Sump 02
!>
!>
City Sump 41
!>
CWTP
Outfall
!>
City Sump 63
!>
City Sump 70
!>
City Sump 132
!>
City Sump 28
!> City Sump 34
Freeport Regional Water Facility
!>
Sacram
ento
River
Limit of Study
Pioneer Reservoir
Outfall
Railyards Stormwater
Outfall
Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community

URBAN LEVEE DESIGN CRITERIA

AMERICAN RIVER SOUTH LEVEE SYSTEM

SACRAMENTO RIVER EAST LEVEE
FIGURE 2
0 2,000 4,000 6,000
Feet
.

F:\SAFCA\FEMA_ULDC\FEMA\American South\GIS\Figure 2 - Sacramento River East Levee map 032025.mxd Legend
Sacramento River East Levee
Other Federal Project Levees
Major Highways
Appendix A.

American River South ULDC
Consultant Certification Statements
ENGINEER’S OPINION
ULDC 7.1: DESIGN WATER SURFACE ELEVATION
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

AMERICAN RIVER SOUTH LEVEE SYSTEM
All information, calculations, definitions, descriptions, restrictions, limitations, or other pertinent data contained in or referenced in the following document forms the basis of this opinion.  American River South Levee System – Determination of the Urban Levee Design Criteria Design Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee, prepared by MBK Engineers, dated April 9, 2025.

LIMITATIONS OF ENGINEER’S OPINION
Consistent with current practice, this opinion of expected flood control system performance is valid for 20 years from the date of the SAFCA certification and assumes the levee will be properly maintained during the certification period.

It is assumed that “sound engineering practices” are practices that are performed in a manner consistent with the degree of skill and care ordinarily exercised by members of the profession currently practicing in the same locality under similar conditions at the time the work was performed.

The use of the term certification in this document is based on the following:

Per California Business And Professions Code, Division 3, Chapter 7, Article 3, 6735.5: “The use of the word “certify” or “certification” by a registered professional engineer in the practice of professional engineering or land surveying constitutes an expression of professional opinion regarding those facts or findings which are the subject of the certification, and does not constitute a warranty or guarantee, either expressed or implied.”

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.1 Design Water Surface Elevation, as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Don Trieu, PE
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825-6579
________________________________________________4/14/2025 Signature Date
Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.2: MINIMUM TOP OF LEVEE
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

AMERICAN RIVER SOUTH LEVEE SYSTEM
All information, calculations, definitions, descriptions, restrictions, limitations, or other pertinent data contained in or referenced in the following document forms the basis of this opinion.  American River South Levee System - Determination of the Urban Levee Design Criteria Design Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee, prepared by MBK Engineers, dated April 9, 2025.

The use of the term certification in this document is based on the following:

Per California Business And Professions Code, Division 3, Chapter 7, Article 3, 6735.5: ”The use of the word “certify” or “certification” by a registered professional engineer in the practice of professional engineering or land surveying constitutes an expression of professional opinion regarding those facts or findings which are the subject of the certification, and does not constitute a warranty or guarantee, either expressed or implied.”

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.2 Minimum Top of Levee through exception, as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Don Trieu, PE
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825-6579
______________________________________________4/14/2025__________ Signature Date Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.3: SOIL SAMPLING, TESTING, AND LOGGING
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

AMERICAN RIVER SOUTH LEVEE SYSTEM: SACRAMENTO RIVER EAST LEVEE – STATION 1080+00 TO 1150+00, STATION 1185+00 TO 1206+00, STATION 1285+75 TO 1418+00, AND STATION 1534+40 TO 1640+00
All information, calculations, definitions, descriptions, restrictions, limitations, or other pertinent data contained in or referenced in the following document forms the basis of this opinion.  ULDC Geotechnical Findings Report American River South Levee System – Sacramento River East Levee: Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00, prepared by GEI Consultants, Inc., dated April 2025.

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC 7.3 Soil Sampling, Testing and Logging, as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Alberto Pujol, P.E., G.E.

GEI Consultants, Inc.
180 Grand Avenue, Suite 950
Oakland, CA 94612
________________________________________________04/17/2025________ Signature Date Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.3: SOIL SAMPLING, TESTING, AND LOGGING
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

AMERICAN RIVER SOUTH LEVEE SYSTEM: SACRAMENTO RIVER EAST LEVEE - STATIONS 1000+00 TO 1080+00, 1150+00 TO 1185+00, 1206+00 TO 1285+75, 1418+00 TO 1534+40, AND 1640+00 TO 1770+00
All information, calculations, definitions, descriptions, restrictions, limitations, or other pertinent data contained in or referenced in the following document forms the basis of this opinion.  ULDC Geotechnical Finding – American River South Levee System Sacramento River East Levee Stations 1000+00 to 1080+00, 1150+00 to 1185+00, 1206+00 to 1285+75, 1418+00 to 1534+40, and 1640+00 to 1770+00, prepared by Kleinfelder, dated April 17, 2025.

This opinion by a registered professional engineer does not constitute a warranty or guarantee of performance, express or implied. The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.3 Soil Sampling, Testing and Logging through exception, as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Timothy Williams, PE, GE
Kleinfelder
3130 Kilgore Road, Suite 200
Rancho Cordova, CA 95670
________________________________________________April 17, 2025_ Signature Date Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.3: SOIL SAMPLING, TESTING, AND LOGGING
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

AMERICAN RIVER SOUTH LEVEE: STATION 1000+00 TO 1635+50
All information, calculations, definitions, descriptions, restrictions, limitations, or other pertinent data contained in or referenced in the following document forms the basis of this opinion.  Geotechnical Due Diligence Report – Urban Levee Design Criteria American River South Levee Station 1000+00 to 1635+50; American River South Levee and Sacramento River East Levee SAFCA FEMA and ULDC Evaluation; Sacramento County, California, prepared by MBK Engineers, dated April 10, 2025.

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.3 Soil Sampling, Testing and Logging as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Rebecca L. Money, PE, GE
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825
________________________________________________4/14/2025 Signature Date Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.4: SLOPE STABILITY FOR INTERMITTENTLY LOADED LEVEES This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.4 Slope Stability for Intermittently Loaded Levees, as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Alberto Pujol, P.E., G.E.

GEI Consultants, Inc.
180 Grand Avenue, Suite 950
Oakland, CA 94612
________________________________________________04/17/2025________ Signature Date Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.4: SLOPE STABILITY FOR INTERMITTENTLY LOADED LEVEES This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.4 Slope Stability for Intermittently Loaded Levees by exception as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

LOADED LEVEES
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.4 Slope Stability for Intermittently Loaded Levees as described in the above reference document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Rebecca L. Money, PE, GE
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825
___________________________________________4/14/2025_____ Signature Date Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.5: UNDERSEEPAGE FOR INTERMITTENTLY LOADED LEVEES This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

AMERICAN RIVER SOUTH LEVEE SYSTEM: SACRAMENTO RIVER EAST LEVEE – STATION 1080+00 TO 1150+00, STATION 1185+00 TO 1206+00, STATION 1285+75 TO 1418+00, AND STATION 1534+40 TO 1640+00
All information, calculations, definitions, descriptions, restrictions, limitations, or other pertinent data contained in or reference in the following document forms the basis of this opinion.  ULDC Geotechnical Findings Report American River South Levee System – Sacramento River East Levee: Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00, prepared by GEI Consultants, Inc., dated April 2025.

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.5 Underseepage for Intermittently Loaded Levees, as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Alberto Pujol, P.E., G.E.

LIMITATIONS OF ENGINEER’S OPINION
Consistent with current practice, this opinion of expected flood control system performance is valid for 20 years from the date of the SAFCA certification and assumes the levees will be properly maintained during the certification period.

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.5 Underseepage for Intermittently Loaded Levees through exception as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Timothy Williams, PE, GE
Kleinfelder
3130 Kilgore Road, Suite 200
Rancho Cordova, CA 95670
________________________________________________ April 17, 2025____ Signature Date
Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.5: UNDERSEEPAGE FOR INTERMITTENTLY

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.5 Underseepage for Intermittently Loaded Levees, as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Rebecca L. Money, PE, GE
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825
________________________________________________4/14/2025____ Signature Date Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.6: FREQUENTLY LOADED LEVEES
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

AMERICAN RIVER SOUTH LEVEE SYSTEM
All information, calculations, definitions, descriptions, restrictions, limitations, or other pertinent data contained in or referenced in the following document forms the basis of this opinion.  Sacramento Area Flood Control Agency; Urban Level of Flood Protection Engineer’s Report for the American River South Levee System, prepared by SAFCA, dated April 2025.

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.6 Frequently Loaded Levees, as described in the above referenced document;
 data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Tom Engler, PE, CFM
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825-6579
____________________________________________ 4/17/2025___ Signature Date
Not Valid Unless Stamped
Expires March 31, 2027
ENGINEER’S OPINION
ULDC 7.7: SEISMIC VULNERABILITY
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

LIMITATIONS OF ENGINEER’S OPINION
Consistent with current practice, this opinion of expected flood control system performance is valid for 20 years from the date of the SAFCA certification and assumes the levees will be properly maintained during the certification period.

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.7 Seismic Vulnerability as described in the above referenced document;
 data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and  the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Timothy Williams, PE, GE
Kleinfelder
3130 Kilgore Road, Suite 200
Rancho Cordova, CA 95670
_________________________________________________ April 17, 2025_ Signature Date
Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.8: LEVEE GEOMETRY
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC 7.8 Levee Geometry from a geotechnical standpoint as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Alberto Pujol, P.E., G.E.

GEI Consultants, Inc.
180 Grand Avenue, Suite 950
Oakland, CA 94612
________________________________________________04/17/2025________ Signature Date Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.8: LEVEE GEOMETRY (GEOTECHNICAL)
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

Timothy Williams, PE, GE
Kleinfelder
3130 Kilgore Road, Suite 200
Rancho Cordova, CA 95670
_______________________________________________ April 17, 2025 Signature Date
Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.8: LEVEE GEOMETRY (GEOTECHNICAL)
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC 7.8 Levee Geometry from a geotechnical standpoint as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Rebecca L. Money, PE, GE
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825
_____________________________________________4/14/2025
Signature Date Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.9: INTERFACES AND TRANSITIONS (GEOTECHNICAL)
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.9 Interfaces and Transitions from a geotechnical standpoint, as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Alberto Pujol, P.E., G.E.

GEI Consultants, Inc.
180 Grand Avenue, Suite 950
Oakland, CA 94612
________________________________________________04/17/2025________ Signature Date Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.9: INTERFACES AND TRANSITIONS (GEOTECHNICAL)
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.9 Interfaces and Transitions from a geotechnical standpoint as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Timothy Williams, PE, GE
Kleinfelder
3130 Kilgore Road, Suite 200
Rancho Cordova, CA 95670
________________________________________________ April 17, 2025__ Signature Date
Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.9: INTERFACES AND TRANSITIONS (GEOTECHNICAL)
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.9 Interfaces and Transitions from a geotechnical perspective as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Rebecca L. Money, PE, GE
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825
__________________________________________________4/14/2025______ Signature Date Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.10: EROSION
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.10 Erosion and Transitions as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Tom Engler, PE, CFM
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825-6579
__________________________________________________4/14/2025_______ Signature Date Not Valid Unless Stamped
Expires March 31, 2027
ENGINEER’S OPINION
ULDC 7.11: RIGHT-OF-WAY
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

AMERICAN RIVER SOUTH LEVEE SYSTEM
All information, calculations, definitions, descriptions, restrictions, limitations, or other pertinent data contained in or referenced in the following document forms the basis of this opinion.  O&M Right of Way Map; American River South Levee System, prepared by Psomas, dated, April 1, 2025.

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.11 Right-of-Way through exception as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Tom Engler, PE, CFM
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825-6579
___________________________________________________4/15/2025 Signature Date
Not Valid Unless Stamped
Expires March 31, 2027
ENGINEER’S OPINION
ULDC 7.12: ENCROACHMENTS
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.12 Encroachments as described in the above referenced document;
 data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Tom Engler, PE, CFM
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825-6579
________________________________________________4/15/2025____ Signature Date Not Valid Unless Stamped
Expires March 31, 2027
ENGINEER’S OPINION
ULDC 7.12: ENCROACHMENTS
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

AMERICAN RIVER SOUTH LEVEE SYSTEM
All information, calculations, definitions, descriptions, restrictions, limitations, or other pertinent data contained in and evaluated in the following document forms the basis of this opinion.  American River South Levee System; Due Diligence Review for ULDC & FEMA Certification, prepared by Mead & Hunt, dated April 15, 2025.

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.12 Encroachments as described in the above referenced document;
 data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Stephen Sullivan, PE
Mead & Hunt
180 Promenade Circle, Suite 240
Sacramento, CA 95834
___________________________________________________________________ Signature Date Not Valid Unless Stamped
April 16, 2025
ENGINEER’S OPINION
ULDC 7.13: PENETRATIONS
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.13 Penetrations through exception as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge;
 the analyses in this opinion have been performed in accordance with DWR’s ULDC and/or sound engineering practices; and
 the structural works are in place and functioning as intended for the 200-year ULDC event.

Rebecca L. Money, PE, GE
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825
_________________________________________________4/14_/2025 Signature Date
Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.13: PENETRATIONS
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.13 Penetrations through exception as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge;
 the analyses supporting this opinion have been performed in accordance with DWR’s ULDC and/or sound engineering practices; and
 the structural works are in place and functioning as intended for the 200-year ULDC event.

Stephen Sullivan, PE
Mead & Hunt
180 Promenade Circle, Suite 240
Sacramento, CA 95834
______________________________________________________________ Signature Date Not Valid Unless Stamped
April 16, 2025
ENGINEER’S OPINION
ULDC 7.14: FLOODWALLS, RETAINING WALLS, AND CLOSURE STRUCTURES (CIVIL/STRUCTURAL)
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of ULDC 14 Floodwalls, Retaining Walls, and Closure Structures (Civil) as described in the above referenced document.  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge;
 the analyses supporting this opinion have been performed in accordance with DWR’s ULDC and/or sound engineering practices; and
 the structural works are in place and functioning as intended for the 200-year ULDC.

CLOSURE STRUCTURES (GEOTECHNICAL)
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.14 Floodwalls, Retaining Walls, and Closure Structures for geotechnical requirements as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge;  the analyses supporting this opinion have been performed in accordance with DWR’s ULDC and/or sound engineering practices; and
 the structural works are in place and functioning as intended for the 200-year ULDC event.

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.14 Floodwalls, Retaining Walls, and Closure Structures for geotechnical requirements as described in the above referenced document;
 data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge;
 the analyses supporting this opinion have been performed in accordance with DWR’s ULDC and/or sound engineering practices; and
 the structural works are in place and functioning as intended for the 200-year ULDC event.

Rebecca L. Money, PE, GE
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825
_____________________________________________4/14/2025______ Signature Date Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.15: ANIMAL BURROWS
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

AMERICAN RIVER SOUTH LEVEE SYSTEM
All information, calculations, definitions, descriptions, restrictions, limitations, or other pertinent data contained in or evaluated in the following documents form the basis of this opinion.  SAFCA American River South Basin Levee O&M Review in Support of FEMA and ULDC Certification, prepared by MBK Engineers, dated February 14, 2025.
 Rodent Control & Abatement Program, prepared by American River Flood Control District, dated October 2017.
 Rodent Abatement & Damage Repair Standard Operating Procedure. City of Sacramento, dated April 29, 2024.  Rodent Abatement/Damage Repair and Rehabilitation Program, Department of Water Resources, dated May 2015.

LIMITATIONS OF ENGINEER’S OPINION
Consistent with current practice, this opinion of expected flood control system performance is valid for 20 years from the date of the SAFCA certification and assumed the levees will be properly maintained during the certification period.

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.15 Animal Burrows as described in the above referenced documents;
 data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Tom Engler, PE, CFM
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825-6579
________________________________________________4/15/2025____________ Signature Date
Not valid unless stamped
Expires March 31, 2027 ON
ENGINEER’S OPINION
ULDC 7.16: LEVEE VEGETATION
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.16 Levee Vegetation as described in the above referenced document;
 data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Tom Engler, PE, CFM
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825-6579
___________________________________________________4/14/2025________ Signature Date
Not Valid Unless Stamped
Expires March 31, 2025

ENGINEER’S OPINION
ULDC 7.17: WIND SETUP AND WAVE RUNUP
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.17 Wind Setup and Wave Runup as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Stephen Sullivan, PE
Mead & Hunt
180 Promenade Circle, Suite 240
Sacramento, CA 95834
___________________________________________________________________ Signature Date
Not Valid Unless Stamped
April 16, 2025
ENGINEER’S OPINION
ULDC 7.18: SECURITY
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

AMERICAN RIVER SOUTH LEVEE SYSTEM
All information, calculations, definitions, descriptions, restrictions, limitations, or other pertinent data contained in or evaluated in the following document forms the basis of this opinion.  Security Plan, prepared by American River Flood Control District, dated March 2024.  Comprehensive Flood Management Plan, Levee Security Plan, City of Sacramento, May 2024.

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.18 Security as described in the above referenced documents;
 data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Tom Engler, PE, CFM
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825-6579
________________________________________________4/15/2025________ Signature Date
Not Valid Unless Stamped
Expires March 31, 2027
ENGINEER’S OPINION
ULDC 7.19: SEA LEVEL RISE
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.19 Sea Level Rise as described in the above referenced document;
 data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Don Trieu, PE
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825-6579
____________________________________________4/14/2025
Signature Date Not Valid Unless Stamped
ENGINEER’S OPINION
ULDC 7.20: EMERGENCY ACTIONS AND FLOOD SAFETY PLANS
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

AMERICAN RIVER SOUTH LEVEE SYSTEM
All information, calculations, definitions, descriptions, restrictions, limitations, or other pertinent data contained in or referenced in the following documents form the basis of this opinion.  American River Flood Control District Flood Safety Plan, as required by California Water Code 9650, January 2018.
 Comprehensive Flood Management Plan, City of Sacramento, dated May 2024.  Emergency Operations Plan, Sacramento County, dated May 2022.

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 7.20 Emergency Actions as described in the above referenced documents;
 data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

Tom Engler, PE, CFM
MBK Engineers
455 University Avenue, Suite 100
Sacramento, CA 95825-6579
________________________________________________4/14/2025____ Signature Date
Not valid unless stamped.

Expires March 31, 2027
ENGINEER’S OPINION
ULDC 8.0 OPERATIONS AND MAINTENANCE
This opinion is made to assist the Sacramento Area Flood Control Agency (SAFCA) in complying with the requirements, definitions, and descriptions in the California Department of Water Resources’ (DWR) Urban Levee Design Criteria (ULDC) (May 2012) and to support SAFCA’s certification of the Urban Levee System of:

The use of the term certification in this document is based on the following:

OPINION
This Engineer’s Opinion attests that:
 the subject levee system meets the requirements of the ULDC for Section 8.0 Operations and Maintenance as described in the above referenced document;  data used in the evaluations and analyses supporting this opinion are accurate to the best of my knowledge; and
 the analyses have been performed in accordance with DWR’s ULDC and/or sound engineering practices.

American River South ULDC
Independent Panel of Experts
Report and Comment Closeout
April 22, 2025
Mr. Tom Engler, PE
MBK Engineers
455 University Ave, Suite 100
Sacramento, CA 95825
Dear Mr. Engler:

Subject: Urban Level of Flood Protection Engineer’s Report for the American River South Levee System
Independent Panel of Experts’ Concurrence with Engineer’s Report City of Sacramento and Sacramento County
At your request, the Independent Panel of Experts (IPE) (Dr. David Williams, P.E., PH, CFM, BC.WRE, Mr. Michael Hughes, PE, and Mr. Darren Mack, PE, GE) has conducted an independent quality assurance review of the Urban Level of Flood Protection (ULOP) Engineers’ Report for the American River South Levee System that provides flood protection within the jurisdiction of the City of Sacramento and Sacramento County. The American River South Levee System consists of the American River south (left) levee, Sacramento River east (left) levee, and Beach Lake north (right) levee.

Beach Lake north (right) levee was not included as part of this IPE review.

The Engineer’s Report and its supporting documents are intended to provide substantial evidence that the American River South Levee System meets the California Department of Water Resources’ (DWR’s) ULOP Criteria for a 200-year flood event (1-in-200 annual chance of exceedance) in accordance with the DWRs’ Urban Levee Design Criteria (ULDC) issued in May 2012.

IPE Charge and Scope of Work
The IPE has been tasked to provide independent, expert opinion regarding certification. Tasks include, but are not limited to, the following:
• Preparation and attendance of IPE meetings;
• Review and comment on Due Diligence reports supporting ULOP certifications; • Review and comment on the Engineer’s Reports supporting the certifications; and • Preparation of IPE’s report documenting opinion on whether the flood system meets ULOP certification standards.

Materials provided to the IPE for review included the draft Engineer’s Report for the American River South Levee, dated February 2025, and the following supporting documents:
• Appendix C: DRAFT American River South Levee System - Determination of the Urban Levee Design Criteria Design Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee, prepared by MBK, dated April 9, 2025.
• Appendix D: DRAFT ULDC Geotechnical Findings Report, American River South Levee System – Sacramento River East Levee: Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00, prepared by GEI Consultants, dated March 2025.
• Appendix E: ULDC Geotechnical Findings, American River South Levee System, Sacramento River East Levee Stations 1000+00 to 1080+00, 1150+00 to 1185+00, 1206+00 to 1285+75, 1418+00 to 1534+40, and 1640+00 to 1770+00, prepared by Kleinfelder, dated March 24, 2025. • Appendix F: Geotechnical Due Diligence Report – Urban Levee Design Criteria, American River South Levee Station 1000+00 to 1635+50, prepared by MBK, dated January 31, 2025. • Appendix G: SAFCA American River South Basin, Levee O&M Review in Support of FEMA and ULDC Certification, prepared by MBK, dated February 14, 2025. • Appendix I - AMERICAN RIVER SOUTH LEVEE SYSTEM Due Diligence Review for ULDC & FEMA Certification, prepared by Mead & Hunt, dated March 21, 2025. • Appendix J2 - American River South Levee System Framework for Encroachment Remediation Plan, prepared by MBK, dated April 01, 2025.
• Appendix J3 - Penetration Exceptions Work Plan, American River South Levee System (ASLS) SAFCA Due Diligence Review for Urban Levee Design Criteria Section 7.13, prepared by Mead & Hunt, dated March 21, 2025.
• Appendix J7 – Post-Earthquake Remediation Plan ULDC & FEMA Levee Certification Project, Sacramento Area Flood Control Agency Levee Systems, prepared by Kleinfelder, Dated March 18, 2025.

Other information was provided for context but are not presented in this letter.

DWR Urban Level of Flood Protection Criterion EVD-1:

Section 2.0 of the ULOP provides the following criterion that is considered by DWR to be necessary for reasonable and responsible decision making.

EVD-1: Substantial evidence in the record to support a finding related to an urban level of flood protection based on flood management facilities providing the required level of flood protection shall include the following, at a minimum:
• A report prepared by a Professional Civil Engineer registered in California to document the data and analyses for demonstrating that the property, development project, or subdivision has an urban level of flood protection.
• A report by an Independent Panel of Experts on the review of the report prepared by the Professional Civil Engineer.
• A response by the Professional Civil Engineer to the comments from the Independent Panel of Experts.
• Any additional data and information that cities and/or counties use to make the finding.

DWR’s ULDC document presents mainly procedural criteria associated with making a finding consistent with legislative requirements. DWR considers that an urban level of flood protection could be achieved by structural and nonstructural means, or a combination of both. Therefore, DWR’s ULDC, as described below, are incorporated by reference in the ULOP Criteria.

DWR’s ULDC document provides the engineering criteria and guidance for the design, evaluation, operation, and maintenance of levees and floodwalls that provide a 200-year ULOP and outlines 20 technical areas associated with levee integrity and the evaluations needed for compliance, these being:
• Section 7.1 - Design Water Surface Elevation
• Section 7.2 - Minimum Top of Levee
• Section 7.3 - Soil Sampling, Testing, and Logging
• Section 7.4 - Slope Stability for Intermittently Loaded Levees • Section 7.5 - Underseepage for Intermittently Loaded Levees • Section 7.6 - Frequently Loaded Levees
• Section 7.7 - Seismic Vulnerability
• Section 7.8 - Levee Geometry
• Section 7.9 - Interfaces and Transitions
• Section 7.10 - Erosion
• Section 7.11 - Right-of-Way
• Section 7.12 - Encroachments
• Section 7.13 - Penetrations
• Section 7.14 - Floodwalls, Retaining Walls, and Closure Structures • Section 7.15 - Animal Burrows
• Section 7.16 - Levee Vegetation
• Section 7.17 - Wind Setup and Wave Runup
• Section 7.18 - Security
• Section 7.19 - Sea Level Rise
• Section 7.20 - Emergency Actions
The above listed sections were referenced during the IPE review to verify that the completed levee system certification meets the ULDC standards.

Independent Panel of Experts Review and Findings
The IPE reviewed the Engineer’s Report and supporting documents (Appendix C, D, E, F, G, and I, and remediation plans in Appendix J), attended meetings with the certification team, visited the levee sites, and provided review comments and “backcheck” replies to Engineer’s team responses. A spreadsheet that documents the IPE comments, Engineer’s team responses, and comment closures is attached to this letter. Changes, clarifications, and improvements to the Engineer’s Report, and supporting documents, were made where needed.

Based on its review, the IPE provides the following findings for the American River south (left) levee and Sacramento River east (left) levee portions of the American River South Levee System:
• The certification team, in the IPE’s opinion, had followed the standards of engineering required for certifying the levees included in the American River South Levee System. • Adequate and appropriate information1 has been gathered and presented to the IPE to perform the review needed to support the certification package.
• The engineering documentation provided were appropriate to accurately provide compliance with the ULDC to address the technical areas listed above.
• The references cited in the Engineer’s Report (including the Due Diligence and Engineer’s Opinions reports), provide the appropriate and adequate information to support those Opinions. • Exceptions to ULDC criteria requested by the certification team are reasonable and adequately supported.
• In the IPE’s judgment, the documentation, evaluations, and management approaches were completed in accordance with sound engineering practices2to provide protection up to the 200- year flood event, and support ULOP and ULDC certifications of the American River South Levee System.
1 Assessment of adequacy and appropriateness for geotechnical issues along the American River South Levee relies heavily on the Statement of Performance provided by US Army Corps of Engineers. 2 It is assumed that “sound engineering practices” are practices that are performed in a manner consistent with the degree of skill and care ordinarily exercised by members of the profession currently practicing in the same locality under similar conditions.

The Engineer’s Report is a requirement to obtain ULOP Certification for an urban levee system. The ULOP Criteria, Sub-Section EVD-1, requires a report by the IPE documenting its review of the Engineer’s Report and its supporting documents. This letter and its attachment serve as documentation of the IPE’s review and concurrence that the completed levee system provides the required Urban Level of Flood Protection.

Respectfully submitted,
Sacramento Area Levee Certification Project
Independent Panel of Experts
_____________________________ ____________________________ Michael Hughes, P.E. Darren Mack, P.E., G.E.

Independent Expert Panel Member Independent Expert Panel Member _______________________________________
Dr. David T. Williams, P.E., PH, CFM, BC.WRE
Independent Expert Panel Member

No. DOCUMENT LOCATION IN DOCUMENT

IPE'S COMMENT
(03/02/2025)

ENGINEER'S RESPONSE
(03/24/2025)
IPE's COMMENT
(04/09/2025)

ENGINEER'S RESPONSE
(04/10/2025)
IPE's FINAL COMMENT / CLOSURE
(04/16/2025)
1 1.0 Introduction
First sentence of the last paragraph states no structural improvements are required, but this is not the case for Beach Lake north levee. Need to discuss the intent of this paragraph with MBK.

Beach Lake does require structural improvements, but is not included in this package. The 1st sentence in the last paragraph of Section 1.0 was revised to indicate this (MBK - Rebecca Money, 3/5/25) Accepted - closed
2 3.0 Physical Description, American River
south, 1st para.

Mayhew Drain is stated as being at Station 1552+45. Elsewhere in the report Station 1555+50 is used. Figure 2 shows Station 1550+00. Also, 10.5 miles upstream of Station 1000+00 is Station 1554+40. Please correct and make consistent.

The Mayhew Drain crosses the American River South Levee stationing at aproximately 1556+00, which is equivalent to levee mile 10.53, due to significant figures levee mile 10.5 will continue to be used. This stationing nomenclature was made consistent throughout. (MBK - Rebecca Money, 3/5/25) Accepted - closed
3 4.0 Performance History, American River south, 2nd para what is the vertical datum for the gage heights? Also for other sections The vertical datum is NAVD88, the text was revised in Section 4.0, Paragraph 2. (MBK - Rebecca Money, 3/5/25) Accepted - closed 4 4.0 Performance History, American River
south, 2nd para last bullet - should be major instead of minor. Also for east levee The text was revised as suggested in Section 4, 2nd paragraph and last bullet for ARS section and SREL section. (MBK - Rebecca Money, 3/5/25) Accepted - closed 5 Table 1. Any associated frequencies for each threshold events/elevations? If so, suggest putting in the table Estimated flow frequencies were added to Table 1. (MBK - Rebecca Money and Don Trieu, 3/20/25) Accepted - closed 6 4.0 Performance History, Sacramento River east, 1st para who produced the "subsequent reports" and what did they discuss? What does "occurred every year" followed by intermittent years mean? Section 4.0, SREL, paragraph 1 was updated to indicate erosion reports were prepared by USACE and also provide clarification on when reports were published. (MBK - Rebecca Money, 3/20/25) Accepted - closed7 4.0 Performance History, Sacramento River east, 2nd para What kind of repairs were made for the erosion? Riprap? Section 4.0, 2nd paragraph, was revised to indicate repairs consisted of rock rip rap. (MBK - Rebecca Money, 3/20/25) Accepted - closed 8 Table 2. suggest adding flows and associated frequencies to the table As for Table 2, there is no stage-frequency curve for I-Street so we can't define frequency or flow. No changes to Table 2 were made. (MBK - Rebecca Money and Don Trieu, 3/20/25) Accepted - closed
9 ULDC 7.3, American River South, 1st para, first three sentences.

There doesn't appear to be a rationale for the statement 'Therefore, the American River south levee appears to meet ULDC 7.3….............." Furthermore, there is an exception for this certification. Recommend deleting the first three sentences and starting with" MBK (2025d) and Kleinfelder (2025) have reviewed....." ULDC 7.3, ARS 1st pargraph was reworded as suggested. (MBK - Rebecca Money, 3/5/25) It is still confusing why the statement - 'This information in combination with the existing explorations is considered sufficient to meet ULDC 7.3' is included and then the next paragraphs states that 7.3 is met by exception. This seesm contradictory. Comment remains open.

Sentence in reference was removed. FYI, the text was further revised to indicate this topic meets without the need for exception due to new language in the SOP-3 (2022), that was not fully utilized in the evaluation. The MBK Geotech report was also revised and all 3 geotech due diligence reports are consistent in this approach.

Accepted - closed
10 ULDC 7.4, first paragraph
Paragraph 1 could do with re-structuring because it is confusing as written. It is suggested to use the format similar to that presented in the Kleinfelder and GEI reports where they present the ULDC criteria definition and then state that the levees are considered intermittently loaded.Also, the footnote reference for (HTOL)4 is missing.

ULDC 7.4 1st paragraph was reworded as suggested. And Footnote 4 was added back to the report. (MBK - Rebecca Money, 3/5/25) Accepted - closed 11 ULDC 7.4, American River South Levee, first paragraph. It is recommended that this section start by stating that the American River south levee is considered an intermittently loaded levee A sentence was added at the end of the introduction to indicate both levee are considered intermittently loaded levee. (MBK - Rebecca Money, 3/5/25) The last paragraph states American River north levee. Should this be south levee? Comment remains open. Typo was corrected. Accepted - closed 12 ULDC 7.4, American River South Levee, first paragraph, fourth sentence.

The term 'covers the majority of the levee segments' is ambiguous. Specific details should be presented as to which areas are covered and which are not and why it is considered that the area without analysis are acceptable.He same comment applies to ULDC 7.5.

The phrase "a majority of" was removed from ULDC 7.4 and 7.5 1st paragraphs to provide clarity. (MBK - Rebecca Money, 3/5/25) Accepted - closed 13 ULDC 7.4, American River South Levee, first paragraph, fourth sentence. This section relies on a Statement of Performance provided by USACE, which is not referenced. It should be properly referenced and added to the list of references The USACE letter was added to the reference section and appropriate in text references were added. (MBK - Rebecca Money, 3/5/25) Accepted - closed 14 ULDC 7.4, Sacramento River East Levee, first paragraph. It is recommended that this section start by stating that the Sacramento River east levee is considered an intermittently loaded levee See response to comment 11. Statement was added in introduction section. (MBK - Rebecca Money, 3/5/25) Accepted - closed 15 ULDC 7.4, Sacramento River East Levee, first paragraph, second sentence. Please state who performed the prior analyses. The phrase "by Kleinfelder, GEI, and other consultants" was added to SREL 1st Paragraph, 2nd sentence. (MBK - Rebecca Money, 3/5/25) Accepted - closed 16 ULDC 7.4, Sacramento River East Levee, first paragraph, fourth sentence, 10th line.

The term 'less conservative' appears incorrect. Shouldn't this read 'more conservative'?The sentence/paragraph does not make a statement about the levee geometry used in prior analysis being reviewed and found acceptable based on recent surveys by Psomas.The above comments apply to ULDC 7.5 as well.

Phrase changes from less to more conservative. (MBK - Rebecca Money, 3/5/25)Statements related to geometry are included in Section 7.8. The analysis sections (ULDC 7.4 and 7.5) include evaluations by GEI, Kleinfelder, and MBK to the adequacy and applicability of the analysis performed. All three due diligence reports discuss the analysis geometry under ULDC 7.8. (MBK - Rebecca Money, 3/20/25) Accepted - closed
17 ULDC 7.5, Sacramento River East Levee, first paragraph. It is recommended that this section start by stating that the American River south levee is considered an intermittently loaded levee See response to comment 11. Statement was added in introduction section. (MBK - Rebecca Money, 3/5/25) Accepted - closed 18 ULDC 7.5, American River South Levee, first paragraph, third sentence. This section relies on a Statement of Performance provided by USACE, which is not referenced. It should be properly referenced and added to the list of references The USACE letter was added to the reference section and appropriate in text references were added. (MBK - Rebecca Money, 3/5/25) Accepted - closed 19 ULDC 7.5, Sacramento River East Levee, first paragraph, second sentence. Please state who performed the prior analyses. The phrase "by Kleinfelder, GEI, and other consultants" was added to SREL 1st Paragraph, 2nd sentence. (MBK - Rebecca Money, 3/5/25) Accepted - closed 20 ULDC 7.7, Seismic Vulnerability, next to last paragraph As noted, the Post Earthquake Remediation Plan is in progress and therefore was not provided for review. Please provide this report when available for review. Comment provided for tracking. The PERP is complete and will be provided for you situational awareness. A separate IPE was been involved in the preparation of the PERP and will be providing a letter covering this analysis and documentation. (MBK - Rebecca Money, 3/5/25) PERP and/or supporting information from the other IPE has not yet been provided for review. Comment remains open. PERP to be provided today. Accepted - closed. 21 ULDC 7.8, American River South Levee,
second paragraph, last sentence.

Does MBK's review indicate or show that the American River south levee meets current geometry criteria? If the latter please state as such.

A statement providing this conclusion was already included. No change to the report was made (MBK - Rebecca Money, 3/5/25) Accepted - closed 22 ULDC 7.9, Interfaces and Transitions,
American River South Levee
Has the presence of the Sacramento Landfill been evaluated from a stability and seepage standpoint? It should be noted specifically, especially if ruled out as high ground.

The high ground at the City landfill site did not have specific analysis performed by USACE. But USACE did perform an evaluation and determine that additional mitigation was not needed. This has been added to the MBK geotech due diligence report. (MBK - Rebecca Money, 3/20/25) Accepted - closed
23 ULDC 7.9, Interfaces and Transitions, American River South Levee, Item #2 This states the ARS levee transitions from high ground at Station 1134+00, and back to transitions to the Sacramento Landfill at Station 1157+00, which is also high ground. It is unclear from this description where high ground is. Suggest revising to provide start and end stations of sections defined as high ground.

The text in section 7.9 was updated to be more precise for ARS. (MBK - Rebecca Money, 3/20/25) Accepted - closed 24 ULDC 7.9, Interfaces and Transitions,
American River South Levee, Item #6
Suggest rewording this item. There appears to be a conflict between the statements "It is assumed that these have all been reviewed…by USACE… prior to preparation of the 2014 Statement of Performance Letter" and the following statement that all locations were reviewed and confirmed closed. If they were all reviewed, is the statement about assuming they were checked by USACE, which suggests uncertainty in the evaluation, even required? The text in section 7.9 #6 was updated to be more precise for ARS. (MBK - Rebecca Money, 3/20/25) Accepted - closed 25 ULDC 7.9, Interfaces and Transitions, American River South Levee Figure 2 identifies 5 pumps stations/sumps adjacent to the levee that are not discussed in the report. Are there any penetrations/transitions/changes in closure type (e.g., jet grout) that need to be discussed in this section? No, the item #6 covers those also, where applicable. (MBK - Rebecca Money, 3/20/25) Accepted - closed

SAFCA CERTIFICATION
American River South Basin

REVIEW BY INDEPENDENT PANEL OF EXPERTS (IPC)
1 No. DOCUMENT LOCATION IN DOCUMENT

IPE'S COMMENT
(03/02/2025)

ENGINEER'S RESPONSE
(03/24/2025)
IPE's COMMENT
(04/09/2025)

ENGINEER'S RESPONSE
(04/10/2025)
IPE's FINAL COMMENT / CLOSURE
(04/16/2025)
26 ULDC 7.9, Interfaces and Transitions, American River South Levee Figure 2 identifies 7 pumps stations/sumps adjacent to the levee that are not discussed in the report. Two additional sumps (#132 at Pioneer Reservoir and Railyards pump station) may need to be added to the figure (see prior comment). Are there any penetrations/transitions/changes in closure type (e.g., jet grout) that need to be discussed in this section? Per correspondence with Kleinfelder and GEI, no aditional evaluation of these pump stations is needed beyond the evaluation already described in their due diligence reports. (MBK - Rebecca Money, 3/20/25) Accepted - closed
27 ULDC 10, Erosion, second para., first
sentence. Add the word 'waterside' before levee, unless this isn't technically correct. "waterside" added as suggested to 2nd pargraph, 1st sentence. (MBK - Rebecca Money, 3/5/25) Accepted - closed 28 ULDC 7.10 Erosion, American River,
south, 1st para. what is (117,000 cfs)? Maximum release? 100 year release? 200 year release? 117k cfs is the calculated release for the 1/200 AEP event; 115k cfs is the operational release which is used for both ULDC and FEMA evaluations. The differences in discharge does not have a material impact on the computed water surface elevations that are required to evaluate other ULDC criteria.

Accepted - closed
29 ULDC 7.10 Erosion, American River South, 1st para., tenth line.

The word 'sand' should be added after the word 'poorly graded' as in poorly graded sand to silty sand.Also, this statement needs to be qualified that it has relatively low susceptibility for the modelled velocities.Please cite reference and values for maximum permissible velocities for bare-earth and vegetated flow channels, qualify the definition of bare earth, and check that this includes poorly graded sand, silty sand and silts, as these are typically very susceptible to erosion, with maximum permissible mean channel velocities of 2 fps for fine sand and silty sand per EM 1110-2-1601. The low susceptibility to erosion seems to be at odds with the next sentence about the driving causes for the erosion protection projects.

The word "sand" was added as suggested.The phrase "for the modeled velocities" was added as suggested.The text in the Engineer's report is a generalized summary of the details included in the Erosion Evaluation Report. (MBK - Rebecca Money and Pro Mitra, 3/20/25) Accepted - closed
30 ULDC 7.10 Erosion, American River South, last line This states that American River South meets ULDC 7.10. Depending on the responses to the preceding item, would that need to be qualified to "once the USACE-led erosion protection projects are complete"? The purpose of the USACE erosion projects is not to comply with ULDC, but for hydrologic conditions that are equivalent to a 325-year event. ULDC compliance is not contingent on the completion of the USACE erosion projects, but will further add resiliency to mitigate for erosion at high-water events beyond ULDC.

Accepted - closed
31 ULDC 7.10 Erosion, Sacramento River
East Levee
Please review this section in line with the comments above for ARS. What is the basis of the modeled velocity, are clean sands really not susceptible to erosion, etc. Also, please confirm there have been no past erosion issues within the SREL reach of this certification, and if there were, were they adequately mitigated.

The text in the Engineer's report is a generalized summary of the details included in the Erosion Evaluation Report. Accepted - closed 32 ULDC 7.12 Encroachment, 3rd para., last
sentence
None of the remediations plans were provided for Appendix J. 1) when will the plans be provided for review? 2) For the Encroachment Remediation Plan, the text mentions a "framework" will be provided for the basis of a plan - shouldn't the complete plan be provided? The remediation plans are not required to be reviewed under your scope. They are complete and will be transmitted for you situational awareness. As such, they are a framework for which the land use agency will take and create the actionable plan to implement and track. (MBK - Rebecca Money, 3/5/25) The remediations plans are a required component to achieve ULDC complinace, and therefore, this comment remains open until the situational awareness copies have been provided.

Plans provided yesterday. Accepted - closed.
33 ULDC 7.12 Encroachment, Finding Should the conclusion be similar to Section 7.13 - since an encroachment remediation plans is being prepare, this meets ULDC 7.12 by exception? No, the ULDC conclusion meets criteria with a plan and meets by exception is not necessary as long as there are no "high hazard" encroachments. (MBK - Rebecca Money, 3/5/25) Accepted - closed 34 ULDC 7.14 Floodwalls, Retaining Walls, and Closure Structures, American River South Levee First line of first paragraph state there are no closure structures used for flood control. Need to explain why Mayhew Drain Closure Structure isn't considered a closure structure.Please add a statement explaining why retaining walls are addressed as 'penetrations' similar to that given in the following write up for Sacramento River East Levee. Also, should the referenced '7.13 Penetrations' be '7.12 Encroachments'? Finally, should 'will be ' be replaced with 'are'? Details were added to ARS paragraph 1 to describe the Mayhew Drain Closure Structure.The retaining walls which are part of bridges are covered under Penetrations ULDC 7.13.3 and are described by Mead & Hunt. "will be" changed to "are. (MBK - Rebecca Money, 3/5/25) Accepted - closed
35 ULDC 7.14 Floodwalls, Retaining Walls, and Closure Structures, Sacramento River Levee East Text references Station 1772+50 at Cliffs Marina, but the study limits discussed previously and shown on Figure 2 end at Station 1770+00. Why the discrepancy? The floodwall extends to Station 1772+50, but the ULDC evaluation terminates at 1770+00 where the Beach Lake North Levee ties into SREL. MA-09 often refers to the levee upstream and downstream of Station 1770+00 as the "200-year levee" and "100-year levee", respectively. See Mead & Hunt's Due Diligence Report, Appendix D4.

Accepted - closed
36 ULDC 7.15 Animal Burrows, second paragraph Comments note that references are missing and there is ongoing coordination with the LMAs regarding rodent control. This is a tracking item to confirm no changes are required as a result of the ongoing coordination. The only change was to update the references, the rodent abatement plans have been provided. (MBK - Rebecca Money, 3/5/25) Accepted - closed 37 ULDC 7.16 Levee Vegetation If USACE 2023 gave an unacceptable rating, why it is considered that the system meets ULDC 7.16? Further justification is required.

Current work has been done to resolve the issues noted in the 2023 inspection report, inspection from 2022) and current site visits by MBK did not indicate a vegetation issue exists. Additionally, ULDC does not rely on USACE inspection data. (MBK - Rebecca Money, 3/5/25) The paragraph as written in the Engineers Report does not match the response you have provided. Comment remains open.

Text revised to be similar to O&M letter and correct inconsistency. Accepted - closed 38 ULDC 7.18 Security, second paragraph
Comments note that there is ongoing coordination with ARFCD, MA9, and the City to confirm details in this section. This is a tracking item to confirm no changes are required as a result of the ongoing coordination.

The only change was to update the references, the security plans have been provided. (MBK - Rebecca Money, 3/5/25) Accepted - closed 39 ULDC 7.20 Emergency action, 3rd para. Cite O&M manual O&M reference added. (MBK - Rebecca Money, 3/5/25) Accepted - closed 1 No. DOCUMENT

LOCATION IN

DOCUMENT

IPE'S COMMENT
(03/02/2025) Editorial/Technical ENGINEER'S RESPONSE (03/24/2025) IPE's COMMENT (04/09/2025) ENGINEER'S RESPONSE IPE's FINAL COMMENT / CLOSURE (04/16/2025) 1 Appendix C- MBK H&H Figure 2 Although in Figure 4, suggest showing the levee portion that was taken out of this study at Mayhew Drain Technical Figure 2 revised to include annotation for Mayhew Closure Structure. (MBK - 3/21/25) Accepted - closed 2 4.0 Hydraulic model
Determination of the stage hydrograph boundary condition at the mouth of the American River for the LAR model simulations, was coincident peak discharges used for the two rivers? If so, should state in document Technical
Stage hydrograph for the downstream boundary condition for the American River was based on simulation of the 1/200 AEP American River at Fair Oaks and Sacramento River at Latitude of Sacramento Joint flood centering in the Sacramento River system model and hand off to the Lower American River model. The coincident peak/frequency is based on CVHS event selection procedures documented in USACE (2019). (MBK - 3/21/25) Cite the USACE report and state assumption of coincident peaks Added to Section 3. Accepted - closed 3 4.1. Lower American
River (LAR) Model
The Wood Rogers' model is almost 10 years old. Were there efforts to make sure it was still appropriate to use and were there any adjustments by MBK to the model? Technical Yes, MBK parsed out the Lower American River 1D cross sections and bridges from the Wood Rodgers Sac River System model and ported the model to HECRAS v6.4.1. We then refined the cross sections, top of levee elevations, some bridge pier and low chord elevations, and Mannings n. We re-calibrated the model to the January 1997 flood and verified with the Feb 2017 flood. (MBK - 3/21/25) This information should be placed in the text. Added to Section 4.1 Accepted - closed 4 4.1. Lower American
River (LAR) Model
Since the Wood Rogers' model is almost 10 years old, a different version of HEC-RAS was used back then. Was there any confirmation that there were no significant differences between the old results and the new ones using the current version of HEC-RAS? Technical
Yes, porting the Wood Rodgers HEC-RAS model to HEC RAS v6.4.1 triggered the need to re-calibrate the HEC-RAS model to the January 1997 flood and verified with the Feb 2017 flood event. In addition, refinements to the model geometry described in response 3 triggered a re-calibration. (MBK - 3/21/25) This information should be placed in the text. Added to Section 4.1 Accepted - closed 5 4.1. Lower American
River (LAR) Model What were the associated frequencies of the 117,000 cfs and 85,000 cfs on the American River? Technical 117,000 cfs is approx the 200-year and 85,000 cfs is approx the 20-year based on the regulated frequency curve for Folsom Dam. (MBK - 3/21/25) This information should be placed in the text. Added to Section 4.1 Accepted - closed 6 4.2. Sacramento River
System Model
The Wood Rogers' model is almost 10 years old. Were there efforts to make sure it was still appropriate to use and were there any adjustments by MBK to the model? Looks like MBK added 2-D areas - see next comment Technical
MBK used the Wood Rodgers model geometry as a foundation for the MBK HEC-RAS model. We refined the model geometry to include a HEC-RAS 2D flow area of 1) Fremont Weir area and 2) West Sacramento Southport Levee setback. The addition of these two 2D Flow ares and porting the model to HECRAS v6.4.1 warrented a re-calibration of th model to Dec-Jan 2006 flood event and verification with the January 1997 flood. (MBK - 3/21/25) This information should be placed in the text. Added to Section 4.2 Accepted - closed 7 4.2. Sacramento River
System Model
Since the Wood Rogers' model was almost 10 years ago, it probably did not have 2-D areas. MBK add the 2-D areas and please state why 2-D was used instead of 1-D for these areas. Technical The Wood Rodger's model was developed before completion of the West Sacramento Southport Levee setback project. The project consists of setting back the levee approximately 800 feet and includes inlet and outlets. The use of a 2-D flow area provides a more accurate computation scheme for the hydraulics in this area. (MBK - 3/21/25) This information should be placed in the text. Added to Section 4.2 Accepted - closed 8 4.2. Sacramento River
System Model What was the frequency of the peak discharge of the December 2005 – January 2006 flood event? Technical On the American River, the recorded peak discharge was 37,000 cfs and is less than the 10-year flood based on the regulated frequency curve for Folsom Dam. (MBK - 3/21/25) This information should be placed in the text. Added to Section 4.2 Accepted - closed 9 Table 6 Where is Table 4 and 5? Subsequent table numbering needs to be adjusted. Technical Memo revised to adjust table numbering. (MBK - 3/21/25) Accepted - closed 10 5.3 Superelevation Need units for r = radius of channel center-line curvature Technical Units added to memo. (MBK - 3/21/25) Accepted - closed11 5.6 Updated Hydraulic Model
Did MBK add 2-D areas to the Wood Rogers' model? If so, the statement "no adjustment for updated hydraulic model has been included" is incorrect. Please clarify. Technical Yes, MBK added 2-D areas to the Wood Rodgers model. However, the ULDC "updated hydraulic model" language applies to consideration of adjusting the DWSE. For this effort, we did not make an adjustment to the DWSE . Clarification will be added to Section 5.6. (MBK - 3/21/25) Accepted - closed
12 5.7 Sea Level Rise What was the additional flow depth added to the model's downstream boundary for sea level rise? Technical A 3.68 feet rise at the Golden Gate translates to 2.5 feet rise at the downstream boundary of the HEC-RAS model. (MBK - 3/21/25). This information should be placed in the text. Added to Section 5.7 Accepted - closed 13 APPENDIX A, Figure B-2 The some high water marks are almost a foot off from the computed values. Any explanations why? Technical The high water mark on the Sacramento River at CVFED RM 45.2 is a bad high water mark. The surveyed high water mark is downstream of the recorded gage and is approximately 3.5 feet higher than the recorded peak stage. (MBK - 3/21/25) This information should be placed in the text. Added to Appendix B-2 Accepted - closed 1 Appendix D, Draft ULDC Geotechnical Findings Report, American River South Levee System - Sacramento River East Levee: Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00, GEI Consultants, January 2025 Section 1.7 Water
Surface Elevation Second paragraph, third line - 'entitled' should be 'titled'. The wording has been corrected. (GEI, 3/6/2025) Accepted - closed 2 Section 1.9 Past
performance Second paragraph, fifth line - delete the words 'was but' towards the end of the line. The typo has been corrected. (GEI, 3/6/2025) Accepted - closed 3 Section 2.1.2
First paragraph after Table 2-1 - please confirm the listed average exploration spacing of 40 feet for STA 1080+00 to 1150+00. This seems very close along the levee centerline, and appears to be 5.280 feet divided by the number of borings per mile, which may not be the same as distance between borings. It may also be useful to differentiate total borings vs spacing for borings meeting SOK SOP 2022 criteria. Comment applies to each paragraph after Table 2-1 through 2-4 Technical
The average exploration spacing provided in the discussion was not limited to the explorations on the levee crown. For Station 1080+00 to 1150+00 the average exploration spacing along the levee crown is 155 feet. The paragraphs following Tables 2-1 through 2-4 have been updated to add average spacing for crown explorations. (GEI, 3/6/2025) Accepted - closed
4 Section 2.1.2 Were trench logs from cutoff wall construction considered as a source of subsurface data that was considered as part of this review? Technical Trench logs from cutoff wall construction were not considered in the exploration counts provided in Section 2.2 due to the sufficient density of geotechnical explorations available. (GEI, 3/6/2025) Accepted - closed 5 Section 2.1.2
Conclusion, 2nd paragraph - The conclusions reference subsurface explorations as related to standard of care rather than ULDC criteria, and a few of the explorations spacings (especially landside field) referenced prior are less than 11 borings per mile. Given the sum total of all geotechnical data, does the data for these segments MEET ULDC 7.3 or MEET BY EXCEPTION? Technical
The standard of care notation was included to add support to the finding that ULDC criteria is met. The SPK (2022) guidance for regularly spaced explorations (approximately 11 per mile) includes only the levee crown, landside toe, and waterside toe. All segments meet an average of 11 explorations per mile for the levee crown and landside toe, and the SPK SOP (2022) special case for waterside toe data where the river is immediately adajacent to the levee is discussed. Landside field explorations counts were included in the evaluation discussion but the current SPK SOP states only that "additional borings may be performed landward and waterward of the levee to evaluate the distal seepage conditions" and does not have a regular spacing recommendation. (GEI, 3/6/2025) Accepted - closed
6 Appendix D Levee
Geometry
Levee sections at 1386+50, 1574+30, and 1599+10 have sections where the theoretical levee prism projects out of the waterside levee toe and/or toe scour is present. However, Section 2.4.2 states the required levee geometry fits complete within he 2024 surveyed existing levee prims. These sections should be conformed or justification given as to why these sections meet ULDC criteria. As written, Section 2.4.2 projects a justification for oversteepened slopes, but not differences in levee prism.

Technical
The actual levee embankment encompasses the theoretical levee prism at all sections evaluated. In a few small localized areas, the projected waterside slope of the theoretical levee prism extends beyond the surveyed riverbank slope. However, stability and seepage analyses continue to meet criteria. These localized erosion areas are being addressed within the USACE-led erosion protection projects. Specifically, design for SREL Erosion Contract 3 includes Station 1386+50 in its Site 7 design and Stations 1574+30 and 1599+10 in its Site 9 design. Construction of SREL Erosion Contact 3 is expected to be completed in 2025 and 2026. Discussion of erosion related mitigations has been added to the Section 2.4 text. (GEI, 3/6/2025) Accepted - closed
1 Appendix E, ULDC Geotechnical Findings American River South Levee System, Sacramento River East Levee Stations 1000+00 to 1080+00, 1150+00 to 1185+00, 1206+00 to 1285+75, 14818+00 to 1534+40, and 16+40+00 to 1770, Kleinfelder, January 30, 2025 Section 1.3 background
and Construction
History, first para.

The last line refers to known borrow sources for levee construction materials and references 'relatively clean sand', which doesn't seem correct. Suggest editing sentence to "….there are no known local borrow sources with suitable materials for levee construction.' Technical
Sentence edited to "This is further confirmed as within the land areas of the Sacramento area, there are no known borrow sources with suitable materials for levee construction." (Kleinfelder, 3/24/25) This change does not match the revised text in the March 24, 2025 copy provided for review. The text in the revised report is still confusing. Sentence revised. Accepted - closed.

SUPPORTING REPORTS

REVIEW BY INDEPENDENT PANEL OF EXPERTS (IPC)
1 No. DOCUMENT

LOCATION IN

DOCUMENT

IPE'S COMMENT
(03/02/2025) Editorial/Technical ENGINEER'S RESPONSE (03/24/2025) IPE's COMMENT (04/09/2025) ENGINEER'S RESPONSE IPE's FINAL COMMENT / CLOSURE (04/16/2025) 2 Section 1.4
Methodology, first para.,
page 5
Is the text is trying to say that all WSE's previously used for analysis were higher than the new 200-year DWSE and HTOL or only the new HTOL WSE? Either way, suggest deleting the word 'highest' and replacing with the word 'lowest', as in the new HTOL is lower than the lowest HTOL previously used for analysis.

Technical Revised language in the paragraph to clarify the new WSEs are below the previous WSEs which met geotechnical criteria. (Kleinfelder, 3/24/25) Accepted - closed 3 Section 2.3.1 ULDC 7.5
The text references a dewatering system along the depressed section of I-5. Are there monitoring wells associated with this system? Are those records accessible from Caltrans? While not necessarily specific to this report, it is important that these details area captured somewhere.

Technical
The monitoring wells and pressure sensors are a part of the monitoring system. The first paragraph of Section 2.3.1 has been revised. (Kleinfelder, 3/24/25)Records provided by Caltrans were reviewed by Kleinfelder as a part of the analysis performed and documented in Appendix E of the 2016 ULDC Geotechnical Summary Report.

Accepted - closed
Note the revised text should define "RSS" and it appears the word "through" is not needed in the last sentence of the first paragraph. FYI - no backcheck required.

Text revised. Accepted - closed.
4 Section 2.4 ULDC 7.7 When is the Remediation Plan anticipated to be finished? Technical PERP is anticipated to be finalized for ARSL at the same time as this report. (Kleinfelder, 3/24/25) Please provide the Post Earthquake Remediation Plan for Review (at least a "situational awareness" copy) so the IPE can confirm the work is complete and meets ULDC criteria.

PERP provided. Accepted - closed.
5 Section 2.5, ULDC 7.8,
Levee geometry
Levee sections at 1021+70, 1026+40, 1027+90 (wall location), and 1493+70 have sections where the theoretical levee prism projects out of the waterside levee toe and/or toe scour is present. However, Section 2.5 states the required levee geometry fits complete within he 2024 surveyed existing levee prims. These please comment as to why these sections meet ULDC criteria.

Technical
Sections 1021+70, 1026+40, and 1027+90 are areas of high ground. The survey sections are limited due to property access. Section 1493+70 is considered to meet ULDC 7.8 Geometry since the critical cross sections within the analytical reach meet landside and stability. First paragraph of page 38 was updated to note the area of high ground. (Kleinfelder, 3/24/25) Accepted - closed
6 Section 2.6.2.4 Retaining
Wall Encroachments,
first para.

Please clarify what is meant by "..because they may increase the elevation of the landside toe…' Technical First paragraph of Section 2.6.2.4 revised to, "Retaining walls are considered an interface because they encroach upon and reduce the levee prism. " (Kleinfelder, 3/24/25) Accepted - closed
1 Appendix F, Geotechnical Due Diligence Report - Urban Levee Design Criteria American River South Levee Station 1000+00 to 1635+50, MBK January 31, 2025 Criteria Is the third bullet the updated version of the fourth bullet? If so please deleted the fourth bullet. Technical 4th bullet was removed. (MBK - Rebecca Money, 3/6/25) Accepted - closed 2 ULDC 7.3, second para.

Please qualify what your 'cursory' review was. It needs to have been sufficient to be confident in your determination of compliance. Use of the word 'indicate' in the penultimate line doesn't seem certain enough for this type of determination. Your review either shows it meets or it doesn't in your consideration.

Technical Text was revised to provide more certainty in the review and conclusion. (MBK - Rebecca Money, 3/6/25) Accepted - closed 3 ULDC 7.4, and ULDC 7.5
Second para., third and
fourth sentences.

The third sentence does not demonstrate with any confidence how the statement in the fourth sentence was arrived at. The reader needs to understand how the review was performed in order to determine the coverage of analyses relative to the levee segments reviewed by MBK .

Technical Text was revised to provide more certainty in the review and conclusion. (MBK - Rebecca Money, 3/6/25) Accepted - closed 4 ULDC 7.4, Appendix E
In the table in Appendix E, the 'Station' column is largely incomplete. When values are provided, they don't relate to the Stationing used in the report text (1000+00 to 1635+50). To assess coverage of previously performed analysis and results thereof, there needs to be stationing information even if it is approximate.

Technical
Unfortunately the stationing and analysis locations were not consistent and often didn't include plan views showing where the analysis was for me to deduce a common stationing. No changes are planning for Table in Appendix E. (MBK - Rebecca Money, 3/6/25) Accepted - closed
Consider adding a footnote to explain lack and inconsistency of stationing
5 APPROACH and ULDC

7.4 and ULDC 7.5
Second para., third and
fourth sentences.

In the Approach, it states, "Step 3: Confirm provided documentation in Steps 1 and 2 covers all reached covered in this letter." However, ULDC 7.4 and 7.5 state, "The analyses were not reviewed in detail and a review was not performed to confirm that every reach was evaluated due to the Statement of Performance provided by USACE." These two statements seem at odds and additional discussion is required to understand how the approach steps were followed.

Technical Text was revised to provide more certainty in the review and conclusion. (MBK - Rebecca Money, 3/6/25) Accepted - closed 6 ULDC 7.4, Second para.,
Post Earthquake
Remediation Plan
Has this document been prepared or is it in preparation? Other documents reviewed suggest it is in preparation. Assume it will be complete by the time certification documents are finalized. Technical The PERP is being finalized now and will be part of the final package. (MBK - Rebecca Money, 3/6/25) Remains open until PERP is provided for review. PERP provided. Accepted - closed. 7 ULDC 7.9, Interfaces and
Transitions, Item #6
Suggest rewording this item. There appears to be a conflict between the statements "It is assumed that these have all been reviewed…by USACE… prior to preparation of the 2014 Statement of Performance Letter" and the following statement that all locations were reviewed and confirmed closed. If they were all reviewed, is the statement about assuming they were checked by USACE, which suggests uncertainty in the evaluation, even required? Similar comment is listed in the Engineer's Report.

Technical 6th bullet was revised to provide more certainty in the review and conclusion. (MBK - Rebecca Money, 3/6/25) Accepted - closed 1 Appendix G, MBK Levee O&M Review Page 2, 2nd para., 5th sentence This sentence states there is "minimal" vegetation within 15 feet of the levee landside toe. However, for ARS, there appears to be a significant amount of vegetation at the landside toe, especially in residential areas where fences are at the toe. Similarly, there is a significant amount of vegetation along the waterside slopes for SREL. We suggest this characterization be reviewed. This also seems to be at odds with the statement in Paragraph 5 that USACE has found vegetation unacceptable but not high hazard.

Technical Text was revised to provide more discussion of vegetation. (MBK - Rebecca Money, 3/6/25) Accepted - closed 1 Appendix I, AMERICAN RIVER SOUTH LEVEE SYSTEM Due Diligence Review for ULDC & FEMA Certification, Mead & Hunt, January 31, 2025 Exhibit 3B, Table
Summary of
Penetrations and
Associated Structures
Several pipes in the tables are noted "Needs Data" in the pipe size and material columns, and a larger number are noted as "Not Needed". Can you please explain, in general, how that assessments were completed where this information is missing/not available? Technical
The term "Needs Data" was being used for pending data that was not available at the time of publishing the draft. These gaps have been filled as needed prior to final report.The term "Not Needed" is used for inputs that are not critical to the analysis being conducted. (Mead & Hunt, 3/24/25) Accepted - closed.

For tracking purposes, the files provided for backcheck labeled the M&H report as Appendix H, but it appears this should be Appendix I, consistent with the TOC in the Engineer's Report. No change required, just documenting what was reviewed.
2 APPENDIX B. Penetration
Exceptions Work Plan
Technical Memorandum,
Section 2.2, List of ASLS
Exceptions
The third sentence states, "A separate list of penetrations flagged for exceeding useful life will be provided in the next draft of this Technical Memorandum, due to voluminous data that must be further vetted." When is the completed drafted expected to be provided for review? Technical The data has been summarized in the updated draft of the report. (Mead & Hunt, 3/24/25) Accepted - closed 3 APPENDIX B. Penetration
Exceptions Work Plan
Technical Memorandum,
Attachment 1 and
Attachment 3
The last section in Attachment a, Flag for Lack of Inspection Data, states "The following penetrations lack documentation", but no penetrations are listed. This section appears incomplete. Similarly, Attachment 3 states "Pending further progress on data collection". Similar to above, when is a revised draft to be provided for review.

Technical
The "Needs Data" was a placeholder and has been updated. While there are some specific needs, generally for significant penetrations there is sufficient data to indicate these penetrations would not be considered potentially High Hazard, thereby not requiring a full engineering assessment.The "Not Needed" is used for data that is not required for full engineering assessment (e.g. related structures, abandoned pipes, non-penetrating pipes, shallow landscaping pipes, etc.). Where "Not Needed" is used for conduit penetrations size/materials these are shallow (above DWSE) small diameter conduits. Pipes size/material has been addressed where necessary for completion of analysis. (Mead & Hunt, 3/24/25) Although the response does not seem to directly address the IPE comment, the report has been updated with the missing information and timeframe for obtaining the information. Accepted - closed. 1 Appendix C.

American River South ULDC
Design Water Surface Elevation
Profiles - MBK Engineers
Water Resources Flood Control Water Rights

TECHNICAL MEMORANDUM
DATE: April 9, 2025
PREPARED FOR: SAFCA
PREPARED BY: Don Trieu, P.E. SUBJECT: American River South Levee System - Determination of the Urban Levee Design Criteria Design Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 2 2 Acronyms and Abbreviations
1-D one dimensional
2-D two dimensional
AEP annual exceedance probability
ARS American River South
cfs cubic feet per second
CVFED Central Valley Floodplain Evaluation and Delineation CVFPP Central Valley Flood Protection Plan
CVHS Central Valley Hydrology Study
DWR California Department of Water Resources
DWSE Design Water Surface Elevation
FEMA Federal Emergency Management Agency
HTOL Hydraulic Top of Levee
LAR Lower American River
MBK MBK Engineers
MTOL Minimum Top of Levee
NAS North Area Streams
NAVD88 North American Vertical Datum of 1988
NEMDC Natomas East Main Drainage Canal
RM River Mile
SAFCA Sacramento Area Flood Control Agency
SNRR Sacramento Northern Railroad
SVRP Seismic Vulnerability Restoration Profile
ULDC Urban Levee Design Criteria
ULOP Urban Level of Flood Protection
UPRR Union Pacific Railroad
USACE U.S. Army Corps of Engineers
WSE water surface elevation

1. Purpose
The Sacramento Area Flood Control Agency (SAFCA) is in the process of evaluating the levees within its jurisdictional boundaries for compliance with the State of California’s Urban Levee Design Criteria (ULDC) (DWR, 2012). This technical memorandum provides documentation of the determination of the hydraulic parameters listed in Table 1, which are necessary for the ULDC compliance evaluation of the American River South (ARS) levee system.

All elevations are referenced to the North American Vertical Datum of 1988 (NAVD88).

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 3 Table 1. ULDC Hydraulic Parameters
Parameter ULDC Definition
ULDC 7.1 Design Water Surface Elevation (DWSE) Median 200-year (1/200 annual exceedance probability (AEP)) water surface elevation (WSE)
ULDC 7.2 Minimum Top of Levee (MTOL)
DWSE plus the higher of
• 3 feet, or
• wind setup and wave runup
Hydraulic Top of Levee (HTOL) to support ULDC

7.4, 7.5, 7.12, and 7.13
The lower of
• DWSE plus 3 feet, or
• Median 500-year (1/500 AEP) WSE
Seismic Vulnerability Restoration Profile (SVRP) to
support ULDC 7.7
10-year (1/10 AEP) water surface elevation plus the higher of • 3 feet, or
• wind setup and wave runup

2. Study Area
The American River South (ARS) levee system protects the floodplain bounded on the north by the American River, on the west by the Sacramento River, on the south by Morrison Creek, and on the east by high ground (see Figure 1). The ULDC profiles for the Morrison Creek north levee, also referred to as the Beach Lake north levee, are covered in a separate report (MBK, 2024). The levee segments in the ARS levee system covered in this report are summarized in Table 2. Levee stationing for the American River South Levee is shown in Figure 2. Levee stationing for the north end of the Sacramento River East Levee is shown in Figure 2, with the remainder shown in Figure 3.

It should be noted that for the American River South Levee, the reach of levee between stations 1555+50 and 1591+40 was removed from the system by the completion in 2009 of the Mayhew Drain closure structure, shown in Figure 4.

Table 2. American River South Levee System
Levee Segment Length (feet) Upstream Limit Downstream Limit American River South Levee 60,000 High ground near Gristmill Recreation Area
Sacramento River East Levee
Sacramento River East Levee 77,000 American River South Levee Beach Lake north levee SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 4 Figure 1. American River South Levee System.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 5 Figure 2. Levee Stationing for the American River South Levee and North End of Sacramento River East Levee.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 6 Figure 3. Levee Stationing for the South Portion of the Sacramento River East Levee.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 7 Figure 4. Mayhew Drain Closure Structure.

3. Hydrology
Central Valley Hydrology Study (CVHS) procedures and hydrologic data were used in this analysis. The CVHS was commissioned by DWR and prepared by the USACE (USACE, 2015). For the Sacramento River and San Joaquin River basins, the CVHS defines a procedure in which a scaled flood event with a pattern based on a historical flood event is selected to represent the flood of a specific frequency at a specific location, or centering. A CVHS event selection for a flood with a joint centering of the American River at Fair Oaks and Sacramento River at latitude of Sacramento developed by USACE (USACE, 2019) was used for the determination of the ARS ULDC profiles. The joint centering required USACE to adjust the coincident flow on the Sacramento River to match the annual chance exceedance associated with the primary flow on the American River (USACE, 2019). The CVHS flood events for the three flood frequencies needed for the ULDC profiles are summarized in Table 3.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 8 Table 3. CVHS Flood Events For American River at Fair Oaks and Sacramento River at Latitude of Sacramento Joint Flood Centering
Flood
Frequency
(AEP)
CVHS Flood Event
Peak Flow (cfs)
American River below
Folsom Dam
Sacramento River below
American River
1/10 1986-55% with 40% on American River 74,300 94,900
1/200 1986-110% with 125% on American River 116,900 107,500 1/500 1986-100% with 176% on American River 298,500 123,800

4. Hydraulic Model
Two HEC-RAS1 hydraulic models were used to determine the ULDC water surface elevations for the American River South Levee System:

1. Lower American River (LAR) model

2. Sacramento River system model
The LAR model was used for the determination of the ULDC profiles for the American River South Levee.

The Sacramento River system model was used for the determination of the ULDC profiles for the Sacramento River East Levee, and simulated with the each of the flood frequency and centering shown in Table 3 to determine the stage hydrograph boundary condition at the mouth of the American River for the LAR model simulations.

4.1. Lower American River (LAR) Model
The LAR model is a 1-D model consisting of the American River from Nimbus Dam (Lake Natoma) to the Sacramento River, and the NEMDC from Arcade Creek to the Sacramento River. It was adapted by MBK from the Sacramento River Watershed HEC-RAS model developed for the DWR Central Valley Floodplain Evaluation and Delineation (CVFED) project (Wood Rodgers, 2015). MBK parsed out the Lower American River from the CVFED model and ported it into HEC-RAS v6.4.1. Minor refinements to the model geometry were made to refine cross section location, top of levee elevations and bridge geometry. These refinements warranted a re-calibration of the hydraulic model A schematic of the LAR model is provided in Figure 5.
1 HEC-RAS is software developed by the USACE Hydrologic Engineering Center for the purpose of performing one-dimensional (1-D) and two-dimensional (2-D) hydraulic calculations for a full network of natural and constructed channels (USACE, 2023).

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 9 Figure 5. Lower American River HEC-RAS Model Schematic
The LAR model was calibrated using the January 1997 flood event, which had a peak American River flow of about 117,000 cfs (~1/200 AEP). On February 10, 2017, when the flow in the lower American River was about 85,000 cfs (~1/20 AEP), cbec Eco-engineering surveyed the water surface elevation at several locations. A simulation of the February 10, 2017, conditions was made to verify the model calibration. The results of the calibration and verification simulations are provided in Appendix A.

The LAR model was used to compute the ULDC WSE’s for the American River South Levee.

4.2. Sacramento River System Model
The Sacramento River System model is a combined 1-D and 2-D model of the Sacramento River and major tributaries and distributaries from Colusa at the upstream end to Suisun Bay at the downstream end. The model was developed by MBK from the Sacramento River Watershed HEC-RAS model developed for the DWR CVFED program (Wood Rodgers, 2015). MBK used the CVFED model as a foundation for the MBK HEC-RAS model. The MBK model geometry was refined to add 2-D flows areas then ported to HECRAS v6.4.1. These model geometry refinements and porting to HEC-RAS v6.4.1 required re-calibration of the MBK HEC-RAS model.

A schematic of the model is provided in Figure 6.The model is primarily made up of 1-D elements, supplemented with 2-D flow areas for the Fremont Weir area (Figure 7) and the Southport Levee Improved Project area on the Sacramento River about 2.5 miles south of the American River (Figure 8). 2- D flow areas were added at these two locations as they are areas of complex hydraulic flow patterns which are better simulated using a 2-D computation scheme.

The model was recalibrated using the December 2005 – January 2006 flood event (~1/10 AEP) and verified with the January 1997 flood event. Comparisons of observed and computed stages and flows in the ARS Sacramento River East Levee reach are provided in Appendix B.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 10 Figure 6. Sacramento River System HEC-RAS Model Schematic.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 11

5. Urban Levee Design Criteria (ULDC)
Section 7.1 of the ULDC allows for two options for the determination of the DWSE. The first option is the Federal Emergency Management Agency (FEMA) Approach, in which the DWSE is computed deterministically with a hydraulic model. The second option is the U.S. Army Corps of Engineers Approach, which incorporates uncertainty into the determination of the DWSE. The approach selected for this analysis was the FEMA Approach, due to its application and results being more straightforward and economical.

The ULDC defines the DWSE as the “200-year stage or water level used to design a levee or floodwall”.

Section 7.1.1 of the ULDC specifies that the hydraulic modeling used to determine the DWSE must consider the following:
• Upstream, downstream, and nearby levees and floodwalls protecting urban areas are assumed to be raised to the median 200-year water surface elevation plus 3 feet and not allowed to breach, even if overtopped. Overtopping flows are assumed to leave the channel and remain in the 200- year floodplain.

Figure 7. Fremont Weir 2-D flow area Figure 8. Southport 2-D flow area SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 12 • All project levees and floodwalls are to be modeled to incorporate a minimum crown elevation equal to the authorized (usually the 1955/1957) USACE design profiles – this affects nonurbanized areas for the most part – all such levees and floodwalls are to be allowed to overtop, act as weirs, and not breach for floods up to and including the median 500-year flood.

Overtopping flows are assumed to leave the channel and remain in the 200-year floodplain. • Non-project levees and floodwalls in non-urbanized areas in the region, to the extent they may affect the DWSE, are to be modeled at their existing or authorized height, whichever is higher, and to act as weirs without breaching if overtopped.
• Debris loading on bridges must be considered. Bridges with less than 3 feet of clearance above the DWSE may experience extraordinary debris loading that must be evaluated in addition to typical pier/bent debris loading. The evaluation should include historic and potential debris transport in the stream, an analysis of loading on the bridge, and analysis of backwater impacts on the DWSE in the vicinity of the bridge.

Section 7.1.3 of the ULDC requires adjustments to the DWSE for the effects of superelevation, when applicable. Superelevation is a tilting of the water surface, which may occur as water flows through a bend in the channel. Computational methods for determining superelevation adjustments are in the USACE Engineering Manual 1110-2-1601.

Section 7.1.3 of the ULDC also states that the “…the civil engineer should consider increasing the DWSE to account for the potential increases in water surface associated with climate change, updated hydrology, updated hydraulic models, and sea level rise”. This statement implies that adjustment for sea level rise is optional; however, Section 7.19 of the ULDC states, “the effects of sea level rise are to be estimated and addressed for the duration during which a Finding that the urban level of flood protection exists may be valid”. Based on the second statement, sea level rise adjustment appears to be mandatory.

Additionally, Section 7.1.3 of the ULDC states:
“[T]he civil engineer also needs to address two other situations: (1) whether upstream levee or floodwall breaches could produce overland flows that would reach the area protected by the levee system or increase the water surface elevation along the levee system, and (2) whether flooding in a nearby leveed area could fill that area and breach a nearby levee or floodwall, returning flow to the stream and increasing the DWSE for a portion of the levee system".

Neither of these conditions are applicable to the study area, and therefore were not evaluated.

The following sections address the requirements in the ULDC and discuss the application of each requirement for the American River South Levee System.

5.1 Levees
As per the ULDC, all urban levees were assumed to have a minimum top elevation of the median 200-year water surface elevation plus 3 feet. All non-urban State-Federal Project levees were assumed to have a minimum crown elevation equal to the authorized USACE design profiles.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 13

5.2 Debris Loading
The ULDC specifies that debris loading on bridges must be considered, and that “bridges with less than 3 feet of clearance above the DWSE may experience extraordinary debris loading that must be evaluated in addition to typical pier/bent debris loading”.

Bridge pier debris are applied in accordance with guidelines provided in a July 2014 letter (USACE, 2014), sent by USACE to the California Central Valley Flood Protection Board in order to clarify the level of screening and analysis that should be included on encroachment permit applications that are sent to the USACE for review. A copy of the letter is provided in Appendix C. Included in the letter was guidance for modeling debris build-up. Based on this guidance, under the ULDC “typical” debris loading condition, the hydraulic analysis included floating debris with a width equal to double the pier width, and a depth of 2 feet below the water surface. Under the ULDC “extraordinary” debris loading condition, floating debris with a depth of 2 feet below the water surface were modeled for the full width with the “extraordinary” condition.

Debris were not applied to bridges in the model upstream of the levee reaches, as debris on these bridges would have no effect on the water surface elevation in the levee reaches.

A summary of the bridge pier debris conditions included in the hydraulic analysis is provided in Table 4.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 14 Table 4. Bridge Pier Debris Loading
River Levee
Station Bridge
Debris Loading Condition1
200-yr 500-yr
American River 2 Bike Trail bridge t E
1467+80 Watt Ave t E
1386+60 Howe Ave t E
1347+10 Guy West t E
1320+30 H St t E
1204+00 Cap City Fwy t t
1195+20 RR t E
1118+10 RR t E
1111+90 Bike Trail t E
1100+60 CA-160 E t mix
1099+20 CA-160 W t mix
1013+00 I-5 t mix
1010+00 Jibboom St mix E
Sacramento River 1039+00 I St E E
1060+50 Tower Bridge t E
1103+20 US 50 t t
1215+30 Freeport t E
3 Paintersville t t
3 Walnut Grove t E
3 Isleton t mix
3 Rio Vista t t
Steamboat Slough 3 CA-160 t E
Sutter Slough 3 South River Rd E E
Miner Slough 3 CA-84 t t
Geogiana Slough 3Isleton Rd E E
3 Tyler Island t t
Threemile Slough 3 CA-160 t E
1 t = typical; E = extraordinary; mix = combination of t and E. 2 Upstream of American River South Levee.
3 Downstream of Sacramento River East Levee.

5.3 Superelevation
Superelevation is a tilting of the water surface that occurs on the outside of a river bend. The ULDC notes that, “on the outside of a bend, the superelevation needs to be added to the DWSE”. The superelevation adjustment, per USACE Engineer Manual 1110-2-1416, River Hydraulics, is specific to 1-D hydraulic modeling. Superelevation adjustments were applied at three locations on the American River South Levee and at one location on the Sacramento River East Levee (Figure 9):
• American River, levee station 1340+00 to 1362+00
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 15 • American River, levee station 1250+00 to 1257+00
• American River, levee station 1125+00 to 1150+00
• Sacramento River, levee station 1660+00 to 1680+00
As recommended in the ULDC, computational methods in USACE Engineering Manual 1110-2-1601 were used to compute superelevation. Superelevation is computed with the following equation:
y = CV2W/gr
where
y = superelevation (feet)
C = coefficient = 0.5 (tranquil, or subcritical, flow)
V = mean channel velocity (feet/second)
W = channel width at elevation of center-line water surface (feet) g = acceleration of gravity (32.2 feet/second2)
r = radius of channel center-line curvature (feet)
Figure 9. Superelevation Evaluation Locations
The computed superelevation and corresponding parameters are summarized in Table 5.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 16 Table 5. Superelevation
Location
r
(feet)
1/200 AEP 1/500 AEP
V
(feet/
second)
W
(feet)
Superelevation
(feet)
V
(feet/
second)
W
(feet)
Superelevation
(feet)
American River,
levee station 1362+00
to 1340+00
1700 10.6–11.4 251-262 0.26–0.31 13.8–15.0 251-262 0.45-0.53 American River,
levee station 1257+00
to 1250+00
800 8.8 259 0.39 10.1 259 0.51
American River,
levee station 1150+00
to 1125+00
2,300 5.9-6.8 335-448 0.11 7.3-8.4 335-448 0.16
Sacramento River,
levee station 1660+00
to 1680+00
2,300 4.5 649 0.09 4.9 649 0.11

5.4 Climate Change
The effects of climate change on extreme precipitation events in the Central Valley are being studied, but there is no indication of what the outcome of that work will be. Therefore, the hydrology used in this analysis has not been adjusted for the effects of climate change.

5.5 Updated Hydrology
This analysis makes use of the most recent accepted hydrologic data for the Study Area, which was developed as part of the Central Valley Hydrology Study, as noted in Section 4 of this report.

5.6 Updated Hydraulic Model
The hydraulic model used for this analysis was developed from the most current available data. Due to the calibration process, an updated hydraulic model would not be expected to have a substantial effect on the computed results unless significant physical changes have occurred in the modeled system. Since no significant physical changes have occurred since the data used for the model development was collected, no adjustment to the DWSE for updated hydraulic model has been included.

5.7 Sea Level Rise
The ULDC notes that, “the effects of sea level rise are to be estimated and addressed for the duration during which a Finding that the urban level of flood protection exists may be valid”. The duration of finding proposed for the subject project is 20 years.

The analysis assumed a sea level rise of 3.68 feet at the San Francisco Golden Gate which translates to approximately 2.5 feet rise at the downstream boundary conditions of the Sacramento River System model. This is the 50-year sea level rise projection determined by DWR for the 2022 update of the Central Valley Flood Protection Plan (CVFPP) (DWR, 2022). Being that the duration of the Urban Level of Protection finding is 20 years with periodic reviews every 5 years, the use of a 50-year projection is a conservative assumption. The effects of this sea level rise were applied at the downstream boundaries of SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 17 the Sacramento River systemwide hydraulic model simulations, which were used to determine the downstream boundary conditions for the LAR model.

6. Computed ULDC Hydraulic Parameters
The following sections present the computed ULDC hydraulic parameters that were described in Section 1 of this technical memorandum:
• Design Water Surface Elevation (DWSE)
• Minimum Top of Levee (MTOL)
• Hydraulic Top of Levee (HTOL)
• Seismic Vulnerability Restoration Profile

6.1 Design Water Surface Elevation (DWSE)
The ULDC defines the DWSE as “[the] median 200-year water surface elevation”, with adjustments for the following factors:
• Bridge pier debris loading
• Superelevation
• Sea level rise
Debris loading and sea level rise are accounted for in the hydraulic model simulations, as described in Sections 5.2 and 5.7. As noted in Section 5.3, the superelevation adjustment was applied at three locations on the American River South Levee and one location on the Sacramento River East Levee.

Figures 10 and 11 show profile plots of the computed DWSE for the American River South Levee and the Sacramento River East Levee, respectively. Levee crest profiles are included on the profile plots.

Tabulations of the DWSE profiles are provided in Appendix D.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 18 Figure 10. ULDC DWSE Profile, American River South Levee Figure 11. ULDC DWSE Profile, Sacramento River East Levee I Street bridge Tower Bridge Pioneer Memorial Bridge Sutterville Rd.

Freeport Bridge
Beach Lake Levee
20 25
30 35
40 45
1000+00 1100+00 1200+00 1300+00 1400+00 1500+00 1600+00 1700+00 1800+00 Elevation (feet, NAVD88)
Levee Station (feet)
Top of Levee [1]

ULDC DWSE
[1] Source: Psomas survey, 2024-2025
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 19

6.2 Minimum Top of Levee (MTOL)
The ULDC defines the MTOL as the higher of the DWSE plus 3 feet, or the DWSE plus the computed wind setup and wave runup. Wind setup and wave runup (wind and wave) for the ARS levee system has been computed by Mead & Hunt (Mead & Hunt, 2024). The maximum computed wind and wave is less than 3.0 feet for all the American River South Levee, and for the Sacramento River East Levee upstream of station 1654+00. Maximum wind and wave was computed to be 3.5 feet at station 1660+00 of the Sacramento River East Levee, and 3.1 feet at about station 1710+00. The wind and wave was applied to the MTOL by tapering from 3.0 feet at station 1654+00 to 3.5 feet at station 1660+00, then tapering back down to 3.1 feet at station 1710+00, and continuing with 3.1 feet to the end of the Sacramento River East Levee at station 1770+00. Figures 12 and 13 show profile plots of the MTOL for the American River South Levee and the Sacramento River East Levee, respectively. Tabulations of the MTOL profiles are provided in Appendix D.

Figure 12. ULDC MTOL Profile, American River South Levee SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 20 Figure 13. ULDC MTOL Profile, Sacramento River East Levee

6.3. Hydraulic Top of Levee (HTOL)
The ULDC defines the HTOL as the lower of the DWSE plus 3 feet, or the median 500-year WSE. Figures 14 and 15 show profile plots of the HTOL for the American River South Levee and the Sacramento River East Levee, respectively. For reference, the DWSE plus 3 feet and 500-year WSE profiles are also shown.

Tabulations of the HTOL profiles are provided in Appendix D.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 21 Figure 14. ULDC HTOL Profile, American River South Levee Figure 15. ULDC HTOL Profile, Sacramento River East Levee I Street bridge Tower Bridge Pioneer Memorial Bridge Sutterville Rd.

Freeport BridgeBeach Lake Levee
20 25
30 35
40 45
1000+00 1100+00 1200+00 1300+00 1400+00 1500+00 1600+00 1700+00 1800+00 Elevation (feet, NAVD88)
Levee Station (feet)
Top of Levee [1]
DWSE + 3 feet
500-year WSE

ULDC HTOL
[1] Source: Psomas survey, 2024-2025
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 22

6.4 Seismic Vulnerability Restoration Profile (SVRP)
The ULDC specifies that if there is the potential for levee damage due to a seismic event, a plan needs to be in place to “restore grade and dimensions for at least 10-year WSE plus 3 feet of freeboard or higher for wind setup and wave runup within 8 weeks”. This profile is referred to herein as the Seismic Vulnerability Restoration Profile (SVRP). As described in Section 6.2, the wind setup and wave runup exceeded 3 feet on the Sacramento River East Levee downstream of station 1654+00. Seismic vulnerability restoration profiles for the American River South Levee and Sacramento River East Levee are provided in Figures 16 and 17, respectively. Tabulations of the seismic vulnerability restoration profiles are provided in Appendix D.

Figure 16. ULDC SVRP Profile, American River South Levee SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 23 Figure 17. ULDC SVRP Profile, Sacramento River East Levee I Street bridge Tower Bridge Pioneer Memorial Bridge
Sutterville Rd.

Freeport BridgeBeach Lake Levee
20 25
30 35
40 45
1000+00 1100+00 1200+00 1300+00 1400+00 1500+00 1600+00 1700+00 1800+00 Elevation (feet, NAVD88)
Levee Station (feet)
Top of Levee [1]

ULDC SVRP
[1] Source: Psomas survey, 2024-2025
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 24 References
DWR. (2012). Urban Levee Design Criteria. May 2012.

DWR. (2022). 2022 CVFPP Update - Technical Analyses Summary Report. November 2022.

MBK. (2024). Beach Lake North Levee – Determination of the Urban Levee Design Criteria Design Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee - DRAFT.

December 13, 2024.

Mead & Hunt. (2024). Wind-Wave Analysis for American River South and Sacramento River East Levee Systems. December 5, 2024.

USACE. (2014). Letter from US Army Corps of Engineers, Sacramento District, to Central Valley Flood Protection Board. July 21, 2014.

USACE. (2015). Central Valley Hydrology Study. November 29, 2015.

USACE. (2019). Memorandum for Record, Subject: CVHS Hydrograph Package for HEC-RAS Model Inputs. February 20, 2019.

USACE. (2020). Hydrology Technical Memorandum for Developing WRDA 2016 Water Surface Profiles.

April 10, 2020.

USACE. (2023). HEC-RAS User's Manual. Retrieved from
https://www.hec.usace.army.mil/confluence/rasdocs/rasum/6.4 Wood Rodgers. (2015). Refine/Calibrate Combined Sacramento River and San Joaquin River Systems, Sacramento River System Study Area Report. May 29, 2015.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL

APPENDIX A
Hydraulic Model Calibration
Lower American River Model
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page A-1 Simulation Event Peak American River flow
Calibration January 1997 flow 117,000 cfs
Verification February 10, 2017 ~85,000 cfs
Figure A-1. Calibration, January 1997, Maximum Water Surface Elevation Profile with Surveyed High Water Marks, American River river miles 10 to 23 (Mayhew Drain to Nimbus Dam) Figure A-2. Calibration, January 1997, Maximum Water Surface Elevation Profile with Surveyed High Water Marks, American River river miles 0 to 11 (Sacramento River to Mayhew Drain) Figure A-3. Verification, February 10, 2017, Maximum Water Surface Elevation Profile with Surveyed Water Surface Elevation, American River river miles 10 to 23 (Mayhew Drain to Nimbus Dam)
Figure A-4. Verification, February 10, 2017, Maximum Water Surface Elevation Profile with Surveyed Water Surface Elevation, American River river miles 0 to 11 (Sacramento River to Mayhew Drain)

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page A-2 Figure A-1. Calibration, January 1997, Maximum Water Surface Elevation Profile with Surveyed High Water Marks, American River, river miles 10 to 23 (Mayhew Drain to Nimbus Dam) Figure A-2. Calibration, January 1997, Maximum Water Surface Elevation Profile with Surveyed High Water Marks, American River, river miles 0 to 11 (Sacramento River to Mayhew Drain) SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page A-3 Figure A-3. Verification, February 10, 2017, Maximum Water Surface Elevation Profile with Surveyed Water Surface Elevations, American River, river miles 10 to 23 (Mayhew Drain to Nimbus Dam) Figure A-4. Verification, February 10, 2017, Maximum Water Surface Elevation Profile with Surveyed Water Surface Elevations, American River, river miles 0 to 11 (Sacramento River to Mayhew Drain) SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL

APPENDIX B
Hydraulic Model Calibration and Verification
Sacramento River System Model
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page B-1 Observed data in the ARS Sacramento River reach is available at the two stream gages shown in Figure B1. A summary comparison of the observed and computed calibration event peak stages and flows at the gages is provided in Table B-1. Additionally, several high-water marks from the calibration event and verification event were identified in the levee reach and surveyed by MBK Engineers (January 1997 flood event) and the California Department of Water Resources (Dec-Jan 2006 flood event). A profile plot comparing the computed maximum water surface elevation along the ARS Sacramento River East Levee and the surveyed high-water marks and measured gage peaks is provided in Figure B-2 and Figure B-3.

Questionable high-water marks such at RM 45.2 (Figure B-2) were not considered in the calibration and verification as it is 3.5 feet higher than the recorded peak stage but shown on the plot for disclosure of all data received.

Table B-1. Stream Gages with Observed Data Available for Calibration and Verification Dec-Jan. 2006 Flood January 1997 Flood
Gage Parameter Observed Computed Difference Observed Computed Difference Sacramento
River at I
Street
(DWR
A02100)
Peak Stage
(feet,
NAVD88)

30.07 30.01 -0.06 ft 32.92 32.90 -0.02 ft
Sacramento
River at
Freeport
(USGS
11447650)
Peak Stage
(feet,
NAVD88)

23.30 23.38 +0.08 ft 25.99 26.01 +0.02 ft
Peak Flow
(cfs) 97,200 94,950 -2.3% 115,000 108,645 -5.5%
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page B-2 Figure B-1. Stream Gage Location Map
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page B-3 Figure B-2. Calibration Analysis Maximum Water Surface Elevation Profile, ARS Sacramento River East Levee Reach
Figure B-3. Verification Analysis Maximum Water Surface Elevation Profile, ARS Sacramento River East Levee Reach
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Appendix C
Bridge Debris Loading Guidance
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-1 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-2 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-3 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-4 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-5 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-6 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-7 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-8 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-9 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL

APPENDIX D

ULDC Hydraulic Parameter Profile Tabulations

Acronyms
DWSE design water surface elevation
MTOL minimum top of levee
HTOL hydraulic top of levee
SVRP seismic vulnerability restoration profile
Table D-1 American River South Levee
Table D-2 Sacramento River East Levee
SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-1 Table D-1. ULDC Hydraulic Parameter Profiles, American River South Levee Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1000+00 33.40 36.40 36.40 33.42 1052+00 34.55 37.55 37.55 34.12 1001+00 33.44 36.44 36.44 33.45 1053+00 34.56 37.56 37.56 34.13 1002+00 33.47 36.47 36.47 33.49 1054+00 34.58 37.58 37.58 34.14 1003+00 33.51 36.51 36.51 33.52 1055+00 34.60 37.60 37.60 34.14 1004+00 33.54 36.54 36.54 33.55 1056+00 34.62 37.62 37.62 34.15 1005+00 33.54 36.54 36.54 33.55 1057+00 34.64 37.64 37.64 34.16 1006+00 33.54 36.54 36.54 33.55 1058+00 34.65 37.65 37.65 34.17 1007+00 33.54 36.54 36.54 33.55 1059+00 34.67 37.67 37.67 34.18 1008+00 33.54 36.54 36.54 33.55 1060+00 34.69 37.69 37.69 34.19 1009+00 33.54 36.54 36.54 33.56 1061+00 34.71 37.71 37.71 34.19 1010+00 33.56 36.56 36.56 33.57 1062+00 34.73 37.73 37.73 34.21 1011+00 33.61 36.61 36.61 33.60 1063+00 34.77 37.77 37.77 34.22 1012+00 33.67 36.67 36.67 33.63 1064+00 34.80 37.80 37.80 34.24 1013+00 33.72 36.72 36.72 33.66 1065+00 34.84 37.84 37.84 34.26 1014+00 33.73 36.73 36.73 33.66 1066+00 34.87 37.87 37.87 34.28 1015+00 33.73 36.73 36.73 33.66 1067+00 34.91 37.91 37.91 34.30 1016+00 33.76 36.76 36.76 33.68 1068+00 34.94 37.94 37.94 34.32 1017+00 33.80 36.80 36.80 33.70 1069+00 34.98 37.98 37.98 34.34 1018+00 33.84 36.84 36.84 33.73 1070+00 35.01 38.01 38.01 34.36 1019+00 33.87 36.87 36.87 33.75 1071+00 35.05 38.05 38.05 34.38 1020+00 33.91 36.91 36.91 33.76 1072+00 35.07 38.07 38.07 34.40 1021+00 33.94 36.94 36.94 33.78 1073+00 35.10 38.10 38.10 34.41 1022+00 33.97 36.97 36.97 33.80 1074+00 35.12 38.12 38.12 34.42 1023+00 34.00 37.00 37.00 33.81 1075+00 35.14 38.14 38.14 34.44 1024+00 34.01 37.01 37.01 33.82 1076+00 35.17 38.17 38.17 34.45 1025+00 34.01 37.01 37.01 33.83 1077+00 35.19 38.19 38.19 34.46 1026+00 34.01 37.01 37.01 33.83 1078+00 35.22 38.22 38.22 34.48 1027+00 34.02 37.02 37.02 33.84 1079+00 35.24 38.24 38.24 34.49 1028+00 34.05 37.05 37.05 33.85 1080+00 35.26 38.26 38.26 34.51 1029+00 34.08 37.08 37.08 33.87 1081+00 35.28 38.28 38.28 34.52 1030+00 34.10 37.10 37.10 33.88 1082+00 35.29 38.29 38.29 34.52 1031+00 34.13 37.13 37.13 33.89 1083+00 35.29 38.29 38.29 34.52 1032+00 34.16 37.16 37.16 33.91 1084+00 35.30 38.30 38.30 34.52 1033+00 34.18 37.18 37.18 33.92 1085+00 35.34 38.34 38.34 34.54 1034+00 34.21 37.21 37.21 33.93 1086+00 35.36 38.36 38.36 34.54 1035+00 34.23 37.23 37.23 33.94 1087+00 35.40 38.40 38.40 34.56 1036+00 34.25 37.25 37.25 33.95 1088+00 35.50 38.50 38.50 34.63 1037+00 34.27 37.27 37.27 33.97 1089+00 35.52 38.52 38.52 34.64 1038+00 34.29 37.29 37.29 33.98 1090+00 35.53 38.53 38.53 34.64 1039+00 34.31 37.31 37.31 33.99 1091+00 35.54 38.54 38.54 34.65 1040+00 34.34 37.34 37.34 34.00 1092+00 35.55 38.55 38.55 34.66 1041+00 34.36 37.36 37.36 34.01 1093+00 35.57 38.57 38.57 34.67 1042+00 34.38 37.38 37.38 34.03 1094+00 35.58 38.58 38.58 34.68 1043+00 34.40 37.40 37.40 34.04 1095+00 35.59 38.59 38.59 34.68 1044+00 34.43 37.43 37.43 34.05 1096+00 35.61 38.61 38.61 34.69 1045+00 34.45 37.45 37.45 34.06 1097+00 35.60 38.60 38.60 34.69 1046+00 34.47 37.47 37.47 34.07 1098+00 35.59 38.59 38.59 34.68 1047+00 34.48 37.48 37.48 34.08 1099+00 35.91 38.91 38.91 34.87 1048+00 34.49 37.49 37.49 34.09 1100+00 36.01 39.01 39.01 34.94 1049+00 34.51 37.51 37.51 34.10 1101+00 36.12 39.12 39.12 35.02 1050+00 34.52 37.52 37.52 34.10 1102+00 36.12 39.12 39.12 35.02 1051+00 34.53 37.53 37.53 34.11 1103+00 36.14 39.14 39.14 35.04

SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-2 Table D-1. ULDC Hydraulic Parameter Profiles, American River South Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1104+00 36.17 39.17 39.17 35.05 1156+00 37.07 40.07 40.07 35.56 1105+00 36.19 39.19 39.19 35.07 1157+00 37.07 40.07 40.07 35.57 1106+00 36.21 39.21 39.21 35.09 1158+00 37.07 40.07 40.07 35.58 1107+00 36.23 39.23 39.23 35.10 1159+00 37.07 40.07 40.07 35.58 1108+00 36.25 39.25 39.25 35.12 1160+00 37.07 40.07 40.07 35.59 1109+00 36.27 39.27 39.27 35.13 1161+00 37.07 40.07 40.07 35.60 1110+00 36.29 39.29 39.29 35.15 1162+00 37.07 40.07 40.07 35.61 1111+00 36.29 39.29 39.29 35.14 1163+00 37.09 40.09 40.09 35.62 1112+00 36.29 39.29 39.29 35.12 1164+00 37.10 40.10 40.10 35.63 1113+00 36.36 39.36 39.36 35.17 1165+00 37.11 40.11 40.11 35.64 1114+00 36.36 39.36 39.36 35.17 1166+00 37.13 40.13 40.13 35.65 1115+00 36.36 39.36 39.36 35.17 1167+00 37.14 40.14 40.14 35.66 1116+00 36.36 39.36 39.36 35.17 1168+00 37.15 40.15 40.15 35.67 1117+00 36.30 39.30 39.30 35.13 1169+00 37.17 40.17 40.17 35.68 1118+00 36.15 39.15 39.15 35.01 1170+00 37.18 40.18 40.18 35.69 1119+00 36.21 39.21 39.21 35.04 1171+00 37.19 40.19 40.19 35.70 1120+00 36.33 39.33 39.33 35.13 1172+00 37.21 40.21 40.21 35.71 1121+00 36.36 39.36 39.36 35.14 1173+00 37.23 40.23 40.23 35.73 1122+00 36.38 39.38 39.38 35.16 1174+00 37.24 40.24 40.24 35.74 1123+00 36.41 39.41 39.41 35.17 1175+00 37.26 40.26 40.26 35.76 1124+00 36.44 39.44 39.44 35.18 1176+00 37.28 40.28 40.28 35.77 1125+00 36.46 39.46 39.46 35.20 1177+00 37.30 40.30 40.30 35.78 1126+00 36.49 39.49 39.49 35.21 1178+00 37.31 40.31 40.31 35.80 1127+00 36.52 39.52 39.52 35.23 1179+00 37.33 40.33 40.33 35.81 1128+00 36.55 39.55 39.55 35.24 1180+00 37.35 40.35 40.35 35.82 1129+00 36.57 39.57 39.57 35.25 1181+00 37.36 40.36 40.36 35.84 1130+00 36.60 39.60 39.60 35.26 1182+00 37.37 40.37 40.37 35.84 1131+00 36.62 39.62 39.62 35.27 1183+00 37.37 40.37 40.37 35.85 1132+00 36.65 39.65 39.65 35.28 1184+00 37.38 40.38 40.38 35.85 1133+00 36.68 39.68 39.68 35.29 1185+00 37.38 40.38 40.38 35.86 1134+00 36.70 39.70 39.70 35.30 1186+00 37.39 40.39 40.39 35.86 1135+00 36.73 39.73 39.73 35.31 1187+00 37.41 40.41 40.41 35.88 1136+00 36.76 39.76 39.76 35.32 1188+00 37.47 40.47 40.47 35.92 1137+00 36.78 39.78 39.78 35.33 1189+00 37.52 40.52 40.52 35.96 1138+00 36.81 39.81 39.81 35.34 1190+00 37.58 40.58 40.58 36.00 1139+00 36.84 39.84 39.84 35.35 1191+00 37.64 40.64 40.64 36.04 1140+00 36.85 39.85 39.85 35.37 1192+00 37.69 40.69 40.69 36.08 1141+00 36.87 39.87 39.87 35.38 1193+00 37.75 40.75 40.75 36.12 1142+00 36.89 39.89 39.89 35.40 1194+00 37.77 40.77 40.77 36.15 1143+00 36.91 39.91 39.91 35.41 1195+00 37.75 40.75 40.75 36.14 1144+00 36.93 39.93 39.93 35.42 1196+00 37.90 40.90 40.90 36.26 1145+00 36.95 39.95 39.95 35.44 1197+00 37.92 40.92 40.92 36.26 1146+00 36.97 39.97 39.97 35.45 1198+00 37.93 40.93 40.93 36.27 1147+00 36.99 39.99 39.99 35.47 1199+00 37.95 40.95 40.95 36.27 1148+00 37.01 40.01 40.01 35.48 1200+00 37.97 40.97 40.97 36.28 1149+00 37.03 40.03 40.03 35.49 1201+00 37.98 40.98 40.98 36.28 1150+00 37.04 40.04 40.04 35.51 1202+00 38.00 41.00 41.00 36.29 1151+00 37.06 40.06 40.06 35.52 1203+00 38.01 41.01 41.01 36.29 1152+00 37.07 40.07 40.07 35.53 1204+00 38.08 41.08 41.08 36.35 1153+00 37.07 40.07 40.07 35.54 1205+00 38.12 41.12 41.12 36.34 1154+00 37.07 40.07 40.07 35.55 1206+00 38.15 41.15 41.15 36.36 1155+00 37.07 40.07 40.07 35.55 1207+00 38.18 41.18 41.18 36.39

SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-3 Table D-1. ULDC Hydraulic Parameter Profiles, American River South Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1208+00 38.22 41.22 41.22 36.42 1260+00 39.88 42.88 42.88 37.80 1209+00 38.25 41.25 41.25 36.44 1261+00 39.92 42.92 42.92 37.85 1210+00 38.27 41.27 41.27 36.46 1262+00 39.96 42.96 42.96 37.89 1211+00 38.30 41.30 41.30 36.48 1263+00 40.01 43.01 43.01 37.94 1212+00 38.33 41.33 41.33 36.49 1264+00 40.05 43.05 43.05 37.99 1213+00 38.36 41.36 41.36 36.51 1265+00 40.09 43.09 43.09 38.03 1214+00 38.38 41.38 41.38 36.53 1266+00 40.13 43.13 43.13 38.08 1215+00 38.41 41.41 41.41 36.55 1267+00 40.17 43.17 43.17 38.11 1216+00 38.44 41.44 41.44 36.56 1268+00 40.21 43.21 43.21 38.13 1217+00 38.46 41.46 41.46 36.58 1269+00 40.25 43.25 43.25 38.16 1218+00 38.46 41.46 41.46 36.58 1270+00 40.29 43.29 43.29 38.18 1219+00 38.46 41.46 41.46 36.57 1271+00 40.35 43.35 43.35 38.22 1220+00 38.47 41.47 41.47 36.57 1272+00 40.45 43.45 43.45 38.31 1221+00 38.47 41.47 41.47 36.57 1273+00 40.55 43.55 43.55 38.40 1222+00 38.47 41.47 41.47 36.56 1274+00 40.64 43.64 43.64 38.49 1223+00 38.47 41.47 41.47 36.56 1275+00 40.74 43.74 43.74 38.57 1224+00 38.47 41.47 41.47 36.56 1276+00 40.81 43.81 43.81 38.63 1225+00 38.48 41.48 41.48 36.55 1277+00 40.87 43.87 43.87 38.69 1226+00 38.48 41.48 41.48 36.55 1278+00 40.93 43.93 43.93 38.75 1227+00 38.48 41.48 41.48 36.55 1279+00 41.00 44.00 44.00 38.81 1228+00 38.50 41.50 41.50 36.57 1280+00 41.05 44.05 44.05 38.86 1229+00 38.57 41.57 41.57 36.62 1281+00 41.09 44.09 44.09 38.90 1230+00 38.63 41.63 41.63 36.68 1282+00 41.13 44.13 44.13 38.94 1231+00 38.69 41.69 41.69 36.74 1283+00 41.17 44.17 44.17 38.98 1232+00 38.76 41.76 41.76 36.80 1284+00 41.21 44.21 44.21 39.02 1233+00 38.82 41.82 41.82 36.86 1285+00 41.26 44.26 44.26 39.07 1234+00 38.88 41.88 41.88 36.91 1286+00 41.23 44.23 44.23 39.05 1235+00 38.94 41.94 41.94 36.97 1287+00 41.17 44.17 44.17 39.02 1236+00 39.01 42.01 42.01 37.03 1288+00 41.12 44.12 44.12 38.98 1237+00 39.07 42.07 42.07 37.09 1289+00 41.07 44.07 44.07 38.95 1238+00 39.14 42.14 42.14 37.13 1290+00 41.01 44.01 44.01 38.91 1239+00 39.23 42.23 42.23 37.15 1291+00 40.96 43.96 43.96 38.88 1240+00 39.31 42.31 42.31 37.18 1292+00 41.05 44.05 44.05 38.97 1241+00 39.40 42.40 42.40 37.20 1293+00 41.26 44.26 44.26 39.16 1242+00 39.48 42.48 42.48 37.22 1294+00 41.47 44.47 44.47 39.35 1243+00 39.56 42.56 42.56 37.24 1295+00 41.60 44.60 44.60 39.47 1244+00 39.65 42.65 42.65 37.26 1296+00 41.69 44.69 44.69 39.52 1245+00 39.69 42.69 42.69 37.28 1297+00 41.78 44.78 44.78 39.58 1246+00 39.69 42.69 42.69 37.31 1298+00 41.86 44.86 44.86 39.64 1247+00 39.69 42.69 42.69 37.34 1299+00 41.95 44.95 44.95 39.70 1248+00 39.69 42.69 42.69 37.37 1300+00 42.04 45.04 45.04 39.78 1249+00 39.69 42.69 42.69 37.40 1301+00 42.14 45.14 45.14 39.86 1250+00 39.69 42.69 42.69 37.43 1302+00 42.23 45.23 45.23 39.94 1251+00 39.69 42.69 42.69 37.46 1303+00 42.33 45.33 45.33 40.02 1252+00 39.68 42.68 42.68 37.48 1304+00 42.42 45.42 45.42 40.10 1253+00 39.68 42.68 42.68 37.51 1305+00 42.48 45.48 45.48 40.14 1254+00 39.68 42.68 42.68 37.54 1306+00 42.49 45.49 45.49 40.16 1255+00 39.68 42.68 42.68 37.57 1307+00 42.50 45.50 45.50 40.18 1256+00 39.71 42.71 42.71 37.61 1308+00 42.51 45.51 45.51 40.20 1257+00 39.75 42.75 42.75 37.66 1309+00 42.53 45.53 45.53 40.22 1258+00 39.80 42.80 42.80 37.71 1310+00 42.54 45.54 45.54 40.24 1259+00 39.84 42.84 42.84 37.75 1311+00 42.57 45.57 45.57 40.29 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-4 Table D-1. ULDC Hydraulic Parameter Profiles, American River South Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1312+00 42.60 45.60 45.60 40.34 1364+00 45.40 48.40 48.40 42.45 1313+00 42.63 45.63 45.63 40.39 1365+00 45.61 48.61 48.61 42.62 1314+00 42.65 45.65 45.65 40.44 1366+00 45.66 48.66 48.66 42.66 1315+00 42.70 45.70 45.70 40.49 1367+00 45.71 48.71 48.71 42.70 1316+00 42.76 45.76 45.76 40.55 1368+00 45.75 48.75 48.75 42.74 1317+00 42.82 45.82 45.82 40.61 1369+00 45.80 48.80 48.80 42.77 1318+00 42.87 45.87 45.87 40.67 1370+00 45.82 48.82 48.82 42.79 1319+00 42.93 45.93 45.93 40.73 1371+00 45.84 48.84 48.84 42.80 1320+00 42.77 45.77 45.77 40.66 1372+00 45.85 48.85 48.85 42.81 1321+00 42.91 45.91 45.91 40.74 1373+00 45.87 48.87 48.87 42.82 1322+00 43.05 46.05 46.05 40.83 1374+00 45.88 48.88 48.88 42.83 1323+00 43.19 46.19 46.19 40.91 1375+00 45.89 48.89 48.89 42.84 1324+00 43.32 46.32 46.32 41.00 1376+00 45.91 48.91 48.91 42.85 1325+00 43.46 46.46 46.46 41.09 1377+00 45.92 48.92 48.92 42.86 1326+00 43.50 46.50 46.50 41.12 1378+00 45.94 48.94 48.94 42.87 1327+00 43.55 46.55 46.55 41.16 1379+00 45.95 48.95 48.95 42.88 1328+00 43.59 46.59 46.59 41.19 1380+00 45.96 48.96 48.96 42.89 1329+00 43.64 46.64 46.64 41.23 1381+00 45.98 48.98 48.98 42.90 1330+00 43.68 46.68 46.68 41.26 1382+00 46.03 49.03 49.03 42.95 1331+00 43.67 46.67 46.67 41.25 1383+00 46.10 49.10 49.10 43.00 1332+00 43.65 46.65 46.65 41.24 1384+00 46.16 49.16 49.16 43.05 1333+00 43.64 46.64 46.64 41.23 1385+00 46.23 49.23 49.23 43.10 1334+00 43.62 46.62 46.62 41.22 1386+00 46.30 49.30 49.30 43.16 1335+00 43.60 46.60 46.60 41.20 1387+00 46.37 49.37 49.37 43.21 1336+00 43.67 46.67 46.67 41.21 1388+00 46.32 49.32 49.32 43.16 1337+00 43.74 46.74 46.74 41.23 1389+00 46.33 49.33 49.33 43.18 1338+00 43.82 46.82 46.82 41.24 1390+00 46.37 49.37 49.37 43.22 1339+00 43.90 46.90 46.90 41.26 1391+00 46.42 49.42 49.42 43.27 1340+00 43.98 46.98 46.98 41.27 1392+00 46.46 49.46 49.46 43.32 1341+00 44.06 47.06 47.06 41.29 1393+00 46.50 49.50 49.50 43.36 1342+00 44.11 47.11 47.11 41.32 1394+00 46.57 49.57 49.57 43.42 1343+00 44.17 47.17 47.17 41.35 1395+00 46.66 49.66 49.66 43.48 1344+00 44.23 47.23 47.23 41.38 1396+00 46.74 49.74 49.74 43.54 1345+00 44.28 47.28 47.28 41.41 1397+00 46.82 49.82 49.82 43.60 1346+00 44.34 47.34 47.34 41.45 1398+00 46.91 49.91 49.91 43.66 1347+00 44.62 47.62 47.62 41.67 1399+00 46.95 49.95 49.95 43.70 1348+00 44.67 47.67 47.67 41.71 1400+00 46.98 49.98 49.98 43.73 1349+00 44.73 47.73 47.73 41.75 1401+00 47.01 50.01 50.01 43.76 1350+00 44.78 47.78 47.78 41.79 1402+00 47.04 50.04 50.04 43.79 1351+00 44.84 47.84 47.84 41.83 1403+00 47.07 50.07 50.07 43.82 1352+00 44.89 47.89 47.89 41.87 1404+00 47.11 50.11 50.11 43.85 1353+00 44.95 47.95 47.95 41.91 1405+00 47.14 50.14 50.14 43.88 1354+00 45.01 48.01 48.01 41.95 1406+00 47.18 50.18 50.18 43.91 1355+00 45.06 48.06 48.06 41.99 1407+00 47.22 50.22 50.22 43.94 1356+00 45.12 48.12 48.12 42.03 1408+00 47.26 50.26 50.26 43.97 1357+00 45.16 48.16 48.16 42.08 1409+00 47.30 50.30 50.30 44.00 1358+00 45.19 48.19 48.19 42.15 1410+00 47.33 50.33 50.33 44.02 1359+00 45.22 48.22 48.22 42.22 1411+00 47.33 50.33 50.33 44.03 1360+00 45.24 48.24 48.24 42.29 1412+00 47.34 50.34 50.34 44.03 1361+00 45.26 48.26 48.26 42.36 1413+00 47.34 50.34 50.34 44.04 1362+00 45.16 48.16 48.16 42.27 1414+00 47.35 50.35 50.35 44.04 1363+00 45.26 48.26 48.26 42.34 1415+00 47.36 50.36 50.36 44.05 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-5 Table D-1. ULDC Hydraulic Parameter Profiles, American River South Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1416+00 47.35 50.35 50.35 44.05 1468+00 48.45 51.45 51.45 45.07 1417+00 47.34 50.34 50.34 44.04 1469+00 48.57 51.57 51.57 45.16 1418+00 47.34 50.34 50.34 44.04 1470+00 48.62 51.62 51.62 45.18 1419+00 47.33 50.33 50.33 44.03 1471+00 48.71 51.71 51.71 45.26 1420+00 47.32 50.32 50.32 44.03 1472+00 48.79 51.79 51.79 45.34 1421+00 47.31 50.31 50.31 44.02 1473+00 48.88 51.88 51.88 45.41 1422+00 47.31 50.31 50.31 44.03 1474+00 48.96 51.96 51.96 45.49 1423+00 47.33 50.33 50.33 44.04 1475+00 49.04 52.04 52.04 45.56 1424+00 47.35 50.35 50.35 44.06 1476+00 49.13 52.13 52.13 45.64 1425+00 47.36 50.36 50.36 44.07 1477+00 49.21 52.21 52.21 45.72 1426+00 47.37 50.37 50.37 44.08 1478+00 49.29 52.29 52.29 45.79 1427+00 47.37 50.37 50.37 44.08 1479+00 49.34 52.34 52.34 45.84 1428+00 47.37 50.37 50.37 44.08 1480+00 49.39 52.39 52.39 45.90 1429+00 47.37 50.37 50.37 44.09 1481+00 49.44 52.44 52.44 45.95 1430+00 47.38 50.38 50.38 44.09 1482+00 49.49 52.49 52.49 46.00 1431+00 47.41 50.41 50.41 44.12 1483+00 49.54 52.54 52.54 46.06 1432+00 47.45 50.45 50.45 44.15 1484+00 49.59 52.59 52.59 46.11 1433+00 47.48 50.48 50.48 44.18 1485+00 49.63 52.63 52.63 46.16 1434+00 47.51 50.51 50.51 44.21 1486+00 49.68 52.68 52.68 46.22 1435+00 47.52 50.52 50.52 44.22 1487+00 49.73 52.73 52.73 46.27 1436+00 47.50 50.50 50.50 44.20 1488+00 49.83 52.83 52.83 46.35 1437+00 47.47 50.47 50.47 44.18 1489+00 49.93 52.93 52.93 46.43 1438+00 47.44 50.44 50.44 44.16 1490+00 50.03 53.03 53.03 46.52 1439+00 47.42 50.42 50.42 44.15 1491+00 50.13 53.13 53.13 46.60 1440+00 47.46 50.46 50.46 44.19 1492+00 50.23 53.23 53.23 46.68 1441+00 47.53 50.53 50.53 44.24 1493+00 50.26 53.26 53.26 46.71 1442+00 47.59 50.59 50.59 44.30 1494+00 50.30 53.30 53.30 46.74 1443+00 47.66 50.66 50.66 44.35 1495+00 50.34 53.34 53.34 46.76 1444+00 47.72 50.72 50.72 44.41 1496+00 50.37 53.37 53.37 46.79 1445+00 47.78 50.78 50.78 44.46 1497+00 50.40 53.40 53.40 46.82 1446+00 47.84 50.84 50.84 44.51 1498+00 50.42 53.42 53.42 46.86 1447+00 47.90 50.90 50.90 44.56 1499+00 50.43 53.43 53.43 46.90 1448+00 47.96 50.96 50.96 44.61 1500+00 50.45 53.45 53.45 46.94 1449+00 48.02 51.02 51.02 44.66 1501+00 50.46 53.46 53.46 46.98 1450+00 48.10 51.10 51.10 44.72 1502+00 50.52 53.52 53.52 47.04 1451+00 48.18 51.18 51.18 44.78 1503+00 50.58 53.58 53.58 47.10 1452+00 48.25 51.25 51.25 44.84 1504+00 50.65 53.65 53.65 47.16 1453+00 48.33 51.33 51.33 44.90 1505+00 50.71 53.71 53.71 47.23 1454+00 48.40 51.40 51.40 44.96 1506+00 50.77 53.77 53.77 47.28 1455+00 48.48 51.48 51.48 45.01 1507+00 50.82 53.82 53.82 47.33 1456+00 48.55 51.55 51.55 45.07 1508+00 50.88 53.88 53.88 47.39 1457+00 48.63 51.63 51.63 45.13 1509+00 50.93 53.93 53.93 47.44 1458+00 48.70 51.70 51.70 45.19 1510+00 50.98 53.98 53.98 47.49 1459+00 48.69 51.69 51.69 45.19 1511+00 51.04 54.04 54.04 47.54 1460+00 48.66 51.66 51.66 45.17 1512+00 51.08 54.08 54.08 47.57 1461+00 48.63 51.63 51.63 45.15 1513+00 51.13 54.13 54.13 47.61 1462+00 48.60 51.60 51.60 45.14 1514+00 51.18 54.18 54.18 47.65 1463+00 48.57 51.57 51.57 45.12 1515+00 51.23 54.23 54.23 47.68 1464+00 48.54 51.54 51.54 45.10 1516+00 51.28 54.28 54.28 47.72 1465+00 48.50 51.50 51.50 45.08 1517+00 51.36 54.36 54.36 47.77 1466+00 48.47 51.47 51.47 45.07 1518+00 51.43 54.43 54.43 47.82 1467+00 48.44 51.44 51.44 45.05 1519+00 51.50 54.50 54.50 47.87 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-6 Table D-1. ULDC Hydraulic Parameter Profiles, American River South Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1520+00 51.57 54.57 54.57 47.92 1607+00 53.05 56.05 56.05 49.18 1521+00 51.70 54.70 54.70 48.02 1608+00 53.04 56.04 56.04 49.18 1522+00 51.84 54.84 54.84 48.12 1609+00 53.03 56.03 56.03 49.17 1523+00 51.97 54.97 54.97 48.22 1610+00 53.02 56.02 56.02 49.17 1524+00 52.10 55.10 55.10 48.32 1611+00 53.02 56.02 56.02 49.16 1525+00 52.14 55.14 55.14 48.35 1612+00 53.01 56.01 56.01 49.16 1526+00 52.15 55.15 55.15 48.35 1613+00 53.00 56.00 56.00 49.16 1527+00 52.15 55.15 55.15 48.35 1614+00 52.99 55.99 55.99 49.16 1528+00 52.18 55.18 55.18 48.38 1615+00 52.99 55.99 55.99 49.16 1529+00 52.23 55.23 55.23 48.42 1616+00 52.99 55.99 55.99 49.16 1530+00 52.27 55.27 55.27 48.45 1617+00 52.99 55.99 55.99 49.16 1531+00 52.31 55.31 55.31 48.49 1618+00 52.98 55.98 55.98 49.16 1532+00 52.35 55.35 55.35 48.53 1619+00 52.98 55.98 55.98 49.16 1533+00 52.39 55.39 55.39 48.56 1620+00 52.98 55.98 55.98 49.16 1534+00 52.44 55.44 55.44 48.60 1621+00 52.98 55.98 55.98 49.16 1535+00 52.48 55.48 55.48 48.63 1622+00 52.98 55.98 55.98 49.17 1536+00 52.52 55.52 55.52 48.67 1623+00 52.98 55.98 55.98 49.17 1537+00 52.56 55.56 55.56 48.71 1624+00 52.99 55.99 55.99 49.18 1538+00 52.58 55.58 55.58 48.73 1625+00 53.00 56.00 56.00 49.19 1539+00 52.60 55.60 55.60 48.75 1626+00 53.02 56.02 56.02 49.21 1540+00 52.62 55.62 55.62 48.76 1627+00 53.03 56.03 56.03 49.22 1541+00 52.64 55.64 55.64 48.78 1628+00 53.04 56.04 56.04 49.23 1542+00 52.66 55.66 55.66 48.80 1629+00 53.06 56.06 56.06 49.24 1543+00 52.68 55.68 55.68 48.81 1630+00 53.07 56.07 56.07 49.26 1544+00 52.69 55.69 55.69 48.83 1631+00 53.08 56.08 56.08 49.27 1545+00 52.71 55.71 55.71 48.85 1632+00 53.10 56.10 56.10 49.28 1546+00 52.73 55.73 55.73 48.86 1633+00 53.12 56.12 56.12 49.29 1547+00 52.74 55.74 55.74 48.88 1634+00 53.14 56.14 56.14 49.30 1548+00 52.76 55.76 55.76 48.90 1635+00 53.17 56.17 56.17 49.30 1549+00 52.78 55.78 55.78 48.91 1635+50 53.18 56.18 56.18 49.31 1550+00 52.80 55.80 55.80 48.93
1551+00 52.81 55.81 55.81 48.94
1552+00 52.81 55.81 55.81 48.94
1553+00 52.82 55.82 55.82 48.95
1554+00 52.82 55.82 55.82 48.95
1555+00 52.83 55.83 55.83 48.96
Mayhew Drain closure structure
1592+00 53.00 56.00 56.00 49.13
1593+00 53.01 56.01 56.01 49.13
1594+00 53.01 56.01 56.01 49.14
1595+00 53.02 56.02 56.02 49.14
1596+00 53.02 56.02 56.02 49.15
1597+00 53.03 56.03 56.03 49.15
1598+00 53.03 56.03 56.03 49.15
1599+00 53.04 56.04 56.04 49.16
1600+00 53.04 56.04 56.04 49.16
1601+00 53.05 56.05 56.05 49.17
1602+00 53.05 56.05 56.05 49.17
1603+00 53.06 56.06 56.06 49.18
1604+00 53.06 56.06 56.06 49.18
1605+00 53.07 56.07 56.07 49.19
1606+00 53.06 56.06 56.06 49.18

SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-7 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1000+00 33.40 36.40 36.40 33.42 1052+00 32.50 35.50 35.50 32.69 1001+00 33.39 36.39 36.39 33.41 1053+00 32.50 35.50 35.50 32.69 1002+00 33.38 36.38 36.38 33.40 1054+00 32.49 35.49 35.49 32.69 1003+00 33.37 36.37 36.37 33.39 1055+00 32.49 35.49 35.49 32.68 1004+00 33.37 36.37 36.37 33.38 1056+00 32.48 35.48 35.48 32.67 1005+00 33.36 36.36 36.36 33.37 1057+00 32.47 35.47 35.47 32.66 1006+00 33.35 36.35 36.35 33.36 1058+00 32.46 35.46 35.46 32.65 1007+00 33.34 36.34 36.34 33.35 1059+00 32.45 35.45 35.45 32.64 1008+00 33.33 36.33 36.33 33.34 1060+00 32.44 35.44 35.44 32.63 1009+00 33.32 36.32 36.32 33.33 1061+00 32.38 35.38 35.38 32.58 1010+00 33.31 36.31 36.31 33.32 1062+00 32.43 35.43 35.43 32.62 1011+00 33.30 36.30 36.30 33.31 1063+00 32.42 35.42 35.42 32.61 1012+00 33.28 36.28 36.28 33.29 1064+00 32.41 35.41 35.41 32.61 1013+00 33.26 36.26 36.26 33.27 1065+00 32.40 35.40 35.40 32.60 1014+00 33.25 36.25 36.25 33.26 1066+00 32.40 35.40 35.40 32.59 1015+00 33.23 36.23 36.23 33.24 1067+00 32.39 35.39 35.39 32.58 1016+00 33.21 36.21 36.21 33.22 1068+00 32.38 35.38 35.38 32.57 1017+00 33.19 36.19 36.19 33.20 1069+00 32.37 35.37 35.37 32.57 1018+00 33.18 36.18 36.18 33.19 1070+00 32.36 35.36 35.36 32.55 1019+00 33.17 36.17 36.17 33.18 1071+00 32.35 35.35 35.35 32.54 1020+00 33.17 36.17 36.17 33.18 1072+00 32.34 35.34 35.34 32.53 1021+00 33.16 36.16 36.16 33.17 1073+00 32.33 35.33 35.33 32.52 1022+00 33.15 36.15 36.15 33.16 1074+00 32.31 35.31 35.31 32.51 1023+00 33.14 36.14 36.14 33.15 1075+00 32.30 35.30 35.30 32.50 1024+00 33.12 36.12 36.12 33.13 1076+00 32.29 35.29 35.29 32.49 1025+00 33.11 36.11 36.11 33.12 1077+00 32.28 35.28 35.28 32.47 1026+00 33.09 36.09 36.09 33.11 1078+00 32.27 35.27 35.27 32.46 1027+00 33.08 36.08 36.08 33.09 1079+00 32.26 35.26 35.26 32.45 1028+00 33.07 36.07 36.07 33.08 1080+00 32.25 35.25 35.24 32.44 1029+00 33.05 36.05 36.05 33.07 1081+00 32.24 35.24 35.24 32.43 1030+00 33.04 36.04 36.04 33.05 1082+00 32.23 35.23 35.23 32.42 1031+00 33.02 36.02 36.02 33.03 1083+00 32.22 35.22 35.22 32.41 1032+00 33.00 36.00 36.00 33.02 1084+00 32.21 35.21 35.21 32.40 1033+00 32.99 35.99 35.99 33.00 1085+00 32.20 35.20 35.20 32.39 1034+00 32.97 35.97 35.97 32.98 1086+00 32.19 35.19 35.19 32.38 1035+00 32.95 35.95 35.95 32.97 1087+00 32.18 35.18 35.18 32.37 1036+00 32.94 35.94 35.94 32.95 1088+00 32.17 35.17 35.17 32.36 1037+00 32.92 35.92 35.92 32.93 1089+00 32.16 35.16 35.16 32.35 1038+00 32.86 35.86 35.86 32.91 1090+00 32.16 35.16 35.15 32.34 1039+00 32.63 35.63 35.63 32.81 1091+00 32.15 35.15 35.14 32.33 1040+00 32.65 35.65 35.65 32.83 1092+00 32.14 35.14 35.13 32.32 1041+00 32.63 35.63 35.63 32.82 1093+00 32.13 35.13 35.12 32.32 1042+00 32.62 35.62 35.62 32.80 1094+00 32.12 35.12 35.11 32.31 1043+00 32.60 35.60 35.60 32.79 1095+00 32.11 35.11 35.10 32.30 1044+00 32.58 35.58 35.58 32.77 1096+00 32.10 35.10 35.09 32.29 1045+00 32.57 35.57 35.57 32.76 1097+00 32.08 35.08 35.07 32.27 1046+00 32.55 35.55 35.55 32.74 1098+00 32.07 35.07 35.06 32.26 1047+00 32.54 35.54 35.54 32.73 1099+00 32.05 35.05 35.04 32.24 1048+00 32.52 35.52 35.52 32.71 1100+00 32.04 35.04 35.02 32.23 1049+00 32.51 35.51 35.51 32.70 1101+00 32.02 35.02 35.00 32.21 1050+00 32.51 35.51 35.51 32.70 1102+00 32.01 35.01 34.99 32.20 1051+00 32.50 35.50 35.50 32.69 1103+00 32.01 35.01 34.99 32.20 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-8 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1104+00 32.02 35.02 35.00 32.21 1156+00 31.50 34.50 34.46 31.70 1105+00 32.02 35.02 35.00 32.20 1157+00 31.50 34.50 34.45 31.69 1106+00 32.01 35.01 35.00 32.20 1158+00 31.49 34.49 34.44 31.68 1107+00 32.01 35.01 35.00 32.20 1159+00 31.48 34.48 34.44 31.67 1108+00 32.01 35.01 35.00 32.19 1160+00 31.48 34.48 34.43 31.67 1109+00 32.00 35.00 34.99 32.19 1161+00 31.47 34.47 34.42 31.66 1110+00 31.99 34.99 34.97 32.17 1162+00 31.46 34.46 34.41 31.65 1111+00 31.97 34.97 34.96 32.16 1163+00 31.45 34.45 34.40 31.64 1112+00 31.96 34.96 34.94 32.14 1164+00 31.44 34.44 34.39 31.64 1113+00 31.94 34.94 34.93 32.13 1165+00 31.44 34.44 34.39 31.63 1114+00 31.93 34.93 34.91 32.11 1166+00 31.43 34.43 34.38 31.62 1115+00 31.91 34.91 34.90 32.10 1167+00 31.42 34.42 34.37 31.61 1116+00 31.90 34.90 34.88 32.09 1168+00 31.41 34.41 34.35 31.60 1117+00 31.89 34.89 34.87 32.07 1169+00 31.40 34.40 34.34 31.59 1118+00 31.87 34.87 34.85 32.06 1170+00 31.39 34.39 34.33 31.58 1119+00 31.86 34.86 34.83 32.04 1171+00 31.38 34.38 34.32 31.57 1120+00 31.84 34.84 34.82 32.03 1172+00 31.37 34.37 34.31 31.56 1121+00 31.83 34.83 34.80 32.01 1173+00 31.36 34.36 34.30 31.55 1122+00 31.81 34.81 34.78 32.00 1174+00 31.35 34.35 34.29 31.54 1123+00 31.80 34.80 34.77 31.98 1175+00 31.34 34.34 34.28 31.53 1124+00 31.78 34.78 34.75 31.97 1176+00 31.33 34.33 34.27 31.52 1125+00 31.76 34.76 34.73 31.95 1177+00 31.32 34.32 34.26 31.51 1126+00 31.75 34.75 34.72 31.94 1178+00 31.31 34.31 34.25 31.50 1127+00 31.73 34.73 34.70 31.92 1179+00 31.30 34.30 34.24 31.49 1128+00 31.73 34.73 34.70 31.92 1180+00 31.29 34.29 34.23 31.48 1129+00 31.72 34.72 34.69 31.91 1181+00 31.28 34.28 34.22 31.47 1130+00 31.71 34.71 34.67 31.90 1182+00 31.28 34.28 34.21 31.47 1131+00 31.70 34.70 34.66 31.89 1183+00 31.27 34.27 34.20 31.46 1132+00 31.69 34.69 34.65 31.88 1184+00 31.26 34.26 34.20 31.45 1133+00 31.68 34.68 34.64 31.87 1185+00 31.25 34.25 34.19 31.44 1134+00 31.67 34.67 34.63 31.86 1186+00 31.24 34.24 34.18 31.43 1135+00 31.66 34.66 34.62 31.85 1187+00 31.23 34.23 34.17 31.42 1136+00 31.65 34.65 34.61 31.84 1188+00 31.23 34.23 34.16 31.42 1137+00 31.64 34.64 34.60 31.83 1189+00 31.22 34.22 34.15 31.41 1138+00 31.63 34.63 34.59 31.82 1190+00 31.21 34.21 34.14 31.40 1139+00 31.63 34.63 34.58 31.81 1191+00 31.20 34.20 34.13 31.39 1140+00 31.62 34.62 34.58 31.81 1192+00 31.19 34.19 34.12 31.38 1141+00 31.62 34.62 34.57 31.80 1193+00 31.18 34.18 34.11 31.37 1142+00 31.61 34.61 34.57 31.80 1194+00 31.17 34.17 34.10 31.36 1143+00 31.60 34.60 34.56 31.79 1195+00 31.16 34.16 34.09 31.35 1144+00 31.60 34.60 34.56 31.79 1196+00 31.16 34.16 34.08 31.34 1145+00 31.59 34.59 34.55 31.78 1197+00 31.15 34.15 34.08 31.34 1146+00 31.58 34.58 34.54 31.77 1198+00 31.14 34.14 34.07 31.33 1147+00 31.57 34.57 34.53 31.76 1199+00 31.13 34.13 34.06 31.32 1148+00 31.56 34.56 34.52 31.75 1200+00 31.12 34.12 34.05 31.31 1149+00 31.55 34.55 34.51 31.74 1201+00 31.11 34.11 34.04 31.30 1150+00 31.55 34.55 34.50 31.73 1202+00 31.11 34.11 34.03 31.29 1151+00 31.54 34.54 34.50 31.73 1203+00 31.10 34.10 34.02 31.29 1152+00 31.53 34.53 34.49 31.72 1204+00 31.09 34.09 34.01 31.28 1153+00 31.53 34.53 34.48 31.72 1205+00 31.08 34.08 34.00 31.27 1154+00 31.52 34.52 34.47 31.71 1206+00 31.07 34.07 34.00 31.26 1155+00 31.51 34.51 34.47 31.70 1207+00 31.06 34.06 33.99 31.25 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-9 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1208+00 31.05 34.05 33.98 31.24 1260+00 30.57 33.57 33.46 30.76 1209+00 31.05 34.05 33.97 31.23 1261+00 30.56 33.56 33.45 30.75 1210+00 31.04 34.04 33.96 31.23 1262+00 30.55 33.55 33.44 30.74 1211+00 31.03 34.03 33.95 31.22 1263+00 30.54 33.54 33.43 30.73 1212+00 31.02 34.02 33.95 31.21 1264+00 30.53 33.53 33.42 30.72 1213+00 31.01 34.01 33.94 31.20 1265+00 30.52 33.52 33.41 30.72 1214+00 31.00 34.00 33.93 31.19 1266+00 30.52 33.52 33.41 30.71 1215+00 30.99 33.99 33.92 31.18 1267+00 30.51 33.51 33.40 30.70 1216+00 30.98 33.98 33.90 31.17 1268+00 30.50 33.50 33.39 30.69 1217+00 30.97 33.97 33.89 31.16 1269+00 30.49 33.49 33.38 30.69 1218+00 30.96 33.96 33.88 31.15 1270+00 30.49 33.49 33.37 30.68 1219+00 30.95 33.95 33.87 31.14 1271+00 30.48 33.48 33.36 30.67 1220+00 30.94 33.94 33.86 31.13 1272+00 30.47 33.47 33.36 30.66 1221+00 30.93 33.93 33.85 31.11 1273+00 30.46 33.46 33.35 30.66 1222+00 30.92 33.92 33.84 31.10 1274+00 30.46 33.46 33.34 30.65 1223+00 30.90 33.90 33.82 31.09 1275+00 30.45 33.45 33.33 30.64 1224+00 30.89 33.89 33.81 31.08 1276+00 30.44 33.44 33.32 30.63 1225+00 30.88 33.88 33.80 31.07 1277+00 30.43 33.43 33.32 30.63 1226+00 30.87 33.87 33.79 31.06 1278+00 30.43 33.43 33.31 30.62 1227+00 30.86 33.86 33.78 31.05 1279+00 30.42 33.42 33.30 30.61 1228+00 30.85 33.85 33.77 31.04 1280+00 30.41 33.41 33.29 30.61 1229+00 30.84 33.84 33.75 31.03 1281+00 30.41 33.41 33.29 30.60 1230+00 30.83 33.83 33.74 31.02 1282+00 30.40 33.40 33.28 30.60 1231+00 30.82 33.82 33.73 31.01 1283+00 30.40 33.40 33.27 30.59 1232+00 30.81 33.81 33.72 31.00 1284+00 30.39 33.39 33.27 30.59 1233+00 30.80 33.80 33.71 30.99 1285+00 30.39 33.39 33.26 30.58 1234+00 30.79 33.79 33.70 30.98 1286+00 30.38 33.38 33.26 30.58 1235+00 30.78 33.78 33.69 30.97 1287+00 30.38 33.38 33.25 30.57 1236+00 30.77 33.77 33.68 30.96 1288+00 30.37 33.37 33.24 30.57 1237+00 30.76 33.76 33.67 30.96 1289+00 30.36 33.36 33.24 30.56 1238+00 30.75 33.75 33.66 30.95 1290+00 30.36 33.36 33.23 30.55 1239+00 30.75 33.75 33.65 30.94 1291+00 30.35 33.35 33.22 30.55 1240+00 30.74 33.74 33.64 30.93 1292+00 30.34 33.34 33.21 30.54 1241+00 30.73 33.73 33.63 30.92 1293+00 30.34 33.34 33.21 30.53 1242+00 30.72 33.72 33.62 30.91 1294+00 30.33 33.33 33.20 30.53 1243+00 30.71 33.71 33.61 30.90 1295+00 30.32 33.32 33.19 30.52 1244+00 30.70 33.70 33.61 30.90 1296+00 30.32 33.32 33.19 30.51 1245+00 30.70 33.70 33.60 30.89 1297+00 30.31 33.31 33.18 30.51 1246+00 30.69 33.69 33.59 30.88 1298+00 30.30 33.30 33.17 30.50 1247+00 30.68 33.68 33.58 30.87 1299+00 30.30 33.30 33.16 30.49 1248+00 30.67 33.67 33.57 30.86 1300+00 30.29 33.29 33.15 30.48 1249+00 30.67 33.67 33.56 30.86 1301+00 30.28 33.28 33.14 30.48 1250+00 30.66 33.66 33.56 30.85 1302+00 30.27 33.27 33.13 30.47 1251+00 30.65 33.65 33.55 30.84 1303+00 30.26 33.26 33.12 30.46 1252+00 30.64 33.64 33.54 30.83 1304+00 30.25 33.25 33.11 30.45 1253+00 30.63 33.63 33.53 30.82 1305+00 30.24 33.24 33.10 30.44 1254+00 30.62 33.62 33.52 30.81 1306+00 30.24 33.24 33.09 30.43 1255+00 30.61 33.61 33.51 30.80 1307+00 30.23 33.23 33.08 30.42 1256+00 30.60 33.60 33.50 30.80 1308+00 30.22 33.22 33.07 30.42 1257+00 30.59 33.59 33.49 30.79 1309+00 30.21 33.21 33.06 30.41 1258+00 30.59 33.59 33.48 30.78 1310+00 30.20 33.20 33.05 30.40 1259+00 30.58 33.58 33.47 30.77 1311+00 30.19 33.19 33.04 30.39 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-10 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1312+00 30.18 33.18 33.03 30.38 1364+00 29.71 32.71 32.51 29.92 1313+00 30.17 33.17 33.02 30.37 1365+00 29.70 32.70 32.50 29.91 1314+00 30.16 33.16 33.01 30.36 1366+00 29.69 32.69 32.49 29.90 1315+00 30.15 33.15 33.00 30.35 1367+00 29.69 32.69 32.48 29.90 1316+00 30.14 33.14 32.99 30.34 1368+00 29.68 32.68 32.48 29.89 1317+00 30.13 33.13 32.98 30.33 1369+00 29.67 32.67 32.47 29.88 1318+00 30.13 33.13 32.97 30.32 1370+00 29.66 32.66 32.46 29.87 1319+00 30.12 33.12 32.96 30.31 1371+00 29.65 32.65 32.45 29.86 1320+00 30.11 33.11 32.95 30.30 1372+00 29.64 32.64 32.44 29.85 1321+00 30.10 33.10 32.94 30.30 1373+00 29.64 32.64 32.43 29.85 1322+00 30.09 33.09 32.94 30.29 1374+00 29.63 32.63 32.42 29.84 1323+00 30.08 33.08 32.93 30.28 1375+00 29.62 32.62 32.41 29.83 1324+00 30.08 33.08 32.92 30.28 1376+00 29.61 32.61 32.41 29.82 1325+00 30.07 33.07 32.92 30.27 1377+00 29.61 32.61 32.40 29.82 1326+00 30.07 33.07 32.91 30.27 1378+00 29.60 32.60 32.39 29.81 1327+00 30.06 33.06 32.90 30.26 1379+00 29.59 32.59 32.38 29.80 1328+00 30.05 33.05 32.89 30.25 1380+00 29.58 32.58 32.37 29.79 1329+00 30.05 33.05 32.89 30.25 1381+00 29.58 32.58 32.36 29.79 1330+00 30.04 33.04 32.88 30.24 1382+00 29.57 32.57 32.36 29.78 1331+00 30.03 33.03 32.87 30.23 1383+00 29.56 32.56 32.35 29.77 1332+00 30.02 33.02 32.86 30.23 1384+00 29.55 32.55 32.34 29.76 1333+00 30.02 33.02 32.85 30.22 1385+00 29.54 32.54 32.33 29.75 1334+00 30.01 33.01 32.84 30.21 1386+00 29.54 32.54 32.32 29.75 1335+00 30.00 33.00 32.83 30.20 1387+00 29.53 32.53 32.32 29.74 1336+00 29.99 32.99 32.82 30.19 1388+00 29.52 32.52 32.31 29.73 1337+00 29.98 32.98 32.81 30.18 1389+00 29.51 32.51 32.30 29.72 1338+00 29.97 32.97 32.80 30.17 1390+00 29.51 32.51 32.29 29.72 1339+00 29.96 32.96 32.78 30.16 1391+00 29.50 32.50 32.28 29.71 1340+00 29.95 32.95 32.77 30.15 1392+00 29.49 32.49 32.28 29.70 1341+00 29.94 32.94 32.76 30.14 1393+00 29.48 32.48 32.27 29.69 1342+00 29.93 32.93 32.75 30.13 1394+00 29.48 32.48 32.26 29.68 1343+00 29.92 32.92 32.74 30.12 1395+00 29.47 32.47 32.25 29.68 1344+00 29.91 32.91 32.73 30.11 1396+00 29.46 32.46 32.24 29.67 1345+00 29.90 32.90 32.72 30.10 1397+00 29.45 32.45 32.23 29.66 1346+00 29.89 32.89 32.71 30.09 1398+00 29.44 32.44 32.22 29.65 1347+00 29.88 32.88 32.69 30.08 1399+00 29.44 32.44 32.22 29.64 1348+00 29.87 32.87 32.68 30.07 1400+00 29.43 32.43 32.21 29.63 1349+00 29.86 32.86 32.67 30.06 1401+00 29.42 32.42 32.20 29.63 1350+00 29.84 32.84 32.66 30.05 1402+00 29.41 32.41 32.19 29.62 1351+00 29.83 32.83 32.65 30.04 1403+00 29.40 32.40 32.18 29.61 1352+00 29.82 32.82 32.64 30.03 1404+00 29.39 32.39 32.17 29.60 1353+00 29.81 32.81 32.63 30.02 1405+00 29.38 32.38 32.16 29.59 1354+00 29.80 32.80 32.62 30.01 1406+00 29.37 32.37 32.15 29.58 1355+00 29.79 32.79 32.60 30.00 1407+00 29.37 32.37 32.14 29.57 1356+00 29.78 32.78 32.59 29.99 1408+00 29.36 32.36 32.13 29.56 1357+00 29.78 32.78 32.58 29.98 1409+00 29.35 32.35 32.12 29.55 1358+00 29.77 32.77 32.57 29.98 1410+00 29.34 32.34 32.11 29.54 1359+00 29.76 32.76 32.56 29.97 1411+00 29.33 32.33 32.10 29.54 1360+00 29.75 32.75 32.55 29.96 1412+00 29.32 32.32 32.10 29.53 1361+00 29.74 32.74 32.54 29.95 1413+00 29.31 32.31 32.09 29.52 1362+00 29.73 32.73 32.53 29.94 1414+00 29.31 32.31 32.08 29.51 1363+00 29.72 32.72 32.52 29.93 1415+00 29.30 32.30 32.07 29.50 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-11 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1416+00 29.29 32.29 32.06 29.49 1468+00 28.79 31.79 31.51 29.00 1417+00 29.28 32.28 32.05 29.48 1469+00 28.78 31.78 31.51 29.00 1418+00 29.25 32.25 32.02 29.46 1470+00 28.78 31.78 31.50 28.99 1419+00 29.24 32.24 32.00 29.44 1471+00 28.77 31.77 31.49 28.99 1420+00 29.22 32.22 31.98 29.43 1472+00 28.77 31.77 31.49 28.98 1421+00 29.20 32.20 31.96 29.41 1473+00 28.76 31.76 31.48 28.97 1422+00 29.19 32.19 31.94 29.39 1474+00 28.75 31.75 31.47 28.97 1423+00 29.17 32.17 31.92 29.38 1475+00 28.74 31.74 31.45 28.95 1424+00 29.15 32.15 31.90 29.36 1476+00 28.71 31.71 31.43 28.93 1425+00 29.13 32.13 31.88 29.35 1477+00 28.69 31.69 31.40 28.91 1426+00 29.12 32.12 31.86 29.33 1478+00 28.67 31.67 31.37 28.89 1427+00 29.10 32.10 31.84 29.32 1479+00 28.64 31.64 31.34 28.86 1428+00 29.09 32.09 31.82 29.30 1480+00 28.62 31.62 31.32 28.84 1429+00 29.08 32.08 31.82 29.30 1481+00 28.60 31.60 31.29 28.82 1430+00 29.07 32.07 31.81 29.29 1482+00 28.57 31.57 31.26 28.80 1431+00 29.07 32.07 31.81 29.29 1483+00 28.55 31.55 31.23 28.78 1432+00 29.06 32.06 31.80 29.28 1484+00 28.55 31.55 31.23 28.77 1433+00 29.06 32.06 31.79 29.28 1485+00 28.55 31.55 31.24 28.77 1434+00 29.05 32.05 31.79 29.27 1486+00 28.55 31.55 31.24 28.78 1435+00 29.05 32.05 31.78 29.27 1487+00 28.55 31.55 31.24 28.78 1436+00 29.04 32.04 31.78 29.26 1488+00 28.56 31.56 31.25 28.78 1437+00 29.04 32.04 31.77 29.26 1489+00 28.56 31.56 31.25 28.78 1438+00 29.04 32.04 31.77 29.25 1490+00 28.56 31.56 31.25 28.78 1439+00 29.03 32.03 31.77 29.25 1491+00 28.56 31.56 31.26 28.78 1440+00 29.03 32.03 31.77 29.25 1492+00 28.57 31.57 31.26 28.79 1441+00 29.03 32.03 31.77 29.25 1493+00 28.57 31.57 31.26 28.79 1442+00 29.03 32.03 31.77 29.24 1494+00 28.57 31.57 31.26 28.79 1443+00 29.03 32.03 31.77 29.24 1495+00 28.57 31.57 31.26 28.78 1444+00 29.03 32.03 31.77 29.24 1496+00 28.56 31.56 31.26 28.78 1445+00 29.03 32.03 31.77 29.24 1497+00 28.56 31.56 31.26 28.78 1446+00 29.02 32.02 31.77 29.23 1498+00 28.56 31.56 31.26 28.78 1447+00 29.02 32.02 31.77 29.23 1499+00 28.56 31.56 31.26 28.77 1448+00 29.01 32.01 31.76 29.22 1500+00 28.56 31.56 31.26 28.77 1449+00 29.01 32.01 31.75 29.21 1501+00 28.56 31.56 31.26 28.77 1450+00 29.00 32.00 31.74 29.21 1502+00 28.56 31.56 31.26 28.77 1451+00 28.99 31.99 31.73 29.20 1503+00 28.55 31.55 31.26 28.76 1452+00 28.98 31.98 31.72 29.19 1504+00 28.55 31.55 31.25 28.76 1453+00 28.97 31.97 31.71 29.18 1505+00 28.54 31.54 31.24 28.75 1454+00 28.96 31.96 31.70 29.17 1506+00 28.54 31.54 31.24 28.74 1455+00 28.96 31.96 31.70 29.17 1507+00 28.53 31.53 31.23 28.74 1456+00 28.95 31.95 31.69 29.16 1508+00 28.52 31.52 31.22 28.73 1457+00 28.93 31.93 31.67 29.14 1509+00 28.52 31.52 31.22 28.72 1458+00 28.92 31.92 31.65 29.13 1510+00 28.51 31.51 31.21 28.71 1459+00 28.90 31.90 31.64 29.11 1511+00 28.50 31.50 31.20 28.71 1460+00 28.89 31.89 31.62 29.10 1512+00 28.50 31.50 31.20 28.70 1461+00 28.87 31.87 31.60 29.08 1513+00 28.49 31.49 31.19 28.69 1462+00 28.86 31.86 31.59 29.07 1514+00 28.48 31.48 31.18 28.69 1463+00 28.84 31.84 31.57 29.05 1515+00 28.48 31.48 31.18 28.68 1464+00 28.83 31.83 31.55 29.04 1516+00 28.47 31.47 31.17 28.67 1465+00 28.81 31.81 31.54 29.03 1517+00 28.47 31.47 31.17 28.67 1466+00 28.80 31.80 31.52 29.02 1518+00 28.46 31.46 31.16 28.66 1467+00 28.80 31.80 31.52 29.01 1519+00 28.45 31.45 31.16 28.65 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-12 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1520+00 28.45 31.45 31.15 28.65 1572+00 28.00 31.00 30.65 28.21 1521+00 28.44 31.44 31.14 28.64 1573+00 27.99 30.99 30.64 28.20 1522+00 28.44 31.44 31.14 28.64 1574+00 27.98 30.98 30.63 28.19 1523+00 28.43 31.43 31.13 28.63 1575+00 27.97 30.97 30.62 28.18 1524+00 28.42 31.42 31.12 28.62 1576+00 27.96 30.96 30.61 28.17 1525+00 28.42 31.42 31.12 28.61 1577+00 27.95 30.95 30.60 28.16 1526+00 28.41 31.41 31.11 28.61 1578+00 27.95 30.95 30.59 28.15 1527+00 28.40 31.40 31.10 28.60 1579+00 27.94 30.94 30.58 28.14 1528+00 28.39 31.39 31.09 28.59 1580+00 27.93 30.93 30.57 28.14 1529+00 28.39 31.39 31.08 28.58 1581+00 27.92 30.92 30.56 28.13 1530+00 28.38 31.38 31.08 28.58 1582+00 27.91 30.91 30.54 28.12 1531+00 28.37 31.37 31.07 28.57 1583+00 27.90 30.90 30.53 28.11 1532+00 28.36 31.36 31.06 28.56 1584+00 27.89 30.89 30.52 28.10 1533+00 28.36 31.36 31.05 28.55 1585+00 27.87 30.87 30.50 28.08 1534+00 28.35 31.35 31.04 28.55 1586+00 27.86 30.86 30.49 28.07 1535+00 28.34 31.34 31.03 28.54 1587+00 27.85 30.85 30.48 28.06 1536+00 28.33 31.33 31.02 28.53 1588+00 27.84 30.84 30.46 28.05 1537+00 28.32 31.32 31.02 28.52 1589+00 27.83 30.83 30.45 28.04 1538+00 28.31 31.31 31.01 28.51 1590+00 27.82 30.82 30.44 28.03 1539+00 28.31 31.31 31.00 28.50 1591+00 27.81 30.81 30.43 28.02 1540+00 28.30 31.30 30.99 28.49 1592+00 27.80 30.80 30.42 28.02 1541+00 28.29 31.29 30.98 28.48 1593+00 27.80 30.80 30.42 28.01 1542+00 28.28 31.28 30.97 28.48 1594+00 27.79 30.79 30.42 28.01 1543+00 28.27 31.27 30.96 28.47 1595+00 27.79 30.79 30.41 28.00 1544+00 28.26 31.26 30.95 28.46 1596+00 27.79 30.79 30.41 28.00 1545+00 28.25 31.25 30.94 28.45 1597+00 27.78 30.78 30.40 28.00 1546+00 28.24 31.24 30.92 28.44 1598+00 27.78 30.78 30.40 27.99 1547+00 28.23 31.23 30.91 28.43 1599+00 27.78 30.78 30.40 27.99 1548+00 28.22 31.22 30.90 28.42 1600+00 27.77 30.77 30.39 27.98 1549+00 28.21 31.21 30.88 28.41 1601+00 27.77 30.77 30.39 27.98 1550+00 28.20 31.20 30.87 28.40 1602+00 27.77 30.77 30.39 27.98 1551+00 28.18 31.18 30.86 28.38 1603+00 27.76 30.76 30.38 27.97 1552+00 28.17 31.17 30.85 28.37 1604+00 27.76 30.76 30.38 27.97 1553+00 28.16 31.16 30.83 28.36 1605+00 27.75 30.75 30.37 27.96 1554+00 28.15 31.15 30.82 28.35 1606+00 27.75 30.75 30.37 27.96 1555+00 28.14 31.14 30.81 28.35 1607+00 27.74 30.74 30.36 27.95 1556+00 28.13 31.13 30.80 28.34 1608+00 27.74 30.74 30.36 27.95 1557+00 28.12 31.12 30.79 28.33 1609+00 27.73 30.73 30.35 27.94 1558+00 28.11 31.11 30.78 28.32 1610+00 27.73 30.73 30.35 27.94 1559+00 28.11 31.11 30.77 28.31 1611+00 27.72 30.72 30.34 27.93 1560+00 28.10 31.10 30.76 28.30 1612+00 27.72 30.72 30.33 27.92 1561+00 28.09 31.09 30.75 28.29 1613+00 27.71 30.71 30.32 27.92 1562+00 28.08 31.08 30.74 28.28 1614+00 27.70 30.70 30.32 27.91 1563+00 28.07 31.07 30.73 28.27 1615+00 27.70 30.70 30.31 27.90 1564+00 28.06 31.06 30.72 28.27 1616+00 27.69 30.69 30.30 27.90 1565+00 28.05 31.05 30.71 28.26 1617+00 27.68 30.68 30.30 27.89 1566+00 28.05 31.05 30.70 28.25 1618+00 27.67 30.67 30.29 27.88 1567+00 28.04 31.04 30.69 28.24 1619+00 27.67 30.67 30.28 27.88 1568+00 28.03 31.03 30.68 28.24 1620+00 27.66 30.66 30.28 27.87 1569+00 28.02 31.02 30.68 28.23 1621+00 27.66 30.66 30.28 27.87 1570+00 28.02 31.02 30.67 28.22 1622+00 27.66 30.66 30.27 27.87 1571+00 28.01 31.01 30.66 28.22 1623+00 27.66 30.66 30.27 27.87 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-13 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1624+00 27.66 30.66 30.27 27.86 1676+00 27.31 30.75 29.89 27.88 1625+00 27.66 30.66 30.27 27.86 1677+00 27.29 30.73 29.87 27.86 1626+00 27.65 30.65 30.27 27.86 1678+00 27.28 30.71 29.85 27.84 1627+00 27.65 30.65 30.27 27.86 1679+00 27.26 30.69 29.83 27.82 1628+00 27.65 30.65 30.27 27.86 1680+00 27.24 30.67 29.81 27.80 1629+00 27.65 30.65 30.27 27.85 1681+00 27.22 30.65 29.79 27.78 1630+00 27.65 30.65 30.26 27.85 1682+00 27.21 30.63 29.76 27.75 1631+00 27.64 30.64 30.26 27.84 1683+00 27.19 30.60 29.74 27.73 1632+00 27.64 30.64 30.25 27.84 1684+00 27.17 30.59 29.73 27.72 1633+00 27.63 30.65 30.25 27.84 1685+00 27.17 30.57 29.72 27.70 1634+00 27.63 30.67 30.25 27.83 1686+00 27.16 30.56 29.71 27.69 1635+00 27.63 30.68 30.24 27.83 1687+00 27.15 30.55 29.70 27.67 1636+00 27.62 30.70 30.24 27.82 1688+00 27.14 30.54 29.69 27.66 1637+00 27.62 30.71 30.24 27.82 1689+00 27.13 30.53 29.68 27.64 1638+00 27.61 30.72 30.23 27.81 1690+00 27.13 30.52 29.67 27.63 1639+00 27.61 30.74 30.23 27.81 1691+00 27.12 30.51 29.66 27.61 1640+00 27.60 30.75 30.22 27.80 1692+00 27.11 30.49 29.65 27.60 1641+00 27.60 30.76 30.21 27.80 1693+00 27.10 30.48 29.64 27.58 1642+00 27.59 30.77 30.21 27.79 1694+00 27.09 30.47 29.63 27.57 1643+00 27.58 30.78 30.20 27.78 1695+00 27.09 30.46 29.62 27.55 1644+00 27.58 30.79 30.19 27.78 1696+00 27.08 30.45 29.62 27.54 1645+00 27.57 30.80 30.18 27.77 1697+00 27.08 30.44 29.62 27.53 1646+00 27.56 30.81 30.18 27.76 1698+00 27.07 30.44 29.61 27.51 1647+00 27.56 30.83 30.17 27.75 1699+00 27.07 30.43 29.61 27.50 1648+00 27.55 30.84 30.16 27.75 1700+00 27.06 30.42 29.60 27.49 1649+00 27.54 30.85 30.15 27.74 1701+00 27.06 30.41 29.60 27.48 1650+00 27.54 30.86 30.15 27.73 1702+00 27.06 30.40 29.59 27.46 1651+00 27.53 30.87 30.14 27.73 1703+00 27.05 30.39 29.59 27.45 1652+00 27.52 30.88 30.13 27.72 1704+00 27.05 30.39 29.58 27.44 1653+00 27.52 30.89 30.12 27.72 1705+00 27.05 30.38 29.58 27.43 1654+00 27.51 30.90 30.12 27.71 1706+00 27.04 30.38 29.58 27.42 1655+00 27.50 30.91 30.11 27.77 1707+00 27.04 30.37 29.58 27.41 1656+00 27.50 30.93 30.10 27.84 1708+00 27.04 30.37 29.58 27.40 1657+00 27.49 30.94 30.10 27.90 1709+00 27.04 30.37 29.58 27.40 1658+00 27.48 30.95 30.09 27.97 1710+00 27.04 30.36 29.58 27.39 1659+00 27.48 30.96 30.08 28.03 1711+00 27.04 30.36 29.58 27.38 1660+00 27.47 30.97 30.07 28.10 1712+00 27.04 30.35 29.58 27.37 1661+00 27.46 30.96 30.07 28.16 1713+00 27.04 30.35 29.58 27.36 1662+00 27.46 30.95 30.06 28.15 1714+00 27.04 30.34 29.58 27.36 1663+00 27.45 30.94 30.05 28.13 1715+00 27.03 30.33 29.57 27.35 1664+00 27.44 30.93 30.04 28.11 1716+00 27.03 30.33 29.57 27.35 1665+00 27.43 30.92 30.03 28.09 1717+00 27.03 30.32 29.57 27.35 1666+00 27.43 30.90 30.03 28.07 1718+00 27.02 30.31 29.56 27.34 1667+00 27.42 30.89 30.02 28.05 1719+00 27.02 30.31 29.56 27.34 1668+00 27.41 30.88 30.01 28.03 1720+00 27.01 30.30 29.55 27.33 1669+00 27.40 30.87 30.00 28.02 1721+00 27.01 30.29 29.54 27.33 1670+00 27.40 30.86 29.99 28.00 1722+00 27.00 30.28 29.54 27.32 1671+00 27.39 30.85 29.99 27.98 1723+00 26.99 30.27 29.53 27.31 1672+00 27.38 30.84 29.98 27.96 1724+00 26.99 30.26 29.52 27.31 1673+00 27.37 30.82 29.96 27.94 1725+00 26.98 30.25 29.52 27.30 1674+00 27.35 30.80 29.94 27.92 1726+00 26.98 30.24 29.51 27.29 1675+00 27.33 30.78 29.92 27.90 1727+00 26.97 30.23 29.50 27.29 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-14 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1728+00 26.96 30.22 29.50 27.28
1729+00 26.96 30.21 29.49 27.28
1730+00 26.97 30.21 29.50 27.29
1731+00 26.95 30.19 29.48 27.27
1732+00 26.94 30.18 29.47 27.26
1733+00 26.93 30.17 29.46 27.25
1734+00 26.92 30.15 29.45 27.25
1735+00 26.91 30.14 29.44 27.24
1736+00 26.91 30.13 29.43 27.23
1737+00 26.90 30.12 29.42 27.22
1738+00 26.89 30.11 29.41 27.21
1739+00 26.88 30.09 29.40 27.20
1740+00 26.87 30.08 29.39 27.19
1741+00 26.86 30.07 29.38 27.18
1742+00 26.85 30.05 29.37 27.17
1743+00 26.84 30.04 29.36 27.16
1744+00 26.83 30.02 29.34 27.15
1745+00 26.82 30.01 29.33 27.14
1746+00 26.81 30.00 29.32 27.13
1747+00 26.80 29.98 29.31 27.12
1748+00 26.79 29.97 29.30 27.11
1749+00 26.78 29.95 29.29 27.10
1750+00 26.77 29.94 29.27 27.09
1751+00 26.76 29.93 29.26 27.08
1752+00 26.75 29.91 29.25 27.07
1753+00 26.74 29.90 29.24 27.07
1754+00 26.74 29.89 29.24 27.06
1755+00 26.73 29.89 29.23 27.06
1756+00 26.73 29.88 29.23 27.06
1757+00 26.72 29.87 29.22 27.05
1758+00 26.72 29.86 29.22 27.05
1759+00 26.71 29.85 29.21 27.04
1760+00 26.71 29.85 29.21 27.04
1761+00 26.71 29.84 29.20 27.03
1762+00 26.70 29.83 29.20 27.03
1763+00 26.70 29.82 29.20 27.03
1764+00 26.69 29.81 29.19 27.02
1765+00 26.69 29.81 29.19 27.02
1766+00 26.68 29.80 29.18 27.01
1767+00 26.68 29.79 29.17 27.00
1768+00 26.67 29.78 29.16 27.00
1769+00 26.66 29.77 29.16 26.99
1770+00 26.65 29.75 29.15 26.98
Appendix D.

American River South ULDC Due
Diligence, Geotech - GEI
ULDC Geotechnical Findings Report
American River South Levee System –
Sacramento River East Levee: Station
1080+00 to 1150+00, Station 1185+00 to
1206+00, Station 1285+75 to 1418+00, and
Station 1534+40 to 1640+00
Sacramento County, California
Submitted to:

Sacramento Area Flood Control Agency
1325 J Street, Suite 1700
Sacramento, CA 95814
Submitted by:

GEI Consultants, Inc.
180 Grand Avenue, Suite 950
Oakland, CA 94612
510.350.2900
April 2025
Project No. 1804694 ________________________________________ Alberto Pujol, P.E., G.E.

Senior Vice President
________________________________________
Emilie Singleton, P.E., PMP
Senior Engineer
GEI Consultants, Inc. i
April 15, 2025
Project No. 1804694
VIA EMAIL: [email protected]
Mr. Dan Tibbitts, P.E.

Principal Engineer
Sacramento Area Flood Control Agency
1325 J Street, Suite 1700
Sacramento, CA 95814
Subject: ULDC Geotechnical Finding Report
American River South Levee System – Sacramento River East Levee: Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00
Sacramento Area Flood Control Agency
Sacramento County, California
Dear Mr. Tibbitts:

This report presents GEI’s geotechnical evaluation of the existing Sacramento River East Levee (SREL) as part of the American River South Levee System for the following segments of levee:
⚫ Station 1080+00 to 1150+00
⚫ Station 1185+00 to 1206+00
⚫ Station 1285+75 to 1418+00
⚫ Station 1534+40 to 1640+00
GEI’s evaluation was conducted at the request of the Sacramento Area Flood Control Agency (SAFCA) to ascertain levee compliance with the geotechnical criteria specified in the following five sections of the California Department of Water Resources (DWR) Urban Levee Design Criteria (ULDC) (DWR, 2012):
⚫ Section 7.3, Soil Sampling, Testing, and Logging
⚫ Section 7.4, Slope Stability for Intermittently Loaded Levees ⚫ Section 7.5, Underseepage for Intermittently Loaded Levees ⚫ Section 7.8, Levee Geometry
⚫ Section 7.9, Interfaces and Transitions
Other sections of the ULDC (DWR, 2012) are not addressed in this report and are being addressed by other consultants.

GEI Consultants, Inc. ii
If you have quesons regarding this report or if we may be of further assistance, please contact the undersigned.

Sincerely,
GEI Consultants, Inc.

Alberto Pujol, P.E., G.E.

Senior Vice President
Emilie Singleton, P.E., PMP
Senior Engineer
cc: Mr. Pro Mitra, P.E./MBK Engineers ([email protected]) Ms. Becky Money, P.E., G.E./MBK Engineers ([email protected]) ULDC Geotechnical Findings Report
American River South Levee System – Sacramento River East Levee April 2025
GEI Consultants, Inc. i
Table of Contents
Acronyms and Abbreviations iii

1. Introduction 1

1.1. Project Background 1

1.2. Project Stationing and Datums 1

1.3. Levee Background and Construction History 2

1.4. Reaches 4

1.5. Methodology and Reference Documentation 5

1.6. Criteria 7

1.7. Water Surface Elevations 7

1.8. Levee Site Visit 7

1.8.1. Objectives 8

1.8.2. Observations 8

1.9. Past Performance 8

2. ULDC Geotechnical Criteria Review 9

2.1. ULDC Section 7.3 – Soil Sampling, Testing, and Logging 9

2.1.1. ULDC Requirements 9

2.1.2. Evaluation 10

2.1.3. Conclusion 14

2.2. ULDC Section 7.4 – Slope Stability for Intermittently Loaded Levees 14

2.2.1. ULDC Requirements 14

2.2.2. Evaluation 15

2.2.3. Conclusion 16

2.3. ULDC Section 7.5 – Underseepage for Intermittently Loaded Levees 16

2.3.1. ULDC Requirements 16

2.3.2. Evaluation 17

2.3.3. Conclusion 18

2.4. ULDC Section 7.8 – Levee Geometry 18

2.4.1. ULDC Requirements 18

2.4.2. Evaluation 20

2.4.3. Conclusion 21

2.5. ULDC Section 7.9 – Interfaces and Transitions 21

2.5.1. ULDC Requirements 21

2.5.2. Existing Transitions 21

2.5.2.1. Transitions within SREL from Station 1080+00 to 1150+00 22

2.5.2.2. Transitions within SREL from Station 1185+00 to 1206+00 23 ULDC Geotechnical Findings Report
American River South Levee System – Sacramento River East Levee April 2025
GEI Consultants, Inc. ii

2.5.2.3. Transitions within SREL from Station 1285+75 to 1418+00 23

2.5.2.4. Transitions within SREL from Station 1534+40 to 1640+00 23

2.5.3. Conclusion 24

3. Summary of Results 25

4. Limitations 26

5. References 27
List of Tables
Table 1-1. Constructed Seepage and Stability Improvements Within and Adjacent to Subject SREL Segments 3
Table 1-2. Geotechnical Analysis Levee Reaches and Stationing 4 Table 2-1. Summary of Exploration Counts for SREL Station 1080+00 to 1150+00 (1.33 Miles) 11 Table 2-2. Summary of Exploration Counts for SREL Station 1185+00 to 1206+00 (0.40 miles) 12 Table 2-3. Summary of Exploration Counts for SREL Station 1285+75 to 1418+00 (2.50 Miles) 12 Table 2-4. Summary of Exploration Counts for SREL Station 1534+40 to 1640+00 (2.00 Miles) 13 Table 2-5. Minimum ULDC Factors of Safety for Slope Stability 15 Table 2-6. ULDC Allowable Underseepage Exist Gradients 17 Table 2-7. Reproduction of ULDC Table 7-1 – Summary of Existing Levee Geometry Guidance 19 Table 3-1. Levee Segments that Meet Geotechnical Aspects of ULDC Criteria 25 Figures
Figure 1 – ULDC Certification Levee Extents
Figure 2 – Reaches and Cross Sections (Sheet 1 of 4)
Figure 3 – Reaches and Cross Sections (Sheet 2 of 4)
Figure 4 – Reaches and Cross Sections (Sheet 3 of 4)
Figure 5 – Reaches and Cross Sections (Sheet 4 of 4)
Appendices
Appendix A ULDC Water Surface Elevations
Appendix B Summary Tables of Available Explorations
Appendix C Seepage and Stability Analysis Results Summary Appendix D Levee Geometry
ULDC Geotechnical Findings Report
American River South Levee System – Sacramento River East Levee April 2025
GEI Consultants, Inc. iii
Acronyms and Abbreviations
ARS American River South
CVFPB Central Valley Flood Protection Board
DMM Deep Mixing Method
DWR California Department of Water Resources
DWSE Design Water Surface Elevation
EM Engineer Manual
ETL Engineer Technical Letter
FEMA Federal Emergency Management Agency
GEI GEI Consultants, Inc.

HDR HDR Engineering, Inc.

HEM Helicopter-Borne Electromagnetic
HTOL Hydraulic Top of Levee
LMA Local Maintaining Agency
NAVD88 North American Vertical Datum of 1988
MA 9 Maintenance Area 9
MBK MBK Engineers
MTOL Minimum Top of Levee
P1GDR Phase 1 Geotechnical Data Report
SAFCA Sacramento Area Flood Control Agency
SGDR Supplemental Geotechnical Data Report

SPK SOP
USACE Sacramento District’s Geotechnical Levee Practice Standard Operating Procedure
SB Soil-Bentonite
SCB Soil-Cement-Bentonite
SCCB Slag-Cement-Cement-Bentonite
SPT Standard Penetration Test
SREL Sacramento River East Levee
SRELIP Sacramento River East Levee Improvement Project
ULDC Urban Levee Design Criteria
ULE Urban Levee Evaluation
URS URS Corporation
U.S. United States
USACE United States Army Corps of Engineers
WRDA Water Resources Development Act
WSE Water Surface Elevation
ULDC Geotechnical Findings Report
American River South Levee System – Sacramento River East Levee April 2025
GEI Consultants, Inc. 1

1. Introduction

1.1. Project Background
This geotechnical findings report documents GEI Consultants, Inc.’s (GEI’s) evaluation of the segments of levees listed below and shown in Figure 1. These levees have a combined length of 6.23 miles and are a part of the Sacramento River East Levee (SREL). Sacramento River East Levee:
⚫ Station 1080+00 to 1150+00
⚫ Station 1185+00 to 1206+00
⚫ Station 1285+75 to 1418+00
⚫ Station 1534+40 to 1640+00
GEI’s evaluation was conducted at the request of the Sacramento Area Flood Control Agency (SAFCA) to ascertain levee compliance with the geotechnical criteria specified in the following five sections of the California Department of Water Resources (DWR) Urban Levee Design Criteria (ULDC) (DWR, 2012):
⚫ Section 7.3 Soil Sampling, Testing, and Logging
⚫ Section 7.4 Slope Stability for Intermittently Loaded Levees ⚫ Section 7.5 Underseepage for Intermittently Loaded Levees ⚫ Section 7.8 Levee Geometry
⚫ Section 7.9 Interfaces and Transitions
Other sections of the ULDC are not addressed in this report and are being addressed by other consultants.

This report should be considered a “snapshot” of the condition of the levee system at this time.

Additional study and work may be needed due to the passage of time or if ULDC requirements change.

1.2. Project Stationing and Datums
Project stationing used in this report is based on DWR stationing developed originally for the Urban Levee Evaluation (ULE) project. Elevation references in this report are in feet and are based on the North American Vertical Datum of 1988 (NAVD88).

ULDC Geotechnical Findings Report
American River South Levee System – Sacramento River East Levee April 2025
GEI Consultants, Inc. 2

1.3. Levee Background and Construction History
The location of the SREL Project is presented on Figure 1. The SREL in the Project area is an earthen embankment originally constructed in stages from the mid-1800s to the early-1900s. At that time, levees were often constructed on the flood plain by raising the existing natural levee on top of the riverbank, without much setback from the river channel.

Levee construction around the City of Sacramento began around 1851 as hand-built earthen mounds following the flood of 1850 (Sacramento History Directory for the Year 1851). Levee construction records for the SREL are not available. As described in the United States Army Corps of Engineers (USACE) General Reevaluation Report (USACE, 2015), the Sacramento River Flood Control Project, including the portion within the greater Sacramento urban area, was constructed using either a clamshell dredge or a suction dredge retrieving material from the adjacent river channel and piling it along the levee alignment. Levees constructed of dredged sediments from the river channel are commonly sandy and have been associated with the occurrence of through seepage and shallow, surficial underseepage. A two-mile length of levee extending from about R Street to Riverside Boulevard was likely constructed or modified by the Southern Pacific Railroad in the early 1900’s to connect Sacramento to the town of Isleton by rail. In this reach, a portion of the levee is set back from the river and the levee is generally wider than other levee sections.

Today, the SREL system reduces flood risk to a heavily urbanized area with residential, recreation, and industrial properties. Backyards and other structures are at or near the landside levee toe along significant stretches. Woody vegetation has been allowed to establish on the levee in many areas.

Manmade encroachments (e.g., railroad tracks, roadways, fences, retaining walls, stairs, irrigation systems, boat docks, etc.) and penetrations (pipelines and conduits) are also common in the levee.

Erosion and waterside slope raveling issues along limited reaches of levee have been documented in past performance records.

Following the 1986 flood, the United States (U.S.) Congress directed USACE to investigate additional means for reducing flood risk to the City of Sacramento. Soon after, approximately 20 miles of shallow cutoff walls were constructed along SREL from Powerline Road in Natomas to Freeport to address through-seepage. During the last three decades, the USACE and SAFCA have designed and constructed additional improvements along several portions of the SREL primarily to address underseepage issues and lingering through seepage issues identified through past performance and levee evaluations. The additional improvements have included deep seepage cutoff walls, relief wells, seepage and stability berms, and erosion protection. The levee repair design is constrained by flood control easements, limited levee access, residences and other structures at or near the landside toe, and limited working space along the waterside berm, if present. Table 1-1 below summarizes the extents of the constructed seepage and stability improvements within the subject SREL segments. Cutoff wall improvements have included jet grout walls, soil-bentonite (SB) walls, slag-cement-cement-bentonite (SCCB) walls, soilcement-bentonite (SCB) walls, and deep mixing method (DMM) walls. Transitions, including overlaps and areas without improvements, are discussed in Section 2.5.2.

The City of Sacramento is the local maintaining agency (LMA) for the northern portion of the SREL from the confluence of the American River (Station 1000+00) to Sutterville Road (Approximately ULDC Geotechnical Findings Report
American River South Levee System – Sacramento River East Levee April 2025
GEI Consultants, Inc. 3
Station 1215+00) and DWR Maintenance Area 9 (MA 9) is the LMA for the southern portion of the SREL within the Project area. The LMAs are responsible for operations and maintenance of the levee and perform the necessary flood-fighting duties during high-water events.

Table 1-1. Constructed Seepage and Stability Improvements Within and Adjacent to Subject SREL Segments
Reach 1 Construction Constructed Improvement Stations (ft) 2 2 USACE 2019 (ARCF Contract 1) Drained stability berm 1086+18 1090+33 4-1 USACE 2021 (SREL C2) Jet Grout Cutoff Wall 1093+50 1098+50 4-1 USACE 2021 (SREL C2) Relief Well Modifications 1095+00 1097+00 4 2006 Drained Seepage Berm 1095+54 1102+07
4 2006 Relief Wells 1095+54 1102+07
4-2 USACE 2020 (SREL C1) Drained Stability Berm 1096+91 1102+21 5-2 and 6-1 USACE 2021 (SREL C2) 3Jet Grout Cutoff Wall 1105+00 1112+40 6-1 USACE 2021 (SREL C2) Jet Grout Cutoff Wall 1114+00 1116+15 6-2 and 7-1 USACE 2020 (SREL C1) SCCB Cutoff Wall 1116+00 1125+50 7-2a USACE 2020 (SREL C1) Seepage Berm 1124+95 1130+17
7, 8, 9 USACE 1991-93 (Phase II) SCB Cutoff Wall 1125+01 1224+65 9 USACE 2020 (SREL C1) SB Cutoff Wall 1199+00 1207+75
Upstream of 12 SAFCA 2003 DMM Cutoff Wall 1261+53 1285+50 12, 13, 14, and 15 USACE 1990/91 (Phase I) SCB Cutoff Wall 1245+97 1352+10 12 and 13a USACE 2020 (SREL C1) DMM Cutoff Wall) 1282+90 1300+80 13b USACE 2021 (SREL C2) SB Cutoff Wall 1300+30 1310+00 15, 16, and 17 USACE 2021 (SREL C2) SB Cutoff Wall 1336+00 1398+60 15, 16, 17, 18, 19,
24, 25, 26, L-2 and
27 USACE 1991-93 (Phase II) SCB Cutoff Wall 1351+90 1756+03 17 USACE 2021 (SREL C2) SCCB Cutoff Wall 1398+30 1407+50 18, 19 USACE 2006 DMM Cutoff Wall 1406+99 1424+51
23 (Upstream of 24) SAFCA 2003 DMM Cutoff Wall 1530+37 1534+35 23 (Upstream of 24) SAFCA 2003 Relief Wells 1530+37 1534+35 24 USACE 2020 (SREL C1) DMM Cutoff Wall 1534+00 1547+50 24, 25, and 26 USACE 2020 (SREL C1) SB Cutoff Wall 1547+20 1557+50 26 and L-2 USACE 2020 (SREL C1) SCCB Cutoff Wall 1557+20 1571+90 L-2 and 27 USACE 2020 (SREL C1) SB Cutoff Wall 1571+60 1640+00 Notes:

1. Reach designations are described in Section 1.4.

2. Stationing for improvements prior to 2019 are estimated based on available information. Stationing for improvements constructed between 2019 and 2021 based on Construction Completion Reports.

3. Cutoff wall between Station 1105+00 and 1105+55 was installed under SREL Contract 4 (2024) due to difficulty in locating a PG&E gas main during 2021 construction.

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1.4. Reaches
To complete the geotechnical analyses referenced in Section 2 and described in the reference reports listed in Section 1.5, the levee segments were subdivided into reaches. Reach limits were selected so that the physical and geotechnical characteristics within each reach were generally consistent, allowing geotechnical evaluations for each reach using one or more critical analytic cross sections. In the reference reports, site characterizations of the levees and analysis results are presented by reach as well as by station. Table 1-2 shows the reach identifier names used in the reference reports and associated reach station limits. These reaches were originally developed by GEI for the SAFCA Levee Accreditation Project and documented in GEI’s Embankment and Foundation Stability Memorandum (GEI, 2016). Some reaches were further subdivided for the USACE Water Resources Development Act (WRDA) 2016 projects as documented in SREL Contract 1 and Contact 2 Design Documentation Reports (GEI, 2019 and GEI, 2020). Reach limits and analysis cross section locations are shown in Figures 2 through 5.

Table 1-2. Geotechnical Analysis Levee Reaches and Stationing Levee Reach ID Reach Start Stationing Reach End Stationing 1 1080+00 1085+00
2 1085+00 1090+50
3 1090+50 1094+50
4-1 1094+50 1096+75
4-2 1096+75 1102+00
5-1 1102+00 1104+00
5-2 1104+00 1110+00
6-1 1110+00 1117+00
6-2 1117+00 1119+80
7-1 1119+80 1125+50
7-2a 1125+50 1130+00
7-2b 1130+00 1150+00
8 1185+00 1199+00
9 1199+00 1206+00
12 1285+75 1291+50
13a 1291+50 1300+80
13b 1300+80 1310+00
14 1310+00 1336+00
15 1336+00 1373+00
16 1373+00 1391+50
17 1391+50 1407+50
18 1407+50 1414+50
19 1414+50 1418+00
24 1534+40 1550+00
25 1550+00 1554+50
26 1554+50 1570+00
KL Reach L-2 1570+00 1600+00
27 1600+00 1640+00
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1.5. Methodology and Reference Documentation
GEI’s geotechnical review involved examining the site investigations, geotechnical engineering analyses, construction records, and other information contained in the site-specific reports listed below. GEI relied on these documents in assessing compliance with the ULDC criteria. These reports have been previously published under separate cover and are listed in this report for reference.

SAFCA Levee Accreditation Project
⚫ GEI/HDR Engineering, Inc. (HDR), 2015a. “Supplemental Geotechnical Data Memorandum, Sacramento River East Levee Improvement Project (SRELIP), Revision 1.” October. ⚫ GEI/HDR, 2015b. “Alternatives Evaluation Memorandum, Sacramento River East Levee Improvement Project.” December 28.
⚫ GEI/HDR, 2016. “Embankment and Foundation Stability Memorandum, Sacramento River East Levee Improvement Project, Revision 1.” August.
⚫ GEI/HDR, 2017. Memorandum – “Levee Performance Reconnaissance, Sacramento River East Levee Improvement Project, Sacramento, California.” February 23. ⚫ GEI/HDR, 2018. “Draft Engineering Report, Sacramento River East Levee Improvement Project.” August.
⚫ Kleinfelder, Inc., 2013a. “Geotechnical Data Report, Sacramento River East Levee Downstream of American River, SAFCA FEMA Levee Accreditation (North Area Streams, American River, Sacramento River Downstream of American River, and Beach Lake Levee), Sacramento County, California.” June.
⚫ Kleinfelder, Inc., 2013b. “Problem Identification Report Sacramento River East Levee Downstream of American River, SAFCA FEMA Levee Accreditation (North Area Streams, American River, Sacramento River Downstream of American River, And Beach Lake Levee).

Sacramento County, California.” August.
⚫ Kleinfelder, Inc., 2014. “ULDC Geotechnical Results Summary Report, Sacramento River East Levee Downstream of American River, SAFCA FEMA Levee Accreditation (North Area Streams, American River, Sacramento River Downstream of American River, And Beach Lake Levee).

Sacramento County, California.” March.

WRDA 2016
⚫ GEI/HDR, 2019a. “Design Documentation Report, American River Common Features Project WRDA 2016, American River South (ARS) Basin Reach D, Contract 1 Drained Stability Berm.” March.
⚫ GEI/HDR, 2019b. “Addendum 1 to Supplemental Geotechnical Data Memorandum, Sacramento River East Levee.” August.
⚫ GEI/HDR, 2019c. “Final Design Documentation Report, American River Common Features 2016 Sacramento River East Levee – Contract 1.” November.

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⚫ GEI/HDR, 2019d. “Addendum 2 to Supplemental Geotechnical Data Memorandum, Sacramento River East Levee.” December.
⚫ GEI/HDR, 2020. “Final Design Documentation Report, American River Common Features 2016 Sacramento River East Levee – Contract 2.” October.
⚫ GEI/HDR, 2021a. “Addendum 3 to Supplemental Geotechnical Data Memorandum, Sacramento River East Levee.” January.
⚫ GEI/HDR, 2021b. “Construction Completion Report, American River Common Features Project WRDA 2016, ARS Basin Reach D, Contract 1 Drained Stability Berm.” July. ⚫ GEI/HDR, 2021c. “Construction Completion Report, American River Common Features 2016 Sacramento River East Levee – Contract 1.” July.
⚫ GEI/HDR, 2022. “Construction Completion Report, American River Common Features 2016 Sacramento River East Levee – Contract 2.” September.
⚫ Kleinfelder, Inc., 2020a. “Geotechnical Data Report, Geotechnical Characterization of Levee Material, Sacramento River East Levee – Stations 1104+00 to 1116+15, Sacramento, California.” September 2.
⚫ Kleinfelder, Inc., 2020b. “Environmental Field Exploration Summary Report, Characterization of Levee Material, Sacramento River East Levee – Stations 1093+50 to 1116+15, Sacramento, California.” October 2.
⚫ MBK, 2016. Technical Memorandum – “Determination of Design Water Surface Elevation for SAFCA Sacramento River East Levee Improvement Project.” September 14.

DWR Urban Levee Evaluation Program
⚫ URS Corporation (URS), 2008. “Phase 1 Geotechnical Data Report (P1GDR), Sacramento River Study Area, Urban Levee Geotechnical Evaluations Program, Contract 4600007418.” November. ⚫ URS, 2011. “Supplemental Geotechnical Data Report (SGDR), Sacramento River Study Area, Urban Levee Geotechnical Evaluations Program, Contract 4600007418.” September. ⚫ URS, 2014a. “Supplemental Geotechnical Data Report Addendum, Sacramento River Study Area, Urban Levee Evaluations Project, Contract 4600008101.” April. ⚫ URS, 2014b. “Geotechnical Evaluation Report Volume 1, Existing Conditions, Sacramento River Study Area, Urban Levee Evaluations Project, Contract 4600008101.” July. ⚫ URS, 2015. “Geotechnical Evaluation Report Volume 2, Remedial Alternatives, Sacramento River Study Area, Urban Levee Evaluations Project, Contract 4600008101.” January.

USACE General Reevaluation Report
⚫ USACE, 2013. “Geotechnical Office Report, American River Watershed Common Features Project General Reevaluation Report.” October.
⚫ USACE, 2015. “American River Watershed Common Features General Reevaluation Report.” December.

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1.6. Criteria
The purpose of this findings report is to review existing geotechnical information available for the subject levee segments to perform an evaluation as to whether these levees currently meet the geotechnical requirement of the ULDC. This geotechnical information is contained in the reports referenced in Section

1.5. This information was compared to applicable criteria from the following reference:
⚫ Urban Levee Design Criteria (ULDC), State of California Department of Water Resources, dated May 2012
Related regulatory criteria is contained in the following documents:
⚫ Engineer Manual (EM) 1110-2-1913, Design and Construction of Levees, USACE, April 2000, as amended by Engineer Technical Letter (ETL) 1110-2-569, Design Guidance for Levee Underseepage, USACE, May 2005.
⚫ USACE SPK-EDG, “Standard Operating Procedure 3, Geotechnical Levee Practice, U.S. Army Corps of Engineers, Sacramento District, Geotechnical Engineering Branch” dated May 2022 ⚫ U.S. Title 44 Code of Federal Regulations 65.10: Mapping of Areas Protected by Levee Systems.

1.7. Water Surface Elevations
The 200-year design water surface elevation (DWSE) profile and the hydraulic top of levee (HTOL) water surface elevation (WSE) profile used for the current ULDC evaluation were developed by MBK Engineers (MBK) in 2024 and documented in a Technical Memorandum (MBK, 2025). They are provided in tabular form at 100-foot intervals along the SREL in Table D-2 of the Technical Memorandum, which is included in Appendix A. These water surface elevation profiles are referred to herein as the 2024 200-year DWSE and HTOL WSEs.

The earlier WSE profiles used in the geotechnical evaluations for the subject SREL segments were also developed by MBK and are summarized in an MBK memorandum titled “Determination of the Design Water Surface Elevation for the SAFCA Sacramento River East Levee Improvement Project” dated September 2016 (MBK, 2016).

In all cases, the 2024 200-year DWSE and HTOL WSE are lower than the WSEs modeled in the existing analyses for the SAFCA Sacramento River East Levee Improvement Project referenced later in this report.

Our compliance evaluation summary was developed by comparing the previous geotechnical analysis results at the previous higher WSEs with the lower 2024 200-year and 2024 HTOL WSEs. Since the existing analyses met ULDC criteria at the previous higher WSEs, the existing analyses are considered to also meet criteria at the lower 2024 200-year and 2024 HTOL WSEs. This assessment is described further in Section 2 of this report.

1.8. Levee Site Visit
The GEI team (Alberto Pujol, Emilie Singleton, Kris Van Sant, and Nicole Cholewinski) conducted a site visit of the subject levee segments on November 13, 2024. On the morning of November 13th, the GEI ULDC Geotechnical Findings Report
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team started the site visit at the north end of the subject levees and walked south along each stretch of the subject levee, generally driving between the segments.

1.8.1. Objectives
The main objectives of the levee walk were the following:
⚫ Observe the current condition of the levee and visible surface facilities. ⚫ Identify apparent deficiencies that could affect levee compliance with ULDC criteria or require further assessment. Examples of potential levee deficiencies would include the following:
o Signs of slope instability such as slides, sloughs, tension cracking, slope depressions or bulges.
o Signs of settlement or unusual depressions in the levee crown. o Significant longitudinal or transverse cracks that could indicate possible movement or instability of the levee embankment.
o Signs of landside boils or soil transport that could indicate a history of unrepaired or undocumented seepage and piping.

1.8.2. Observations
The GEI team observed the current condition of the levee and visible surface facilities. Based on visual observations made during the visit, no evidence was found during the site visit of visible deficiencies that could affect levee compliance with the ULDC criteria covered by this report (Slope Stability, Underseepage, Levee Geometry, and Interfaces and Transitions).

1.9. Past Performance
The available past performance records of the subject SREL segments were collected, reviewed, and documented through 2017 in the reference documents cited in Section 1.5.

For this ULDC compliance assessment effort, GEI completed a due diligence effort to collect available past performance records for subject SREL levees for the period between 2017 and 2024. Between October and December 2024, GEI communicated with the LMA’s (City of Sacramento and DWR’s MA 9), USACE, SAFCA, DWR, and the Central Valley Flood Protection Board (CVFPB) to request available records or information. Information received included, but was not limited to, high water patrol records, fall and spring LMA levee inspection records, City of Sacramento Department of Utilities Levee Conditions forms, draft USACE O&M updates, and the 2021 USACE periodic inspection report. Received information was reviewed for performance records within the subject levee segments that could be of significance for ULDC compliance with respect to criteria evaluated in this report (i.e., seepage and stability). No performance records of significance were identified. The majority of records in the received information did not pertain to geotechnical considerations and criteria evaluated in this report and included primarily erosion and operation and maintenance items (e.g., vegetation conditions).

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2. ULDC Geotechnical Criteria Review
GEI’s geotechnical review involved examining the site investigations, engineering analyses, construction records, and other information contained in the reports cited in Section 1.5. The review was performed to determine whether the subject SREL segments meet the ULDC from a geotechnical perspective for the following sections:
⚫ 7.3 Soil Sampling, Testing, and Logging
⚫ 7.4 Slope Stability
⚫ 7.5 Underseepage
⚫ 7.8 Levee Geometry
⚫ 7.9 Interfaces and Transitions
The evaluation included a review of existing information referenced in this report and did not include performance of new analysis or field investigation. Where available, construction inspection records have also been reviewed.

The following sections of this report contain a summary of GEI’s evaluation.

2.1. ULDC Section 7.3 – Soil Sampling, Testing, and Logging This section contains a summary of the review of existing information for SREL Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00 with regards to ULDC Section 7.3: Soil Sampling, Testing, and Logging.

2.1.1. ULDC Requirements
The general requirements of this ULDC section are outlined below.

ULDC (DWR, 2012) Section 7.3 requires soil sampling, testing, and logging per standard procedures prescribed in guidance documents, including the USACE Sacramento District’s Geotechnical Levee Practice Standard Operating Procedure (SPK SOP) (USACE, 2022) and DWR’s Division of Flood Management Soil and Rock Logging, Classification, Description and Presentation Manual (2009). This includes an evaluation of soil exploration quantity and location as outlined in the SPK SOP (USACE, 2022).

Based on this document, explorations for a feasibility levee evaluation should be obtained at a spacing of approximately 1,000 feet along the levee crest and at a spacing of approximately 500 feet along the waterside toe, levee crown, landside toe for preconstruction and design studies. A spacing of approximately 500 feet for levee design equates to approximately 11 explorations each for the waterside toe, levee crown, and landside toe or about 33 total explorations per mile of levee. The SPK SOP denotes “waterside borings may be omitted if site conditions prevent access, such as waterside channels immediately adjacent to the levee, and these explorations may be shifted to the landside.” ULDC Geotechnical Findings Report
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The SPK SOP indicates that primary exploration depths should be a minimum of 4 times the levee height into the levee foundation or to the bottom of any aquifer that may be influencing levee performance.

Additionally explorations should extend to an appropriate stratum to evaluate stability and settlement.

The SPK SOP (USACE, 2022) also outlines explorations should have sampling and in-situ testing at frequencies necessary to obtain the engineering characteristics of the levee and foundation soil layers.

The SPK SOP (USACE, 2022) recommends a thorough evaluation of existing information as part of a levee evaluation program. This includes a review of original construction (if available), improvements, performance history, existing subsurface information, and regional and local geomorphology. The standard also recommends the use of cone penetrometers (CPTs) and geophysics to supplement explorations, where appropriate.

In addition, where available, the as-built plans, conformance laboratory tests, and in-place compaction tests for the construction and improvements of each levee were reviewed as part of the ULDC evaluation. This information was used to evaluate the levee geometry and material properties within the improved levee sections.

2.1.2. Evaluation
The SREL levee system has been extensively explored for geotechnical information. Subsurface conditions in the subject SREL segments can be interpreted from numerous subsurface explorations (completed between 1961 and 2020), geophysical surveys, and geomorphic studies. The details and results of the previous explorations are compiled and documented across several reports:
⚫ Kleinfelder, Inc., 2013a. “Geotechnical Data Report, Sacramento River East Levee Downstream of American River, SAFCA FEMA Levee Accreditation (North Area Streams, American River, Sacramento River Downstream of American River, and Beach Lake Levee), Sacramento County, California.” June.

Including as appendices:
o URS, 2008. “Phase 1 Geotechnical Data Report (P1GDR), Sacramento River Study Area, Urban Levee Geotechnical Evaluations Program, Contract 4600007418.” November. o URS, 2011. “Supplemental Geotechnical Data Report (SGDR), Sacramento River Study Area, Urban Levee Geotechnical Evaluations Program, Contract 4600007418.” September. ⚫ URS, 2014a. “Supplemental Geotechnical Data Report Addendum, Sacramento River Study Area, Urban Levee Evaluations Project, Contract 4600008101.” April. ⚫ GEI/HDR 2015a. “Supplemental Geotechnical Data Memorandum, Sacramento River East Levee Improvement Project, Revision 1.” October.
⚫ GEI/HDR, 2019b. “Addendum 1 to Supplemental Geotechnical Data Memorandum, Sacramento River East Levee.” August.
⚫ GEI/HDR, 2019d. “Addendum 2 to Supplemental Geotechnical Data Memorandum, Sacramento River East Levee.” December.

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⚫ Kleinfelder, Inc., 2020a. “Geotechnical Data Report, Geotechnical Characterization of Levee Material, Sacramento River East Levee – Stations 1104+00 to 1116+15, Sacramento, California.” September 2.
⚫ GEI/HDR, 2021a. “Addendum 3 to Supplemental Geotechnical Data Memorandum, Sacramento River East Levee.” January.

Appendix B of this report provides tables summarizing the available existing exploration records for each of the subject SREL Segments: Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00. Tables 2-1 through 2-4, below, summarize the number of explorations performed for each levee location including which of those meet the exploration depth requirement described in SPK SOP.

It can be noted that along the SREL, the placement of explorations waterside of the levee was generally impractical due to lack of a waterside berm, dense woody vegetation, and other access limitations. In these levee extents, the Sacramento River is generally adjacent to the levee. Consequently, the need for waterside characterization is greatly reduced since direct communication from the river to the aquifer is assumed either through exposure of the aquifer within the river channel or truncation of the waterside blanket.

Table 2-1. Summary of Exploration Counts for SREL Station 1080+00 to 1150+00 (1.33 Miles) Exploration Location
Number of Explorations
All Explorations
Explorations Meeting
SPK SOP 2022
Minimum Depth1
River Channel 7 2
Waterside Toe 0 0
Levee Crown 43 27
Landside Toe 15 8
Landside Field 2 112 21
Total 177 58
Average per Mile 133 44
Notes:

1. Based on SPK SOP consideration for primary explorations to extend to a depth of at least four times the levee height into the levee foundation.

2. Explorations greater than 500 feet offset from the levee stationing alignment were not included in the count.

Average exploration spacing for the SREL segment from Station 1080+00 to 1150+00 (not including explorations greater than 500 feet offset from the levee stationing alignment) is 54 feet with a maximum spacing of 406 feet. The average spacing for explorations along the levee crown of this SREL segment is 155 feet. With a segment length of about 1.33 miles, there is an average of about 32 explorations per mile along the levee crown, 19 explorations per mile at the landside levee toe, and 84 explorations per mile in the landside field.

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Table 2-2. Summary of Exploration Counts for SREL Station 1185+00 to 1206+00 (0.40 miles) Exploration Location
Number of Explorations
All Explorations
Explorations Meeting
SPK SOP 2022
Minimum Depth1
Waterside Toe 0 0
Levee Crown 15 7
Landside Toe 5 1
Landside Field2 10 4
Total 30 12
Average per Mile 75 30
Notes:

1. Based on SPK SOP consideration for primary explorations to extend to a depth of at least four times the levee height into the levee foundation or to the bottom of any aquifer that may be influencing levee performance.

2. Explorations greater than 500 feet offset from the levee stationing alignment were not included in the count.

Average exploration spacing for the SREL segment from Station 1185+00 to 1206+00 (not including explorations greater than 500 feet offset from the levee stationing alignment) is 77 feet with a maximum spacing of 285 feet. The average spacing for explorations along the levee crown of this SREL segment is 144 feet. With a segment length of about 0.4 mile, there is an average of about 38 explorations per mile along the levee crown, 13 explorations per mile at the landside levee toe, and 25 explorations per mile in the landside field.

Table 2-3. Summary of Exploration Counts for SREL Station 1285+75 to 1418+00 (2.50 Miles) Exploration Location
Number of Explorations
All Explorations
Explorations Meeting
SPK SOP 2022
Minimum Depth1
River Channel 3 0
Waterside Toe 1 1
Levee Crown 94 65
Landside Toe 38 14
Landside Field2 27 14
Total 163 94
Average per Mile 65 38
Notes:

1. Based on SPK SOP consideration for primary explorations to extend to a depth of at least four times the levee height into the levee foundation.

2. Explorations greater than 500 feet offset from the levee stationing alignment were not included in the count.

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Average exploration spacing for the SREL segment from Station 1285+75 to 1418+00 (not including explorations greater than 500 feet offset from the levee stationing alignment) is 88 feet with a maximum spacing of 428 feet. The average spacing for explorations along the levee crown of this SREL segment is 145 feet. With a segment length of about 2.5 miles, there is an average of about 2 explorations per mile on the waterside, 38 explorations per mile along the levee crown, 15 explorations per mile at the landside levee toe, and 10 explorations per mile in the landside field.

Table 2-4. Summary of Exploration Counts for SREL Station 1534+40 to 1640+00 (2.00 Miles) Exploration Location
Number of Explorations
All Explorations
Explorations Meeting
SPK SOP 2022
Minimum Depth1
Waterside Toe 0 0
Levee Crown 60 44
Landside Toe 37 22
Landside Field2 13 5
Total 110 71
Average per Mile 55 36
Notes:

1. Based on SPK SOP consideration for primary explorations to extend to a depth of at least four times the levee height into the levee foundation.

2. Explorations greater than 500 feet offset from the levee stationing alignment were not included.

Average exploration spacing for the SREL segment from Station 1534+40 to 1640+00 (not including explorations greater than 500 feet offset from the levee stationing alignment) is 110 feet with a maximum spacing of 455 feet. The average spacing for explorations along the levee crown of this SREL segment is 190 feet. With a segment length of about 2.0 miles, there is an average of 30 explorations per mile along the levee crown, 19 explorations per mile at the landside levee toe, and 7 explorations per mile in the landside field.

Explorations were generally completed with standard penetration test (SPT) sampling, sonic coring, or CPT methods. For SPT borings, sampling intervals of every 2 ½ feet to every 5 feet were generally implemented, documenting blow counts and field soils descriptions. For exploration completed since 2008 (including URS, Kleinfelder, and GEI/HDR explorations), laboratory testing was performed on select samples generally consistent with DWR’s Division of Flood Management Soil and Rock Logging, Classification, Description and Presentation Manual (2009) such as sieve analysis, Atterberg limits, unit weight, water content, and strength testing.

As part of previous geotechnical evaluations of the SREL area, geologic and geomorphologic mapping was performed of the area. The ULE SGDR (URS, 2011) includes documentation of the helicopter-borne electromagnetic (HEM) geophysical survey and geomorphic study completed. Based on the geomorphic information, the near-surface formations within the Project area are the Holocene alluvial deposits, Modesto Formation, and Riverbank Formation (GEI, 2020). The Holocene alluvial deposits consist of unconsolidated, loose, sand, silt and clay deposited by the Sacramento River during the last 11,000 years. These soils are underlain by Late Pleistocene sand, gravel, silt, and clay alluvial soils of the ULDC Geotechnical Findings Report
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Modesto Formation, typically unconsolidated and medium dense to very dense. The maximum thickness of Holocene and late Pleistocene Modesto Formation deposits is on the order of 100 to 120 feet. The Riverbank Formation underlies the Modesto Formation and is comprised of semi-consolidated to consolidated interbedded deposits of granitic sand, silt, and clay with lenses of metamorphic channel gravels. The deposits are laterally heterogeneous and vertically discontinuous, indicating that they were also deposited in a fluvial environment. The thickness of the Riverbank Formation is about 100 feet.

2.1.3. Conclusion
The intent of an exploration program for a levee evaluation project is to adequately characterize subsurface conditions such that the levee performance can be evaluated and improvements, if needed, can be designed, and constructed. Based on the information summarized in Section 2.2.2 and Appendix B, the subject SREL segments have more than 11 explorations per mile recommended by the USACE SPK SOP along the levee crown and along the landside levee toe. Along the SREL, the placement of explorations waterside of the levee was generally impractical, primarily because the Sacramento River is generally adjacent to the levee and also due to the lack of a waterside berm, the existence of dense woody vegetation along the river bank, and other access limitations. The USACE SPK SOP does acknowledge that waterside explorations may be omitted if site conditions prevent access, such as waterside channels immediately adjacent to the levee, and these explorations may be shifted to the landside. For SREL geotechnical analyses, the need for waterside characterization was greatly reduced because direct communication from the river to the aquifer was assumed, either through exposure of the aquifer within the river channel or truncation of the waterside blanket.

It is GEI’s professional opinion that the body of explorations and other subsurface information (including HEM data and geomorphic mapping) summarized above affords an understanding of levee and foundation conditions that meets or exceeds the standard of care implemented in similar levee remediation projects and is sufficient to support a finding of compliance with the ULDC Section 7.3 criteria for the subject segments of the SREL levee system.

2.2. ULDC Section 7.4 – Slope Stability for Intermittently Loaded Levees
This section provides a summary of the review of the existing geotechnical stability analyses performed for the subject SREL segments (Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00) as it applies to ULDC Section 7.4: Slope Stability for Intermittently Loaded Levees.

2.2.1. ULDC Requirements
ULDC defines an intermittently loaded levee as:
“Intermittently loaded levee means a levee that does not experience a water surface elevation of one foot or higher above the elevation of the levee toe at least once a day for more than 36 days per year on average.”
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The subject SREL levee is considered intermittently loaded because historical flood hydrographs confirm short-term peak flood flow events.

The general requirements of ULDC Section 7.4 Slope Stability for Intermittently Loaded Levees are outlined below. ULDC Section 7.4 requires slope stability analysis for the DWSE and at the HTOL WSE (if the HTOL is more than 0.5 foot above the DWSE).
“Engineers should use sound engineering judgment and guidance from EM 1110-2-1902 to decide what constitutes a minor, insignificant slip surface versus a sliding surface that threatens the integrity of the levee. These determinations should be based on performance history, levee geometry, type of levee fill material, stratigraphy of the levee embankment and foundation soils, seepage conditions (including pore water pressures calculated for the seepage analysis), soil strength characteristics, and potential for erosion. Those surfaces which significantly threaten the integrity of the levee must meet minimum slope stability criteria.” Steady-state landside stability and rapid drawdown waterside stability should be evaluated using the minimum factors of safety summarized in Table 2-5.

Table 2-5. Minimum ULDC Factors of Safety for Slope Stability Stability Analysis ULDC Minimum Factor of Safety1
Steady-State DWSE, Landside Slope 1.4
Steady-State HTOL WSE, Landside Slope 1.2
Rapid Drawdown DWSE, Waterside Slope 1.0-1.22
Notes:

1. Critical failure surface should intersect the levee crown and be greater than a few feet deep into the level slope.

2. Minimum factor of safety dependent on time extent DWSE may have saturated the waterside levee slope.

ULDC Section 7.4 also requires consideration for through seepage, stating:
“If the phreatic surface corresponding to the DWSE or HTOL emerges on a landside levee slope consisting of erodible soils, then remediation will be required to prevent unraveling and progressive slope failure that may lead to a levee breach.”

2.2.2. Evaluation
Results of previously performed slope stability analyses are summarized in a table presented in Appendix C. The table provides the analysis results, the analysis WSEs, and the current 2024 WSEs for each summarized analysis cross section. Detailed discussions of the slope stability analyses including cross section selection, technical approach, and parameters are included in the reports cited in the table.

The available analyses results were considered in light of the differences between the analysis WSEs and the current 2024 200-year and HTOL WSEs (Appendix A). In all cases the previously performed analyses were analyzed with 200-year and HTOL WSEs that were higher than the current 2024 200-year and HTOL WSEs and met slope stability criteria. Since soil and geometry conditions have not materially changed, ULDC Geotechnical Findings Report
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the previously performed slope stability analyses are considered to meet criteria for the current, lower WSEs.

2.2.3. Conclusion
Based on the information summarized in Section 2.2.2 and Appendix C the following conclusions can be made:
⚫ Analysis cross sections adequately model slope stability at critical locations along SREL (Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00).
⚫ The 2024 200-year and HTOL WSEs are lower than the WSEs modeled in the existing analyses. ⚫ The modeled improvements at the analysis cross sections were the same or less conservative than constructed improvements and met criteria at the analyzed locations.

Based on this review, it is GEI’s professional opinion that the subject SREL segments (Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00) meet the requirements of ULDC Section 7.4: Slope Stability for Intermittently Loaded Levees.

2.3. ULDC Section 7.5 – Underseepage for Intermittently Loaded Levees
This section provides a summary of the review of the existing underseepage analyses performed for the subject SREL segments (Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00) as it applies to ULDC Section 7.5: Underseepage for Intermittently Loaded Levees.

2.3.1. ULDC Requirements
As discussed in Section 2.2.1, the subject SREL levees are considered intermittently loaded. The general requirements of ULDC Section 7.5: Underseepage for Intermittently Loaded Levees, are outlined below.

ULDC Section 7.5 requires seepage analysis be performed for the DWSE and HTOL WSE (if the HTOL is more than 0.5 foot above the DWSE). Exit gradients are to be measured at the landside levee toe, seepage berm toe, ditches, canals, depressions, or areas of thin blanket. The allowable maximum exit gradient is summarized in the table below.

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Table 2-6. ULDC Allowable Underseepage Exist Gradients
Seepage Analysis Location Allowable Maximum Exit
Gradient1
Steady-State DWSE
Landside Levee Toe 0.5 2
Ditches, canals, depressions,
berms

0.5-0.8 2,3
Steady-State HTOL WSE
Landside Levee Toe 0.6 4
Ditches, canals, depressions,
berms

0.6-0.9 2,3,4
Notes:

1. The saturated unit weights of the “in-situ” landside blanket soils must be at or above 112 pounds per cubic foot in order to use these exit gradient criteria shown. If soils weigh less than 112 pcf, the minimum Factor of Safety criteria provided separately in ULDC Section 7.5 is to be followed.

2. The allowable underseepage exit gradient through the combined seepage berm/blanket layer between the levee toe and the seepage berm toe for a water surface set at the DWSE is determined by interpolation, using 0.5 at the levee toe and 0.8 at the seepage berm toe.

3. Maximum allowable exit gradient at the landside levee toe is 0.5 and up to 0.8 at 150 feet from the levee toe, using linear interpolation for distances in between. ULDC does allow for higher exit gradients at the seepage berm toe provided sound engineer judgement, and additional analysis. For the HTOL, “In general if the berm is less than 100-ft wide, the maximum exit gradient may increase by up to 20 percent of the DWSE maximum exit gradient”

4. For the HTOL, the maximum allowable exit gradient in the ditch, canal, or depression is 0.6 at the levee toe and gradients beyond the toe are allowed up to 20 percent higher than the maximum allowable exit gradients specified above for the DWSE for the same distance from the levee toe.

2.3.2. Evaluation
Results of previously performed seepage analyses are summarized in in a table presented in Appendix C.

The table provides the analysis results, the analysis WSEs, and the current 2024 WSEs for each summarized analysis cross section. Detailed discussions of the seepage analyses including cross section selection, technical approach, and parameters are included in the reports cited in the table.

The available analyses results were considered in light of the differences between the analysis WSEs and the current 2024 200-year and HTOL WSEs (Appendix A). In all cases the previously performed analyses were analyzed with 200-year and HTOL WSEs that were higher than the current 2024 200-year and HTOL WSEs and met underseepage criteria. Since soil and geometry conditions have not materially changed, the previously performed seepage analyses are considered to meet criteria for the current, lower WSEs.

Swimming pools near the levee toe present potential seepage considerations because installation of the swimming pool into the blanket may have thinned the blanket. GEI previously completed a screening assessment of potential excessive underseepage exit gradients and/or potential uplift during design highwater events for 78 existing swimming pools within the SREL system (Appendix E1 of GEI, 2020). Based on this assessment, it was recommended that the pools near the levee toe be maintained full of water during high river stages to help protect the integrity of the levee structure. A recommendation for keeping the pools full during the flood season should be considered for incorporation in the LMA’s respective O&M manuals for the levee and in the instructions given to levee patrols during high water stages. Public outreach by/with the LMAs was suggested to inform the landowners and encourage them to implement the recommendation.

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It is noted that in a 2017 conversation between GEI’s Alberto Pujol and DWR’s Al Romero (MA 9 maintenance supervisor, retired), Mr. Romero indicated that in his recollection MA 9 had never observed seepage issues (boils or excessive seepage) concentrated at or around swimming pools.

2.3.3. Conclusion
Based on the information summarized in Section 2.3.2 and Appendix C the following conclusions can be made:
⚫ Analysis cross sections adequately model underseepage at critical locations along subject SREL segments (Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00).
⚫ The 2024 200-year and HTOL WSEs are lower than the WSEs modeled in the existing analyses. ⚫ The modeled improvements were the same or less conservative than the constructed improvement and met criteria at the analyzed locations.

Based on the above review, it is GEI’s professional opinion that the subject SREL segments (Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00) meet the requirements of ULDC Section 7.5: Underseepage for Intermittently Loaded Levees.

2.4. ULDC Section 7.8 – Levee Geometry
This section provides a summary of the geometry assessment performed for the subject SREL segments (Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00) as it applies to ULDC Section 7.8: Levee Geometry.

2.4.1. ULDC Requirements
The ULDC Section 7.8, Levee Geometry, is as follows.
“Minimum levee geometry criteria have previously been specified by various USACE and State guidance documents. The guidance for various minimum levee geometry and their references are as follows in Table 7-1.”
ULDC Table 7-1 is reproduced below as Table 2-7.

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Table 2-7. Reproduction of ULDC Table 7-1 – Summary of Existing Levee Geometry Guidance USACE Engineering
Manual EM 1110-2-
1913 (April 30, 2000)
Title 23. Waters Division

1. Central Valley Flood
Protection Board
California Code of
Regulations
(January 22, 2010)
USACE Sacramento
District Geotechnical
Levee Practice SOP
(April 11, 2008)
Minimum Crown Width
(feet) 10
20 (major stream levees)
12 (minor stream levees)
20 (main line, major
tributary,
and bypass levees)
12 (minor tributary levees)
Minimum Waterside
Levee Slope 2h:1v
3h:1v
4h:1v
(bypass levees)
3h:1v
Minimum Landside
Levee Slope 2h:1v
3h:1v
4h:1v
(bypass levees)
3h:1v
(new levees)
2h:1v
(existing levees with
good
performance)
Section 7.8 of ULDC clarifies and refines the geometry guidelines as follows:
“For new levees, or levees with extensive reconstruction, situated along major waterways, a minimum 20-foot-wide crown width and 3h:1v waterside and landside slopes (4h:1v waterside slope for bypass levees) is required. Exceptions may be allowed for reconstruction of existing levees where the authorized geometry provides for a steeper slope or narrower crown, the levee has performed well, and it meets stability and seepage criteria. These geometry requirements represent minimum requirements, and wider levee crowns and/or flatter slopes may be necessary in some areas, depending upon geologic and geotechnical considerations. At the same time, however, minimum requirements should be associated with generally uniform, levee materials and homogeneous embankments. Steeper slopes may be allowed in certain circumstances where there is limited space available, and where levees are demonstrated to meet minimum seepage and stability criteria. Steeper waterside levee slopes may be acceptable where stability criteria are met and either slope protection is provided or it is determined that wavewash erosion for a water surface at or below the DWSE could not result in breaching of the levee. For example, levees with slopes steeper than new minimum requirements may be acceptable with elements such as central clay cores, seepage cutoff walls, landside filters or drains, or soil reinforcement that substantially decrease seepage hazards and increase slope stability.”
“The levee prism should be considered to continue underground based on projection of the above-ground levee slopes. The projected levee slopes are useful for evaluating erosion, excavations, and encroachments near the levee.”
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ULDC also provides consideration for wide levees in Section 7.8 including:
“Levees that are wider than the minimum requirement may have steeper slopes if the minimum required dimensions would fit entirely within the actual levee, and if seepage and slope stability criteria are met (for both deep and shallow failure surfaces).” The Sacramento River is considered a major stream and the SREL is a main line levee.

2.4.2. Evaluation
Psomas obtained representative levee cross sections (Psomas, 2024) to evaluate the existing geometry and 2024 DWSEs with the ULDC criteria. Cross section graphics for subject SREL segments prepared by MBK are included in Appendix D. Each section shows two profiles, the required ULDC geometry and the surveyed cross section. The crest elevation for the required geometry section is the DWSE plus three feet for minimum freeboard (i.e., the minimum top of levee [MTOL]); the centerline is the historic centerline.

The cross sections in Appendix D illustrate that the levee dimensions typically exceed the minimum requirements, particularly with respect to height (freeboard) and crown width. The required levee geometry fits completely within the 2024 surveyed existing levee embankment prisms. The landside slope is generally steeper than specified for homogeneous levees in ULDC Table 7-1. The waterside slope is often also steeper than specified in ULDC Table 7-1 for homogeneous levees. However, the SREL is not a homogeneous levee.

As summarized in Table 1-1 in Section 1.3, the subject SREL segments typically include one, and more commonly two, cutoff walls, with the newer wall installed to a greater depth than the older one. In the northernmost segment, the levee is typically overbuilt to accommodate railroad tracks and thus has a crown width of two or three times greater than specified for main line levees. In addition, the portions of the levee without cutoff wall typically include a landside berm with or without drainage elements, a seepage berm, or a relief well system.

As described in the previous subsections, the four levee segments evaluated meet minimum seepage and stability criteria. The levee is typically wider than the minimum requirement and, according to Section 7.8 of the ULDC, it may have steeper slopes if the minimum required dimensions would fit entirely within the actual levee and if seepage and slope stability criteria are met. Additionally, the levee typically includes protective measures to decrease seepage hazards and increase slope stability such as one or two seepage cutoff walls, landside berms, and relief wells. According to Section 7.8 of the ULDC, the levee may be considered to be acceptable with steeper slopes based on these considerations.

In a few small localized areas the waterside slope of the theoretical levee prism, projected below the levee embankment, extends beyond the surveyed riverbank slope. This is observed in the Appendix D sections at Stations 1386+50, 1574+30, and 1599+10. However, stability and seepage analyses continue to meet criteria in these levee reaches. Additionally, these localized erosion areas are being addressed within the USACE-led erosion protection projects that are currently being implemented. Specifically, SREL Erosion Contract 3 includes Station 1386+50 in its Site 7 design and Stations 1574+30 and 1599+10 in its Site 9 design. Construction of SREL Erosion Contact 3 is expected to be completed in 2025 and 2026.

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2.4.3. Conclusion
Based upon the above data, GEI makes the following conclusion:
⚫ The required levee geometry fits completely within the 2024 surveyed existing levee embankment prisms for the subject SREL Segments (Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00). ⚫ The subject levee segments are not a homogeneous levee, since they typically include cutoff walls, landside berms, or a relief well system. These protective features substantially decrease seepage hazards and increase slope stability.
⚫ The four levee segments evaluated meet minimum seepage and stability criteria.

From a geotechnical perspective, the above information is considered applicable and appropriate to provide an adequate assessment of levee geometry regarding the guidance outlined above for ULDC Section 7.8 Levee Geometry. Based on the reference analyses, the record drawings for levee modifications, and the recent Psomas cross section surveys, it is GEI’s professional opinion that the evaluated SREL segments meet the requirements for ULDC Section 7.8, Levee Geometry.

2.5. ULDC Section 7.9 – Interfaces and Transitions
This section contains a summary of the review of existing information for the subject SREL segments (Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00) with regards to ULDC Section 7.9: Interfaces and Transitions.

2.5.1. ULDC Requirements
ULDC Section 7.9: Interfaces and Transitions, contains the following requirements:
“The civil engineer must consider, evaluate, and explicitly design for interfaces and transitions between different types of levee sections and features along a levee system. Appropriate overlaps, transitions, and connections between features must be evaluated and designed to ensure that the levee system functions holistically, such that no levee reach is more susceptible to problems than an adjacent reach due to gaps in features, loading/demand concentrations, or other three- dimensional effects. Such interfaces, transitions, and connections commonly occur at the ends of seepage berms, seepage cutoff walls, revetments, and floodwalls.”

2.5.2. Existing Transitions
The SREL in the subject segments (Station 1080+00 to 1150+00, Station 1185+00 to 1206+00, Station 1285+75 to 1418+00, and Station 1534+40 to 1640+00) is composed of an earthen embankment. The known construction history is summarized in Section 1.3. Improvements to the levee have been constructed since the 1990s. Table 1-1 in Section 1.3 summarizes the extents of the constructed seepage and stability improvements within the subject SREL segments.

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Design for improvements constructed between 2019 and 2021 included consideration of transitions to provide appropriate overlaps or extensions of improvements. End-around seepage was considered at the terminus points of a cutoff wall where the aquifer layers continue upstream and/or downstream of a levee section improved with the cutoff wall and may impact its effectiveness. Where potential for endaround seepage was identified, evaluations were performed to determine that the proposed length of improvement measures were adequate to account for end-around seepage conditions. Considerations and evaluation were presented in the Design Documentation Reports (GEI, 2019a; GEI, 2019c; and GEI, 2020).

Transitions and interfaces along subject SREL segments are discussed below.

2.5.2.1. Transitions within SREL from Station 1080+00 to 1150+00 The drained stability berm constructed in 2019 from Station 1086+18 to 1090+33 is bordered on both sides by reaches that were evaluated to meet geotechnical criteria without improvements.

The jet grout cutoff wall constructed from Station 1093+50 to 1098+50 was extended beyond the geotechnical analysis reach (Reach 4-1) limits of Station 1094+50 to 1096+75 to sufficiently reduce the exit gradients caused by underseepage around the ends of the wall. At the southern end, the jet grout cutoff wall also overlaps the drained stability berm remediation that begins at Station 1096+91 by about 150 feet. A drained seepage berm and relief wells installed in 2006 (4 of which were modified in 2021), are also present between Station 1095+54 and 1102+07.

The drained stability berm has a downstream limit of Station 1102+21. It ends at a larger earth section that is present beneath the Highway 50 viaduct and where no levee improvements were judged to be required. South of the Highway 50 viaduct a jet grout wall was constructed beginning at Station 1105+00, still in the larger earth section referred to above. The jet grout cutoff wall extends to Station 1112+40 into a large embankment that forms the Broadway crossing with the levee. The wall was judged not to be required between Stations 1112+40 and 1114+00 due to the presence of high ground forming the Broadway crossing with the levee. An end-around analysis was performed to check that the levee at this cutoff wall gap meets underseepage and stability criteria for existing conditions.

The jet grout wall restarts at Station 1114+00 and a 15-foot overlap is provided between Station 1116+00 and 1116+15 where the 2021 jet grout cutoff wall ties into the 2020 SCCB cutoff wall.

The SCCB cutoff wall ends at Station 1125+50, where it overlaps with a shallow SCB cutoff wall constructed by the USACE between 1991 and 1993, which begins at approximately Station 1125+00. At the south end of the wall a seepage berm was constructed between Station 1124+95 and 1130+17 to address a low area landward of the levee. The berm filled the low area, tying into higher ground provided by Front Street and parking area embankment and the Interstate 5 embankment, addressing the concern of adverse 3D seepage effects around the downstream end of the SCCB cutoff wall into the previously low area landward of the levee. This seepage berm overlaps on the upstream end with the SCCB cutoff wall between Stations 1124+95 and 1125+50. Beyond the downstream limit of the seepage berm, evaluation indicated the existing levee met geotechnical criteria without further improvements subsequent to the 1990s USACE wall construction.

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2.5.2.2. Transitions within SREL from Station 1185+00 to 1206+00 A shallow SCB cutoff wall constructed between 1991 and 1993 is present through the full extents of this SREL segment. A deeper SB wall was constructed in 2020 from Station 1199+00 to Station 1207+75 to address an area of lower ground where Interstate 5 crosses the railroad track.

Upstream of Station 1199+00 the levee was evaluated to meet geotechnical criteria without further improvements subsequent to the 1990s USACE wall construction.

The geotechnical analysis reach (Reach 9) that identified the need for the 2021 cutoff wall had a downstream limit of Station 1206+00. However, the cutoff wall was extended beyond the reach boundary, to Station 1207+75, to address end-around effects and reduce the likelihood of backward erosion piping to progress around the cutoff wall. The length of additional wall was calculated to provide sufficient distance to dissipate pore pressures in the aquifer to acceptable values meeting ULDC underseepage criteria.

2.5.2.3. Transitions within SREL from Station 1285+75 to 1418+00 Shallow cutoff walls constructed by the USACE in the 1990s are present through the full extents of this SREL segment. In 2003 SAFCA constructed a deep wall between Station 1261+53 and Station 1285+50, and in 2006 USACE constructed a deep wall between Stations 1406+99 and 1424+51. These DMM walls formed the upstream and downstream limits of this segment. Additional cutoff walls (DMM, SB and SCCB) were constructed in 2020 and 2021 from Station 1282+90 to 1310+00 and Station 1336+00 to 1407+50.

The geotechnical analysis reach (Reach 12) that identified the need for the 2021 DMM cutoff wall has an upstream limit of Station 1285+75. The cutoff wall was extended upstream (north) to Station 1282+90, to overlap 260 feet with the DMM cutoff wall previously installed by SAFCA in 2003. The relatively-long overlap was identified to reduce the potential for preferential seepage flow paths to develop beneath the downstream end of the 2003 DMM wall, as it was questionable whether the downstream end of the 2003 DMM wall affirmatively keyed into an aquiclude.

Between Station 1300+30 and 1300+80 a 50-foot overlap is provided between the DMM wall constructed in 2020 and the SB wall constructed in 2021.

The levee from Station 1310+00 to Station 1336+00 was evaluated to meet geotechnical criteria without further improvements subsequent to the 1990s USACE wall construction. A new SB cutoff wall was installed by the USACE in 2021 beginning at Station 1336+00. The downstream end of the 2021 SCCB cutoff wall was extended to Station 1407+50 to provide an approximately 50 foot overlap with the 2006 USACE deep cutoff wall to account for seepage around the end of the 2006 deep wall.

2.5.2.4. Transitions within SREL from Station 1534+40 to 1640+00 Cutoff walls have been constructed throughout the extents of this southernmost subject SREL segment from Station 1534+00 to Station 1640+00, including a continuous shallow wall by the USACE in the 1990s and a continuous deeper wall installed by the USACE in 2020 using DMM, SB and SCCB methods. A 30- foot overlap was typically provided for transitions between the different wall types constructed in 2020.

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At the upstream limit of this segment, the DMM cutoff wall constructed in 2020 was installed with an approximately 35 foot overlap with a DMM cutoff wall and area of relief wells constructed by SAFCA at Sump 132 in 2003.

The downstream limit segment at Station 1640+00 corresponds with the end of the cutoff wall constructed in 2020 to an elevation of -55. This end location is over 500 feet beyond the locations of observed seepage reported within the reach after the construction of the 1991-93 USACE shallow cutoff.

The 1991-93 USACE shallow cutoff continues downstream of Station 1640+00 to approximately Station 1756+03.

2.5.3. Conclusion
Based upon the above information and the supporting analyses in the reference documents, it is GEI’s opinion that the above interfaces and transitions meet the geotechnical requirements of ULDC (DWR, 2012) Section 7.9: Interfaces and Transitions.

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3. Summary of Results
Based on the review summarized in Section 2 above, Table 3-1 summarizes GEI’s conclusions regarding levee compliance with geotechnical aspects of the ULDC (DWR, 2012) for Sections 7.3 Soil Sampling, Testing, and Logging, 7.4 Slope Stability, 7.5 Underseepage, and 7.9 Interfaces and Transitions.

Table 3-1. Levee Segments that Meet Geotechnical Aspects of ULDC Criteria Levee Approximate Levee
Stationing
Meets
Criteria
Does Not
Meet ULDC Criteria Section
Sacramento River
East Levee 1080+00 to 1150+00 X

7.3 Soil Sampling, Testing, and Logging

7.4 Slope Stability

7.5 Underseepage

7.8 Levee Geometry

7.9 Interfaces and Transitions
Sacramento River
East Levee 1185+00 to 1206+00 X

7.3 Soil Sampling, Testing, and Logging

7.4 Slope Stability

7.5 Underseepage

7.8 Levee Geometry

7.9 Interfaces and Transitions
Sacramento River
East Levee 1285+75 to 1418+00 X

7.3 Soil Sampling, Testing, and Logging

7.4 Slope Stability

7.5 Underseepage

7.8 Levee Geometry

7.9 Interfaces and Transitions
Sacramento River
East Levee 1534+40 to 1640+00 X

7.3 Soil Sampling, Testing, and Logging

7.4 Slope Stability

7.5 Underseepage

7.8 Levee Geometry

7.9 Interfaces and Transitions
It is GEI’s opinion that the levee segments of the SREL specified above meet the geotechnical-related requirements of the ULDC Sections outlined in Table 3-1 above.

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4. Limitations
Our professional services are limited to support Engineer’s Opinions for ULDC criteria that address soil sampling testing and logging, levee slope stability (including through seepage), underseepage, levee geometry, and interfaces and transitions for GEI’s assigned levee segments. The professional opinions contained in this ULDC Geotechnical Findings Report do not constitute a warranty or guarantee of performance, expressed or implied. The term “certification” is not intended to provide a guarantee or warranty of the conditions of the levee or its performance. GEI’s conclusions regarding the condition and safety of the levee segments and related facilities and their conformance to ULDC are not guaranteed, but do represent our best judgment. Inevitably, such judgment must be recognized to be affected to an uncertain degree by the practical limitations which affect all evaluations of constructed water-retention structures, relative principally to approximate knowledge of the condition and properties of the foundation materials and existing structures.

The conclusions in this ULDC Geotechnical Findings Report are based in part upon the data obtained from limited correspondence, reports, surveys, instrumentation monitoring programs, testing and surface observations. Actual conditions may escape detection by the reporting, surveying, monitoring, testing and observation techniques used and may therefore be different from those described. The nature and extent of such variations may not become evident until the levees experience high water conditions during future flood events, or when further tests and evaluations are performed. If variations from the described conditions are encountered, additional investigations and assessments of the levee condition and performance may need to be conducted. It may be necessary to revise the conclusions and recommendations described herein, and/or undertake additional remediation measures. If conditions are encountered that differ from those described herein, the client is responsible for ensuring that GEI is notified immediately so that we may reevaluate the conclusions of this report.

The accuracy, completeness, or reliability of data collected by third parties and referenced in this report and supporting reference documents, including, but not limited to, geotechnical explorations and subsurface data, is not attested by GEI. In the creation of this report, reliance is placed on data and information provided by external sources, without the ability for independent validation or verification.

Our services were performed in a manner consistent with the degree of skill and care ordinarily exercised by members of the profession currently practicing in the same locality under similar conditions. No other warranty, express or implied, is made.

This Geotechnical Findings Report is intended for the use and benefit of SAFCA or its designated representatives only. Any use by other parties is at their own discretion and risk.

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5. References
Department of Water Resources, California, 2012. “Urban Levee Design Criteria, State of California, Department of Water Resources.” May.

Department of Water Resources, California, 2015. “Guidance Document for Geotechnical Analyses, Urban Levee Geotechnical Evaluations Program.” April 27.

GEI/HDR 2015a. “Supplemental Geotechnical Data Memorandum, Sacramento River East Levee Improvement Project, Revision 1.” October.

GEI/HDR, 2015b. “Alternatives Evaluation Memorandum, Sacramento River East Levee Improvement Project.” December 28.

GEI/HDR, 2016. “Embankment and Foundation Stability Memorandum, Sacramento River East Levee Improvement Project, Revision 1.” August.

GEI/HDR, 2017. Memorandum – “Levee Performance Reconnaissance, Sacramento River East Levee Improvement Project, Sacramento, California.” February 23.

GEI/HDR, 2018. “Draft Engineering Report, Sacramento River East Levee Improvement Project.” August.

GEI/HDR, 2019a. “Design Documentation Report, American River Common Features Project WRDA 2016, ARS Basin Reach D, Contract 1 Drained Stability Berm.” March.

GEI/HDR, 2019b. “Addendum 1 to Supplemental Geotechnical Data Memorandum, Sacramento River East Levee.” August.

GEI/HDR, 2019c. “Final Design Documentation Report, American River Common Features 2016 Sacramento River East Levee – Contract 1.” November.

GEI/HDR, 2019d. “Addendum 2 to Supplemental Geotechnical Data Memorandum, Sacramento River East Levee.” December.

GEI/HDR, 2020. “Final Design Documentation Report, American River Common Features 2016 Sacramento River East Levee – Contract 2.” October.

GEI/HDR, 2021a. “Addendum 3 to Supplemental Geotechnical Data Memorandum, Sacramento River East Levee.” January.

GEI/HDR, 2021b. “Construction Completion Report, American River Common Features Project WRDA 2016, ARS Basin Reach D, Contract 1 Drained Stability Berm.” July.

GEI/HDR, 2021c. “Construction Completion Report, American River Common Features 2016 Sacramento River East Levee – Contract 1.” July.

ULDC Geotechnical Findings Report
American River South Levee System – Sacramento River East Levee April 2025
GEI Consultants, Inc. 28
GEI/HDR, 2022. “Construction Completion Report, American River Common Features 2016 Sacramento River East Levee – Contract 2.” September.

Kleinfelder, Inc., 2013a. “Geotechnical Data Report, Sacramento River East Levee Downstream of American River, SAFCA FEMA Levee Accreditation (North Area Streams, American River, Sacramento River Downstream of American River, and Beach Lake Levee), Sacramento County, California.” June.

Kleinfelder, Inc., 2013b. “Problem Identification Report Sacramento River East Levee Downstream of American River, SAFCA FEMA Levee Accreditation (North Area Streams, American River, Sacramento River Downstream of American River, And Beach Lake Levee). Sacramento County, California.” August.

Kleinfelder, Inc., 2014. “ULDC Geotechnical Results Summary Report, Sacramento River East Levee Downstream of American River, SAFCA FEMA Levee Accreditation (North Area Streams, American River, Sacramento River Downstream of American River, And Beach Lake Levee). Sacramento County, California.” March.

Kleinfelder, Inc., 2020a. “Geotechnical Data Report, Geotechnical Characterization of Levee Material, Sacramento River East Levee – Stations 1104+00 to 1116+15, Sacramento, California.” September 2.

Kleinfelder, Inc., 2020b. “Environmental Field Exploration Summary Report, Characterization of Levee Material, Sacramento River East Levee – Stations 1093+50 to 1116+15, Sacramento, California.” October 2.

MBK, 2016. Technical Memorandum – “Determination of Design Water Surface Elevation for SAFCA Sacramento River East Levee Improvement Project.” September 14.

MBK, 2025. Technical Memorandum – “American River South Levee System – Determination of the Urban Levee Design Criteria Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee.” April 9.

State of California, 2009. “California Code of Regulations, Title 23, Water.” December.

URS, 2008. “Phase 1 Geotechnical Data Report (P1GDR), Sacramento River Study Area, Urban Levee Geotechnical Evaluations Program, Contract 4600007418.” November.

URS, 2011. “Supplemental Geotechnical Data Report (SGDR), Sacramento River Study Area, Urban Levee Geotechnical Evaluations Program, Contract 4600007418.” September.

URS, 2014a. “Supplemental Geotechnical Data Report Addendum, Sacramento River Study Area, Urban Levee Evaluations Project, Contract 4600008101.” April.

URS, 2014b. “Geotechnical Evaluation Report Volume 1, Existing Conditions, Sacramento River Study Area, Urban Levee Evaluations Project, Contract 4600008101.” July.

URS, 2015. “Geotechnical Evaluation Report Volume 2, Remedial Alternatives, Sacramento River Study Area, Urban Levee Evaluations Project, Contract 4600008101.” January.

ULDC Geotechnical Findings Report
American River South Levee System – Sacramento River East Levee April 2025
GEI Consultants, Inc. 29
USACE, 1993. “Sacramento Urban Area Levee Reconstruction Project, California. Greenhaven – Pocket, Phase 1 and Phase 2.” May 14.

USACE, 2013. “Geotechnical Office Report, American River Watershed Common Features Project General Reevaluation Report.” October.

USACE, 2015. “American River Watershed Common Features General Reevaluation Report.” December.

USACE, 2000. “U.S. Army Corps of Engineers, Engineer Manual, EM 1110-2-1913, Design and Construction of Levees.” April 30.

USACE, 2005. “U.S. Army Corps of Engineers, Technical Letter ETL 1110-2-569, Design Guidance for Levee Underseepage.” May 1.

USACE, 2022. “CESPK-EDG, SOP 3 Geotechnical Levee Practice, May 2022, Standard Operating Procedure 3, Geotechnical Levee Practice, U.S. Army Corps of Engineers, Sacramento District, Geotechnical Engineering Branch.” May.

U.S. Code of Federal Regulations Title 44 (44 CFR) Section 65.10: Mapping of Areas Protected by Levee Systems. October 1, 2017.

ULDC Geotechnical Findings Report
American River South Levee System – Sacramento River East Levee April 2025
GEI Consultants, Inc.

Figures
Figure 1 – ULDC Certification Levee Extents
Figure 2 – Reaches and Cross Sections (Sheet 1 of 4)
Figure 3 – Reaches and Cross Sections (Sheet 2 of 4)
Figure 4 – Reaches and Cross Sections (Sheet 3 of 4)
Figure 5 – Reaches and Cross Sections (Sheet 4 of 4)
1040+00
1080+00
1120+00
1160+00
1200+00
1240+00
1280+00
1320+00 1360+00
1400+00
1440+00
1480+00
1520+00
1560+00
1600+00
1640+00
1680+00
1720+00
1760+00
1000+00
1772+00
Station 1080+00 to Station 1150+00
Station 1185+00 to Station 1206+00
Station 1285+75 to Station 1418+00
Station 1534+40 to Station 1640+00
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·|þ}99
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·|þ}84
·|þ}160
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§¨¦80
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32nd St
S
River Rd
6th St
37th St
I St
Pine St
14th Ave
25th St
Blair Ave
P ortola Way
Enterprise Blvd
Havensi de Dr
Evergreen Ave
F St
Anna St
4th Ave
Mack
Rd
Capitol Mall
12th Ave
Kegle Dr
21st Ave
Riske Ln
15th St
C St
Westacre Rd
Riverbank Rd
Y St
14th St
Sacramento Ave
Stone Blvd
Stockton Blvd
Todhunter Ave
N Harbor Blvd
Windbridge Dr
L St
Sutterville Rd
7th
St
Park Blvd
Gregory Ave
43rdAve
Capitol Ave
Seamas Ave
47th Ave
3rd
St
35th Ave
30th
St
Davis Rd
E St
10th
St
9th
St
19th
St
Rush River Dr
29th St
Alhambra Blvd
Land
Park Dr
W St
Broadway
Meadowview Rd
X St
H St
5th
St
T St
P St
Q St
N St
Industrial Blvd
21st St
J St
24th
St
Fruitridge Rd
Martin Luther King Jr B
vl d
Gloria Dr
24th St
Linden Rd
Pocket Rd
S Land P a rk Dr
Riverside
Blvd
Riverside
Blvd
Franklin Blvd
Florin Rd
RichardsBlvd
Harbor Blvd
Greenhaven Dr
W Capitol Ave
Sacramento River East Levee
Sacramento, CA
Sacramento Area Flood Control Agency MARCH 2025 FIGURE 1

ULDC CERTIFICATION

LEVEE EXTENTS
05-Mar-2025 Z:\Projects\1804694_SAFCA\SREL_ULDC_Certification_LeveeExtents.mxd RS ± 4,000 2,000 0 4,000
Feet
Levee Extent Covered by GEI ULDC
Geotechnical Findings Report
Stationing Alignment
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1160+00
1200+00
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Sacramento River East Levee
Sacramento, CA
Sacramento Area Flood Control Agency MARCH 2025 FIGURE 2

REACHES AND CROSS SECTIONS
(SHEET 1 OF 4)
05-Mar-2025 Z:\Projects\1804694_SAFCA\SREL_ULDC_Certification_LeveeExtents_mapbook.mxd RS ® 1,000 500 0 1,000
Feet
? ?Cross Section
" " Reach
Stationing Alignment
Levee Extent Covered by GEI ULDC
Geotechnical Findings Report
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Reach 12
Reach
9 Reach 16
Reach 13
Reach
14 Reach 15
Sacramento River East Levee
Sacramento, CA
Sacramento Area Flood Control Agency MARCH 2025 FIGURE 3

REACHES AND CROSS SECTIONS
(SHEET 2 OF 4)
05-Mar-2025 Z:\Projects\1804694_SAFCA\SREL_ULDC_Certification_LeveeExtents_mapbook.mxd RS ® 1,000 500 0 1,000
Feet
? ?Cross Section
" " Reach
Stationing Alignment
Levee Extent Covered by GEI ULDC
Geotechnical Findings Report
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1400+00
1440+00
1480+00
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9 +
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1406+25
13 6
2 +
7 5
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5 +
0 0
13 6
7 +
2 5
Reach
19 Reac
25 h
Reach 18
Reach 15
Reach
24 Reach 17
Reach 16
Sacramento River East Levee
Sacramento, CA
Sacramento Area Flood Control Agency MARCH 2025 FIGURE 4

REACHES AND CROSS SECTIONS
(SHEET 3 OF 4)
05-Mar-2025 Z:\Projects\1804694_SAFCA\SREL_ULDC_Certification_LeveeExtents_mapbook.mxd RS ® 1,000 500 0 1,000
Feet
? ?Cross Section
" " Reach
Stationing Alignment
Levee Extent Covered by GEI ULDC
Geotechnical Findings Report
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1600+00
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1544+30
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16 2
7 +
5 0
§¨¦5
Reac
25 h
Reach
24 Reach 26
Reach 27
Sacramento River East Levee
Sacramento, CA
Sacramento Area Flood Control Agency MARCH 2025 FIGURE 5

REACHES AND CROSS SECTIONS
(SHEET 4 OF 4)
05-Mar-2025 Z:\Projects\1804694_SAFCA\SREL_ULDC_Certification_LeveeExtents_mapbook.mxd RS ® 1,000 500 0 1,000
Feet
? ?Cross Section
" " Reach
Stationing Alignment
Levee Extent Covered by GEI ULDC
Geotechnical Findings Report
ULDC Geotechnical Findings Report
American River South Levee System – Sacramento River East Levee April 2025
GEI Consultants, Inc.

Appendix A ULDC Water Surface Elevations
MBK Engineers, 2025. “Technical Memorandum: American River South Levee System - Determination of the Urban Levee Design Criteria Design Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee.” Dated April 9, 2025
Water Resources Flood Control Water Rights