Agenda packet, regular meeting — San Ramon City Council, February 25, 2025 (part 2 of 4)

5.6.b
Packet Pg. 209 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 137 six (6) utility systems (i.e., potable water, wastewater, natural gas, crude and refined oil, electric power and communications). Hazus estimates that the total value of the lifeline inventory (transportation and utility) is over $28.9 Million which includes 344.9 miles of highways, 613 bridges, and 9,751.2 miles of pipeline (potable water, wastewater, natural gas, and oil). Table 4-84 summarizes the expected damage to utility systems in Contra Costa County. All utility systems are expected to have functionality greater than 50% on day seven (7) after the earthquake event.

Table 4-84. Expected Damage to Utility Systems
System Total
Number of Locations
With at Least
Moderate Damage
With Complete
Damage
With Functionality
Greater than 50%
After Day 1 After Day 7
Potable Water 6 5 0 0 6
Wastewater 14 1 0 0 14
Natural Gas 0 0 0 0 0
Oil Systems 11 1 0 0 11
Electrical Power 22 13 0 11 22
Communication 9 2 0 9 9
For the transportation systems, HAZUS calculates the direct repair cost for each component only. Table 4-85 provides damage estimate for the transportation systems.

Table 4-85. Expected Damage to the Transportation Systems System Component
Number of Locations
Locations /
Segments
With at
Least
Moderate
Damage
With
Complete
Damage
With Functionality
Greater than 50%
After Day 1 After Day 7
Highway
Segments 408 0 0 408 408
Bridges 613 1 0 612 613
Tunnels 5 0 0 5 5
Railways
Segments 97 0 0 97 97
Bridges 123 0 0 123 123
Tunnels 2 0 0 2 2
Facilities 10 0 0 10 10
Light Rail
Segments 1 0 0 1 1
Bridges 26 0 0 26 26
Tunnels 0 0 0 0 0
Facilities 3 0 0 3 3
Bus Facilities 0 0 0 0 0

5.6.b
Packet Pg. 210 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 138 System Component
Number of Locations
Locations /
Segments
With at
Least
Moderate
Damage
With
Complete
Damage
With Functionality
Greater than 50%
After Day 1 After Day 7
Ferry Facilities 4 0 0 4 4
Port Facilities 77 0 0 77 77
Airport
Facilities 3 0 0 3 3
Runways 6 0 0 6 6
Earthquakes also impact the economy, including loss of business function, damage to inventory (i.e., buildings, transportation, and utility systems), relocation costs, wage loss, and rental loss due to repair and replacement of buildings. Hazus estimates building-related economic losses, including income losses (i.e., wage, capital-related, rental, and relocation losses) and capital stock losses (i.e., structural, non-structural, content, and inventory losses).

Hazus estimates total building related losses were $14.894 Million where 14.0% of the losses were related to business interruption in Contra Costa County. The analysis concluded that the largest loss was sustained by the residential occupancies, which comprised 52% of the total loss. Table 4-86 summarizes the building related economic loss estimates.

Table 4-86. Building Related Economic Loss Estimates (Millions of Dollars) Area Single
Family
Other
Residential Commercial Industrial Others Total
Income
Losses
Wage 0.0 43.7 360.7 30.6 60.3 495.3
CapitalRelated 0.0 18.6 294.6 18.5 8.7 340.3
Rental 72.6 98.4 156.5 11.8 37.1 376.5
Relocation 263.7 67.0 258.4 48.2 177.0 814.2
TOTAL 336.3 227.7 1,070.1 109.0 283.0 2,026.2
Capital
Stock
Losses
Structural 670.4 175.6 467.1 227.9 216.2 1,575.2
NonStructural 3,616.5 1,188.9 1,460.1 747.6 789.9 7,803.0 Content 1,176.7 301.3 728.1 504.7 384.7 3,095.6
Inventory 0.0 0.0 117.1 84.4 10.3 211.8
TOTAL 5,463.7 1,665.8 2,772.3 1,564.6 1,401.1 12,867.5
SUBTOTAL 5,800.0 1,893.5 3,842.7 1,673.7 1,684.1 14,893.7

5.6.b
Packet Pg. 211 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 139 Table 4-87 provides a detailed breakdown in transportation system economic losses in Millions of dollars.

Table 4-87. HAZUS Earthquake Transportation System Economic Losses (Millions of Dollars)
System Component Inventory Value Economic Loss Loss Ratio (%) Highway
Segments 4,025.6 0.0 0.0
Bridges 5,593.8 97.2 1.74
Tunnels 92.1 2.2 2.37
TOTAL 9,711.5 99.4 -
Railways
Segments 4,328.5 0.0 0.0
Bridges 699.9 10.8 1.54
Tunnels 1.8 0.1 3.12
Facilities 26.6 5.4 20.40
TOTAL 5,056.7 16.3 -
Light Rail
Segments 263.2 0.0 0.0
Bridges 3.3 0.0 1.18
Tunnels 0.0 0.0 0.0
Facilities 17.1 3.3 18.94
TOTAL 283.6 3.3 -
Bus
Facilities 0.0 0.0 0.0
TOTAL 0.0 0.0 -
Ferry
Facilities 5.3 0.0 0.0
TOTAL 5.3 0.0 -
Port
Facilities 293.5 56.4 19.21
TOTAL 293.5 56.4 -
Airport
Facilities 24.0 5.3 22.14
Runways 40.5 0.0 0.0
TOTAL 64.5 5.3 -
SUBTOTAL 15,415.1 180.6 -
HAZUS estimates the number of households that are expected to be displaced from their homes due to the earthquake incident and the number of displaced individuals that will require accommodations in temporary public shelters. The model estimates 5,333 households will be displaced due to the earthquake. Of these, 2,628 people (out of a total population of 1,165,927) will seek temporary shelter in public shelters.

Hazus estimates the amount of debris that will be generated by the earthquake event. Debris estimates were divided into two (2) categories – brick/wood and reinforced concrete/steel. The distinction is made because of the different types of materials handling equipment required to handle debris.

5.6.b
Packet Pg. 212 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 140 The analysis estimated that a total of 1,761 million tons of debris will be generated. Of the total amount,

37.0% is comprised of brick/wood and the remainder will be reinforced concrete/steel. If the debris tonnage is converted to an estimated number of truckloads, it will require 70,440 truckloads (25 tons/truck) to remove the debris.

4.6.4.8. FEMA NRI Expected Annual Loss
An earthquake NRI EAL score, and rating represent a community's relative level of expected building and population loss each year due to earthquakes when compared to the rest of the United States. The EAL score is positively associated to a community’s risk; therefore, a higher EAL score results in a higher Risk Index score. Table 4-88 outlines the earthquake EAL for Contra Costa County.

Table 4-88. Earthquake Expected Annual Loss (FEMA National Risk Index) Jurisdiction Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual
Loss
Expected
Annual
Loss
Score
Rating
Contra Costa
County
$156.4
Million
$410.1
Million n/a $566.5 Million 99.8 Very High
Expected annual loss scores are calculated utilizing an equation that combines values for exposure, annualized frequency, and historic loss ratios (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio).

4.6.4.9. FEMA Earthquake Risk Index Score
The earthquake Risk Index score and rating represent a community's relative risk for earthquakes when compared to the rest of the United States. Table 4-89 illustrates the earthquake Risk Index rating and score for Contra Costa County.

Table 4-89. Earthquake Risk Index (FEMA National Risk Index) Jurisdiction Rating Score
Contra Costa County Very High 99.8
Risk Index scores are calculated using an equation that combines scores for Expected Annual Loss due to natural hazards, Social Vulnerability and Community Resilience (Expected Annual Loss x Social Vulnerability / Community Resilience = Risk Index).

5.6.b
Packet Pg. 213 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 141 Table 4-90 represents the Earthquake Failure Total Risk Score for Contra Costa County, based on the Risk Assessment Methodology, as defined in this Plan. For further details on how the probability, extent, vulnerability, and impact factors were calculated, please refer to Table 4-76 through Table 4-79.

Additional details on how the Total Risk Score was calculated can be found in the Risk Assessment Methodology in Section 4.3 of this Plan.

Table 4-90. Earthquake Total Risk Score
Hazard
Event
Probability Consequence Total Risk
Probability
Factor Extent Vulnerability Impact ConsequenceScore
Total Risk
Score*
Earthquake 2 18 17 36 71 68
Consequence: Sum of all weighted factors.

Extent: Sum of the weighted Extent factors.

Vulnerability: Sum of the weighted Vulnerability factors.

Impact: Sum of the weighted Impact factors.

Total Risk Score = Probability x Consequence
* Normalized to 100
Total Risk Score Legend
Classification Probability
Factor Extent Vulnerability Impact ConsequenceScore
Total Risk
Score
Low (L) 1 0 – 6 0 – 6 0 – 12 0 – 24 0 – 24
Medium (M) 2 7 – 12 7 – 12 13 – 26 25 – 50 25 – 54
High (H) 3 13 – 18 13 – 18 27 – 39 51 – 75 55 and above The legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard. The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.

The Total Risk Score is a measure of Probability and Consequence.

5.6.b
Packet Pg. 214 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 142

4.6.5. Flood

4.6.5.1. Description
Floods are the most common and widespread of all weather-related natural disasters and result in more deaths each year than tornadoes, hurricanes, and lightning. A flood is defined as an overflowing of water onto dry land which occurs when the existing channel of a stream, river, canyon, or other watercourses cannot contain excess runoff from rainfall or snowmelt. Table 4-91 lists and describes the different types of flood. Flooding can be damaging, and it can happen with only a few inches of water or covering a house up to the rooftop. Additionally, floods can occur within a few minutes or over a long period of time, and last days, weeks, or longer. 158
Table 4-91. Flood Types 159
Type Description
River Flood
Occurs when water levels rise over the top of riverbanks due to excessive rain from tropical systems making landfall, persistent thunderstorms over the same area for extended periods of time, combined rainfall and snowmelt, or an ice jam.

Inland Flooding
Occurs when moderate precipitation accumulates over several days, intense precipitation falls over a short period, or a river overflow because of an ice or debris jam or dam or levee failure.

Flash Flood
Occurs during heavy or excessive rainfall in a short period of time, generally less than six (6) hours. Flash floods are usually characterized by raging torrents after heavy rains that rip through riverbeds, urban streets, or mountain canyons. They can occur within minutes or a few hours of excessive rainfall. They can also occur even if no rain has fallen, for instance after a levee or dam has failed, or after a sudden release of water by a debris or ice jam.

Coastal Floods
Caused by higher than average high tide and worsened by heavy rainfall and onshore winds (i.e., wind blowing landward from the ocean); the inundation of land areas along the coast.

Storm Surge
An abnormal rise in water level in coastal areas, over and above the regular astronomical tide, caused by forces generated from a severe storm's wind, waves, and low atmospheric pressure.

A floodplain is an area adjacent to a river, creek, or lake that is subject to recurring floods which can provide environmental and flood reduction benefits.
160 Floodplains may change over time from natural
processes, changes in the characteristics of a watershed, or human activity (e.g., construction). River channels change as water moves downstream, acting on the channel banks and the bottom of the channel. Outside a channel curve, the banks are subject to erosion as the water scours against them.

On the inside of a channel curve, the banks receive deposits of sand and sediment transferred from the eroded sites. In areas where flow contains a high-sediment load, the course of a river or stream may shift dramatically during a single flood event.

Flooding in Contra Costa County is typically caused by high-intensity, short-duration (1 to 3 hours) storms concentrated on a stream reach with already saturated soil. Two (2) types of flooding are typical – flash 158 NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Flood Basics. Retrieved from https://www.nssl.noaa.gov/education/svrwx101/floods/.
159 NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Floods. Retrieved from https://www.nssl.noaa.gov/education/svrwx101/floods/types/. 160 Contra Costa County Public Works Department. (2020). Contra Costa County Floodplain Management Program. Retrieved from https://www.contracosta.ca.gov/DocumentCenter/View/8558/Floodplain-PamphletJanuary-2020-PDF?bidId=.

5.6.b
Packet Pg. 215 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 143 floods and riverine flooding. Flash floods that occur suddenly after a brief, but intense downpour, move rapidly, end suddenly, and can occur in areas not generally associated with flooding (e.g., subdivisions not adjacent to a water body and areas serviced by underground drainage systems). Although the duration of these events is usually brief, the damage they cause can be severe. Flash floods cannot be forecast accurately. Riverine floods described in terms of their extent (including the horizontal area affected and the vertical depth of floodwater) and the related probability of occurrence (expressed as the percentage chance that a flood of a specific extent will occur in any given year).

4.6.5.2. Hazard Location
In California, 90% of the natural disasters are flood related. In Contra Costa County, flooding is predominantly confined within traditional riverine valleys. Locally, some natural or human-caused levees separate channels from floodplains and cause independent overland flow paths. Occasionally, railroad, highway, or canal embankments form barriers, resulting in ponding or diversion of the flow. Some localized flooding not associated with stream overflow can occur where there are no drainage facilities to control flows or when runoff volumes exceed the design capacity of drainage facilities. There are 87 creeks, channels, and bodies of water, listed in Table 4-92, that are considered principal flooding sources in the County. 161
Table 4-92. Contra Costa County Flooding Sources
Along Giant Road from Standard
Oil to Rheem Creek Ivy Drive Tributary Pinole Creek
Appian Creek Jonas Hill Creek Refugio Creek
Arroyo Del Hambre Creek Kirker Creek Reliez Creek
Brookside Road Tributary Lafayette Creek Rheem Creek Radeo Creek Carquinez Straight Laguna Creek Sand Creek
Cascade Creek Larch Creek San Francisco Bay
Cerrito Creek Las Trampas Creek San Pablo Bay
Clayton Valley Drain Lauterwasser Creek San Pablo Creek Corliss Drive Tributary Lawlor Creek San Ramon Creek
Deer Creek Line A, DA-40 San Ramon Creek Overflow
Ditch No. 2 Los Medanos Wasteway Sans Crainte Creek
Donner Creek Mangini Creek Sans Crainte Creek Tributary A Dutch Slough Markley Creek Shore Acres Creek
East Antioch Creek Marsh Creek South Branch Moraga Creek Each Branch Green Valley Creek Middle Branch West Antioch Creek South San Ramon Creek (overbank flooding)
East Branch Homestead Creek Miranda Creek South San Ramon Creek East Branch Refugio Creek Mitchell Creek St. Marys Road Tributary East Fork Grayson Creek Moraga Creek Stone Valley Creek 161 Federal Emergency Management Agency. (2017). Flood Insurance Study: Contra Costa County, California and Incorporated Areas. Retrieved from https://www.contracosta.ca.gov/DocumentCenter/View/77626/Volumes-IV?bidId=.

5.6.b
Packet Pg. 216 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 144 Eccleston Avenue Tributary Mount Diablo Creek Suisun Bay Farm Bureau Road Drain Mount Diablo Split Flow Sycamore Creek Galindo Creek Murderers Creek Tice Creek
Garrity Creek North Branch Reliez Creek Tice Creek Overflow Grayson Creek North Branch Stone Valley Creek Walnut Creek Green Valley Creek Orinda Village Overflow West Antioch Creek Grizzly Creek Overhill Creek West Branch Alamo Creek
Happy Valley Creek Overland Cross Section West Branch East Antioch Creek Hidden Valley Creek Pacheco Creek West Branch Refugio Creek Hillcrest Branch East Antioch
Creek Payton Slough Wildcat Creek
Homestead Creek Pine Creek Willow Creek
The Flood Insurance Rate Maps (FIRMs) show the flood zones, floodplain boundaries, and Base Floor Elevation (BFE) and are used for floodplain management, flood insurance ratings, and to determine flood insurance requirements. These maps show areas with a 1% chance of flooding each year, commonly known as the 100-year floodplains, and are shown as the Special Flood Hazard Areas (SFHA) in the FIRM maps. 162 The 500-year floodplains show areas with a 0.2% chance of flooding each year. Figure 4-15 illustrates the Contra Costa County SFHA, including each Flood Zone, and the 500-year floodplain. 162 Ibid.

5.6.b
Packet Pg. 217 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 145 Figure 4-15. Contra Costa County Floodplain

4.6.5.3. Hazard Extent/Intensity
The magnitude of flooding that is used as the standard for floodplain management in the United States is a flood with a probability of occurrence of 1% in any given year. This flood is also known as the 100- year flood or base flood. The most readily available source of information regarding the 100-year flood, as well as the 500-year flood (0.2 % probability of occurrence in any given year), is the FIRMs prepared by FEMA. These maps are used to support NFIP.

4.6.5.4. Warning Time
Flooding can be unexpected and leave a small window of time for evacuation, if it is required. The National Weather Service San Francisco Bay Area Forecast Office is responsible for issuing flood advisories in Contra Costa County. Table 4-93 outlines the flood advisories issued by the NWS as conditions warrant.

5.6.b
Packet Pg. 218 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 146 Table 4-93. NWS Flood Advisories
Type Definition
Flood Advisory
Issued when a flood event warrants notification but is less urgent than a warning.

Advisories are issued for conditions that could cause a significant inconvenience, and if caution is not exercised, could lead to situations that may threaten life and/or property.

Flood Watch
Issued to indicate current or developing conditions that are favorable for flooding. The occurrence is neither certain nor imminent. A watch is typically issued within several hours to days ahead of the onset of possible flooding. In situations where a river or stream is expected to be the main source of the flooding, forecast confidence may allow for a Flood Watch to be issued several days in advance.

Flood Warning
Issued to inform the public of flooding that poses a serious threat to life and/or property. A Flood Warning may be issued hours to days in advance of the onset of flooding based on forecast conditions. Floods occurring along a river usually contain river stage (level) forecasts.

Flash Flood Watch
Issued to indicate current or developing conditions that are favorable for flash flooding.

The occurrence is neither certain nor imminent. A watch is typically issued within several hours to days ahead of the onset of possible flash flooding.

Flash Flood Warning
Issued to inform the public, emergency management and other cooperating agencies that flash flooding is in progress, imminent, or highly likely. Flash Flood Warnings are urgent messages as dangerous flooding can develop very rapidly, with a serious threat to life and/or property. Flash Flood Warnings are usually issued minutes to hours in advance of the onset of flooding.

NWS issues Flash Flood Warnings Impact-Based Warnings for events that occur within approximately six (6) hours of heavy rainfall. The flash flood impact-based warnings fall into the three (3) categories listed in Table 4-94.
163
Table 4-94. NWS Flash Flood Impact Based Warnings
Type Definition
Base Used most of the time when flash flood impact is possible.

Considerable
Used rarely, when there are indications flash flooding capable of unusual severity or impact is imminent or ongoing and urgent action is needed to protect lives and property. Will trigger the Wireless Emergency Alert system.

Catastrophic
Used exceedingly rarely, when a flash flood threat to life and catastrophic damage is occurring or is imminent, and floodwaters have risen or will rise to levels rarely if ever seen. Will trigger the Wireless Emergency Alert system.

When a river reaches flood stage, NWS River Forecast Centers convey the magnitude of observed forecast flooding using flood severity categories based on property damage and public threat. The three (3) flood severity categories are listed in Table 4-95. 164
163 National Weather Service. (2019). Impact-Based Flash Flood Warning. Retrieved from https://www.weather.gov/media/wrn/FFW-IBW-factsheet.pdf. 164 National Oceanic and Atmospheric Administration, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Frequently Asked Questions About Floods. Retrieved from https://www.nssl.noaa.gov/education/svrwx101/floods/faq/.

5.6.b
Packet Pg. 219 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 147 Table 4-95. NWS River Flood Severity Categories
Type Definition
Minor Flooding Minimal or no property damage, but possibly some public threat or inconvenience.

Moderate Flooding Some inundation of structures and roads near streams. Some evacuations of people and/or transfer of property to higher elevations are necessary.

Major Flooding Extensive inundation of structures and roads. Significant evacuations of people and/or transfer of property to higher elevations.

4.6.5.5. Probability and Frequency
The probability of occurrence for flooding in Contra Costa County is medium because significant occurrences of this hazard are likely to occur within 25 years. However, isolated and lower-impact events occur with recurrent regularity. The number of years between floods of any given severity significantly varies due to a naturally changing climate. According to USGS, the reoccurrence interval is based on the probability that the given event will be equaled or exceeded in any given year based on past occurrences.

The concept of reoccurrence intervals and probabilities is outlined in Table 4-96. 165
Table 4-96. Recurrence Intervals and Probabilities of Occurrences Recurrence Interval
(years)
Probability of Occurrence
In any Given Year
Percent Chance of
Occurrence in Any Given Year
100 1 in 100 1
50 1 in 50 2
25 1 in 25 4
10 1 in 10 10
5 1 in 5 20
2 1 in 2 50
Probability of Future Hazard Events
The FEMA NRI analyses flooding data as riverine flooding – when streams and rivers exceed the capacity of their natural or constructed channels to accommodate water flow and water overflows the banks, spilling out into adjacent low-lying, dry land. 166 The riverine flooding annualized frequency value represents the average number of recorded riverine flooding hazard occurrences, in event days, per year over the period of record (24 years). Table 4-97 outlines the annualized frequency for riverine flooding, based on FEMA NRI data, for Contra Costa County.

Table 4-97. Riverine Flooding Annualized Frequency (FEMA National Risk Index) Location Events on Record
(1996 – 2019) Annualized Frequency
Contra Costa County 31 1.3 events per year
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year. 165 United States Geological Surve, New Jersey Water Science Center. (n.d.). Floods: Recurrence Intervals and 100-Year Floods. Retrieved from https://www.usgs.gov/centers/new-jersey-water-science-center/floodsrecurrence-intervals-and-100-year-floods#data. 166 Federal Emergency Management Agency. (n.d.). FEMA National Risk Index: Riverine Flooding. Retrieved from https://hazards.fema.gov/nri/riverine-flooding.

5.6.b
Packet Pg. 220 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 148 Repetitive Loss and Severe Repetitive Loss Properties
FEMA defines a Repetitive Loss property as an NFIP-insured property meeting at least one (1) of the following paid loss criteria since 1978, regardless of any changes in ownership:

Four (4) or more separate claims payments greater than $5,000 each (including building and contents payment).

Two (2) or more separate flood insurance claims payments (building payments only), where the total of the payments is greater than the property’s current value.

Additionally, to receive a designation, at least two (2) of the claim payments must occur within 10 years of one another. 167
A Severe Repetitive Loss property is defined by FEMA as any NFIP-insured single-family or multi-family residential building meeting at least one (1) of the following paid loss criteria since 1978 or from building constructed after 1978, regardless of any changes in ownership:

That has incurred flood-related damage for which four (4) or more separate claims payments have been made, with the amount of each claim (including building and contents payments) exceeding $5,000, and with the cumulative amount of such claims payments exceeding $20,000.

For which at least two (2) separate claims payments (building payments only) have been made under such coverage, with the cumulative amount of such claims exceeding the market value of the building. 168
Additionally, to receive designation, at least (2) of the claims must be within 10 years of each other.

Claims within 10 days of each other will be counted as one (1) claim.

Refer to Section 3.11 of this Plan for a list of Contra Costa County jurisdiction participating in the NFIP and CRS.

Table 4-98 summarizes FEMA Repetitive Loss and Severe Repetitive Loss properties for each of the participating jurisdictions in Contra Costa County. 169 167 Federal Emergency Management Agency, National Flood Insurance Program. (2023). A Policyholder’s Guide to Severe Repetitive Loss. Retrieved from https://agents.floodsmart.gov/sites/default/files/fema_nfippolicyholders-guide-severe-repetitive-loss_brochure_07-2023.pdf. 168 Federal Emergency Management Agency, National Flood Insurance Program. (2021). National Flood Insurance Program: Flood Insurance Manual. Retrieved from https://www.fema.gov/sites/default/files/documents/fema_nfip-all-flood-insurance-manual-apr-2021.pdf. 169 Federal Emergency Management Agency. (2024). OpenFEMA Dataset: NFIP Multiple Loss Properties - v1.

Retrieved from https://www.fema.gov/openfema-data-page/nfip-multiple-loss-properties-v1.

5.6.b
Packet Pg. 221 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 149 Table 4-98. Contra Costa County Repetitive Loss and Severe Repetitive Loss Properties Jurisdiction
Total
Repetitive Loss
Properties
Total Severe
Repetitive Loss
Properties
Mitigated Repetitive
Loss and Severe
Repetitive Loss
Properties
Contra Costa County
22 (13 Single Family; 2 Two
(2)-Four (4) Unit Residential
Building; 1 More than Four
(4) Units Residential
Building; 3 Single-Family
Residential Building; 1
Residential Condo; 2 NonResidential Building)
2 (1 Single Family; 1 More
than Four (4) Units
Residential Building)
1 (1 Single Family)
City of Brentwood 0 0 0
City of Clayton 0 0 0
Town of Danville 0 0 0
City of El Cerrito
3 (2 Single Family; 1
Residential (2, 3, or 4 units)
Non-Condo Building)
0 0
City of Hercules 0 0 0
City of Lafayette
2 (1 Single Family; 1 More
than Four (4) Units
Residential Building)
0 0
City of Martinez
11 (4 Single Family; 3 NonResidential Building; 2 Two
(2)-Four (4) Unit Residential
Building; 1 Single Family
Residential Building; 1
Residential Non-Condo
Building)
1 (1 Single Family) 0
Town of Moraga 0 0 0
City of Oakley 0 0 0
City of Orinda
2 (1 Single Family Residential
Building; 1 Non-Residential
Building)
0 0
City of Pinole 0 0 0
City of Pleasant Hill 3
(3 Single Family) 0 1(1 Single Family)
City of Richmond
5 (4 Single Family; 1 NonResidential Building)
1 (1 Single Family)
1 (1 Single Family)
City of San Pablo 7
(7 Single Family) 0 0

5.6.b
Packet Pg. 222 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 150 Jurisdiction
Total
Repetitive Loss
Properties
Total Severe
Repetitive Loss
Properties
Mitigated Repetitive
Loss and Severe
Repetitive Loss
Properties
City of San Ramon 1
(1 Single Family) 0 0
City of Walnut Creek 3
(3 Single Family)
1 (1 Single Family)
3 (1 Single Family; 2 Two (2)-
Four (4) Unit Residential
Building)
Occupancy Type: Single Family = Single family residence • Two (2)-Four (4) Unit Residential Building = Two (2)-four (4) unit residential building • More Than Four (4) Units Residential Building = Residential building with more than four (4) units • Non-Residential Building = Non-residential building • Non-Residential Business = Non-residential business • Single Family Residential Building = Single-family residential building with the exception of a mobile home or a single residential unit within a multi-unit building • Residential (2, 3, or 4 units) Non-Condo Building = Residential non-condo building with two (2), three (3), or four (4) units seeking insurance on all units • Residential (5 or more units) Non-Condo Building = Residential non-condo building with 5 or more units seeking insurance on all units • Residential Mobile/Manufactured Home = Residential mobile/manufactured home • Residential Condo Association = Residential condo association seeking coverage on a building with one (1) or more units • Single Residential Unit = Single residential unit within a multi-unit building • Non-Residential Mobile/manufactured Home = Non-residential mobile/manufactured home • Non-Residential Building = Non-residential building • Non-Residential Unit = Non-residential unit within a multi-unit building

4.6.5.6. Past Events
The National Center of Environmental Information (NCEI) has reported 58 flood events between 1950 and 2023 in Contra Costa County. Additionally, there have been eight (8) flood disasters declared in Contra Costa County between 1950 and 2023. A notable event occurred between December 26, 2022, through January 17, 2023, a series of six (6) storm systems moved through the San Francisco Bay area resulting in widespread flooding, including river flooding. In Contra Costa County, the event resulted in a series of Flood Warnings and rainfall amounts ranged from 6.2 inches to 20.07 inches. 170 On January 9,
2023, a Major Disaster Declaration (DR-3591) was issued for this event.

Table 4-99 lists flood events that have occurred in the Contra Costa County between 1950 and 2023 according to NCEI.

Table 4-99. Flood Events (1950 – 2023)
Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage
CAMEO ACRES Contra Costa
County CA 12/27/2022 06:00 Flood 0 0 0.01K 0.00K

SAN FRANCISCO

BAY SHORELINE
San Francisco
Bay Shoreline CA 1/12/2021 11:00 Coastal Flood 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
San Francisco
Bay Shoreline CA 1/11/2021 10:30 Coastal Flood 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
San Francisco
Bay Shoreline CA 12/14/2020 10:48 Coastal Flood 0 0 0.00K 0.00K SAN RAMON Contra Costa
County CA 1/16/2020 11:09 Flood 0 0 0.00K 0.00K
MARTINEZ Contra Costa
County CA 1/16/2020 09:31 Flood 0 0 0.00K 0.00K
PACHECO Contra Costa
County CA 12/7/2019 14:28 Flood 0 0 0.00K 0.00K
WALNUT CREEK Contra Costa
County CA 11/26/2019 20:15 Flood 0 0 0.00K 0.00K
ORINDA Contra Costa
County CA 3/6/2019 05:13 Flood 0 0 0.00K 0.00K
170 National Weather Service, San Francisco Bay Area, California Weather Forecast Office. (2023). A Parade of Storms Impact Bay Area. Retrieved from https://www.weather.gov/mtr/AtmosphericRivers_12_2022-01_2023.

5.6.b
Packet Pg. 223 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 151 Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage
LAS JUNTAS Contra Costa
County CA 3/6/2019 02:17 Flood 0 0 0.00K 0.00K
HOOKSTON Contra Costa
County CA 2/26/2019 04:35 Flood 0 0 0.00K 0.00K
OLEUM Contra Costa
County CA 2/14/2019 07:28 Flood 0 0 0.00K 0.00K
RICHMOND Contra Costa
County CA 2/14/2019 06:45 Flood 0 0 100.00K 0.00K
SAN PABLO Contra Costa
County CA 2/13/2019 10:35 Flood 0 0 0.00K 0.00K
VINEHILL Contra Costa
County CA 2/13/2019 08:00 Flood 0 0 0.00K 0.00K
MONSATO Contra Costa
County CA 2/9/2019 23:26 Flood 0 0 0.00K 0.00K
ORINDA Contra Costa
County CA 1/6/2019 16:05 Flood 0 0 0.00K 0.00K
WALNUT CREEK Contra Costa
County CA 11/23/2018 15:29 Flood 0 0 0.00K 0.00K
SELBY Contra Costa
County CA 4/7/2018 00:24 Flood 0 0 0.00K 0.00K
VINEHILL Contra Costa
County CA 3/1/2018 10:38 Flood 0 0 0.00K 0.00K
SELBY Contra Costa
County CA 3/1/2018 09:55 Flood 0 0 0.00K 0.00K
EAST RICHMOND Contra Costa
County CA 1/9/2018 01:30 Flood 0 0 0.00K 0.00K
WALNUT CREEK Contra Costa
County CA 1/9/2018 00:03 Flood 0 0 250.00K 0.00K
ALAMO Contra Costa
County CA 1/8/2018 14:33 Flood 0 0 0.50K 0.00K
WALNUT CREEK Contra Costa
County CA 1/8/2018 09:13 Flood 0 0 0.00K 0.00K
ORINDA Contra Costa
County CA 4/7/2017 22:02 Flood 0 0 0.00K 0.00K
NEROLY Contra Costa
County CA 1/8/2018 20:29 Flood 0 0 0.00K 0.00K
CLYDE Contra Costa
County CA 2/20/2017 20:29 Flood 0 0 0.00K 0.00K
BYRON Contra Costa
County CA 2/20/2017 20:29 Flood 0 0 0.00K 0.00K
ANTIOCH ARPT Contra Costa
County CA 2/20/2017 18:54 Flood 0 0 0.00K 0.00K
PACHECO Contra Costa
County CA 2/20/2017 17:49 Flood 0 0 0.00K 0.00K
TASSAJARA Contra Costa
County CA 2/20/2017 16:00 Flood 0 0 0.00K 0.00K
CLAYTON Contra Costa
County CA 2/20/2017 15:20 Flood 0 0 0.00K 0.00K
EAST RICHMOND Contra Costa
County CA 2/20/2017 07:47 Flood 0 0 0.00K 0.00K
PLEASANT HILL Contra Costa
County CA 2/20/2017 01:40 Flood 0 0 0.00K 0.00K
CLAYTON Contra Costa
County CA 1/10/2017 19:42 Flood 0 0 0.00K 0.00K
GREENBROOK Contra Costa
County CA 12/2/2012 08:56 Flood 0 0 0.50k 0.00K
ORINDA Contra Costa
County CA 12/2/2012 00:00 Flood 0 0 250.00K 0.00K
ORINDA VLG Contra Costa
County CA 1/19/2010 07:00 Flood 0 0 0.00K 0.00K
PITTSBURG Contra Costa
County CA 1/19/2010 06:00 Flood 0 0 0.00K 0.00K
LOS MEDANOS Contra Costa
County CA 1/19/2010 06:00 Flood 0 0 0.00K 0.00K

5.6.b
Packet Pg. 224 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 152 Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage
LOS MEDANOS Contra Costa
County CA 10/13/2009 07:00 Flood 0 0 75.00K 0.00K
COUNTYWIDE Contra Costa
County CA 1/1/2006 00:00 Flood 0 0 22.00M 0.00K
COUNTYWIDE Contra Costa
County CA 12/31/2005 21:00 Flood 0 0 22.00M 0.00K
WALNUT CREEK Contra Costa
County CA 12/14/2002 09:00 Flood 0 0 0.00K 0.00K
ORINDA Contra Costa
County CA 2/13/2000 21:00 Flash Flood 0 0 100.00K 0.00K WALNUT CREEK Contra Costa
County CA 2/7/1998 13:00 Flash Flood 0 0 0.00K 0.00K
PITTSBURG Contra Costa
County CA 2/3/1998 00:00 Flash Flood 0 0 0.00K 0.00K
WALNUT CREEK Contra Costa
County CA 2/3/1998 00:00 Flash Flood 0 0 0.00K 0.00K
COUNTYWIDE Contra Costa
County CA 1/25/1997 05:35 Flash Flood 0 0 0.00K 0.00K
COUNTYWIDE Contra Costa
County CA 1/22/1997 14:15 Flash Flood 0 0 0.00K 0.00K
COUNTYWIDE Contra Costa
County CA 1/2/1997 16:00 Flash Flood 0 0 0.00K 0.00K
COUNTYWIDE Contra Costa
County CA 1/2/1997 11:45 Flash Flood 0 0 0.00K 0.00K
COUNTYWIDE Contra Costa
County CA 1/2/1997 05:52 Flash Flood 0 0 0.00K 0.00K
COUNTYWIDE Contra Costa
County CA 1/1/1997 10:40 Flash Flood 0 0 0.00K 0.00K
COUNTYWIDE Contra Costa
County CA 1/1/1997 09:00 Flash Flood 0 0 0.00K 0.00K
COUNTYWIDE Contra Costa
County CA 1/1/1997 07:18 Flash Flood 0 0 0.00K 0.00K
ORINDA Contra Costa
County CA 12/22/1996 00:00 Flood 0 0 0.00K 0.00K
TOTAL 0 0 44.43M 0.00K

4.6.5.7. Vulnerability and Impacts
Life Safety and Health: Most deaths during a flood occur when vehicles are driven into hazardous floodwater. Vehicles trying to drive through flooded areas or standing water can be swept away and potentially drown. Additionally, a number of hazards can be hidden below floodwaters which is why it is imperative to avoid floodwaters. Floodwater and standing water can make you vulnerable to infectious diseases, chemical hazards, and injuries.171 Floods and their aftermath present numerous threats to public health and safety:

Unsafe food: Floodwaters contain disease-causing bacteria, dirt, oil, human and animal waste, and farm and industrial chemicals. Their contact with food items, including food crops in agricultural lands, can make that food unsafe to eat. Refrigerated and frozen foods are affected during power outages caused by flooding. Foods in cardboard, plastic bags, jars, bottles, and paper packaging may be unhygienic with mold contamination.

Contaminated drinking and washing water, and poor sanitation: Flooding impairs clean water sources with pollutants. The pollutants also saturate into the groundwater. Flooded wastewater treatment plants can be overloaded, resulting in backflows of raw sewage. Private wells can be 171 Centers for Disease Control and Prevention. (2022). Flood Waters or Standing Waters. Retrieved from https://www.cdc.gov/healthywater/emergency/extreme-weather/floods-standingwater.html.

5.6.b
Packet Pg. 225 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 153 contaminated by floodwater. Additionally, private sewage disposal systems can become a cause of infection if they overflow.

Mosquitoes and animals: Floods provide new breeding grounds for mosquitoes in wet areas and stagnant pools. The public should dispose of dead animals that can carry viruses and diseases only in accordance with guidelines issued by local animal control authorities.

Leptospirosis—a bacterial disease associated predominantly with rats—often accompanies floods in developing countries, although the risk is low in industrialized regions unless cuts or wounds have direct contact with disease contaminated floodwaters or animals.

Mold and mildew: Excessive exposure to mold and mildew can cause flood victims, especially those with allergies and asthma, to contract upper respiratory diseases, triggering cold-like symptoms. Molds grow in as short a period as 24 to 48 hours in wet and damp areas of buildings and homes that have not been properly cleaned after flooding (e.g., water-infiltrated walls, floors, carpets, toilets and bathrooms). Very small mold spores can be easily inhaled by human bodies and, in large enough quantities, cause allergic reactions, asthma episodes, and other respiratory problems. Infants, children, seniors, and pregnant women are considered most vulnerable to mold-induced health problems.

Carbon monoxide poisoning: In the event of power outages following floods, some people use alternative fuels for heating or cooking in enclosed or partly enclosed spaces, such as small gasoline engines, stoves, generators, lanterns, gas ranges, charcoal or wood. Built-up carbon monoxide from these sources can poison people and animals.

Hazards when reentering and cleaning flooded homes and buildings: Flooded buildings can pose significant health hazards to people entering them. Electrical power systems can become hazardous, and gas leaks can trigger fire and explosions. Flood debris (e.g., broken bottles, wood, stones and walls) may cause injuries to those cleaning damaged buildings. Additionally, containers of hazardous chemicals may be buried under flood debris. Hazardous dust and mold can circulate through a building and be inhaled by those engaged in cleanup and restoration.

Mental stress and fatigue: People who live through a devastating flood can experience long term psychological impact. The expense and effort required to repair flood-damaged homes places severe financial and psychological burdens on the people affected. Post-flood recovery can cause anxiety, anger, depression, lethargy, hyperactivity, and sleeplessness. There is also a long-term concern among the affected that their homes could be flooded again in the future.

Everyone in Contra Costa County is vulnerable to flooding, but those within the SFHA (i.e., 100-year floodplain) are at a higher risk, followed by those within the 500-year floodplain. However, the underserved and at risk population face unique vulnerabilities and impacts as a result of flooding. These groups include, but are not limited to, households in poverty, low income households, population living in single access roads, people with limited English proficiency, individuals without access to lifelines, the elderly population (including those with access and functional needs), and undocumented individuals. 172
Households in Poverty and Low Income Households: Households in poverty include those with an income at or below $24,300 for a household of four (4). In Contra Costa County, most households considered to live in poverty are located within the 100-year flood zone and households affected by coastal flooding are primarily located within North Richmond, Bay Point, 172 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.

5.6.b
Packet Pg. 226 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 154 and the tracts and islands in the Delta. The low income population includes households with an income of 80% or less of the median income ($104,400) in Contra Costa County. This population tends to be less likely to evacuate in response to emergency incidents. Furthermore, households in poverty and low income households may have fewer financial resources to complete preparedness and recovery activities (i.e., fix flood damage) and the structures are not waterproofed or built above the current 100-year flood elevation. High concentration of this population is located within or near a flood zone or dam inundation area, mostly in the north and east portion of the County.

Individuals Living on Single Access Roads: Includes the population living in areas with a single route in and out (i.e., accessible via one (1) roadway) of the neighborhood or area. This population is uniquely vulnerable to flooding if these roadways are blocked, damaged, and destroyed these individuals can become isolated from the community and emergency services. In Contra Costa County, several neighborhoods and communities in the Delta and in the hillside areas in the central and western side of the County are only accessible via one (1) roadway.

Individuals Without Access to Lifelines: Includes individuals who do not have access to basic technology or services (e.g., transportation, modern communication). This population is vulnerable because not having access to these can create barriers to prepare and respond to emergency events (e.g., flooding), may be unable to evacuate in a timely manner, and may become isolated if transit services are not operating. For example, this population may be unaware of an approaching weather event and may be unable to evacuate in a timely manner in the event an evacuation order is issued.

Senior (65 years old and over): The elderly population (i.e., seniors), especially those with access and functional needs, may have physical limitations that make it harder to evacuate in the event of an emergency, such as flooding. Furthermore, the elderly population may lack access to social connections and community support that can assist in preparing for and responding to emergency events, evacuating, improving home resiliency, managing medical needs, and locating support services. A high concentration of the elderly population lives in central Contra Costa County, Bethel Island, eastern part of Richmond, and several parts of Walnut Creek.

Undocumented Individuals: Includes people who do not have formal permission to live in the United States (i.e., do not have citizenship, permanent residency, visas, or other similar status).

This population is most likely to fall in the households in poverty and low income categories, which are considered to be at risk populations during a flooding event and are more likely to live in low lying areas in structures that are not waterproofed or build above the 100-year flood elevations.

5.6.b
Packet Pg. 227 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 155 Table 4-100 summarizes the vulnerable and at-risk population for flooding in Contra Costa County.

Table 4-100. Vulnerability and At Risk Population
Category Estimate Percent
Households in Poverty173 7,600 12.0%
Low Income Households174 25,340 41.0%
Spanish Spoken at Home175 204,442 18.7%
Speak English “Less than very
well”176 158,965 38.2%
Language Other than English177 416,505 38.0%
Foreign Born178 312,050 27.0%
Households Without Vehicle179 8,872 1.6%
65 Years and Over180 201,136 17.4%
Seniors (65 years and over) Living
Alone181 45,672 22.7%
Undocumented Individuals182 There are no official counts of how many undocumented individuals live in Contra Costa County, but in 2019 there was an estimate of 63,000.

Table 4-106 outlines the vulnerability of the total population exposed to floods, and Table 4-107 outlines the flood impacts to population and life safety, underserved/equity population, and essential operations, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Property Damage and Critical Infrastructure: In Contra Costa County, there is a range from the large, state-owned bridges that carry interstate freeways, to locally owned bridges that carry rural roads and pedestrians over small creeks. Countywide, there are over 400 bridges where approximately 80 are owned by the County and 160 are owned by Caltrans. There are 26 bridges that are within the 100-year flood zone and dam inundation areas. Some of these bridges are located in low lying areas that could become flooded during a heavy rainfall event. Additionally, flood control infrastructure (i.e., levees, dikes, 173 Ibid.
174 Ibid.
175 United States Census Bureau. (2022). S1601: Language Spoken at Home (2022: ACS 1-Year Estimates Subject Tables). Retrieved from https://data.census.gov/table/ACSST1Y2022.S1601?g=050XX00US06013. 176 Ibid.
177 Ibid.
178 United States Census Bureau. (2022). DP02: Selected Social Characteristics in the United States (2022: ACS 1-Year Estimates Data Profiles). Retrieved from
https://data.census.gov/table/ACSDP1Y2022.DP02?g=050XX00US06013. 179 United States Census Bureau. (2022). S0801: Commuting Characteristics by Sex. Retrieved from https://data.census.gov/table/ACSST1Y2022.S0801?g=050XX00US06013. 180 United States Census Bureau. (2022). DP05: Demographics and Housing Estimates (2022: ACS 1-Year Estimates Data Profiles). Retrieved from
https://data.census.gov/table/ACSDP1Y2022.DP05?g=050XX00US06013. 181 United States Census Bureau. (2022). DP02: Selected Social Characteristics in the United States (2022: ACS 1-Year Estimates Data Profiles). Retrieved from
https://data.census.gov/table/ACSDP1Y2022.DP02?g=050XX00US06013. 182 Migration Policy Institute. (2019). Profile of the Unauthorized Population: Contra Costa County, CA. Retrieved from https://www.migrationpolicy.org/data/unauthorized-immigrant-population/county/6013.

5.6.b
Packet Pg. 228 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 156 and drainage channels), meant to prevent the creeks, Delta, and other bodies of water from overflowing and causing floods can fail and cause flooding in these areas. Although the Contra Costa County Flood Control District is responsible for local flood control projects, many of these levees and drainage facilities in the Delta region of the County are privately owned and operated. Interstate 680 and 80, and State Route 4, along with many regional roadways, are within flooding zones. Flooding to these roadways and other local roadways can cause major disruptions to local and regional transportation, transit, and commuters.

There are three (3) standard rail lines that run through Contra Costa County which are operated by Union Pacific, Burlington Northern Santa Fe, and Richmond Pacific Railroad Corporation. These run along the western, northern, and eastern boundaries of the County, along Interstate 80, State Route 4, and Byron Highway. The aforementioned rail lines are used for freight trains; however, the Capitol Corridor commuter train runs along the Union Pacific railway. Additionally, the Bay Area Rapid Transit District (BART) operates its own separate rail lines used exclusively for public transit. Two (2) BART rail lines are located in the County – one beginning in Richmond and heading south toward Berkeley and another one in the central part of the County extending from the City of Orinda to the City of Antioch. The BART, Amtrak, and the freight lines are located within the flood areas in coastal and northern Contra Costa County. Flooding can cause damage to the tracks and result in the system to completely shutting down.

There are 10 wastewater treatment plants in the County which treat wastewater for residents within cities and unincorporated County. Two (2) of these wastewater treatment plants are within the 100-year and 500-year floodplain. Furthermore, one (1) is located within a dam inundation area, including the West Contra Costa and Pinole-Hercules plants. Additionally, if the Delta levee fails the Mokelumne Aqueduct could be exposed to coastal flooding. The Contra Costa Canal and the Clifton Court Forebay are also within the coastal flooding area. In the event that these levees fail during a coastal flooding event, these water and wastewater infrastructure would also fail resulting in the contamination of freshwater, reducing the availability of drinking and agricultural water.

In Contra Costa County, there are approximately 61 industrial buildings within the coastal flooding areas, 68 are within the 500-year floodplain. Industrial buildings located outside the 100-year floodplain are unlikely to be waterproofed or flood resistant. If any of these structures are damaged due to flooding, it can increase the potential of a hazardous materials release.183 There are a total of 554 critical assets (i.e., schools, nursing homes, fire stations, police stations, and hospitals) throughout the County, and 14 (2.5%) are located within the 100-year floodplain (i.e., SFHA) and 24 (4.3%) are located within the 500-year floodplain. Table 4-101 provides a breakdown of critical assets that are located within the floodplains in Contra Costa County.

Table 4-101. Critical Assets in the 100-Year and 500-Year Floodplains Asset Estimate Percent
(of total asset)
100-Year Floodplain
Schools (public schools, private schools) 5 1.4%
Nursing Homes 1 1.3%
Fire Stations 7 8.6%
183 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.

5.6.b
Packet Pg. 229 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 157 Asset Estimate Percent
(of total asset)
Police Stations 1 4.2%
Hospitals 0 0.0%
500-Year Floodplain
Schools (public schools, private schools) 12 3.3%
Nursing Homes 4 5.1%
Fire Stations 7 8.6%
Police Stations 0 0.0%
Hospitals 1 9.1%
Locations that are directly flooded experience the greatest economic impact. In these areas, renovations of commercial buildings may be necessary, disrupting associated services. Significant damage may occur in agricultural areas, with destruction of crops and other agricultural products. The tourism industry may be affected by major flood events, as popular vacation areas tend to overlap flood hazard zones.

Also, flooding in major roadways can disrupt local and regional transportation and transit and if commuters in the Bay Area are unable to reach their jobs, large sections of the economy can be affected.

Additionally, flooding can cause damage to the rail and BART lines resulting in a shutdown which can disrupt regional transit networks that are essential to the economic activity of the County and region. Loss of power and communications may occur; and drinking water and wastewater treatment facilities may be temporarily out of operation.

Table 4-106 outlines the total property value exposed to floods and how the changes in development in the past five (5) years have affected the vulnerability of the community to floods. Table 4-107 outlines the flood impacts on total property damage, potential future development, and the economy, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Building damage as a result of a 100-year flood analysis was estimated using Hazus. In addition, annualized losses were calculated. Refer to the Hazus portion at the end of this section (Section 4.6.5.7).

Environment: The environment vulnerable to flood hazard is the same as the environment exposed to the hazard. Loss estimation platforms such as Hazus are not currently equipped to measure environmental impacts of flood hazards. The best gauge of vulnerability of the environment would be a review of damage from past flood events. Loss data that segregates damage to the environment was not available at the time of this Plan. Capturing this data from future events could be beneficial in measuring the vulnerability of the environment for future updates. While the vulnerability assessment focuses on human vulnerability to flood events, the impact of human activities on flooding is also worth noting. Due to negative impacts of floods, many structural and other measures have been devised to limit how far a floodplain can extend. However, floodplains have many natural and beneficial functions, and disruption of natural systems can have long-term consequences for entire regions.

In Contra Costa County, the wetland ecosystems, located adjacent to the San Francisco Bay and Delta, include permanent wetland, seasonal wetland, fresh emergent wetland, alkali wetland, and marshes.

Wildlife in these ecosystems includes great blue heron, great egret, wood duck, green-winged teal, mallard, California red-legged frog, western pond turtle, garter snakes, western spadefoot toad, western toad, California tiger salamander, tri-colored blackbird, and vernal pool fairy shrimp. It is forecast that coastal flooding will inundate most of the wetland and tidal marshes in Contra Costa County by 2070.

5.6.b
Packet Pg. 230 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 158 The wildlife habitat, recreation, and flood protection that these ecosystems provide may not be able to be sustained.

Additionally, flooding can disrupt water and wastewater services, and failure of these treatment plants can result in sewer systems to backup which can potentially contaminate creeks, streams, and water systems with raw sewage. Contra Costa County currently has 10 wastewater treatment plants, some of which are located within the 100-year and 500-year floodplain. Furthermore, industrial buildings that sustain flood damage can result in a hazardous materials event which can contaminate soil, water, and aid. Contra Costa County has approximately 270 industrial buildings, many of which are within flooding areas.
184
Table 4-107 outlines flood impacts on the environment, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Changes in Development and Impact of Future Development: There have been no significant changes in development that have affected the risks associated with flooding. Future increases in population within the SHFA may expose more of the population to floods. Growth over the past decade has considerably increased. Between 2010 and 2022, as outlined in Table 3-3, the population in Contra Costa County grew 10.6%, from 1,046,025 to 1,156,966 residents. The Bay Area Association of Governments (ABAG) growth forecasts predict a steady increase in households through 2050. From 2015 to 2050, ABAG projects that the County’s number of households will grow by 44%.185 This increase in population can add an additional strain to first responders in the event of an evacuation due to flooding.

Table 4-106 outlines how the changes in development in the past five (5) years have affected the vulnerability of the community to floods. Table 4-107 outlines the flood impacts on potential future development, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Effects of Climate Change in Severity of Impacts: As global average temperatures increase, evaporation increases adding moisture into the atmosphere which results in more precipitation. 186 In California and western United states, observations of climate change have shown sea level rise is expected to continue to increase flooding on coastal areas. Additionally, scientists project that the frequency and intensity of heavy rainfall (e.g., atmospheric rivers), and associated floods in the County will increase. Although heavy precipitation does not necessarily result in flooding, the potential increases and in some location moderate amounts of precipitation can lead to serious damage.187 Table 4-102 indicates the 25-year precipitation projections in Contra Costa County. 188 Table 4-103
outlines the flood associated climate indicators for Contra Costa County projected through the end of the century.189
184 Ibid.
185 Bay Area Association of Government. (2020). Plan Bay Area 2050 Final Blueprint Growth Pattern. Retrieved from https://planbayarea.org/digital-library/plan-bay-area-2050-final-blueprint-growth-pattern. 186 Environmental Protection Agency. (n.d.). Climate Change Indicators: U.S. and Global Precipitation. Retrieved from https://www.epa.gov/climate-indicators/climate-change-indicators-us-and-global-precipitation. 187 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.
188 Northeast Regional Climate Center. (n.d.). Neighborhoods at Risk: Climate Projections. Retrieved from https://nar.headwaterseconomics.org/.
189 Climate Mapping for Resilience and Adaptation. (n.d.). Climate Mapping for Resilience and Adaptation Assessment Tool. Retrieved from https://livingatlas.arcgis.com/assessment-tool/explore/details.

5.6.b
Packet Pg. 231 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 159 Table 4-102. 25-Year Precipitation Projections for Contra Costa County Higher Emissions (RCP8.5)
By 2048, Contra Costa County is expected to have a 0.4 inches increase (from 19.6 inches to 20.1 inches) in average annual precipitation.

Lower Emissions (RCP4.5)
By 2048, Contra Costa County is expected to have a 0.15 inches increase (from 19.11 inches to 19.26 inches) in average annual precipitation.

Table 4-103. Future Climate Indicators for Contra Costa County Indicators
Modeled
History
(1976 – 2005)
Early Century
(2015 – 2044)
Mid Century
(2035 – 2064)
Late Century
(2070 – 2099)
Lower
Emissions
Higher
Emissions
Lower
Emissions
Higher
Emissions
Lower
Emissions
Higher
Emissions
Min – Max Min – Max Min – Max Min – Max Min – Max Min – Max Min – Max Precipitation
Average annual total
precipitation
19 inches 19 inches 20 inches 20 inches 20 inches 20 inches 21 inches 17 – 21 16 – 25 17 – 24 17 – 26 16 – 25 16 – 25 14 – 27 Days per year with
precipitation
(Wet Days)
84 days 82 days 82 days 80 days 80 days 80 days 77 days 80 – 88 74 – 91 74 – 91 68 – 91 69 – 98 70 – 90 58 – 94 Maximum period of
consecutive wet days
11 days 11 days 12 days 11 days 11 days 11 days 11 days 10 – 12 10 – 14 10 – 14 9 – 14 9 – 15 10 – 15 8 – 17
Temperature Thresholds
Annual days with total
precipitation greater
than 1 inch
2 days 3 days 3 days 3 days 3 days 3 days 4 days
2 – 3 2 – 4 2 – 4 2 – 5 2 – 5 2 – 5 2 – 7
Annual days with total
precipitation greater
than 2 inches
0 days 0 days 0 days 0 days 0 days 0 days 0 days
0 – 0 0 – 1 0 – 1 0 – 1 0 – 1 0 – 1 0 – 1
Annual days with total
precipitation greater
than 3 inches
0 days 0 days 0 days 0 days 0 days 0 days 0 days
0 – 0 0 – 0 0 – 0 0 – 0 0 – 0 0 – 0 0 – 0
Annual days that
exceed 99th percentile
precipitation
4 days 5 days 5 days 5 days 5 days 5 days 6 days
3 – 7 3 – 8 3 – 8 3 – 8 3 – 9 3 – 9 4 – 11
Days with maximum
temperature below
32°F
0 days 0 days 0 days 0 days 0 days 0 days 0 days
0 – 0 0 – 0 0 – 0 0 – 0 0 – 0 0 – 0 0 – 0
Table 4-107 outlines the climate change impacts to floods in Contra Costa County, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

5.6.b
Packet Pg. 232 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Urban/Flash Flooding Medium Significant hazard event is likely to occur within 25 years. 2 N/A Riverine/Creek Flooding Medium Significant hazard event is likely to occur within 25 years. 2 N/A Urban/Flash Flooding
Extent/Intensity High Historical and/or probabilistic models/studies for this hazard indicate the possibility of a high-intensity incident. 3 9Catastrophic Medium Catastrophic hazard event is likely to occur at least once between 11 and 50 years. 2 6 Riverine/Creek Flooding
Extent/Intensity Medium Historical and/or probabilistic models/studies for this hazard indicate the possibility of a medium-intensity incident. 2 6Catastrophic Medium Catastrophic hazard event is likely to occur at least once between 11 and 50 years. 2 6 Urban/Flash Flooding
Population Exposure Medium 15% to 29% of the population (including underserved population) is exposed to the hazard. 2 6Property Exposure Medium 10% to 24% of the total assessed property value is exposed to the hazard. 2 4Changes inDevelopment Medium The changes in development have increased the vulnerability of the community to the hazard between 5% and 9%. 2 2 Riverine/Creek Flooding
Population Exposure Low 14% or less of the population is exposed to the hazard. 1 3Property Exposure Low 9% or less of the total assessed property value is exposed to a hazard. 1 2Changes inDevelopment Medium The changes in development have increased the vulnerability of the community to the hazard between 5% and 9%. 2 2

5.6.b
Packet Pg. 233 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Urban/Flash Flooding
P
o
p
ulatio
n an
d
Life
Safety
Medium
Populations exposed to this hazard are likely to experiencesome adverse impacts, such as injuries requiring acutemedical care. 2 6
Un
derserved/E
q
uity
Medium
Underserved populations exposed to the hazard are likely toexperience some adverse/disproportionate impacts, such asinjuries requiring acute medical care. 2 6
Pro
perty
Damage High
More than $5 Million in property damages is expected from asingle major hazard event, or damages are expected to occurto 15% or more of the property value within the jurisdiction. 3 6
Eco
n
o
mic Medium
Total economic impact is likely to be greater than $500,000,but less than or equal to $10 Million. 2 2
En
viro
n
mental Medium
Environmental impact from a single major hazard event islikely to be localized, requiring some outside resources andsupport; and/or repair, clean-up, restoration, or preservationwork. 2 2
Es
sential Operatio
n
s
Medium
Impact between 24 and 72 hours on the ability of thejurisdiction to meet the essential day-to-day operationaldemands and needs of the com munity from a single major
hazard event.
2 2
Future Develo
p
ment Medium
Future development trends will increase theimpact/consequence of this hazard, but not significantly. 2 2
Climate C
han
ge High
Climate Change trends will significantly increase the risk ofthis hazard and its impacts. 3 3
Riverine/Creek Flooding
P
o
p
ulatio
n an
d
Life
Safety
Medium
Populations exposed to this hazard are likely to experiencesome adverse impacts, such as injuries requiring acutemedical care. 2 6
Un
derserved/E
q
uity Low
Underserved populations exposed to the hazard are likely toexperience minimal adverse/disproportionate impacts, suchas ambulatory injuries. 1 3
Pro
perty
Damage High
More than $5 Million in property damages is expected from asingle major hazard event, or damages are expected to occurto 15% or more of the property value within the jurisdiction. 3 6
Eco
n
o
mic Medium
Total economic impact is likely to be greater than $500,000,but less than or equal to $10 Million. 2 2
En
viro
n
mental Medium
Environmental impact from a single major hazard event islikely to be localized, requiring some outside resources andsupport; and/or repair, clean-up, restoration, or preservationwork. 2 2

5.6.b
Packet Pg. 234 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Essential Operations Medium
Impact between 24 and 72 hours on the ability of thejurisdiction to meet the essential day-to-day operationaldemands and needs of the community from a single majorhazard event. 2 2
Future Development Medium Future development trends will increase the impact/consequence of this hazard, but not significantly. 2 2Climate Change High Climate Change trends will significantly increase the risk of this hazard and its impacts. 3 3

5.6.b
Packet Pg. 235 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 163 HAZUS
Scenario: 100-Year Flood
Building damage as a result of a 100-year flood analysis was estimated using Hazus. In addition, annualized losses were calculated. Hazus estimates that there are 341,451 buildings in the region which have been an aggregated total replacement of $218.5 Million. Approximately 91.1% of the buildings are associated with residential housing. Table 4-108 provides a general distribution of the building value within Contra Costa County. In terms of building construction types found in the County, wood frame construction makes up 89.0% of the building inventory and the remaining 11.0% is distributed between the other general building types (i.e., steel, concrete, precast, reinforced masonry, unreinforced masonry, manufactured housing).

Table 4-108. Contra Costa County Population and Building Value Data Population Residential Building
Value
Non-Residential
Building Value Total
1,165, 466 $158.1 Million $60.3 Million $218.5 Million
The total economic loss estimated for the flood is $9.952 Million, representing 24.1% of the total replacement value of the scenario buildings. HAZUS estimates that about 8,489 buildings will be at least moderately damaged. This is over 62% of the total number of buildings in the scenario. There is an estimated 559 building that will be completely destroyed. Table 4-109 summarizes the expected damage by general occupancy for the buildings in Contra Costa County.

Table 4-109. 100-Year Flood Expected Building Damage by Occupancy Damage
Level 1 – 10 11 – 20 21 – 30 31 – 40 41 – 50 >50
Occupancy Count % Count % Count % Count % Count % Count % Agriculture 0 0 0 0 0 0 0 0 0 0 0 0
Commercial 223 36 370 59 27 4 6 1 0 0 0 0
Education 4 100 0 0 0 0 0 0 0 0 0 0
Government 45 55 37 44 0 0 1 1 0 0 0 0
Industrial 23 28 40 49 8 10 9 11 1 1 0 0
Religion 3 50 3 50 0 0 0 0 0 0 0 0
Residential 2,333 23 3,786 37 1,854 18 1,154 11 634 6 559 5 TOTAL 2,633 4,236 1,889 1,170 635 559

5.6.b
Packet Pg. 236 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 164 Table 4-110 summarizes the expected damage by general building type.

Table 4-110. Expected Building Damage by Building Type
Building
Type
1 – 10 11 – 20 21 – 30 31 – 40 41 – 50 >50
Count % Count % Count % Count % Count % Count %
Concrete 113 36 167 53 30 9 5 2 3 1 0 0
Manufactured
Housing 26 9 24 8 22 7 0 0 21 7 204 69
Masonry 83 31 141 53 35 13 5 2 3 1 0 0
Steel 49 33 81 54 14 9 3 2 2 1 0 0
Wood 2,312 23 3,774 38 1,756 18 1,143 11 603 6 355 4
For essential facilities, there are 14 hospitals in the County with a total bed capacity of 1,804 beds. There are 384 schools, 78 fire stations, 35 police stations and two (2) emergency operation centers. With respect to high potential loss facilities, there are no dams identified within the inventory. The inventory also includes no hazardous material sites, no military installations and no nuclear power plants.

The Hazus model estimates the time to restore critical facilities to fully functional use. Before the flood event, Contra Costa County had 1,804 hospital beds available for use. On the day of the flood event, Hazus estimates that 1,804 hospital beds (100%) are available. Table 4-111 summarizes the expected damage to essential facilities in Contra Costa County. None of the essential facilities listed are expected to be damaged due to the flood event.

Table 4-111. 100-Year Flood Expected Damage to Essential Facilities Facility Total At Least
Moderate
At Least
Substantial Loss of Use
Hospitals 14 0 0 0
Schools 384 0 0 0
Emergency Operations Center 2 0 0 0
Police Stations 35 0 0 0
Fire Stations 78 0 0 0
TOTAL 384 0 0 0
Flood events also impact the economy, including loss of business function, damage to inventory (i.e., buildings, transportation, and utility systems), relocation costs, wage loss, and rental loss due to repair and replacement of buildings. Hazus estimates building-related economic losses, including income losses (i.e., wage, capital-related, rental, and relocation losses) and capital stock losses (i.e., structural, non-structural, content, and inventory losses).

Hazus estimates total building related losses were $5.001 Million where 50.0% of the losses were related to business interruption in Contra Costa County. The analysis concluded that the largest loss was sustained by the residential occupancies, which comprised 52% of the total loss.

The total building related losses were $5.001 Million. 50% of the estimated losses were related to the business interruption of Contra Costa County. The residential occupancies made up 30.6% of the total

5.6.b
Packet Pg. 237 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 165 loss. Table 4-112 provides a summary of the losses associated with the building damage in Millions of dollars.

Table 4-112. 100-Year Flood Building Related Economic Loss Estimates (Millions of Dollars) Area Residential Commercial Industrial Others Total
Building
Loss
Building 1,481.3 352.1 101.3 96.3 2,030.9
Content 867.8 1,099.4 218.6 544.0 2,729.7
Inventory 0.0 195.2 31.4 14.0 240.7
TOTAL 2,349.1 1,646.7 351.3 654.3 5,001.3
Business
Interruptions
Income 39.6 778.0 7.4 193.4 1,018.6
Relocation 343.0 261.8 8.4 132.6 745.7
Rental
Income 221.8 169.8 2.1 27.4 421.0
Wage 93.2 880.7 12.8 1,778.7 2,765.4
TOTAL 697.5 2,090.3 30.6 2,132.3 4,950.6
SUBTOTAL 3,046.5 3,737.0 381.9 2,786.6 9,952.0
HAZUS estimates the number of households that are expected to be displaced from their homes due to the flood incident and associated potential evacuation, and the number of displaced individuals that will require accommodations in temporary public shelters. The model estimates 23,642 households (70,926 people) will be displaced due to the flood. Displacement includes households evacuated from within or very near to the inundated area. Of these, 4,961 people (out of a total population of 1,165,466) will seek temporary shelter in public shelters.

Hazus estimates the amount of debris that will be generated by the flood event. Debris estimates were divided into three (3) categories – finishes (e.g., dry wall, insulation), structural (e.g., wood, brick), and foundations (e.g., concrete slab, concrete block, and rebar). The distinction is made because of the different types of materials handling equipment required to handle debris.

The analysis estimated that a total of 78,790 tons of debris will be generated. Of the total amount, 78.0% is comprised of finishes, 11.0% is structural, and 12.0% is foundation. If the debris tonnage is converted to an estimated number of truckloads, it will require 3,152 truckloads (25 tons/truck) to remove the debris.

4.6.5.8. FEMA NRI Expected Annual Loss Estimates
A riverine flooding NRI EAL score, and rating represent a community's relative level of expected building, population, and agriculture loss each year due to riverine flooding when compared to the rest of the United States. The EAL score is positively associated to a community’s risk; therefore, a higher EAL score results in a higher Risk Index score. Table 4-113 outlines the riverine flooding EAL for Contra Costa County.

5.6.b
Packet Pg. 238 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 166 Table 4-113. Riverine Flooding Expected Annual Loss (FEMA National Risk Index) Jurisdiction Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual
Loss
Expected
Annual
Loss
Score
Rating
Contra Costa
County $4.0 Million $4.1 Million $291,636 $8.4 Million 96.3 Very High Expected annual loss scores are calculated utilizing an equation that combines values for exposure, annualized frequency, and historic loss ratios (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio).

4.6.5.9. FEMA Flooding Risk Index Scores
The riverine flooding Risk Index score and rating represent a community's relative risk for riverine flooding when compared to the rest of the United States. Table 4-114 illustrates the riverine flooding Risk Index rating and score for Contra Costa County.

Table 4-114. Riverine Flooding Risk Index (FEMA National Risk Index) Jurisdiction Rating Score
Contra Costa County Very High 96.2
Risk Index scores are calculated using an equation that combines scores for Expected Annual Loss due to natural hazards, Social Vulnerability and Community Resilience (Expected Annual Loss x Social Vulnerability / Community Resilience = Risk Index).

Table 4-115 represents the Flooding Total Risk Score for Contra Costa County, based on the Risk Assessment Methodology, as defined in this Plan. For further details on how the probability, extent, vulnerability, and impact factors were calculated, please refer to Table 4-104 through Table 4-107.

Additional details on how the Total Risk Score was calculated can be found in the Risk Assessment Methodology in Section 4.3 of this Plan.

Table 4-115. Flooding Total Risk Score
Hazard
Event
Probability Consequence Total Risk
Probability
Factor Extent Vulnerability Impact ConsequenceScore
Total Risk
Score*
Urban/Flash Flooding 2 15 12 29 56 55
Riverine/Creek Flooding 2 12 7 29 48 48
Consequence: Sum of all weighted factors.

Extent: Sum of the weighted Extent factors.

Vulnerability: Sum of the weighted Vulnerability factors.

Impact: Sum of the weighted Impact factors.

The Total Risk Score is a measure of Probability and Consequence.

5.6.b
Packet Pg. 239 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 167

4.6.6. Landslide

4.6.6.1. Description
A landslide is the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of "mass wasting," which denotes any downslope movement of soil and rock under the direct influence of gravity. The landslide term is comprised of five (5) types of slope movement – falls, topples, slides, spreads, and flows – which are further subdivided by the type of geologic material (i.e., bedrock, debris, or earth). 190 Slope movement occurs when forces acting downslope exceed the strength of the earth’s material that compose the slope. The modes of slope movement are listed in Table 4-116. 191
Table 4-116. Types of Slope Movement
Type Description
Falls Masses of soil or rock that dislodge from steep slopes and free fall, bounce, or roll downslope.

Topples Move by the forward pivoting of a mass around an axis below the displaced mass.

Slides
Displaced masses of material along one (1) or more discrete planes. There are two (2) types of sliding – rational and translational.

Rotational sliding the slide plane is curved and the mass rotates backwards around an axis parallel to the slope.

Translational sliding the failure surface is more or less planar and the mass moves parallel to the ground surface.

Lateral Spreads Move by horizontal extension and shear or tensile fractures and are commonly induced by liquefaction of material in an earthquake.

Flows Mobilize as a deforming, viscous mass without a discrete failure plane.

Complex Occurs when more than one (1) type of movement occurs sequentially during a failure.

Composite Occurs when more than one (1) type of movement does not occur sequentially during a failure.

Landslides are an important natural process because they shape the Earth’s landscape and contribute to the overall environmental quality of a region. However, when landslides impact people, property, or infrastructure it is considered a natural hazard. Landslides can occur in slopes already on the verge of movement by rainfall, snowmelt, changes in water level, stream erosion, changes in ground water, earthquake, volcanic activity, disturbance by human activities, or any combination of these factors. 192 The California Department of Conservation (CDC) classifies landslides into the six (6) categories listed in Table 4-117.
190 United States Geological Survey. (n.d.). What is a Landslide and What Causes One? Retrieved from https://www.usgs.gov/faqs/what-landslide-and-what-causes-one. 191 California Department of Conservation. (n.d.). Landslides. Retrieved from https://www.conservation.ca.gov/cgs/landslides.
192 United States Geological Survey. (n.d.). What is a Landslide and What Causes One? Retrieved from https://www.usgs.gov/faqs/what-landslide-and-what-causes-one.

5.6.b
Packet Pg. 240 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 168 Table 4-117. Types of Common Landslide 193
Type Description
Earth Flows
The majority of the soil materials are fine-grained, cohesive silt and clay and occur in moderately steep slopes (10% to 30% grade). Earth flows are slow moving (centimeters or millimeters over a period of days or weeks) and are often triggered by periods of prolonged rainfall and sometimes do not occur until well after a rainfall event or the rainy season.

Debris Flows
The majority of the soil is coarse-grained (e.g., fine sand to boulder size particles) and non-cohesive and commonly begin as a slide of a shallow mass of soil and weathered rock. Debris flows tend to be small in areal extent and their deposits are relatively thin.

Debris Slide
The majority of the soil is coarse-grained, most common in unconsolidated sandy or gravelly units, but also are common in residual soils that form in-place weathering of relatively hard rock. Debris slides tend to occur on very steep slopes (60% to 70% grade) where the base of the slope is undercut with erosion. These move at rates between meters per day to meters per minute and are often triggered after a single heavy rainstorm or series to storms that deliver enough rain to trigger a debris slide.

Rockslides
Involves bedrock in which the rock that moves remains largely intact for at least a portion of the movement. Rockslides occur in a variety of sizes on a variety of gradients (35% to 70% grade) and have a range of triggering mechanism.

Rock Falls
Occurs when a mass of rock detaches from a steep slope by sliding, spreading, or toppling and descends mainly through the air by falling, bouncing, or rolling. Rock falls can be triggered by intense rain, earthquakes, and freeze-thaw wedging.

Additionally, earthquake shaking can induce underwater landslides (i.e., submarine landslides) which can cause tsunamis potentially resulting in damage to coastal areas.

4.6.6.2. Hazard Location
The best available predictor of where movement of slides and earth flows might occur is the location of past movements. Past landslides can be recognized by their distinctive topographic shapes, which can remain in place for thousands of years. Most landslides recognizable in this fashion range from a few acres to several square miles and many show no evidence of recent movement and are not currently active. A small proportion of them may become active in any given year, with movements concentrated within all or part of the landslide masses or around their edges.

The recognition of ancient dormant mass movement sites is important in the identification of areas susceptible to flows and slides because they can be reactivated by earthquakes or by exceptionally wet weather. Also, because they consist of broken materials and frequently involve disruption of groundwater flow, these dormant sites are vulnerable to construction-triggered sliding.

Landslide susceptibility maps describe the relative likelihood of future land sliding based solely on the intrinsic properties of a location or site. There are three (3) site factors that most determine susceptibility – prior failure, rock or soil strength, and steepness of slope. 194 Figure 4-16 illustrates landslide susceptibility in Contra Costa County. Western Contra Costa County has a very high susceptibility to landslides. Meanwhile, central Contra Costa County susceptibility to landslide is medium and the eastern part of the County susceptibility is low.
193 California Department of Conservation. (n.d.). Landslides. Retrieved from https://www.conservation.ca.gov/cgs/landslides.
194 California Department of Conservation. (n.d.). Landslides. Retrieved from https://www.conservation.ca.gov/cgs/landslides.

5.6.b
Packet Pg. 241 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 169 Figure 4-16. Landslide Susceptibility in Contra Costa County

4.6.6.3. Hazard Extent/Intensity
In the United States, landslides cause billions of dollars in damages and kill between 25 and 50 people annually. Casualties are primarily caused by rockfalls, rockslides, and debris flows. Worldwide, landslides cause thousands of casualties and billions of dollars in damages. 195 Although there are no scales for the intensity or severity of landslides, understanding the likelihood of deep land sliding based on regional estimates of rock strength and steepness of slopes can help understand the extent and intensity of potential landslides. A statewide analysis of landslide susceptibility was conducted by the California Geological Survey using a combination of regional rock strength and slope data to create classes of susceptibility. The methodology used for the analysis assumed, in general, that landslide susceptibility is low on very low slopes in all rock materials, and that susceptibility increases with slope and in weak rocks. The analysis also factored in locations of past landslides. 196

4.6.6.4. Warning Time
Landslides can occur suddenly or slowly. The velocity of mass movement depends on slope angle, material, and water content. Some methods used to monitor mass movements can provide an idea of the type of movement and the amount of time prior to failure. It is also possible to determine what areas are at risk during general time periods. Assessing the geology, vegetation, and amount of predicted 195 United States Geological Survey. (2004). Landslide Types and Processes. Retrieved from https://pubs.usgs.gov/fs/2004/3072/pdf/fs2004-3072.pdf. 196 California Geological Survey. (2011). Susceptibility to Deep-Seated Landslides in California. Retrieved from https://www.conservation.ca.gov/cgs/documents/publications/map-sheets/MS_058.pdf.

5.6.b
Packet Pg. 242 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 170 precipitation for an area can help in these predictions. However, there is no practical warning system for individual landslides.

USGS provides a system of notification for potential landslides, listed in Table 4-118. Watches and warnings may be issued for discrete areas and include advice about contacting the area's local emergency management. Additionally, rainfall induced debris flows watches and warning are weather dependent and will closely track NWS advisories for flash flooding. 197 Table 4-118. USGS Landslide Advisories
Type Description
Landslide Advisory
A general statement about the potential of landslide activity in a given region relative to developing rainfall predictions. An advisory may include general statements about rainfall conditions that can lead to debris flow activity, and list precautions to be taken in the event of heavy rainfall.

Landslide Watch
Means that landslide activity will be possible but is not imminent. People in, or planning to travel through, a watch area should know landslide preparedness and stay informed about developing weather patterns.

Landslide Warning Indicate that landslide activity is presently occurring, and extreme caution should be taken.

4.6.6.5. Probability and Frequency
The probability of occurrence for landslides in Contra Costa County is high because significant occurrences of this hazard are likely to occur annually. Additionally, according to the 2023 California State Hazard Mitigation Plan, landslide probability of occurrence is notably high in the coastal regions of California where much of the State’s population, industry, and infrastructure is located. 198 Probability of Future Hazard Events
The landslide annualized frequency value represents the average number of recorded landslide hazard occurrences in event days, per year over the period of record (11.8 years). Table 4-119 outlines the annualized frequency for landslides, based on FEMA NRI data, for Contra Costa County. While the FEMA NRI has an annual frequency of zero (0) landslide events in the County, studies and landslide data suggest that at least one (1) landslide event will occur every year.

Table 4-119. Landslide Annualized Frequency (FEMA National Risk Index) Location Events on Record
(2010 – 2021) Annualized Frequency
Contra Costa County 12 0.0 events per year
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year.

4.6.6.6. Past Events
In Contra Costa County, landslides have occurred in conjunction with heavy rainfall events. Table 4-120 lists landslide events that affected Contra Costa County between 1980 and 2023. There are no records 197 United States Geological Survey. (n.d.). What is the Difference Between a Landslide Advisory, a Landslide Watch, and a Landslide Warning? Retrieved from https://www.usgs.gov/faqs/what-difference-between-landslideadvisory-landslide-watch-and-landslide-warning. 198 California Governor’s Office of Emergency Services. (2023). California State Hazard Mitigation Plan. Retrieved from https://www.caloes.ca.gov/wp-content/uploads/Hazard-Mitigation/Documents/2023-CaliforniaSHMP_Volume-1_11.10.2023.pdf.

5.6.b
Packet Pg. 243 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 171 in the County of fatalities attributed to landslides. However, deaths have occurred across the west coast as a result of slides and slope collapses.

Table 4-120. Significant Landslide Events
Date Event Type Location Description
December 27, 2022 –
January 31, 2023
Severe storms,
flooding,
landslides, and
mudslides
Contra Costa
County
(43 other counties
in the State)
An atmospheric river impacted the State of
California beginning on December 27, 2022,
producing torrential rainfall which resulted in
catastrophic landslides and mudslides
throughout Contra Costa County.

February 27, 2017 –
March 4, 2017 Mudslide
Near the City of
Concord and
City of
Brentwood
A slow moving mudslide closed the 3100
block of Morgan Territory Road from
Concord to Brentwood and Livermore. It
caused Contra Costa Water District’s
waterline to break, which affected about 90
customers.

January 3, 2017 –
January 12, 2017
Severe storms,
flooding, and
mudslides
Contra Costa
County
(33 other counties
in the State)
Trees and landslides covered roadways
throughout the Bay Area. (DR-4301)
March 13, 2016 Landslide Town of Moraga
A landslide forced two (2) homeowners to
evacuate their homes in the Town of
Moraga. A lower portion of the hill slid into
San Pablo Creek in January.
2011 Winter Storm Local
Central Contra Costa Sanitary District
reported landslides and damage to sewer
pipes.

December 17, 2005 –
January 3, 2006
Severe storms,
flooding,
mudslides, and
landslides
Contra Costa
County
(29 other counties
in the State)
A series of rainfall events caused significant
runoff with localized evacuations, some
slope failures, and road closures throughout
the declared counties. Urban flooding
initiated landslides that contributed to the
damage. In Contra Costa County, much of
the damage was in the following cities –
Walnut Creek, Richmond, San Pablo,
Martinez, and Orinda. Damaged facilities
included schools, park areas, and several
government agency structures. (DR-1628)
February 13, 2000 –
February 14, 2000 Flash Flood Countywide
Widespread rainfall occurred over 24 hours
with accumulations exceeding five (5)
inches. Several homes in Daly City had to
be evacuated due to mudslides and
consecutive years of above average rainfall.

February 2, 1998 –
April 30, 1998
Severe winter
storms and El
Niño rainstorm
San Francisco
Bay Area
Widespread flooding occurred that caused
landslides in Contra Costa County. (DR1203)
December 2, 1996 –
April 1, 1997
Severe storms,
flooding,
mudslides, and
landslides
Contra Costa
County
(46 other counties
in the State)
Minor landslide damage in Contra Costa
County was attributed to heavy rainfall and
saturated soils. (DR-1155)
February 13, 1995 –
April 19, 1995
Severe winter
storms, flooding,
landslides, and
mud flows
San Francisco
Bay Area
Minor landslide damage in Contra Costa
County was attributed to heavy rainfall and
saturated soils. (DR-1046)

5.6.b
Packet Pg. 244 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 172 Date Event Type Location Description
January 3, 1995 –
February 10, 1995
Severe winter
storms, flooding,
landslides, and
mud flows
San Francisco
Bay Area
Minor landslide damage in Contra Costa
County was attributed to heavy rainfall and
saturated soils. (DR-1044)
January 5, 1993 –
March 20, 1993
Severe winter
storm,
mudslides,
landslides, and
flooding
Contra Costa
County
(26 other counties
in the State)
Minor landslide damage in Contra Costa
County was attributed to heavy rainfall and
saturated soils. (DR-979)
January 21, 1983 –
March 30, 1983
Coastal storms,
floods, slides,
and tornadoes
Contra Costa
County
(35 other counties
in the State)
Heavy rainfall throughout coastal areas of
California caused landslides. (DR-677)
December 19, 1981 –
January 8, 1982
Severe storms,
flood, mudslides,
and high tide
San Francisco
Bay Area
Prolonged heavy rainfall and saturated soils
caused numerous slope failures and mud
flows on steep and unstable slopes
throughout the San Francisco Bay area. In
Contra Costa County, 335 homes were
damaged by landslides. (DR-651)
Sources: FEMA 2017; Hazard Mitigation Plan Annual Progress Report, California Geology 1982; USGS 1984, 1987, 1989 and 1998; and NOAA, 2017.

4.6.6.7. Vulnerability and Impacts
Life Safety and Health: In general, all of the population within landslide susceptibility areas are considered to be vulnerable, especially those within a high landslide susceptibility area (Class VIII – X).

As illustrated in Figure 4-16, the majority of the population in the western portion of Contra Costa County is within a high (Class VIII – X) landslide susceptibility area. Increasing population and the fact that many homes are built on property atop or below bluffs and on steep slopes subject to mass movement, increases the number of lives endangered by this hazard.

The underserved and at risk population face unique vulnerabilities and impacts as a result of landslides.

These groups include, but are not limited to, households in poverty, the elderly population, undocumented individuals, and population living in single access roads.199 Household in Poverty: Includes those with an income at or below $24,300 for a household of four (4). This population may live in homes that are less structurally sound. In the event of a landslide, the foundation of these homes can be damaged or completely destroyed resulting in financial strain for these households. In Contra Costa County, a high concentration of households in poverty within high landslide susceptibility areas can be found in Rodeo, Crockett, Bay Point, and Port Costa.

Senior (65 years old and over): The elderly population (i.e., seniors), especially those with access and functional needs, may have physical limitations that make it harder to evacuate in the event of an emergency, such as flooding. Furthermore, the elderly population may lack access to social connections and community support that can assist in preparing for and responding to emergency events, evacuating, improving home resiliency, managing medical needs, and 199 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.

5.6.b
Packet Pg. 245 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 173 locating support services. Communities with high concentrations of seniors are primarily located on the hillsides in Contra Costa County, which are within high landslide susceptibility areas.

Undocumented Individuals: Includes people who do not have formal permission to live in the United States (i.e., do not have citizenship, permanent residency, visas, or other similar status).

This population is most likely to fall in the households in poverty and low income categories, which are considered to be at risk populations during a landslide event.

In Contra Costa County, several neighborhoods and communities in the Delta and in the hillside areas of central and western Contra Costa County are only accessible via one roadway.

Table 4-121 summarizes the vulnerable and at-risk population for landslides in Contra Costa County.

Table 4-121. Vulnerability and At Risk Population
Category Estimate Percent
Households in Poverty200 7,600 12.0%
65 Years and Over201 201,136 17.4%
Seniors (65 years and over) Living
Alone202 45,672 22.7%
Undocumented Individuals203 There are no official counts of how many undocumented individuals live in Contra Costa County, but in 2019 there was an estimate of 63,000.

Table 4-126 outlines the vulnerability of the total population exposed to landslides, and Table 4-127 outlines the landslide impacts to population and life safety, underserved/equity population, and essential operations, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Property Damage and Critical Infrastructure: Although only a partial list of historical landslides in Contra Costa County is available, the available records suggest a significant vulnerability to this hazard.

The millions of dollars in damage Countywide attributable to mass movement during those events affected private property and public infrastructure and facilities. Loss estimations for the landslide hazard are not based on modeling utilizing damage functions, because no such damage functions have been generated. Instead, loss estimates were developed representing 10%, 30%, and 50% of the replacement value of exposed structures. This allows emergency managers to select a range of economic impact based on an estimate of the percentage of damage to the general building stock. Damage in excess of 50% is considered to be substantial by most building codes and typically requires total reconstruction of the structure.
200 Ibid.
201 United States Census Bureau. (2022). DP05: Demographics and Housing Estimates (2022: ACS 1-Year Estimates Data Profiles). Retrieved from
https://data.census.gov/table/ACSDP1Y2022.DP05?g=050XX00US06013. 202 United States Census Bureau. (2022). DP02: Selected Social Characteristics in the United States (2022: ACS 1-Year Estimates Data Profiles). Retrieved from
https://data.census.gov/table/ACSDP1Y2022.DP02?g=050XX00US06013. 203 Migration Policy Institute. (2019). Profile of the Unauthorized Population: Contra Costa County, CA. Retrieved from https://www.migrationpolicy.org/data/unauthorized-immigrant-population/county/6013.

5.6.b
Packet Pg. 246 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 174 In Contra Costa County, there is a range from the large, state-owned bridges that carry interstate freeways, to locally owned bridges that carry rural roads and pedestrians over small creeks. Countywide, there are over 400 bridges where approximately 80 are owned by the County and 160 are owned by Caltrans. Landslides can cause severe damage to bridges which can cause them to become unstable and fail. State Route 4 and 24, Interstate 80 and 680, and 40 bridges are located within moderate to very high landslide susceptibility areas in Contra Costa County. Disruption to the fourth bore of the Caldecott Tunnel can substantially disrupt regional transportation and connections between the County and the rest of the Bay Area. Also, the following transportation assets are within moderate and high landslide susceptibility zones – North Concord/Martinez BART station, Martinez Amtrak station, Pittsburg/Bay Point BART station, and Lafayette BART station. A landslide disruption (e.g., damage to tracks or station) could limit transit opportunities within east and west County.

Electrical transmission and distribution lines are power lines that carry high voltage electricity between power plants and customers. There are a number of transmission lines throughout the County and a number pass over hills and mountains within high landslide susceptibility areas in the eastern and western portion of the County. The electric infrastructure is extremely vulnerable to landslides as they can be damaged or destroyed. Also, these power lines are used to distribute electricity to other regions in the Bay Area, so, if multiple lines are disrupted due to a landslide it can cause widespread power outages.

Additionally, there are approximately 34 industrial structures within landslide prone areas within the County. In the event a landslide impacts these structures, holding tanks can be disturbed resulting in a chemical release and contamination of surrounding areas.204 There are a total of 554 critical assets (i.e., schools, nursing homes, fire stations, police stations, and hospitals) throughout the County and 306 (55.2%) are located within a landslide susceptibility area. Table 4-43 provides a breakdown of critical assets that are located within a landslide susceptibility area in Contra Costa County.

Table 4-122. Critical Assets Vulnerable to Landslides
Asset Estimate Percent
(of total asset)
Schools (public schools, private schools) 173 48.1%
Nursing Homes 51 65.4%
Fire Stations 57 70.4%
Police Stations 17 70.8%
Hospitals 8 72.7%
Table 4-126 outlines the total property value exposed to landslides and how the changes in development in the past five (5) years have affected the vulnerability of the community to landslides. Table 4-127 outlines the landslide impacts on total property damage, potential future development, and the economy, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Environment: A landslide alters the landscape of an area. In addition to changes in topography, vegetation and wildlife habitats may be damaged or destroyed. Soil and sediment runoff will accumulate downslope, potentially blocking waterways and roadways and impairing the quality of streams and other 204 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.

5.6.b
Packet Pg. 247 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 175 water bodies. Furthermore, landslides that fall into streams may impact fish and wildlife habitat, as well as affect water quality. Hillsides that provide wildlife habitat can be lost for prolonged periods. In central and western Contra Costa County, some aquatic habitats (i.e., streams, reservoirs, ponds, and sloughs or channels) are located within landslide prone areas. Streams can be blocked by a landslide which significantly affects fish and wildlife habitat because of additional debris that is being added into the habitat. Aquatic ecosystems in the County include the Delta and shoreline areas that are submerged by water, and the three (3) large reservoirs – San Pablo Reservoir, Briones Reservoir, and Los Vaqueros Reservoir. Aquatic wildlife species include various duck species, California red-legged frog, western pond turtle, and juvenile and spawning adult Chinook salmon.205 Table 4-127 outlines landslide impacts on the environment and economy, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Changes in Development and Impact of Future Development: Changes in development have not significantly affected the risk from landslides and future development should have minimal impact on risk associated with landslides. Contra Costa County has implemented stricter zoning and building codes and policies for areas that are prone to landslides. For example, projects in areas of known landslide susceptibility require submittal of a geotechnical report and the County ensures effective mitigation measures are incorporated into the project’s design. The implementation of these policies will ensure that future development trends minimally increase impact/consequence of landslides within Contra Costa County.

Table 4-126 outlines how the changes in development in the past five (5) years have affected the vulnerability of the community to landslides. Table 4-127 outlines the landslide impacts on potential future development, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Effects of Climate Change in Severity of Impacts: Climate change does not directly cause more frequent or intense landslides. However, it is expected to increase the conditions that can lead to landslides, such as an increase in heavy storms that saturate the ground and make a landslide more likely. As global average temperatures increase; evaporation increases adding moisture into the atmosphere which results in more precipitation.206 The frequency and intensity of heavy precipitation events are projected to increase over the 21st century.207 Although heavy precipitation does not necessarily result in landslides, landslides are predominantly a result of saturated soils, it is possible that increased intensity of rain events will result in a greater number of landslides annually and an increase in the severity of impacts. Increasing temperatures are expected to increase the occurrence and duration of droughts and the probability of wildfire, reducing the vegetation that helps to support slopes and slows down water. Overall, the impacts of climate change on drought, heavy rainfall, and wildfire will result in an increased probability for landslide occurrences. Table 4-123 indicates the 25-year climate projections in Contra Costa County.
205 Ibid.
206 Environmental Protection Agency. (n.d.). Climate Change Indicators: U.S. and Global Precipitation. Retrieved from https://www.epa.gov/climate-indicators/climate-change-indicators-us-and-global-precipitation. 207 U.S. Global Change Research Program. (2017). Climate Science Special Report: Fourth National Climate Assessment, Volume I (Chapter 7: Precipitation Change in the United States). Retrieved from https://science2017.globalchange.gov/chapter/7/.

5.6.b
Packet Pg. 248 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 176 Table 4-123. 25-Year Climate Projections for Contra Costa County 208 Higher Emissions (RCP8.5)
Contra Costa County is expected to experience a 43% increase in extremely hot days and a 7% increase in days with heavy precipitation within 25 years.

By 2048, Contra Costa County is expected to have a 0.4 inches increase (from 19.6 inches to 20.1 inches) in average annual precipitation.

By 2049, Contra Costa County is expected to experience 11 more days that reach above 95°F (from 23 days to 33 days per year).

Lower Emissions (RCP4.5)
Contra Costa County is expected to experience a 29% increase in extremely hot days and an 8% increase in days with heavy precipitation within 25 years.

By 2048, Contra Costa County is expected to have a 0.15 inches increase (from 19.11 inches to 19.26 inches) in average annual precipitation.

By 2049, Contra Costa County is expected to experience seven (7) more days that reach above 95°F (from 22 days to 29 days per year).

Table 4-127 outlines the climate change impacts to landslides in Contra Costa County, as outlined in the risk assessment methodology in Section 4.3 of this Plan. 208 Northeast Regional Climate Center. (n.d.). Neighborhoods at Risk: Climate Projections. Retrieved from https://nar.headwaterseconomics.org/.

5.6.b
Packet Pg. 249 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Landslide High Significant hazard event is likely to occur annually. 3 N/A Landslide
Extent/Intensity Medium Historical and/or probabilistic models/studies for this hazard indicate the possibility of a medium-intensity incident. 2 6Catastrophic Low Catastrophic hazard event is likely to occur at least once in 51 or more years. 1 3 Landslide
Population Exposure Low 14% or less of the population is exposed to the hazard. 1 3Property Exposure Low 9% or less of the total assessed property value is exposed to a hazard. 1 2Changes inDevelopment Low Changes in development have increased thevulnerability/exposure of the community to the hazard by 4%or less. 1 1 Landslide
Population and LifeSafety Medium
Populations exposed to this hazard are likely to experiencesome adverse impacts, such as injuries requiring acutemedical care. 2 6 Underserved/Equity Low
Underserved populations exposed to the hazard are likely toexperience minimal adverse/disproportionate impacts, suchas ambulatory injuries. 1 3 Property Damage High
More than $5 Million in property damages is expected from asingle major hazard event, or damages are expected to occurto 15% or more of the property value within the jurisdiction. 3 6 Economic Low Total economic impact is not likely to be greater than $100,000. 1 1

5.6.b
Packet Pg. 250 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Environmental Low
Environmental impact from a single major hazard event islikely to be minimal, requiring little to no outside resourcesand support, and/or minimal repair, clean-up, restoration, orpreservation work. 1 1
Essential Operations Medium
Impact between 24 and 72 hours on the ability of thejurisdiction to meet the essential day-to-day operationaldemands and needs of the community from a single majorhazard event. 2 2
Future Development Low Future development trends will minimally increase impact/consequence of this hazard. 1 1Climate Change Medium Climate Change trends will increase the risk of this hazard and its impacts, but not significantly. 2 2

5.6.b
Packet Pg. 251 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 179

4.6.6.8. FEMA NRI Expected Annual Loss Estimates
A landslide NRI EAL score, and rating represent a community's relative level of expected building and population loss each year due to landslides when compared to the rest of the United States. The EAL score is positively associated to a community’s risk; therefore, a higher EAL score results in a higher Risk Index score. Table 4-128 outlines the landslide EAL for Contra Costa County.

Table 4-128. Landslide Expected Annual Loss (FEMA National Risk Index) Jurisdiction Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual
Loss
Expected
Annual
Loss
Score
Rating
Contra Costa
County $25,121 $207,224 n/a $232,345 94.6 Very High
Expected annual loss scores are calculated utilizing an equation that combines values for exposure, annualized frequency, and historic loss ratios (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio).

4.6.6.9. FEMA Landslide Risk Index Scores
The landslide Risk Index score and rating represent a community's relative risk for landslide when compared to the rest of the United States. Table 4-129 illustrates the landslide Risk Index rating and score for Contra Costa County.

Table 4-129. Landslide Risk Index (FEMA National Risk Index) Jurisdiction Rating Score
Contra Costa County Very High 93.7
Risk Index scores are calculated using an equation that combines scores for Expected Annual Loss due to natural hazards, Social Vulnerability and Community Resilience (Expected Annual Loss x Social Vulnerability / Community Resilience = Risk Index).

5.6.b
Packet Pg. 252 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 180 Table 4-130 represents the Landslide Total Risk Score for Contra Costa County, based on the Risk Assessment Methodology, as defined in this Plan. For further details on how the probability, extent, vulnerability, and impact factors were calculated, please refer to Table 4-124 through Table 4-127.

Additional details on how the Total Risk Score was calculated can be found in the Risk Assessment Methodology in Section 4.3 of this Plan.

Table 4-130. Landslide Total Risk Score
Hazard
Event
Probability Consequence Total Risk
Probability
Factor Extent Vulnerability Impact ConsequenceScore
Total Risk
Score*
Landslide 3 9 6 22 37 55
Consequence: Sum of all weighted factors.

Extent: Sum of the weighted Extent factors.

Vulnerability: Sum of the weighted Vulnerability factors.

Impact: Sum of the weighted Impact factors.

The Total Risk Score is a measure of Probability and Consequence.

5.6.b
Packet Pg. 253 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 181

4.6.7. Sea Level Rise

4.6.7.1. Description
Sea level rise is the increase in the global mean sea level to the effects of climate change, a trend that is expected to continue. 209 Sea level has a significant role in flooding, coastal erosion, and storm hazards (e.g., coastal flooding).

Increasing global surface temperatures, melting glaciers and ice sheets, and thermal expansion are climate conditions causing sea level to rise globally. However, there are additional factors affecting global sea level change – subsidence and uplift. Vertical land motion (VLM) includes both subsidence and uplift and changes can add up over time. Subsidence may cause a relative rise in local sea levels, but this is highly dependent on localized factors. Likewise, uplift (the opposite of subsidence) may reduce sea level rise. Both instances of land fluctuation occur, on average, to the degree of a few millimeters per year. 210 Regardless of the cause of sea level rise, a higher average sea level means that hazards such as coastal flooding, flooding, and coastal erosion will have more severe impacts to the population, property, and infrastructure. 211
Sea level rise varies regionally along the United States coasts because of land and ocean height variations. In the next three (3) decades sea level rise is anticipated to be, on average, four (4) to eight (8) inches in western United States. Additionally, sea level rise is expected to create a profound shift in coastal flooding in the next 30 years by causing tide and storm surge heights to increase and move further inland. By 2050, damaging flooding is expected to occur, on average, 10 times more often than it does currently, and it can be intensified by other local factors. 212 Currently, the rate of sea level rise in the San Francisco Bay area roughly matches the global average and expected to be higher than the global average based on half of NOAA’s average sea level rise scenarios. 213 Other sea level rise consequences include: 214
Contra Costa County’s extensive coastal infrastructure (e.g., critical facilities, transportation networks, residential areas) vulnerability to inundation, erosion, and flooding will increase.

High water levels will become more frequent, increasing in extent, depth, and duration of temporary flooding, and expanding the area that is permanently inundated. Impacts will go beyond the coastal area.
209 National Geographic. (n.d.). Sea Level Rise. Retrieved from https://education.nationalgeographic.org/resource/sea-level-rise/. 210 National Aeronautics and Space Administration, Sea Level Change. (n.d.). Understanding Sea Level.

Retrieved from https://sealevel.nasa.gov/understanding-sea-level/regional-sea-level/subsidence. 211 National Oceanic and Atmospheric Administration, Climate.gov. (2022). Climate Change: Global Sea Level.

Retrieved from https://www.climate.gov/news-features/understanding-climate/climate-change-global-sea-level. 212 National Oceanic and Atmospheric Administration, National Ocean Service. (2022). 2022 Sea Level Rise Technical Report. Retrieved from https://oceanservice.noaa.gov/hazards/sealevelrise/sealevelrise-techreport.html. 213 San Francisco Baykeeper. (n.d.). Sea Level Rise Long California: Questions and Answers. Retrieved from https://baykeeper.org/shoreview/california-slr.html.
214 Contra Costa County Adapting to Rising Tides Project. (2017). Adapting to Rising Tides: Contra Costa County Assessment and Adaptation Project. Retrieved from https://www.adaptingtorisingtides.org/wpcontent/uploads/2017/03/Contra-Costa-ART-Project-Report_Final.pdf.

5.6.b
Packet Pg. 254 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 182 The hazard poses substantial economic risks, as it threatens businesses, port facilities, and industries reliant on the San Francisco Bay area waterways, potentially resulting in loss of revenue, jobs, and decreased property values.

Sea level rise can lead to the loss of critical coastal habitats, increased salinity in estuaries, and harm to native species, impacting the region's ecological balance.

4.6.7.2. Hazard Location
All coastal communities in the County are vulnerable to sea level rise. Areas with low lying shorelines such as the City of Richmond and the City of Concord are particularly at risk. Additionally, the extensive coastline along San Pablo and Suisun Bays, including unincorporated County and coastal cities – El Cerrito, San Pablo, Pinole, Hercules, Rodeo, Pittsburg, Antioch, and Martinez. Figures 4-17 and 4-18 depicts the Contra Costa County 2050 and 2100 sea level rise projections, respectively. 215
Figure 4-17. Expected Sea Level Rise 2050 Projection
215 Contra Costa County. (2023). Public Review Draft Contra Costa County 2045 General Plan – Health and Safety Element. Retrieved from https://envisioncontracosta2040.org/wpcontent/uploads/2024/02/Chapter_9_Health-and-Safety-Element.pdf.

5.6.b
Packet Pg. 255 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 183 Figure 4-18. Expected Sea Level Rise 2100 Projection

4.6.7.3. Hazard Extent/Intensity
There are no intensity scales for measuring sea level rise. In 2018, the State of California updated the sea level rise projections for San Francisco, based on greenhouse gasses emissions scenarios used by the IPCC in the Fifth Assessment Report, called the Representative Concentration Pathways (RCP). The high emissions represent the RCP 8.5 scenario, and the low emissions represent the RCP 2.6 scenario.

Table 4-131 illustrate the recommended probabilistic projections for the height of sea level rise in the San Francisco area, as see in the Rising Seas Report. 216 Table 4-131. Projected Sea Level Rise for San Francisco Emissions Scenario Year
Likely Range
(feet)
66% probability sea level
rise is between…
1 in 200 Chance
(feet)

0.5% probability sea level
rise meets or exceeds…
High Emissions 2030 0.3 – 0.5 0.8
High Emissions 2040 0.5 – 0.8 1.3
High Emissions 2050 0.6 – 1.1 1.9
Low Emissions
2060

0.6 – 1.3 2.4
High Emissions 0.8 – 1.5 2.6
216 California Natural Resources Agency. (2018). State of California Sea level Rise Guidance (2018 Update).

Retrieved from https://www.opc.ca.gov/webmaster/ftp/pdf/agenda_items/20180314/Item3_ExhibitA_OPC_SLR_Guidance-rd3.pdf.

5.6.b
Packet Pg. 256 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 184 Emissions Scenario Year
Likely Range
(feet)
66% probability sea level
rise is between…
1 in 200 Chance
(feet)

0.5% probability sea level
rise meets or exceeds…
Low Emissions
2070

0.8 – 1.5 3.1
High Emissions 1.0 – 1.9 3.5
Low Emissions
2080

0.9 – 1.8 3.9
High Emissions 1.2 – 2.4 4.5
Low Emissions
2090

1.0 – 2.1 4.7
High Emissions 1.4 – 2.9 5.6
Low Emissions
2100

1.0 – 2.4 5.7
High Emissions 1.6 – 3.4 6.9
Low Emissions
2110*

1.2 – 2.5 6.3
High Emissions 1.9 – 3.5 7.3
Low Emissions
2120

1.2 – 2.8 7.4
High Emissions 2.2 – 4.1 8.6
Low Emissions
2130

1.3 – 3.1 8.5
High Emissions 2.4 – 4.6 10.0
Low Emissions
2140

1.3 – 3.4 9.7
High Emissions 2.6 – 5.2 11.4
Low Emissions
2150

1.3 – 3.8 11.0
High Emissions 2.8 – 5.8 13.0
Most of the available climate model experiments do not extend beyond 2100. The resulting reduction in model availability causes a small dip in projections between 2100 and 2110, as well as a shift in uncertainty estimates (see Kopp et al. 2014).

Use of 2110 projections should be done with caution and with acknowledgement of increased uncertainty around these projections.

4.6.7.4. Warning Time
There is no warning time mechanism for sea level rise. However, probabilistic projections for sea level rise over various timescales have been developed. These projections are meant to help decision makers to better understand future sea level rise and when a particular level is expected to occur.

4.6.7.5. Probability and Frequency
The probability of occurrence for sea level rise in Contra Costa County is medium because along the Contra Costa County shoreline, sea levels are projected to rise up to about 2 feet (24 inches) by 2050 and 7 feet (84 inches) by 2100. However, it is possible that sea levels could rise faster than these projections, which has happened historically.

Probability of Future Hazard Events
The State of California Sea Level Rise Guidance 2018 update provides the probability of sea level rise meeting or exceeding a particular height for each decade between 2030 and 2150. The probability that sea level rise will meet or exceed a particular height in San Francisco for high emissions (RCP 8.5) is

5.6.b
Packet Pg. 257 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 185 listed on Table 4-132 and low emissions (RCP 2.6) is listed on Table 4-133. The areas shaded in gray have less than a 0.1% probability of occurrence. 217
Table 4-132. Probability that Sea level Rise Will Meet or Exceed a Particular Height in San Francisco (High Emissions – RCP 8.5)
1 Feet 2 Feet 3 Feet 4 Feet 5 Feet 6 Feet 7 Feet 8 Feet 9 Feet 10 Feet 2030 0.1%
2040 3.3%
2050 31% 0.4%
2060 65% 3% 0.2% 0.1%
2070 84% 13% 1.2% 0.2% 0.1%
2080 93% 34% 5% 0.9% 0.3% 0.1% 0.1%
2090 96% 55% 14% 3% 0.9% 0.3% 0.2% 0.1% 0.1%
2100 96% 70% 28% 8% 3% 1% 0.5% 0.3% 0.2% 0.1%
2150 100% 96% 79% 52% 28% 15% 8% 4% 3% 2%
Table 4-133. Probability that Sea level Rise Will Meet or Exceed a Particular Height in San Francisco (Low Emissions – RCP 2.6)
1 Feet 2 Feet 3 Feet 4 Feet 5 Feet 6 Feet 7 Feet 8 Feet 9 Feet 10 Feet 2060 43% 1.4% 0.2%
2070 62% 4% 0.6% 0.2% 0%
2080 74% 11% 2% 0.4% 0.2% 0.1%
2090 80% 20% 3% 1.0% 0.4% 0.2% 0.1% 0.1%
2100 84% 31% 7% 2% 0.8% 0.4% 0.2% 0.1% 0.1%
2150 93% 62% 31% 14% 7% 4% 2% 2% 1% 1%
The FEMA NRI analyses coastal flooding – when water inundates or covers normally dry coastal land as a result of high or rising tides or storm surges.
218 The coastal flooding annualized frequency value
represents the modeled frequency of coastal flooding occurrences, in events per year. Table 4-134 outlines the annualized frequency for coastal flooding, based on FEMA NRI data, for Contra Costa County.

Table 4-134. Coastal Flooding Annualized Frequency (FEMA National Risk Index) Location Events on Record Annualized Frequency
Contra Costa County n/a 1.5 events per year
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year. 217 Ibid.
218 Federal Emergency Management Agency. (n.d.). FEMA National Risk Index: Coastal Flooding. Retrieved from https://hazards.fema.gov/nri/coastal-flooding.

5.6.b
Packet Pg. 258 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 186

4.6.7.6. Past Events
Changes in sea level have been occurring for at least the last 100 years and are projected to continue.

The rate of sea level rise is increasing, and this trend is projected to continue.

4.6.7.7. Vulnerability and Impacts
Life Safety and Health: The population in areas with low lying shorelines (e.g., City of Richmond, City of Concord) are particularly at risk. Additionally, the extensive coastline along San Pablo and Suisun Bays, including unincorporated County and coastal cities – El Cerrito, San Pablo, Pinole, Hercules, Rodeo, Pittsburg, Antioch, and Martinez.

The underserved and at risk population face unique vulnerabilities and impacts as a result of sea level rise. These groups include, but are not limited to, households in poverty, individuals experiencing homelessness, and the population living on single access roads.

Household in Poverty: Includes those with an income at or below $24,300 for a household of four (4). This population is most likely to live in low lying areas and the structures may not be waterproofed or built above the 100-year flood elevation. In Contra Costa County, the households in poverty within Vine Hill, Bay Point, and North Richmond are vulnerable to sea level rise.

Individuals Experiencing Homelessness: Includes those who do not have a permanent home, including those who live in their vehicles or temporary shelters. This population is uniquely vulnerable to sea level rise because most of the homeless encampments are located along the coastal cities near and within coastal flood areas in the County. Therefore, sea level rise can damage or destroy these encampments and other homeless facilities located within the coastline resulting in additional hardship for this population. In 2024, there are 2,843 people experiencing homelessness in Contra Costa County, an 18.5% increase from 2023. 219
Individuals Living on Single Access Roads: Includes those living in areas with a single route in and out (i.e., accessible via one (1) roadway) of the neighborhood or area (e.g., Rodeo, Crockett, and Port Costa). This includes several communities in the Delta and in the hillside areas of central and western Contra Costa County. This population is uniquely vulnerable to sea level rise because as sea level continues to rise, these roadways may become permanently impassible.

These communities can become isolated from the community and emergency services in the long term. As illustrated in Figure 4-18, sea level rise is projected to significantly impact the Delta islands located in the eastern section of the County by 2100.220 Table 4-135 summarizes the vulnerable and at-risk population for sea level rise in Contra Costa County.

Table 4-135. Vulnerability and At Risk Population
Category Estimate Percent
Households in Poverty221 7,600 12.0%
219 Contra Costa Health. (2024). Health, Housing, and Homelessness Data Reports (Point-in-Time Count).

Retrieved from https://www.cchealth.org/services-and-programs/homeless-services/data. 220 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.
221 Ibid.

5.6.b
Packet Pg. 259 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 187 Category Estimate Percent
Low Income Households222 25,340 41.0%
Homeless Population223 2,372 0.2%
Table 4-139 outlines the vulnerability of the total population exposed to sea level rise, and Table 4-140 outlines the sea level rise impacts to population and life safety, underserved/equity population, and essential operations, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Property Damage and Critical Infrastructure: As sea level continues to rise, repeated disruptions by coastal flooding will aggravate existing impacts on infrastructure, initiate cascading impacts on the larger economy, and burden people. Saltwater intrusion into drinking water sources can result in the need for water utilities to increase treatment, relocate water intakes, or develop alternate sources of fresh water.

Saltwater intrusion, through surface water or groundwater sources, may diminish the availability or quality of source waters for drinking water utilities.

In Contra Costa County, the levees near North Richmond, Vine Hill, and the Delta can be damaged or overtopped due to an increase in coastal storm events and sea level rise is exacerbating the effects of these events. Interstate 80 and 680, and State Route 160 are within sea level rise inundation areas.

Flooding to these roadways and other local roadways can cause major disruptions to local and regional transportation, transit, and commuters.

The BART, Amtrak, and the freight lines are located within the flood areas in coastal and northern Contra Costa County. There are three (3) standard rail lines that run through the County which are operated by Union Pacific, Burlington Northern Santa Fe, and Richmond Pacific Railroad Corporation. These run along the western, northern, and eastern boundaries of the County, along Interstate 80, State Route 4, and Byron Highway. The aforementioned rail lines are used for freight trains; however, the Capitol Corridor commuter train runs along the Union Pacific railway. Additionally, the BART operates its own separate rail lines used exclusively for public transit. Two (2) BART rail lines are located in the County – one beginning in Richmond and heading south toward Berkeley and another one in the central part of the County extending from the City of Orinda to the City of Antioch. Furthermore, some of these rail lines serve as the first line of defense against coastal flooding for communities; these rail lines include Martinez and Antioch Amtrak stations, rail lines along Bay Point, Montalvin Manor, Rodeo, and Port Costa.

The Rodeo sewage treatment plant, West Contra Costa Wastewater, and the Mt. View Sanitary District are within low lying areas along the coastline. Wet weather flows into the treatment plants can be exacerbated with rising sea levels, preventing the system from functioning properly. Treatment plants can also fail if pumps and control panels are not waterproofed or are not salt-resistant. The Contra Costa Canal and Clifton Court Forebay are also within the coastal flooding area. These water and wastewater infrastructure systems are vulnerable to flooding and shoreline flooding which can be exacerbated by sea level rise. Also, there are approximately 44 industrial buildings in Contra Costa County that are located within sea level rise inundation areas. Most industrial and manufacturing centers, important economic drivers to the County, are located within sea level rise inundation areas along the bayfront and Delta in the western and northern portions of Contra Costa County. These center can be damaged by floods 222 Ibid.
223 Contra Costa Health. (2023). Health, Housing, and Homelessness Data Reports (Point-in-Time Count).

Retrieved from https://www.cchealth.org/services-and-programs/homeless-services/data.

5.6.b
Packet Pg. 260 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 188 which could be exacerbated by sea level rise. These centers are located in the neighborhoods of North Richmond, Rodeo, Crockett, Bay Point, Pacheco, Clyde, and the City of Martinez.224 There are a total of 554 critical assets (i.e., schools, nursing homes, fire stations, police stations, and hospitals) throughout the County and none are located within inundation areas for one (1) foot of sea level rise. Table 4-43 provides a breakdown of critical assets that are located within sea level rise inundation areas for one (1) foot in Contra Costa County.

Table 4-136. Critical Assets in Vulnerable to 1 Foot of Sea Level Rise Asset Estimate Percent
(of total asset)
Schools (public schools, private schools) 0 0.0%
Nursing Homes 0 0.0%
Fire Stations 0 0.0%
Police Stations 0 0.0%
Hospitals 0 0.0%
Table 4-139 outlines the vulnerability of the total property value exposed to a flood event, and the impact on total property damage in the event of a flood, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Environmental: Rising seas increase the risk of flooding, storm surge inundation, erosion and shoreline retreat, and wetland loss. Rising sea levels also threaten a significant portion of prime agricultural land in the County, as low lying areas could be subject to more frequent shoreline flooding and saltwater intrusion into groundwater basins could disrupt agricultural water supplies. Meanwhile, rising tides may increase groundwater levels, inundating contaminated soil and pushing toxins toward the surface. Given that some contaminated sites in Contra Costa County are located near the shoreline, rising groundwater may cause contaminated soil to leach into previously unaffected areas. Natural ecosystems in the Bay and Delta regions will be disrupted by the higher tide levels and intrusion of saltwater into freshwater systems. Historically, marshes have adapted to changes in sea level by building up sediment, increasing the height of the marsh to keep pace with the tide levels of San Francisco Bay, and by moving inland.

However, sea level rise is expected to outpace the rate of marsh-level rise and development near wetlands will likely prevent marsh migration. Without substantial intervention, most tidal marshes in Contra Costa County are expected to convert to another habitat type, a process called “downshifting,” which will lead to the establishment of different plant and animal species. Additionally, sea level rise may push saltwater into the Delta’s aquatic system which will decrease the water quality and harm aquatic species and organisms.

Some of the environmental assets that are vulnerable and can be impacted by sea level rise within the County are considered major economic drivers. Significant impacts to these assets can result in economic challenges to Contra Costa County and disruptions to these resources can impact the economy of populations that rely on these activities.
225
224 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.
225 Ibid.

5.6.b
Packet Pg. 261 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 189 Agriculture: Agriculture land in the eastern and Delta portions of the County are within sea level rise inundation areas and can face significant economic challenges if agriculture is not viable. Sea level rise can inundate farmland increasing the salinity in the water and soil damaging crops that do not grow in high salt conditions. Furthermore, sea level rise can cause saltwater intrusion which can decrease the water supplies for crop irrigation.

Regional Parks: Regional shorelines and parks on the Bay and Delta could be permanently inundated due to sea level rise resulting in unusable parks which may not meet the demands of the public.

The Delta: The Sacramento-San Joaquin River Delta spans from the City of Pittsburg in the west, Locke in the east, Sacramento to the North, and Tracy to the south. The Delta primarily encompasses the northern and easternmost borders of Contra Costa County and provides opportunities for boating, fishing, transportation, and a water source for the County. Sea level rise can continually or permanently inundate marinas, harbors, farmland, and other recreational facilities within the Delta. Furthermore, saltwater intrusion can disrupt water quality and fish/wildlife population.

Table 4-140 outlines sea level rise impacts on the environment and economy, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Changes in Development and Impact of Future Development: There have been no significant changes in development that have affected the risks associated with sea level rise. Future increases in population within the sea level inundation area and coastal communities will increase vulnerability and impacts to sea level rise. Growth over the past decade has considerably increased. Between 2010 and 2022, as outlined in Table 3-3, the population in Contra Costa County grew 10.6%, from 1,046,025 to 1,156,966 residents. The Bay Area Association of Governments (ABAG) growth forecasts predict a steady increase in households through 2050. From 2015 to 2050, ABAG projects that the County’s number of households will grow by 44%.226 As sea level continues to rise, floodplain boundaries may expand further inland exposing areas that are not currently vulnerable to sea level rise. Additionally, the communities in Contra Costa County that are protected by levees may become more vulnerable because the levee will become increasingly vulnerable to overtopping due to increasing sea level.

Table 4-139 outlines how the changes in development in the past five (5) years have affected the vulnerability of the community to sea level rise. Table 4-140 outlines the sea level rise impacts on potential future development, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Effects of Climate Change in Severity of Impacts: The primary reasons for sea level rise are the added water from ice sheets and glaciers and the ocean water’s thermal expansion, both of which are a result of increasing global average temperatures. 227 Since 1880, the global average sea level has risen between eight (8) to nine (9) inches and in 2022 the average sea level was four (4) inches above 1993 levels, a record high. Due to land processes (e.g., erosion, oil and groundwater pumping, subsidence), the rate of local sea level rise along the United States coastline is greater than the global average.

Furthermore, high tide flooding between 300% and 900% more frequent than 50 years ago. 228 226 Bay Area Association of Government. (2020). Plan Bay Area 2050 Final Blueprint Growth Pattern. Retrieved from https://planbayarea.org/digital-library/plan-bay-area-2050-final-blueprint-growth-pattern. 227 National Aeronautics and Space Administration. (2023). Sea Level. Retrieved from https://climate.nasa.gov/vital-signs/sea-level/.
228 Lindsey, R. (2022). Climate Change: Global Sea Level. Retrieved from https://www.climate.gov/newsfeatures/understanding-climate/climate-change-global-sea-level.

5.6.b
Packet Pg. 262 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 190 In California, observations of climate have shown that sea level rise is expected to continue to increase flooding and erosion of beaches, bluffs, and cliffs. Relative to the average sea levels between 1991 and 2009, sea levels in California may increase in most places by six (6) to 10 inches by 2030, 13 to 23 inches by 2050, and 41 to 83 inches by 2100. However, it is possible that sea level may increase faster than these projections. Studies show that eventually, sea levels may increase enough to permanently inundate low lying areas near the Bay shoreline and the Delta areas.229 Table 4-140 outlines the climate change impacts to sea level rise in Contra Costa County, as outlined in the risk assessment methodology in Section 4.3 of this Plan. 229 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.

5.6.b
Packet Pg. 263 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Sea Level Rise Medium Significant hazard event is likely to occur within 25 years. 2 N/A Sea Level Rise
Extent/Intensity Medium Historical and/or probabilistic models/studies for this hazard indicate the possibility of a medium-intensity incident. 2 6Catastrophic Medium Catastrophic hazard event is likely to occur at least once between 11 and 50 years. 2 6 Sea Level Rise
Population Exposure Low 14% or less of the population is exposed to the hazard. 1 3Property Exposure Low 9% or less of the total assessed property value is exposed to a hazard. 1 2Changes inDevelopment Low Changes in development have increased thevulnerability/exposure of the community to the hazard by 4%or less. 1 1 Sea Level Rise
Population and LifeSafety No Impact Populations exposed to this hazard are not likely to experience significant adverse impacts. 0 0Underserved/Equity Low Underserved populations exposed to the hazard are likely toexperience minimal adverse/disproportionate impacts, suchas ambulatory injuries. 1 3 Property Damage Medium
More than $500,000 but less than $5 Million in propertydamages is expected from a single major hazard event, ordamages are expected to occur to more than 5% but lessthan 15% of the property value within the jurisdiction. 2 4 Economic Medium Total economic impact is likely to be greater than $500,000, but less than or equal to $10 Million. 2 2

5.6.b
Packet Pg. 264 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Environmental Medium
Environmental impact from a single major hazard event islikely to be localized, requiring some outside resources andsupport; and/or repair, clean-up, restoration, or preservationwork. 2 2
Essential Operations Low
Impact less than 24 hours on the ability of the jurisdiction tomeet the essential day-to-day operational demands andneeds of the community from a single major hazard event. 1 1
Future Development Medium Future development trends will increase the impact/consequence of this hazard, but not significantly. 2 2Climate Change High Climate Change trends will significantly increase the risk of this hazard and its impacts. 3 3

5.6.b
Packet Pg. 265 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 193

4.6.7.8. FEMA NRI Expected Annual Loss Estimates
A coastal flooding NRI EAL score, and rating represent a community's relative level of expected building and population loss each year due to coastal flooding when compared to the rest of the United States.

The EAL score is positively associated to a community’s risk; therefore, a higher EAL score results in a higher Risk Index score. Table 4-141 outlines the coastal flooding EAL for Contra Costa County.

Table 4-141. Coastal Flooding Expected Annual Loss (FEMA National Risk Index) Jurisdiction Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual
Loss
Expected
Annual
Loss
Score
Rating
Contra Costa
County $79.2 Billion $2.1 Billion N/A $81.3 Billion 56.8 RelativelyModerate Expected annual loss scores are calculated utilizing an equation that combines values for exposure, annualized frequency, and historic loss ratios (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio).

4.6.7.9. FEMA Coastal Flooding Risk Index Scores
The coastal flooding Risk Index score and rating represent a community's relative risk for coastal flooding when compared to the rest of the United States. Table 4-142 illustrates the coastal flooding Risk Index rating and score for Contra Costa County.

Table 4-142. Coastal Flooding Risk Index (FEMA National Risk Index) Jurisdiction Rating Score
Contra Costa County Relatively Moderate 57.5
Risk Index scores are calculated using an equation that combines scores for Expected Annual Loss due to natural hazards, Social Vulnerability and Community Resilience (Expected Annual Loss x Social Vulnerability / Community Resilience = Risk Index).

5.6.b
Packet Pg. 266 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 194 Table 4-143 represents the Sea Level Rise Total Risk Score for Contra Costa County, based on the Risk Assessment Methodology, as defined in this Plan. For further details on how the probability, extent, vulnerability, and impact factors were calculated, please refer to Table 4-137 through Table 4-140.

Additional details on how the Total Risk Score was calculated can be found in the Risk Assessment Methodology in Section 4.3 of this Plan.

Table 4-143. Sea Level Rise Total Risk Score
Hazard
Event
Probability Consequence Total Risk
Probability
Factor Extent Vulnerability Impact ConsequenceScore
Total Risk
Score*
Sea Level Rise 2 12 6 17 35 37
Consequence: Sum of all weighted factors.

Extent: Sum of the weighted Extent factors.

Vulnerability: Sum of the weighted Vulnerability factors.

Impact: Sum of the weighted Impact factors.

The Total Risk Score is a measure of Probability and Consequence.

5.6.b
Packet Pg. 267 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 195

4.6.8. Severe Weather

4.6.8.1. Description
For the purposes of this Plan, severe weather includes those hazards that are typically produced during severe thunderstorms (i.e., hail, strong winds, and tornado), heavy rainfall, and heat wave.

Severe Thunderstorms
A thunderstorm is a rain shower during which you hear thunder and since thunder includes lightning, then all thunderstorms include lightning. However, a thunderstorm is classified as severe when it contains one (1) or more of the following – hail one (1) inch or greater, winds gusting in excess of 58 mph, and/or a tornado. 230
Included below are the hazards that comprise a severe thunderstorm – hail, strong winds, tornado. Each hazard is examined independently, but it is recognized that these could occur simultaneously.

Hail
Hail is a form of precipitation that consists of solid ice that forms inside thunderstorm updrafts. During a thunderstorm, hail forms when raindrops are carried upward by the thunderstorm’s updrafts into extremely cold air and freeze. As the hailstones continue to be carried upward, they continue to collide with liquid water drops that freeze into the surface of the hailstone. Once the thunderstorm’s updraft can no longer hold the weight of the hailstone, which occurs when the updraft weakens or the hailstone is too heavy, then the hail falls. When a hailstone encounters different liquid water content conditions and temperatures within the thunderstorms, it causes hailstone to have layers of clear and cloudy ice. The speed at which hail falls primarily depends on four (4) characteristics – hail size, friction between the hailstone and surrounding air, local wind conditions (horizontal and vertical), and degree of melting of the hailstone. There is much uncertainty in the average speed hail falls; however, NOAA developed the estimates shown on Table 4-144.
231
Table 4-144. Hail Speed Estimates
Hail Size (inches) Fall Speed (mph)
Less than 1 9 – 25
1 – 1.75 20 – 40
2 – 4 44 – 72
4 or greater Over 100
230 NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Thunderstorm Basics. Retrieved from https://www.nssl.noaa.gov/education/svrwx101/thunderstorms/. 231 NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Hail Basics. Retrieved from https://www.nssl.noaa.gov/education/svrwx101/hail/.

5.6.b
Packet Pg. 268 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 196 Strong Winds
Strong winds, also known as damaging winds, are classified as exceeding 58 mph and often originate from thunderstorms. 232 Most severe thunderstorm winds that cause damage at the ground are a result of outflow generated by the downdraft of a thunderstorm. Table 4-145 outlines the different types of strong winds. 233
In coastal regions a strong wind is called a gale. Gale winds are sustained surface winds between 34 and 47 knots (39 to 54 mph).

Table 4-145. Types of Strong Winds
Type Description
Straight-line Wind Term used to define any thunderstorm wind that is not associated with a rotation and is used mainly to differentiate from tornadic winds.

Downdraft A small-scale column of air that rapidly winds towards the ground.

Macroburst
An outward burst of strong winds at or near the surface with horizontal dimensions larger than 2.5 miles and occurs when a strong downdraft reaches the surface.

Macroburst winds may begin over a smaller area and then spread out over a wider area, sometimes producing damage similar to a tornado. Although usually associated with thunderstorms, macrobursts can occur with showers too weak to produce thunder.

Microburst
A small, concentrated downburst that produces an outward burst of strong winds at or near the surface. Microbursts are small (less than 2.5 miles across) and short-lived (five (5) to 10 minutes) with maximum windspeeds sometimes exceeding 100 mph.

There are two (2) kinds of microbursts – wet and dry. A wet microburst is accompanied by heavy precipitation at the surface. Dry microbursts, common in places like the high plains and the intermountain west, occur with little or no precipitation reaching the ground.

Gust Front
The leading edge of rain-cooled air that clashes with warmer thunderstorm inflow. Gust fronts are characterized by a wind shift, temperature drop, and gusty winds out ahead of a thunderstorm. Sometimes the winds push up air above them, forming a shelf cloud or detached roll cloud.

Derecho
A widespread, long-lived windstorm that is associated with a band of rapidly moving showers or thunderstorms. A typical derecho consists of numerous downbursts and downburst clusters. By definition, if the wind damage swath extends more than 240 miles and includes wind gusts of at least 58 mph or greater along most of its length, then the event may be classified as a derecho.

Haboob A wall of dust that is pushed out along the ground from a thunderstorm downdraft at high speeds.
*A downburst is the general term used to broadly describe macro and microbursts.

Tornado
A tornado is a narrow, violently rotating column of air that extends from a thunderstorm to the ground. A tornado is hard to see unless it forms a condensation funnel made up of water droplets, dust, and debris.

Tornadoes are among the most violent phenomena of all atmospheric storms and atmospheric scientists continue to conduct research to better understand how tornadoes form. Tornadoes come from mainly 232 Federal Emergency Management Agency. (n.d.). Strong Wind. Retrieved from https://hazards.fema.gov/nri/strong-wind.
233 NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Types of Damaging Winds. Retrieved from https://www.nssl.noaa.gov/education/svrwx101/wind/types/.

5.6.b
Packet Pg. 269 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 197 two (2) types of thunderstorms – supercell and non-supercell. 234 Table 4-146 outlines the types of tornadoes. 235
Table 4-146. Types of Tornadoes
Type Description
Supercell
The most common and destructive tornadoes occur from supercells. A supercell is a rotating thunderstorm with a well-defined radar circulation called a mesocyclone.

Supercells can also produce damaging hail, severe non-tornadic winds, frequent lightning, and flash floods. The rotating updraft from a supercell is the key development for a tornado. One way a column of air can begin to rotate is from wind shear when winds at two (2) different levels above the ground blow at different speeds or in different directions. Once the updraft is rotating and fed with warm moist air flowing in the ground level, a tornado can form.

Non-Supercell
Nearly 20% of all tornadoes are associated with lines of strong thunderstorms called quasi-linear convective systems (QLCS). QLCS tornadoes frequently occur during the late night and early morning hours. These tornadoes, however, tend to be weaker and shorter-lived on average than those associated with supercell thunderstorms. NOAA’s National Severe Storms Laboratory (NSSL) researchers are looking for ways to detect QLCS tornadoes more effectively.

Another type of non-supercell tornado is a landspout. A landspout is a tornado with a narrow, rope-like condensation funnel that forms while the thunderstorm cloud is still growing and there is no rotating updraft - the spinning motion originates near the ground.

Heavy Rainfall
There is no single definition for heavy (or extreme) rainfall. However, meteorologists consider instances where the amount of precipitation (rain or snow) experienced in a location substantially exceeds normal amounts. The amount of precipitation needed to qualify as heavy rain varies with location and season.

Rainfall events share characteristics such as high moisture and an atmospheric disturbance (e.g., winter storm, atmospheric river) and when these conditions persist over an area the more rainfall an area will receive. 236 Heavy rainfall is most frequently measured by tracking the frequency of events, analyzing the mean return period, and measuring the amount of precipitation in a certain period (most typically inches of rain within a 24-hour period) 237.

Atmospheric River
A relatively common weather pattern that brings heavy rainfall and mountain snow to California is often referred to as an atmospheric river. About 30% to 50% of the annual precipitation in the west coast states occurs during a few atmospheric river events and approximately 80% of the levee breaches in the California’s Central Valley are associated with atmospheric rivers. 238 Atmospheric rivers are long,
concentrated regions in the atmosphere that transport moist air from the tropics to higher latitudes. The combination of moist air and high wind speeds produce heavy precipitation upon landfall, especially over mountainous terrain. As atmospheric rivers move over land, conditions can be similar to a tropical cyclone 234 NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Tornado Basics. Retrieved from https://www.nssl.noaa.gov/education/svrwx101/tornadoes/. 235 NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Types of Tornadoes. Retrieved from https://www.nssl.noaa.gov/education/svrwx101/tornadoes/types/. 236 National Oceanic and Atmospheric Administration. (2018). Ask the Scientist: Extreme Rainfall, Why it Happens and How We Predict It. Retrieved from https://www.noaa.gov/stories/ask-scientist-extreme-rainfall-why-ithappens-and-how-we-predict-it. 237 United States Environmental Protection Agency. (2023). Climate Change Indicators: Heavy Precipitation.

Retrieved from https://www.epa.gov/climate-indicators/climate-change-indicators-heavy-precipitation. 238 Monroe, R. (2019). New Scale To Characterize Strength And Impacts Of Atmospheric River Storms. Retrieved from https://scripps.ucsd.edu/news/new-scale-characterize-strength-and-impacts-atmospheric-river-storms.

5.6.b
Packet Pg. 270 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 198 leading to flash flooding, mudslides, cyclone force winds, increased wave heights, and catastrophic damage to life and property.
239
Heat Wave / Extreme Heat
The definition of a heat wave varies based on different factors, such as location, weather conditions (e.g., temperature, humidity, cloud cover) and the time of year. 240 However, excessive/extreme heat can be defined as a prolonged period of excessively hot weather, with temperatures above the average high. 241 Heat alone does not make high temperatures a threat; both humidity and heat combined is what makes high temperatures a dangerous. 242 The Heat Index is a measure of how hot it really feels when relative humidity is factored in with the actual air temperature (i.e., ambient temperature).

Figure 4-19 illustrates NWS’ Heat Index Chart. The NWS primarily uses Heat Index values to determine excessive heat events and issue the appropriate advisories. 243 Figure 4-19. National Weather Service Heat Index Chart
239 National Oceanic and Atmospheric Administration. (2023). Atmospheric Rivers: What are They and How Does NOAA Study Them? Retrieved from https://research.noaa.gov/2023/01/11/atmospheric-rivers-what-are-they-andhow-does-noaa-study-them/. 240 U.S. Environmental Protection Agency and the Centers for Disease Control and Prevention. (2016). Climate Change and Extreme Heat: What You Can Do to Prepared. Retrieved from https://www.epa.gov/sites/default/files/2016-10/documents/extreme-heat-guidebook.pdf. 241 Federal Emergency Management Agency. (n.d.). Extreme Heat | What. Retrieved from https://community.fema.gov/ProtectiveActions/s/article/Extreme-Heat-What. 242 National Oceanic and Atmospheric Administration. (2022). Heat Index. Retrieve from https://www.noaa.gov/jetstream/global/heat-index#.
243 National Weather Service. (n.d.). Heat Forecast Tools. Retrieved from https://www.weather.gov/safety/heatindex.

5.6.b
Packet Pg. 271 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 199

4.6.8.2. Hazard Location
Severe Thunderstorms (i.e., hail, strong winds, and tornado), heavy rainfall, atmospheric river, and heat wave can occur anywhere in Contra Costa County. Figure 4-20 illustrates hail events within five (5) miles of Contra Costa County that occurred between 1950 and 2023.

Figure 4-20. Contra Costa County Hail History (1950 – 2023)

5.6.b
Packet Pg. 272 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 200 Figure 4-21 illustrates strong wind events within five (5) miles of Contra Costa County that occurred between 1950 and 2023.

Figure 4-21. Contra Costa County Strong Wind History (1950 – 2023)

5.6.b
Packet Pg. 273 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 201 Figure 4-22 illustrates tornado events within five (5) miles of Contra Costa County that occurred between 1950 and 2023.

Figure 4-22. Contra Costa County Tornado History (1950 – 2023)

5.6.b
Packet Pg. 274 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 202

4.6.8.3. Hazard Extent/Intensity
Severe weather can be life threatening and can cause substantial damage to infrastructure and property.

The extent of damage caused by severe weather depends on the type of severe weather, strength, and location.

Figure 4-23 illustrates the severe thunderstorm outlook categories used by the NWS Storm Prediction Center (SPC) when issuing Severe Thunderstorm Outlooks.

Figure 4-23. SPC Severe Thunderstorm Outlook Categories Hail can vary in shapes and sizes, and only the very large hailstones pose a serious risk to life safety.

NWS reports hail size by comparing the hailstone with traditional object to size conversion for assessment and translation of severe hail reports. Table 4-147 lists the traditional conversion of hail size descriptions. 244
Table 4-147. Converting Traditional Hail Size Descriptions Hail Size
(inches) Object Analog Reported

0.25 Pea

0.50 Mothball

0.75 Penny

0.88 Nickel

1.00 Quarter

1.50 Walnut, ping pong
244 NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Hail Basics. Retrieved from https://www.nssl.noaa.gov/education/svrwx101/hail/.

5.6.b
Packet Pg. 275 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 203 Hail Size
(inches) Object Analog Reported

1.75 Golf ball

2.50 Tennis ball

2.75 Baseball

3.00 Teacup

4.00 Softball

4.50 Grapefruit
The Beaufort Wind Scale was developed to estimate and report wind speeds when a measuring apparatus is not available (e.g, open sea). It was invented in the 1805 by Sir Francis Beaufort of the British Navy as a way to interpret wind conditions at sea. Since then, the scale has been modified to include the effects on land. Table 4-148 outlines the 13 force classification that comprise the Beaufort Wind Scale. 245
Table 4-148. Beaufort Wind Scale
Force Wind
(knots) Classification
Appearance of Wind Effects
On the Water On Land
0 < 1 Calm Sea surface smooth and mirrorlike. Calm, smoke rises vertically. 1 1 – 3 Light Air Scaly ripples and no foam crests. Smoke drift indicates wind direction and still wind vanes.
2 4 – 6 Light Breeze Small wavelets, crests glassy, and no breaking.

Wind felt on face, leaves rustle,
and vanes begin to move.
3 7 – 10 Gentle Breeze Large wavelets, crests begin to
break, and scattered whitecaps.

Leaves and small twigs constantly
moving, and light flags extended.
4 11 – 16 Moderate
Breeze
Small waves of one (1) to four (4)
feet becoming longer with
numerous whitecaps.

Dust, leaves, and loose paper
lifted, and small tree branches
move.
5 17 – 21 Fresh Breeze
Moderate waves of four (4) to
eight (8) feet taking longer form,
many whitecaps, and some spray.

Small trees and leaves begin to
sway.
6 22 – 27 Strong Breeze
Larger waves of eight (8) to 13
feet, whitecaps are common, and
more spray.

Larger tree branches moving and
whistling in wires.
7 28 – 33 Near Gale
Sea heaps up, waves are 13 to 19
feet, white foam streaks off
breakers.

Whole trees moving and
resistance felt walking against
wind.
8 34 – 40 Gale
Moderately high waves (18 to 25
feet) of greater length, edges of
crests begin to break into spindrift,
and foam blown in streaks.

Twigs breaking off trees and
generally impedes progress.
9 41 – 47 Strong Gale
High waves (23 to 32 feet), sea
begins to roll, dense streaks of
foam, and spray may reduce
visibility.

Slight structural damage occurs,
and slate blows off roofs.
245 National Weather Service. (n.d.). Beaufort Wind Scale. Retrieved from https://www.spc.noaa.gov/faq/tornado/beaufort.html.

5.6.b
Packet Pg. 276 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 204 Force Wind
(knots) Classification
Appearance of Wind Effects
On the Water On Land
10 48 – 55 Storm
Very high waves (29 to 41 feet)
with overhanging crests, sea white
with densely blown foam, heavy
rolling, and lowered visibility.

Seldom experienced on land, trees
broken or uprooted, and
considerable structural damage.
11 56 – 63 Violent Storm
Exceptionally high waves (37 to 52
feet), foam patches cover sea, and
visibility more reduced.
--
12 > 63 Hurricane
Air filled with foam, waves over 45
feet, sea completely white with
driving spray, and visibility greatly
reduced.

See Saffir-Simpson Hurricane
Wind Scale.

Tornado rating, based on the Enhance Fujita Scale (EF Scale), is assigned after tornado-related damage is surveyed. The EF Scale is based on the estimated wind speeds and related damage. Table 4-149 outlines the EF Scale. When tornado damages are surveyed, they are compared to a list of Damage Indicators and Degrees of Damage which help to better estimate the range of wind speeds the tornado likely produced. The EF Scale was revised from the original Fujita Scale and became operational in February 2007. 246
Table 4-149. Enhanced Fujita Scale
EF Rating 3 Second Gust
(mph)
0 65 – 85
1 86 – 110
2 111 – 135
3 136 – 165
4 166 – 200
5 Over 200
The NWS HeatRisk Tool Prototype is a color numeric-based index that provides a forecast of the potential level of risk for heat-related impacts to occur in a 24-hour period. This serves as a supplementary tool for official NWS heat products and is meant to provide risk guidance for decision-makers and heat-vulnerable populations who require certain actions at levels that may be below the NWS heat product thresholds.

Table 4-150 outlines the NWS HeatRisk categories and risk of heat-related impacts. 247 Table 4-150. NWS HeatRisk Categories
Category Risk of Heat-Related Impacts
0 Green Little to no risk from expected heat.
1 Yellow Minor: This level of heat affects primarily those individuals extremely sensitive to heat, especially when outdoors without effective cooling and/or adequate hydration. 246 National Weather Service. (n.d.). The Enhance Fujita Scale (EF Scale). Retrieved from https://www.weather.gov/oun/efscale.
247 National Weather Service. (n.d.). NWS HeatRisk Prototype. Retrieved from https://www.wrh.noaa.gov/wrh/heatrisk/.

5.6.b
Packet Pg. 277 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 205 Category Risk of Heat-Related Impacts
2 Orange
Moderate: This level of heat affects most individuals sensitive to heat, especially those without effective cooling and/or adequate hydration. Impacts possible in some health systems and in heat-sensitive industries.
3 Red
Major: This level of heat affects anyone without effective cooling and/or adequate hydration. Impacts likely in some health systems, heat-sensitive industries, and infrastructure.
4 Magenta
Extreme: This level of rare and/or long-duration extreme heat with little to no overnight relief affects anyone without effective cooling and/or adequate hydration. Impacts likely in most health systems, heat-sensitive industries, and infrastructure.

The HeatRisk takes into consideration the following – how unusual the heat is for the time of the year, the duration of the heat including both daytime and nighttime temperatures, and those temperatures that pose an elevated risk of heat-related impacts based on data from the CDC.

The Atmospheric River Scale was developed in collaboration with the Center for Western Water and Weather Extremes at Scripps Institution of Oceanography at University of California San Diego and National Weather Service. The scale uses the amount of water vapor within the atmospheric river as its basis and a period of 24 to 48 hours as its standard measurement of duration. For example, if an atmospheric river remains over an area for over 48 hours the category is increased one and if it is less than 24 hours it is decreased by a category. The Atmospheric River Scale has five (5) categories outlined in Table 4-151.
248
Table 4-151. Atmospheric River Scale
Category Description
1 Weak Primarily beneficial.
2 Moderate Mostly beneficial, but also hazardous.
3 Strong Balance of beneficial and hazardous.
4 Extreme Mostly hazardous, but also beneficial.
5 Exceptional Primarily hazardous.

4.6.8.4. Warning Time
The NWS SPC is responsible for issuing severe thunderstorms and tornado advisories, as conditions warrant. Table 4-152 outlines the severe thunderstorms and tornado advisories. 249 Table 4-152. NWS Severe Weather Advisories
Type Description
Severe Thunderstorm
Watch
Issued by the NOAA SPC when conditions are favorable for the development of severe thunderstorms in and close to the watch area. The size of the watch can vary depending on the weather situation. Severe thunderstorm watches are usually issued for a duration of four (4) to eight (8) hours. They are normally issued well in advance of the actual occurrence of severe weather.
248 Monroe, R. (2019). New Scale To Characterize Strength And Impacts Of Atmospheric River Storms. Retrieved from https://scripps.ucsd.edu/news/new-scale-characterize-strength-and-impacts-atmospheric-river-storms. 249 National Weather Service. (n.d.). National Weather Service Glossary. Retrieved from https://w1.weather.gov/glossary/.

5.6.b
Packet Pg. 278 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 206 Type Description
Severe Thunderstorm
Warning
Issued by the local NWS Forecast Office when either a severe thunderstorm is indicated by radar, or a spotter reports a thunderstorm producing hail one (1) inch or larger in diameter and/or winds equal or exceed 58 mph. Severe thunderstorm warnings are usually issued for a duration of one (1) hour. They can be issued without a Severe Thunderstorm Watch being already in effect. Severe thunderstorms can produce tornadoes with little or no advance warning.

Tornado Watch
Issued by the SPC when conditions are favorable for the development of tornadoes in and close to the watch area. The size of the watch can vary depending on the weather situation. Tornado watches are usually issued for a duration of four (4) to eight (8) hours. They are normally issued well in advance of the actual occurrence of tornadoes.

Tornado Warning
Issued by the local NWS Forecast Office when either a tornado is indicated by radar, or sighted by spotters. Tornado warnings are usually issued for a duration of around 30 minutes. They can be issued without a Tornado Watch being already in effect Gale Watch
Issued by the local NWS Forecast Office for locations along the water when one (1) or both of the following conditions is possible to begin within 36 hours and is not directly associated with a tropical cyclone – sustained winds of 34 to 47 knots (39 to 55 mph) or frequent gusts (duration of two (2) or more hours) between 34 to 47 knots (39 to 55 mph).

Gale Warning
Issued by the local NWS Forecast Office for locations along the water when one (1) or both of the following conditions is expected to begin within 36 hours and is not directly associated with a tropical cyclone – sustained winds of 34 to 47 knots (39 to 55 mph) or frequent gusts (duration of two (2) or more hours) between 34 to 47 knots (39 to 55 mph). At this point, vessel need to be secure at port.

Heavy rainfall can lead to flooding, which can be unexpected and leave a small window of time for evacuation if it is required. The NWS San Francisco Bay Area Forecast Office is responsible for issuing flood advisories and Flash Flood Warnings Impact-Based Warnings for events that occur within approximately six (6) hours of heavy rainfall in Contra Costa County. Refer to the Flood section of this Plan for more information on the warning time during a heavy rainfall event.

During an excessive heat event, the NWS San Francisco Bay Area Forecast Office issues excessive heat advisories, watches, and warnings. Table 4-153 outlines the heat-related products issued by the local NWS Forecast Office. NWS’ local offices collaborate with local agencies (e.g., emergency managers, public health professionals) to determine when an alert should be issued for the local area by establishing heat index thresholds for each advisory.

Table 4-153. NWS Excessive Heat Advisories
Type Definition
Excessive Heat Outlook
Issued when the potential exists for an excessive heat event in the next 3-7 days. An Outlook provides information to those who need considerable lead time to prepare for the event.

Heat Advisory
Issued within 12 hours of the onset of extremely dangerous heat conditions.

Generally, an advisory is issued when the heat index values are expected to reach 100°F or higher for at least two (2) days, and nighttime air temperatures will not drop below 75°F.

Excessive Heat Watch
Issued when conditions are favorable for an excessive heat event in the next 24 to 72 hours. Generally, a watch is issued when the risk of a heat wave has increased, but its occurrence and timing is still uncertain

5.6.b
Packet Pg. 279 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 207 Type Definition
Excessive Heat Warning
Issued within 12 hours of the onset of extremely dangerous heat conditions.

Generally, a warning is issued when the heat index values are expected to reach 105°F or higher for at least two (2) days and nighttime air temperatures will not drop below 75°F.

4.6.8.5. Probability and Frequency
The probability of occurrence for severe weather in Contra Costa County is high because significant severe weather events are likely to occur annually.

Probability of Future Hazard Events
The hail annualized frequency value represents the average number of recorded hail hazard occurrences, in event days, per year over the period of record (34 years). Table 4-154 outlines the annualized frequency for hail, based on FEMA NRI data, for Contra Costa County.

Table 4-154. Hail Annualized Frequency (FEMA National Risk Index) Location Events on Record
(1986 – 2021) Annualized Frequency
Contra Costa County 2 0.0 events per year
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year.

The strong wind annualized frequency value represents the average number of recorded strong wind hazard occurrences, in event days, per year over the period of record (34 years). Table 4-155 outlines the annualized frequency for strong winds, based on FEMA NRI data, for Contra Costa County.

Table 4-155. Strong Wind Annualized Frequency (FEMA National Risk Index) Location Events on Record
(1986 – 2021) Annualized Frequency
Contra Costa County 2 0.0 events per year
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year.

The tornado annualized frequency value represents the average number of recorded tornado hazard occurrences, in event days, per year over the period of record (72 years). Table 4-156 outlines the annualized frequency for tornadoes, based on FEMA NRI data, for Contra Costa County.

Table 4-156. Tornado Annualized Frequency (FEMA National Risk Index) Location Events on Record
(1950 – 2021) Annualized Frequency
Contra Costa County 5 0.1 events per year
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year.

The heat wave annualized frequency value represents the average number of recorded heat wave hazard occurrences in event days, per year over the period of record (16 years). Table 4-157 outlines the annualized frequency for heat waves, based on FEMA NRI data, for Contra Costa County.

5.6.b
Packet Pg. 280 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 208 Table 4-157. Heat Wave Annualized Frequency (FEMA National Risk Index) Location Events on Record
(2005 – 2021)
Annualized Frequency
Contra Costa County 27 1.8 events per year
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year.

4.6.8.6. Past Events
NCEI has reported 95 severe thunderstorm events which include 92 high wind events (58 mph or greater) and five (5) tornado events between 1950 – 2023. There have been no hail events greater than one (1) inch reported by NCEI. Additionally, NCEI has reported 35 heavy rainfall events between 1950 and 2023 in Contra Costa County. Additionally, there have been eight (8) flood disasters, and six (6) severe storm disasters declared in Contra Costa County between 1950 and 2023. A notable event occurred between December 26, 2022, through January 17, 2023, a series of six (6) storm systems moved through the San Francisco Bay area resulting in widespread flooding, including river flooding. In Contra Costa County, the event resulted in a series of Flood Warnings and rainfall amounts ranged from 6.2 inches to 20.07 inches. 250 On January 9, 2023, a Major Disaster Declaration (DR-3591) was issued for this event.

Table 4-158 lists strong wind events, Table 4-159 lists tornado events, Table 4-160 lists heavy rainfall events, and Table 4-161 lists heat events that have occurred in the Contra Costa County between 1950 and 2023 according to NCEI.

Table 4-158. Strong Winds Events (1950 – 2023)
Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 3/28/2023 07:48 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS
(ZONE) East Bay Hills CA 3/28/2023 09:40 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 3/28/2023 10:10 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 3/21/2023 13:04 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 3/21/2023 14:29 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 3/14/2023 07:45 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS
(ZONE) East Bay Hills CA 3/14/2023 11:20 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS
(ZONE) East Bay Hills CA 3/9/2023 21:20 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 2/21/2023 13:33 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 2/21/2023 15:22 High Wind 0 0 0.00K 0.00K 250 National Weather Service, San Francisco Bay Area, California Weather Forecast Office. (2023). A Parade of Storms Impact Bay Area. Retrieved from https://www.weather.gov/mtr/AtmosphericRivers_12_2022-01_2023.

5.6.b
Packet Pg. 281 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 209 Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage

EAST BAY HILLS
(ZONE) East Bay Hills CA 2/21/2023 16:30 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS
(ZONE) East Bay Hills CA 12/27/2022 01:50 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS
(ZONE) East Bay Hills CA 12/27/2022 03:10 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 12/7/2020 03:15 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 10/25/2020 23:50 High Wind 0 0 0.00K 0.00K
WALNUT HGTS Contra Costa
County CA 8/16/2020 02:50 Thunderstorm
Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 11/26/2019 19:18 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 11/26/2019 19:28 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 2/14/2019 01:28 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 2/14/2019 03:49 High Wind 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 1/16/2019 1528 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 1/16/2019 16:21 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 1/16/2019 17:13 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 1/16/2019 17:28 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 1/16/2019 18:28 High Wind 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 1/16/2019 18:38 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 1/9/2019 00:10 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 11/28/2018 23:45 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 10/7/2018 02:00 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 10/8/2017 21:15 High Wind 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 2/20/2017 16:50 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 2/17/2017 09:07 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 2/17/2017 11:04 High Wind 0 0 0.00K 0.00K

5.6.b
Packet Pg. 282 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 210 Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 2/9/2017 12:09 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 2/7/2017 04:50 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 2/7/2017 05:28 High Wind 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 2/7/2017 09:30 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 1/22/2017 01:18 High Wind 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 1/7/2017 07:00 High Wind 1 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 2/6/2015 11:10 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 2/6/2015 11:18 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 2/6/2015 13:00 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 2/6/2015 14:28 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 12/30/2014 16:00 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 12/11/2014 04:00 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 12/11/2014 07:18 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 12/11/2014 07:30 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 10/27/2013 19:45 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 10/27/2013 20:12 High Wind 0 0 25.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 10/27/2013 23:18 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 10/4/2013 01:45 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 5/1/2013 02:00 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 5/1/2013 07:17 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 4/8/2013 00:18 High Wind 0 0 0.00K 0.00K

5.6.b
Packet Pg. 283 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 211 Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 4/8/2013 02:12 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 11/28/2012 11:28 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 12/1/2011 01:45 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 3/19/2011 20:00 High Wind 0 0 100.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 2/15/2011 20:30 High Wind 0 0 150.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 1/20/2010 07:00 High Wind 0 1 245.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 1/19/2010 03:00 High Wind 0 0 40.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 1/19/2010 03:00 High Wind 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 1/19/2010 04:00 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 11/28/2009 07:00 High Wind 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 10/27/2009 11:00 High Wind 0 0 50.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 10/27/2009 21:00 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 10/13/2009 08:00 High Wind 0 0 2.500M 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 10/13/2009 08:00 High Wind 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 10/13/2009 08:00 High Wind 0 0 20.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 4/14/2009 16:00 High Wind 0 0 80.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 2/15/2009 03:39 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 1/4/2008 90:00 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 1/4/2008 09:00 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 1/4/2008 09:00 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 1/4/2008 10:00 High Wind 0 0 0.00K 0.00K

5.6.b
Packet Pg. 284 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 212 Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 1/4/2008 12:00 High Wind 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 1/4/2008 12:00 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 12/27/2006 08:00 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 2/27/2006 10:00 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 2/27/2006 18:54 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 2/27/2006 19:00 High Wind 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 12/31/2005 03:00 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 12/31/2005 07:46 High Wind 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 12/18/2005 05:00 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 12/18/2005 07:57 High Wind 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 12/18/2005 13:00 High Wind 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 12/1/2005 12:00 High Wind 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 12/1/2005 12:28 High Wind 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 12/1/2005 13:30 High Wind 0 0 0 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 12/1/2005 17:39 High Wind 0 0 0 0.00K
TOTAL 1 1 3.260M 0.00K
Table 4-159. Tornado Events (1950 – 2023)
Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage
BRENTWOOD Contra Costa
County CA 1/23/2010 12:54 Tornado (EF1) 0 0 25.00K 0.00K RICHMOND Contra Costa
County CA 12/5/1998 19:30 Tornado (F0) 0 0 200.00K 0.00K BRENTWOOD Contra Costa
County CA 2/19/1998 12:30 Tornado (F0) 0 0 50.00K 0.00K

CONTRA COSTA
CO.

Contra Costa
County CA 9/18/1989 17:00 Tornado (F0) 0 0 0.00K 0.00K

CONTRA COSTA
CO.

Contra Costa
County CA 9/18/1989 17:10 Tornado (F0) 0 0 0.00K 0.00K
TOTAL 0 0 275.00K 0.00K

5.6.b
Packet Pg. 285 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 213 Table 4-160. Heavy Rainfall Past Events
Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage
AMBROSE Contra Costa
County CA 1/10/2017 18:57 Heavy Rain 0 0 0.00K 0.00K
DIABLO Contra Costa
County CA 2/9/2015 04:11 Heavy Rain 0 0 0.00K 0.00K
ORINDA VLG Contra Costa
County CA 3/13/2012 00:00 Heavy Rain 0 0 50.00K 0.00K
GIANT Contra Costa
County CA 6/4/2011 03:00 Heavy Rain 0 0 0.00K 50.00K
WALNUT CREEK Contra Costa
County CA 4/11/2010 17:00 Heavy Rain 0 0 10.00K 0.00K

SW SJ VALLEY
(ZONE)
SW San
Joaquin Valley
(Zone)
CA 9/3/2001 07:42 Heavy Rain 0 0 0.00K 0.00K

E CENTRAL SJ
VALLEY
E Central San
Joaquin Valley
(Zone)
CA 9/3/2001 07:42 Heavy Rain 0 0 0.00K 0.00K

KERN CTY MTNS
(ZONE)
Kern County
Mountains
(Zone)
CA 9/3/2001 12:35 Heavy Rain 0 0 0.00K 0.00K

INDIAN WELLS

VLY (ZONE)
Indian Wells
Valley (Zone) CA 9/3/2001 12:35 Heavy Rain 0 0 0.00K 0.00K

SE KERN CTY

DESERT (ZONE)
SE Kern
County Desert
(Zone)
CA 9/3/2001 12:35 Heavy Rain 0 0 0.00K 0.00K
MONO (ZONE) Mono (Zone) CA 7/5/2001 14:30 Heavy Rain 0 0 0.00K 0.00K MONO (ZONE) Mono (Zone) CA 7/2/2001 19:30 Heavy Rain 0 0 0.00K 0.00K

E CENTRAL SJ
VALLEY
E Central San
Joaquin Valley
(Zone)
CA 9/1/2000 03:40 Heavy Rain 0 0 0.00K 250.00K

E CENTRAL SJ

VALLEY (ZONE)
E Central San
Joaquin Valley
(Zone)
CA 2/13/2000 00:00 Heavy Rain 0 0 0.00K 0.00K

E CENTRAL SJ

VALLEY (ZONE)
E Central San
Joaquin Valley
(Zone)
CA 2/1/2000 01:00 Heavy Rain 0 0 0.00K 0.00K

SOUTHERN SAN

JOAQUIN VALLEY
(ZONE)
Southern San
Joaquin Valley CA 9/22/1999 07:30 Heavy Rain 0 0 0.00K 5.00M

CENTRAL SJV
(ZONE)
Central San
Joaquin Valley
(Zone)
CA 9/9/1998 01:00 Heavy Rain 0 0 0.00K 0.00K

SOUTH SJV
(ZONE)
South San
Joaquin Valley
(Zone)
CA 9/4/1998 00:00 Heavy Rain 0 0 0.00K 5.00M

N VENTURA
(ZONE)
N Ventura
(Zone) CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

X N LOS

ANGELES (ZONE)
X N Los
Angeles
(Zone)
CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

W SANTA

BARBARA (ZONE)
W Santa
Barbara
(Zone)
CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

N LOS ANGELES

T X N (ZONE)
N Los Angeles
T X N (Zone) CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

C VENTURA
(ZONE)
C Ventura
(Zone) CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

C LOS ANGELES
(ZONE)
C Los Angeles
(Zone) CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

X SW LOS

ANGELES (ZONE)
X SW Los
Angeles
(Zone)
CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

5.6.b
Packet Pg. 286 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 214 Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage

X W SAN LUIS

OBISPO (ZONE)
X W San Luis
Obispo (Zone) CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

X SE LOS

ANGELES (ZONE)
X SE Los
Angeles
(Zone)
CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

X S VENTURA
(ZONE)
X S Ventura
(Zone) CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

X S SANTA

BARBARA (ZONE)
X S Santa
Barbara
(Zone)
CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

X N SANTA

BARBARA (ZONE)
X N Santa
Barbara
(Zone)
CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

SC SAN LUIS

OBISPO (ZONE)
Sc San Luis
Obispo (Zone) CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

SAN LUIS

OBISPO T SC & X

W (ZONE)
San Luis
Obispo T Sc &
X W (Zone)
CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

S VENTURA T X S
(ZONE)
S Ventura T X
S (Zone) CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

P C SANTA

BARBARA (ZONE)
P C Santa
Barbara
(Zone)
CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K

P C SANTA

BARBARA (ZONE)
P C Santa
Barbara
(Zone)
CA 11/10/1997 02:00 Heavy Rain 0 0 0.00K 0.00K
TOTAL 0 0 60.00K 10.30M
Table 4-161. Heat Events (1950 – 2023)
Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage

EAST BAY

INTERIOR

VALLEYS
East Bay
Interior Valleys CA 7/21/2006 12:00 Heat 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 7/21/2006 12:00 Heat 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 7/22/2006 14:00 Heat 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 7/25/2007 07:00 Heat 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 5/17/2009 10:00 Heat 0 0 10.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 5/17/2009 10:00 Heat 0 10 20.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 5/17/2009 12:00 Heat 0 1 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 6/27/2009 11:00 Heat 1 1 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 6/18/2017 14:00 Heat 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 6/20/2017 20:30 Heat 0 0 0.00K 0.00K

5.6.b
Packet Pg. 287 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 215 Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 4/24/2019 15:00 Heat 0 1 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 8/14/2019 07:00 Heat 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 8/14/2019 16:30 Heat 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys
(Zone)
CA 6/17/2021 15:00 Heat 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 6/10/2022 15:00 Heat 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 6/21/2022 15:00 Heat 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 6/21/2022 15:00 Heat 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 6/21/2022 15:00 Heat 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 8/16/2022 15:00 Heat 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 9/4/2022 09:00 Heat 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 9/4/2022 09:00 Heat 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 9/5/2022 14:00 Heat 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 9/5/2022 14:00 Heat 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 9/6/2022 14:00 Heat 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 9/6/2022 14:00 Heat 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 9/8/2022 14:00 Heat 0 0 0.00K 0.00K TOTAL 1 13 30.00K 0.00K

4.6.8.7. Vulnerability and Impacts
Life Safety and Health: All residents within Contra Costa County would be vulnerable and impacted by severe weather events. A study by the California Energy Commission states that heat wave/extreme heat events have claimed more lives in California than all other disaster events combined.251 However, the underserved and at risk population face unique vulnerabilities and impacts as a result of severe weather.

These groups include, but are not limited to, households in poverty, outdoor workers, individuals with 251 Association of Bay Area Governments. (n.d.). Extreme Heat. Retrieved from https://abag.ca.gov/ourwork/resilience/data-research/extreme-heat.

5.6.b
Packet Pg. 288 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 216 chronic illnesses, those with limited English proficiency, the elderly population and seniors living alone, and undocumented individuals.252
Households in Poverty: Households in poverty include those with an income at or below $24,300 for a household of four (4). In Contra Costa County, households in poverty may live in structures that are less resilient to severe weather which increases the likelihood that severe thunderstorms, strong winds, and heavy rainfall can damage the structures, and cause mold and mildew. Due to fewer financial resources, this population may not be able to complete preparedness and recovery activities (i.e., fix flood damage). Furthermore, this population can be physically harmed or experience a decrease in quality of life due to severe weather. High concentration of this population is located in central Richmond, North Richmond and San Pablo, tracts of Concord and Martinez, and in Bay Point, Pittsburg, and Antioch. Poverty is associated with greater vulnerability to heat wave/extreme heat events in a number of ways. The longstanding association between low income and poor health outcomes, as well as pre-existing health conditions among people in poverty, play a key role in vulnerability. Impoverished and lowincome individuals who are uninsured may be less likely to seek medical help if they become ill, may live in poorly insulated housing, and may also be less likely to use fans or air conditioning out of concern for high utility bills. During extreme heat days, temperatures in uninsulated homes may reach unhealthy temperatures. Households in poverty are located throughout the County, however those in central and eastern Contra Costa may face the greatest exposure from extreme heat.

Individuals Experiencing Homelessness are those who do not have a permanent home, including those who live in their vehicles or temporary shelters. This population is highly exposed to severe weather because they experience a lack of permanent shelter which is often temporary.

Additionally, this population faces greater exposure to extreme heat because they lack access to permanent shelter. Dehydration is common among homeless individuals, which makes health related complications from extreme heat more likely. Homeless individuals are more likely to suffer respiratory infections, which are exacerbated by extreme heat, and those on medication are also at greater risk as some medications interfere with the body's ability to maintain a safe internal temperature during times of extreme temperatures. The homeless population in the central and eastern portion of the County are more vulnerable to heat wave/extreme heat events.

In 2024, there are 2,843 people experiencing homelessness in Contra Costa County, an 18.5% increase from 2023.
253
Outdoor Workers: Includes, but are not limited to, workers in agriculture, construction, building maintenance, landscaping, and refinery operations fields. This population is significantly vulnerable to heat wave/extreme heat events because these jobs, often physically intense, require them to be outside and risk heat related illnesses (e.g., heat cramps, heat exhaustion, heat stroke). Furthermore, outdoor work may also be halted during high temperatures, which can cause significant economic hardships.

Individuals with Chronic Illnesses: Includes those that have long term or permanent health conditions that can be exacerbated by heat wave/extreme heat conditions (e.g., cardiovascular disease, respiratory conditions, diabetes, cerebrovascular diseases). These individuals may be taking medication that can reduce their body’s ability to maintain safe internal temperatures. 252 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.
253 Contra Costa Health. (2024). Health, Housing, and Homelessness Data Reports (Point-in-Time Count).

Retrieved from https://www.cchealth.org/services-and-programs/homeless-services/data.

5.6.b
Packet Pg. 289 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 217 Furthermore, severe weather may cause power outages which can affect those that are electrically dependent.

People with Limited English Proficiency: This group includes those that speak English “less than very well”, per the United States Census Bureau definition. In Conta Costa County, 158,965 people (38.2%) have limited English proficiency (i.e., speak English “less than very well”). This population are more likely to live in low income areas which are also most likely to be located within low lying areas. Flooding due to heavy rainfall can cause significant damage to homes resulting in uninhabitable and unhealthy conditions to live in. Additionally, individuals with limited English proficiency may have limited access to information and resources designed to prevent or mitigate flooding risk due to language or cultural differences. Other languages spoken in the County are primarily Spanish, Mandarin, Cantonese, Tagalog, and Persian. Other than English, the most commonly spoken language in Contra Costa County is Spanish (18.7%). The higher proportion with limited English proficiency occurs in the cities of Richmond, Concord, and San Pablo.

Senior (65 years old and over) and Seniors Living Alone: The elderly population (i.e., seniors), especially those with access and functional needs, may have physical limitations that make it harder to evacuate in the event of an emergency due to severe weather (e.g., flooding due to heavy rainfall). Furthermore, the elderly population may lack access to social connections and community support that can assist in preparing for and responding to emergency events, evacuating, improving home resiliency, managing medical needs, and locating support services.

These individuals are especially vulnerable to the health effects associated with heat wave/extreme heat events. A high concentration of the elderly population lives in central Contra Costa County, Bethel Island, eastern part of Richmond, and several parts of Walnut Creek.

Seniors living alone may have caretakers, but for the most part are living alone. This population is generally more vulnerable compared to other seniors because this group may have mobility issues that prohibits them from taking action during a severe weather event. In 2022, there were approximately 33,102 (8.0%) seniors living alone.254
Undocumented Individuals: Includes people who do not have formal permission to live in the United States (i.e., do not have citizenship, permanent residency, visas, or other similar status).

Additionally, most of this population has outdoor occupations or work in highly unregulated environment which leaves them susceptible to harm from heat wave/extreme heat conditions.

Outdoor work may also be halted during high temperatures, which can cause significant economic hardships. Undocumented agricultural workers may face economic hardship if crops, vineyards, or rangeland are damaged by heat wave/extreme heat conditions. Furthermore, agricultural workers who are undocumented are more likely to be let go when farms experience economic hardship. There are no official counts of how many undocumented individuals live in Contra Costa County, but in 2019 there was an estimate of 63,000.255 254 United States Census Bureau. (2022). DP02: Selected Social Characteristics in the United States (2022: ACS 1-Year Estimates Data Profiles). Retrieved from
https://data.census.gov/table/ACSDP1Y2022.DP02?g=050XX00US06013. 255 Migration Policy Institute. (2019). Profile of the Unauthorized Population: Contra Costa County, CA. Retrieved from https://www.migrationpolicy.org/data/unauthorized-immigrant-population/county/6013.

5.6.b
Packet Pg. 290 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 218 Severe weather will impact County residents differently. For example, extreme heat thresholds for West County are lower than those in Central or East County, even so, West County residents may be particularly vulnerable since they are unaccustomed to continuous high temperatures.

Table 4-162 summarizes the vulnerable and at-risk population for severe weather in Contra Costa County.

Table 4-162. Vulnerability and At Risk Population
Category Estimate Percent
Households in Poverty256 7,600 12.0%
Low Income Households257 25,340 41.0%
Homeless Population258 2,372 0.2%
Population with Disability259 131,448 11.4%
Language Other than English260 416,505 38.0%
Speak English “Less than very
well”261 158,965 14.5%
Spanish Spoken at Home262 204,442 18.7%
Foreign Born263 312,050 27.0%
65 Years and Over264 201,136 17.4%
Seniors (65 years and over) Living
Alone265 45,672 22.7%
Undocumented Individuals266 There are no official counts of how many undocumented individuals live in Contra Costa County, but in 2019 there was an estimate of 63,000. 256 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.
257 Ibid.
258 Contra Costa Health. (2023). Health, Housing, and Homelessness Data Reports (Point-in-Time Count).

Retrieved from https://www.cchealth.org/services-and-programs/homeless-services/data. 259 United States Census Bureau. (2022). S1810: Disability Characteristics (2022: ACS 1-Year Estimates Subject Tables). Retrieved from https://data.census.gov/table/ACSST1Y2022.S1810?g=050XX00US06013. 260 United States Census Bureau. (2022). S1601: Language Spoken at Home (2022: ACS 1-Year Estimates Subject Tables). Retrieved from https://data.census.gov/table/ACSST1Y2022.S1601?g=050XX00US06013. 261 Ibid.
262 Ibid.
263 United States Census Bureau. (2022). DP02: Selected Social Characteristics in the United States (2022: ACS 1-Year Estimates Data Profiles). Retrieved from
https://data.census.gov/table/ACSDP1Y2022.DP02?g=050XX00US06013. 264 United States Census Bureau. (2022). DP05: Demographics and Housing Estimates (2022: ACS 1-Year Estimates Data Profiles). Retrieved from
https://data.census.gov/table/ACSDP1Y2022.DP05?g=050XX00US06013. 265 United States Census Bureau. (2022). DP02: Selected Social Characteristics in the United States (2022: ACS 1-Year Estimates Data Profiles). Retrieved from
https://data.census.gov/table/ACSDP1Y2022.DP02?g=050XX00US06013. 266 Migration Policy Institute. (2019). Profile of the Unauthorized Population: Contra Costa County, CA. Retrieved from https://www.migrationpolicy.org/data/unauthorized-immigrant-population/county/6013.

5.6.b
Packet Pg. 291 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 219 Table 4-166 outlines the vulnerability of the total population exposed to severe weather, and Table 4- 167 outlines the severe weather impacts to population and life safety, underserved/equity population, and essential operations, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Property Damage and Critical Infrastructure: All property and critical infrastructure in Contra Costa County is vulnerable during the severe weather events profiled in this section, but properties that are structurally compromised or in particular vulnerable locations are more susceptible to the impacts of severe weather. Those in higher elevations and on ridges may be more prone to wind damage. Extreme heat events are not known for causing direct damage to buildings, but may damage building systems such as heating, ventilation, and air conditioning (HVAC) systems. Mobile homes and properties in poor condition or closer to overhead power lines and large trees may be more vulnerable to damage. In Contra Costa County, approximately 1.3% of the occupied housing units are mobile homes.267 Due to the unpredictability of thunderstorm strength and path, most critical infrastructure located above ground is equally exposed to the storm’s impacts.

Electrical transmission and distribution lines are power lines that carry high voltage electricity between power plants and customers. There are a number of transmission lines throughout the County primarily owned by Pacific Gas & Electric (PG&E) and other lines in the eastern portion of the County are owned by Western Area Power Administration and the Transmission Agency of Northern California. The entire electric infrastructure is vulnerable to strong winds which can cause power outages and impact residents and businesses. Heat wave/extreme heat conditions will most likely affect electricity transmission and distribution lines within the eastern and central portion of Contra Costa County because temperatures in this area are projected to substantially increase on extreme heat days. Furthermore, extreme heat can cause an increase in air conditioning use during these events which can stress and overload the grid subsequently causing power outages and damage to the lines. 268
Heavy rain and thunderstorms, particularly those that result in hail, could significantly impact motorists travelling along major roadways. Depending on the severity of the storm, these events could slow traffic, reduce visibility, and increase the likelihood of vehicle accidents, which may result in greater traffic delays.

Incapacity and loss of roads are the primary transportation failures resulting from severe weather, mostly associated with secondary hazards. Landslides caused by heavy prolonged rainfall events can block roads. High winds can cause significant damage to trees and power lines, blocking roads with debris, incapacitating transportation, isolating population, and disrupting ingress and egress. Of particular concern are roads providing access to isolated areas and to the elderly. Prolonged obstruction of major routes can disrupt the shipment of goods and other commerce. Large, prolonged storms can have negative economic impacts for an entire region. Severe windstorms and downed trees can create serious impacts on overhead power lines and infrastructure and above ground communication lines. Loss of electricity and phone connection would leave certain portion of the population isolated because residents would be unable to call for assistance.

Extreme heat is not known for causing direct impacts on critical facilities and infrastructure, but some impacts may occur in extreme cases, such as Public Safety Power Shutoff. 267 United States Census Bureau. (2022). S2504: Physical Housing Characteristics for Occupied Housing Units (2022: ACS 1-Year Estimates Subject Tables). Retrieved from https://data.census.gov/table/ACSST1Y2022.S2504?g=050XX00US06013. 268 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.

5.6.b
Packet Pg. 292 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 220 There are a total of 554 critical assets (i.e., schools, nursing homes, fire stations, police stations, and hospitals) throughout the County and 100% of these assets are susceptible to severe weather impacts to varying degrees. Table 4-163 provides a breakdown of critical assets that are located within Contra Costa County. Refer to the flood profile for a breakdown of critical assets within the 100-year and 500- year floodplain (Table 4-101) and the landslide profile for a breakdown of critical assets within medium, high, and very high landslide susceptibility areas (Table 4-122).

Table 4-163. Critical Assets Vulnerable to Severe Weather Asset Estimate Percent
(of total assets)
Schools (public schools, private schools) 360 100.0%
Nursing Homes 78 100.0%
Fire Stations 81 100.0%
Police Stations 24 100.0%
Hospitals 11 100.0%
Table 4-166 outlines the total property value exposed to severe weather and how the changes in development in the past five (5) years, have affected the vulnerability of the community to severe weather.

Table 4-167 outlines the severe weather impacts on total property damage, potential future development, and the economy, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Environment: The environment is highly exposed to all the severe weather events profiled in this Plan.

In Contra Costa County, the following ecosystems and natural resources are vulnerable to severe weather, including extreme heat:
269
Agriculture: Agricultural operations can be significantly damaged by strong winds, hail, and severe thunderstorms. Strong winds can flatten crops and food crops can be damaged by hail.

Additionally, heat wave/extreme heat conditions can damage crops or reduce yield, make crops more difficult to manage, and can lead to the death of crops. For example, wine grapes are expected to experience a decline in fruit quality due to heat wave/extreme heat events. Damage to agriculture due to severe weather can result in economic hardship for the farm owners in the area.

Aquatic: Aquatic habitat (i.e., streams, reservoirs, ponds, and sloughs or channels) are impacted by heat wave/extreme heat. This ecosystem includes the Delta and shoreline areas that are submerged by water. In Contra Costa County, the three (3) large reservoirs include San Pablo Reservoir, Briones Reservoir, and Los Vaqueros Reservoir. Aquatic wildlife species include various duck species, California red-legged frog, western pond turtle, and juvenile and spawning adult Chinook salmon. Extreme heat events can cause water temperatures in aquatic habitats to increase, which can alter water quality and other water characteristics. Native fish species may have a more difficult time surviving in warmer waters and non-native species may out compete native species.

The Delta: The Sacramento-San Joaquin River Delta spans from the City of Pittsburg in the west, Locke in the east, Sacramento to the North, and Tracy to the south. The Delta primarily 269 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.

5.6.b
Packet Pg. 293 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 221 encompasses the northern and easternmost borders of Contra Costa County and provides opportunities for boating, fishing, transportation, and a water source for the County. Severe weather events have the potential to damage harbors, marinas, and outdoor recreation centers within the Delta impacting fishery and recreation based economies. Additionally, extreme heat can alter the Delta’s water quality, and cause water temperatures to rise, fish to die, and algae to grow.

Rangeland: Includes lands where many livestock species (e.g., cattle) are raised and most are located in the eastern portion of Contra Costa County. Temperatures above 100°F can create heat stress, increase the risk of infection, reduce milk production and fertility, and may lead to the death of animals.

Riparian Woodland and Shrub: Riparian woodland and shrub ecosystems consist of Valley foothill riparian, undetermined shrub, and riverine habitat. These areas are scattered throughout Contra Costa County and have numerous wildlife species (e.g., gray fox, striped skunk, broadhanded mole, mule deer, dusky-footed woodrat, yellow warbler, northern flicker, white tailed kite, and Cooper’s hawk). Severe storms can cause trees to fall in riparian ecosystems, which can disrupt the flow of water through the systems and impact aquatic wildlife in the streams.

Wetland: Wetland ecosystems, located adjacent to the San Francisco Bay and Delta, include permanent wetland, seasonal wetland, fresh emergent wetland, alkali wetland, and marshes.

Warmer waters may change wetland habitats to the point that native species can no longer survive. Warmer temperatures may also cause harmful algal growth that can harm both plant and wildlife species.

Table 4-167 outlines severe weather impacts on the environment and economy, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Changes in Development and Impact of Future Development: There have been no significant changes in development that have affected the risks associated with severe weather. Future increases in population within the SHFA may expose more of the population to floods. Growth over the past decade has considerably increased. Between 2010 and 2022, as outlined in Table 3-3, the population in Contra Costa County grew 10.6%, from 1,046,025 to 1,156,966 residents. The Bay Area Association of Governments (ABAG) growth forecasts predict a steady increase in households through 2050. From 2015 to 2050, ABAG projects that the County’s number of households will grow by 44%.270 The ability to withstand impacts lies in rigorous land use practices and consistent enforcement of codes and regulations for new construction. Contra Costa County is StormReady certified by the NWS, which means that the County has achieved the industry standard for severe weather preparedness and communication. Additionally, the County has adopted the International Building Code in response to California mandates. This Code is equipped to deal with the impacts of severe weather events. Land use policies identified in general plans within the planning area also address many of the secondary impacts (e.g., flood and landslide) of the severe weather hazard. With these tools, the planning partners are well equipped to deal with future growth and the associated impacts of severe weather.

Table 4-166 outlines how the changes in development in the past five (5) years have affected the vulnerability of the community to severe weather. Table 4-167 outlines the severe weather impacts on potential future development, as outlined in the risk assessment methodology in Section 4.3 of this Plan. 270 Bay Area Association of Government. (2020). Plan Bay Area 2050 Final Blueprint Growth Pattern. Retrieved from https://planbayarea.org/digital-library/plan-bay-area-2050-final-blueprint-growth-pattern.

5.6.b
Packet Pg. 294 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 222 Effects of Climate Change in Severity of Impacts: Atmospheric rivers are part of the water cycle in the western United States often occurring in the fall and winter, and when beneficial they result in much needed rain to the region. For example, persistent drought events can end when atmospheric rivers make landfall in the area. However, when these systems produce too much water at once it can result in a significant amount of damage. As global temperatures continue to increase, the amount and severity of atmospheric rivers are projected to increase. Warmer air and oceans serve as fuel for these systems to become larger and stronger, and the atmosphere is capable of holding more moisture. Some research shows that atmospheric rivers are expected to be 25% longer and wider resulting in heavy rainfall and strong winds over an area for a longer period of time. As rainfall increases, soil will become extremely saturated and unable to absorb additional water increasing runoff which can overwhelm rivers and result in flooding and landslides. Studies have determined that by 2090 atmospheric river events could cause up to $3.2 Billion of damages annually.
271
As global average temperatures continue to increase, scientists expect that heat wave/extreme heat events will become more common, more severe, and last longer. Subsequently leading to an increase of heat-related illnesses and deaths.272 By the middle of the 21st century (2040 to 2070), Contra Costa County is likely to have an average of 15 to 20 extreme heat days per year. By the end of the century, the County is projected to experience an average of 21 to 37 extreme heat days per year.273 Climate change is expected to increase ambient average air temperature, particularly in the summer.

The outer Bay Area will likely experience greater temperature increases than coastal or bayside jurisdictions, though likely not as great as in eastern portion of the County. The frequency, intensity, and duration of extreme heat events and heat waves are also expected as regional climate impacts.

Table 4-167 outlines the climate change impacts to severe weather in Contra Costa County, as outlined in the risk assessment methodology in Section 4.3 of this Plan. 271 United States Department of Agriculture Climate Hubs. (n.d.). Atmospheric Rivers in the Northwest. Retrieved from https://www.climatehubs.usda.gov/hubs/northwest/topic/atmospheric-rivers-northwest-0. 272 U.S. Environmental Protection Agency and the Centers for Disease Control and Prevention. (2016). Climate Change and Extreme Heat: What You Can Do to Prepared. Retrieved from https://www.epa.gov/sites/default/files/2016-10/documents/extreme-heat-guidebook.pdf. 273 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.

5.6.b
Packet Pg. 295 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Severe Thunderstorm High Significant hazard event is likely to occur annually. 3 N/A Strong Winds / DamagingWinds High Significant hazard event is likely to occur annually. 3 N/ATornado Low Significant hazard event is likely to occur within 100 years. 1 N/AHeavy Rainfall High Significant hazard event is likely to occur annually. 3 N/AHeat Wave / ExtremeHeat High Significant hazard event is likely to occur annually. 3 N/A Severe Thunderstorm
Extent/Intensity Low Historical and/or probabilistic models/studies for this hazard indicate the possibility of a low-intensity incident. 1 3Catastrophic Low Catastrophic hazard event is likely to occur at least once in 51 or more years. 1 3 Strong Winds / DamagingWinds
Extent/Intensity Medium Historical and/or probabilistic models/studies for this hazard indicate the possibility of a medium-intensity incident. 2 6Catastrophic Low Catastrophic hazard event is likely to occur at least once in 51 or more years. 1 3 Tornado
Extent/Intensity Low Historical and/or probabilistic models/studies for this hazard indicate the possibility of a low-intensity incident. 1 3Catastrophic Low Catastrophic hazard event is likely to occur at least once in 51 or more years. 1 3 Heavy Rainfall
Extent/Intensity Medium Historical and/or probabilistic models/studies for this hazard indicate the possibility of a medium-intensity incident. 2 6Catastrophic Low Catastrophic hazard event is likely to occur at least once in 51 or more years. 1 3 Heat Wave / ExtremeHeat
Extent/Intensity Medium Historical and/or probabilistic models/studies for this hazard indicate the possibility of a medium-intensity incident. 2 6Catastrophic Low Catastrophic hazard event is likely to occur at least once in 51 or more years. 1 3

5.6.b
Packet Pg. 296 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Severe Thunderstorm
Population Exposure High 30% or more of the population is exposed to the hazard. 3 9Property Exposure High 25% or more of the total assessed property value is exposed to the hazard. 3 6Changes inDevelopment Low Changes in development have increased thevulnerability/exposure of the community to the hazard by 4%or less. 1 1
Strong Winds / DamagingWinds
Population Exposure Medium 15% to 29% of the population is exposed to the hazard. 2 6Property Exposure Medium 10% to 24% of the total assessed property value is exposed to a hazard. 2 4Changes inDevelopment Low Changes in development have increased thevulnerability/exposure of the community to the hazard by 4%or less. 1 1 Tornado
Population Exposure Low 14% or less of the population is exposed to the hazard. 1 3Property Exposure Low 9% or less of the total assessed property value is exposed to a hazard. 1 2Changes inDevelopment Low Changes in development have increased thevulnerability/exposure of the community to the hazard by 4%or less. 1 1 Heavy Rainfall
Population Exposure High 30% or more of the population is exposed to the hazard. 3 9Property Exposure Medium 10% to 24% of the total assessed property value is exposed to a hazard. 2 4Changes inDevelopment Low Changes in development have increased thevulnerability/exposure of the community to the hazard by 4%or less. 1 1 Heat Wave / ExtremeHeat
Population Exposure High 30% or more of the population is exposed to the hazard. 3 9Property Exposure No Vulnerability None of the total assessed property value is exposed to a hazard. 0 0Changes inDevelopment Low Changes in development have increased thevulnerability/exposure of the community to the hazard by 4%or less. 1 1

5.6.b
Packet Pg. 297 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Severe Thunderstorm
P
o
p
ulatio
n an
d
Life
Safety
Low
Populations exposed to this hazard are likely to experienceminimal adverse impacts, such as ambulatory injuries. 1 3
Un
derserved/E
q
uity Low
Underserved populations exposed to the hazard are likely toexperience minimal adverse/disproportionate impacts, suchas ambulatory injuries. 1 3
Pro
perty
Damage Low
Less than $500,000 in property damages is expected from asingle major hazard event or less than 5% of the propertyvalue within the jurisdiction. 1 2
Eco
n
o
mic Low
Total economic impact is not likely to be greater than$100,000. 1 1
En
viro
n
mental Low
Environmental impact from a single major hazard event islikely to be minimal, requiring little to no outside resourcesand support, and/or minimal repair, clean-up, restoration, orpreservation work. 1 1
Es
sential Operatio
n
s Low
Impact less than 24 hours on the ability of the jurisdiction tomeet the essential day-to-day operational demands andneeds of the com munity from a single major hazard event.
1 1
Future Develo
p
ment Low
Future development trends will minimally increaseimpact/consequence of this hazard. 1 1
Climate C
han
ge Medium
Climate Change trends will increase the risk of this hazardand its impacts, but not significantly. 2 2
Strong Winds / DamagingWinds
P
o
p
ulatio
n an
d
Life
Safety
Low
Populations exposed to this hazard are likely to experienceminimal adverse impacts, such as ambulatory injuries. 1 3
Un
derserved/E
q
uity Low
Underserved populations exposed to the hazard are likely toexperience minimal adverse/disproportionate impacts, suchas ambulatory injuries. 1 3
Pro
perty
Damage Medium
More than $500,000 but less than $5 Million in propertydamages is expected from a single major hazard event, ordamages are expected to occur to more than 5% but lessthan 15% of the property value within the jurisdiction. 2 4
Eco
n
o
mic Low
Total economic impact is not likely to be greater than$100,000. 1 1
En
viro
n
mental Low
Environmental impact from a single major hazard event islikely to be minimal, requiring little to no outside resourcesand support, and/or minimal repair, clean-up, restoration, orpreservation work. 1 1

5.6.b
Packet Pg. 298 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Es
sential Operatio
n
s Low
Impact less than 24 hours on the ability of the jurisdiction tomeet the essential day-to-day operational demands andneeds of the com munity from a single major hazard event.
1 1
Future Develo
p
ment Low
Future development trends will minimally increaseimpact/consequence of this hazard. 1 1
Climate C
han
ge Medium
Climate Change trends will increase the risk of this hazardand its impacts, but not significantly. 2 2
Tornado
P
o
p
ulatio
n an
d
Life
Safety
Low
Populations exposed to this hazard are likely to experienceminimal adverse impacts, such as ambulatory injuries. 1 3
Un
derserved/E
q
uity Low
Underserved populations exposed to the hazard are likely toexperience minimal adverse/disproportionate impacts, suchas ambulatory injuries. 1 3
Pro
perty
Damage Low
Less than $500,000 in property damages is expected from asingle major hazard event or less than 5% of the propertyvalue within the jurisdiction. 1 2
Eco
n
o
mic Low
Total economic impact is not likely to be greater than$100,000. 1 1
En
viro
n
mental Low
Environmental impact from a single major hazard event islikely to be minimal, requiring little to no outside resourcesand support, and/or minimal repair, clean-up, restoration, orpreservation work. 1 1
Es
sential Operatio
n
s Low
Impact less than 24 hours on the ability of the jurisdiction tomeet the essential day-to-day operational demands andneeds of the com munity from a single major hazard event.
1 1
Future Develo
p
ment Low
Future development trends will minimally increaseimpact/consequence of this hazard. 1 1
Climate C
han
ge Medium
Climate Change trends will increase the risk of this hazardand its impacts, but not significantly. 2 2
Heavy Rainfall
P
o
p
ulatio
n an
d
Life
Safety
Low
Populations exposed to this hazard are likely to experienceminimal adverse impacts, such as ambulatory injuries. 1 3
Un
derserved/E
q
uity Low
Underserved populations exposed to the hazard are likely toexperience minimal adverse/disproportionate impacts, suchas ambulatory injuries. 1 3
Pro
perty
Damage Low
Less than $500,000 in property damages is expected from asingle major hazard event or less than 5% of the propertyvalue within the jurisdiction. 1 2
Eco
n
o
mic Low
Total economic impact is not likely to be greater than$100,000. 1 1

5.6.b
Packet Pg. 299 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Environmental Low
Environmental impact from a single major hazard event islikely to be minimal, requiring little to no outside resourcesand support, and/or minimal repair, clean-up, restoration, orpreservation work. 1 1
Essential Operations Low
Impact less than 24 hours on the ability of the jurisdiction tomeet the essential day-to-day operational demands andneeds of the community from a single major hazard event. 1 1
Future Development Low Future development trends will minimally increase impact/consequence of this hazard. 1 1Climate Change High Climate Change trends will significantly increase the risk of this hazard and its impacts. 3 3 Heat Wave / ExtremeHeat
Population and LifeSafety Low Populations exposed to this hazard are likely to experience minimal adverse impacts, such as ambulatory injuries. 1 3Underserved/Equity Medium Underserved populations exposed to the hazard are likely toexperience some adverse/disproportionate impacts, such asinjuries requiring acute medical care. 2 6 Property Damage No Impact Little to no property damage is expected from a single major hazard event. 0 0Economic Low Total economic impact is not likely to be greater than $100,000. 1 1Environmental No Impact No environmental impacts from a single major hazard event are likely. 0 0Essential Operations Low Impact less than 24 hours on the ability of the jurisdiction tomeet the essential day-to-day operational demands andneeds of the community from a single major hazard event. 1 1 Future Development Low Future development trends will minimally increase impact/consequence of this hazard. 1 1Climate Change High Climate Change trends will significantly increase the risk of this hazard and its impacts. 3 3

5.6.b
Packet Pg. 300 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 228

4.6.8.8. FEMA NRI Expected Annual Loss Estimates
A hail NRI EAL score, and rating represent a community's relative level of expected building, population, and agriculture loss each year due to hail when compared to the rest of the United States. The EAL score is positively associated to a community’s risk; therefore, a higher EAL score results in a higher Risk Index score. Table 4-168 outlines the hail EAL for Contra Costa County.

Table 4-168. Hail Expected Annual Loss (FEMA National Risk Index) Jurisdiction Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual
Loss
Expected
Annual
Loss
Score
Rating
Contra Costa
County $10,280 $42,961 $1,290 $54,531 40.1 Relatively Low Expected annual loss scores are calculated utilizing an equation that combines values for exposure, annualized frequency, and historic loss ratios (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio).

A strong wind NRI EAL score, and rating represent a community's relative level of expected building, population, and agriculture loss each year due to strong winds when compared to the rest of the United States. The EAL score is positively associated to a community’s risk; therefore, a higher EAL score results in a higher Risk Index score. Table 4-169 outlines the strong wind EAL for Contra Costa County.

Table 4-169. Strong Wind Expected Annual Loss (FEMA National Risk Index) Jurisdiction Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual
Loss
Expected
Annual
Loss
Score
Rating
Contra Costa
County $14,927 $5,591 $76 $20,594 9.4 Very Low
Expected annual loss scores are calculated utilizing an equation that combines values for exposure, annualized frequency, and historic loss ratios (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio).

A tornado NRI EAL score, and rating represent a community's relative level of expected building, population, and agriculture loss each year due to tornadoes when compared to the rest of the United States. The EAL score is positively associated to a community’s risk; therefore, a higher EAL score results in a higher Risk Index score. Table 4-170 outlines the tornado EAL for Contra Costa County.

Table 4-170. Tornado Expected Annual Loss (FEMA National Risk Index) Jurisdiction Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual
Loss
Expected
Annual
Loss
Score
Rating
Contra Costa
County $361,249 $930,045 $213 $1.3 Million 58.8 Relatively Moderate Expected annual loss scores are calculated utilizing an equation that combines values for exposure, annualized frequency, and historic loss ratios (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio).

A riverine flooding NRI EAL score, and rating represent a community's relative level of expected building, population, and agriculture loss each year due to riverine flooding when compared to the rest of the United States. The EAL score is positively associated to a community’s risk; therefore, a higher EAL

5.6.b
Packet Pg. 301 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 229 score results in a higher Risk Index score. Table 4-171 outlines the riverine flooding EAL for Contra Costa County.

Table 4-171. Riverine Flooding Expected Annual Loss (FEMA National Risk Index) Jurisdiction Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual
Loss
Expected
Annual
Loss
Score
Rating
Contra Costa
County $4.0 Million $4.1 Million $291,636 $8.4 Million 96.3 Very High Expected annual loss scores are calculated utilizing an equation that combines values for exposure, annualized frequency, and historic loss ratios (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio).

A heat wave NRI EAL score, and rating represent a community's relative level of expected building, population, and agriculture loss each year due to heat waves when compared to the rest of the United States. The EAL score is positively associated to a community’s risk; therefore, a higher EAL score results in a higher Risk Index score. Table 4-172 outlines the heat wave EAL for Contra Costa County.

Table 4-172. Heat Wave Expected Annual Loss (FEMA National Risk Index) Jurisdiction Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual
Loss
Expected
Annual
Loss
Score
Rating
Contra Costa
County $2.6 Million $485 $18,780 $2.6 Million 96.1 Very High Expected annual loss scores are calculated utilizing an equation that combines values for exposure, annualized frequency, and historic loss ratios (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio).

4.6.8.9. FEMA Severe Weather Risk Index Scores
The hail Risk Index score and rating represent a community's relative risk for hail when compared to the rest of the United States. Table 4-173 illustrates the hail Risk Index rating and score for Contra Costa County.

Table 4-173. Hail Risk Index (FEMA National Risk Index) Jurisdiction Rating Score
Contra Costa County Relatively Low 36.0
Risk Index scores are calculated using an equation that combines scores for Expected Annual Loss due to natural hazards, Social Vulnerability and Community Resilience (Expected Annual Loss x Social Vulnerability / Community Resilience = Risk Index).

The strong wind Risk Index score and rating represent a community's relative risk for strong winds when compared to the rest of the United States. Table 4-174 illustrates the strong wind Risk Index rating and score for Contra Costa County.

5.6.b
Packet Pg. 302 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 230 Table 4-174. Strong Wind Risk Index (FEMA National Risk Index) Jurisdiction Rating Score
Contra Costa County Very Low 6.6
Risk Index scores are calculated using an equation that combines scores for Expected Annual Loss due to natural hazards, Social Vulnerability and Community Resilience (Expected Annual Loss x Social Vulnerability / Community Resilience = Risk Index).

The tornado Risk Index score and rating represent a community's relative risk for tornadoes when compared to the rest of the United States. Table 4-175 illustrates the tornado Risk Index rating and score for Contra Costa County.

Table 4-175. Tornado Wind Risk Index (FEMA National Risk Index) Jurisdiction Rating Score
Contra Costa County Relatively Moderate 55.0
Risk Index scores are calculated using an equation that combines scores for Expected Annual Loss due to natural hazards, Social Vulnerability and Community Resilience (Expected Annual Loss x Social Vulnerability / Community Resilience = Risk Index).

The riverine flooding Risk Index score and rating represent a community's relative risk for riverine flooding when compared to the rest of the United States. Table 4-176 illustrates the riverine flooding Risk Index rating and score for Contra Costa County.

Table 4-176. Riverine Flooding Risk Index (FEMA National Risk Index) Jurisdiction Rating Score
Contra Costa County Very High 96.2
Risk Index scores are calculated using an equation that combines scores for Expected Annual Loss due to natural hazards, Social Vulnerability and Community Resilience (Expected Annual Loss x Social Vulnerability / Community Resilience = Risk Index).

The heat wave Risk Index score and rating represent a community's relative risk for heat waves when compared to the rest of the United States. Table 4-177 illustrates the heat wave Risk Index rating and score for Contra Costa County.

Table 4-177. Heat Wave Risk Index (FEMA National Risk Index) Jurisdiction Rating Score
Contra Costa County Very High 95.7
Risk Index scores are calculated using an equation that combines scores for Expected Annual Loss due to natural hazards, Social Vulnerability and Community Resilience (Expected Annual Loss x Social Vulnerability / Community Resilience = Risk Index).

5.6.b
Packet Pg. 303 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 231 Table 4-178 represents the Severe Weather Total Risk Score for Contra Costa County, based on the Risk Assessment Methodology, as defined in this Plan. For further details on how the probability, extent, vulnerability, and impact factors were calculated, please refer to Table 4-164 through Table 4-167.

Additional details on how the Total Risk Score was calculated can be found in the Risk Assessment Methodology in Section 4.3 of this Plan.

Table 4-178. Severe Weather Total Risk Score
Hazard
Event
Probability Consequence Total Risk
Probability
Factor Extent Vulnerability Impact ConsequenceScore
Total Risk
Score*
Severe Thunderstorm 3 6 16 14 36 54
Strong Winds/Damaging
Winds 3 9 11 16 36 54
Tornado 1 6 6 14 26 16
Heavy Rainfall 3 9 14 15 38 56
Heat Wave/Extreme Heat 3 9 10 15 34 51
Consequence: Sum of all weighted factors.

Extent: Sum of the weighted Extent factors.

Vulnerability: Sum of the weighted Vulnerability factors.

Impact: Sum of the weighted Impact factors.

The Total Risk Score is a measure of Probability and Consequence.

5.6.b
Packet Pg. 304 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 232

4.6.9. Tsunami

4.6.9.1. Description
The term tsunami comes from the Japanese word “harbor wave” because of the devastating effects these waves had on low-lying coastal communities. 274
A tsunami is a series of extremely long waves caused by seismic activity, volcano activity, or landslides.

However, based on records dating back to 1900, over 80% of tsunamis are generated by earthquakes.

Generally, subduction zone earthquakes of magnitude 7.5 or greater at plate boundaries are the most frequent cause of tsunamis. 275 When an earthquake occurs below or near the ocean, waves radiate outward in all directions away from the epicenter, sometimes crossing an entire ocean basin. Additionally, tsunamis also may be generated by submarine and subaerial landslides (which may also be caused by earthquakes), submarine volcanic eruptions, and the collapse of volcanic edifices. 276 Tsunamis, unlike regular waves, move through the entire water column from the ocean floor to the ocean surface. 277 The speed of tsunami depends on the depth of the ocean, but in the deep ocean they can move at over 500 mph. The height or amplitude of a tsunami wave in deep water is generally three (3) feet or less, and thus may not be noticeable to people on ships. As tsunami waves approach land, however, and as the ocean shallows, the waves slow to around 30 to 30 miles per hour but grow significantly in height. 278
Tsunamis are often confused with tidal waves; the three (3) main differences between the two (2) are the following: 279
A tsunami’s water level changes occur much faster, 10 to 15 minutes, than a tidal wave which gradually changes over six (6) to 12 hour periods.

Tsunami waves travel much faster than tidal waves. A tsunami in the deep ocean can move faster than 500 mph while a tidal wave moves at approximately 23 mph.

The incoming waves of a tsunami can be significantly larger than a tidal wave. The world’s largest tidal ranges at 52 feet higher than low tide, while tsunamis can reach 131 feet, striking coastlines with much lower tidal ranges.

Scientists are beginning to better understand another type of tsunami called meteotsunamis. These are large waves (six (6) feet of higher) driven by air pressure disturbances associated with fast-moving weather events (e.g., severe thunderstorms, squalls, other storm fronts). Meteotsunamis are amplified by a shallow continental shelf and inlet or other coastal features. The characteristics of meteotsunamis are very similar to a seismic tsunami and as a result can be confused with storm surge. Although 274 Exploring our Fluid Earth. (n.d.). Tsunamis. Retrieved from https://manoa.hawaii.edu/exploringourfluidearth/physical/coastal-interactions/tsunamis. 275 Pacific Northwest Seismic Network. (n.d.). Frequently Asked Questions. Retrieved from https://pnsn.org/outreach/faq.
276 National Oceanic and Atmospheric Administration. (2023). Tsunamis: Introduction to the Tsunamis. Retrieved from https://www.noaa.gov/jetstream/tsunamis.
277 National Oceanic and Atmospheric Administration. (n.d.). U.S. Department of Commerce. Tsunamis. Retrieved from https://www.noaa.gov/education/resource-collections/ocean-coasts/tsunamis. 278 National Oceanic and Atmospheric Administration. (2023). Tsunamis: Introduction to the Tsunamis. Retrieved from https://www.noaa.gov/jetstream/tsunamis.
279 Exploring our Fluid Earth. (n.d.). Tsunamis. Retrieved from https://manoa.hawaii.edu/exploringourfluidearth/physical/coastal-interactions/tsunamis.

5.6.b
Packet Pg. 305 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 233 scientists have been able to identify atmospheric conditions that produce meteotsunamis, the ability to forecast and issue advisories remains uncertain. 280 Water level analyses and meteorological data in the United States have determined that meteotsunamis occur more often than expected; therefore, these should be included in coastal hazard mitigation planning. 281

4.6.9.2. Hazard Location
Coastal areas of Contra Costa County are vulnerable to tsunamis. Figure 4-24 illustrates Tsunami Hazard Areas within Contra Costa County which represent areas that could be exposed to tsunami hazards during a tsunami event. Areas in yellow are advised to evacuate immediately after an earthquake that lasts a long time or if an official evacuation notification is received. Residents and visitors are advised to evacuate on foot to a green area. The California Tsunami Hazard Area maps and data were developed with the best current available scientific information. They are based on the State of California 2009 Tsunami Inundation Maps for Emergency Planning and enhanced high-resolution, 975-year return period probabilistic tsunami inundation model results.
282
Figure 4-24. Contra Costa County Tsunami Hazard Areas
280 National Oceanic and Atmospheric Administration, National Ocean Service. (n.d.). What is a Meteotsunami? Retrieved from https://oceanservice.noaa.gov/facts/meteotsunami.html. 281 Horillo, J., Cheng, W., Joe, A., and Shang, Y. (2022). Tsunami Inundation Maps Development and Continuation of the Meteotsunami Characterization for the GOM. Retrieved from https://www.tamug.edu/tsunami/Files/report_NTHMP_2022_FY21-web.pdf. 282 California Department of Conservation, California Geological Survey. (2022). California Tsunami Maps.

Retrieved from https://www.conservation.ca.gov/cgs/tsunami/maps.

5.6.b
Packet Pg. 306 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 234

4.6.9.3. Hazard Extent/Intensity
Tsunami intensity is measured by the Papadopoulos and Imamura Scale. In 2001, the 12-point tsunami scale was proposed by Gerassimos Papadopoulos and Fumihiko Imamura. The scale has 12 divisions, and it is consistent with the 12-grade seismic intensity scale. Additionally, the scale is arranged according to the effects on humans, nature, and objects (i.e., vessels), and buildings. 283 Table 4-179 outlines the Papadopoulos and Imamura Tsunami Scale.

Table 4-179. Papadopoulos and Imamura Tsunami Scale
Level Damage Wave Height
(feet) Description
I Not Felt < 3.3
(< 1 meter) --
II Scarcely Felt < 3.3
(< 1 meter)
Felt by a few people on board small vessels. Not
observed on the coast. No effect, no damage.

III Weak < 3.3
(< 1 meter)
Felt by most people on board small vessels. Observed by a few people on the coast. No effect. No damage.

IV Largely Observed < 3.3
(< 1 meter)
Felt by all people on board small vessels and by a few
people on board larger vessels. Observed by most
people on the coast. Few small vessels move slightly
onshore. No damage.

V Strong < 3.3
(< 1 meter)
Felt by all people on board large vessels and observed
by all on the coast. Few people are scared and run to
higher ground. Many small vessels move strongly
onshore, few of the vessels crash into each other or
overturn. Traces of sand layer are left behind in grounds of favorable conditions. Limited flooding of cultivated land. Limited flooding of outdoors facilities (e.g., gardens) of near-shore structures.

VI Slightly Damaging 6.6
(2 meters)
Many people are frightened and run to higher ground.

Most small vessels move violently onshore, or strongly
crash into each other, or overturn. Damage and flooding in a few wooden structures. Most masonry buildings are
able to withstand.

VII Damaging 13.1
(4 meters)
Most people are frightened and try to run to higher
ground. Many small vessels are damaged. Few large
vessels violently oscillate. Objects of various sizes and stability overturn and drift. Sand later and accumulation of pebbles are left behind. Few aquaculture rafts are
washed away. Many wooden structures are damaged,
few are completely destroyed or washed away. Damage
and flooding in few masonry buildings.
283 Intergovernmental Oceanographic Commission. (n.d.). Tsunami Intensity Scale. Retrieved from https://neamtic.ioc-unesco.org/index.php?option=com_content&view=article&id=209&Itemid=442.

5.6.b
Packet Pg. 307 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 235 Level Damage Wave Height
(feet) Description
VIII Heavily Damaging 13.1
(4 meters)
Everyone escapes to higher ground, but some are
washed away. Most small vessels are damaged, and
many are washed away. Few large vessels have moved
ashore or crashed into each other. Big objects are drifted away. There is erosion and littering on the beach.

Extensive flooding. Slight damage in tsunami-control
forests and stop drifts. Many aquaculture rafts are
washed away, a few partially damaged. Most wooden
structures are washed away or demolished. Significant
damage to a few masonry buildings. Most reinforced
concrete buildings sustain damage and flooding is
observed.

IX Destructive 26.2
(8 meters)
Many people are washed away. Most small vessels are
destroyed or washed away. Many large vessels are
violently moved onshore, few are destroyed. There is
erosion and littering on the beach. Local ground
subsidence. Partial destruction in tsunami control forest and stop drifts. Most aquaculture rafts are washed away and many are partially damaged. Significant damage in
many masonry buildings and few reinforced concrete
buildings suffer from major damage.

X Very Destructive 26.2
(8 meters)
General panic. Most people are washed away. Most large
vessels are moved violently onshore, many are destroyed or collided with buildings. Small boulders from the bottom of the sea are moved inland. Cars overturned and drifted.

Oil spill, fires are ignited. Extensive ground subsidence.

Extreme damage in many masonry buildings, and a few
reinforced concrete buildings suffer major damage.

Artificial embankments collapse, port water breaks are
damaged.

XI Devastating 52.5
(16 meters)
Lifelines are interrupted. Extensive fires. Water backwash drifts cars and other objects into the sea. Big boulders from the bottom of the sea are moved inland.

Catastrophic damage in many masonry buildings. Few
reinforced concrete buildings suffer from significant
damage.

X Completely Devastating 105
(32 meters)
Practically all masonry buildings are demolished. Most
reinforced concrete buildings suffer from significant
damage.

4.6.9.4. Warning Time
In the event of a tsunami, NOAA’s Tsunami Warning Centers are responsible for issuing tsunami advisories, watches, and warnings. There are two (2) tsunami warning centers – the Pacific Tsunami Warning Center (PTWC) and the National Tsunami Warning Center (NTWC) which is responsible for the continental United States, Alaska, and Canada. Table 4-180 outlines the four (4) levels of tsunami alerts issued by the NTWC.
284
284 National Oceanic and Atmospheric Administration. (2017). User’s Guide for the Tsunami Warning System in the U.S. National Tsunami Warning Center Area-of-Responsibility. Retrieved from https://www.tsunami.gov/operations/opsmanual.pdf.

5.6.b
Packet Pg. 308 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 236 Table 4-180. National Tsunami Warning Center Alerts
Type Definition
Tsunami Information
Statement
Issues to inform that an earthquake has occurred, or that a tsunami warning, watch or advisory has been issued for another section of the ocean. In most cases, information statements are issued to indicate there is no threat of a destructive basin wide tsunami and to prevent unnecessary evacuations as the earthquake may have been felt in coastal areas. Information statements may indicate for distant regions that a large event is being evaluated and could be upgraded to a warning, advisory, or watch.

Tsunami Watch
Issued to alert emergency management officials and the public of an event which may later impact the watch area. The watch area may be upgraded to a warning or advisory (or canceled) based on updated information and analysis. Therefore, emergency management officials and the public should prepare to take action.

Watches are normally issued based on seismic information without confirmation that a destructive tsunami is underway.

Tsunami Advisory
Issued when a tsunami with the potential to generate strong currents or waves dangerous to those in or very near the water is imminent, expected, or occurring.

The threat may continue for several hours after initial arrival, but significant inundation is not expected for areas under an advisory. Appropriate actions to be taken by local officials may include closing beaches, evacuating harbors and marinas, and the repositioning of ships to deep waters when there is time to safely do so. Advisories are normally updated to continue the advisory, expand/contract affected areas, upgrade to a warning, or cancel the advisory.

Tsunami Warning
Issued when a tsunami with the potential to generate widespread inundation is imminent, expected, or occurring. Warnings alert the public that dangerous coastal flooding accompanied by powerful currents is possible and may continue for several hours after initial arrival. Warnings alert emergency management officials to take action for the entire tsunami hazard zone. Appropriate actions to be taken by local officials may include the evacuation of low-lying coastal areas, and the repositioning of ships to deep waters when there is time to safely do so. Warnings may be updated, adjusted geographically, downgraded, or canceled. To provide the earliest possible alert, initial warnings are normally based only on seismic information.

4.6.9.5. Probability and Frequency
The probability of occurrence for a tsunami in Contra Costa County is low because a significant hazard event is likely to occur within 100 years.

Probability of Future Hazard Events
The tsunami annualized frequency value represents the average number of recorded tsunami hazard occurrences, in event days, per year over the period of record (222 years). Table 4-181 outlines the annualized frequency for tsunami, based on FEMA NRI data, for Contra Costa County.

Table 4-181. Tsunami Annualized Frequency (FEMA National Risk Index) Location Events on Record
(1800 – 2021)
Annualized Frequency
Contra Costa County 5 0.0 events per year
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year.

5.6.b
Packet Pg. 309 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 237

4.6.9.6. Past Events
Contra Costa County has not been impacted by a tsunami. However, NCEI has reported one (1) tsunami event between 1950 and 2023 within the San Francisco Bay area, listed in Table 4-182 The evening of March 10, 2011, a magnitude 8.9 earthquake struck near the coast of Honshu, Japan. The earthquake generated a tsunami significantly affecting California on March 11, 2011, damaging coastal areas in Santa Cruz and Monterey counties.
285
Table 4-182. Tsunami Events (1950 – 2023)
Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 3/11/2011 09:12 Tsunami 0 0 50.00K 0.00K TOTAL 0 0 50.00K 0.00K

4.6.9.7. Vulnerability and Impacts
Life Safety and Health: A tsunami poses significant threats to the life safety and health of the population within shoreline areas in the northwest portion of the County which includes the unincorporated areas of Bay Point, North Richmond, and other western areas, and the cities of Richmond, Pinole, Hercules, and Martinez, as illustrated in Figure 4-24. These areas are subject to tsunami inundation as illustrated in the California Tsunami Hazard Areas Maps. Immediate dangers from a tsunami involve primarily that of drowning and traumatic injury due to debris during the wave. A tsunami contaminates water and food supplies, and the lack of clean essentials can cause significant injury or death. Furthermore, contamination from tsunami increases the risk of infection. 286
In the event of a tsunami, the underserved and at-risk populations within tsunami inundation areas face unique vulnerabilities and impacts. These groups include, but are not limited to, households in poverty, individuals experiencing homelessness, the elderly population including those with access and functional needs, population without access to lifelines, and individuals with limited English proficiency. 287
Households in Poverty: Includes those with an income at or below $24,300 for a household of four (4). This population is more likely to live in low lying areas within tsunami inundation areas and the 100-year floodplain, and dwellings may not be waterproofed. In Contra Costa County, the households in poverty along the coastline of North Richmond to Port Costa are vulnerable to tsunamis.

Individuals Experiencing Homelessness: Includes those who do not have a permanent home, including those who live in their vehicles or temporary shelters. This population is uniquely vulnerable to tsunamis because most of the homeless encampments are located along the coastal cities near and within coastal flood areas in the County. Therefore, a tsunami can damage or destroy these encampments and other homeless facilities located within the coastline resulting 285 National Centers for Environmental Information. (2011). Storm Events Database. https://www.ncdc.noaa.gov/stormevents/eventdetails.jsp?id=288765. 286 Centers for Disease Control. (n.d.). Health Effects of Tsunamis. Retrieved from https://www.cdc.gov/disasters/tsunamis/healtheff.html.
287 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.

5.6.b
Packet Pg. 310 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 238 in additional hardship for this population. In 2024, there are 2,843 people experiencing homelessness in Contra Costa County, an 18.5% increase from 2023. 288
Senior (65 years old and over): The elderly population (i.e., seniors), especially those with access and functional needs, may have physical limitations that make it harder to evacuate in the event of an emergency, such as a tsunami. Furthermore, this population may lack access to social connections and community support that can assist in preparing for and responding to emergency events, evacuating, improving home resiliency, managing medical needs, and locating support services.

Individuals Without Access to Lifelines: Includes individuals who do not have access to basic technology or services (e.g., transportation, modern communication). This population is vulnerable because not having access to these can create barriers to prepare and respond to emergency events (e.g., tsunami evacuation order), may be unable to evacuate in a timely manner, and may become isolated if transit services are not operating. For example, this population may be unaware of a tsunami evacuation order and may be unable to evacuate in a timely manner.

Table 4-183 summarizes the vulnerable and at-risk population for tsunamis in Contra Costa County.

Table 4-183. Vulnerability and At Risk Population
Category Estimate Percent
Households in Poverty289 7,600 12.0%
Low Income Households290 25,340 41.0%
Homeless Population291 2,843 0.2%
65 Years and Over292 201,136 17.4%
Seniors (65 years and over) Living
Alone293 45,672 22.7%
288 Contra Costa Health. (2024). Health, Housing, and Homelessness Data Reports (Point-in-Time Count).

Retrieved from https://www.cchealth.org/services-and-programs/homeless-services/data. 289 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.
290 Ibid.
291 Contra Costa Health. (2024). Health, Housing, and Homelessness Data Reports (Point-in-Time Count).

Retrieved from https://www.cchealth.org/services-and-programs/homeless-services/data. 292 United States Census Bureau. (2022). DP05: Demographics and Housing Estimates (2022: ACS 1-Year Estimates Data Profiles). Retrieved from
https://data.census.gov/table/ACSDP1Y2022.DP05?g=050XX00US06013. 293 United States Census Bureau. (2022). DP02: Selected Social Characteristics in the United States (2022: ACS 1-Year Estimates Data Profiles). Retrieved from
https://data.census.gov/table/ACSDP1Y2022.DP02?g=050XX00US06013.

5.6.b
Packet Pg. 311 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 239 Category Estimate Percent
Households Without Vehicle294 8,872 1.6%
Spanish Spoken at Home295 204,442 18.7%
Speak English “Less than very
well”296 158,965 38.2%
Language Other than English297 416,505 38.0%
Table 4-187 outlines the vulnerability of the total population exposed to tsunamis, and Table 4-188 outlines the tsunami impacts to population and life safety, underserved/equity population, and essential operations, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Property Damage and Critical Infrastructure: Roads are the primary resource for evacuation to higher ground before and during a tsunami event. Roads also can serve as flood control facilities for low depth, low velocity floods by acting as levees or berms and diverting or containing flood flows. The major roads in the planning area that intersect tsunami inundation areas are Eastshore Freeway, John T. Knox Freeway, and Richmond Parkway. These are major roads that may be impacted by a tsunami, based on exposure (they are evacuation routes for tsunami events). Evacuation routes are identified in emergency response plans in effect within the planning area.

In Contra Costa County, there is a range from the large, state-owned bridges that carry interstate freeways, to locally owned bridges that carry rural roads and pedestrians over small creeks. Countywide, there are over 400 bridges where approximately 80 are owned by the County and 160 are owned by Caltrans. There are 26 bridges that are within the 100-year flood zone and could potentially be affected by a tsunami. Some of these bridges are located in low lying areas that could become flooded during a tsunami event if located by the coastline. Additionally, flood control infrastructure (i.e., levees, dikes, and drainage channels), meant to prevent the creeks, Delta, and other bodies of water from overflowing and causing floods could fail during a tsunamis and cause flooding in these areas. Although the Contra Costa County Flood Control District is responsible for local flood control projects, many of these levees and drainage facilities in the Delta region of the County are privately owned and operated. Portions of Interstate 80 and 680, and State Route 4, and the Benecia-Martinez Bridge and the Carquinez Bridge, which are major transportation routes to the area, may be exposed to tsunami flooding.

Armtrak, freight line, and the BART within coastal areas may also be exposed to tsunami flooding. There are three (3) standard rail lines that run through Contra Costa County which are operated by Union Pacific, Burlington Northern Santa Fe, and Richmond Pacific Railroad Corporation. These run along the western, northern, and eastern boundaries of the County, along Interstate 80, State Route 4, and Byron Highway. The aforementioned rail lines are used for freight trains; however, the Capitol Corridor commuter train runs along the Union Pacific railway. Additionally, the BART operates its own separate rail lines used exclusively for public transit. Two (2) BART rail lines are located in the County – one beginning in Richmond and heading south toward Berkeley and another one in the central part of the County extending from the City of Orinda to the City of Antioch. Flooding from a tsunami can cause damage to the tracks and result in the system to completely shutting down. 294 United States Census Bureau. (2022). S0801: Commuting Characteristics by Sex. Retrieved from https://data.census.gov/table/ACSST1Y2022.S0801?g=050XX00US06013. 295 United States Census Bureau. (2022). S1601: Language Spoken at Home (2022: ACS 1-Year Estimates Subject Tables). Retrieved from https://data.census.gov/table/ACSST1Y2022.S1601?g=050XX00US06013. 296 Ibid.
297 Ibid.

5.6.b
Packet Pg. 312 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 240 Three (3) wastewater treatment plants – Rodeo sewage treatment plans, West Contra Costa Wastewater, and Mt. View Sanitary District – are within low lying or coastal flooding areas. During a tsunami event, flooding to these facilities can exacerbate wet weather flows into the treatment plants and if the pumps and control panels are not waterproofed or salt resistant, the system can fail. Additionally, if the Delta levee fails the Mokelumne Aqueduct could be exposed to coastal flooding and the Contra Costa Canal and the Clifton Court Forebay are also within the coastal flooding area. In the event that these levees fail during a tsunami event, these water and wastewater infrastructure would also fail resulting in the contamination of freshwater, reducing the availability of drinking and agricultural water.

In Contra Costa County, there are approximately 61 industrial buildings within the coastal flooding areas.

Tsunamis can cause serious damage to industrial structures and increase the potential of a hazardous materials release that can contaminate soil, water, and air in the surrounding areas. 298
There are a total of 554 critical assets (i.e., schools, nursing homes, fire stations, police stations, and hospitals) throughout the County and none are located within the tsunami hazard areas. Table 4-184 provides a breakdown of critical assets that are located within tsunami hazard areas in Contra Costa County.

Table 4-184. Critical Assets Vulnerable to Tsunami
Asset Estimate Percent
(of total assets)
Schools (public schools, private schools) 0 0.0%
Nursing Homes 0 0.0%
Fire Stations 0 0.0%
Police Stations 0 0.0%
Hospitals 0 0.0%
Table 4-187 outlines the total property value exposed to tsunamis and how the changes in development in the past five (5) years, have affected the vulnerability of the community to tsunamis. Table 4-188 outlines the tsunami impacts on total property damage, potential future development, and the economy, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Environment: Inundation of water by tsunami and introduction of foreign debris could be hazardous to the environment. All wildlife inhabiting the inundated area is exposed. The vulnerability of aquatic habitat and associated ecosystems would be highest in low lying areas close to the southern portion of San Francisco Bay coastline. Tsunami waves can carry destructive debris and pollutants that can devastate the environment. Millions of dollars spent on habitat restoration and conservation in Contra Costa County could be destroyed as a result of one significant tsunami. There are currently no tools available to measure these impacts. However, the potential financial impact of a tsunami event on the environment could equal or exceed the impact on property. Community planners and emergency managers should take this into account when preparing for the tsunami hazard and considering future development.

Additionally, industrial buildings located within the coast are vulnerable to tsunamis and damage to these 298 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.

5.6.b
Packet Pg. 313 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 241 structures can lead to severe environmental concerns due to the potential of hazardous materials released to the soil, water, and air.299
Table 4-188 outlines tsunami impacts on the environment and economy, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Changes in Development and Impact of Future Development: Construction and development on coastal areas of San Francisco Bay is strictly regulated. There has been minimal development in these areas of Contra Costa County since the Hazard Mitigation Plan was completed. Expected future development will be closely managed with the County through land use ordinances. Due to the increasing risk from tsunamis due to sea level rise, development in the coastal zone will be minimized.

Table 4-187 outlines how the changes in development in the past five (5) years have affected the vulnerability of the community to tsunamis. Table 4-188 outlines the tsunami impacts on potential future development, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Effects of Climate Change in Severity of Impacts: Sea level rise due to climate change is making coastal communities more vulnerable to tsunamis because a rise in sea level can exacerbate tsunamis, even small ones, which can travel further inland. A warming climate can increase the risk of underwater and above ground landslides which can generate tsunamis on impact when the landslide enters the water or when water is rapidly moving due to an underwater landslide. Although the correlation between climate change, volcano activity, and earthquakes is not fully understood, experts believe that melting ice can also increase volcanic and earthquake activity, both of which can produce tsunamis. This could be due to isostatic rebound, also known as post-glacial rebound, which is the rise of land masses that were depressed by the weight of ice sheets during the last ice age. 300 As ice continues to melt, stress to the Earth’s crust changes potentially increasing the risk of volcano activity. Furthermore, the weight of ice suppresses fault movement and earthquake, but when the weight is removed faults can become unstable. 301
Table 4-188 outlines the climate change impacts to tsunamis in Contra Costa County, as outlined in the risk assessment methodology in Section 4.3 of this Plan. 299 Ibid.
300 National Snow and Ice Data Center. (n.d.). Cryosphere Glossary: Isostatic Rebound. Retrieved from https://nsidc.org/learn/cryosphere-glossary/isostatic-rebound. 301 Cunneen, J. (2022). 5 Ways Climate Change Increases the Threat of Tsunamis, From Collapsing Ice Shelves to Sea Level Rise. Retrieved from https://theconversation.com/5-ways-climate-change-increases-the-threat-oftsunamis-from-collapsing-ice-shelves-to-sea-level-rise-175247.

5.6.b
Packet Pg. 314 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Tsunami Low Significant hazard event is likely to occur within 100 years. 1 N/A Tsunami
Extent/Intensity Low Historical and/or probabilistic models/studies for this hazard indicate the possibility of a low-intensity incident. 1 3Catastrophic Low Catastrophic hazard event is likely to occur at least once in 51 or more years. 1 3 Sea Level Rise
Population Exposure Low 14% or less of the population is exposed to the hazard. 1 3Property Exposure Low 9% or less of the total assessed property value is exposed to a hazard. 1 2Changes inDevelopment Low Changes in development have increased thevulnerability/exposure of the community to the hazard by 4%or less. 1 1 Sea Level Rise
Population and LifeSafety Low Populations exposed to this hazard are likely to experience minimal adverse impacts, such as ambulatory injuries. 1 3Underserved/Equity Medium Underserved populations exposed to the hazard are likely toexperience some adverse/disproportionate impacts, such asinjuries requiring acute medical care. 2 6 Property Damage Medium
More than $500,000 but less than $5 Million in propertydamages is expected from a single major hazard event, ordamages are expected to occur to more than 5% but lessthan 15% of the property value within the jurisdiction. 2 4 Economic High Where the total economic impact is likely to be greater than $10 Million. 3 3

5.6.b
Packet Pg. 315 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Environmental High
Environmental impact from a single major hazard event islikely to be significant, requiring extensive outside resourcesand support; and/or repair, clean-up, restoration, and/orpreservation work. 3 3
Essential Operations Medium
Impact between 24 and 72 hours on the ability of thejurisdiction to meet the essential day-to-day operationaldemands and needs of the community from a single majorhazard event. 2 2
Future Development Low Future development trends will minimally increase impact/consequence of this hazard. 1 1Climate Change Low Climate Change trends will minimally increase the risk of this hazard and its impacts. 1 1

5.6.b
Packet Pg. 316 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 244

4.6.9.8. FEMA NRI Expected Annual Loss Estimates
A tsunami NRI EAL score, and rating represent a community's relative level of expected building and population loss each year due to tsunamis when compared to the rest of the United States. The EAL score is positively associated to a community’s risk; therefore, a higher EAL score results in a higher Risk Index score. Table 4-189 outlines the tsunami EAL for Contra Costa County.

Table 4-189. Tsunami Expected Annual Loss (FEMA National Risk Index) Jurisdiction Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual
Loss
Expected
Annual
Loss
Score
Rating
Contra Costa
County $2,012 $38,659 N/A $40,671 82.0 Very High
Expected annual loss scores are calculated utilizing an equation that combines values for exposure, annualized frequency, and historic loss ratios (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio).

4.6.9.9. FEMA Tsunami Risk Index Scores
The tsunami Risk Index score and rating represent a community's relative risk for tsunamis when compared to the rest of the United States. Table 4-190 illustrates the tsunami Risk Index rating and score for Contra Costa County.

Table 4-190. Tsunami Risk Index (FEMA National Risk Index) Jurisdiction Rating Score
Contra Costa County Relatively High 66.2
Risk Index scores are calculated using an equation that combines scores for Expected Annual Loss due to natural hazards, Social Vulnerability and Community Resilience (Expected Annual Loss x Social Vulnerability / Community Resilience = Risk Index).

5.6.b
Packet Pg. 317 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 245 Table 4-191 represents the Tsunami Total Risk Score for Contra Costa County, based on the Risk Assessment Methodology, as defined in this Plan. For further details on how the probability, extent, vulnerability, and impact factors were calculated, please refer to Table 4-185 through Table 4-188.

Additional details on how the Total Risk Score was calculated can be found in the Risk Assessment Methodology in Section 4.3 of this Plan.

Table 4-191. Tsunami Total Risk Score
Hazard
Event
Probability Consequence Total Risk
Probability
Factor Extent Vulnerability Impact ConsequenceScore
Total Risk
Score*
Tsunami 1 6 6 22 34 20
Consequence: Sum of all weighted factors.

Extent: Sum of the weighted Extent factors.

Vulnerability: Sum of the weighted Vulnerability factors.

Impact: Sum of the weighted Impact factors.

The Total Risk Score is a measure of Probability and Consequence.

5.6.b
Packet Pg. 318 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 246

4.6.10. Wildfire

4.6.10.1. Description
Wildfires are unplanned fires that occur in wildlands (e.g., forest, rangelands, or grasslands) and they are nearly impossible to prevent and difficult to control. These extreme events are common in the western United States, usually occurring during the summer and fall. 302 Free-burning fires can occur whenever combustible fuel (e.g., grasses, shrubs, trees, dead leaves) in the presence of oxygen at an extremely high temperature becomes gas (flames are the visual indicator of heated gas). Smoldering fires can occur with lower temperature heat sources and, over time, can reach ignition temperature when rapid fire growth occurs. Wildfires can be ignited by natural occurrences (e.g., lightning strike) or by human causes (e.g., unattended campfire, debris burning, or arson). In 2022, 87% of wildfires in the United States were ignited by humans; meaning that they could have been prevented. 303 However, weather conditions and topography determine the behavior of wildfire. Wind, high temperatures, and low humidity create a perfect environment for a wildfire to grow; furthermore, flames burn faster when they are moving uphill versus downhill.

Wildfires can be classified in three (3) different classes, listed in Table 4-192, and it is not uncommon to have all three (3) types of fire.
304
Table 4-192. Types of Wildfires
Type Description
Ground Fires
Mostly burn in decayed roots below ground and in the duff later which is comprised by dead plant materials (e.g., leaves, bark, needles, and twigs). Ground fires are sustained by glowing combustion (without flames) and go undetected for a long period of time because the produce little to no smoke and spread slowly.

Surface Fires
Burn loose needles, moss, lichen, herbaceous vegetation, shrubs, small trees, and saplings that are located at or near the surface of the ground, mostly by flaming combustion. Surface fires can grow in intensity to scorch or consume the forest canopy, a characteristic that is seen in crown fires depending on the following – amount of surface fuel (high), fuel moisture content (low), slope and/or wind speed (high), resultant surface flame length (high), height of the base of tree crowns (small), and density and compactness of tree crowns (tight).

Crown Fires
Usually ignited by a surface fire, crown fires burn forest canopy fuels, which include live and dead foliage/ branches, lichens in trees, and tall shrubs that lie well above the surface fuels. Crown fires can be passive (involve the burning of individual trees or small groups of trees, often called torching) or active (also referred to as running crown fires, present a solid wall of flame from the surface through the canopy fuel layers as seen in the photo below.

Wildfires are a necessary part of the natural ecosystem in California, but they become a hazard when they extend out of control into developed areas, resulting in loss of property, injuries, or the loss of life.

The wildfire risk in the United States has increased in the last few decades with the increasing encroachment of residences and other structures into the wildland environment and the increasingly large number of people living in wildland areas.
302 United States Department of Agriculture. (n.d.). Wildfire. Retrieved from https://www.climatehubs.usda.gov/taxonomy/term/398.
303 United States Forest Service. (n.d.). About Wildfires. Retrieved from https://smokeybear.com/en/aboutwildland-fire. 304 Northwest Fire Science Consortium. (n.d.). What are Types of Fire? Retrieved from https://www.nwfirescience.org/sites/default/files/publications/Types%20of%20Fire.pdf.

5.6.b
Packet Pg. 319 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 247 The Contra Costa County Fire Protection District (CCCFPD) provides fire prevention, suppression, and emergency medical response for advanced and basic life support to nine (9) cities and much of the unincorporated areas the central and western Contra Costa County The CCCFPD operates 30 stations throughout its jurisdictional area and has a staff of over 250 uniformed personnel. 305

4.6.10.2. Hazard Location
In Contra Costa County, 192,192 acres are classified as very high, high, or moderate fire hazard zones (i.e., Fire Hazard Severity Zones). 306 The geography, weather patterns, and vegetation in the East Bay area provide ideal conditions for recurring wildfires. Especially vulnerable are the East Bay Hills in Lamorinda (which includes Lafayette, Moraga, and Orinda). Parts of Walnut Creek, including the area surrounding Rossmoor, Clayton, the Danville/San Ramon area, and the San Pablo - El Cerrito, El Sobrante area are vulnerable to wildfires.

Additionally, peat fires, which occur in the Sacramento/San Juaquin Delta on reclaimed land east of the City, can result in heavy smoke. This can affect air quality and result in hazardous atmospheric particulate matter. Figure 4-25 illustrates the Fire Hazard Severity Zones (FHSZ) in the State Responsibility Area (SRA) and Figure 4-26 illustrates the Wildland Urban Interface areas in Contra Costa County.

Figure 4-25. Contra Costa County Fire Hazard Severity Zones 305 Contra Costa County Fire Protection District. (n.d.). Station Addresses. Retrieved from https://cccfpd.org/station-address/.
306 State of California and the Department of Forestry and Fire Protection. (2023). State Responsibility Area Fire Hazard Severity Zones: Contra Costa County. Retrieved from https://osfm.fire.ca.gov/what-we-do/communitywildfire-preparedness-and-mitigation/fire-hazard-severity-zones/fire-hazard-severity-zones-maps-2022.

5.6.b
Packet Pg. 320 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 248 Figure 4-26. Contra Costa County Wildland-Urban Interface

4.6.10.3. Hazard Extent/Intensity
Wildfires are considered a natural and necessary component of wildland ecology. As a result, wildfires are not considered a major hazard unless their movement threatens lives, homes, communities, critical infrastructure, and natural and cultural resources.

CAL FIRE modeled and mapped wildfire hazard zones using a science based and field tested computer model that designates a hazard score based on the factors that influence fire likelihood and fire behavior.

Ultimately, three (3) levels of FHSZ were identified – moderate, high, and very high.

The model also is based on frequency of fire weather, ignition patterns, and expected rate-of spread. It accounts for flying ember production, which is the principal driver of the wildfire hazard in densely developed areas. A related concern in built-out areas is the relative density of vegetative fuels that can serve as sites for new spot fires within the urban core and spread to adjacent structures. The model refines the zones to characterize fire exposure mechanisms that cause ignitions to structures. Significant land-use changes need to be accounted for through periodic model updates. Figure 13-1 shows the FHSZ mapping for Contra Costa County. Table 13-2 lists the total area mapped in each zone. Most of the mapped zones are in the unincorporated county.

Even if a wildfire is not occurring within Contra Costa County, wildfire smoke can affect the visibility and air quality of the region. Wildfire smoke is a mix of gases and fine particles from burning vegetation, building materials, and other materials. The Air Quality Index (AQI) is used by the United States

5.6.b
Packet Pg. 321 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 249 Environmental Protection Agency (EPA) to report air quality. The AQI is divided into six (6) categories, listed in Table 4-193, each of which corresponds to a different level of health concern.

Table 4-193. Air Quality Index for Ozone and Particle Pollution Daily AQI
Color
Levels of
Concern
Values of
Index Description of Air Quality
Green Good 0 to 50 Air quality is satisfactory, and air pollution poses little or no risk.

Yellow Moderate 51 to 100
Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually
sensitive to air pollution.

Orange Unhealthy for
Sensitive Groups 101 to 150 Members of sensitive groups may experience health effects. The general public is less likely to be affected.

Red Unhealthy 151 to 200
Some members of the general public may experience
health effects; members of sensitive groups may
experience more serious health effects.

Purple Very Unhealthy 201 to 300 Health alert. The risk of health effects is increased for everyone.

Maroon Hazardous 301 or higher Health warning of emergency conditions. Everyone is more likely to be affected.

EPA establishes an AQI for five (5) major air pollutants regulated by the Clean Air Act. Each of these pollutants has a national air quality standard set by EPA to protect public health - ground-level ozone, particle pollution (also known as particulate matter, including PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide.

4.6.10.4. Warning Time
When weather conditions are conducive to wildfire ignition, the NWS local Forecast Office issues a series of advisories. Table 4-194 outlines the fire advisories issued by NWS as conditions warrant. 307 Table 4-194. National Weather Service Fire Advisories
Type Definition
Fire Weather Watch
Issued to alert land managers and the public that upcoming weather conditions (e.g., combination of strong winds and low humidity, dry and unstable air mass, and/or lightning) could result in extensive wildland fire occurrence or extreme fire behavior. It is issued when critical fire weather conditions are possible but not imminent or occurring.

Red Flag Warning
Issued by NWS, in conjunction with land management agencies, to alert land managers to an ongoing or imminent critical fire weather pattern (e.g., combination of strong winds and low humidity, dry and unstable air mass, and/or lightning). It is issued when fire conditions are ongoing or expected to occur shortly.

Extreme Fire
Behavior
Issued when a wildfire is likely to run out of control. It is often hard to predict because fires tend to behave erratically and sometimes dangerously. To issue this alert, one (1) or more of the following criteria must be met – moving fast (i.e., high rate of spread), prolific crowning and/or spotting, presence of fire whirls, and/or strong convection column.

4.6.10.5. Probability and Frequency
The probability of occurrence for a wildfire in Contra Costa County is medium because a significant hazard event is likely to occur every 25 years. However, isolated and lower-impact events occur annually. 307 National Weather Service. (n.d.). Understanding Wildfire Warnings, Watches and Behavior. Retrieved from https://www.weather.gov/safety/wildfire-ww.

5.6.b
Packet Pg. 322 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 250 From 2010 to 2022, there were 24 wildfires in Contra Costa County 308, most burning over 100 acres each. Some burned considerably more acreage, most notably the 2020 Santa Clara Unit Complex Fire, which burned 396,824 acres in total (3,305 acres in Contra Costa County). As noted below, NCEI has reported 18 wildfire events between 1950 and 2023 in Contra Costa County. While this is fewer than the number reported by the County, wildfires remain a significant threat.

Probability of Future Hazard Events
Because of climate change, fire activity is projected to increase where development expands in the WUI, in addition to the dry hills around Mount Diablo.

The wildfire annualized frequency value represents the modeled frequency of wildfire hazard occurrences, in event days, per year. Table 4-195 outlines the annualized frequency for wildfire, based on FEMA NRI data, for Contra Costa County.

Table 4-195. Wildfire Annualized Frequency (FEMA National Risk Index) Location Events on Record
(2021 Dataset)
Annualized Frequency
Contra Costa County N/A 0.306% chance per year
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year.

4.6.10.6. Past Events
NCEI has reported 18 wildfire events, listed Table 4-196, between 1950 and 2023 in Contra Costa County. None of its wildfires have caused sufficient damage to trigger a state or federal disaster declaration.

Table 4-196. Wildfire Events (1950 – 2023)
Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 5/20/2022 11:00 Wildfire 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 7/11/2021 08:22 Wildfire 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 9/1/2020 00:00 Wildfire 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 8/16/2020 04:00 Wildfire 0 6 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 7/20/2020 13:15 Wildfire 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 7/6/2020 13:00 Wildfire 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 7/4/2020 12:28 Wildfire 0 0 0.00K 0.00K
308 Contra Costa County. (2023). Public Review Draft Contra Costa County 2045 General Plan – Health and Safety Element. Retrieved from https://envisioncontracosta2040.org/wpcontent/uploads/2024/02/Chapter_9_Health-and-Safety-Element.pdf.

5.6.b
Packet Pg. 323 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 251 Location County /
Zone State Date Time Type Death Injury PropertyDamage
Crop
Damage

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 7/4/2020 22:00 Wildfire 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 6/6/2020 16:00 Wildfire 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 10/27/2019 07:50 Wildfire 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 10/27/2019 10:30 Wildfire 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 10/27/2019 13:00 Wildfire 0 0 0.00K 0.00K

SAN FRANCISCO

BAY SHORELINE
(ZONE)
San Francisco
Bay Shoreline CA 10/27/2019 13:45 Wildfire 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 10/27/2019 15:00 Wildfire 0 0 0.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 10/24/2019 20:40 Wildfire 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 10/10/2019 00:00 Wildfire 0 0 0.00K 0.00K

EAST BAY

INTERIOR

VALLEYS (ZONE)
East Bay
Interior Valleys CA 8/7/2019 12:00 Wildfire 0 0 5.00K 0.00K

EAST BAY HILLS

AND THE DIABLO

RANGE (ZONE)
East Bay Hills
And The
Diablo Range
CA 6/11/2019 11:34 Wildfire 0 0 5.00K 0.00K
TOTAL 0 6 10.00K 0.00K
Figure 4-27 illustrates the perimeters of wildfires from 1950 to 2022. These are areas that have previously burned, regardless of their location within or outside of a Fire Hazard Severity Zone, are likely to burn again.

5.6.b
Packet Pg. 324 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 252 Figure 4-27. Contra Costa County Historic Wildfire Perimeters

4.6.10.7. Vulnerability and Impacts
Life Safety and Health: There have been no recorded incidents of loss of life from wildfires within the planning area in the last several decades. Given the immediate response times to reported fires, the likelihood of injuries and casualties is minimal; therefore, injuries and casualties were not estimated for the wildfire hazard. Even so, wildfire risk and activity in the planning area are expected to significantly increase due to climate change. The 2024 Climate Action Plan (draft version) identified the increased risk for landslides and floods because of wildfires.

The entire population within a wildfire hazard area is vulnerable to wildfires and the entire County population is vulnerable to wildfire smoke. However, the underserved and at risk population face unique vulnerabilities and impacts as a result of wildfires and wildfire smoke. These groups include, but are not limited to, children, households in poverty, individuals experiencing homelessness, population living on single access roads, people with chronic illnesses, individuals with limited English proficiency, individuals without access to lifelines, and elderly.

Children (under 10 years old): The younger population will be susceptible to pollution from poor air quality and wildfire because they spend more time outside, have a weaker immune system, and a child’s respiratory system is still developing which makes them more vulnerable. In Contra Costa County, there are approximately 130,099 (11.2%) children under 10 years old as of 2022.309 The highest concentration of children lives in parts of the cities of Concord, Richmond, Pittsburg, Brentwood, and San Ramon.
309 United States Census Bureau. (2022). S0101: Age and Sex (2022: ACS 1-Year Estimates Subject Tables).

Retrieved from https://data.census.gov/table/ACSST1Y2022.S0101?g=050XX00US06013.

5.6.b
Packet Pg. 325 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 253 Households in Poverty: Includes those with an income at or below $24,300 for a household of four (4) people. This population may have financial limitations or neighborhood characteristics that makes it difficult to maintain defensible space in fire prone areas; therefore, making them more susceptible to wildfire damage. Some of these homes are located within the WUI.

Individuals Experiencing Homelessness: Includes those who do not have a permanent home, including those who live in their vehicles or temporary shelters. This population may face significant health issues that can reduce lung function, pneumonia, asthma, and cardiovascular issues. Furthermore, these individuals may not have adequate access to healthcare. In Contra Costa County, homeless encampments located near Bay Point, Lafayette, Alamo, El Sobrante and other WUI areas may be in danger of being burned during a wildfire.

Individuals Living on Single Access Roads: Includes the population living in areas with a single route in and out (i.e., accessible via one (1) roadway) of the neighborhood or area. This population can become isolated from the community and emergency services in the event that the only route is destroyed or blocked due to a wildfire. In Contra Costa County, several neighborhoods and communities in the Delta, and in the hillside areas in the central and western side of the County, are only accessible via one (1) roadway.

Individuals with Chronic Illnesses: Includes those that have long term or permanent health conditions that can be exacerbated by wildfire smoke (e.g., cardiovascular disease, respiratory conditions, diabetes, cerebrovascular diseases). A wildfire that is not within Contra Costa County can impact the area with wildfire smoke, even when the wildfire is taking place thousands of miles away.

People with Limited English Proficiency: This group includes those that speak English “less than very well”, per the United States Census Bureau definition. In Conta Costa County, 158,965 people (38.2%) have limited English proficiency (i.e., speak English “less than very well”). This population is more likely to live in neighborhoods that make it difficult to maintain defensible space that can protect their homes from wildfire. Additionally, individuals with limited English proficiency may have limited access to evacuation information and resources designed to prevent or mitigate wildfire risk due to language or cultural differences. Other languages spoken in the County are primarily Spanish, Mandarin, Cantonese, Tagalog, and Persian. Other than English, the most commonly spoken language in Contra Costa County is Spanish (18.7%). The higher proportion with limited English proficiency occurs in the cities of Richmond, Concord, and San Pablo.

Individuals Without Access to Lifelines: Includes individuals who do not have access to basic technology or services (e.g., transportation, modern communication). This population is vulnerable because not having access to these can create barriers to prepare and respond to emergency events (e.g., wildfire), may be unable to evacuate in a timely manner, and may become isolated if transit services are not operating. For example, this population may be unaware of a wildfire event or evacuation order which may prohibit them from evacuating in a timely manner.

Senior (65 years old and over) and Seniors Living Alone: The elderly population (i.e., seniors), especially those with access and functional needs, may have physical limitations that make it harder to evacuate in the event of an emergency due to a wildfire. Furthermore, the elderly population may lack access to social connections and community support that can assist in preparing for and responding to emergency events, evacuating, improving home resiliency, managing medical needs, and locating support services. These individuals are especially vulnerable to the health effects associated with wildfire smoke. A high concentration of the elderly population lives in central Contra Costa County, Bethel Island, eastern part of Richmond, and several parts of Walnut Creek. Seniors living alone may have caretakers, but for the most part

5.6.b
Packet Pg. 326 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 254 are living alone. This population is generally more vulnerable compared to other seniors because this group may have mobility issues that prohibit them from evacuating. In 2022, there were approximately 33,102 (8.0%) seniors living alone.310
Children, elderly, individuals with chronic illnesses, outdoor workers, and those experiencing homelessness are at a higher risk of the health effects attributed to wildfire smoke exposure. Short term exposure (i.e., over a few days) can cause irritation to the eyes and respiratory tract, respiratory symptoms (e.g., coughing, phlegm, wheezing, difficulty breathing), respiratory effects (e.g., bronchitis, reduced lung function, increased risk of asthma exacerbation and aggravation of other lung diseases, increased risk of emergency room visits and hospital admissions), cardiovascular effects (e.g., heart failure, heart attack, stroke, increased risk of emergency room visits and hospital admissions), and increased risk of premature death. Cumulative short-term exposure (i.e., over multiple days to a few weeks) can reduce lung function; and studies have not evaluated the health effects attributed to wildfire smoke exposure over multiple wildfire season (i.e., long-term exposure).311 Table 4-202 outlines the vulnerability of the total population exposed to wildfires, and Table 4-203 outlines the wildfire impacts to population and life safety, underserved/equity population, and essential operations, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Property Damage and Critical Infrastructure: Within the SRA and Very High FHSZ, there are existing homes, businesses, and public land uses, as well as associated infrastructure like major roadways (e.g., State Road 24 and State Road 4), electrical transmission lines, water and wastewater distribution systems, and communication facilities. Most of this development occurred prior to recent wildfire hazard mapping.

In Contra Costa County, there are electrical transmissions and distribution lines that are located in the mountainous areas which are located within the high fire hazards severity zones. Electrical transmission and distribution lines are power lines that carry high-voltage electricity long distances between power plants and electricity customers. This infrastructure can be damaged or destroyed by wildfires and cause residents and businesses within the County to lose power if electricity lines fail.

State Road 4 and 24, and Interstate 80 go through areas in the County that are within the moderate and very high fire hazard zones. In the event of a wildfire within this areas, can cause damage to roadways and road closures which can result in disruptions to commute and traffic patterns in the region.

Furthermore, closures on Highways 4 and 24 may prevent those in eastern and central Contra Costa County from traveling to the west. Single access roads, primarily located in hillside communities that are also within high or very high fire hazard severity zones, can be damaged or blocked due to wildfires.

There are 24 industrial buildings in the County that are within the fire hazard zone. Holding tanks and manufacturing centers that contain hazardous materials can be damaged by wildfires and release toxic materials into the air, water, and soil of the surrounding communities. 312 310 United States Census Bureau. (2022). DP02: Selected Social Characteristics in the United States (2022: ACS 1-Year Estimates Data Profiles). Retrieved from
https://data.census.gov/table/ACSDP1Y2022.DP02?g=050XX00US06013. 311 United States Environmental Protection Agency. (n.d.). Wildfire Smoke and Your Patients' Health. Retrieved from https://www.epa.gov/wildfire-smoke-course/health-effects-attributed-wildfire-smoke. 312 Ibid.

5.6.b
Packet Pg. 327 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 255 There are a total of 554 critical assets (i.e., schools, nursing homes, fire stations, police stations, and hospitals) throughout the County; seven (7) (1.3%) are located within the medium FHSZ, 12 (2.2%) are located within the high FHSZ, and 16 (2.9%) are located within the very high FHSZ. Table 4-197 provides a breakdown of critical assets that are located within the FHSZ in Contra Costa County.

Table 4-197. Critical Assets in Vulnerable to Wildfire
Asset Estimate Percent
(of total asset)
Medium Fire Hazard Severity Zone
Schools (public schools, private schools) 7 1.9%
Nursing Homes 0 0.0%
Fire Stations 0 0.0%
Police Stations 0 0.0%
Hospitals 0 0.0%
High Fire Hazard Severity Zone
Schools (public schools, private schools) 4 1.1%
Nursing Homes 0 0.0%
Fire Stations 8 9.9%
Police Stations 0 0.0%
Hospitals 0 0.0%
Very High Fire Hazard Severity Zone
Schools (public schools, private schools) 12 3.3%
Nursing Homes 0 0.0%
Fire Stations 4 4.9%
Police Stations 0 0.0%
Hospitals 0 0.0%
Table 4-202 outlines the total property value exposed to wildfires and how the changes in development in the past five (5) years have affected the vulnerability of the community to wildfires. Table 4-203 outlines the wildfire impacts on total property damage, potential future development, and the economy, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Environment: Fire is a natural and critical ecosystem process in most terrestrial ecosystems, dictating in part the types, structure, and spatial extent of native vegetation. However, wildfires can cause severe environmental impacts. In Contra Costa County, the following ecosystems and natural resources are vulnerable to wildfires:
313
313 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.

5.6.b
Packet Pg. 328 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 256 Agriculture: Crops, farms, and agriculture fields can be damaged by the smoke and ash from wildfires within and outside of Contra Costa County. Therefore, even though many agricultural lands are not within fire hazard zones, they can still be impacted by wildfires. Smoke and ash can change crops (e.g., wine grapes) and change nutrients in the soil which can cause plants to die or not produce as many usable fruits. This can cause significant economic hardship for farmers.

Regional Parks: Many regional parks within the County are located within high or very high fire hazard severity zones. Wildfire can destroy park facilities, damage trails and walking paths, and damage scenic views and vistas within the parks. This can impact the County economy because it may reduce the number of visitors to the parks.

Riparian Woodland and Shrub: Riparian woodland and shrub ecosystems consist of Valley foothill riparian, undetermined shrub, and riverine habitat. These areas are scattered throughout Contra Costa County and have numerous wildlife species (e.g., gray fox, striped skunk, broadhanded mole, mule deer, dusky-footed woodrat, yellow warbler, northern flicker, white tailed kite, and Cooper’s hawk). Wildfire can damage these ecosystems due to loss of canopy and changes in soil structure, erosion, and shifts in the specific composition due to change in the structure of the habitat.

Woodland: Woodland ecosystems include oak savannah, oak woodland, and mixed evergreen forest. These ecosystems are primarily located on the hillsides and mountainous regions of western and central Contra Costa County and have numerous wildlife species (e.g., deer mouse, western gray squirrel, coyote, red-tailed hawk, barn owl, great horned owl, and acorn woodpecker). Fire sensitivity varies by species; however, most species have an elevated vulnerability to wildfires. Widespread devastation can be caused by wildfires through the woodland areas particularly if trees have been weakened or killed by drought, extreme heat, and/or pests or infestation.

Table 4-203 outlines the wildfire impacts on the environment and economy, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Changes in Development and Impact of Future Development: Changes in development, since completion of the previous Plan, have not had a significant impact on the County wildfire hazards.

However, fire activity is projected to increase where development expands in the WUI areas, in addition to the dry hills around Mount Diablo. Nonetheless, Contra Costa County intends to protect against and adapt to the increases in frequency and intensity of wildfire events through a series of implementation actions outlined in in the Couty’s Climate Action Plan. This strategy aims to increase community resilience to the direct and indirect effects of wildfires. Public and private property shall be designed and maintained to minimize the risk of damage from wildfires; infrastructure systems will be hardened and designed to include redundancy; and emergency management plans and practices for wildfires will be responsive to the needs of underserved communities. Strategies such as this should help reduce the impacts of future development within wildfire hazards areas.

Table 4-202 outlines how the changes in development in the past five (5) years have affected the vulnerability of the community to wildfires. Table 4-203 outlines the wildfire impacts on potential future development, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

Effects of Climate Change in Severity of Impacts: Changes in climate are creating warmer and drier conditions which are leading to longer and more active wildfire seasons. Studies have shown that the number of large wildfires has more than doubled in the western United States. Furthermore, projections show that a one (1) degree Fahrenheit increase in the average annual temperature could increase the

5.6.b
Packet Pg. 329 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 257 average burned area per year by as much as 600% (in some types of forests) in the western United States. 314
In California, wildfires are expected to increase in frequency and severity due to climate change. As temperatures continue to rise, an increase in drought conditions, and forestry pests and diseases are likely to create more fuel in State and federal wildlands and a greater chance that a small fire can develop into a more dangerous wildfire. Excessive heat and dry conditions have already contributed to the rapid spread of wildfires during past events in Contra Costa County. Additionally, climate change is also expected to extend the fire season throughout much (or even all) of the year.315 Table 4-198 indicates the 25-year heat and precipitation projections for Contra Costa County.316 Table 4-199 outlines the wildfire associated climate indicators for Contra Costa County projected through the end of the century.317
Table 4-198. 25-Year Climate Projections for Contra Costa County Higher Emissions (RCP8.5)
Contra Costa County is expected to experience a 47% increase in extremely hot days and a 5% increase in days with heavy precipitation within 25 years.

By 2049, Contra Costa County is expected to experience 11 more days that reach above 95°F (from six (6) days to 11 days per year).

By 2049, Contra Costa County is expected to have a 2°F increase (from 61°F to 63°F) in average annual temperatures.

By 2049, Contra Costa County is expected to experience 0.1 more days of heavy precipitation per year (from

2.8 days to 2.9 days per year).

By 2049, Contra Costa County is expected to have a 0.3 inch increase (from 19.6 19.9 precipitation.

Lower Emissions (RCP4.5)
Contra Costa County is expected to experience a 32% increase in extremely hot days and a 13% increase in days with heavy precipitation within 25 years.

By 2049, Contra Costa County is expected to experience seven (7) more days that reach above 95°F (from 22 days to 29 days per year).

By 2049, Contra Costa County is expected to have a 1°F increase (from 61°F to 62°F) in average annual temperatures.

By 2049, Contra Costa County is expected to experience 0.3 more days of heavy precipitation per year (from

2.5 days to 2.8 days per year).

By 2049, Contra Costa County is expected to have a 0.4 inch increase (from 19 19.5 precipitation.
314 NOAA. (2023). Wildfire Climate Connection. Retrieved from https://www.noaa.gov/noaa-wildfire/wildfireclimate-connection. 315 Contra Costa County. (2023). Climate Action Plan (Public Review Draft). Retrieved from https://envisioncontracosta2040.org/wp-content/uploads/2023/10/CoCoCounty-2024CAP-PublicDRAFT-10-10- 23_Final.pdf.
316 Northeast Regional Climate Center. (n.d.). Neighborhoods at Risk: Climate Projections. Retrieved from https://nar.headwaterseconomics.org/.
317 Climate Mapping for Resilience and Adaptation. (n.d.). Climate Mapping for Resilience and Adaptation Assessment Tool. Retrieved from https://livingatlas.arcgis.com/assessment-tool/explore/details.

5.6.b
Packet Pg. 330 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 258 Table 4-199. Future Climate Indicators for Contra Costa County Indicators
Modeled
History
(1976 – 2005)
Early Century
(2015 – 2044)
Mid Century
(2035 – 2064)
Late Century
(2070 – 2099)
Lower
Emissions
Higher
Emissions
Lower
Emissions
Higher
Emissions
Lower
Emissions
Higher
Emissions
Min – Max Min – Max Min – Max Min – Max Min – Max Min – Max Min – Max Precipitation
Days per year with no
precipitation
(Dry Days)
281 days 286 days 283 days 285 days 285 days 285 days 288 days 277 – 285 275 – 291 274 – 291 275 – 298 267 – 296 275 – 296 271 – 307 Maximum number of
consecutive dry days
95 days 97 days 98 days 97 days 99 days 98 days 102 days 85 – 113 84 – 113 88 – 110 83 – 118 82 – 117 80 – 121 76 – 139 Days per year with
precipitation
(Wet Days)
84 days 82 days 82 days 80 days 80 days 80 days 77 days 80 – 88 74 – 91 74 – 91 68 – 91 69 – 98 70 – 90 58 – 94 Temperature Thresholds
Annual days with
maximum temperature
greater than 90°F
36 days 55 days 57 days 62 days 68 days 70 days 90 days 36 – 43 47 – 63 51 – 65 51 – 74 55 – 84 57 – 91 72 – 124 Annual days with
maximum temperature
greater than 100°F
5 days 10 day 11 days 13 days 16 days 17 days 29 days
4 – 6 7 – 14 8 – 16 9 – 22 9 – 28 10 – 22 19 – 57
Table 4-203 outlines the climate change impacts to wildfires in Contra Costa County, as outlined in the risk assessment methodology in Section 4.3 of this Plan.

5.6.b
Packet Pg. 331 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Wildfire Medium Significant hazard event is likely to occur within 25 years. 2 N/A Wildfire
Extent/Intensity High Historical and/or probabilistic models/studies for this hazard indicate the possibility of a high-intensity incident. 3 9Catastrophic High Catastrophic hazard event is likely to occur at least once in 10 years. 3 9 Wildfire
Population Exposure Medium 15% to 29% of the population is exposed to the hazard. 2 6Property Exposure Medium 10% to 24% of the total assessed property value is exposed to a hazard. 2 4Changes inDevelopment Medium Changes in development have increased thevulnerability/exposure of the community to the hazardbetween 5% and 9%. 2 2 Sea Level Rise
Population and LifeSafety Medium
Populations exposed to this hazard are likely to experiencesome adverse impacts, such as injuries requiring acutemedical care. 2 6 Underserved/Equity Medium
Underserved populations exposed to the hazard are likely toexperience some adverse/disproportionate impacts, such asinjuries requiring acute medical care. 2 6 Property Damage High
More than $5 Million in property damages is expected from asingle major hazard event, or damages are expected to occurto 15% or more of the property value within the jurisdiction. 3 6 Economic Medium Total economic impact is likely to be greater than $500,000, but less than or equal to $10 Million. 2 2

5.6.b
Packet Pg. 332 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Environmental High
Environmental impact from a single major hazard event islikely to be significant, requiring extensive outside resourcesand support; and/or repair, clean-up, restoration, and/orpreservation work. 3 3
Essential Operations Medium
Impact between 24 and 72 hours on the ability of thejurisdiction to meet the essential day-to-day operationaldemands and needs of the community from a single majorhazard event. 2 2
Future Development High Future development trends will significantly increase the impact/consequence of this hazard. 3 3Climate Change High Climate Change trends will significantly increase the risk of this hazard and its impacts. 3 3

5.6.b
Packet Pg. 333 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 261

4.6.10.8. FEMA NRI Expected Annual Loss Estimates
A wildfire NRI EAL score, and rating represent a community's relative level of expected building, population, and agriculture loss each year due to wildfires when compared to the rest of the United States.

The EAL score is positively associated to a community’s risk; therefore, a higher EAL score results in a higher Risk Index score. Table 4-204 outlines the wildfire EAL for Contra Costa County.

Table 4-204. Wildfire Expected Annual Loss (FEMA National Risk Index) Jurisdiction Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual
Loss
Expected
Annual
Loss
Score
Rating
Contra Costa
County $161,110 $5.7 Million $0 $5.8 Million 96.7 Very High Expected annual loss scores are calculated utilizing an equation that combines values for exposure, annualized frequency, and historic loss ratios (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio).

4.6.10.9. FEMA Wildfire Risk Index Scores
The wildfire Risk Index score and rating represent a community's relative risk for wildfires when compared to the rest of the United States. Table 4-205 illustrates the wildfire Risk Index rating and score for Contra Costa County.

Table 4-205. Wildfire Risk Index (FEMA National Risk Index) Jurisdiction Rating Score
Contra Costa County Very High 95.9
Risk Index scores are calculated using an equation that combines scores for Expected Annual Loss due to natural hazards, Social Vulnerability and Community Resilience (Expected Annual Loss x Social Vulnerability / Community Resilience = Risk Index).

5.6.b
Packet Pg. 334 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 262 Table 4-206 represents the Wildfire Total Risk Score for Contra Costa County, based on the Risk Assessment Methodology, as defined in this Plan. For further details on how the probability, extent, vulnerability, and impact factors were calculated, please refer to Table 4-200 through Table 4-203.

Additional details on how the Total Risk Score was calculated can be found in the Risk Assessment Methodology in Section 4.3 of this Plan.

Table 4-206. Wildfire Total Risk Score
Hazard
Event
Probability Consequence Total Risk
Probability
Factor Extent Vulnerability Impact ConsequenceScore
Total Risk
Score*
Wildfire 2 18 12 31 61 59
Consequence: Sum of all weighted factors.

Extent: Sum of the weighted Extent factors.

Vulnerability: Sum of the weighted Vulnerability factors.

Impact: Sum of the weighted Impact factors.

The Total Risk Score is a measure of Probability and Consequence.

5.6.b
Packet Pg. 335 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 263

4.6.11. Other Hazard of Concern
FEMA only requires and reviews natural hazards in hazard mitigation plans. However, Contra Costa County decided to include human-caused and technological hazards in this Hazard Mitigation Plan for the following reasons:

Contra Costa County takes a proactive approach to disaster preparedness in order to protect the public safety of all citizens.

Preparation for and response to a human-caused disaster involves much of the same staff training, critical decision making, and commitment of resources as a natural hazard.

The multi-hazard mitigation planning effort is an opportunity to inform the public about all hazards, including human-caused and technological hazards.

The likelihood of a human-caused and technological hazard event in the planning area is greater than that of several of the natural hazards identified in this Plan.

Due to the nature of non-natural hazards and the discretionary status regarding their inclusion, the following hazards of interest have been briefly and qualitatively assessed for the sake of public education and informing their inclusion within the hazard ranking and mitigation process.

5.6.b
Packet Pg. 336 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 264

4.6.11.1. Cybersecurity Threats
Description
A cybersecurity threat is an act or threat that poses potentially devastating disruptions to the digital infrastructure of a person or organization, often for financial or terror-related reasons. Generally, attacks last minutes to days, but large-scale events and their impacts can last much longer. As information technology continues to grow in capability and interconnectivity, cyber threats become increasingly frequent and destructive.

Cyber threats differ by motive, attack type and perpetrator profile. Motives range from the pursuit of financial gain to political or social aims. Cyber threats are difficult to identify and comprehend. Types of threats include using viruses to erase entire systems, breaking into systems, and altering files, using someone’s personal computer to attack others, or stealing confidential information. The spectrum of cyber risks is limitless, with threats having a wide range of effects on the individual, community, organizational, and national threat.

Cyberattacks and cyberterrorism are terms for cyber security threats that often are used interchangeably, though they are not the same. All cyberterrorism is a form of cyberattack, but not all cyberattacks are cyberterrorism.

Cyber Attacks
A cyber attack is an attempt by cybercriminals, hackers, or other digital adversaries to access a computer network or system, usually for the purpose of altering, stealing, destroying, or exposing information.

Public and private computer systems can experience a variety of cyberattacks, from blanket malware infection to targeted attacks on system capabilities. Cyberattacks specifically seek to breach information technology security measures designed to protect an individual or organization. The initial attack is followed by more severe attacks for the purpose of causing harm, stealing data, or financial gain.

Organizations are prone to different types of attacks that can be automated or targeted. Table 4-207 describes the 10 most common types of cyberattack. 318
Table 4-207. Common Types of Cyberattacks
Type Description
Malware
Also known as a malicious software, is any program or code that is created with the intent to do harm to a computer, network, or server. Malware is the most common type of cyberattack, mostly because this term encompasses many subsets such as ransomware, trojans, spyware, viruses, worms, keyloggers, bots, cryptojacking, and any other type of malware attack that leverages software in a malicious way.

Denial of Service
Attacks
A malicious, targeted attack that floods a network with false requests in order to disrupt business operations. Users are unable to perform routine and necessary tasks (e.g., accessing e-mail, websites, online accounts or other resources that are operated by a compromised computer or network). While most of these attacks do not result in lost data and are typically resolved without paying a ransom, they cost the organization time, money, and other resources in order to restore critical business operations.

Phishing
Uses e-mail, SMS, phone, social media, and social engineering techniques to entice a victim to share sensitive information (e.g., passwords, account numbers) or to download a malicious file that will install viruses on their computer or phone. 318 Baker, K. (2023). 10 Most Common Types of Cyber Attacks. Retrieved from https://www.crowdstrike.com/cybersecurity-101/cyberattacks/most-common-types-of-cyberattacks/.

5.6.b
Packet Pg. 337 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 265 Type Description
Spoofing
A technique where a cybercriminal disguises themselves as a known or trusted source.

The adversary is able to engage with the target and access their systems or devices with the ultimate goal of stealing information, extorting money, or installing malware or other harmful software on the device.

Identity Based
Attacks
These are hard to detect. When a valid user’s credentials have been compromised and an adversary is masquerading as that user, it is often very difficult to differentiate between the user’s typical behavior and that of the hacker using traditional security measures and tools.

Code Injection
Attacks
The attacks consist of an attacker injecting malicious code into a vulnerable computer or network to change its course of action.

Supply Chain Attacks Targets a trusted third-party vendor who offers services or software vital to the supply chain.

Insider Threats
Internal actors such as current or former employees that pose danger to an organization because they have direct access to the company network, sensitive data, and intellectual property (IP), as well as knowledge of business processes, company policies or other information that would help carry out such an attack.

Domain Name
System Tunneling
Leverages domain name system (DNS) queries and responses to bypass traditional security measures and transmit data and code within the network; and once infected, the hacker can freely engage in command-and-control activities.

Internet of Things
Based Attacks
Targets an Internet of Things (IoT) device or network; and once compromised, the hacker can assume control of the device, steal data, or join a group of infected devices to create a botnet to launch DoS or DDoS attacks.

Cyberterrorism
Cyberterrorism is the use of computers and information, particularly over the Internet, to recruit others to an organization’s cause, cause physical or financial harm, or cause a severe disruption of infrastructure service. Such disruptions can be driven by religious, political, or other motives. Like traditional terrorism tactics, cyberterrorism seeks to evoke very strong emotional reactions, but it does so through information technology rather than a physically violent or disruptive action. Cyberterrorism has three (3) main types of objectives, listed in Table 4-208.

Table 4-208. Counterterrorism Objectives
Type Description
Organizational
Includes specific functions outside of or in addition to a typical cyberattack. Terrorist groups today use the internet on a daily basis. This daily use may include recruitment, training, fundraising, communication, or planning. Organizational cyberterrorism can use platforms such as social media as a tool to spread a message beyond country borders and instigate physical forms of terrorism. Additionally, systematic attacks may be used as tools for training new members in cyberterrorism.

Undermining
Seeks to hinder the normal functioning of computer systems, services, or websites.

Such methods include defacing, denying, and exposing information. While undermining tactics are typically used due to high dependence on online structures to support vital operational functions, they typically do not result in grave consequences unless undertaken as part of a larger attack. Undermining attacks on computers include the following:

Directing conventional kinetic weapons against computer equipment, a computer facility, or transmission lines to create a physical attack that disrupts the reliability of equipment.

Using electromagnetic energy, most commonly in the form of an electromagnetic pulse, against computer equipment or data transmissions. By

5.6.b
Packet Pg. 338 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 266 Type Description
overheating circuitry or jamming communications, an electronic attack disrupts the reliability of equipment and the integrity of data.

Directing malicious code against computer processing code, instruction logic, or data. The malicious code can generate a stream of network packets that disrupt data or logic by exploiting vulnerability in computer software, or a weakness in computer security practices. This type of cyberattack can disrupt the reliability of equipment, the integrity of data, and the confidentiality of communications
Destructive
The destructive objective for cyberterrorism is what organizations fear most. Through the use of computer technology and the Internet, the terrorists seek to inflict destruction or damage on tangible property or assets, and even death or injury to individuals. There are no cases of pure destructive cyberterrorism as of the date of this plan.

Hazard Location
This hazard is not geography-based. Attacks can originate from any computer to affect any other computer in the world. If a system is connected to the Internet or operating on a wireless frequency, it is susceptible to exploitation. Targets of cyber attacks can be individual computers, networks, organizations, business sectors, or governments. Financial institutions and retailers are often targeted to extract personal and financial data that can be used to steal money from individuals and banks. The most affected sectors are finance, energy and utilities, and defense and aerospace, as well as communication, retail, and health care. Both public and private operations in Contra Costa County are threatened on a near-daily basis by millions of current cyberattacks developed to automatically seek technological vulnerabilities.

Hazard Extent/Intensity
An international study released by Malwarebytes in 2016 found that cyber ransom threats caused 34% of business victims to lose revenue and 20% had to stop business immediately. The study also reported that nearly 60% of all cyber ransom attacks demanded over $1,000, over 20% asked for more than $10,000, and 1% asked for over $150,000.

Warning Time
There is no warning time for cyber security threats. The top vector for spreading cyber ransom threats is e-mail.

Probability and Frequency
Cybersecurity threats are experienced on a daily basis, often without being noticed. Up-to-date virus protection software used in public and private sectors prevents most cyber-attacks from becoming successful. Programs that promote public education on virus protection are an effective way to mitigate cyber-threats. Cyberterrorism is much less common than cyber-attacks, though the frequency is unknown.

Past Events
Cybersecurity threats have not been publicly reported against local government agencies, schools, hospitals, or businesses in Contra Costa County.

California law requires a business to notify any California resident whose unencrypted personal information was acquired or is reasonably believed to have been acquired by an unauthorized person (California Civil Code Sections 1798.29(a) and1798.82(a)). The law also requires that a copy of any

5.6.b
Packet Pg. 339 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 267 breach notice sent to more than 500 California residents be provided to the California Attorney General.

The California Attorney General sent out notices notifying individuals of nearly 2,900 data breaches between 2012 and July 2022. 319
Vulnerability and Impacts
Life Safety: All populations who directly use a computer or receive services from automated systems are vulnerable to cybersecurity threats. Certain types of attacks would impact specific segments of the population. If the cybersecurity threat targeted the Pacific Gas and Electric Company (PG&E) power or utility grid, individuals with medical needs would be impacted the most. These populations are most vulnerable because many of the life-saving systems they rely on require power. If an attack occurred during extreme hot weather, individuals 65 years old and above would be vulnerable to the effects of the lack of air conditioning. These individuals might require an air conditioned shelter operating on a backup generator. If a cyber attack targeted a facility storing or manufacturing hazardous materials, individuals living adjacent to these facilities would be vulnerable.

Property: Cyber threats can cause physical damage if real assets or end consumers are affected by service disruption. This might occur if cyber threats target industries related to utilities, life support, transportation, human services, or telecommunications. In many cases, attacks on these systems initially will not be detected, and any malfunction will be thought to be system failure. Cybersecurity incidents can result in the theft or modification of important data – including personal, agency, or corporate information – and the sabotage of critical processes, including the provision of basic services by government or private-sector entities.

Critical Facilities and Infrastructure: A catastrophic cybersecurity threat can have far-ranging effects on public and private infrastructure systems. All critical facilities and infrastructure that are operated by electricity and/or a computer system are vulnerable to the cybersecurity threat. Cyber threats may affect structures if any critical electronic systems suffer service disruption. For instance, a cyber attack may cripple the electronic system that controls a cooling system or pressure system, resulting in physical damage to the structure from components overheating, or an explosion if pressure relief systems are rendered inoperable.

Economic: Cyber threats can have extensive fiscal impacts. Companies and government services can lose large sums of unrecoverable revenue from site downtime and compromise of sensitive confidential data. The economic impact of data and telecommunications losses can be high as computer security breaches, crime conducted via the internet such as identify theft, and many other forms of cyber attack occur daily. Millions of dollars are lost each year as criminals and cyberterrorists steal sensitive information and funds from individuals and organizations. 319 California Governor’s Office of Emergency Services. (2023). California State Hazard Mitigation Plan. Retrieved from https://www.caloes.ca.gov/wp-content/uploads/Hazard-Mitigation/Documents/2023-CaliforniaSHMP_Volume-1_11.10.2023.pdf.

5.6.b
Packet Pg. 340 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 268 Cybersecurity Threat Total Risk Score
Table 4-209 represents the cybersecurity threat Total Risk Score for the Contra Costa County, based on the Risk Assessment Methodology, as defined in this Plan.

Table 4-209. Cybersecurity Total Risk Score
Hazard
Event
Probability Consequence Total Risk
Probability
Factor Extent Vulnerability Impact ConsequenceScore
Total Risk
Score*
Cybersecurity Threat 2 12 7 13 32 34
Consequence: Sum of all weighted factors.

Extent: Sum of the weighted Extent factors.

Vulnerability: Sum of the weighted Vulnerability factors.

Impact: Sum of the weighted Impact factors.

The Total Risk Score is a measure of Probability and Consequence.

5.6.b
Packet Pg. 341 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 269

4.6.11.2. Hazardous Materials Incidents
Description
Hazardous materials are present in nearly every city and county in the United States in facilities that produce, store, or use them. For example, water treatment plants use chlorine on-site to eliminate bacterial contaminants. Hazardous materials are transported along interstate highways and railways daily. Even the natural gas used in every home and business is a dangerous substance when a leak occurs. Many businesses, through intentional action, lack of awareness or accidental occurrences, have contamination in and around their property.

Title 49 of the CFR lists thousands of hazardous materials, including gasoline, insecticides, household cleaning products, and radioactive materials. State-regulated substances that have the greatest probability of adversely impacting the community are listed in the CCR, Title 19.

The most common types of hazardous material incidents are listed in Table 4-210.

Table 4-210. Hazardous Materials Incident Types
Incident Type Description
Fixed-Facility
This is the uncontrolled release of materials from a fixed site capable of posing a risk to health, safety, and property. It is possible to identify and prepare for a fixed-site incident because laws require facilities to notify state and local authorities about what is being used or produced at the site.

Transportation
A hazardous materials transportation incident is any event resulting in uncontrolled release of materials during transport that can pose a risk to health, safety, and property. Transportation incidents are difficult to prepare for because there is little if any notice about what materials could be involved should an accident happen.

Hazardous materials transportation incidents can occur anywhere, although most occur on interstate highways or major federal or state highways, or on the major rail lines. In addition to materials such as chlorine that are shipped throughout the country by rail, thousands of shipments of radiological materials, mostly medical materials, and low-level radioactive waste, take place via ground transportation across the United States. Many incidents occur in sparsely populated areas and affect very few people.

Interstate Pipeline
A significant number of interstate natural gas, heating oil, and petroleum pipelines run through California. These are used to provide natural gas to utilities in California and to transport these materials from production facilities to end-users.

Business practices and the laws that regulate them have changed dramatically over the years. Hazardous materials management is regulated by federal and state codes. The state fire marshal and the Pipeline and Hazardous Materials Safety Administration enforce oil and gas pipeline safety regulations. The federal government enforces hazardous material transport pursuant to its interstate commerce regulation authority.

The Department of Toxic Substances Control (DTSC), a Division of the California Environmental Protection Agency, acts to protect California from exposure to hazardous wastes by cleaning up existing contamination and looking for ways to reduce the hazardous waste produced in the state. The DTSC regulates hazardous waste in California primarily under the authority of the federal Resource Conservation and Recovery Act, and the California Health and Safety Code. Other laws that affect hazardous waste are specific to handling, storage, transportation, disposal, treatment, reduction, cleanup, and emergency planning.

5.6.b
Packet Pg. 342 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 270 DTSC reviews and monitors legislation to ensure that proposed regulations reflect DTSC goals. DTSC’s major program areas develop regulations and consistent policies and procedures. Under the Resource Conservation and Recovery Act, DTSC has the authority to implement permitting, inspection, compliance and corrective action programs to ensure that people who manage hazardous waste follow state and federal requirements. As such, the management of hazardous sites in the planning area is under regulation by the DTSC, to ensure that state and federal regulations pertaining to hazardous waste are followed.

Businesses are required to disclose all hazardous materials and waste above certain designated quantities that they use, store, or handle at their facility. They must prepare chemical inventory and business emergency plans, review the plans regularly, and perform annual training. Any release or possible release of hazardous material must be reported to the Cal OES Warning Center. Businesses using certain regulated substances (a list of about 260 specific flammable or toxic chemicals) must develop a risk management plan. The risk management plan includes analysis of operations on-site, and projection of off-site consequences with accompanying mitigation plans.

Hazard Location
The following locations have the potential of hazardous materials releases:

Business and Industrial Areas: Retail, manufacturing and light industrial firms are areas of concern. These facilities have the highest concentration of hazardous materials at fixed facilities in the planning area due to their manufacturing operations. Each business is required to file a detailed plan with the Contra Costa Health Services Hazardous Materials Program regarding materials on-site and safety measures taken to protect the public.

Agricultural Areas: Accidental releases of pesticides, fertilizers, and other agricultural chemicals may be harmful to both humans and the environment. Agricultural pesticides are transported daily in and around the planning area en route to destinations in rural areas.

Illegal Drug Operations: Illegal operations such as laboratories for methamphetamine can pose a threat. Laboratory residues are often dumped along roadways or left in rented hotel rooms, creating a serious health threat to unsuspecting individuals and to the environment.

Illegal Dumping Sites: Hazardous wastes such as used motor oil, solvents, or paint are occasionally dumped in remote areas or along roadways, creating a potential health threat to unsuspecting individuals and to the environment.

Transportation Routes: The County’s transportation system consists of a network of federal, state, and county roads, airports, and rail service that all have the potential for hazardous material incidents:
o Interstates 80, 580, and 680, State Routes 4, 24, 123, and 242 o Amtrak long distance and intercity trains through the County o Railroad lines: Union Pacific owns 60 miles of lines, BNSF Railway has 55 miles of line, and two smaller lines (Sacramento Northern and Bay Point) operate in the County o General Aviation Airports: Buchanan Field, in the unincorporated county near Concord and Pleasant Hill; and Byron Airport near the Town of Byron.

Pipelines: Gas and hazardous liquid pipelines in Contra Costa County are vulnerable and possible sites for hazardous materials incidents.

5.6.b
Packet Pg. 343 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 271 Hazard Extent/Intensity
Hazardous materials come in the form of explosives, flammable and combustible substances, poisons and radioactive materials. Hazards can occur during production, storage, transportation, use or disposal.

The release or spill of hazardous materials requires a different response depending on factors such as the amount, type, and location of the spill. Each location should have its own specific cleanup procedure, and all personnel handling such material should have received instruction on that procedure. There has been no fatality in the County from hazardous material release since the Walnut Creek pipeline explosion in 2004. The last hazardous material release that had a fatality at a fixed facility was the MBA Polymers dust explosion in 2000.

Warning Time
Hazardous material incidents occur without predictability under circumstances that give responders little time to prepare. Contra Costa County uses the Community Warning System to disseminate information to the public in the event of a release or threatened release of a hazardous material. The system includes the integration of warning sirens, the local media, NOAA weather radios, computer terminals, emergency response personnel pages, and emergency phone notification through the telephone emergency notification system. The system also sends out text messages and provides information over Facebook and X (formerly Twitter). Contra Costa Health Services’ Hazardous Materials Incident Response Team provides general data to first responders to advise evacuations or sheltering in place.

Probability and Frequency
Hazardous material incidents may occur at any time in the planning area, given the presence of transportation routes dividing the planning area, the location of businesses and industry that use hazardous materials, the presence of scattered illegitimate businesses such as clandestine drug laboratories, and the improper disposal of hazardous waste.

Past Events
Table 4-211 lists the number of hazardous material incidents in Contra Costa County reported to the Cal OES Warning Center from 2018 through 2023.
320 Additional historical hazardous material spill report data is available on the Cal OES website. The records show 164 hazardous materials spills in Contra Costa County over the five (5) year timeframe.

Table 4-211. Hazardous Materials Incidents (Reported to CalOES) Spill Site 2018 2019 2020 2021 2022 2023 Total
Airport 0 0 0 0 0 0 0
Industrial Plant 0 1 0 1 0 0 2
Merchant/Business 4 2 6 2 4 1 19
Military Base 0 0 0 0 0 0 0
Oil Field 0 0 0 0 0 0 0
Other 3 0 1 1 1 2 8
Pipeline 0 0 0 0 0 0 0
Railroad 1 1 1 1 1 3 8
320 California Office of Emergency Services. (2023). Spill Release Reporting: Spill Report View. Retrieved from https://w3.calema.ca.gov/operational/malhaz.nsf/$defaultview.

5.6.b
Packet Pg. 344 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 272 Spill Site 2018 2019 2020 2021 2022 2023 Total
Refinery 8 15 1 2 4 3 33
Residence 7 4 2 4 3 1 21
Road 8 3 3 2 5 4 25
School 1 0 0 0 0 0 1
Service Station 2 1 0 0 1 2 6
Ship/Harbor/Port 1 0 2 1 1 0 5
Treatment/Sewage Facility 0 0 1 0 1 0 2
Utilities/Substation 0 0 0 1 0 0 1
Waterways 4 5 5 9 6 4 33
Total 39 32 22 24 27 20 164
Vulnerability and Impacts
Life Safety: People near facilities producing, storing, or transporting hazardous substances are at higher risk. Populations downstream, downwind, and downhill of a released substance are particularly vulnerable. A spill of a toxic airborne chemical in a populated area could have greater potential for loss of life. Depending on the characteristics of the substance released, more people in a larger area may be in danger from explosion, absorption, injection, ingestion, or inhalation. Often, people in the radius area (outside the immediate affected area) are evacuated as a precaution or told to shelter-in-place, depending on the release type and wind conditions.

Property: The impact of a fixed-facility hazardous materials incident will likely be localized to the property where it occurs. The impact of a spill of a small amount of a liquid chemical may be limited to remediation of soil.

Critical Facilities and Infrastructure: The impact of a hazardous material spill or transportation incident will likely be localized to the particular facility, hospital, port, airport, railroad, road, highway, or interstate.

The potential losses vary because of the variable nature of the hazardous material spill, but costs from product loss, property damage and decontamination and other costs can add up to millions of dollars.

Environment: Depending on the characteristic of the hazardous material or the volume of product involved, the affected area can be as small as a room in a building or as large as many square miles that require soil remediation. More widespread effects occur when a product contaminates the municipal water supply or water system such as a port, river, lake, or aquifer. Such environmental damage can linger for decades.

Economic: Large hazardous material spills can drive away tourists. Transportation incidents can temporarily shut down transportation routes. Studies that look at economic effects from bridge and highway losses consistently report job loss and economic losses in the billions of dollars. For example, 43% of businesses reporting losses after the 1994 Northridge Earthquake said they were due to transportation issues.

5.6.b
Packet Pg. 345 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 273 Hazardous Materials Incident Total Risk Score
Table 4-212 represents the hazardous materials incident Total Risk Score for the Contra Costa County, based on the Risk Assessment Methodology, as defined in this Plan.

Table 4-212. Hazardous Materials Incidents Total Risk Score Hazard
Event
Probability Consequence Total Risk
Probability
Factor Extent Vulnerability Impact ConsequenceScore
Total Risk
Score*
Hazardous Materials Incident 2 15 9 16 40 41
Consequence: Sum of all weighted factors.

Extent: Sum of the weighted Extent factors.

Vulnerability: Sum of the weighted Vulnerability factors.

Impact: Sum of the weighted Impact factors.

The Total Risk Score is a measure of Probability and Consequence.

5.6.b
Packet Pg. 346 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 274

4.6.11.3. Utility Interruptions
Description
Power Failure
A power failure is any interruption or loss of electrical service due to disruption of power generation or transmission caused by an accident, sabotage, natural hazards, equipment failure, or fuel shortage.

These interruptions can last anywhere from a few seconds to several days. Power failures are considered significant only if the local emergency management organization is required to coordinate basic services such as the provision of food, water, and heating as a result. Power failures are common with severe weather and winter storm activity.

PG&E is responsible for operating and maintaining the electrical transmission and distribution system in the planning area. Calpine Corporation energy centers in the Cities of Antioch and Pittsburg generate electricity from natural gas and geothermal resources and sell it to PG&E. Crockett Cogeneration operates a natural gas fired plant in Crockett, California and sells to PG&E. Refineries in the planning area have power generation plants that supply their operations. A co-generation facility next to the Tesoro refinery produces electricity for Tesoro and can sell it to PG&E.

Public Safety Power Shutoffs
A public safety power shutoff (PSPS) is an event in which a major electric power provider (e.g., PG&E) temporarily shuts off electrical power to a selected area to prevent power lines from sparking wildfires and threatening human lives. Utilities usually implement these during days with sustained winds or strong gusts, or other factors. The duration of a shutoff event is tied directly to the weather that triggers it; the shutoff typically ends within 24 hours after the weather conditions have subsided. However, PSPS events may extend beyond the 24-hour timeframe, depending on conditions.

PSPS events often target wildland areas with high wildfire risk, but they can impact a much wider region.

The targeted area is the area at risk due to weather conditions. Given the long, connected nature of power supply systems, a shutoff event targeted to a small at-risk zone can affect power to larger areas beyond. 321
Water or Wastewater Disruption
Water or wastewater disruption is a secondary impact from a natural disaster or intentional act. In the planning area, water service is provided by the City of Antioch, Contra Costa Water District, East Bay Municipal Utility District, Diablo Water District, Golden State Water Company and the Martinez Water District. Sewer services are provided by Central Contra Costa Sanitary District, Ironhouse Sanitary District, Delta Diablo Sanitation District, Mountain View Sanitary District, West County Wastewater District, Dublin San Ramon Services District, Rodeo Sanitary District, Pinole Sanitary District, Hercules Sanitary District, and Crockett Community Services District.

A breach in the pipelines that carry water through the planning area would have significant temporary impacts until alternative water sources are pumped and treated. Long-term disruption would have significant impacts on residences and businesses in the planning area if demand exceeds secondary supplies and water conservation measures do not provide enough relief to reduce demand to equal the secondary supplies.
321 California Governor’s Office of Emergency Services. (2023). California State Hazard Mitigation Plan. Retrieved from https://www.caloes.ca.gov/wp-content/uploads/Hazard-Mitigation/Documents/2023-CaliforniaSHMP_Volume-1_11.10.2023.pdf.

5.6.b
Packet Pg. 347 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 275 Disruption of the planning area’s wastewater collection and wastewater treatment plants would have significant regional impacts. Such disruption could result if the system were to be overwhelmed by a significant storm or discharge of materials in such quantities that the treatment plant could not adequately treat the waste. Natural hazards such as earthquakes or floods, major power outages, or terrorism directed at the facilities and systems could disrupt the process of collecting and treating millions of gallons of sewage. Wastewater treatment plants may also have emergencies internal to the plant such as oxygen deficiencies that render them incapable of treating waste. The disruption of service may also have significant environmental impacts on the waterways adjacent to the treatment plants.

Data and Telecommunications Interruptions
The loss of data or telecommunications is often a secondary hazard to natural and other human-caused hazards. Data and telecommunications provide a primary method for service to the community by the government and the private sector. A loss of data and telecommunications could result in loss of emergency dispatch capabilities, emergency planning services, infrastructure monitoring capabilities, access to statistical data, and access to financial and personnel records.

Pipeline Interruptions
Pipelines are often considered the safest and most reliable way to transport natural gas, crude oil, liquid petroleum products, and chemical products, but there is still an inherent risk due to the nature of the hazardous materials.

Failures of pipelines can occur when pipes corrode, are damaged during excavation, are incorrectly operated, or are damaged by other forces. One of the worst hazardous material incidents in the County involved a pipeline carrying gasoline in November 2004 in Walnut Creek. The released gasoline ignited, and five people were killed.

Intra-state liquid petroleum pipelines are regulated by the Office of the State Fire Marshal Pipeline Safety Division. Natural gas pipelines are regulated by the California Public Utilities Commission. Pipelines are also monitored by supervisory control and data acquisition systems that measure flow rate, temperature and pressure. These systems transfer real-time data via satellite from the pipelines to a control center where valves, pumps, and motors are remotely operated. If tampering with the pipeline occurs, an alarm sounds. The ensuing valve reaction is instantaneous, with the system isolating any rupture and setting off a chain reaction that shuts down pipeline pumps and alerts pipeline operators within seconds.

Transmission pipelines and distribution pipelines provide different services. Transmission pipelines transport raw material for further refinement. These pipes are large and far reaching, operating under high pressure. Distribution pipelines provide processed materials to end users. These are smaller in diameter, some as small as half an inch, and operate under lower pressure. More serious accidents occur on distribution pipelines than on any other type due to their number, intricate networking, and location in highly populated areas.

Hazard Location
Electrical generation, transmission, and distribution system are located throughout the planning area.

Hazard Extent/Intensity
The severity of utility failure and power interruptions varies too widely to be able to be measured.

Electricity, for example, may be out for a few hours to several weeks, depending on the cause of the event.

5.6.b
Packet Pg. 348 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 276 Warning Time
Utility failure and power interruptions occur at any time without warning. However, they usually are a secondary effect from a storm event, landslide, earthquake, and human-caused issues.

Probability and Frequency
The probability and frequency of utility failure and power interruption incidents is likely to remain constant, but the length of time a utility is shut down should lessen in the future as more redundancies are built into infrastructure and utilities. In addition, leak detection sensors alert utilities to faults and failures more quickly.

Past Events
Table 4-213 lists utility interruption incidents that have occurred in Contra Costa County between 2018 and 2023.

Table 4-213. Utility Interruption Past Events
Date Event Summary
08/17/2021 A PSPS was implemented by PG&E and it was concentrated along central Contra Costa County.
11/20/2019 A 24-hour PSPS was implemented by PG&E which resulted in 23,000 residents without power.
10/26/2019
Due to extreme heat, low humidity, and wind Countywide PSPSs were implemented by PG&E. At its height over 50,000 residents experienced long term utility interruptions.

There were significant wildfire impacts. Multiple PSPSs impacted the County. The County EOC was activated and proclaimed an emergency.
10/10/2019
Due to extreme heat, low humidity, and wind Countywide PSPS were implemented by PG&E. At its height over 50,000 residents experienced long term utility interruptions.

The County EOC was partially activated.

Vulnerability and Impacts
Life Safety: The entire planning area is vulnerable to utility interruptions.

Property: All property is exposed and vulnerable to some type of utility infrastructure failure throughout the planning area.

Critical Facilities and Infrastructure: Critical facilities are vulnerable to utility interruption. But the adverse effect of damaged critical facilities can extend beyond direct physical damage. It can disrupt health care, fire, and police services, impair search and rescue, and emergency medical care.

Environment: The environment is vulnerable to utility interruption if the utility has a spill that contaminates water and/or open land, or creates a wildfire that burns acres.

Economic: Utility losses could cause a reduction in employment and wholesale and retail sales, a need for utility repairs, and increased medical risks. Local governments might lose tax revenues, and the finances of private utility companies and the businesses that rely on them would be disrupted.

5.6.b
Packet Pg. 349 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 277 Utility Interruptions Total Risk Score
Table 4-214 represents the utility interruptions Total Risk Score for the Contra Costa County, based on the Risk Assessment Methodology, as defined in this Plan.

Table 4-214. Utility Interruptions Total Risk Score
Hazard
Event
Probability Consequence Total Risk
Probability
Factor Extent Vulnerability Impact ConsequenceScore
Total Risk
Score*
Utility Interruptions 3 9 7 18 34 51
Consequence: Sum of all weighted factors.

Extent: Sum of the weighted Extent factors.

Vulnerability: Sum of the weighted Vulnerability factors.

Impact: Sum of the weighted Impact factors.

The Total Risk Score is a measure of Probability and Consequence.

5.6.b
Packet Pg. 350 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 278

4.6.11.4. Active Shooter Incidents
Description
Active shooter incidents are typically motivated by the desire to maximize human casualties. They are differentiated from other attack types by the indiscriminate nature of the victim’s targets of opportunity rather than actions directed toward a specific target. The Federal Bureau of Investigation (FBI) defines an active shooter as one (1) or more individuals actively engaged in killing or attempting to kill people, with a firearm, in a populated area. 322 They may use small arms (e.g., revolvers, automatic pistols, rifles, shotguns, assault rifles, light machine guns), light weapons (e.g., medium caliber and explosive ordinance, grenade launchers, rocket propelled grenades), or both, depending on the type of attack. The following are characteristics that police and sheriff departments have often seen associated with active shooters.

Active shooters may focus on specific individuals, or they may be intent on killing as many randomly chosen people as possible.

Their purpose is usually an expression of hatred or rage, rather than financial gain or motives associated with other types of crimes. Thus, police tactics of containment and negotiation may be an inadequate response to an active shooter.

They chose a site that they are familiar with and have made detailed plans for the attack. In many cases, they are very well armed.

Active shooters often, but not always, are suicidal. Escaping the police is not usually a priority and in general, they have not attempted to hide their identity.

The location chosen for the incident usually has a tactical advantage.

Active shooter incidents are unpredictable and evolve quickly. Because active shooter incidents are often over within five (5) to 10 minutes, before law enforcement arrives on the scene, individuals at the scene must be prepared both mentally and physically to deal with the shooting in progress situation. In most cases, active shooters use firearms and there is no pattern or method to their selection of victims. 323 Hazard Location
According to recent studies, 77% of active shooter incidents occur in commercial, education, or government environments. Usually, the shooter is familiar with the chosen area and the area offers a tactical advantage.

Hazard Extent/Intensity
The severity of an active shooter incident may vary from a few injured people to multiple injuries and fatalities.

Warning Time
The only warning of an active shooter incident is if a citizen notices unusual happenings and reports them before the shooting starts. The incident itself may be over in 5 to 10 minutes. 322 Federal Bureau of Investigation. (2023). Active Shooter Incidents in the United States in 2022. Retrieved from https://www.fbi.gov/file-repository/active-shooter-incidents-in-the-us-2022-042623.pdf/view. 323 Cybersecurity & Infrastructure Security Agency. (n.d). Active Shooter Preparedness. Retrieved from https://www.cisa.gov/topics/physical-security/active-shooter-preparedness.

5.6.b
Packet Pg. 351 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 279 Probability and Frequency
While the probability and frequency of active shooter incidents has been low in the planning area, these incidents can happen anywhere and at any time.

Past Events
On October 31, 2019, five (5) people were killed and four (4) were wounded when a shooter opened fire during a Halloween block party in the City of Orinda.
324 Based on the FBI annual active shooter reports,
between 2018 and 2022, a total of 23 active shooter incidents have occurred in in the State of California.
325, 326, 327, 328, 329 Between 2018 and 2023, the deadliest active shooter incident in California occurred in 2018 when the shooter opened fire at the Borderline Bar and Grill in Thousand Oaks killing

11. 330 While not located in Contra Costa County, this event highlights that active shooters can target any location where there is a gathering of individuals.

Vulnerability and Impacts
Life Safety: All individuals in the planning area are considered to be at risk of active shooter incidents.

Property: The intent of an active shooter is to harm persons; property may be incidentally damaged, but the shooter’s intent does not generally focus on property.

Critical Facilities and Infrastructure: Critical facilities are unlikely to experience significant damage from an active shooter incident.

Environment: The environment is unlikely to experience significant damage from an active shooter incident.

Economic: Economic impacts can occur from loss of patrons coming to a local business where an incident occurred, down time from a closed business, and loss of wages for an individual who was injured or killed.
324 Navarro, H. (2023). List: California Mass Shootings of the Past Decade. Retrieved from https://www.nbclosangeles.com/news/list-california-mass-shootings/3081419/. 325 Federal Bureau of Investigation. (2019). Active Shooter Incidents in the United States in 2018. Retrieved from https://www.fbi.gov/file-repository/active-shooter-incidents-in-the-us-2018-041019.pdf/view. 326 Federal Bureau of Investigation. (2020). Active Shooter Incidents in the United States in 2019. Retrieved from https://www.fbi.gov/file-repository/active-shooter-incidents-in-the-us-2019-042820.pdf/view. 327 Federal Bureau of Investigation. (2021). Active Shooter Incidents in the United States in 2020. Retrieved from https://www.fbi.gov/file-repository/active-shooter-incidents-in-the-us-2020-070121.pdf/view. 328 Federal Bureau of Investigation. (2022). Active Shooter Incidents in the United States in 2021. Retrieved from https://www.fbi.gov/file-repository/active-shooter-incidents-in-the-us-2021-052422.pdf/view. 329 Federal Bureau of Investigation. (2023). Active Shooter Incidents in the United States in 2022. Retrieved from https://www.fbi.gov/file-repository/active-shooter-incidents-in-the-us-2022-042623.pdf/view. 330 Kesslen, B. (2021). Gunman in 2018 Thousand Oaks Shooting Motivated by Hatred of College Students, Report Says. Retrieved from https://www.nbcnews.com/news/us-news/gunman-2018-thousand-oaks-shootingmotivated-hatred-college-students-report-n1272936.

5.6.b
Packet Pg. 352 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 280 Active Shooter Incident Total Risk Score
Table 4-215 represents the active shooter incident Total Risk Score for the Contra Costa County, based on the Risk Assessment Methodology, as defined in this Plan.

Table 4-215. Active Shooter Total Risk Score
Hazard
Event
Probability Consequence Total Risk
Probability
Factor Extent Vulnerability Impact ConsequenceScore
Total Risk
Score*
Active Shooter Incident 2 9 5 15 29 32
Consequence: Sum of all weighted factors.

Extent: Sum of the weighted Extent factors.

Vulnerability: Sum of the weighted Vulnerability factors.

Impact: Sum of the weighted Impact factors.

The Total Risk Score is a measure of Probability and Consequence.

5.6.b
Packet Pg. 353 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 281

4.6.11.5. Terrorism
Description
Terrorism can take many forms, but its overall goal is to cause as much disruption and fear as possible within the targeted population. The Federal Bureau of Investigation (FBI) defines terrorism as the unlawful use of force or violence against people or property to intimidate or coerce a government or civilian population in protest of political or social objectives. 331 Additionally, the FBI further defines international and domestic terrorism. International terrorism is a violent and criminal act committed by individuals and/or groups who are inspired by, or associated with, designated foreign terrorist organizations or nations (18 USC §2331 (1)). Domestic terrorism is a violent and criminal act committed by individuals and/or groups to further ideological goals stemming from domestic influences (e.g., political, religious, social, racial, or environmental) (18 USC §2331 (5)). 332 Typically, terrorism events involve mass casualty incidents and take place without warning. The most common methods of these incidents include mass shootings, explosive devices, and bladed instruments. 333 Cars, buses, trains, aircraft, and marine vessels have been used as conveyances and as weapons in terrorist acts. In recent years terrorists have utilized additional methods including kidnappings, biological weapons, and cyberattacks to inflict terror on the targeted population.

Cybersecurity and active shooter will be addressed separately in this Plan.

The goal of a terrorist attack is to cause maximum disruption and fear; therefore, an economically significant area is a logical and potential target. A terrorism event within the Contra Costa County area would cause significant economic disruption, along with potentially cascading effects.

California’s population, industrial infrastructure, economic importance, international reputation, media industry, and numerous iconic features combine to make the state a potential target for both domestic and international terrorist attacks. Terrorists typically exploit vulnerabilities caused by technological hazards and may include hazardous materials release; biological agents that result in epidemics; or attempts to damage the state’s critical infrastructure including cyberattacks, which pose potentially devastating disruptions to essential communications (e.g., voice, e-mail, and internet connectivity).

According to the United States Department of Homeland Security (DHS), the greatest number of domestic terrorism incidents between 2010 and 2022 occurred in states with major metropolitan areas such as California (Los Angeles, San Diego, and San Francisco). 334 Hazard Location
Contra Costa County has identified numerous high-profile targets for potential terrorist incidents. Large population centers, high visibility tourist attractions, and critical infrastructure accessible to the public present security challenges of an ongoing nature in the planning area.

Hazard Extent/Intensity
The severity of a terrorist attack may vary from a few injured people to multiple injuries and fatalities. 331 U.S Department of Justice Office of Justice and Programs. (1987). FBI and Terrorism. Retrieved from:
https://www.ojp.gov/ncjrs/virtual-library/abstracts/fbi-and-terrorism. 332 Federal Bureau of Investigation. (n.d.). Terrorism. Retrieved from https://www.fbi.gov/investigate/terrorism. 333 Counter Terrorism Ethics. (n.d.). Terrorist Group: Al Qaeda Weapons Use. Retrieved from https://counterterrorismethics.tudelft.nl/the-past-present-and-future-weapon-use-of-al-qaeda/. 334 U.S. Government Accountability Office. (2023). The Rising Threat of Domestic Terrorism in the U.S. and Federal Efforts to Combat It. Retrieved from https://www.gao.gov/blog/rising-threat-domestic-terrorism-u.s.-andfederal-efforts-combat-it.

5.6.b
Packet Pg. 354 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 282 Warning Time
According to experts, fewer than 5% of all terrorism incidents are preceded by a warning or threat.

Probability and Frequency
The probability of a terrorist event varies with the method of attack, as follows:

Chemical: The risk of a chemical event is present in the planning area. The petroleum and agricultural community uses and stores significant amounts of chemicals that could be used in destructive ways.

Explosives: The elements necessary to construct a Weapons of Mass Destruction (WMD) explosive are readily available. Agricultural communities maintain sufficient products for use in explosive devices. Pipe bomb and suspicious package events have occurred in Contra Costa County, though none have been specifically identified as a WMD.

Radiological/Nuclear: The major transportation arteries for vehicles or rail that cross through or near the planning area contribute to the risk of a radiological event. Such products can pass through any of the regional transportation corridors.

Biological: Anthrax incidents that occurred in the U.S. in October 2001 demonstrate the potential for spreading terror through biological weapons. An agent also could be introduced to livestock, causing harm to public health and the economy.

Combined Hazards: WMD agents can be combined to have a greater total effect. Given the risks associated with chemical agents in Contra Costa County, the possibility of a combined event exists.

Past Events
Terrorism incidents in Contra Costa County have been limited. The most recent was a pipe bomb found in December 2015 at a person’s home that threatened a Richmond mosque.

Vulnerability and Impacts
Life Safety: Although terrorism has not resulted in a large number of deaths in Contra Costa County, it can be deadly and widespread. Any individuals exposed to human-caused hazards are considered to be at risk, particularly those working as first responders.

Property: All structures in the planning area are physically vulnerable to a terrorism event. Factors that affect vulnerability include an emphasis on accessibility, opportunities for roof access, driveways underneath structures, unmonitored areas, and the proximity of structures to transportation corridors and underground pipelines.

Critical Facilities and Infrastructure: The U.S. Office of Homeland Security created the 2003 National Strategy for the Physical Protection of Critical Infrastructure of Critical Infrastructure and Key Assets, which lays a foundation to work together to prepare and protect critical infrastructure and key assets nationwide from terrorist events. Owners of critical facilities and infrastructure know that they are vulnerable to terrorism and have executed preparedness planning and exercises for years and fortified these facilities to minimize their vulnerability.

Environment: A terrorism event using a WMD could cause harm to the environment, but no platforms currently existing for estimating the level of harm. The best gauge of vulnerability of the environment

5.6.b
Packet Pg. 355 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 4: Hazard Identification and Risk Assessment 283 would be a review of damage from past terrorism events. Capturing such data from future events could be beneficial in measuring the vulnerability of the environment.

Economic: Economic impacts from a terrorist event could be significant. The cost of a terrorist act would be felt in terms of loss of life and property and disruption of business activity. Recovery would take significant resources and expense at the local level.

Terrorism Total Risk Score
Table 4-216 represents the terrorism Total Risk Score for the Contra Costa County, based on the Risk Assessment Methodology, as defined in this Plan.

Table 4-216. Terrorism Total Risk Score
Hazard
Event
Probability Consequence Total Risk
Probability
Factor Extent Vulnerability Impact ConsequenceScore
Total Risk
Score*
Terrorism
(Weapons of Mass Destruction) 1 18 11 27 56 31
Consequence: Sum of all weighted factors.

Extent: Sum of the weighted Extent factors.

Vulnerability: Sum of the weighted Vulnerability factors.

Impact: Sum of the weighted Impact factors.

The Total Risk Score is a measure of Probability and Consequence.

5.6.b
Packet Pg. 356 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 5: Mitigation Strategy 284
CHAPTER 5. MITIGATION STRATEGY
The heart of a Hazard Mitigation Plan is the Mitigation Strategy, which serves as the long-term blueprint for reducing the potential losses identified in the Hazard Risk Assessment. The Mitigation Strategy describes how the community will accomplish the overall purpose of the planning process. In this section, mitigation goals and objectives were reevaluated and updated; and mitigation actions were updated, identified, evaluated, and prioritized.

5.1 MITIGATION GOALS
In this section of the Plan, the Hazard Risk Assessment identified Conta Costa County is prone to 15 hazards (Table 4-1) – 10 natural and five (5) human-caused/technological. The Steering Committee and community stakeholders understand that although hazards cannot be eliminated altogether, the many communities within Contra Costa County can work together toward building disaster-resilient communities. Table 5-1 outlines a list of five (5) goals and 19 objectives. The goals represent the County’s long term and strategic vision to accomplish and achieve successful mitigation efforts. The associated objectives are specific strategies and steps identified to assist the communities in attaining the listed goals.

Table 5-1. Contra Costa County Mitigation Goals and Objectives Goals
1 Save (or protect) lives and reduce injury.
2 Increase resilience of infrastructure and critical facilities. 3 Avoid (minimize or reduce) damage to property.
4 Encourage the development and implementation of long-term, cost-effective, and environmentally sound mitigation projects.
5 Build and support capacity to enable local government and the public to prepare for, respond to and recover from the impact of natural hazards.

Objectives
Can be
Applied to
These Goals
1 Increase resilience of infrastructure and critical facilities. 1, 3, 5 2 Sustain reliable local emergency operations and facilities during and after a disaster. 1, 5 3 Inform the public on the risk from hazards of concern and increase awareness, preparation, mitigation, response, and recovery activities to promote public safety. 1, 3, 5 4 Minimize the impacts of known hazards on current and future land uses by providing incentives for hazard mitigation. 1, 3, 5
5 Prevent or discourage new development in hazardous areas or ensure that, if building occurs in high-risk areas, it is done in a way to minimize risk. 1, 3, 5 6 At the local government level, continually improve understanding of the location and potential impacts of hazards, using the best available data and science. 1, 2, 3, 4, 5 7 Encourage all development to meet applicable standards for life safety. 1, 2, 3, 5 8 Monitor plan progress annually to integrate the local hazard mitigation plan with the results of disaster and hazard specific planning efforts. 1, 2, 3, 5 9 Promote development and use of floodplain management best practices through programs (e.g., Community Rating System). 3, 4, 5

5.6.b
Packet Pg. 357 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 5: Mitigation Strategy 285
Objectives
Can be
Applied to
These Goals
10 Provide or improve flood protection with flood control structures and drainage maintenance plans. 2, 3, 4
11 Enhance codes and their enforcement where feasible, so that new construction can withstand the impacts of known hazards and to lessen the impact of development on the environment’s ability to absorb the impact of natural hazards. 1, 3
12 Consider the impacts of known hazards in all planning mechanisms that address current and future land uses within the planning area. 1, 3 13 Eliminate or minimize disruption of local government operations caused by known hazards. 1, 3, 4
14 Consider open space land uses within identified high-hazard risk zones. 1, 2, 3, 4, 5 15 Retrofit, acquire, or relocate identified high-risk structures, including those known to experience repetitive losses. 1, 3, 4
16 Establish a partnership among all levels of government and the business community to improve and implement methods to protect property. 1, 2, 3, 4, 5 17 Encourage hazard mitigation measures that promote and enhance natural processes and minimize adverse impacts on the ecosystem. 2, 3, 4
18 Promote and implement hazard mitigation plans and projects that are consistent with state, regional, and local climate action and adaptation goals, policies, and programs. 1, 2, 3, 4, 5 19 Identify and implement inclusive actions that reduce vulnerability for Contra Consta County residents and visitors. 1

5.2 MITIGATION STRATEGIES AND ACTIONS
Plan participants assessed hazard mitigation actions, including actions from FEMA guidance documents, the 2018 Contra Costa County Hazard Mitigation Plan, and suggestions from participating communities and their respective stakeholders during a series of workshops and public meetings that took place throughout the County in December 2023. Supporting documentation for stakeholders and public engagement can be found in Appendix B and C, respectively. A summary of Unincorporated Contra Costa County’s mitigation actions status is listed in Table 5-2 and all mitigation actions can be found in Appendix A.

Mitigation actions and status for each plan participant can be found in their respective annexes.

5.6.b
Packet Pg. 358 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 5: Mitigation Strategy 286
Table 5-2. Contra Costa County Mitigation Actions Summary Status Mitigation Action Total
Ongoing 13
In Progress/In Work 6
Not Started 2
Delayed/Deferred 1
New 25
TOTAL 47
Completed 8
Deleted/No Longer Needed 1
Mitigation Actions per Natural Hazard
Climate Change 21 Landslide 18
Dam and Levee Failure 17 Sea Level Rise 22
Drought 17
Severe Weather
(Severe Thunderstorms (hail, strong winds, and tornadoes), Heavy Rainfall, Heat Wave)
20 Earthquake 25 Tsunami 19
Flood 33 Wildfire 26
The mitigation actions in Volume 1 and each jurisdiction’s annex are organized as follows:

New Mitigation Actions: New actions identified during this plan development process.

Ongoing Mitigation Actions: These ongoing actions were included in the previous update and have no definitive end. During this Plan update, the ongoing mitigation actions were modified and/or amended, as needed, to better define the action.

In Progress/In Work: These actions were included in the previous update and are underway during this Plan update. These actions have not been completed but are in progress.

Completed Mitigation Actions: Completed actions since the previous plan iteration.

Not Started Mitigation Actions: These actions were included in the previous update but have not been started. During this Plan update, these mitigation actions were modified and/or amended, as needed, to better define the action.

Deferred/Delayed Mitigation Actions: Actions are deferred when risk cannot be validated, or additional time is needed to validate the potential impacts and benefits of the action.

Deleted/No Longer Needed Mitigation Actions: These actions are no longer relevant or applicable because other mitigation actions addressed the mitigating need, or the hazard vulnerability changed resulting in reduced risk.

5.2.1. Mitigation Action Plan
The Mitigation Action Plan helps prioritize mitigation initiatives according to a benefit cost analysis of the proposed actions and their associated cost. Additionally, the Action Plan provides the framework for how

5.6.b
Packet Pg. 359 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 5: Mitigation Strategy 287
the proposed actions and initiatives will be implemented and administered by Contra Costa County and each plan participant over the next five (5) years. The parameters (i.e., estimated cost, benefits, duration, and prioritization) that will be used for the prioritization and benefit cost analysis of each mitigation action are outlined in this section

5.2.1.1. Mitigation Action Benefit Cost Review
While the preference is to provide definitive costs (i.e., dollar figures) for each mitigation action, this is not realistic for every mitigation action without project scoping or engineering studies. Therefore, a review of the apparent benefits versus the apparent cost of each project was performed. Parameters were established for assigning subjective ratings (i.e., high, medium, and low) to the costs and benefits of these projects. The estimated cost and benefits parameters are defined in Table 5-3 and Table 5-4, respectively.

Table 5-3. Mitigation Action Estimated Cost Parameters
Rating Parameter
High Existing funding will not cover the cost of the project; implementation would require new revenue through an alternative source (e.g., bonds, grants, and fee increases).

Medium
The project could be implemented with existing funding but would require a re-apportionment of the budget or a budget amendment, or the cost of the project would have to be spread over multiple years.

Low The project could be funded under the existing budget. The project is part of or can be part of an ongoing existing program.

Table 5-4. Mitigation Action Benefits Parameters
Rating Parameter
High Project will provide an immediate reduction of risk exposure for life and property.

Medium Project will have a long-term impact on the reduction of risk exposure for life and property, or project will provide an immediate reduction in the risk exposure for property.

Low Long-term benefits of the project are difficult to quantify in the short term.

5.2.1.2. Mitigation Action Project Duration
While the preference is to provide definitive project completion dates, this is not realistic for all mitigation actions. Therefore, the parameters for the project duration (i.e., estimated completion date) are listed in Table 5-5.

Table 5-5. Mitigation Action Project Duration Parameters Rating Parameter
Short Term To be completed in one (1) to five (5) years.

Long Term To be completed in more than five (5) years.

Ongoing Currently being funded and implemented under existing programs, and/or is seeking funding and necessary approvals.

5.2.1.3. Mitigation Action Prioritization
Existing Mitigation Actions
The mitigation actions must be prioritized according to the benefit cost analysis of the proposed projects and their associated costs (44 CFR, Section 201.6(c)(3)(iii)). The benefits of proposed actions were weighted against multiple factors as part of the project prioritization process. The benefit cost analysis

5.6.b
Packet Pg. 360 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 5: Mitigation Strategy 288
was not of the detailed variety required by FEMA for project grant eligibility under the Hazard Mitigation Grant Program (HMGP) and Building Resilient Infrastructure and Communities (BRIC) Program. A less formal approach was used because some actions may not be implemented for up to 10 years, and associated costs and benefits could change dramatically in that time.

Existing mitigation actions were prioritized based on the parameters outlined in Table 5-6.

Table 5-6. Existing Mitigation Action Priority Parameters Priority Parameter
High
An action that meets multiple goals (i.e., multiple hazards), has benefits that exceed cost, has funding secured or is an ongoing project and meets eligibility requirements for the Hazard Mitigation Grant Program (HMGP) or Pre-Disaster Mitigation (PDM) grant program. High priority projects can be completed in the short term (one (1) to five (5) years).

Medium
An action that meets goals and objectives, that has benefits that exceed costs, and for which funding has not been secured but that is grant eligible under HMGP, PDM or other grant programs. Project can be completed in the short term once funding is secured. Medium priority projects will become high priority projects once funding is secured.

Low
An action that will mitigate the risk of a hazard, that has benefits that do not exceed the costs or are difficult to quantify, for which funding has not been secured, that is not eligible for HMGP or PDM grant funding, and for which the timeline for completion is long term (one (1) to 10 years). Low priority projects may be eligible for other sources of grant funding from other programs.

New Mitigation Actions
New mitigation actions were evaluated by each plan participant with the following STAPLEE+E method.

This method utilizes eight (8) criteria for evaluating a mitigation action – Social, Technical, Administrative, Political, Legal, Economic, Environmental, and Equity and within each of those criteria are additional considerations. Table 5-7 outlines an explanation of how each of the STAPLEE+E criteria may be applied to the evaluation of each mitigation action.

Table 5-7. STAPLEE+E Method
Criteria Description
S Social
Mitigation actions are acceptable to the community if they do not adversely affect a particular segment of the population, do not cause relocation of lower income people, and if they are compatible with the community’s social and cultural values.

Will the proposed action adversely affect one (1) segment of the population?
Will the action disrupt established neighborhoods, break up voting districts, or cause the relocation of lower income people? T Technical
Mitigation actions are technically most effective if they provide a long-term reduction of losses and have minimal secondary adverse impacts.

How effective is the action in avoiding or reducing future losses? Will it create more problems than it solves?
Does it solve the problem or only a symptom?
Does the Mitigation strategy address continued compliance with the National Flood Insurance Program (NFIP)?

5.6.b
Packet Pg. 361 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 5: Mitigation Strategy 289
Criteria Description
A Administrative
Mitigation actions are easier to implement if the jurisdiction has the necessary staffing and funding.

Does the jurisdiction have the capability (e.g., staff, technical experts, and/or funding) to implement the action, or can it be readily obtained? Can the community provide the necessary maintenance?
Can it be accomplished in a timely manner?
P Political
Mitigation actions can truly be successful if all stakeholders have been offered an opportunity to participate in the planning process and if there is public support for the action.

Is there political support to implement and maintain this action? Is there a local champion willing to help see the action to completion? Is there enough public support to ensure the success of the action? How can the mitigation objectives be accomplished at the lowest cost to the public?
L Legal
It is critical that the jurisdiction or implementing agency have the legal authority to implement and enforce a mitigation action.

Does the community have the authority to implement the proposed action?
Are the proposed laws, ordinances, and resolutions in place to implement the action?
Are there any potential legal consequences?
Is there any potential community liability?
Is the action likely to be challenged by those who may be negatively affected?
Does the mitigation strategy address continued compliance with the NFIP?
E Economic
Budget constraints can significantly deter the implementation of mitigation actions. It is important to evaluate whether an action is cost-effective, as determined by a cost benefit review, and possible to fund.

Are there currently sources of funds that can be used to implement the action?
What benefits will the action provide?
Does the cost seem reasonable for the size of the problem and likely benefits?
What burden will be placed on the tax base or local economy to implement this action?
Does the action contribute to other community economic goals such as capital improvements or economic development?
What proposed actions should be considered but be “tabled” for implementation until outside sources of funding are available?

5.6.b
Packet Pg. 362 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 5: Mitigation Strategy 290
Criteria Description
E Environmental
Sustainable mitigation actions that do not have adverse effect on the environment, comply with federal, state, and local environmental regulations, and are consistent with the community’s environmental goals, have mitigation benefits while being environmentally sound.

How will this action affect the environment (i.e., land, water, endangered species)?
Will this action comply with local, state, and federal environmental laws and regulations?
Is this action consistent with community environmental goals? E Equity
Does not create an opportunity for unequal distribution of resources; racism; affect a particular segment of the population, including communities of color, communities that face discrimination based on sex, sexual orientation or gender identity, individuals with disabilities, individuals who identify with certain religion, individuals with Limited English Proficiency, or rural communities, etc.

Is the action consistent and systematically fair?
New Mitigation Actions Priority
Priorities were assessed by requesting that every new mitigation action submitted by the plan participants be ranked by each of the eight (8) criteria factors (i.e., STAPLEE+E). Each criterion is evaluated on a scale from one (1) to five (5), with one (1) defined as strongly disagree and five (5) as strong agree.

Therefore, the highest favorable score would be 40, meaning the action scored five (5) in all eight (8) categories. Table 5-8 delineates how the STAPLEE+E prioritization score was used to prioritize each mitigation action.

Table 5-8. New Mitigation Action Priority Parameters
Priority STAPLEE+E Prioritization Score
High 30 – 40 points
Medium 19 – 29 points
Low 8 – 18 points
Mitigation actions with the highest scores represent those mitigation initiatives that represent the highest priority. In addition to the STAPLEE+E Method, the Steering Committee identified those actions that represented the greatest importance and priority to Contra Costa County’s plan participants. It should be noted that, although the STAPLEE+E Method provides a standardized process for assigning priority/importance across all participating jurisdictions, there may be additional factors and considerations that elevate the status of a particular mitigation action. This is why input from the Steering Committee is also an important consideration in this process.

5.3 CHANGES IN PRIORITY
A community’s mitigation priorities may change over time for a number of reasons. Addressing these changes allows a community to redirect actions that reflect current conditions, including financial and political realities, or changes in conditions or priorities following disaster event. Changes in the priority of a Hazard Mitigation Plan are often dynamic and reflect the evolving understanding of risk, the availability of resources, and the needs of the community. This helps ensure that the Plan remains relevant and

5.6.b
Packet Pg. 363 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 5: Mitigation Strategy 291
effective in reducing vulnerability to the hazards identified in the Plan by the community. Contra Costa County has identified the following changes in priorities for the 2024 Hazard Mitigation Plan:

There were no changes to the previous mitigation goals and objectives. However, an additional objective which focuses on identifying and implementing inclusive actions that reduce vulnerability for residents and visitors within Contra Costa County, including the underserved population.

Projects identified in the 2024 General Plan, as appropriate, were also included in this update of the Hazard Mitigation Plan to promote alignment across County plans and create the possibility for grant eligibility for those projects. The General Plan serves as the basis for planning and infrastructure related decisions made by County staff and decision makers; and it is built around the themes of environmental justice, community health, economic development, and sustainability. The General Plan was undergoing its update simultaneously with this Hazard Mitigation Plan.

Climate change was added as a new hazard and the effects of climate change in the severity of impacts were discussed for each natural hazard. Contra Costa County and its cities must reduce the amount of greenhouse gases that are emitted into the atmosphere from sources under the jurisdiction, while also adapting to the hazards associated to climate change – wildfires, floods, drought, and sea level rise. These four (4) hazards are profiled in this Plan. The County’s Climate Action Plan (CAP) 2024 update is the County’s strategic plan to reduce greenhouse gas emissions and to improve resilience to changing climate conditions in the County. The 2024 CAP implements the 2045 General Plan’s policy guidance and addresses behaviors, regulations, and investment decisions that directly reduce greenhouse gas emissions or promote climate resilience. This approach supports a holistic view of climate action planning and sustainability which works to reduce Contra Costa County’s contribution to climate change by mitigating greenhouse gas emissions while simultaneously preparing for the changes that cannot be avoided through adaptation strategies.

Envision Contra Costa 2040 is the County’s plan to address land use, transportation, housing, climate change, environmental justice, and other important issues over the next 20 years. At the time of this Hazard Mitigation Plan update, the 2045 General Plan and the 2024 Climate Action Plan were undergoing public comment. In an effort to integrate both of these plans into hazard mitigation, the outcomes of the extensive public outreach for the ongoing Envision Contra Costa 2040 process were incorporated into this Plan.
o The General Plan includes a Safety Element which includes all the hazards that impact the County; Community Profiles (for each unincorporated neighborhood) that identify the community’s local hazards; Impacted Communities where the population is exposed to hazards at higher levels than others; and policies and actions.

There are 13 new plan participants – three (3) municipalities and 10 special districts. The new plan participants include – City of Clayton, City of Oakley, City of Pinole, Mt. View Sanitary District, Reclamation District No. 799, Reclamation District No. 2025, Reclamation District No. 2026, Reclamation District No. 2065, Reclamation District No. 2122, Reclamation District No. 2137, Rodeo-Hercules Fire Protection District, Town of Discovery Bay Community Services District, and West County Wastewater District.

All mitigation actions from the previous Plan were updated, and a more concerted effort on achieving equitable outcomes for all communities, including underserved communities and socially vulnerable populations, has been implemented.

There were some notable changes to the hazard risk ranking.

5.6.b
Packet Pg. 364 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 5: Mitigation Strategy 292
o The new methodology includes 14 factors (versus four (4) in the 2018 update) which align with FEMA’s risk assessment criteria. Refer to Section 4.3 for further details on the 2024 risk assessment methodology.
o Severe weather hazards were ranked individually and not as a whole category. Heavy rainfall, strong winds/damaging winds, severe thunderstorms, heat wave/extreme heat, and tornado were ranked individually even though these are grouped under severe weather in the hazard profile.
o Riverine/creek flooding and urban/flash flooding were ranked individually even though these are grouped under the flood hazard profile.
o Technological hazards and human-caused hazards were included in the hazard ranking. o In the 2024 ranking, wildfire is ranked as high risk (ranked medium in the previous ranking) and drought is ranked medium (ranked low in the previous ranking). Although all the hazards under severe weather were ranked as medium risk (except tornado which was ranked as low), heavy rainfall was ranked high. Severe weather was ranked medium in the previous Plan.

5.6.b
Packet Pg. 365 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 6: Plan Maintenance 293
CHAPTER 6. PLAN MAINTENANCE
The Disaster Mitigation Act of 2000 requires the monitoring, evaluation and updating of the hazard mitigation plan every five (5) years. This Hazard Mitigation Plan is designed to be a “living” document and therefore will be reviewed and updated within five (5) years from its approval date. The Contra Costa County Hazard Mitigation Steering Committee will provide leadership and guidance throughout the Plan’s life cycle (i.e., monitoring, evaluating, and updating). Updates will allow municipal leaders and the public to provide input into the process. The public will be notified of this opportunity via legal public notices.

The Plan maintenance process includes a schedule for annual monitoring and evaluation of the programmatic outcomes established in the Plan and for producing a formal Plan revision every five (5) years.

6.1 PLAN UPDATE
The Plan may be reviewed on an annual basis by Contra Costa County OES and reviewed and revised every five (5) years by the Contra Costa County Hazard Mitigation Steering Committee to determine the effectiveness of programs and to reflect changes that may affect mitigation priorities. Contra Costa County OES will be responsible for contacting the Steering Committee members and organizing the review. Members of the Steering Committee will be responsible for monitoring and evaluating the progress of the mitigation strategies in the Plan. Additionally, the goals and actions will be reviewed by the Steering Committee to determine their relevance to changing situations in the County as well as changes in Federal policy, and to ensure they are addressing current and expected conditions.

Furthermore, the Steering Committee will also review the hazard risk assessment portion of the Plan to determine if this information should be updated or modified, given any new available data. The organizations responsible for the various action items will report on the status of the projects, the success of various implementation processes, difficulties encountered, success of coordination efforts, and which strategies should be revised or removed.

Contra Costa County OES will be responsible for ensuring Plan updates. Also, Contra Costa County OES and the Steering Committee will notify all stakeholders and plan participants when changes have been made. Every five (5) years, the Plan will be updated and submitted to the State of California Office of Emergency Services and to FEMA Region 9 for review and approval.

6.1.1. Monitoring, Evaluating
To ensure the Contra Costa County Hazard Mitigation Plan continues to provide an appropriate path for risk reduction throughout the County, it is necessary to regularly evaluate and update it. Contra Costa County OES will be responsible for monitoring the status of the Plan and gathering mitigation action status reports from the appropriate parties. The Contra Costa County Hazard Mitigation Steering Committee will convene on an annual basis to determine the progress of the identified mitigation actions.

The Steering Committee will also be an active participant in the next Plan update. As this Plan matures, new stakeholders and/or plan participants will be identified and encouraged to join the existing Hazard Mitigation Steering Committee.

Contra Costa County OES is responsible for contacting Steering Committee members and organizing the annual meeting. During each annual meeting, the Steering Committee will be responsible for a brief evaluation of the 2024 Hazard Mitigation Plan and to review the progress on mitigation actions. Each annual meeting must be documented, including the plan evaluation and review of mitigation actions.

Mitigation actions have been formatted to facilitate the annual review process. Additional Hazard Mitigation Steering Committee responsibilities include, but are not limited to:

5.6.b
Packet Pg. 366 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 6: Plan Maintenance 294
Annually reviewing each goal and objective to determine its relevance and appropriateness.

Monitor and evaluate the mitigation strategies in this Plan to ensure the document reflects current hazard analyses, development trends, code changes, and risk analyses and perceptions.

Ensure the appropriate implementation of annual status reports and regular maintenance of the Plan. The Steering Committee will hear progress reports from the parties responsible for the various implementation actions to monitor progress.

Create future action plans and mitigation actions. These should be carefully assessed and prioritized utilizing the STAPLEE+E Method outlined in the Mitigation Strategy section of this Plan.

Ensure the public is invited to comment and involved in mitigation plan updates.

Ensure that Contra Costa County complies with all applicable Federal statutes and regulations during the periods for which it receives grant funding, in compliance with 44 CFR, Section 201.

Reassess the Plan in light of any major hazard event. The Steering Committee will convene within 45 days of any major event to review all applicable data and to consider the risk assessment, plan goals, objectives, and action items given the impact of the hazard event.

Review the Plan in connection with other plans, projects, developments, and other significant initiatives.

Coordinate with appropriate counties within Contra Costa County and authorities to incorporate regional initiatives that transcend the County boundaries.

Update the Plan every five (5) years and submit it to the State of California OES and FEMA Region 9 for approval.

Amend the Plan whenever necessary to reflect changes in state or federal laws and statutes required in 44 CFR, Section 201.

6.1.1.1. Continued Public Engagement
Contra Costa County OES is dedicated to involving the public directly in the review and updates of the Plan. The Steering Committee is responsible for the review and update of the Plan. The public will also have the opportunity to provide input into Plan revisions and updates. Copies of the Plan will be kept by the appropriate County departments, cities, towns, and special districts.

Public meetings will be held when deemed necessary by the Steering Committee. The meetings will provide a forum where the public can express concerns, opinions, or new alternatives that can then be included in the Plan. Contra Costa County OES will be responsible for using the appropriate resources to publicize the public meetings and maintain public involvement. To further facilitate continued public involvement in the planning process, Contra Costa County OES will ensure a copy of the Plan readily available for review and comment by the public. The Plan will also be available on the Contra Costa County website.

6.1.1.2. Implementation and Integration through Existing Plans and Programs Hazard mitigation practices must be incorporated within existing plans, projects, and programs.

Therefore, the involvement of all departments, private non-profits, private industry, and appropriate jurisdictions is necessary in order to find mitigation opportunities within existing or planned projects and programs. To execute this, the Steering Committee will assist and coordinate resources for the mitigation actions and provide strategic outreach to implement mitigation actions that meet the goals and objectives identified in this Plan.

5.6.b
Packet Pg. 367 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 6: Plan Maintenance 295
The Contra Costa County Hazard Mitigation Plan is integrated in external plans developed by other local agencies primarily as it relates to the Threat and Hazard Identification Risk Assessment (THIRA). The THIRA is conducted every five (5) years as part of the mitigation planning process. The results of the THIRA detail the risks posed by hazards within Contra Costa County. This information is shared with community partners and local jurisdictions, allowing other planning efforts to be based on the latest hazard information. As a result, local jurisdictions developing comprehensive land use plans integrate the hazard risk information into their efforts.

The Hazard Mitigation Plan is essential to understanding the hazards facing Contra Costa County, the resulting prioritized list of hazards is used across the suite of Contra Costa County and local jurisdictions plans, and community partner organizations, thus creating a shared understanding of the hazards facing the County.

The results of this Plan will be incorporated into ongoing planning efforts throughout the County. Contra Costa County, its municipalities and special districts will update zoning plans and related ordinances, as necessary, and as part of regularly scheduled updates. Each plan participant will be responsible for updating and integrating elements of the Plan into the community’s own respective community plans and ordinances.

6.1.1.3. The Five-Year Action Plan
This section outlines the implementation agenda that the Hazard Mitigation Steering Committee, led by Contra Costa County OES, should follow five (5) years after adoption of this Plan, and then every five (5) years thereafter.

The Steering Committee will consider the following action plan for the five (5) year planning cycle. It should be noted that the schedule on Table 6-1 can be modified as necessary and does not include any meetings and/or activities that would be necessary following a disaster event (e.g., reconvening the Hazard Mitigation Steering Committee within 45 days of a disaster or emergency to determine what mitigation projects should be prioritized during the community recovery). If an emergency meeting of the Hazard Mitigation Steering Committee occurs, this proposed schedule may be altered to fit any new needs.

5.6.b
Packet Pg. 368 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 6: Plan Maintenance 296
Table 6-1. Five-Year Action Plan
Year 0
2024 Update the 2018 Hazard Mitigation Plan and submit it to the State of California OES and FEMA Region 9 for approval.

Year 1
2025
Work on mitigation actions.

Contra Costa County OES will stay in contact with its key stakeholders and plan participants to keep track of project status.

Encourage Plan integration efforts.

Reconvene the Steering Committee for an annual meeting.

Discuss opportunities for Plan integration with other planning documents.

Discuss recent hazard events.

Update the status of projects.

Host public meetings to re-introduce the Plan to the community, identify additional hazards of concern that should be considered for the next update, if any, and provide update and obtain input on mitigation projects occurring within the community.

Year 2
2026
Work on mitigation actions.

Contra Costa County OES will stay in contact with its key stakeholders and plan participants to keep track of project status.

Encourage Plan integration efforts.

Reconvene the Steering Committee for an annual meeting.

Discuss opportunities for Plan integration with other planning documents.

Discuss recent hazard events.

Update the status of projects.

5.6.b
Packet Pg. 369 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Chapter 6: Plan Maintenance 297
Year 3
2027
Work on mitigation actions.

Contra Costa County OES will stay in contact with its key stakeholders and plan participants to keep track of project status.

Encourage Plan integration efforts.

Apply for hazard mitigation grant funds (e.g., HMGP, BRIC) to update the next iteration of the Hazard Mitigation Plan.

Reconvene the Steering Committee for an annual meeting.

Discuss opportunities for Plan integration with other planning documents.

Discuss recent hazard events.

Update the status of projects.

Year 4
2028
Work on mitigation actions.

Contra Costa County OES will stay in contact with its key stakeholders and plan participants to keep track of project status.

Encourage Plan integration efforts.

Update the 2024 Hazard Mitigation Plan and conduct a series of meetings with stakeholders, plan participants, and the public.

Year 5
2029
Update the 2024 Hazard Mitigation Plan and submit it to the State of California OES and FEMA Region 9 for approval.

Repeat.

5.6.b
Packet Pg. 370 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) APPENDIX A. MITIGATION ACTIONS

5.6.b
Packet Pg. 371 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 372 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 373 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 374 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason. (Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 375 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 376 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 377 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 378 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 379 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 380 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 381 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 382 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 383 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 384 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 385 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 386 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 387 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 388 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 389 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 390 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 391 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 392 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 393 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 394 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 395 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason. (Loss Avoided)
(If applicable)
(If applicable)
\ \
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 396 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 397 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 398 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 399 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 400 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 401 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 402 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 403 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 404 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 405 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 406 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason. (Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 407 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason. (Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 408 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 409 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 410 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 411 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 412 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 413 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 414 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 415 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 416 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 417 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 418 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 419 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason. (Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 420 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 421 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 422 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 423 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 424 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 425 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 426 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) If Deleted/No Longer
Needed, provide reason.
(Loss Avoided)
(If applicable)
(If applicable)
If Other, you must
identify a funding source. Please provide further
detail on Potential
Funding Source. (Optional)

5.6.b
Packet Pg. 427 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 355
APPENDIX B. STAKEHOLDER ENGAGEMENT
Contra Costa County engaged with various stakeholders on multiple occasions, to include the Steering Committee during meetings, workshops, and one on one meetings. These stakeholders assisted in identifying hazards, assessing risks and vulnerability, record critical facilities, and develop and prioritize mitigation actions. In addition to sharing technical data, reports, and studies. Contra Costa County understands the importance of stakeholder engagement and that their contribution strengthens the content and outcomes of this Hazard Mitigation Plan.

B.1. STAKEHOLDER AND JURISDICTION INTRODUCTORY WEBINARS A series of four (4) Stakeholder and Jurisdiction Introductory webinar were conducted virtually at the beginning stages of the 2024 Contra Costa County Hazard Mitigation Plan update. All potential plan participants and stakeholders (i.e., county and city representatives) were invited to participate in one (1) webinar. The purpose of this webinar was to provide valuable information regarding the FEMA Hazard Mitigation Program directive, and more importantly, demonstrate how participating in this Plan will enable each jurisdiction’s eligibility for FEMA’s Hazard Mitigation Assistance grant programs. The meeting agenda and sign in sheets for each webinar are below.

5.6.b
Packet Pg. 428 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 356
Webinar Agenda

5.6.b
Packet Pg. 429 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 357
September 25, 2024 – Webinar (Session 1) Sign In Sheets

5.6.b
Packet Pg. 430 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 358
September 27, 2023 – Webinar (Session 2) Sign In Sheets

5.6.b
Packet Pg. 431 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 359
October 3, 2023 – Webinar (Session 3) Sign In Sheets

5.6.b
Packet Pg. 432 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 360
October 4, 2023 – Webinar (Session 4) Sign In Sheets

5.6.b
Packet Pg. 433 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 361
B.2. STEERING COMMITTEE MEETING
A total of approximately 16 steering committee members were part of the Hazard Mitigation Plan update process. Table 1-3 in Section 1.5.2 (Steering Committee) outlines the Steering Committee members by jurisdiction/organization, name, and title of position. The first Steering Committee Meeting for the 2024 Contra Costa County Hazard Mitigation Plan update was conducted on November 1, 2023, and used an agenda to guide the meeting’s discussion. The meeting agenda and sign in sheets of the Steering Committee Meeting are below.

Steering Committee Meeting Agenda

5.6.b
Packet Pg. 434 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 362
Steering Committee Meeting Sign In Sheet

5.6.b
Packet Pg. 435 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 363
B.3. STAKEHOLDER WORKSHOP
Two (2) Stakeholder Workshops were held in the Contra Costa County Emergency Operation Center on December 4, 2023, and December 6, 2023. The workshops gave each local planning team an opportunity to work with Contra Costa County OES to identify local hazards and areas of concern, review previously identified mitigation actions, develop future mitigation projects, prioritize mitigation projects moving forward and update their jurisdiction’s annex of the 2024 Contra Costa County Hazard Mitigation Plan (HMP). The workshop agenda and sign in sheets are below. All participating jurisdictions were able to attend at least one (1) of the workshops.

Stakeholder Workshops Agenda

5.6.b
Packet Pg. 436 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) December 4, 2023 – Stakeholder Workshop (Session 1) Sign In Sheets

5.6.b
Packet Pg. 437 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion)

5.6.b
Packet Pg. 438 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion)

5.6.b
Packet Pg. 439 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion)

5.6.b
Packet Pg. 440 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) December 6, 2023 – Stakeholder Workshop (Session 2) Sign-In Sheets

5.6.b
Packet Pg. 441 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion)

5.6.b
Packet Pg. 442 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion)

5.6.b
Packet Pg. 443 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion)

5.6.b
Packet Pg. 444 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion)

5.6.b
Packet Pg. 445 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion)

5.6.b
Packet Pg. 446 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 374
B.4. MULTI-AGENCY COORDINATION MEETING
The Hazard Mitigation Plan update was presented and discussed during the Contral Costa County Operational Area Multi-Agency Coordination (MAC) meeting, which occurs monthly, on November 1, 2023. Table B-1 lists the MAC members by jurisdiction/organization, name, and title.

Table B-1. Multi-Agency Coordination (MAC) Members List Name Department Title
Aaron Osorio City of Richmond Fire Department Battalion Chief Adam Springer Contra Costa County Health Services - Hazardous Material Acting Assistant Director
Adeline Ford PBF Energy LLC Refinery Water Environmental Engineer A.J. "Tony" Semenza Community Awareness and Emergency Response Executive Director Alana Weissman Contra Costa County Animal Services Department Lieutenant Aaron McAlister Contra Costa County Fire Protection District Deputy Fire Chief Anthony Morales Contra Costa County Water District
Anthony Morefield City of Antioch Police Department Interim Chief Angelina Camacho Lone Tree Post Acute Skilled Nursing Facility Ann Elliot Contra Costa County Human Resources Department Director of Human Resources Allan Shields Contra Costa County Office of the Sheriff- Danville Police Department Chief of Police- Lieutenant
Aimee Vitug-Hom VistAbility Program Director
Jessica Azevedo City of Walnut Creek Permit Center Supervisor Ben Alldritt Contra Costa County Office of the Sheriff- Lafayette Police Department Chief
Baraka Carter CAL Fire Deputy Chief of Operations -
Santa Clara Unit
Steven Beall Rodeo Sanitary District District Manager
Bear Heartly Contra Costa County Department of Information Technology GIS Manager
Brian Helmick Contra Costa County Fire Protection District Fire Chief Brian Hill Pleasant Hill Police Department Police Chief Bill Reid County Veterans Service Office Department Head Agency Contact Bethel Island Municipal Improvement District General Manager Ben Keizer Contra Costa County Health Services EMS
Blake Johnson Bradford Reclamation District 2059 District Engineer Blanca Gutierrez Contra Costa Crisis Center- 211 211 Resource Manager Brian Leonard City of Pleasant Hill Police Department Lieutenant - Support Services Brian Musser Byron School District Maintenance and Operations Lead

5.6.b
Packet Pg. 447 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 375
Name Department Title
Bob Ferronato California Department of Transportation Maintenance Manager 1 Beatriz Portillo Contra Costa County Office of the Sheriff OES Emergency Planning Coordinator
Brad Mustard Caltrans District 4 Hazmat Manager
EMS Branch
Brandon Lum California Office of Emergency Services Maritime Intelligence Brian Balbas Contra Costa County Department of Public Works Director Brian Garcia National Oceanic and Atmospheric Administration Warning Coordination Meteorologist
Briana Taylor American Red Cross Board Member
Brooke Converse Contra Costa County Library Public Information Officer Brian Sliger Contra Costa County Office of the Sheriff Lieutenant - Courts Claudia Ramirez The Society of St. Vincent de Paul of Contra Costa County Executive Director
Carolyn Halstenson Contra Costa County Department of Public Works Purchasing Caryn Thornburg Tenet Health Director Plant Operations
Cliff Buxton City of San Ramon Emergency Management
Analyst
Alexandra McMullen Contra Costa County Hazardous Materials Programs Clerical Supervisor Chau Vo Contra Costa County Health Services
Christy Saxton Contra Costa County Health Services Director of Health, Housing and Homeless Services
Christine Koehne San Ramon Valley Unified School District Special Needs Liason/ Educational Services
Carol McCrary VistAbility Director of Operations
United Way Bay Area General Contact
Brian Craig Rodeo-Hercules Fire Department Fire Chief
Connie Sanders Contra Costa County Office of the Sheriff Lieutenant - Watch Commander
Colby LaPlace Solano County Environmental Health Sr. Hazardous Materials Specialist
Constance
Slessinger
Contra Costa County Employment & Human
Services Department Manager, Procurement & Fleet
Caitlin Sly Meals on Wheels Executive Director
Chris Wynkoop City of Pinole Fire Department Fire Chief Cora Young Contra Costa County Employment & Human
Services Department
Emergency and Safety
Coordinator
Dally Aleman Contra Costa County Department of Public Works Purchasing Dan Peddycord Contra Costa County Health Services Chief Climate & Health Policy Officer
Dante Nomellini Jr. Central Delta Water Agency

5.6.b
Packet Pg. 448 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 376
Name Department Title
David Brockbandk Contra Costa County Department of Conservation and Development Principal Planner
David Cook East Bay Municipal Utility District Manager of Security and Emergency Preparedness
David Despain Caltrans (Department of Transportation) Maintenance Manager II David Woodard East Bay Municipal Utility District Manager, Regulatory Compliance
Danielle Bell San Ramon Valley Fire Protection District Community Risk Reduction Educator / CERT Coordinator
David Biggs City of Orinda City Manager
Dave Christensen Milestone California-Based Investment Company Co-Founder and Managing Principle
Denton Carlson City of San Ramon Captain - Virtual SRPD Dean Colombo Crockett-Carquinez Fire Department Fire Chief Debi Cooper Contra Costa County Clerk-Recorder Clerk-Recorder and Registrar of Voters
Debra Strawther Delta View Post Acute Care Skilled Nursing Facility Desbele Gebre Contra Costa County Department of Public Works Senior Buyer David Hall Contra Costa County Office of the Sheriff Captain - Training Mike Alvarez Reclamation District District Manager
Michael Butier California Department of Social Services - Disaster Services Branch State FAST Coordinator
Diane Maltester Contra Costa Interfaith Coalition & Council Chair Daniel Mcnamara San Ramon Valley Fire Protection District SRM Battalion Chief David Nielson Contra Costa County Office of the Sheriff Communications Contra Costa County Health Services
Doug Pittman City of Martinez Emergency Management
Analyst
Doug Pittman City of San Pablo Police Department Emergency Services Manager Deanne Pearn Contra Costa Crisis Center - Hope Solutions Executive Director David Peters Dublin San Ramon Services District Safety Officer Dennis Rein Moraga-Orinda Fire District Public Information Officer David Shroer City of Brentwood Police Department Police Lieutenant Dave Winnacker Moraga Orinda Fire Fire Chief
Dylan Radke Contra Costa County Council
Emelia Gabriele Contra Costa County Employment & Human
Services Department
Director of Administration
Services
Mark Jelonek Chevron Refinery Division Chief of Emergency Response/Planning/Training
Eric McQuoid Contra Costa County Office of the Sherriff OES Captain

5.6.b
Packet Pg. 449 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 377
Name Department Title
Enid Mendoz Contra Costa County CAO Senior Deputy CAO
Eric Presser MOTCO Military Ocean Terminal Concord Emergency Manager Erika Jenssen Contra Costa County Health Services Deputy Director Erinn Riley Contra Costa County Office of the Sheriff
911 County
Coordinator/Dispatch
Supervisor
Rev. Will McGarvey Interfaith Council of Contra Costa County Executive director Kevin Finn Central Contra Costa Transit Authority Procurement Garrett Thomsen California Office of Emergency Services Coastal Region Response Geoffrey Martin Contra Costa Health Services - Emergency Medical Services Pre-Hospital Care Coordinator
Gred Kogler City of Pleasant Hill Police Department Captain Glen Kimball Contra Costa County TV Community and Media Relations Specialist
Greg Baer Contra Costa County Department of Public Works Director of Airports Glorian Sasser Moraga-Orinda Fire District Administrative Services Director
Food Bank of Contra Costa and Solano
Major Gwyn Jones Concord Corps. - The Salvation Army Commanding Officer Huma Abbasi Chevron Chief Medical Officer
Heather Hackett Futures-Explored
Heidi Benenson East Bay Municipal Utility District
Emergency Preparedness and
Business Continuity
Administrator
Nate Hershey MBK Engineers - Reclamation Districts 830, 2025, 2026, 2137 District Engineer
Hannah Michaelson The Care Parent Network Program Director Ilana Israel-Samuels San Ramon Valley Unified School District Public Information Officer Jonas Aguiar San Ramon Valley Fire Protection District Battalion Chief James Lambert The Permanente Medical Group Service Line Director Jane Andriotti Contra Costa County Animal Services Department Captain / Field Services Unit Brian Janowiak BMK Engineers Supervising Engineer
Jason Crapo Contra Costa County Department of Conservation and Development
Deputy Director (Building
Division)
James Barnhill Crockett Community Services District Sanitary Department Manager Joe Bingaman City of Pinole Public Works Manager
Jennifer Cannon Contra Costa County Office of the SheriffCommunity Warning System Emergency Planning
Coordinator-CWS
Jose Castrejon City of El Cerrito Fire Department Battalion/Training Chief, Fire Operations

5.6.b
Packet Pg. 450 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 378
Name Department Title
Julie Cavallero Contra Costa County Office of the SheriffCommunity Warning System Community Warning System
Manager
John Cornell City of Lafayette Police Department Police Services Assistant Jeff Krieger City of Concord Police Department Lieutenant Jennifer Hopkins Contra Costa County Department of Information Technology
Assistant Chief Information
Officer
Jeremy Hough John Muir Health Director
Jeremy Rogers City of Pinole Community Services Director John Fortner City of Antioch Police Department Lieutenant Jeff Gove Bay Area Air Quality Management District Director of Compliance and Enforcement
James Ferris P66 Rodeo Refinery Fire Chief
James Matzorkis Port of Richmond Executive Director
Jeff Isaacs Moraga-Orinda Fire District Fire Marshal
James Larot Contra Costa Water District Operations Control Administrator
John Kan Lee Regional Center of the East Bay Emergency Coordinator Specialist
Jimmy Lee Contra Costa County Office of the Sheriff Public Information Officer J.B Morris Food Bank of Contra Costa and Solano Logistics Manager Joanne.Chiu Contra Costa County Department of Conservation and Development
Senior Planner, East Contra
Costa County Habitat
Conservancy
Jocelyn LaRocque Contra Costa County Department of Public Works Division Manager Jocelyn Stortz Contra Costa County Environmental Health Director of Environmental Health
Jody London Contra Costa County Department of Conservation and Development Sustainability Coordinator
Joe Yee Contra Costa County Department of Public Works Deputy Director John Cunningham Contra Costa County Department of Conservation and Development Transportation Planner
John F. Jones CocoKids Executive Director
John Wiggins Contra Costa County Environmental Health Supervising Environmental Health Specialist
Joseph Bateman Valero Energy Corporation Operations Supervisor Joe Piro Contra Costa Water District Response Project Manager Independent Living Resources
Josph Vasquez Hercules Police Department Chief
Karl Fischer Contra Costa County Health Services Community and Media Relations Specialist
Kelly Batson United Way Bay Area Senior Administrator

5.6.b
Packet Pg. 451 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 379
Name Department Title
Kelly Kalfsbeek Contra Costa County Department of Public Works Community and Media Relations Coordinator
Katie Haun Athoc/Blackberry Account Relations Manager
Kim McCarl Contra Costa County Health Services Communications Officer Kevin Janes City of El Cerrito Fire Department Battalion Chief Kristi Jourdan Contra Costa County Office of Communications and Media
Director, Office of
Communications and Media
Kristian Lucas Contra Costa County Health Services Assistant Director of Environmental Health
Lara DeLaney Contra Costa County CAO Senior Deputy County Administrator
Lavonna Martin Contra Costa County Health Services Deputy Director of Health Services
Lesley Garcia Contra Costa Crisis Center - 211 Contra Costa Director of Programs Lewis Broshard Contra Costa County Fire Protection District Fire Chief Lon Goestch Contra Costa County Fire Protection District Assistant Fire Chief - C Shift Lorena Herrera Contra Costa County Office of the Sherriff OES Senior Emergency Planning Coordinator
Lissette Davis Contra Costa County Office of Communications and Media
Community and Relations
Specialist
Liz Dietz Red Cross
Disaster Health Services
Manager / Disability Integration
Regional Lead
Lucas Lambert Moraga-Orinda Fire District Battalion - Chief Lynn Mackey Contra Costa Office of Education County Superintendent of Schools
Leslie Monroy Contra Costa County Office of the SheriffCommunity Warning System Emergency Planning
Coordinator-CWS
Les Putnam Pacific Gas & Electric Public Safety Specialist Lucy Zhou City of Richmond Port Marketing/ Operations
Manager
Lulis Lopez Contra Costa County Treasurer-Tax Collector Contra Costa County Auditor Controllers Office
Mark Whitlock BI Safety Committee
Manly Moulton City of Richmond Fire Department Battalion Chief Marc Shorr Contra Costa County Department of Information Technology Chief Information Officer
Marianne Iversen Down Syndrome Connection of the Bay Area Director of Teen and Adult Services
Marshall Bennett Contra Costa County Health Services - Emergency Services
Director of Emergency Medical
Services
Mathais Wakefield California Department of Social Services Matt Kaufmann Contra Costa County Health Services Deputy Director Matthew Slattengren Contra Costa County Agriculture / Weights and Measures
Ag Commissioner/Weights and
Measures Director

5.6.b
Packet Pg. 452 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 380
Name Department Title
Maureen Toms Contra Costa County Department of Conservation and Development
Deputy Director, Policy
Planning
Matt Avery City of Pinole Police Department Public Information Officer Lieutenant
Megan Benveniste Contra Costa County Office of the Sherriff OES Clerk Michael Casten Contra Costa County Office of the Sheriff Undersheriff Joshua McMurray City of Oakley City Manager
Micki Cronin City of Orinda Sr. Management Analyst
Rebecca Melvin City of Walnut Creek
Office Specialist - Risk
Management, Emergency
Management, City Attorney's
Office
Maria Lupita
Mendoza Sutter Delta Medical Center Safety Officer
Michael Brill BART Police Department Manager of Emergency Preparedness
Michael Callanan Contra Costa County Health Services CORE Outreach Coordinator Michael Dossey Contra Costa County Health Services - Hazardous Material
Accidental Release Prevention
Engineer
Michael Miller Martinez Refining Company Fire Department Fire Chief/Safety Supervisor Michael Tognolini East Bay Municipal Utility District Director of Water and Natural Resources
Michelle Heckle University of San Francisco
Division Commander -
Homeland Security Emergency
Management
Michael Hendley Capitol Corridor Joint Powers Authority Transportation Services Manager
Scott Mitchell County Connection Chief Operating Officer Mark Johnson Contra Costa County Office of the Sheriff Lieutenant Melissa Klawuhn Contra Costa County Office of the Sherrif Assistant Sheriff Monica Nino Contra Costa County Clerk Administrators Office Chief Officer Morgan March DOIT County GIS GIS Technician
Mike Quesada Contra Costa County Fire Protection District A Shift Duty Officer Mark Bennett Martinez Refinery Safety Supervisor
Meera Sreenivasan Contra Costa Health Services
Deputy Health Officer /
Communicable Disease
Controller
Monica Stoeffl California Resiliency Alliance Executive Director Marla Stuart Contra Costa County Department Employment & Human Services Department Director
NWS - SF Bay Area National Weather Service Meteorologist Miki Tsubota Contra Costa Water District Director of Public Works Nancy Navarro PBF Energy Security Manager

5.6.b
Packet Pg. 453 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 381
Name Department Title
Natalie Manier American Red Cross Disaster Program Manager Danielle Navarro City of Oakley Assistant City Manager
Neil Baranik Solvay Process Engineer
Nicole Benty CAL Fire Diablo Battalion Battalion Chief
Nicole Heath Contra Costa County Health Services Acting Director of Hazardous Materials Programs
Nate McCormack Town of Danville Emergency Services Manager Noah Brownlow City of Richmond Fire Department Battalion Chief Nanette Wellman Contra Costa County District Attorney DA Manager of Law Offices Ori Tzvieli Contra Costa County Health Services Health Officer/Public Health Director
Patti Tran California Department of Social Services Mass Care and Shelter Coordinator
Paul Keith El Cerrito Police Department Chief
Patrick Salmaid City of Martinez Police Department Lieutenant Pace Stokes Alameda County Sheriff's Office of Emergency Services Captain
Jeanet Lara Moraga Public Works Senior Administrative Assistant Rebecca Ramirez Rodeo-Hercules Fire Protection District Fire Chief Ryndie Azevedo City of Walnut Creek Risk Management Administrative Analyst 1 Regina Espinoza Bethel Island Municipal Improvement District District Manager Rich McEachin City of Clayton Police Chief
Rick Kovar Contra Costa County Office of the Sherriff OES Emergency Services Manager Ron Marley San Ramon Valley Fire Protection District Emergency Preparedness Coordinator
Ramsay Mashy California Autism Foundation Director of Quality Assurance and Community Services
Rob Thompson Westcat Public Transportation Services General Manager Robbie Morris Corteva Agriscience ER&S Specialist/Fire Chief Independent Living Resources
Ronald Maria California State Lands Commission Assistant Chief Marine Environmental Protection
Bret Prebula City of Clayton Interim City Manager
Ronda Boler Contra Costa County Treasurer-Tax Collector Executive Secretary to the Treasurer - Tax Collector
Ron Halog ILRSCC (Independent Living Resources Solano and Contra Costa County
Emergency Preparedness
Coordinator
Ryan Sullivan City of Orinda Police Chief
Russ Norris City of Concord Police Department Sergeant

5.6.b
Packet Pg. 454 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 382
Name Department Title
Russell Milburn Contra Costa County Department of Public Works Airport Division
Assistant Director of Airports -
Operations
Russell Watts Contra Costa County Treasurer Treasurer-Tax Collector Ruth Adams Contra Costa County Health Services Branch Coordinator Ruth Raisner Contra Costa County Health Services Medical Countermeasures Coordinator
Steve Albanese City of Pittsburg Police Department Captain Salma Sadiq Contra Costa County Human Resources Department Employee Benefits Analyst Scott Joseph Chevron Refinery Fire Fighter
Steve Devine City of Martinez Senior Management Analyst Shanon Winston Contra Costa County Risk Management Safety Services Specialist Shasa Curl City of Richmond City Manager
Shirell Naidu California Department of Social Services
Emergency Services
Coordinator / Regional Mass
Care Coordinator for Region II
Shawn Knapp Moraga Public Works Director of Public Works, Town Engineer
Sefanit Mekuria Contra Costa County Health Services Deputy Health Director Sonnet Rodriguez Reclamation District 800 (Byron Tract) District Manager Stan Massie American Red Cross Leadership Council Chair Stephen W. Griswold
III Office of Supervisor Diane Burgis District Representative Stephen Terrin Metropolitan Transportation Commission Emergency Coordinator Steve Burdo Contra Costa County Animal Services Department Public Information Office Public Information
Officer Contra Costa County Fire Protection District Public Information Officer Susan Vasquez City of Antioch Principal Executive Assistant City Manager’s Office
Terrence Cotcher East Bay Regional Park District Lieutenant of Police Ted Asregadoo Contra Costa District Attorney's Office Public Information Officer Tish Gallegos Employment & Human Services Department Community Relations/Media Division Manager / PIO
Tim Jenson Contra Costa County Department of Public Works Assistant Public Works Director Timothy Ellsworth Contra Costa County Health Services Environmental Health Specialist
Tim Ewell Contra Costa County CAO Chief Assistant County Administrator
Tim Herbert City of Brentwood Police Department Captain Todd Fitsimmons Contra Costa County Department of Conservation and Development Senior Planner
Trish Beirne City of Concord Emergency & Volunteer
Services Manager

5.6.b
Packet Pg. 455 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 383
Name Department Title
Uriel Diaz Tri Delta Transit
Special Projects Analyst/
Emergency Operations Center
Manager
Warren Lai Contra Costa County Department of Public Works Deputy Director Zuna Baker Portillo City of Pittsburg Environmental Health and Safety Officer
Lilia Corona Mountain View Sanitary District General Manager Lance Littlejohn Contra Costa County VOAD VOAD Lead
Cole Robyn California Office of Emergency Services Emergency Services Coordinator

5.6.b
Packet Pg. 456 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 384
B.5. WHOLE COMMUNITY
Contra Costa County provided key stakeholders an opportunity to be involved in the planning process.

This included, but was not limited to, sharing information and input to inform the Plan’s content; assist with targeted outreach and engagement, especially for the underserved communities; and review and feedback on the Plan during the plan comment period. Stakeholders are individuals or groups that a mitigation action or policy affects and involving them in the planning process helps obtain support for the Plan and identify barriers to carry out hazard mitigation.

The following stakeholder types were provided an opportunity to be part of the planning process.

Local and regional agencies involved in hazard mitigation activities (e.g., public works, emergency management, local floodplain administration and GIS departments).

Agencies that have the authority to regulate development (e.g., zoning, planning, community and economic development departments, building officials, planning, commissions and other elected officials).

Neighboring communities (e.g., adjacent local governments, including special districts and tribes, that are affected by similar hazard events. They also may share a mitigation action or project that crosses jurisdictional boundaries).

Businesses, academia, and other private interests (e.g., private utilities, chambers of commerce, dam owners, local or regional educational centers within the jurisdiction, or major employers that sustain community lifelines).

Nonprofit organizations, including community-based organizations that work directly with and/or provide support to underserved communities and socially vulnerable populations (e.g., faithbased organizations, disability agencies or non-governmental organizations, rural support agencies, health and social services departments, housing agencies and housing advocacy groups.

The stakeholders that were provided an opportunity to participate in the planning process, including review and feedback of the draft Plan, for the Contra Costa County Hazard Mitigation Plan are listed below in no particular order.

Local and Regional Agencies
Alameda County Sheriff’s OES Contra Costa County Mosquito and Vector Control District
Bay Area Air Quality Management District Contra Costa County Office of Communication and Media
Cal OES Contra Costa County Office of Education
CalFire Contra Costa County Office of Restorative Equity and Social Justice
California Department of Parks and Recreation Contra Costa County Office of the Sheriff California Department of Social Services Contra Costa County Probation California Department of Transportation
(Caltrans) Contra Costa County Risk Management

5.6.b
Packet Pg. 457 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 385
Local and Regional Agencies
California Department of Water Resources Contra Costa County Transportation Authority California Highway Patrol Contra Costa County Treasurer-Tax Collector California State Lands Commission Contra Costa County Veteran Services Office Capitol Corridor Joint Powers Authority Contra Costa County Volunteer Organizations Aiding in Disaster
Central Delta Water Agency Contra Costa County Water District Contra Costa County Administrator’s Office Contra Costa Regional Medical Center Contra Costa County Airport Dublin San Ramon Services District Contra Costa County Animal Services
Department East Bay Municipal Utility District
Contra Costa County Auditor – Controller East Bay Regional Park District Contra Costa County Clerk-Recorder Golden Gate, Bridge, Highway and Transportation District
Contra Costa County Counsel Metropolitan Transportation Commission Contra Costa County Department of Agriculture Military Ocean Terminal Concord Contra Costa County Department of
Conservation and Development National Oceanic and Atmospheric Association Contra Costa County Department of Information
Technology National Weather Service
Contra Costa County Department of Public
Works Rodeo Sanitary District
Contra Costa County District Attorney’s Office State Water Resources Control Board Contra Costa County Employment & Human
Services Department Tri Delta Transit
Contra Costa County Health Services West Contra Costa Transit Authority Contra Costa County Human Resources
Department WestCAT
Contra Costa County Library
Agencies that have the Authority to Regulate Development Contra Costa County Department of Conservation
Development Contra Costa Local Agency Formation Commission Neighboring Communities
Alameda County Bouldin Island Reclamation District
City of Antioch Reclamation District No. 2059 (Bradford Island) City of Concord Byron-Bethany Irrigation District
City of Pittsburg Crockett Community Services District
Marin County Crockett-Carquinez Fire Department

5.6.b
Packet Pg. 458 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 386
Neighboring Communities
Sacramento County Moraga-Orinda Fire District
San Joaquin County Reclamation District No. 800 (Byron Tract) Solano County
Yolo County
Nonprofit Organizations
American Red Cross Futures Explored
California Autism Foundation Independent Living Resources – Solano and Contra Costa Counties
California Resiliency Alliance Inter-Tribal Council of California Care Parent Network La Familia Counseling
CARESTAR Foundation Loaves and Fishes – Contra Costa County Carlton Senior Living Meals on Wheels
CocoKids Monument Crisis Center
Community Awareness and Emergency Response Regional Center of the East Bay Concord Corps. – The Salvation Army Richmond Community Foundation Contra Costa County Crisis Center - 211 Society of St. Vincent de Paul of Contra Costa County Contra Costa County Crisis Center – Hope Solutions United Way Bay Area Interfaith Council of Contra Costa County VistAbility
Down Syndrome Connection of the Bay Area
Businesses, Academia, and Other Private Organizations
AC Transit Global Medical Response
Amtrak John Muir Behavioral Health
AtHoc/Blackberry Kaiser Permanente Hospital
Bloomfield Cherries Lone Tree Post Acute Skilled Nursing Facility BMK Engineers Marathon Petroleum
BNSF Railway Martinez Refinery Company/PBF Energy
Brenden Theater Milestone California-Based Investment Company Byron School District MV Transportation
California State University Pacific Gas & Electric
Canyon Elementary School ** Philips 66 Rodeo Refinery
Chevron Refinery Shell Oil Company

5.6.b
Packet Pg. 459 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix B: Stakeholder Engagement 387
Businesses, Academia, and Other Private Organizations
Contra Costa County Community College District Sutter Delta Medical Center Contra Costa Event Park – Contra Costa County Fair Tenet Health Corteva University of San Francisco
County Connection Transportation and Link
Paratransit Services Valero Energy Corporation
Delta View Post Acute Care Skilled Nursing Facility Vituity EcoServices
Food Bank of Contra Costa and Solano

5.6.b
Packet Pg. 460 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 388
APPENDIX C. PUBLIC ENGAGEMENT
The mitigation planning process promotes awareness of hazard risks and continues the conversation about the community’s safety and resilience. A hazard mitigation plan generates additional community support when it accurately reflects the values and priorities of the community which will lead to successfully implementing the mitigation actions and projects identified in this Plan.

Federal regulations for mitigation plan approval require that stakeholders and the general public are given opportunities to be involved in the plan’s development and update process. Input from community members can strengthen the content and outcomes of the hazard mitigation plan. Furthermore, the plan must state continued public engagement as the Plan is carried out during its lifetime.

A public outreach strategy outlines what the community intends to achieve throughout the outreach efforts. Additionally, it identifies who to involve in the process, and how and when to effectively engage the community. Every plan participant can employ a slightly tailored engagement strategy that suits their community’s demographics, including the underserved population, and needs in addition to the lead jurisdiction’s engagement strategy.

Contra Costa County stakeholders and the public were given a number of opportunities to be involved throughout the planning process. Opportunities were provided via a public survey, in-person and virtual public meetings, and public engagement activities to review the Plan draft (i.e., public comment period).

Contra Costa County and its plan participants ensured that the stakeholder and public engagement was meaningful and productive. Additionally, the County coordinated social media, website, and news media efforts that participating jurisdictions were able to leverage within their respective outreach activities throughout the planning process. Examples of how Contra Costa County successfully used different types of outreach methods, as outlined in FEMA’s Local Mitigation Planning Handbook, are listed in Table C-1.

Table C-1. Contra Costa County Outreach Methods
Method Purpose Description
Community Events Inform
Host a booth at a fair or other event where the community will gather. Use the booth to teach residents about preparing for natural hazards. Share materials on related topics with visitors. Consider games, giveaways or other incentives as ways to engage at the event.

Interviews Consult
Host a series of structured discussions. They could be
telephone or face-to-face interviews with leaders and
representatives from each of the county’s communities, school districts, and the public. This could help to identify hazards of concern and potential mitigation measures.

News Media Inform
Work with local media outlets, including television, radio and print media partners. They can prepare stories that promote broad public involvement.

5.6.b
Packet Pg. 461 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 389
Method Purpose Description
Public Meetings Inform, Involve
Through a participating jurisdiction’s Corporate
Communications and Marketing Office, email newsletters
soliciting input on draft plan documents and public meeting attendance. Distribution lists could include government agencies, businesses, and civic organizations.

Send public meeting details to all city and county employees.

Also, post them to the community’s online public events calendar. Add them to live tickers that scroll across the bottom of the local government access television channel as well.

Share live coverage of public input meetings and let residents share their questions or comments by email.

Presentation to
Governing Bodies Inform
Share the status of the plan with the board of county
commissioners or similar governing body. These meetings should be public, and an announcement of the plan agenda item should be included in the announcement of the public meeting.

Questionnaires/
Surveys Consult
Use a survey to get information from people who could not attend the public meetings. Post the survey to your
community’s social media account(s). Ask local officials to give out copies of the survey. Have copies available for residents at municipal offices. Those offices can also post an electronic version on their websites.

Where applicable, create questionnaires/surveys in multiple languages.

Roundtables/Forums Collaborate
Sponsor a public forum to get ideas from residents on how to reduce the risk of natural hazards. This could be the main event for teaching the public. It is also a chance to let the public add to the plan’s action items. The resulting ideas may inform the jurisdiction’s planning team about risks, strengths, weaknesses and opportunities.

Social Media Inform, Involve
Make a mitigation plan Facebook page, Twitter account, or Instagram account. The page or account can include small video clips of community leaders talking about the need for mitigation planning. The page or account can also link to your questionnaire/survey.

Use the page or account to hold raffles or giveaways. This will help to support participation. For example, you may post that “All those who participate and share feedback through this page or account will be entered into a drawing.”
Area-Specific
Meetings Involve
Host small, area-specific meetings twice each year. You can hold them at public libraries and other public venues. These meetings give you a chance to share reading materials. They can educate residents on actions they can take to mitigate natural hazards, save lives and prevent property damage.

These meetings can also gather input on making the
mitigation process more effective.

5.6.b
Packet Pg. 462 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 390
Method Purpose Description
Website Involve, Consult
You can use a website to promote the mitigation plan by sharing:

What hazard mitigation planning is.

A list of who is involved in the local planning process.

How the plan update process works.

Information about future stakeholder meetings and
chances for public involvement.

You can share contact information for questions or comments.

Downloads available from the site could include copies of the existing
Outreach Purpose Definitions:

Inform: To provide the public with balanced and objective information to assist them in understanding the problem, alternatives, opportunities and/or solutions.

Consult: To obtain public feedback on analysis, alternatives and/or decisions.

Involve: To work directly with the public throughout the process to ensure that public concerns and aspirations are consistently understood and considered.

Collaborate: To partner with the public in each aspect of the decision, including the development of alternatives and the identification of the preferred solution.

Empower: To place final decision making in the hands of the public.

Public engagement participation and supporting documentation for each plan participant can be found in their respective annexes.

How Public Input was Incorporated into the Plan
Information and feedback gained through the public survey, public meetings, and public comment period provided valuable data to validate and confirm the risk assessment findings and potential mitigation strategies. Specifically, feedback from the public offered during the public meetings offered greater insights into the public’s concerns regarding specific hazards and their impacts. The public also offered specific initiatives they felt would create greater resiliency for the County and its residents.

Survey results helped validate the hazards included in the Plan, the hazard ranking process, and areas where the County and jurisdictions could further improve outreach and education efforts. Open-ended responses, specifically regarding their experience with damages from past hazards, helped to validate hazard-specific impact data in Chapter 4 (Hazard Identification and Risk Assessment). These, and related findings, helped the Core Planning Team and local planning teams determine meaningful mitigation projects.

5.6.b
Packet Pg. 463 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 391
C.1. PUBLIC MEETINGS
Contra Costa County OES hosted three (3) public meetings throughout the County on December 4, 2023, December 5, 2023, and December 6, 2023. Two (2) public meetings were conducted in hybrid format with the public having the option to attend in person or virtually (i.e., Zoom, live stream). These meetings allowed the County to introduce the Plan update, identify additional hazards of concern that should be included, if any, and to provide input for the various mitigation measures intended to eliminate or reduce the negative impact to those hazards. Language translation assistance in Spanish was available in all public meetings.

During the Public Meetings, forms were provided to each participant to identify and describe how the identified hazards for Contra Costa County have impacted (or could impact) their place of residence and/or work, municipality, or organization. Additionally, participants were asked to provide mitigation actions/ideas and to identify additional hazards of concern. Although highly encouraged, these forms were voluntary and confidential.

Public Meeting Calendar
December 2023
Date Monday, December 4th Tuesday, December 5th
Event Name Public Meeting #1 Public Meeting #2
Location Contra Costa County Auditorium
1850 Muir Road, Martinez, CA 94553
San Pablo Community Center
2450 Road 20, San Pablo, CA 94806
Outreach Method Public Meetings, Roundtable/Forums Public Meetings, Roundtable/Forums Outreach Purpose Inform, Involve, Collaborate Inform, Involve, Collaborate Targeted Population
Countywide (Access and Functional
Needs, Age, Ethnicity, High Poverty,
Limited Access to a Vehicle, Limited
English Proficiency)
Countywide (Access and Functional
Needs, Age, Ethnicity, High Poverty,
Limited Access to a Vehicle, Limited
English Proficiency)
Accommodations Provided After Hours, Spanish Speaking Available, Virtual Options
After Hours, Spanish Speaking Available,
Virtual Options
Date Wednesday, December 6th
Event Name Public Meeting #3
Location Oakley City Council Chambers
3231 Main Street Oakley, CA 94561
Outreach Method Public Meetings, Roundtable/Forums
Outreach Purpose Inform, Involve, Collaborate
Targeted Population Countywide (Access and Functional Needs, Age, Ethnicity, High Poverty, Limited Access to a Vehicle, Limited English Proficiency)
Accommodations Provided After Hours, Spanish Speaking Available The public meeting forms samples, agendas, sign in sheets are below.

5.6.b
Packet Pg. 464 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 392
Hazard Assessment Form

5.6.b
Packet Pg. 465 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 393
New Mitigation Action Forms

5.6.b
Packet Pg. 466 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 394
December 4, 2023 – Public Meeting #1

5.6.b
Packet Pg. 467 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 395

5.6.b
Packet Pg. 468 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 396

5.6.b
Packet Pg. 469 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 397
December 5, 2023 – Public Meeting #2

5.6.b
Packet Pg. 470 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 398

5.6.b
Packet Pg. 471 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 399
December 6, 2023 – Public Meeting

5.6.b
Packet Pg. 472 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 400

5.6.b
Packet Pg. 473 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 401
Figure C-1 Social Media Posts Samples

5.6.b
Packet Pg. 474 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 402

5.6.b
Packet Pg. 475 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 403

5.6.b
Packet Pg. 476 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 404
Figure C-2 Contra Costa County Website

5.6.b
Packet Pg. 477 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 405
C.2. PUBLIC SURVEY
The 2024 Contra Costa County Hazard Mitigation Questionnaire (i.e., Public Survey) was available in English, Spanish, Traditional Chinese, Simplified Chinese, and Tagalog. The English and Spanish survey opened on October 19, 2023. While the Traditional Chinese, Simplified Chinese, and Tagalog open on November 15, 2023. The Survey was distributed and promoted through a variety of methods such as social media (e.g., Facebook, Instagram, Twitter), press releases to the County and 19 city Public Information Officers (PIOs), County Board of Supervisors, and the Bay Area media outlets (e.g., Kron4 and NBC Bay Area). Community organizations and plan participants were critical in connecting county and city residents with the Survey, and Contra Costa County OES used their broad-based distribution lists of community stakeholders to disseminate the Survey to residents and employees. Ultimately, respondents for this Survey were selected from among those who volunteered to participate. No special weighting was done to reflect the demographic composition of the County.

As part of this Survey, Steering Committee members, community representatives, and members of the public were asked to rate each of the hazards in terms of perceived risk. Furthermore, they were asked to rate “mitigation importance” for each of the identified hazards in the Plan. The information gathered from this survey was used to inform the hazard risk prioritization process, and to ensure the Plan adequately addressed the public’s’ concerns and priorities.

The Survey had a total of 32 questions of multiple choice and open-ended questions. In total 1,895 respondents participated in the five (5) surveys. To ensure all data could be accurately correlated, only the completed (in its entirety) survey was used in this report. In some situations, the respondent chose not to answer one (1) or more questions which is why some discrepancies exist in the total number of responses per question. Table C-1 provides a breakdown of the Survey responses for each language.

Table C-2. Survey Response Summary
Survey Status
Total
English Spanish Tagalog Traditional
Chinese
Simplified
Chinese
Completed 1,365 18 2 1 1
Partial 476 21 0 1 0
Disqualified* 9 0 0 0 0
TOTAL 1,850 39 2 2 1
*A survey response is Disqualified when the respondent selects “No, I do not live or work in Contra Costa County.” for question 1.

5.6.b
Packet Pg. 478 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 406
Figure C-3 Social Media and Website Posts Samples

5.6.b
Packet Pg. 479 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 407

5.6.b
Packet Pg. 480 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 408

5.6.b
Packet Pg. 481 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 409

5.6.b
Packet Pg. 482 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 410

5.6.b
Packet Pg. 483 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 411

5.6.b
Packet Pg. 484 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 412

5.6.b
Packet Pg. 485 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 413
Survey Results
NOTE: This is the redacted version of the Survey. Open-ended responses from the public were NOT included in this version to ensure confidentiality and privacy.

Question 1: Do you live and/or work in Contra Costa County? Please select the best answer that applies to your current situation.

Value Percent Total Responses
Yes, I live in Contra Costa County. 61.8% 1,091
Yes, I live and work in Contra Costa County. 31.3% 553
Yes, I live in Contra Costa County, but work in another county. 3.6% 64
Yes, I work in Contra Costa County, but live in another county. 2.5% 45
No, I do not live or work in Contra Costa County. 0.4% 7 I do not know 0.3% 6
TOTAL 1,766
Yes, I live in Contra
Costa County.
62%
Yes, I live and work
in Contra Costa
County.
31%
Yes, I live in Contra
Costa County, but
work in another
county.
4%
Yes, I work in
Contra Costa
County, but live in
another county.
3%
No, I do not live or
work in Contra Costa
County.
0%
I do not know.
0%

5.6.b
Packet Pg. 486 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 414
Spanish Survey Results
Value Percent Total Responses
Yes, I live in Contra Costa County. 54.5% 18
Yes, I live and work in Contra Costa County. 36.4% 12
Yes, I live in Contra Costa County, but work in another county. 6.1% 2
Yes, I work in Contra Costa County, but live in another county. 3.0% 1
No, I do not live or work in Contra Costa County. 54.5% 18 I do not know 36.4% 12
TOTAL 33

5.6.b
Packet Pg. 487 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 415
Question 2: Approximately how many years have you lived in Contra Costa County? Value Percent Total Responses
0-2 years 4.1% 68
3-5 years 7.4% 124
6-10 years 9.6% 161
11-20 years 14.2% 239
21 or more years 64.2% 1,078
Not Applicable 0.4% 6
I do not know 0.2% 3
TOTAL 166
0-2 years
4%
3-5 years
7%
6-10 years
10%
11-20 years
14%
21 or more years
64%
Not Applicable
1%
I Do Not Know
0%

5.6.b
Packet Pg. 488 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 416
Spanish Survey Results
Value Percent Total Responses
0-2 years 10.7% 3
3-5 years 7.1% 2
6-10 years 17.9% 5
11-20 years 17.9% 5
21 or more years 46.4% 13 TOTAL 28

5.6.b
Packet Pg. 489 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 417
Question 3: Approximately how many years have you worked in Contra Costa County? Value Percent Total Responses
0-2 years 7.5% 44
3-5 years 14.1% 83
6-10 years 16.6% 98
11-20 years 20.9% 123
21 or more years 40.6% 239
Not Applicable 0.3% 2
I do not know 7.5% 44
TOTAL 589
0-2 years
7%
3-5 years
14%
6-10 years
17%
11-20 years
21%
21 or more years
41%
Not Applicable
0%

5.6.b
Packet Pg. 490 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 418
Spanish Survey Results
Value Percent Total Responses
0-2 years 18.2% 2
3-5 years 27.3% 3
6-10 years 9.1% 1
11-20 years 27.3% 3
21 or more years 18.2% 2 TOTAL 11

5.6.b
Packet Pg. 491 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 419
Question 4: Please indicate which community in Contra Costa County you live in.

Community Percent Total Responses
Acalanes Ridge 0.1% 1
Alamo 1.5% 23
Alhambra Valley 0.1% 2
Antioch 5.2% 80
Bay Point 0.9% 14
Bayview 0.1% 1
Bethel Island/Sandmound Slough 5.0% 76
Blackhawk 0.4% 6
Brentwood 3.7% 57
Briones 0.1% 1
Byron 0.4% 6
Camino Tassajara 0.1% 2
Castle Hill 0.2% 3
Clayton 1.0% 16
Clyde 0.1% 1
Concord 8.0% 123
Contra Costa Centre 0.5% 7
Crockett 0.4% 6
Town of Danville 3.7% 57
Diablo 0.1% 1
Discovery Bay 1.3% 20
East Richmond Heights 0.6% 9
El Cerrito 2.5% 38
El Sobrante 3.5% 54
Hercules 1.6% 24
Kensington 0.9% 14
Knightsen 0.1% 1
Lafayette 2.7% 41
Martinez 14.4% 220
Town of Moraga 2.9% 45
Mountain View 0.2% 3
North Richmond 0.1% 1

5.6.b
Packet Pg. 492 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 420
Community Percent Total Responses
Oakley 4.4% 67
Orinda 3.5% 54
Pacheco 0.3% 5
Pinole 2.0% 31
Pittsburg 2.7% 41
Pleasant Hill 2.7% 42
Richmond 5.9% 90
Rodeo 0.8% 12
Rollingwood 0.1% 2
San Pablo 0.9% 14
San Ramon 3.1% 47
Saranap/Parkmead 0.1% 2
Tara Hills 0.1% 2
Vine Hill 0.1% 1
Walnut Creek 10.8% 165 TOTAL 1,528
Spanish Survey Results
Community Percent Total Responses
Antioch 13.8% 4
Brentwood 10.3% 3
Concord 6.9% 2
Hercules 6.9% 2
Martinez 10.3% 3
Oakley 3.4% 1
Richmond 34.5% 10
San Pablo 6.9% 2
San Ramon 6.9% 2 TOTAL 29

5.6.b
Packet Pg. 493 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 421
Question 5: Please indicate which community in Contra Costa County you work in.

Community Percent Total Responses
Alamo 0.7% 4
Antioch 8.9% 51
Bay Point 0.3% 2
Bethel Island/Sandmound Slough 1.2% 7
Blackhawk 0.3% 2
Brentwood 3.5% 20
Castle Hill 0.2% 1
Clayton 0.5% 3
Concord 11.3% 65
Contra Costa Centre 0.5% 3
Crockett 0.3% 2
Town of Danville 1.7% 10
Discovery Bay 0.3% 2
El Cerrito 1.4% 8
El Sobrante 0.9% 5
Hercules 1.4% 8
Kensington 0.3% 2
Lafayette 1.6% 9
Martinez 23.7% 136
Town of Moraga 3.0% 17
Mountain View 0.3% 2
North Richmond 0.2% 1
Oakley 3.7% 21
Orinda 1.6% 9
Pacheco 0.5% 3
Pinole 1.7% 10
Pittsburg 1.2% 7
Pleasant Hill 8.0% 46
Richmond 7.1% 41
Rodeo 0.3% 2
Rollingwood 0.2% 1

5.6.b
Packet Pg. 494 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 422
Community Percent Total Responses
San Pablo 0.5% 3
San Ramon 1.9% 11
Walnut Creek 10.5% 60 TOTAL 574
Spanish Survey Results
Community Percent Total Responses
Brentwood 18.2% 2
Hercules 9.1% 1
Martinez 18.2% 2
Pittsburg 9.1% 1
Pleasant Hill 9.1% 1
Richmond 27.3% 3
San Ramon 9.1% 1 TOTAL 11

5.6.b
Packet Pg. 495 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 423
Question 6: Please indicate what type of device(s) you use to access the internet. Select ALL that apply.

Value Percent Total Responses
Computer/laptop at home 89.7% 1,357
Computer/laptop at work/office 41.3% 625
iPad/tablet 51.6% 781
Cellphone 93.8% 1,419
Public computer (e.g., library) 3.5% 53
I do not have access to the Internet 0.2% 3
I do not know 0.2% 3
Other 1.1% 17

89.7%

41.3%

51.6%

93.8%

3.5%

0.2% 0.2% 1.1%
0 10
20 30
40 50
60 70
80 90
100

5.6.b
Packet Pg. 496 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 424
Spanish Survey Results
Value Percent Total Responses
Computer/laptop at home 75.0% 18
Computer/laptop at work/office 50.0% 12
iPad/tablet 45.8% 11
Cellphone 95.8% 23
Public computer (e.g., library)0.0% 0
I do not have access to the Internet0.0% 0
I do not know0.0% 0
Other4.2% 1

5.6.b
Packet Pg. 497 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 425
Question 7: Please indicate those activities you have done to prepare for emergencies and disasters. Please select ALL that apply. I have…
Value Percent Total Responses
an emergency preparedness plan. 39.7% 600
flood Insurance. 9.6% 145
a 72 hour kit/disaster supply kit. 53.4% 807
visited local government website(s) for emergency
preparedness information. 39.6% 598
an evacuation plan. 31.1% 469
a weather radio. 33.4% 505
signed up for emergency alerts for your local
emergency management office (e.g., Harris County). 72.4% 1,093 not taken any preparedness actions. 12.5% 189
Other 8.9% 135

39.7%

9.6%

53.4%

39.6%

31.1%

33.4%

72.4%

12.5%

8.9%
0 10
20 30
40 50
60 70
80 5.6.b
Packet Pg. 498 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 426
Spanish Survey Results
Value Percent Total Responses
an emergency preparedness plan. 29.2% 7
flood Insurance. 4.2% 1
a 72 hour kit/disaster supply kit. 45.8% 11
visited local government website(s) for emergency
preparedness information. 25.0% 6
an evacuation plan. 37.5% 9
a weather radio. 0.0% 0
signed up for emergency alerts for your local
emergency management office (e.g., Harris County). 50.0% 12 not taken any preparedness actions. 25.0% 6
Other 12.5% 3

5.6.b
Packet Pg. 499 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 427
Question 8: Have any of the reasons below prevented you from pursuing additional preparedness activities? Please select ALL that apply.

Value Percent Total Responses
I do not think it will make a difference. 6.9% 100
I do not know what to do. 21.7% 316
I do not have the time. 15.7% 229
It costs too much. 17.3% 252
I do not need to prepare because emergency
responders (e.g., fire, police, etc.) will help me during an emergency.

2.3% 33
None of the above apply to me. 43.6% 634
Other 13.5% 196

6.9%

21.7%

15.7%

17.3%

2.3%

43.6%

13.5%
0 5
10 15
20 25
30 35
40 45
50 I do not think
it will make a
difference.

I do not
know what to
do.

I do not have
the time.

It costs too
much.

I do not need
to prepare
because
emergency
responders
(e.g., fire,
police, etc.)
None of the
above apply
to me.

Other
(please
describe)

5.6.b
Packet Pg. 500 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 428
Spanish Survey Results
Value Percent Total Responses
I do not think it will make a difference. 0.0% 0
I do not know what to do. 34.8% 8
I do not have the time. 34.8% 8
It costs too much. 21.7% 5
I do not need to prepare because emergency
responders (e.g., fire, police, etc.) will help me during an emergency.

4.3% 1
None of the above apply to me. 13.0% 3
Other 8.7% 2

5.6.b
Packet Pg. 501 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 429
Question 9: Please indicate where you go to obtain emergency and disaster preparedness related information? Please select ALL that apply.

Value Percent Total Responses
Municipal (i.e., city, town) government websites 43.6% 657 County government websites 50.5% 761
State government websites 39.0% 587
Federal government websites (e.g., fema.gov,
Ready.gov) 39.6% 596
Web search (e.g., bing.com, google.com) 54.8% 826
Social media (e.g., Facebook, X (formerly known as
Twitter), etc.) 25.6% 385
Voluntary organizations (e.g., American Red Cross,
Salvation Army, etc.) 23.5% 354
Religious organization 4.0% 60

43.6%

50.5%
39%

39.6%

54.8%

25.6%

23.5%
4%

25.9%

14.1%

0.5%0.6%

24.1%

17.1%

0.3%

18.4%

30.7%

9.1%

4.4%

1.6%
0 10
20 30
40 50
60 5.6.b
Packet Pg. 502 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 430
Value Percent Total Responses
Local English-speaking television 25.9% 390
Local English-speaking radio 14.1% 212
Local Spanish-speaking television 0.5% 8
Local Spanish-speaking radio 0.6% 9
National News (Radio and Television) 24.1% 363
Print Media in English (e.g., newspapers) 17.1% 257
Print Media in Spanish (e.g., newspapers) 0.3% 5
Brochures and Newsletters 18.4% 277
Word of Mouth (e.g., friends, family, co-workers) 30.7% 462 Other (please specify) 9.1% 137
I do not know 4.4% 67
Spanish Survey Results
Value Percent Total Responses
Municipal (i.e., city, town) government websites 37.5% 9 County government websites 41.7% 10
State government websites 25.0% 6
Federal government websites (e.g., fema.gov,
Ready.gov) 25.0% 6
Web search (e.g., bing.com, google.com) 45.8% 11
Social media (e.g., Facebook, X (formerly known as
Twitter), etc.) 29.2% 7
Contra Costa County Community Warning System 37.5% 9
Voluntary organizations (e.g., American Red Cross,
Salvation Army, etc.) 25.0% 6
Religious organization 4.2% 1
Local English-speaking television 33.3% 8
Local English-speaking radio 16.7% 4
Local Spanish-speaking television 29.2% 7
Local Spanish-speaking radio 20.8% 5
National News (Radio and Television) 33.3% 8
Print Media (e.g., newspapers) 16.7% 4
Word of Mouth (e.g., friends, family, co-workers) 33.3% 8 Other (please specify) 8.3% 2
I do not know 4.2% 1

5.6.b
Packet Pg. 503 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 431
Question 10: Please indicate how you expect to receive alerts and information during an emergency. Please select ALL that apply.

Value Percent Total Responses
A weather radio 28.7% 432
Private weather applications (e.g., Weather Channel,
Wunderground, Weather Bug, AccuWeather, etc.) 34.7% 521 Preparedness applications (e.g., FEMA, Red Cross,
etc.) 27.8% 418
Local media news applications 54.0% 812
Contra Costa County Community Warning System 80.4% 1,208 Contra Costa County Sheriff's Office of Emergency
Services website 32.4% 487
Local media (e.g., television broadcast and/or
smartphone application) 59.3% 891
Radio 48.0% 721

28.7%

34.7%

27.8%
54%

80.4%

32.4%

59.3%
48%

38.5% 39.3%
35%

3.7%
7%
0 10
20 30
40 50
60 70
80 90
A weather radio Private weather
applications (e.g.,
Weather Channel,
Wunderground,
Weather Bug,
Preparedness
applications (e.g.,
FEMA, Red
Cross, etc.)
Local media news
applications
Contra Costa
County
Community
Warning System
Contra Costa
County Sheriff's
Office of
Emergency
Services website
Local media (e.g.,
television
broadcast and/or
smartphone
application)
Radio Social media Outdoor warning
sirens
Word of mouth
(e.g., friends,
family, coworkers)
I do not know Other (please
describe)

5.6.b
Packet Pg. 504 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 432
Value Percent Total Responses
Social media 38.5% 579
Outdoor warning sirens 39.3% 590
Word of mouth (e.g., friends, family, co-workers) 35.0% 526 I do not know 3.7% 56
Other 7.0% 105
Spanish Survey Results
Value Percent Total Responses
A weather radio 12.5% 3
Private weather applications (e.g., Weather Channel,
Wunderground, Weather Bug, AccuWeather, etc.) 54.2% 13
Preparedness applications (e.g., FEMA, Red Cross,
etc.) 29.2% 7
Local media news applications 45.8% 11
Contra Costa County Community Warning System 62.5% 15
Contra Costa County Sheriff's Office of Emergency
Services website 45.8% 11
Local media (e.g., television broadcast and/or
smartphone application) 41.7% 10
Radio 37.5% 9
Social media 45.8% 11
Outdoor warning sirens 37.5% 9
Word of mouth (e.g., friends, family, co-workers) 41.7% 10 Other 4.2% 1

5.6.b
Packet Pg. 505 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Spanish Survey Results

5.6.b
Packet Pg. 506 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 434
Question 13: If a disaster (i.e., earthquake, wildfire) impacted Contra Costa County, knocking out electricity and running water, would your household be able to manage on its own for at least three (3) days?
Value Percent Total Responses
Yes 56.3% 848
Maybe 31.1% 469
No 9.7% 146
I do not know 2.9% 43
Total 1,506

2.9%

9.7%

31.1%

56.3%
0 10 20 30 40 50 60
I do not know
No
Maybe
Yes
Percent

5.6.b
Packet Pg. 507 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 435
Spanish Survey Results
Value Percent Total Responses
Yes 33.3% 8
Maybe 16.7% 4
No 41.7% 10
I do not know 8.3% 2
Total 24

5.6.b
Packet Pg. 508 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 436
Question 14: Do you believe that Contra Costa County might ever be threatened by the following hazards? Please rate what hazards present the greatest risk.

Low Risk: Low impact on threat to life and property damage.

Medium Risk: Medium impact on threat to life and property damage.

High Risk: High impact on threat to life and property damage.

Value
Low Risk Medium Risk High Risk Not Applicable Total
Responses Count % Count % Count % Count %
Climate Change 369 27.2% 490 36.1% 466 34.3% 34 2.5% 1,359 Dam and Levee Failure 834 61.9% 190 14.1% 154 11.4% 169 12.5% 1,347 Drought 246 18.0% 470 34.4% 637 46.6% 14 1.0% 1,367
Earthquake 43 3.1% 373 26.9% 965 69.7% 4 0.3% 1,385
Flood 710 52.1% 401 29.4% 205 15.0% 48 3.5% 1,364
Landslide 747 55.4% 376 27.9% 157 11.6% 68 5.0% 1,348
Severe Thunderstorm 521 38.2% 573 42.0% 256 18.8% 13 1.0% 1,363 Strong Winds (greater
than 58 mph) 244 17.8% 639 46.7% 478 34.9% 7 0.5% 1,368 Hail 800 58.9% 441 32.5% 101 7.4% 16 1.2% 1,358
Tsunami 977 72.6% 132 9.8% 63 4.7% 173 12.9% 1,345
Wildfire 236 17.2% 410 29.9% 712 51.9% 14 1.0% 1,372
Sea Level Rise 785 58.1% 300 22.2% 138 10.2% 128 9.5% 1,351

5.6.b
Packet Pg. 509 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 437
Spanish Survey Results
Value
Low Risk Medium Risk High Risk Not Applicable Total
Responses Count % Count % Count % Count %
Climate Change 4 21.1% 7 36.8% 7 36.8% 1 5.3% 19
Dam and Levee Failure 8 44.4% 6 33.3% 3 16.7% 1 5.6% 18 Drought 6 31.6% 5 26.3% 6 31.6% 2 10.5% 19
Earthquake 2 10.5% 7 36.8% 9 47.4% 1 5.3% 19
Flood 5 26.3% 9 47.4% 4 21.1% 1 5.3% 19
Landslide 7 38.9% 3 16.7% 5 27.8% 3 16.7% 18
Severe Thunderstorm 5 27.8% 9 50.0% 1 5.6% 3 16.7% 18
Strong Winds (greater
than 58 mph) 4 21.1% 8 42.1% 6 31.6% 1 5.3% 19
Hail 7 36.8% 7 36.8% 3 15.8% 2 10.5% 19
Tsunami 11 57.9% 6 31.6% 0 % 2 10.5% 19
Wildfire 2 10.5% 5 26.3% 9 47.4% 3 15.8% 19
Sea Level Rise 6 31.6% 6 31.6% 6 31.6% 1 5.3% 19

5.6.b
Packet Pg. 510 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 438
Question 15: Please select the answer that best describes your experience.

Value Percent Total Responses
I have never experienced loss from a disaster(s). 47.5% 659 I have experienced minor loss from a disaster(s). 45.6% 633 I have experienced major loss from a disaster(s). 6.0% 83 I have experienced catastrophic loss from a
disaster(s). 0.9% 13
Total 1,388

47.5%

45.6%
6%

0.9%
0 5
10 15
20 25
30 35
40 45
50 I have never
experienced property
damage or loss from a
disaster(s).

I have experienced
minor property
damage and loss from
a disaster(s).

I have experienced
major property damage
and loss from a
disaster(s).

I have experienced
catastrophic property
damage and loss from
a disaster(s).

5.6.b
Packet Pg. 511 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 439
Spanish Survey Results
Value Percent Total Responses
I have never experienced loss from a disaster(s). 52.6% 10 I have experienced minor loss from a disaster(s). 36.8% 7 I have experienced major loss from a disaster(s). 10.5% 2 I have experienced catastrophic loss from a
disaster(s). 0.0% 0
Total 19
Question 16: If you have experienced any damage(s) or injury(ies) from a disaster, please list the hazard(s) that caused the damages/losses and/or injuries (e.g., flooding, wind, wildfire).

REDACTED
Question 17: If you have experienced any damage(s) or injury(ies) from a disaster, please indicate where this occurred (e.g., my home, on a roadway or intersection, at work, on vacation, etc.). REDACTED

5.6.b
Packet Pg. 512 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 440
Question 18: If you have experienced any damage(s) or injury(ies) from a disaster, please describe the damages and/or injuries. (e.g., house flooded, roof was damaged, vehicle was damaged, broken bones, lacerations, etc.). REDACTED
Question 19: Based on YOUR PERCEPTION of your jurisdiction's hazards, to what degree of emphasis would you expect your jurisdiction to mitigate the following hazards? Definition: Hazard mitigation is any sustainable action that reduces or eliminates long-term risk to people and property from future disasters. Hazard mitigation includes long-term solutions that reduce the impact of disasters in the future.

No Mitigation Needed: No mitigation on this hazard is expected or needed.

Low Priority: This hazard should be mitigated, but is not a high priority compared to other hazards.

Medium Priority: It is important to mitigate this hazard.

High Priority: It is a high priority to emphasize mitigation for this hazard.

Value
No Mitigation
Needed Low Priority Medium Priority High Priority Total Responses
Count % Count % Count % Count %
Climate Change 194 14.4% 274 20.3% 373 27.6% 509 37.7% 1,350 Dam and Levee Failure 369 27.2% 415 30.6% 290 21.4% 282 20.8% 1,356 Drought 80 5.9% 250 18.4% 470 34.6% 558 41.1% 1,358
Earthquake 28 2.0% 96 7.0% 385 28.0% 865 63.0% 1,374
Flood 157 11.6% 389 28.7% 478 35.3% 331 24.4% 1,355
Landslide 223 16.5% 464 34.4% 431 31.9% 232 17.2% 1,350 Severe Thunderstorm 247 18.2% 577 42.6% 361 26.6% 170 12.5% 1,355 Strong Winds (greater
than 58 mph) 108 8.0% 379 27.9% 547 40.3% 322 23.7% 1,356 Hail 449 33.4% 679 50.6% 160 11.9% 55 4.1% 1,343
Tsunami 630 46.8% 486 36.1% 142 10.5% 88 6.5% 1,346
Wildfire 47 3.5% 137 10.1% 281 20.6% 896 65.8% 1,361
Sea Level Rise 410 30.5% 427 31.7% 315 23.4% 193 14.3% 1,345

5.6.b
Packet Pg. 513 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 441
Spanish Survey Results
Value
No Mitigation
Needed Low Priority Medium Priority High Priority Total Responses
Count % Count % Count % Count %
Climate Change 0 % 4 21.1% 7 36.8% 8 42.1% 19
Dam and Levee Failure 2 11.1% 5 27.8% 6 33.3% 5 27.8% 18 Drought 2 10.5% 2 10.5% 9 47.4% 6 31.6% 19
Earthquake 1 5.3% 0 % 9 47.4% 9 47.4% 19
Flood 0 % 4 21.1% 9 47.4% 6 31.6% 19
Landslide 2 11.1% 4 22.2% 7 38.9% 5 27.8% 18
Severe Thunderstorm 2 10.5% 6 31.6% 8 42.1% 3 15.8% 19
Strong Winds (greater
than 58 mph) 0 % 8 42.1% 7 36.8% 4 21.1% 19
Hail 5 26.3% 6 31.6% 7 36.8% 1 5.3% 19
Tsunami 3 15.8% 6 31.6% 7 36.8% 3 15.8% 19
Wildfire 0 % 2 10.5% 8 42.1% 9 47.4% 19
Sea Level Rise 1 5.3% 3 15.8% 10 52.6% 5 26.3% 19

5.6.b
Packet Pg. 514 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion)

5.6.b
Packet Pg. 515 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) Spanish Survey Results

5.6.b
Packet Pg. 516 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 444
Question 22: What might prevent you from leaving your place of residence if there was an evacuation order? Please select ALL that apply.

Value Percent Total Responses
Pet(s) 28.8% 387
Job 5.4% 72
Need to care for another person 13.8% 185
Spouse/Significant Other will not leave 9.1% 122
Need to stay and protect property 21.2% 285
Lack of money 9.3% 125
No place to go 21.5% 289
No transportation 4.5% 61
Traffic 34.3% 462

28.8%

5.4%

13.8%

9.1%

21.2%

9.3%

21.5%

4.5%

34.3%

10.8% 10.7%

24.9%

7.7%

33.7%

0.5%
0 5
10 15
20 25
30 35
40 5.6.b
Packet Pg. 517 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 445
Value Percent Total Responses
Lack of gas/fuel for vehicle 10.8% 145
Disability/Health Issues 10.7% 144
Concerned for safety if I leave 24.9% 335
Other (please specify) 7.7% 103
No obstacles would prevent me from evacuating 33.7% 453 I would refuse to evacuate, no matter what 0.5% 7 Spanish Survey Results
Value Percent Total Responses
Pet(s) 52.9% 9
Job 29.4% 5
Need to care for another person 23.5% 4
Spouse/Significant Other will not leave 17.6% 3
Need to stay and protect property 35.3% 6
Lack of money 11.8% 2
No place to go 23.5% 4
No transportation 0.0% 0
Traffic 41.2% 7
Lack of gas/fuel for vehicle 5.9% 1
Disability/Health Issues 5.9% 1
Concerned for safety if I leave 5.9% 1
Other (please specify) 5.9% 1
No obstacles would prevent me from evacuating 23.5% 4
I would refuse to evacuate, no matter what 0.0% 0

5.6.b
Packet Pg. 518 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 446
Question 23: If you were to evacuate, where would you most likely stay? Please select the best answer.

Value Percent Total Responses
Shelter/evacuation center 8.8% 120
Church or place of worship 1.8% 24
Workplace 1.3% 18
Home of a friend or relative 48.4% 662
Hotel/motel 19.2% 262
I have no place to go 4.3% 59
I do not know 10.5% 143
Other (please specify) 5.8% 80
Total 1,368

8.8%

1.8% 1.3%

48.4%

19.2%

4.3%

10.5%

5.8%
0 10
20 30
40 50
60 5.6.b
Packet Pg. 519 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 447
Spanish Survey Results
Value Percent Total Responses
Shelter/evacuation center 11.1% 2
Church or place of worship 0.0% 0
Workplace 0.0% 0
Home of a friend or relative 61.1% 11
Hotel/motel 5.6% 1
I have no place to go 5.6% 1
I do not know 16.7% 3
Other (please specify) 0.0% 0
Total 18

5.6.b
Packet Pg. 520 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 448
Question 24: In an evacuation, would you or anyone in your household require special assistance?
Value Percent Total Responses
Yes 9.6% 132
Maybe 69.4% 950
No 16.1% 221
I do not know 2.9% 40
Other 1.9% 26
Total 1,369

9.6%

69.4%

16.1%

2.9% 1.9%
0 10
20 30
40 50
60 70
80 Yes No Maybe I do not know Other (please
specify)

5.6.b
Packet Pg. 521 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 449
Spanish Survey Results
Value Percent Total Responses
Yes 5.6% 1
Maybe 11.1% 2
No 66.7% 12
I do not know 16.7% 3
Other 0.0% 0
Total 18

5.6.b
Packet Pg. 522 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 450
Question 25: If yes, who would provide assistance?
Value Percent Total Responses
Within household 44.3% 153
Friend/relative (outside household) 15.7% 54
Outside Agency 1.7% 6
I do not know 34.2% 118
Not applicable 0.9% 3
Other 3.2% 11
Total 345

44.3%

15.7%

1.7%

34.2%

0.9%

3.2%
0 5
10 15
20 25
30 35
40 45
50 Within
household
Friend/relative
(outside
household)
Outside
Agency
I do not know Not applicable Other (please
specify)

5.6.b
Packet Pg. 523 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 451
Spanish Survey Results
Value Percent Total Responses
Within household 0.0% 0
Friend/relative (outside household) 0.0% 0
Outside Agency 33.3% 1
I do not know 66.7% 2
Not applicable 0.0% 0
Other 0.0% 0
Total 3
Question 26: If applicable, please indicate what kind of outside assistance your household may need during an evacuation (e.g., transportation, medical, etc.). REDACTED

5.6.b
Packet Pg. 524 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 452
Question 27: Which best describes your living arrangement?

82.2%

4.5%

8.6%

1.4% 1% 0.7% 0.2% 0.2% 0.1% 1.1%
0 10
20 30
40 50
60 70
80 90
Value Percent Total Responses
Attached/Detached single family home 82.2% 1,119
Duplex, triplex, fourplex, six-plex home 4.5% 61
Multi-family building – 2 stories or more
(apartment/condominium) 8.6% 117
Mobile home 1.4% 19
Manufactured home 1.0% 13
Recreational vehicle (RV) 0.7% 10
Some other type of structure 0.2% 3
I do not know 0.2% 3
Place not meant for habitation (e.g., a vehicle, an
abandoned building, bus/train/subway station/airport
or anywhere outside)

0.1% 1

5.6.b
Packet Pg. 525 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 453
Spanish Survey Results
Value Percent Total Responses
Attached/Detached single family home 66.7% 12
Duplex, triplex, fourplex, six-plex home 0.0% 0
Multi-family building – 2 stories or more
(apartment/condominium) 16.7% 3
Mobile home 0.0% 0
Manufactured home 0.0% 0
Recreational vehicle (RV) 0.0% 0
Some other type of structure 0.0% 0
I do not know 16.7% 3
Place not meant for habitation (e.g., a vehicle, an
abandoned building, bus/train/subway station/airport
or anywhere outside)

0.0% 0
Other 0.0% 0
Total 18
Value Percent Total Responses
Other 1.1% 15
Total 1,361

5.6.b
Packet Pg. 526 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 454
Question 28: Which of the following best describes your race/ethnicity? Please select ALL that apply.

Value Percent Total Responses
American Indian or Alaska Native 2.5% 33
Asian or Asian American 8.3% 111
Black or African American 4.2% 56
Hawaiian or Other Pacific Islander 1.4% 18
Hispanic or Latino 8.6% 114
Non-Hispanic White 69.6% 928
Two or more races 8.9% 119
Other 7.6% 101

2.5%

8.3%

4.2%

1.4%

8.6%

69.6%

8.9% 7.6%
0 10
20 30
40 50
60 70
80 5.6.b
Packet Pg. 527 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 455
Spanish Survey Results
Value Percent Total Responses
American Indian or Alaska Native 5.9% 1
Asian or Asian American 0.0% 0
Black or African American 0.0% 0
Hawaiian or Other Pacific Islander 0.0% 0
Hispanic or Latino 76.5% 13
Non-Hispanic White 17.6% 3
Two or more races 0.0% 0
Other 5.9% 1

5.6.b
Packet Pg. 528 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 456
Question 29: Please indicate the language(s) spoken in your household. Please select ALL that apply.

Value Percent Total Responses
English 99.5% 1,347
Spanish 5.6% 76
Mandarin 1.0% 13
Tagalog 1.3% 18
Other 4.7% 63
Other languages spoken: Cantonese, German, Hindi, Italian, Portuguese, Farsi, French, German, Korean, American Sign Language (ALS), Arabic, Armenian, Braille, Burmese, Gujarati

99.5 5.6%
1% 1.3%

4.7%
0 20
40 60
80 100
120
English Spanish Mandarin Tagalog Other (please
specify)

5.6.b
Packet Pg. 529 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 457
Spanish Survey Results
Value Percent Total Responses
English 88.2% 15
Spanish 76.5% 13
Mandarin 0.0% 0
Tagalog 0.0% 0
Other 5.9% 1
Other languages spoken: Farsi

5.6.b
Packet Pg. 530 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 458
Question 30: Please indicate your gender identity.

Value Percent Total Responses
Female 63.6% 861
Male 30.4% 411
Non-binary 0.7% 9
Different Identity (please specify) 0.4% 5
Prefer not to say 5.0% 68
Total 1,354
Female
64%
Male
30%
Non-binary
1%
Different Identity
(please specify)
0%
Prefer not to say
5%

5.6.b
Packet Pg. 531 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 459
Spanish Survey Results
Value Percent Total Responses
Female 88.2% 15
Male 11.8% 2
Non-binary 0.0% 0
Different Identity (please specify) 0.0% 0
Prefer not to say 0.0% 0 Total 17

5.6.b
Packet Pg. 532 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 460
Question 31: What is your employment status?
Value Percent Total Responses
Full-time employed 43.4% 586
Part-time employed 9.5% 128
Unemployed 2.6% 35
Retired 40.6% 549
Homemaker 3.3% 44
Intern 0.3% 4
Full-time student 0.4% 5
Total 1,351
Full-time employed
43%
Part-time
employed
10%
Unemployed
3%
Retired
41%
Homemaker
3%
Intern
0%
Full-time
student
0%

5.6.b
Packet Pg. 533 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 461
Spanish Survey Results
Value Percent Total Responses
Full-time employed 64.7% 11
Part-time employed 17.6% 3
Unemployed 5.9% 1
Retired 5.9% 1
Homemaker 0.0% 0
Intern 0.0% 0
Full-time student 5.9% 1 Total 17

5.6.b
Packet Pg. 534 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 462
Question 32: What is your annual household income?
Value Percent Total Responses
$0 2.9% 35
$1-$9,999 0.8% 10
$10,000-$24,999 2.7% 33
$25,000-$49,999 7.0% 85
$50,000-$74,999 11.9% 145
$75,000-$99,999 13.6% 166
$100,000-$149,999 24.5% 299
$150,000-$174,999 10.6% 129
$175,000 and greater 26.0% 317
Total 1,219
$0
3%
$1-$9,999
1% $10,000-$24,999
3%
$25,000-
$49,999
7%
$50,000-$74,999
12%
$75,000-$99,999
13%
$100,000-$149,999
24%
$150,000-$174,999
11%
$175,000 and
greater
26%

5.6.b
Packet Pg. 535 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 463
Spanish Survey Results
Value Percent Total Responses
$0 0.0% 0
$1-$9,999 0.0% 0
$10,000-$24,999 6.3% 1
$25,000-$49,999 18.8% 3
$50,000-$74,999 12.5% 2
$75,000-$99,999 25.0% 4
$100,000-$149,999 31.3% 5
$150,000-$174,999 0.0% 0
$175,000 and greater 6.3% 1 Total 16

5.6.b
Packet Pg. 536 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 464
C.3. PUBLIC COMMENT PERIOD
Once the draft Plan was completed, the public was given an opportunity to review and provide comments on Volume 1 (Planning Area-wide Elements) and each of the jurisdiction annexes prior to submitting the Plan to the State and FEMA. The countywide public comment period began on April 22, 2024, and went on through May 31, 2024. Prior to the public comment period, the Core Planning Team conducted a strategy meeting with all plan participants that served as brainstorming session and helped determine the public outreach goals and proper outreach methods for the public comment period. Subsequently, the Core Planning Team developed a public outreach strategy tool meant to guide each participating jurisdictions in their own public outreach strategies. The Core Planning Team held a second strategy meeting with all plan participants midway through the public comment period to provide additional support and guidance, if needed.

Each plan participant developed their own public outreach strategy that meets the unique needs of their community to engage stakeholders and the public during the public comment period.

Public engagement participation and supporting documentation for each plan participant can be found in their respective annexes.

Contra Costa County OES coordinated with its county departments and participating jurisdictions to ensure that the public had an opportunity to learn about the Plan, mitigation actions planned for their communities, and ways to get involved in the planning process. Since many residents are covered by multiple annexes (e.g., municipalities and special districts), the County made outreach events available for all plan participants. This allowed the community to learn about the difference between Volume 1 (Planning Area-wide Elements), the annexes, and the multiple ways they might be covered by a Hazard Mitigation Plan. To ensure equitable outreach a calendar was created to strategize and map all events.

Contra Costa County has many vulnerable communities, including younger (under 18 years old) and elderly (over 65 years old) population, individuals with limited English proficiency, and those with access and functional needs. Throughout these outreach events, Contra Costa County OES presented not only Volume I, but additional plans included in the planning process. This was especially important in the unincorporated areas as many special districts, including reclamation districts, participated in the planning process.

Working with the Board of Supervisor staff, the County presented to unincorporated communities across the county through 10 different Municipal Advisory Council (MAC) meetings and a Tactical Advisory Council Meeting. This allowed the County to bring the Hazard Mitigation Plan to specific communities while also working with trusted community agents to support and spread the message. All MAC agendas in the County are posted online and in public spaces 72 hours in advance, thus allowing high visibility on the agenda and enough time for individuals to review the presentations. Additionally, all MAC meetings were held after hours, which allowed OES to present to different members of these communities. The County collaborated with Contra Costa County Fire Protection District, Rodeo-Hercules Fire Protection District, Department of Public Works, Flood Control and Water Conservation District, and Ironhouse Sanitary District to present at six (6) different meetings throughout the County.

Additional Outreach through Board of Supervisor Councils such as the Advisory Council on Equal Employment Opportunity, Advisory Council on Aging, and Head Start Policy Council, further allowed us to reach the County’s underserved populations. Furthermore, each council was asked to distribute hazard mitigation information to their respective demographics. The councils are comprised of county staff from various departments and community representatives countywide.

5.6.b
Packet Pg. 537 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 465
Additional outreach was through community events such as the John Muir Houses’ Earth Day Celebration, where the County was able to target members regionally. The historic John Muir House attracts many people throughout the region, not just Contra Costa County. The Bay Point Bike Rodeo and Safety Fair attracted many community members on the county's East side, an area with a high population of limited English language speakers and high poverty rates.

The County partnered with the Employment and Human Services Department (EHSD) to conduct onsite hazard mitigation education and outreach in schools and community events in Richmond, San Pablo, Hercules, Antioch, Oakley, and Pleasant Hill. EHSD Navigators also placed hazard mitigation plan outreach materials in all their active school sites. This was a new partnership for Contra Costa County OES, and the collaboration ensured the information was presented from trusted community partners.

Contra Costa County OES provided a training session to EHSD Navigator staff on the County’s Hazard Mitigation Plan, the planning process, hazards, and how to present the information. Additionally, OES provided EHSD with printed materials, both flyers and trifolds, in all five (5) threshold languages. Due to their collaboration and support, we were able to reach local youth at school, senior citizens, and people who may have a difficult time participating in other events. The EHSD Navigator events included:

Date Event Name Municipality
May 17, 2024 Clean Slate Day Richmond
May 17, 2024 Peres School Event Richmond
May 18, 2024 Immigration Forum San Pablo
May 22, 2024 Senior Information & Health Fair Richmond
May 24, 2024 Youth & Young Adult Career Fair Richmond
May 29, 2024 West Contra Costa Career Fair Hercules
May 30, 2024 Community Resources Fair Antioch
June 1, 2024 O’Hara Park Middle School Resource Fair Oakley June 1, 2024 Medical Coverage Registration Fair Oakley
June 3, 2024 West County Community Partnership Meeting Pleasant Hill Other community agencies were also vital in the County’s public outreach efforts. The American Red Cross presented information on the County’s Hazard Mitigation Plan at events that took place during the outreach period and during Leadership Council meetings. Materials were presented to leaders from nonprofits, cities, and counties, providing the opportunity for them to comment and continue sharing the message.

5.6.b
Packet Pg. 538 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 466
Public Comment Outreach Calendar
April 2024
Date Thursday, April 11th Wednesday, April 17th
Event Name EHSD Navigator Training East Richmond Heights MAC Location 3105 Willow Pass Road
Bay Point, CA 94565
Open Door United Methodist Church
6226 Arlington Boulevard
Richmond, CA 94805
Outreach Method Community Event Presentation to Governing Body Outreach Purpose Inform, Involve Inform, Involve
Targeted Population
Countywide (Access and Functional
Needs, Age, High Poverty, Limited Access
to Transportation)
Countywide (Access and Functional
Needs, Age, Limited English Proficiency)
Accommodations Provided Mobile After Hours, Spanish Speaker Available Date Saturday, April 20th Tuesday, April 23rd
Event Name John Muir Birthday/Earth Day Byron MAC
Location 4202 Alhambra Avenue
Martinez, CA 94553
St. Anne’s Church
2800 Camino Diablo (Room 1-A)
Byron, CA 94514
Outreach Method Community Event Presentation to Governing Body Outreach Purpose Inform, Involve Inform, Involve
Targeted Population Countywide (Access and Functional
Needs, Age)
Countywide (Age)
Accommodations Provided After Hours, Spanish Speaker Available After Hours, Spanish Speaker Available Date Wednesday, April 24th Wednesday, April 24th
Event Name Kensington MAC Contra Costa Sustainability Exchange Location
Kensington Library
61 Arlington Avenue
Kensington, CA 94707
Virtual
Outreach Method Presentation to Governing Body Roundtables/Forums Outreach Purpose Inform, Involve Inform, Involve
Targeted Population Countywide (Age, Access and Functional Needs)
Countywide Effort, County Staff
Accommodations Provided After Hours Online, Posted Meeting Video

5.6.b
Packet Pg. 539 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 467
April 2024
Date Wednesday, April 24th Thursday, April 25th
Event Name
Coffee with a Cop
(Local Mental Health Evaluation Team
coordination with law enforcement and the
public)
Rodeo MAC
Location Concord-Gratitude
Rodeo Senior Center
189 Parker Avenue
Rodeo, CA 94572
Outreach Method Community Event Presentation to Governing Body Outreach Purpose Inform, Involve Inform, Involve
Targeted Population Countywide (Age, Access and Functional Needs)
Countywide (Age, Access and Functional
Needs)
Accommodations Provided In Person Outreach After Hours
Date Thursday, April 25th Friday, April 26th
Event Name Contra Costa County Public Health
Volunteer Appreciation Event
Advisory Council on Equal Employment
Opportunity
Location 2732 Systron Drive, #250
Concord, CA 94518 Virtual
Outreach Method Community Event Presentation to Governing Body Outreach Purpose Inform, Involve Inform, Involve
Targeted Population Countywide (Age, Access and Functional Needs) Countywide (Age)
Accommodations Provided Spanish Speaker Available Digital Access, Spanish Speaker Available Date Saturday, April 27th
Event Name Bay Point Bike Rodeo
Location
Ambrose Rec Center
3105 Willow Pass Road
Bay Point, CA 94565
Outreach Method Community Event
Outreach Purpose Inform, Involve
Targeted Population Countywide (Age, Socially Vulnerable) Accommodations Provided Weekend Event

5.6.b
Packet Pg. 540 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 468
May 2024
Date Saturday, May 4th Tuesday, May 7th
Event Name El Sobrante Neighborhood Meeting North Richmond MAC Location El Sobrante
North Richmond Senior Center
515 Silver Avenue
North Richmond, CA 94801
Outreach Method Community Event Presentation to Governing Bodies Outreach Purpose Inform, Involve, Engage Inform, Involve Targeted Population Countywide (Elderly) Countywide (High Poverty, Age, Limited English Proficiency)
Accommodations Provided Weekend Event After Hours, Spanish Speaker Available Date Tuesday, May 7th Wednesday, May 8th
Event Name Alamo MAC El Sobrante MAC
Location
Alamo Women’s Club
1401 Danville Boulevard
Alamo, CA 94507
El Sobrante Library
4191 Appian Way
El Sobrante, CA 94803
Outreach Method Presentation to Governing Bodies Presentation to Governing Bodies Outreach Purpose Inform, Involve Inform, Involve
Targeted Population Countywide (Age, Access and Functional Needs)
Countywide (High Poverty, Age, Limited
English Proficiency)
Accommodations Provided After Hours After Hours, Recording, Virtual Option, Spanish Speaker Available
Date Wednesday, May 8th Tuesday, May 14th
Event Name Pacheco MAC Diablo MAC
Location
Pacheco Community Center
5800 Pacheco Boulevard
Pacheco, CA 94553
Diablo County Club
1700 Club House Road
Diablo, CA 94526
Outreach Method Presentation to Governing Bodies Presentation to Governing Bodies Outreach Purpose Inform, Involve Inform, Involve
Targeted Population Countywide (Age, Access and Functional Needs)
Countywide (Age, Access and Functional
Needs)
Accommodations Provided After Hours, Recording, Virtual Option, Spanish Speaker Available After Hours, Spanish Speaker Available Date Tuesday, May 14th Tuesday, May 14th
Event Name Bethel Island MAC WCC Fire Safe Council Advisory Board Location
Scout Hall
3090 Ranch Lane
Bethel Island, CA 94511
Virtual
Outreach Method Presentation to Governing Bodies Presentation to Governing Bodies Outreach Purpose Inform, Involve Inform, Involve
Targeted Population Countywide (Age, Access and Functional Needs, High Poverty)
Countywide (Age, Access and Functional
Needs, High Poverty)
Accommodations Provided After Hours Virtual Option, Spanish Speaker Available

5.6.b
Packet Pg. 541 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 469
May 2024
Date Wednesday, May 15th Wednesday, May 15th
Event Name Advisory Council on Aging Head Start Policy Council Location Virtual 500 Ellingwood Way
Pleasant Hill, CA 94523
Outreach Method Presentation to Governing Bodies Presentation to Governing Bodies Outreach Purpose Inform, Involve Inform, Involve
Targeted Population Countywide (Age, Access and Functional Needs)
Countywide (Age, Access and Functional
Needs, High Poverty)
Accommodations Provided Virtual Option, Spanish Speaker Available After Hours, Spanish Speaker Available Date Tuesday, May 21st
Event Name Knightsen MAC
Location
Knightsen Farm Bureau
3020 Second Street
Knightsen, CA 94548
Outreach Method Presentation to Governing Body
Outreach Purpose Inform
Targeted Population Countywide (Age, Access and Functional Needs, High Poverty) Accommodations Provided After Hours, Spanish Speaker Available The public comment period printed materials, website posts, social media samples, and agendas are below.

5.6.b
Packet Pg. 542 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 470
April 17, 2024 – East Richmond Heights MAC

5.6.b
Packet Pg. 543 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 471
April 24, 2024 – Byron MAC (Partnership with the City of Brentwood and Contra Costa County Fire Protection District)

5.6.b
Packet Pg. 544 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 472
April 24, 2024 – Kensington MAC and Coffee with a Cop (Concord)

5.6.b
Packet Pg. 545 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 473
April 24, 2024 – Rodeo MAC and Contra Costa Public Health Volunteer Appreciation Event

5.6.b
Packet Pg. 546 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 474
April 25, 2024 – Advisory Council on Equal Employment Opportunity

5.6.b
Packet Pg. 547 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 475
April 27, 2024 – Bay Point Bike Rodeo

5.6.b
Packet Pg. 548 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 476
May 6, 2024 – El Sobrante Neighborhood Meeting

5.6.b
Packet Pg. 549 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 477
May 7, 2024 – North Richmond and Alamo MACs (Partnership with Contra Costa County Public Works Department and Contra Costa County Flood Control and Water Conservation District)

5.6.b
Packet Pg. 550 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 478

5.6.b
Packet Pg. 551 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 479
May 8, 2024 – Pacheco MAC (Partnership with Contra Costa County Public Works Department, Contra Costa County Flood Control and Water Conservation District, and El Sobrante MAC)

5.6.b
Packet Pg. 552 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 480
May 14, 2024 – West Contra Costa Fire Safe Council Advisory Board Presentation (Partnership Contra Costa County Fire Protection District)

5.6.b
Packet Pg. 553 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 481
May 14, 2024 – Diablo MAC and Bethel Island MAC (Partnership with Contra Costa County Public Works Department, Ironhouse Sanitary District, Contra Costa County Fire Protection District)

5.6.b
Packet Pg. 554 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 482

5.6.b
Packet Pg. 555 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 483
May 15, 2024 – Advisory Council on Aging and Head Start Policy Council

5.6.b
Packet Pg. 556 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 484
May 21, 2024 – Knightsen Tactical Advisory Council (Partnership with Contra Costa County Public Works Department and Contra Costa County Fire Protection District)

5.6.b
Packet Pg. 557 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 485
May 29, 2024 – Contra Costa County Fire Protection District Town Hall in Brentwood (Partnership with the City of Brentwood and Contra Costa County Fire Protection District)

5.6.b
Packet Pg. 558 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 486
Figure C-4 Presentation Template

5.6.b
Packet Pg. 559 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 487

5.6.b
Packet Pg. 560 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 488

5.6.b
Packet Pg. 561 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 489

5.6.b
Packet Pg. 562 Attachment: B: 2024 Contra Costa Hazard Mitigation Plan Volume 1 (2025-018 : Adopting Volume 1 and the City of San Ramon’s Portion) 2024 Hazard Mitigation Plan
Contra Costa County, California
Appendix C: Public Engagement 490
Printed Materials
Printed materials were distributed in the County's five (5) top languages – English, Spanish, Tagalog, and Traditional and Simplified Chinese. Materials were distributed at all public meetings and outreach events. Additionally, plan participants were given access to edit the designs for their own use. Having the materials available in multiple languages allowed more of the community to receive information about the Hazard Mitigation Plan, ways to comment, and how to prepare for disasters. Printed materials are especially helpful to communities with Limited English Proficiency as the materials include a visual component.

San Ramon City CouncilFebruary 25, 2025

San Ramon City Council
February 25, 2025